Get 20M+ Full-Text Papers For Less Than $1.50/day. Start a 14-Day Trial for You or Your Team.

Learn More →

QFD Model Based on a Suitability Assessment for the Reduction of Design Changes in Unsatisfactory Quality

QFD Model Based on a Suitability Assessment for the Reduction of Design Changes in Unsatisfactory... When a design project is executed, inappropriate decisions in the selection of materials, construction methods, and systems negatively impact the productivity of the project since such decisions result in inadequate design. Subsequently, these defects become a cause for design changes. In order to prevent such cases, clear RPC (Requirement Performance Criteria) should be provided in order to allow for suitable design alternatives, and a quality review should be undertaken by tracking alterations in the requirements, as these continuously change and update. This study suggests a quality function deployment (QFD) model that is based on a suitability assessment (QFD-SA) to prevent design changes that result in unsatisfactory quality. The suggested assessment model is able to define the function and performance requirements, and it is thus suitable for use when selecting design alternatives for those requirements. The model uses a matrix technique in its assessment, and furthermore, the QFD-SA assessment model reanalyzes the degree of conformity according to the changes in the RPC. Keywords: QFD (Quality Function Deployment); design change; requirement; performance; suitability 1. Introduction requirement definitions and insufficient sharing of Design changes inevitably occur during the building information between project stakeholders were major design process. There can be a number of causes causes of design changes (Isacc and Navon 2008). for these design changes, including amendments in Design errors, missing functions, and alternative regulations, additional client needs, changes in the selection errors are among the various causes of design original requirements, design errors caused by the changes that can possibly be improved by quality designer, missing functions, and alternative selection management activities performed by administrators. errors. An investigation performed by the Procurement The above mentioned factors altogether represent Agency, which is the representative institution that the types of design changes that can occur and places design orders for domestic facilities, pointed out subsequently result in unsatisfactory quality, which that inadequate design and subsequent design changes means that there are inconsistencies in the work with are a major factor that negatively impacts facilities respect to the requirements of the design. In contrast, (Procurement Agency 2004). the additional needs of the clients and changes in the According to an investigation on the frequency of original requirements result in somewhat different flaws during the design review of apartment houses characteristics for the design work. These are situations and office buildings (Kwak and Kim 2010), alternative that occur due to uncertainty of design work and to selection errors and missing functions were the most the nature of collaborative work involving numerous frequent source of design defect. A lack of a usability stakeholders. review performed by the client, missing representations In conclusion, all of these factors are caused on the drawings, and discrepancies in the information by inadequate criteria for the requirements or by between the different construction works followed, discrepancy between the requirements and the design in that order. Another study indicated that insufficient solutions. Hence, the causes for design changes resulting from unsatisfactory quality may be classified into two categories: first, discrepancies between the *Contact Author: Jaeho Cho, Research Professor, required quality and that of the design solution; and Department of Architectural Engineering, Dankook University, second, vague descriptions of the RPC. Fig.1. below 152, Jukjeon-ro, Suji-gu, Yongin-si, Gyeonggi-do, shows a schematic of the types of design changes 448-701, Korea resulting from unsatisfactory quality, among the entire E-mail: cjhace@naver.com causes for design changes. As a result, clear criteria ( Received April 7, 2014 ; accepted October 30, 2014 ) Journal of Asian Architecture and Building Engineering/January 2015/120 113 should be presented with respect to the required quality suitability according to the RPC. (5) Validate the utility and the proper decision-making technique for an of the QFD-SA model by analyzing specific cases. (6) assessment of quality conformity should be performed Address the conclusions of this study. in order to reduce the number of design changes due to unsatisfactory quality. 3. Literature Review The existing research was surveyed and the themes of the relevant studies were divided into two categories: the 'study of design changes' and the 'study of decision making techniques'. (1) Study of Design Changes in Building Studies discussing design changes have been actively conducted both within Korea and abroad. With respect to domestic research, the majority of these have focused on performing environmental analyses of design changes, related policy issues, cooperative design methods, and quality management processes that prevent design changes. Ahmed et al. (2003) implemented a QFD model as an assessment tool to find alternatives to design changes and to keep track of the requirements requested by the owner. In addition, they suggested a new method to manage information on the Fig.1. Cause of Design Change Due to Unsatisfactory Quality requirements of the project as well as to communicate The fundamental concepts of quality management the process for the design changes. Oh (2007) analyzed are to define the requirements of the project and to the factors that could result in design changes in implement the design based on the requirements. construction projects, and suggested ways to improve An accurate and clear definition of quality is that the construction changes in the environment. Isaac and "Quality is conformity to the requirements." In 1979, Navon (2008) examined the causes for interruptions Phillip Crosby described the concept of quality in his that occur in functions specified in design changes, and work, 'Quality Is Free: The Art of Making Quality also proposed a tool for automated design changes that Certain'. allow users to trace relationships that exist between A comprehensive understanding of the 'required the given requirements and the design production. function', 'required performance criteria', and 'product This ensures that the stakeholders involved in the performance' is essential to effectively manage decision process, in which change proposals are quality. Hence, this study suggests a Quality Function evaluated, will know the scope of the implications Deployment based on a Suitability Assessment (QFD- of the change in advance. Kim et al. (2009) analyzed SA) model that defines the required function and the the main cause for design changes that have occurred RPC by using the QFD. Thus, this model allows for an during building construction and proposed a process assessment of the suitability of the design alternatives model that supports those design changes. Lee and by following the alterations in the requirements. The Chun (2012) also investigated design changes and suggested model can support users to make appropriate proposed a quantitative assessment method that could decisions, and prevent design changes by essentially handle alternative designs by taking into account cost, improving the causes of the design changes. performance, and constructability. Despite systematic approaches to the causes and problems of design 2. Methods and Ranges of Study changes that we have seen when discussing existing This study proposes a decision-making technique research, it was revealed that the proposal of a quality that is based on RPC for the assessment of quality assessment model were very rare in order to improve conformity and suitability, and undertaken by inadequate design and the proposals of processes in performing the following steps. order to improve unsatisfactory quality. (1) Evaluate the status of the existing research. (2) Study of Decision Making Techniques The themes of the research were categorized into Decision-making during the design process should two categories, including 'study of the reduction be undertaken with caution since the subsequent of the design changes' and 'study of the decision- phase directly affects the next phase. In particular, making technique'. (2) Determine the causes for the inappropriate decision-making during the planning design changes of an unsatisfactory quality type via phase and the schematic design phase results in various case investigation. (3) Propose a process for quality forms of productivity loss since those decisions management following alterations in the requirements. themselves become a direct cause of design changes at (4) Propose a quality assessment model based on the construction document phase or construction phase. 