• The Journal of Information Systems
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• v.31 no.3
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• pp.197-220
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• 2022

Purpose The purpose of this study is to identifies the demand pattern categorization of repair parts of Automotive After-sales Service(A/S) and proposes a demand prediction model for Auto repair parts using Long Short-Term Memory (LSTM) of artificial neural networks (ANN). The optimal parts inventory quantity prediction model is implemented by applying daily, weekly, and monthly the parts demand data to the LSTM model for the Lumpy demand which is irregularly in a specific period among repair parts of the Automotive A/S service. Design/methodology/approach This study classified the four demand pattern categorization with 2 years demand time-series data of repair parts according to the Average demand interval(ADI) and coefficient of variation (CV²) of demand size. Of the 16,295 parts in the A/S service shop studied, 96.5% had a Lumpy demand pattern that large quantities occurred at a specific period. lumpy demand pattern's repair parts in the last three years is predicted by applying them to the LSTM for daily, weekly, and monthly time-series data. as the model prediction performance evaluation index, MAPE, RMSE, and RMSLE that can measure the error between the predicted value and the actual value were used. Findings As a result of this study, Daily time-series data were excellently predicted as indicators with the lowest MAPE, RMSE, and RMSLE values, followed by Weekly and Monthly time-series data. This is due to the decrease in training data for Weekly and Monthly. even if the demand period is extended to get the training data, the prediction performance is still low due to the discontinuation of current vehicle models and the use of alternative parts that they are contributed to no more demand. Therefore, sufficient training data is important, but the selection of the prediction demand period is also a critical factor.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.44 no.2
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• pp.24-35
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• 2021

Due to increasing awareness on the treatment of end-of-use/life products, disassembly has been a fast-growing research area of interest for many researchers over recent decades. This paper introduces a novel lot-sizing problem that has not been studied in the literature, which is the service-parts lot-sizing with disassembly option. The disassembly option implies that the demands of service parts can be fulfilled by newly manufactured parts, but also by disassembled parts. The disassembled parts are the ones recovered after the disassembly of end-of-use/life products. The objective of the considered problem is to maximize the total profit, i.e., the revenue of selling the service parts minus the total cost of the fixed setup, production, disassembly, inventory holding, and disposal over a planning horizon. This paper proves that the single-period version of the considered problem is NP-hard and suggests a heuristic by combining a simulated annealing algorithm and a linear-programming relaxation. Computational experiment results show that the heuristic generates near-optimal solutions within reasonable computation time, which implies that the heuristic is a viable optimization tool for the service parts inventory management. In addition, sensitivity analyses indicate that deciding an appropriate price of disassembled parts and an appropriate collection amount of EOLs are very important for sustainable service parts systems.

• Journal of Biosystems Engineering
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• v.9 no.1
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• pp.5-10
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• 1984

Using the renewal theory based on the Weibull distribution, an estimation was made on the number of replacement parts annually required for the after-service of some major parts of power tiller at the local repair shops or dealers. The production requirements of the parts were also estimated for the service in the next 5 years following the sales of power tillers.

• Journal of the Korean Society of Clothing and Textiles
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• v.35 no.11
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• pp.1271-1284
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• 2011

This study improves the fitness of Air Force winter service uniforms through the development of a shirt pattern drafting method and automatic pattern drafting program for MTM production. A calculation formula is formed through a correlation analysis and regression analysis using Size Korea 2004 3D measurement data after analyzing 4 kinds of existing shirt pattern drafting methods and 3 types of shirt patterns currently used for the Air Force service uniform. The results of this study are as follows: The developed pattern drafting method has 4 parts that use calculated dimensions: neck base width, front interscye, back interscye and scye depth. Other body measuring parts that have a high correlation with calculation parts are inserted into regression analysis as independent variables to create dimension calculation formulas. The result of the final study patterns were better than existing winter service uniforms in nearly all items for the appearance evaluation and motion adaptability evaluations. The method was converted into an automatic pattern drafting program using C++ after the completion of pattern drafting method development.

• Journal of Korean Society for Quality Management
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• v.33 no.4
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• pp.12-20
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• 2005

Supply chain management is a total systems approach to delivering manufactured products to the end customer. Using information technology to coordinate all elements of the supply chain from parts suppliers to retailers achieves a level of integration that is a competitive advantage not available in traditional logistics systems. On the other hand, service chain management is an analogous systems approach that is especially suitable for delivering mobile services such as parcel delivery, cable installation, and home health care. The key elements that distinguish service supply chain management from supply chain management are bidirectional optimization, management of productive capacity, and management of perishability. The purpose of this study is to maintain the construction of service chain management by proving that service quality in after-sales service can be improved through service chain management. First of all, supply chain management, service quality, and service chain management were introduced in theoretical research. In empirical research, it was selected the domestic enterprise that produce electronic appliances with after-sales service, and some customers using the enterprise's after-sales service in the metropolitan area were selected as a sample by convenience sampling method and examined.

• Journal of Biosystems Engineering
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• v.28 no.6
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• pp.537-544
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• 2003

The objectives of this study were to investigate the failure characteristics of a total of 90 parts of tractor driveline, and to predict their average annual demands required to perform the after-sales service. The failure characteristics such as failure mode, mean time between failures, characteristic life and reliability were analyzed using the data collected through the experienced mechanics at the part centers of the tractor manufacturers. The analysis was based on the assumption that the failure distribution follows the Weibull distribution. The average annual demands were also predicted for the replacement parts using the mean time between failures and the renewal theory based on the Weibull distribution. The results of the study revealed that the driveline parts failure was mostly from wearout and their average characteristic life is about 1.760 hours. The estimated mean time between failures was in a range of 670∼3,740 hours and reliability in a range of 40∼60％. The annual replacement demands were in a range of 4∼45 for a service of 100 tractors.

