Using TRIZ to Improve Maintenance and Repair Services at Jung-xian

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1 Using TRIZ to Improve Maintenance and Repair Services at Jung-xian Auto Repair 1 Tai-Chang Hsia, 2 Ling-Bo Pu *1 Department of Industrial Engineering and Management, Chienkuo Technology University Changhua, Taiwan, tchsia@ctu.edu.tw 2 School of Management, Jiangsu University Zhenjiang, Jiangsu, pulingbochina@gmail.com Abstract Jung-xian Auto Repair is located in central Taiwan and focuses on imported vehicles. This research designs a quality system to improve maintenance and repair services. This system uses a systematic, step-by-step improvement approach. Four steps were used to complete the quality system. First, we define customers acceptance levels (including importance and satisfaction in two dimensions) toward Jung-xian s car service quality. A questionnaire survey is constructed and a performance matrix of service quality is created. These measure the service items that are of low importance but high satisfaction, as well as items of high importance but low satisfaction. These are key items for improvement. Second, in this study a Cause & Effect Diagram is used to analyze the abnormal service items and list the concrete service strategies. Then a Quality Function Deployment Table is applied to define key service strategies for improvement. Finally, we apply the TRIZ innovation method to construct a quality system to improve maintenance and repair services. 1. Introduction Keywords: Maintenance and Repair, Systematic Innovation, TRIZ Innovation Service quality measurement is an important area of research. Many researchers agreed and proposed some methods to measure service quality [4,9,10,11]. However, no specific action was taken to improve consumer feelings. Thus, this research designs a quality system using Systematic Innovation method and applies a step-by-step process improvement approach for Jung-xian Auto Repair to enhance their service quality of maintenance and repair. Jung-xian Auto Repair, located in central Taiwan, provides maintenance and repair services for imported cars like Audi and KIA. This study first conducted a questionnaire of acceptance levels (including importance and satisfaction) for the Auto Repair and formed a service quality performance matrix according to the results from the questionnaire to find the key items. Second, this study used a cause & effect diagram to analyze those abnormal service items and list the concrete service strategies. Third, a quality function deployment table was applied to define key quality service strategies. Finally, TRIZ was used to construct a quality system to improve maintenance and repair services. 2. Defining satisfaction index and importance index in quality service Following Lambert and Sharma[7] and Parasuraman et al.[9,10], we used the questionnaire to investigate two dimensions of service quality, importance and satisfaction. The results are presented as the following two indices. The service quality importance index I SI = SI min (1) R The service quality satisfaction index min I SS = SS (2) R Where, the two indices, μ SI and μ SS, respectively refer to the mean of the consumers service quality Advances in information Sciences and Service Sciences(AISS) Volume5, Number9, May 2013 doi: /aiss.vol5.issue