114 JAABE vol.14 no.1 January 2015 Jaeyoul Chun The Analytic Hierarchy Process (AHP), Forced- been suggested, a research theme has not yet found Decision Method (FDM)/Improved Weight Decision a conformity assessment and suitability assessment Method (IWDM), Weighted Comparison Matrix according to the RPC. method (WCM), VE-Matrix Evaluation Method, and QFD are decision-making techniques that are broadly 4. Analysis of the Causes of Design Changes due to utilized in both industry and academia. Unsatisfactory Quality Lee and Chun (2009) utilized the FDD/IWDM Design changes are caused when a design is not method to evaluate the alternatives. The features of the suitable for any of the project requirements in terms FDD/IWDM method are that the relative priorities of of the schedule, cost, or quality. In addition, design the function can be evaluated. change factors exist over the entire scope of the The VE-Matrix Method uses a rating scale for construction project, such as alterations in the client's linguistic assessment (Caltrans Value Analysis Report requirements, amendments to the regulation systems, Guide, 1999). In this scale, the function ideas are and a diversification of the construction methods. evaluated by using a 10-point rating scale. The VE It is impossible to conduct perfect schematic Matrix Method allows users to evaluate performance design and design development that does not involve and to set the priorities of the functions. Users can design changes. Table 1. below shows the results of then set the evaluation items, such as the degree of investigation on cases of design changes based on 26 satisfaction of the function, constructability, and cases of private office buildings. economic feasibility. The VE Matrix Evaluation The factors that cause design changes can be method is then used to choose the optimal alternatives categorized by items and by operating organization. by estimating the priorities of each of the evaluation The operating organizations that cause design changes items, and as a result, this method is suitable for a have been revealed as designers in the first place, comparison of the quality of the design alternatives. clients in the second place, and contractors in the In addition to the three methods mentioned above, third place. The items that cause design changes are QFD is has also been considered as a representative shown as 'changes in schematic design' first, 'material method for decision-making. The QFD method is a changes and quantity growth' and 'ambiguous design quality assessment method that can be widely used in and missing function' second, and 'inconsistency in industry, and it was created by Mitsubishi in 1972. design solution based on field conditions' and 'client's This method analyzes the function and the additional requirements' third. performance that comprise quality by converting This study does not present the representative causes the client's requirements into a design quality for all design changes, but only provides a rough list definition. The components of the QFD are the of the causes. The results shown in Table 1. allow us client's requirements, extraction of quality factors in to deduce the design changes that were caused with the requirements, estimation of the priorities in the respect to quality. required quality, and a weighting priority conversion. The change types, including schematic designs, Kwak (2011), Yoo and Yi (2005), and Yang and Kim fluctuations in quantity, civil complaints, and (2005) used QFD to perform a quality assessment. unpreventable natural disasters are natural phenomena Prasad (2013) evaluated product quality in terms of that are caused by uncertainty, which is part of the performance for each design alternative by using QFD. nature of architectural design. Improvements in the Quality evaluation system proposed by Prasad (2013) design quality, including changes from such causes, is a representative case utilizing QFD. Li et al. (2014) require different approaches. However, the types proposed a new method of multi criteria decision- including 'ambiguous design', 'missing function', making by combining QFD and TOPSIS evaluation and 'selection error of the construction methods' models. Many other studies on the QFD method are considered as the type of design changes that have been presented, and case studies of specific are a result of unsatisfactory design. These, in turn, applications are continuously in progress. are caused when the quality of the design does not QFD has strengths and weaknesses as follows. meet the necessary quality threshold, or when the The QFD method creates a novel idea, mainly by requirements are not clearly defined. The 'inconsistency considering the performance priorities for quality and with field conditions' item is another cause for design by focusing on quality improvements. While the RPC changes that are due to unsatisfactory quality, and it may be defined by the QFD, the degree of suitability is highly related to the 'interference among building of quality based on the RPC may not be evaluated. As system functions', 'function errors' and 'performance we have discussed, research related to the decision- discrepancies'. making techniques discussed above have revealed that The following issues should be reviewed in order to decision-making techniques are able to assess the value reduce the occurrence of such items. scores by focusing on function. ① Check if the design alternatives show conformity Although several methods for a quantitative to the required performance criteria of the field project. evaluation of the function and the performance have JAABE vol.14 no.1 January 2015 Jaeyoul Chun 115 ② Check if the performance of the design alternatives interferes with that of adjacent systems. ③ Check if there are self-contradictions between the functions of alternative design. Fig.2. shows the concept diagram of the quality suitability and the causes for design changes of an unsatisfactory quality type. Fig.3. Concept of Quality Assessment upon the Changes Therefore, a quality assessment process that prevents design changes can be performed with the following 4 steps: (1) Setting the function priority and the agreed definition of the required functions by the project stakeholders. (2) Setting the relationships associated with the required functions and the RPC. (3) Verification of the contradictory function and the interference of the RPC. (4) Review of the conformity and suitability of the quality between the design Fig.2. Design Change in Quality Dissatisfaction alternatives and the requirements. 5. Quality Management Process Based Upon Changes in Requirements 6. QFD Model based on Suitability Assessment Clear definitions of the required functions are The 'QFD-SA' method adopts the CVAG (Caltrans essential for the selection of design alternatives since Value Analysis Guide, 1999) linguistic assessment. each project has unique characteristic and properties. A 5-point Likert scale is used to assess the function In addition, changes in the required function and in the priority. RPC frequently occur as a result of the innate nature of The QFD-SA method and the QFD method share the design process. a common feature for defining the relevance of the The RPC is redefined during a mutual review performance items related to function. The QFD-SA process by experts from each design discipline, method differs from the QFD method in respect of and these are continually revised during the design suitability against the RPC. process. Therefore, the assessment of conformity The RPC m ay be defi ned as the minim um and the suitability of the design alternatives should performance values or as the recommended be performed in an environment with continuously performance values. These criteria are related to changing requirements. A concept diagram of the functions that are utilized in the assessment of the design quality management for the changes in the conformity and the suitability through a comparison requirements of each phase of the design process is with the given RPC. A concept diagram of the shown below in Fig.3. suitability assessment is presented in Fig.4. Since changes in the requirements also alter the The suitability scale is '0' when the required RPC, technical decision-making is required to solve performance criteria are the same as the performance conflicts with existing systems and interference of the alternatives; and a zero value is used for strict between the requirements. conformity. For example: if the performance value of Table 1. Analysis of the Factors Concerning Design Changes (The 26 Cases of Office Buildings) Item Causes of the Design Changes Owner Designer Contractor Frequency Ranking Relation 1 Additional