• Culinary science and hospitality research
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• v.11 no.4 s.27
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• pp.198-213
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• 2005

This study was administered to demonstrate how unsatisfied customers would be influenced by the change in the quality of the service delivered to them after the dissatisfaction occurs. In light of the above, the objective of this study is to find out what leads to dissatisfaction in the minds of the consumers and also to identify the common behavioral patterns indicated by unsatisfied consumers. This study consists of two parts: a research based on the review of the literature and empirical study methods. As a result, a research for the popular forms of complaining patterns shows opportunities for restaurants to come up with measures to improve their service quality when customers are unsatisfied. In service recovery situation, distributive and interactional justice significantly influence customers' repurchase. Therefore, firms ought to offer monetary compensation, explain about the problems, and make their best efforts to recover the failure because the efforts also affect repurchase.

• Proceedings of the Korean Reliability Society Conference
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• 2001.06a
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• pp.235-238
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• 2001

It is well known that the reliability of materials of mechanical products is becoming more and more important not only for assurance of quality, but for international competition of products. In order to assure the reliability of materials or mechanical products nondestructive evaluation (NDE) techniques are playing more important roles. The existence of Internal defects in materials or mechanical parts is served as crack initiation site during the various loading condition. Historically, nondestructive evaluation (NDE) technique has been used almost exclusively for detecting microscopic discontinuities In materials or mechanical parts after they have been in service to expand the role of the NDE to include all aspects of materials production and application. Research efforts are being directed at developing and perfecting NDE techniques capable of monitoring (1) materials production processes (2) material integrity following transport, storage and fabrication and (3) the amount and rate of degradation during service. In addition, efforts are underway to develop technique capable of quantitative discontinuity sizing, permitting determination of response using fracture mechanics analysis, as well as techniques for quantitative materials characterization to replace the qualitative techniques used in the past. In this paper, the important role of NDE technology for reliability assurance of materials/mechanical parts is introduced.

• International Commerce and Information Review
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• v.6 no.2
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• pp.107-127
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• 2004

The rapid development of internet information technology has increased interest in e-Trade these days, but it is not activated greatly up to now. In order to promote e-Trade, it is essential to construct cooperative process such as connecting systems among trade related parties. Building e-Trade platform which is based on the infrastructure of the past trade automatic system is key point of promoting e-Trade. To do this, a study on the basic concept and specific components of e-Trade platform is needed absolutely. At this point of view, after this paper has examined domestic and foreign studies on the fundamental technologies about electronic commerce, it drew several key technologies that could be applied to e-Trade considering the current IT trend. Then it evaluates these technologies according to Technology Reference Model(TRM) of the National Computerization Agency. This will help us to show the operation strategy as well as the concept of future e-Trade platform and its composition. On the basis of the theoretical background, this paper classified NCA's technology model into 6 fields, which are application. data, platform, communication, security and management. Considering the key technologies, e-Trade platform has to be mutually connected and accept international standards such as XML. In the aspect of business side, trade relative agencies' business process as well as trading company's process has to be considered. Therefore, e-Trade platform can be classified into 3 parts which are service, infrastructure and connection. Infrastructure part is compared of circulating and managing system of electronic document, interface and service framework. Connecting service (application service) and additional service (application service) consist of service part. Connecting part is a linking mutual parts and can be divided into B2B service and B20 service. The organization operating this e-trade platform must have few responsibilities and requirements. It needs to positively accept existing infrastructure of trade automatic system and improving the system to complete e-trade platform. It also have to continuously develop new services and possess ability to operate the system for providing proper services to demanders. As a result, private sector that can play a role as TTP(Third Trust Party) is adequate for operating the system. In this case, revising law is necessary to support the responsibility and requirement of private sector.

• Journal of the Korean Dietetic Association
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• v.7 no.1
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• pp.87-104
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• 2001

This study was conducted as a part of the project developing the standards of national board test for the dietitian's licence. The purpose of this study was to define the job description of dietitians, and to describe the task elements based on the detailed analysis of the dietitians' work. This study team established the research team which was composed of food and nutrition experts, 7 of registered dietitians and 3 of university professors. Draft job description form was made to fully explain the dietitians' task elements, process and sequence by the research team. Final job description form was confirmed after the validity of 576 task elements was reevaluated upon 4 point scale test based on the frequency, importance, and difficulty by 21 field registered dietitian by the study team. It was also confirmed by the university. This form was formated by following DACUM method which analyzed the job description containing duty, task and task elements. It was organized to include every dietitians' work and to describe the every detailed process of work. Duty was defined as the specific and independent work as a dietitian, and was composed of 17 parts, i.e 10 parts in food supply management area and 6 parts in nutritional care service area and self promotion area. Duties were also divided into 99 tasks containing the 576 detailed task elements to describe definite action, steps and decisions. Seventeen parts are following; menu planning, storage and inventory control, food production, meal service, waste management, sanitation, equipment and facility management, human resource management, financial management, nutrition assessment of life cycle, nutritional assessment of several disease, nutritional assessment in specific condition, medical nutrition therapy, nutritional education, public health nutrition and self promotion. If these protocols are properly performed and presented, they can provide the likelihood that dietetics professionals work as a primary contributors in promoting health care and preventing disease nationally.