2 satisfaction (SI) and service quality satisfaction (SS) and min refers to the minimum value in the k-point scale. Min is usually set to 1 (min=1). R=k-1 refers to the range of k-point scale. To explain the two above indices, we use the service quality importance index (I SI ) as an example. The value of the four indices lies between 0 and 1, inclusively. When I SI =0 (i.e. μ SI =1), in the consumers point of view, the service quality is not important at all. The importance level is 0%.When I SI =0.5 (i.e. μ SI = (k+1)/2), the service quality is moderately important. The importance level is 50%.When I SI =1.0 (i.e. μ SI =k), the service quality is highly important. The importance level is 100%. The values of the two indices above all lie between 0 and 1. We use the importance index and the satisfaction index to explain consumer evaluations of the service quality of the Auto Repair. We use a 5-point interval-scale questionnaire (k=5, very important, important, neutral, not important, not at all important). If the mean of the service importance index for a certain service is higher than 3 (neutral), it indicates that the importance index of that service exceeds 0.5. If the mean of its service satisfaction index is lower than 3, its satisfaction index is lower than 0.5. From the service viewpoint, if the importance index is higher than the satisfaction index, customers expect that the service will increase to a point at least equal to or greater than the importance index. Conversely, when the satisfaction index is higher than the importance, customers feel that the service satisfaction can be reduced to save cost. To understand the evaluation of service quality from both the consumer and service viewpoints, one useful instrument is the performance evaluation matrix. Hung et al.[4] and Lambert and Sharma[7] have proposed the performance matrix in which the values of the satisfaction index and the importance index both lie between [0.0, 1.0]. Additionally, the horizontal axis and the vertical axis of the matrix are divided into four scales [0.0, 0.33, 0.67, 1.0] and three ranks, defined as low (between 0.0 and 0.33), middle (0.33 to 0.67), and high (0.67 to 1.0). The three by three matrix thus contains nine cells. When the scores of the importance index and the satisfaction index fall between [0.0, 0.0] and [0.33, 0.33], service quality possesses neither importance nor satisfaction. When the scores fall between [0.67, 0.67] and [1.0, 1.0], service quality has importance and satisfaction. When the scores fall between [0.33, 0.33] and [0.67, 0.67], service quality is neutral with respect to importance and satisfaction. The three cells discussed above contain a similar level of importance and satisfaction and thus are called target cells. This study applies the performance matrix proposed by Hsia et al.[5] to carry out the evaluation of product quality and service quality. We draw a diagonal which is the target line for quality importance and satisfaction between [0.0, 0.0] and [1.0, 1.0] in the Performance Matrix. When the score of both the importance index and the satisfaction index lie on this line, it means the service quality is at the most appropriate level. When the score falls to the right of the target line, it indicates that satisfaction exceeds importance, implying that the service quality can be reduced without loss of customer satisfaction. When the score falls above the target line, importance exceeds satisfaction, meaning that resources should be increased in order to properly enhance service quality. For more efficient control, two control lines have to be set in the matrix: the Upper Control Line (UCL) between (0, a) and (1-a, 1) and Lower Control Line (LCL) between (a, 0) and (1, 1-a). The rigorousness with which these lines are defined (i.e. the value of a ) depends on the company policy, the enterprise standard, and competitors. In the current study, since the matrix was divided into three equal performance zones, the value of a must be set to In this Performance Matrix, the line connecting (0.0, 0.184) and (0.816, 1.0) is the Upper Control Line while the line connecting (0.184, 0.0) and (1.0, 0.816) is the Lower Control Line. The zone between the Upper and Lower Control Lines is the target zone A, in which the service quality importance and the service quality satisfaction are close. The zone between the Lower Control Line and (1.0, 0.0) is labeled the Resources Overloaded Zone D, where service quality satisfaction is higher than importance, while the zone between the Upper Control Line and (0.0, 1.0) is called the Resources Lacking Zone I, in which the service quality importance exceeds satisfaction (Figure 1). 410

3 Figure 1. Performance matrix distributed in A, D, and I, three performance zones 3. Constructing a service quality questionnaire This study constructed 20 service items in accordance with the services provided by the maintenance staff for the customers who have had their car maintained or repaired from the car company, as shown in the fields of service items of the service quality questionnaire about satisfaction and importance indexes in Table 1. Customers are required to evaluate these service items according to importance and satisfaction. If the customers think there is greater agreement between the service items and their self-perceptions of satisfaction is more accurate, it means the customers feel this service item is more important. The smaller the gap between the service item and the customer satisfaction level, the more acceptable it is to customers and the more satisfied they will be (Table 1). Table1. Service quality questionnaire about satisfaction and importance indexes Item Service Item μ SI μ SS I SI (y i ) I SS (x i ) 1 When you enter the car company, the receptionist will serve you immediately and take down your requests in detail. What do you think? 2 When your car is undergoing maintenance or repair, the car company will generate a work order and illustrate this maintenance or repair item for you clearly. What do you think? 3 When you enter the car company, have you found enough space for the maintenance staff to perform repairs? When your car is under maintenance or repair, the company will send the specialists into the specialized service area and movement in the areas is unimpeded. The environment is clean and tidy. What do you think? 5 When you enter the car company, do you think that the air quality is good? Before your car s maintenance or repair, the service staff will notify you of expensive repairs and ask permission to carry out these service items. What do you think? 7 Before your car s maintenance or repair, the service staff will put dust covers on the interior and exterior to keep your car clean during the service process. What do you think? 8 When you enter the car company, the service staff will do a general check (on items such as chassis, tires, wipers, lights) for your car in addition to the maintenance or repair. What do you think? 9 When a staffer performs maintenance or repair, if he finds that something is not working, he will try to repair the broken item instead of replacing it with a new one. What do you think? 10 If the items which need to be maintained or repaired are under warranty, the car company will service the items for free. What do you think? 11 The car company replaces an item with the more expensive one which comes from the original company instead of the cheaper one