Client's Needs 10 - - 10 3 Quality 2 Selection Error of Construction Methods - - 9 9 4 Quality 3 Material Changes, Quantity Growth 5 - 7 12 2 Quality 4 Inconsistencies in the Design and the Field - 10 - 10 3 Quality 5 Inadequate Schematic Design - 8 - 8 5 Quality 6 Change in the Schematic Design (Volume of 12 14 - 26 1 Quality Space) 7 Unclear Design, Missing Features, Design Errors - 12 - 12 2 Quality 8 Omission of Construction Statement (bill) Item - - 8 8 5 Cost 9 Civil Complaints 4 - 2 6 7 - 10 Safety Assurance - 7 - 7 6 Quality 11 Unpreventable Natural Disasters 2 1 2 5 8 - 116 JAABE vol.14 no.1 January 2015 Jaeyoul Chun rd nd the alternative is higher than the RPC by a score of 2 score of 4, the 3 rating a score of 3, the 2 rating a score st in the performance ratings, then the suitability score is of 2, and the 1 rating a score of 1. In the case where the 2. If the performance value of the alternative is higher performance evaluation for the alternatives is either a than the RPC by a score of 1, then the suitability nominal rating or a binary rating, such a scale readjusts to score is 1, if the performance value of the alternative the corresponding rating to provide a normalization score. is equivalent to the minimum performance, then the ④ Correlation Analysis of Function and Performance suitability score is 0, if the performance value of the (CAFP): The correlation between the function and the alternative is lower than the RPC by a score of 1, then performance is evaluated. For example, an extremely the suitability score is -1, and if the performance value high correlation (●) has 1 point, a high correlation (○) of the alternative is lower than the RPC by a score of 2, has 0.8 points, a moderate correlation (▲) 0.6 points, then the suitability score is -2, etc. and a low correlation ( ▽ ) 0.4 points. The scale of the correlation is not absolute, and the user can choose among various scales. ⑤ Satisfaction Analysis for Required Performance Criteria (SARPC): Review the quality satisfaction through a comparison of the RPC that are specified in the design guidelines and the performance grade of the product alternative. Dissatisfaction mark (▲) is presented. And satisfaction mark (● ) is presented. ⑥ Interference Analysis for Required performance Criteria (IARPC): One value of the RPC is set as the standard, and an interference mark ( △ ) is presented, when the RPC differ from one another. If no interference occurs, it is presented with (-). ⑦ Function Satisfaction Analysis (FSA): Review the function satisfaction through a comparison with the required performance criteria. FSA is determined, Fig.4. Conceptual Diagram of Conformity and and Suitability when the suitability score is the same as, or higher than In the case of the other scales, such as the nominal 0 point. The function satisfaction is presented with scale or the binary scale, the suitability scale is also ( △ ). Function dissatisfaction is presented with (○ ). readjusted according to the normalization of the zero ⑧ TFSS (Total Function Suitability Score): Assign rating point. Fig.5. presents the basic format of the the suitability scores by comparing the performance 'QFD-SA' method. values of the product. TFSS (Total Function Suitability Score: V) for the design alternatives are estimated by summing up the FSS. Fig.5. QFD Concept Model-based on a Suitability Assessment ① Function Definition (FD): The process for defining a function is proposed in the literature and is ⑨ SIUL (Suitability Index based on Unsatisfactory ... (1) related to VE and the 'FAST Diagram' method. The Level): This value is the sum of the FSS that are less defining function in this study shows only the detailed than 0 divided by the absolute maximum total of definition of the function. SUSS. ② Function Weight (FW): The function weight is ……………………..……... (2) ... (1) determined by using a 10-point scale. For example: maximum priority = 10 points, moderate priority = 5 points, minimum priority = 1 point. …………..….…………..……... (3) ③ Performance of Design Solution (PDS): The ……………………..……... (2) performance is evaluated and classified into 5 ratings. th th For example: the 5 rating is a score of 5, the 4 rating a ..….…. (4) …………..….…………..……... (3) JAABE vol.14 no.1 January 2015 Jaeyoul Chun 117 ..….…. (4) ……………………..……... (5) ……………………..……... (6) ……………………..……... (5) ….…… (7) ……………………..……... (6) .……. (8) ….…… (7) .……. (8) .……. (9) ... (10) .……. (9) ... (10) ... (1) ……………………..……... (2) ... (1) ⑫ FCD (Function Conformity Deviation): The FCD …………..….…………..……... (3) is obtained by calculating the distance between the ……………………..……... (2) SIUL and the SISL. The Sub-Function Conformity Deviation (SFCD) is the distance between the USIF SISL (Suitability Index based on Satisfactory and SSIF. ..….…. ... (1) (4) level): This value is the…………..… sum of the .… suitability ………..…… scores ... (3) that are greater than 0 divided by the maximum total of 7. Case Study SSSS. In order to verify the validity of the 'QFD-SA' method, the suitability was evaluated for the required ……………………..……... (2) ……………………..……... (5) ..….…. (4) function that was initially planned, and then it was compared against the suitability of the required function that was altered. ……………………..……... (6) …………..….…………..……... (3) (1) Summary of the Case Study ……………………..……... (5) The QFD-SA technique can be applied to window desi gn. Windows are expected to have several ….…… (7) characteristics, such as insulation performance (Heat ..….…. (4) ……………………..……... (6) Transmittance: U Value), Solar Heat Gain Coefficient (SHGC), Visible Light Transmittance (VT), Air .……. (8) Leakage (AL), Condensation Resistance (CR), TFCI (Total Function Conformity Index): This and Outdoor Indoor Transmission Class (OICT). ……………………..……... (5) ….…… (7) value is the estimated CSS divided by the maximum Thermal comfort in spaces (a required function) can SSSS or the maximum SUSS. For the negative sums of be determined by the complex performance of these .……. (8) CSS, the estimated CSS are divided by the maximum features. Window performance and the standard rating ……………………..……... (6) SUSS. For the positive sum of CSS, the estimated CSS grades that have been analyzed are summarized below .……. (9) are divided by the maximum SSSS. in Tables 2. and 3. Table 2. Performance Value of the Alternative Design Solutions ….…… (7) ... (10) Solutions U-Value SHGC VT AL CR OITC 0.49 0.33 0.55, 0.20 71 32 Alt-(1) .……. (9) .……. (8) (Gr.3) (Gr.4) (Gr.3) (Gr.4) (Gr.4) (Gr.4) 0.38 0.48 0.35, 0.25 30 27 Alt-(2) (Gr.4) (Gr.3) (Gr.2) (Gr.3) (Gr.2) (Gr.2) ... (10) 0.47 0.52 0.50, 0.24 58 27 Alt-(3) (Gr.3) (Gr.2) (Gr.3) (Gr.3) (Gr.3) (Gr.2) 0.31 0.46, 0.55, 0.36 49 35 Alt-(4) (Gr.4) (Gr.3) (Gr.3) (Gr.2) (Gr.3) (Gr.4) .……. (9) Table 3. Performance Utilizing a 5-Point Rating Scale Grade-5 Grade-4 Grade-3 Grade-2 Grade-1 Performance (score 5) (score 4) (score 3) (score 2) (score 1) ... (10) U-factor 0.00 ~ 0.20 0.20 ~ 0.40 0.40 ~ 0.60 0.60 ~ 0.80 0.80 ~ 1.00 SHGC 0.20 ~ 0.30 0.30 ~ 0.40 0.40 ~ 0.50 0.50 ~ 0.60 0.60 ~ 0.70 VT 1.00 ~ 0.80 0.80 ~ 0.60 0.60 ~ 0.40 0.40 ~ 0.20 0.20 ~ 0.00 AL 0.00 ~ 0.10 0.10 ~ 0.20 0.20 ~ 0.30 0.30 ~ 0.40 0.40 ~ 0.5 CR 100 ~ 80 80 ~ 60 60 ~ 40 40 ~ 20 20 ~ 0 OICT 40 ~ 36 36 ~ 32 32 ~ 28 28 ~ 24 24 ~ 20 Fig.6. The Case Analysis of the QFD-SA for Alternative (1) 118 JAABE vol.14 no.1 January 2015 Jaeyoul Chun The RPC is defined to comply with the design (1) is based on the alterations in the requirements that guidelines for the characteristics of insulating windows were revealed in the SIUL function as -0.13. The SISL in the North-central United States, which has a similar was obtained as +0.04. The TFSS was -11.29. The climate to Korea (i.e. mixed hot and cold climates). TFCI for Alternative (1) was evaluated as -0.16, and (2) QFD-SA Case Study based on the Definition of the FCD of the alternative was calculated as 0.17. the Original Function (4) Discussion of the Analysis Fig.6. shows a case of the function assessment for Once the RPC are determined, the FCI is obtained Alternative (1) based on the QFD-SA method. The SIUL according to the performance value of the design was evaluated as -0.09 in the analysis of Alternative (1). alternatives. A closer FCI, TFCI consists of 0 points, The SISL was revealed to be +0.09, and the TFSS which is the greatest conformity that can be achieved was obtained as 0.49. The TFCI for Alternative (1) was with respect to the required function. Also, the higher the calculated as 0.01, and the FCD for Alternative (1) was FCI and TFCI, the greater the satisfaction with respect calculated as 0.18 (0.09-(-0.09)). to the required function that is thought to be obtained. (3) A Case of the QFD-SA Analysis based on the Although the design alternative shows a high value for Definition of the Changed Function TFCI, the alternative is considered to be unsuitable in The requirements are changed based on the RPC. the design if an SIUL arises to some extent. Alterations