4 from a third party. What do you think? During the maintenance or repair, the staff will contact you if the service is not covered by the warranty. What do you think? When your car is undergoing maintenance or repair, if the staff cannot find the problem with your car, the delivery will be delayed. What do you think? What do you think if the car company is promoting quality certification and will soon be certificated by ISO? When your car is undergoing maintenance or repairs, are you comfortable with the staff s skills? What do you think? The staffs in the car company all have certification from the original company to ensure the specifications of the maintenance or repair. What do you think? The car company will inform you of any event they hold. What do you think? When your car is undergoing maintenance or repair, if you have any questions, the staff will patiently answer you and frequently update you about the status of the car. What do you think? When you are waiting in the rest area, the indoor soundproof will protect the area against noise from the maintenance area. What do you think? When the maintenance or repair is done, do the maintenance staff illustrate the maintenance or repair process and retain the old items for the car owner with the reason for the damage in order to ensure that the maintenance or repair is absolutely transparent? Investigation of service importance and service quality satisfaction This study conducts an investigation into service quality at Jung-xian Auto Repair by using questionnaires. Each item is ranked on a 5-point interval-scale questionnaire (k=5). Consumers were asked to rank the service importance and the service satisfaction of these service items. Two hundred questionnaires were distributed and returned, with 90 valid, for an effective rate of 45%. We first examine reliability. Test reliability means that the test will not be affected by the time or situation and the results are stable and consistent. It is estimated by the internal consistency. After designing the questionnaire, a pilot test for reliability analysis was performed. The Cronbach s α of the results of the pilot test exceed Thus, we need to carry out a test of reliability analysis again after all the questionnaires are returned. Cronbach s α is a generally accepted measure of internal reliability. In Gay s opinion[3], an α coefficient of 0.80 and above is acceptable, while 0.90 and above indicates a very high reliability, while De Vellis[2] and Nunnally[8] considered an α coefficient of 0.70 and above to be the minimum reliability value. In this study, Cronbach s α for the 90 valid questionnaires is over Next, based on the survey results, μsi and μss, the means of service quality importance (SI) and service quality satisfaction (SS) were calculated. Then, ISI and ISS, the values of the service quality importance and service quality satisfaction indices were calculated using the mean from Formula (1) and Formula (2), as shown in Table 1. Following the Performance Matrix described by Hsia et al.[5], a service quality performance matrix was constructed based on the values of the service quality importance index (ISI) and the service quality satisfaction index (ISS) shown in Figure 2. The service quality performance matrix can be used to evaluate the service quality of the different service items offered by Jung-xian Auto Repair. 412

5 Figure 2. Service quality performance matrix In the service quality performance matrix in Figure 2, the plots of the importance and satisfaction of the different service items show that 3 out of 20 service items are not located in the Target Zone (Zone A) and should be considered problem items. Service Items 9 parts should be repaired instead of replacement of the whole set and 20 maintenance or repair should be transparent are located in the Resources Lacking Zone (Zone I), while Service Item 17 regular events held by company is located in the Resources Overloaded Zone (Zone D). These three service items not located in the Target Zone are services that need to be enhanced. The priority of improvement needs to be determined against the service which needs to be enhanced. We prioritize improvement of the defective services according to the plots of the importance and satisfaction indices in the service quality performance matrix. The top priority is to improve the services located in the Resources Lacking Zone (Zone I), because customers have indicated that their importance is greater than their associated satisfaction; that is, these services are unsatisfactory. When the services appear in the Resources Zone (Zone D), consumers are, in a sense, overly satisfied with them, because their satisfaction ratings are higher than their importance ratings. Hence, these services are assigned secondary priority. If two or more defective services appear in Zone I or Zone D, the order of priority is determined as follows. Based on the concepts of performance evaluate matrix, the farther a service item falls from the target line, the more important it is to adjust the service. This distance of the service item from the target line is called the improvement index, represented by δ i. This study uses δ i to determine the order of priority for changing the defective services. The value of δ i always lies between 1 and -1; a positive value indicates the product service lacks resources, while a negative value implies it has too many resources. In either the Resources Lacking Zone or the Resources Overloaded Zone in the service quality performance matrix, the greater the absolute value of δ i, the greater its priority for improvement. This is clarified in Formula (3): δ i = y i - x i (3) Where, y i represents the importance index of the defective product or service, i = 1,, n; and x i refers to the satisfaction index of the defective product or service, i = 1,, n. We use Service Items 9 and 17 as examples. The importance and satisfaction indices of Service Item 9 lie within the Resources Lacking Zone I in the matrix (f(x, y) = (0.32, 0.75), δ 14 = 0.43), and the value of δ i is positive. This service thus needs to be improved. The service importance and satisfaction indices of Item 17 fall within Resources Overloaded Zone D (f(x, y) = (0.85, 0.20), δ 6 = -0.65), with a negative δ i value, indicating that resources may be reduced. 5. Finding the critical service strategies through analysis services needing enhancement There are two ways to treat services which need to be enhanced in the analysis: each service may be regarded as a separate unit, or, the defective services may be treated together and improved simultaneously. Determining which approach to use depends on whether each defective service item can be measured independently or is related to the overall service quality. In this study, since we made 413

6 a 20 item questionnaire to investigate customer satisfaction with the car repair company, we argue that the service items which need to be enhanced should be analyzed together. We construct a Cause-and-Effect Diagram for our analysis of the three service items which need to be enhanced and 10 specific service strategies (A-J) for enhancing service quality. Figure 3. Cause-and-effect diagram for enhancing service quality characteristics There is an overall service dependency between the 10 specific service strategies and the three items which need to be enhanced. Thus, we carry out a Quality Function Development using the relationship between the 10 specific service strategies and the three items which need to be enhanced services and determine the key strategies for improvement. The determination of the critical strategies is dependent on the total weight (TWi) in the Quality Function Development. We measure TWi as the sum of the values derived from multiplying each specific service strategy, which corresponds to the weight wi of each defective service item and the improvement index (δi): n TW i = i w i (4) Where, wi represents the weight of each specific service strategy corresponding to the three defective services; and δi represents the improvement index for the defective service. Based on the total weight, specific service strategies with high positive values are those that need increased resources to enhance customer satisfaction. Specific service strategies with higher negative values can have their resources reduced without loss of customer satisfaction. We determined the critical strategies which require more resources to be (D) Staff maintenance capability; (F) Professional knowledge of various car systems; and (G) Professional attitude of staff. The critical strategies for overloaded resources are (I) Customer Feedback and (J) Company message conveyed (Table 2). i 1 414

7 Table 2. Critical strategies found by quality function deployment for service quality improvement Weight (W i ) very strong 4.0 strong 3.0 normal 2.0 weak 1.0 Not relevant parts should be repaired instead of replacement of the whole set 17. regularevents held by the company 20. maintenance or repair should be transparent Defective Service Items Improvement index (δ i) (A)Buy advanced testing devices for different systems of (B) Make standards for repair or replacement of car parts (C) Make SOP for the cars repair 6. Using TRIZ Method to improve service quality Specific service strategies After determining critical service strategies, we use the TRIZ method for inventive problem solving to improve service quality in order to ensure the effectiveness of maintenance and repair at Jung-xian Auto Repair. TRIZ is the abbreviation of the Russian term for the Theory of Inventive Problem Solving. It is a systematic inventive technology developed by Russian researcher Genrich Altshuller [1] and his team after analyzing the characteristics of over two hundred thousand patents and classifying their inventive categories in the mid 1940s. The theory of inventive problem solving posits that when someone is looking for a solution to engineering problems, they frequently encounter contradictions in the system, and efforts to improve one feature of a system frequently result in defects in another part of the system. In fact, invention is a series of solving problems involving contradictions. Contradictions can be divided into two groups, technical contradictions and physical contradictions. Technical contradictions occur when improvement in one part of the system leads to reduced performance in another part of the system. For example, if the brightness of a light bulb is increased, its power demand also increases. Physical contradictions occur when two physical characteristics are in conflict, as when increasing the size of the wing to gain lift results in increased air resistance. When facing a problem which needs to be solved using contradiction theory, we first need to define whether it is technical or physical. If it is technical, it may be solved using the contradiction matrix. First, we determine the origin of the system contradiction based on 39 system features. We then list the parameters which need to be improved, along with the parameters of undesired results. The contradiction matrix is then constructed and solved using one of the 40 inventive tactics. The process of solving problems is shown in Figure 4[6]. If the problem is a physical contradiction, the first step is to examine the temporal, spacial, conditional, and structural separations. After the principle of separation is defined, 40 inventive tactics are used to solve the problem. (D) Staff maintenance capability (E)Work according to the procedures of work orders (F)Professional knowledge of various car systems Total Weight (TW i ) Critical Strategy Service (G) Professional attitude of staff (H) Little gifts for festivals (I) Customer Feedback (J) Company message conveyed