in requirements occur due to the client's Therefore, both the TFCI and the SIUL should be additional request concerning improvement in thermal considered for proper selection of an alternative. Fig.7. insulation performance and reduction in cooling load presents the results of a QFD-SA analysis based on during summer time. The following 4 changes were the definition of the original requirements for 4 design made in the function. alternatives, and the changes in the requirements for ① Change in the FW: function 1 (from 4.3 to 6.2), the 4 design alternatives, respectively. function 5 (from 4.8 to 7.8), and function 8 (from 4.3 For QFD-SA based on the original definition, to 8.0). ② U-Value performance ratings for function 'Alternative 1' recommends the proper design that shows rd 1 and function 5: Changed from the 3 rating to the the minimum SIUL of -0.09 with the TFCI of 0.008 (about th 4 rating. ③ SHGC performance rating for function 0.01). On the other hand, 'Alternative 4' shows the SIUL th th 1: Changed from 4 rating to 5 rating. (Grade 5 of of -0.16 with the TFCI of 0.014 (about 0.01). SHGC performance reduces energy cost by blocking For the QFD-SA based on the change definition, more solar heat compared to Grade 4.) ④ AL rating for 'Alternative 1' is recommended as the proper design function 1, function 5, and function 8: Changed from alternative, which shows the SIUL of -0.13 with the rd th 3 rating to 4 rating. TFCI of -0.16. 'Alternative 1' has the minimum SIUL The QFD-SA analysis is performed again according of -0.13 and the highest TFCI of -0.16. to the changes in the RPC. The analysis for Alternative In conclusion, the decision makers are not able to Fig.7. TFCI and SIUL/SISL of Alternative Designs by the QFD-SA JAABE vol.14 no.1 January 2015 Jaeyoul Chun 119 4) Cho, K.M. (2014) Evaluation of Technologies Ensuring Green clearly recognize an SIUL if the QFD-SA analysis is Performance in Multi-family Housing Projects in Korea. Journal of not performed by defining the RPC. The absence of Asian Architecture and Building Engineering. 13 (1), pp.133-139. an objective evaluation standard may result in a defect 5) Crosby P. (1979) Quality Is Free: The Art of Making Quality in the decision making with the selection of design Certain. McGraw-Hill Companies 1st edition. 6) Isaac, S. and Navon, R. (2008) Feasibility Study of an Automated alternatives. Unsatisfactory function with respect to the Tool for Identifying the Implications of Changes in Construction RPC is a major cause of design changes. Projects. Journal of Construction Engineering and Management, 134 (2), pp.139-145. 8. Conclusion 7) Jeong, J.S., Ryoo, I.W., and Lee, Y.W. (2006) A Study on the Choice of the Curtain-Wall Type and the Exterior Material These Design changes of an unsatisfactory quality are according to Commercial Building Images by using the AH, Korea caused by ambiguous requirements and by insufficient Institute of Construction Engineering and Management (Planning), quality assessments. A clear definition of the required 22 (11), pp.89-96. 8) Jung, J.H. and Lee, H.K. (2011) A Study on the Analysis of Contract function should be obtained, first of all, in order to Changing Situation for Public Construction Project. Regional secure the quality required, and thus prevent additional Association of Architectural Institute of Korea, 13 (04), pp.315-322. design changes. A clear recognition of the requirements 9) Kang, H.J. and Rhee, E.K. (2014) Development of a Sustainable and the implementation of the assessment based on Design Guideline for a School Building in the Early Design Stage, Journal of Asian Architecture and Building Engineering. 13 (2), the RPC allow for a significant reduction in the design pp.467-474. changes that occur due to unsatisfactory quality. 10) Kim, S.W., Nam, H.W., Lee, J.S., Shin, C.H., and Chun, J.Y. The QFD-SA quality assessment model that is (2009) Case Survey and Analysis for the Proper Design Changes proposed in this study supports assessments for the Management. Architectural Institute of Korea, Academic Annual Conference Proceedings. conformity and suitability of design alternatives, 11) Kwak, C. (2011) Study of the Method of Analysis for Main Causes according to the RPC. The QFD-SA method provides of Design Quality Declining using QFD in Construction Projects. a quantitative evaluation of the quality satisfaction Master's thesis, Sungkyunkwan University. for function and performance that design alternatives 12) Kwak, C. and Kim, Y.S. (2010) Building the Model of Analysis for the Main Causes of Design Quality declining in the Construction have. The following are the improvements of the QFD- Projects. Korea Institute of Construction Engineering and SA method in terms of the definition, analysis, and the Management, Academic Annual Conference Proceedings. evaluation of quality. 13) Lee, J.S. and Chun, J.Y. (2009) Risk Response Analysis Model (1) It allows for a reflection of both the definition of the for Construction Method Using the Forced-Decision Method and Binary Weighting Analysis. Journal of Asian Architecture and required function and alterations that the client intends. (2) Building Engineering, 8 (1), pp.205-212. It allows for an evaluation of the priority of the function, 14) Lee, J.S. and Chun, J.Y. (2010) Decision Making Process for and that of the related performances. (3) It allows for Alternative Selection of Proper Design Change in Construction Project. Korea Institute of Construction Engineering and an investigation of the self-interference between the Management, 11 (2), pp.74-81. performances of the required function in advance. (4) It 15) Lee, J.S. and Chun, J.Y. (2012) A Numerical Value Evaluation allows for an analysis of the conformity and suitability Model for the Optimum Design Selection. Journal of Asian of the design alternatives based on the RPC. (5) It Architecture and Building Engineering, 11 (2), pp.283-290. 16) L e e , K. I. , Ye om D.W. , a n d Ki m , E . J. ( 201 3) E xp e ri m e n t a l allows for the management of the suitability range of the Research on the Correlation of Temperature, Humidity, and CO quality by calculating a SIUL and SISL. (6) It allows for Level of a Rice Hull Insulated Indoor Environment, Journal of maintaining the user's goals by re-assessing the quality. Asian Architecture and Building Engineering. 13 (2), pp.221-217. A future study aims to investigate the broader 17) Li, M., Jin, L., and Wang, J. (2014) A new MCDM method combining QFD with TOPSIS for knowledge management utilization of QFD-SA by adopting it on a compound system selection from the user's perspective intuitionistic fuzzy scale that consists of a nominal scale, a binary scale, environment. Applied Soft Computing, 21, pp.28-37. etc. In addition, an assessment system for design 18) Oh, B.S. (2007) Study on the Analysis about Causes of Change quality that can be utilized in a web environment will based on Case Analysis of Construction Project on the Site. Seoul National University of Science and Technology, Master's thesis. also be developed. 19) Oh, Y.K. (2014) An Assessment Model for the Indoor Noise Environment of Aged Apartment Houses, Journal of Asian Acknowledgements Architecture and Building Engineering. 13 (2), pp.293-300. This research was supported by the National 20) Prasad, K. and Chakraborty, S. (2013) A Quality Function Deployment-based Model for Materials Selection. Materials and Research Foundation of Korea (NRF) (No. NRF- Design, 49, pp.525-535. 2012R1A1A2043186). 21) Procurement Agency (2004), Design Management Business Handbook. 22) Song, Y.W., Park, J.C., Chung, M.H., Choi, B.D., and Park, J.H. References (2013) Thermal Performance Evaluation of Curtain Wall Frame 1) Ahmed, S. M., Sang, L. P., and Torbica, Z. M. (2003) Use of Types, Journal of Asian Architecture and Building Engineering. 12 Quality Function Deployment in Civil Engineering Capital Project (1), pp.157-163. Planning. Journal of Construction Engineering and Management, 23) Yang, J.K. and Kim, S.Y. (2005) Improvement and Systematization 129 (4), pp.358-368. of Pre-Study Work for Design Value Engineering in Construction 2) Caltrans VA Report Guide 1999. State of California Department of Projects by Quality Function Deployment. Korea Institute of Transportation. Construction Engineering and Management, 6 (4), pp.122-129. 3) Cho, G.Y., Yeo, M.S., Kim, K.W. (2013) Design Parameters of 24) Yoo, S.Y. and Yi, J.S. (2005) A Basic Study on the Application Double-Skin Façade for Improving the Performance of Natural of QFD at Architectural Design Phase. Korea Institute of Ventilation in High-Rise Residential Buildings. Journal of Asian Construction Engineering and Management, Academic Annual Architecture and Building Engineering. 12 (1), pp.125-132. Conference Proceedings. 120 JAABE vol.14 no.1 January 2015 Jaeyoul Chun http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Asian Architecture and Building Engineering Taylor & Francis