8 Figure 4. The TRIZ algorithm for creative problem solving Because the critical service strategies found in this study are technical contradictions, the contradictive problems are solved according to the process shown in Figure 4. This study constructed a mechanism to improve service quality against the critical service strategies as shown in Table 3. The 5 critical service strategies to be improved in Table 3 were divided into two categories: the three with the highest positive TW i in Table 2, indicating critical service strategies lacking resources, which are (D) Staff maintenance capability, (F) Professional knowledge of various car systems, and (G) Professional attitude of staff, and the two with the highest negative TW i, indicating the critical service issue of resource overload, which are (I) Customer Feedback, and (J) Company message conveyed. Category Resources lacking Critical service strategy (D)Staff maintenance capability (F) Professional knowledge of car systems TRIZ inventive principle Table 3. Improving the critical service strategies by TRIZ Illustration Segmentation Extraction Periodic Action Rushing Through Disposal Segmentation Prior Action Transition Into a New Dimension Periodic Effects Homogeneity Composite Materials Improve service quality Build evaluation standard for maintenance staff Maintenance staff need to know the functions of all parts and car systems which are prone to failure and safety issues Train the maintenance staff of all systems of the car Maintenance staff need to give advice for driving safety according to their experience with the current status of the customers' car Fire the maintenance staff who cannot meet the standard Train the maintenance staff professionally Recruiting individuals who have car maintenance learning experience Promote talented and experienced maintenance staff Maintenance staff obtain evaluation at regular intervals Maintenance staff should obtain certificates for different vehicles from the original maker Maintenance staff needs professional training on different car systems in addition to their own specialties. Stable Parameters Improvable Parameters

9 Overload Resources (G) Professional attitude of staffs required (I) Customer Feedback (J) Company message conveyed Segmentation Nesting Cushioning Do It In Reverse Rejecting and Regenerating Parts Transformati on of Properties Do It In Reverse Dynamics Feedback Mediator Local quality Rejecting and Regenerating Parts Dynamics Disposal Maintenance staff are assigned work based on their specialty Maintenance staff receive performance rewards at regular intervals Teach maintenance staff about repair ethics and job ethics Maintenance staff receive evaluations at regular intervals Fire the maintenance staff who are not competent. Discuss and share experiences via quality control cycles to build a valuable team Managers wander around randomly interacting with customers to increase customer recognition. Build quick feedback. Handle the problems on time to increase the confidence of the customers. Customer feedback channels should be flowing into the company. Ask a professional market research company to investigate the customer satisfaction to reduce costs. Cancel paper ad mailings, send via instead Pre-estimate the cycle period for car maintenance and inform customers in advance Upload information about the company that is subject to change on the website Build interactive e-communication for car information on social network sites like Facebook The TRIZ inventive technical contradictions problem solving progress to improve the critical service strategy (D) is shown in Table 3. (1) Since maintenance staff needs to have the capability to find and solve problems, it is necessary to improve staff capabilities without increases in the costs to the car repair company. Thus, the traits of the causes of system technical contradictions may be found in the 39 engine parameters. (2) The improvable parameter is the 31 st, object caused harm (car failure), while the stable parameters are the 36 th, device complexity, and the 37 th, difficulty of detection (adding extra devices). (3) Form the key factors of the contradiction matrix as shown in Table 4. (4) In the contradiction matrix in Table 4, the acceptable inventive features are 1, 2, 19, 21, 27 and 31. (5) According to 5 out of 6 inventive principles of 19, 1, 2, 21, and 27, approaches to improving service quality may be found. The 31 st inventive principle is not used for the reasons given below. (a) Principle 19, Periodic Action, defined as changing the way to obtain the requested results. According to the inventive principles, it may be improved by "Train the maintenance staff on all car systems". (b) Principle 1, Segmentation, is defined as dividing the system into segments virtually or in reality to isolate or integrate harmful or useful features of the system. According to the inventive principles, the way to improve is to "Build evaluation standards for maintenance staff". (c) Principle 31, Porous materials, is defined as changing the conditions of gases, liquids, or solids to make them have holes. This principle has no effect on the critical service strategy (D), so we ignore it. (d) Principle 2, Extraction, is defined as extracting harmful or useful parts or features either virtually or in reality. According to the inventive principles, the way to improve is "Maintenance staff need to know the functions of all parts and set in the car systems which are easy to be dangerous and fail to work". (e) Principle 2, Rushing Through, is defined as if something easily goes wrong at a certain speed, then increase the speed. According to the inventive principles, the way to improve is to "Maintenance staff needs to give advice for driving safety according to their experience with the current status of the 417