QFD Model Based on a Suitability Assessment for the Reduction of Design Changes in Unsatisfactory Quality

Download PDF
8 pages

Loading next page...
 
/lp/taylor-francis/qfd-model-based-on-a-suitability-assessment-for-the-reduction-of-1a0peXHC8V

References

References for this paper are not available at this time. We will be adding them shortly, thank you for your patience.

Publisher
Taylor & Francis
Copyright
© 2018 Architectural Institute of Japan
ISSN
1347-2852
eISSN
1346-7581
DOI
10.3130/jaabe.14.113
Publisher site
See Article on Publisher Site

Abstract

When a design project is executed, inappropriate decisions in the selection of materials, construction methods, and systems negatively impact the productivity of the project since such decisions result in inadequate design. Subsequently, these defects become a cause for design changes. In order to prevent such cases, clear RPC (Requirement Performance Criteria) should be provided in order to allow for suitable design alternatives, and a quality review should be undertaken by tracking alterations in the requirements, as these continuously change and update. This study suggests a quality function deployment (QFD) model that is based on a suitability assessment (QFD-SA) to prevent design changes that result in unsatisfactory quality. The suggested assessment model is able to define the function and performance requirements, and it is thus suitable for use when selecting design alternatives for those requirements. The model uses a matrix technique in its assessment, and furthermore, the QFD-SA assessment model reanalyzes the degree of conformity according to the changes in the RPC. Keywords: QFD (Quality Function Deployment); design change; requirement; performance; suitability 1. Introduction requirement definitions and insufficient sharing of Design changes inevitably occur during the building information between project stakeholders were major design process. There can be a number of causes causes of design changes (Isacc and Navon 2008). for these design changes, including amendments in Design errors, missing functions, and alternative regulations, additional client needs, changes in the selection errors are among the various causes of design original requirements, design errors caused by the changes that can possibly be improved by quality designer, missing functions, and alternative selection management activities performed by administrators. errors. An investigation performed by the Procurement The above mentioned factors altogether represent Agency, which is the representative institution that the types of design changes that can occur and places design orders for domestic facilities, pointed out subsequently result in unsatisfactory quality, which that inadequate design and subsequent design changes means that there are inconsistencies in the work with are a major factor that negatively impacts facilities respect to the requirements of the design. In contrast, (Procurement Agency 2004). the additional needs of the clients and changes in the According to an investigation on the frequency of original requirements result in somewhat different flaws during the design review of apartment houses characteristics for the design work. These are situations and office buildings (Kwak and Kim 2010), alternative that occur due to uncertainty of design work and to selection errors and missing functions were the most the nature of collaborative work involving numerous frequent source of design defect. A lack of a usability stakeholders. review performed by the client, missing representations In conclusion, all of these factors are caused on the drawings, and discrepancies in the information by inadequate criteria for the requirements or by between the different construction works followed, discrepancy between the requirements and the design in that order. Another study indicated that insufficient solutions. Hence, the causes for design changes resulting from unsatisfactory quality may be classified into two categories: first, discrepancies between the *Contact Author: Jaeho Cho, Research Professor, required quality and that of the design solution; and Department of Architectural Engineering, Dankook University, second, vague descriptions of the RPC. Fig.1. below 152, Jukjeon-ro, Suji-gu, Yongin-si, Gyeonggi-do, shows a schematic of the types of design changes 448-701, Korea resulting from unsatisfactory quality, among the entire E-mail: cjhace@naver.com causes for design changes. As a result, clear criteria ( Received April 7, 2014 ; accepted October 30, 2014 ) Journal of Asian Architecture and Building Engineering/January 2015/120 113 should be presented with respect to the required quality suitability according to the RPC. (5) Validate the utility and the proper decision-making technique for an of the QFD-SA model by analyzing specific cases. (6) assessment of quality conformity should be performed Address the conclusions of this study. in order to reduce the number of design changes due to unsatisfactory quality. 3. Literature Review The existing research was surveyed and the themes of the relevant studies were divided into two categories: the 'study of design changes' and the 'study of decision making techniques'. (1) Study of Design Changes in Building Studies discussing design changes have been actively conducted both within Korea and abroad. With respect to domestic research, the majority of these have focused on performing environmental analyses of design changes, related policy issues, cooperative design methods, and quality management processes that prevent design changes. Ahmed et al. (2003) implemented a QFD model as an assessment tool to find alternatives to design changes and to keep track of the requirements requested by the owner. In addition, they suggested a new method to manage information on the Fig.1. Cause of Design Change Due to Unsatisfactory Quality requirements of the project as well as to communicate The fundamental concepts of quality management the process for the design changes. Oh (2007) analyzed are to define the requirements of the project and to the factors that could result in design changes in implement the design based on the requirements. construction projects, and suggested ways to improve An accurate and clear definition of quality is that the construction changes in the environment. Isaac and "Quality is conformity to the requirements." In 1979, Navon (2008) examined the causes for interruptions Phillip Crosby described the concept of quality in his that occur in functions specified in design changes, and work, 'Quality Is Free: The Art of Making Quality also proposed a tool for automated design changes that Certain'. allow users to trace relationships that exist between A comprehensive understanding of the 'required the given requirements and the design production. function', 'required performance criteria', and 'product This ensures that the stakeholders involved in the performance' is essential to effectively manage decision process, in which change proposals are quality. Hence, this study suggests a Quality Function evaluated, will know the scope of the implications Deployment based on a Suitability Assessment (QFD- of the change in advance. Kim et al. (2009) analyzed SA) model that defines the required function and the the main cause for design changes that have occurred RPC by using the QFD. Thus, this model allows for an during building construction and proposed a process assessment of the suitability of the design alternatives model that supports those design changes. Lee and by following the alterations in the requirements. The Chun (2012) also investigated design changes and suggested model can support users to make appropriate proposed a quantitative assessment method that could decisions, and prevent design changes by essentially handle alternative designs by taking into account cost, improving the causes of the design changes. performance, and constructability. Despite systematic approaches to the causes and problems of design 2. Methods and Ranges of Study changes that we have seen when discussing existing This study proposes a decision-making technique research, it was revealed that the proposal of a quality that is based on RPC for the assessment of quality assessment model were very rare in order to improve conformity and suitability, and undertaken by inadequate design and the proposals of processes in performing the following steps. order to improve unsatisfactory quality. (1) Evaluate the status of the existing research. (2) Study of Decision Making Techniques The themes of the research were categorized into Decision-making during the design process should two categories, including 'study of the reduction be undertaken with caution since the subsequent of the design changes' and 'study of the decision- phase directly affects the next phase. In particular, making technique'. (2) Determine the causes for the inappropriate decision-making during the planning design changes of an unsatisfactory quality type via phase and the schematic design phase results in various case investigation. (3) Propose a process for quality forms of productivity loss since those decisions management following alterations in the requirements. themselves become a direct cause of design changes at (4) Propose a quality assessment model based on the construction document phase or construction phase. 114 JAABE vol.14 no.1 January 2015 Jaeyoul Chun The Analytic Hierarchy Process (AHP), Forced- been suggested, a research theme has not yet found Decision Method (FDM)/Improved Weight Decision a conformity assessment and suitability assessment Method (IWDM), Weighted Comparison Matrix according to the RPC. method (WCM), VE-Matrix Evaluation Method, and QFD are decision-making techniques that are broadly 4. Analysis of the Causes of Design Changes due to utilized in both industry and academia. Unsatisfactory Quality Lee and Chun (2009) utilized the FDD/IWDM Design changes are caused when a design is not method to evaluate the alternatives. The features of the suitable for any of the project requirements in terms FDD/IWDM method are that the relative priorities of of the schedule, cost, or quality. In addition, design the function can be evaluated. change factors exist over the entire scope of the The VE-Matrix Method uses a rating scale for construction project, such as alterations in the client's linguistic assessment (Caltrans Value Analysis Report requirements, amendments to the regulation systems, Guide, 1999). In this scale, the function ideas are and a diversification of the construction methods. evaluated by using a 10-point rating scale. The VE It is impossible to conduct perfect schematic Matrix Method allows users to evaluate performance design and design development that does not involve and to set the priorities of the functions. Users can design changes. Table 1. below shows the results of then set the evaluation items, such as the degree of investigation on cases of design changes based on 26 satisfaction of the function, constructability, and cases of private office buildings. economic feasibility. The VE Matrix Evaluation The factors that cause design changes can be method is then used to choose the optimal alternatives categorized by items and by operating organization. by estimating the priorities of each of the evaluation The operating organizations that cause design changes items, and as a result, this method is suitable for a have been revealed as designers in the first place, comparison of the quality of the design alternatives. clients in the second place, and contractors in the In addition to the three methods mentioned above, third place. The items that cause design changes are QFD is has also been considered as a representative shown as 'changes in schematic design' first, 'material method for decision-making. The QFD method is a changes and quantity growth' and 'ambiguous design quality assessment method that can be widely used in and missing function' second, and 'inconsistency in industry, and it was created by Mitsubishi in 1972. design solution based on field conditions' and 'client's This method analyzes the function and the additional requirements' third. performance that comprise quality by converting This study does not present the representative causes the client's requirements into a design quality for all design changes, but only provides a rough list definition. The components of the QFD are the of the causes. The results shown in Table 1. allow us client's requirements, extraction of quality factors in to deduce the design changes that were caused with the requirements, estimation of the priorities in the respect to quality. required quality, and a weighting priority conversion. The change types, including schematic designs, Kwak (2011), Yoo and Yi (2005), and Yang and Kim fluctuations in quantity, civil complaints, and (2005) used QFD to perform a quality assessment. unpreventable natural disasters are natural phenomena Prasad (2013) evaluated product quality in terms of that are caused by uncertainty, which is part of the performance for each design alternative by using QFD. nature of architectural design. Improvements in the Quality evaluation system proposed by Prasad (2013) design quality, including changes from such causes, is a representative case utilizing QFD. Li et al. (2014) require different approaches. However, the types proposed a new method of multi criteria decision- including 'ambiguous design', 'missing function', making by combining QFD and TOPSIS evaluation and 'selection error of the construction methods' models. Many other studies on the QFD method are considered as the type of design changes that have been presented, and case studies of specific are a result of unsatisfactory design. These, in turn, applications are continuously in progress. are caused when the quality of the design does not QFD has strengths and weaknesses as follows. meet the necessary quality threshold, or when the The QFD method creates a novel idea, mainly by requirements are not clearly defined. The 'inconsistency considering the performance priorities for quality and with field conditions' item is another cause for design by focusing on quality improvements. While the RPC changes that are due to unsatisfactory quality, and it may be defined by the QFD, the degree of suitability is highly related to the 'interference among building of quality based on the RPC may not be evaluated. As system functions', 'function errors' and 'performance we have discussed, research related to the decision- discrepancies'. making techniques discussed above have revealed that The following issues should be reviewed in order to decision-making techniques are able to assess the value reduce the occurrence of such items. scores by focusing on function. ① Check if the design alternatives show conformity Although several methods for a quantitative to the required performance criteria of the field project. evaluation of the function and the performance have JAABE vol.14 no.1 January 2015 Jaeyoul Chun 115 ② Check if the performance of the design alternatives interferes with that of adjacent systems. ③ Check if there are self-contradictions between the functions of alternative design. Fig.2. shows the concept diagram of the quality suitability and the causes for design changes of an unsatisfactory quality type. Fig.3. Concept of Quality Assessment upon the Changes Therefore, a quality assessment process that prevents design changes can be performed with the following 4 steps: (1) Setting the function priority and the agreed definition of the required functions by the project stakeholders. (2) Setting the relationships associated with the required functions and the RPC. (3) Verification of the contradictory function and the interference of the RPC. (4) Review of the conformity and suitability of the quality between the design Fig.2. Design Change in Quality Dissatisfaction alternatives and the requirements. 5. Quality Management Process Based Upon Changes in Requirements 6. QFD Model based on Suitability Assessment Clear definitions of the required functions are The 'QFD-SA' method adopts the CVAG (Caltrans essential for the selection of design alternatives since Value Analysis Guide, 1999) linguistic assessment. each project has unique characteristic and properties. A 5-point Likert scale is used to assess the function In addition, changes in the required function and in the priority. RPC frequently occur as a result of the innate nature of The QFD-SA method and the QFD method share the design process. a common feature for defining the relevance of the The RPC is redefined during a mutual review performance items related to function. The QFD-SA process by experts from each design discipline, method differs from the QFD method in respect of and these are continually revised during the design suitability against the RPC. process. Therefore, the assessment of conformity The RPC m ay be defi ned as the minim um and the suitability of the design alternatives should performance values or as the recommended be performed in an environment with continuously performance values. These criteria are related to changing requirements. A concept diagram of the functions that are utilized in the assessment of the design quality management for the changes in the conformity and the suitability through a comparison requirements of each phase of the design process is with the given RPC. A concept diagram of the shown below in Fig.3. suitability assessment is presented in Fig.4. Since changes in the requirements also alter the The suitability scale is '0' when the required RPC, technical decision-making is required to solve performance criteria are the same as the performance conflicts with existing systems and interference of the alternatives; and a zero value is used for strict between the requirements. conformity. For example: if the performance value of Table 1. Analysis of the Factors Concerning Design Changes (The 26 Cases of Office Buildings) Item Causes of the Design Changes Owner