10 customers' car". (f) Principle 27, Disposal, is defined as using cheaper, simpler, or easier to handle objects to reduce the cost, increase the convenience, and extend operational life. According to the inventive principles, the way to improve is to "Fire the maintenance staff who cannot meet the standard". Table 4. Key factors of contradiction matrix Stable parameters Device complexity Difficulty in detecting Improvable parameters Object-generated harmful Conclusion Studies of car maintenance and repair commonly use one dimension to investigate consumer satisfaction. This study examines the two dimensions of service quality importance and service quality satisfaction with a performance matrix. We construct a questionnaire of 20 service items according to the services offered by the maintenance staff. Three services were found to be needing improvement after the service quality importance and satisfaction investigation. These included service item 9, parts should be repaired instead of replacement of the whole set, which fell in the zone of lacking resources, along with service item 20 of maintenance or repair transparency required. Service item 17 of regular events held by company fell into the zone of overloaded resource. This study used a Cause & Effect Diagram to analyze the three abnormal service items and listed 10 concrete service strategies. A Quality Function Deployment Table was then applied to define 5 key service strategies for improvement. The TRIZ innovation method was then used to construct a quality system that would improve maintenance and repair services at the auto repair company. 8. Acknowledgments The authors would like to express their appreciation to the National Science Council under Grant NSC E for the support of this research. 9. References [1] Altshuller. G., And Suddenly the Inventor Appeared TRIZ, the Theory of Inventive Problem Solving, Natalie Dronova Uri Urmanchev, [2] DeVellis, R. F., Scale Development Theory and Applications, London: SAGE, [3] Gay, L. R., Educational Research Competencies for Analysis and Application, New York: Macmillan, [4] Hung, Y. H., Huang, M. L., and Chen, K. S., Service Quality Evaluation By Service Quality Performance Matrix, Total Quality Management, Vol. 14, No. 1, pp.79-89, [5] Hsia, T. C., Chen, S. C., and Chen, K. S., "Enhancement of Service Quality in Internet-Marketing through Application of the Six Sigma Process", Journal of the Chinese Institute of Industrial Engineers, Vol. 26, No. 1, 11-21, [6] Hsia, T. C., Huang, S. C. and Chen, H. T., "Enhancing the Writing Quality of Aircraft Maintenance Technical Orders and Establishing a Management Mechanism for Maintenance Technicians using the Six Sigma Process," In David E. Malach (eds), Advances in Mechanical Engineering Research. Vol. 3, Nova Science Publishers, Inc., [7] Lambert, D. M. and Sharma, A., A Customer-Based Competitive Analysis for Logistics Decisions, International Journal of Physical Distribution and Logistics Management, Vol. 20, No. 1, pp. 23, [8] Yuxun Liu, "Decision-Making Model for Multidimensional Analysis of Preference Based on Intuitionistic Trapezium Fuzzy Set", JCIT, Vol. 8, No. 1, pp. 169 ~ 175, [9] Parasuraman, A., Zeithaml, V. A. and Berry, L. L., A Conceptual Model of Service Quality and Its Implications for Future Research, Journal of Marketing, Vol. 49, pp ,

11 [10] Parasuraman, A., Zeithaml, V. A. and Berry, L. L., Understanding customer expectation of service, Sloan Management Review, pp ,1991. [11] Yuehua Cai, Wujun Zeng, Wei yue Xiao, "Research and Application of Non-equidistant New Information GM (1,1) Model with Improved Initial Value", JCIT, Vol. 8, No. 1, pp. 182 ~ 188,