Designer Contractor Frequency Ranking Relation 1 Additional Client's Needs 10 - - 10 3 Quality 2 Selection Error of Construction Methods - - 9 9 4 Quality 3 Material Changes, Quantity Growth 5 - 7 12 2 Quality 4 Inconsistencies in the Design and the Field - 10 - 10 3 Quality 5 Inadequate Schematic Design - 8 - 8 5 Quality 6 Change in the Schematic Design (Volume of 12 14 - 26 1 Quality Space) 7 Unclear Design, Missing Features, Design Errors - 12 - 12 2 Quality 8 Omission of Construction Statement (bill) Item - - 8 8 5 Cost 9 Civil Complaints 4 - 2 6 7 - 10 Safety Assurance - 7 - 7 6 Quality 11 Unpreventable Natural Disasters 2 1 2 5 8 - 116 JAABE vol.14 no.1 January 2015 Jaeyoul Chun rd nd the alternative is higher than the RPC by a score of 2 score of 4, the 3 rating a score of 3, the 2 rating a score st in the performance ratings, then the suitability score is of 2, and the 1 rating a score of 1. In the case where the 2. If the performance value of the alternative is higher performance evaluation for the alternatives is either a than the RPC by a score of 1, then the suitability nominal rating or a binary rating, such a scale readjusts to score is 1, if the performance value of the alternative the corresponding rating to provide a normalization score. is equivalent to the minimum performance, then the ④ Correlation Analysis of Function and Performance suitability score is 0, if the performance value of the (CAFP): The correlation between the function and the alternative is lower than the RPC by a score of 1, then performance is evaluated. For example, an extremely the suitability score is -1, and if the performance value high correlation (●) has 1 point, a high correlation (○) of the alternative is lower than the RPC by a score of 2, has 0.8 points, a moderate correlation (▲) 0.6 points, then the suitability score is -2, etc. and a low correlation ( ▽ ) 0.4 points. The scale of the correlation is not absolute, and the user can choose among various scales. ⑤ Satisfaction Analysis for Required Performance Criteria (SARPC): Review the quality satisfaction through a comparison of the RPC that are specified in the design guidelines and the performance grade of the product alternative. Dissatisfaction mark (▲) is presented. And satisfaction mark (● ) is presented. ⑥ Interference Analysis for Required performance Criteria (IARPC): One value of the RPC is set as the standard, and an interference mark ( △ ) is presented, when the RPC differ from one another. If no interference occurs, it is presented with (-). ⑦ Function Satisfaction Analysis (FSA): Review the function satisfaction through a comparison with the required performance criteria. FSA is determined, Fig.4. Conceptual Diagram of Conformity and and Suitability when the suitability score is the same as, or higher than In the case of the other scales, such as the nominal 0 point. The function satisfaction is presented with scale or the binary scale, the suitability scale is also ( △ ). Function dissatisfaction is presented with (○ ). readjusted according to the normalization of the zero ⑧ TFSS (Total Function Suitability Score): Assign rating point. Fig.5. presents the basic format of the the suitability scores by comparing the performance 'QFD-SA' method. values of the product. TFSS (Total Function Suitability Score: V) for the design alternatives are estimated by summing up the FSS. Fig.5. QFD Concept Model-based on a Suitability Assessment ① Function Definition (FD): The process for defining a function is proposed in the literature and is ⑨ SIUL (Suitability Index based on Unsatisfactory ... (1) related to VE and the 'FAST Diagram' method. The Level): This value is the sum of the FSS that are less defining function in this study shows only the detailed than 0 divided by the absolute maximum total of definition of the function. SUSS. ② Function Weight (FW): The function weight is ……………………..……... (2) ... (1) determined by using a 10-point scale. For example: maximum priority = 10 points, moderate priority = 5 points, minimum priority = 1 point. …………..….…………..……... (3) ③ Performance of Design Solution (PDS): The ……………………..……... (2) performance is evaluated and classified into 5 ratings. th th For example: the 5 rating is a score of 5, the 4 rating a ..….…. (4) …………..….…………..……... (3) JAABE vol.14 no.1 January 2015 Jaeyoul Chun 117 ..….…. (4) ……………………..……... (5) ……………………..……... (6) ……………………..……... (5) ….…… (7) ……………………..……... (6) .……. (8) ….…… (7) .……. (8) .……. (9) ... (10) .……. (9) ... (10) ... (1) ……………………..……... (2) ... (1) ⑫ FCD (Function Conformity Deviation): The FCD …………..….…………..……... (3) is obtained by calculating the distance between the ……………………..……... (2) SIUL and the SISL. The Sub-Function Conformity Deviation (SFCD) is the distance between the USIF SISL (Suitability Index based on Satisfactory and SSIF. ..….…. ... (1) (4) level): This value is the…………..… sum of the .… suitability ………..…… scores ... (3) that are greater than 0 divided by the maximum total of 7. Case Study SSSS. In order to verify the validity of the 'QFD-SA' method, the suitability was evaluated for the required ……………………..……... (2) ……………………..……... (5) ..….…. (4) function that was initially planned, and then it was compared against the suitability of the required function that was altered. ……………………..……... (6) …………..….…………..……... (3) (1) Summary of the Case Study ……………………..……... (5) The QFD-SA technique can be applied to window desi gn. Windows are expected to have several ….…… (7) characteristics, such as insulation performance (Heat ..….…. (4) ……………………..……... (6) Transmittance: U Value), Solar Heat Gain Coefficient (SHGC), Visible Light Transmittance (VT), Air .……. (8) Leakage (AL), Condensation Resistance (CR), TFCI (Total Function Conformity Index): This and Outdoor Indoor Transmission Class (OICT). ……………………..……... (5) ….…… (7) value is the estimated CSS divided by the maximum Thermal comfort in spaces (a required function) can SSSS or the maximum SUSS. For the negative sums of be determined by the complex performance of these .……. (8) CSS, the estimated CSS are divided by the maximum features. Window performance and the standard rating ……………………..……... (6) SUSS. For the positive sum of CSS, the estimated CSS grades that have been analyzed are summarized below .……. (9) are divided by the maximum SSSS. in Tables 2. and 3. Table 2. Performance Value of the Alternative Design Solutions ….…… (7) ... (10) Solutions U-Value SHGC VT AL CR OITC 0.49 0.33 0.55, 0.20 71 32 Alt-(1) .……. (9) .……. (8) (Gr.3) (Gr.4) (Gr.3) (Gr.4) (Gr.4) (Gr.4) 0.38 0.48 0.35, 0.25 30 27 Alt-(2) (Gr.4) (Gr.3) (Gr.2) (Gr.3) (Gr.2) (Gr.2) ... (10) 0.47 0.52 0.50, 0.24 58 27 Alt-(3) (Gr.3) (Gr.2) (Gr.3) (Gr.3) (Gr.3) (Gr.2) 0.31 0.46, 0.55, 0.36 49 35 Alt-(4) (Gr.4) (Gr.3) (Gr.3) (Gr.2) (Gr.3) (Gr.4) .……. (9) Table 3. Performance Utilizing a 5-Point Rating Scale Grade-5 Grade-4 Grade-3 Grade-2 Grade-1 Performance (score 5) (score 4) (score 3) (score 2) (score 1) ... (10) U-factor 0.00 ~ 0.20 0.20 ~ 0.40 0.40 ~ 0.60 0.60 ~ 0.80 0.80 ~ 1.00 SHGC 0.20 ~ 0.30 0.30 ~ 0.40 0.40 ~ 0.50 0.50 ~ 0.60 0.60 ~ 0.70 VT 1.00 ~ 0.80 0.80 ~ 0.60 0.60 ~ 0.40 0.40 ~ 0.20 0.20 ~ 0.00 AL 0.00 ~ 0.10 0.10 ~ 0.20 0.20 ~ 0.30 0.30 ~ 0.40 0.40 ~ 0.5 CR 100 ~ 80 80 ~ 60 60 ~ 40 40 ~ 20 20 ~ 0 OICT 40 ~ 36 36 ~ 32 32 ~ 28 28 ~ 24 24 ~ 20 Fig.6. The Case Analysis of the QFD-SA for Alternative (1) 118 JAABE vol.14 no.1 January 2015 Jaeyoul Chun The RPC is defined to comply with the design (1) is based on the alterations in the requirements that guidelines for the characteristics of insulating windows were revealed in the SIUL function as -0.13. The SISL in the North-central United States, which has a similar was obtained as +0.04. The TFSS was -11.29. The climate to Korea (i.e. mixed hot and cold climates). TFCI for Alternative (1) was evaluated as -0.16, and (2) QFD-SA Case Study based on the Definition of the FCD of the alternative was calculated as 0.17. the Original Function (4) Discussion of the Analysis Fig.6. shows a case of the function assessment for Once the RPC are determined, the FCI is obtained Alternative (1) based on the QFD-SA method. The SIUL according to the performance value of the design was evaluated as -0.09 in the analysis of Alternative (1). alternatives. A closer FCI, TFCI consists of 0 points, The SISL was revealed to be +0.09, and the TFSS which is the greatest conformity that can be achieved was obtained as 0.49. The TFCI for Alternative (1) was with respect to the required function. Also, the higher the calculated as 0.01, and the FCD for Alternative (1) was FCI and TFCI, the greater the satisfaction with respect calculated as 0.18 (0.09-(-0.09)). to the required function that is thought to be obtained. (3) A Case of the QFD-SA Analysis based on the Although the design alternative shows a high value for Definition of the Changed Function TFCI, the alternative is considered to be unsuitable in The requirements are changed based on the RPC. the design if an SIUL arises to some extent. Alterations in requirements occur due to the client's Therefore, both the TFCI and the SIUL should be additional request concerning improvement in thermal considered for proper selection of an alternative. Fig.7. insulation performance and reduction in cooling load presents the results of a QFD-SA analysis based on during summer time. The following 4 changes were the definition of the original requirements for 4 design made in the function. alternatives, and the changes in the requirements for ① Change in the FW: function 1 (from 4.3 to 6.2), the 4 design alternatives, respectively. function 5 (from 4.8 to 7.8), and function 8 (from 4.3 For QFD-SA based on the original definition, to 8.0). ② U-Value performance ratings for function 'Alternative 1' recommends the proper design that shows rd 1 and function 5: Changed from the 3 rating to the the minimum SIUL of -0.09 with the TFCI of 0.008 (about th 4 rating. ③ SHGC performance rating for function 0.01). On the other hand, 'Alternative 4' shows the SIUL th th 1: Changed from 4 rating to 5 rating. (Grade 5 of of -0.16 with the TFCI of 0.014 (about 0.01). SHGC performance reduces energy cost by blocking For the QFD-SA based on the change definition, more solar heat compared to Grade 4.) ④ AL rating for 'Alternative 1' is recommended as the proper design function 1, function 5, and function 8: Changed from alternative, which shows the SIUL of -0.13 with the rd th 3 rating to 4 rating. TFCI of -0.16. 'Alternative 1' has the minimum SIUL The QFD-SA analysis is performed again according of -0.13 and the highest TFCI of -0.16. to the changes in the RPC. The analysis for Alternative In conclusion, the decision makers are not able to Fig.7. TFCI and SIUL/SISL of Alternative Designs by the QFD-SA JAABE vol.14 no.1 January 2015 Jaeyoul Chun 119 4) Cho, K.M. (2014) Evaluation of Technologies Ensuring Green clearly recognize an SIUL if the QFD-SA analysis is Performance in Multi-family Housing Projects in Korea. Journal of not performed by defining the RPC. The absence of Asian Architecture and Building Engineering. 13 (1), pp.133-139. an objective evaluation standard may result in a defect 5) Crosby P. (1979) Quality Is Free: The Art of Making Quality in the decision making with the selection of design Certain. McGraw-Hill Companies 1st edition. 6) Isaac, S. and Navon, R. (2008) Feasibility Study of an Automated alternatives. Unsatisfactory function with respect to the Tool for Identifying the Implications of Changes in Construction RPC is a major cause of design changes. Projects. Journal of Construction Engineering and Management, 134 (2), pp.139-145. 8. Conclusion 7) Jeong, J.S., Ryoo, I.W., and Lee, Y.W. (2006) A Study on the Choice of the Curtain-Wall Type and the Exterior Material These Design changes of an unsatisfactory quality are according to Commercial Building Images by using the AH, Korea caused by ambiguous requirements and by insufficient Institute of Construction Engineering and Management (Planning), quality assessments. A clear definition of the required 22 (11), pp.89-96. 8) Jung, J.H. and Lee, H.K. (2011) A Study on the Analysis of Contract function should be obtained, first of all, in order to Changing Situation for Public Construction Project. Regional secure the quality required, and thus prevent additional Association of Architectural Institute of Korea, 13 (04), pp.315-322. design changes. A clear recognition of the requirements 9) Kang, H.J. and Rhee, E.K. (2014) Development of a Sustainable and the implementation of the assessment based on Design Guideline for a School Building in the Early Design Stage, Journal of Asian Architecture and Building Engineering. 13 (2), the RPC allow for a significant reduction in the design pp.467-474. changes that occur due to unsatisfactory quality. 10) Kim, S.W., Nam, H.W., Lee, J.S., Shin, C.H., and Chun, J.Y. The QFD-SA quality assessment model that is (2009) Case Survey and Analysis for the Proper Design Changes proposed in this study supports assessments for the Management. Architectural Institute of Korea, Academic Annual Conference Proceedings. conformity and suitability of design alternatives, 11) Kwak, C. (2011) Study of the Method of Analysis for Main Causes according to the RPC. The QFD-SA method provides of Design Quality Declining using QFD in Construction Projects. a quantitative evaluation of the quality satisfaction Master's thesis, Sungkyunkwan University. for function and performance that design alternatives 12) Kwak, C. and Kim, Y.S. (2010) Building the Model of Analysis for the Main Causes of Design Quality declining in the Construction have. The following are the improvements of the QFD- Projects. Korea Institute of Construction Engineering and SA method in terms of the definition, analysis, and the Management, Academic Annual Conference Proceedings. evaluation of quality. 13) Lee, J.S. and Chun, J.Y. (2009) Risk Response Analysis Model (1) It allows for a reflection of both the definition of the for Construction Method Using the Forced-Decision Method and Binary Weighting Analysis. Journal of Asian Architecture and required function and alterations that the client intends. (2) Building Engineering, 8 (1), pp.205-212. It allows for an evaluation of the priority of the function, 14) Lee, J.S. and Chun, J.Y. (2010) Decision Making Process for and that of the related performances. (3) It allows for Alternative Selection of Proper Design Change in Construction Project. Korea Institute of Construction Engineering and an investigation of the self-interference between the Management, 11 (2), pp.74-81. performances of the required function in advance. (4) It 15) Lee, J.S. and Chun, J.Y. (2012) A Numerical Value Evaluation allows for an analysis of the conformity and suitability Model for the Optimum Design Selection. Journal of Asian of the design alternatives based on the RPC. (5) It Architecture and Building Engineering, 11 (2), pp.283-290. 16) L e e , K. I. , Ye om D.W. , a n d Ki m , E . J. ( 201 3) E xp e ri m e n t a l allows for the management of the suitability range of the Research on the Correlation of Temperature, Humidity, and CO quality by calculating a SIUL and SISL. (6) It allows for Level of a Rice Hull Insulated Indoor Environment, Journal of maintaining the user's goals by re-assessing the quality. Asian Architecture and Building Engineering. 13 (2), pp.221-217. A future study aims to investigate the broader 17) Li, M., Jin, L., and Wang, J. (2014) A new MCDM method combining QFD with TOPSIS for knowledge management utilization of QFD-SA by adopting it on a compound system selection from the user's perspective intuitionistic fuzzy scale that consists of a nominal scale, a binary scale, environment. Applied Soft Computing, 21, pp.28-37. etc. In addition, an assessment system for design 18) Oh, B.S. (2007) Study on the Analysis about Causes of Change quality that can be utilized in a web environment will based on Case Analysis of Construction Project on the Site. Seoul National University of Science and Technology, Master's thesis. also be developed. 19) Oh, Y.K. (2014) An Assessment Model for the Indoor Noise Environment of Aged Apartment Houses, Journal of Asian Acknowledgements Architecture and Building Engineering. 13 (2), pp.293-300. This research was supported by the National 20) Prasad, K. and Chakraborty, S. (2013) A Quality Function Deployment-based Model for Materials Selection. Materials and Research Foundation of Korea (NRF) (No. NRF- Design, 49, pp.525-535. 2012R1A1A2043186). 21) Procurement Agency (2004), Design Management Business Handbook. 22) Song, Y.W., Park, J.C., Chung, M.H., Choi, B.D., and Park, J.H. References (2013) Thermal Performance Evaluation of Curtain Wall Frame 1) Ahmed, S. M., Sang, L. P., and Torbica, Z. M. (2003) Use of Types, Journal of Asian Architecture and Building Engineering. 12 Quality Function Deployment in Civil Engineering Capital Project (1), pp.157-163. Planning. Journal of Construction Engineering and Management, 23) Yang, J.K. and Kim, S.Y. (2005) Improvement and Systematization 129 (4), pp.358-368. of Pre-Study Work for Design Value Engineering in Construction 2) Caltrans VA Report Guide 1999. State of California Department of Projects by Quality Function Deployment. Korea Institute of Transportation. Construction Engineering and Management, 6 (4), pp.122-129. 3) Cho, G.Y., Yeo, M.S., Kim, K.W. (2013) Design Parameters of 24) Yoo, S.Y. and Yi, J.S. (2005) A Basic Study on the Application Double-Skin Façade for Improving the Performance of Natural of QFD at Architectural Design Phase. Korea Institute of Ventilation in High-Rise Residential Buildings. Journal of Asian Construction Engineering and Management, Academic Annual Architecture and Building Engineering. 12 (1), pp.125-132. Conference Proceedings. 120 JAABE vol.14 no.1 January 2015 Jaeyoul Chun

Journal

Journal of Asian Architecture and Building Engineering – Taylor & Francis

Published: Jan 1, 2015

Keywords: QFD (Quality Function Deployment); design change; requirement; performance; suitability

There are no references for this article.