• Journal of Korean Institute of Industrial Engineers
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• v.19 no.3
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• pp.81-90
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• 1993

This article concerns the problem of determining the optimal spare inventory level for multiechelon repairable-item inventory system. The system we are concerned has several bases and a central depot. When an item fails, it is dispatched to a repair facility and, a spare, if available, is plugged in immediately. When the failed item is repaired, it is sent to the base and either used to fill a backorder or stored at a spare inventory point. We develop an optimal algorithm to find the spare inventory level at each base spareswhich minimizes the total expected cost and, simultaneously, satisfies a specified minimum service rate. The algorithm is applied to examples with good results.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.57-64
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• 2007

RIMS（Rolling Stock Information Maintenance System)　was installed in structure which it can analyze the data base in need of credibility maintenance. So it could accumulate real data without repulsion of working spot. Information system was installed not following to system but following to working spot. The development of RIMS project was started from March 29, 2001 and it has been operating from October 12, 2004 in Chang-dong Car depot for light maintenance in charge subway line4. So substantial data base was accumulated for three years. This study calculated all RAMS data by analyzing data base accumulated in RIMS and used in dada base about credibility maintenance and found investigation of propriety, expectation of the life cycle cost, the improvement plan on credibility of sorts of cars and formation about the cycle of repairing and maintenance. This got MKBSF MKBF and MTBF about devices and sorts of line4 Rolling Stocks for it.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.143-150
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• 2007

RIMS（Rolling Stock Information Maintenance System)　was installed in structure which it can analyze the data base in need of credibility maintenance. So it could accumulate real data without repulsion of working spot. Information system was installed not following to system but following to working spot. The development of RIMS project was started from March 29, 2001 and it has been operating from October 12, 2004 in Chang-dong Car depot for light maintenance in charge subway line4. So substantial data base was accumulated for three years. This study calculated all RAMS data by analyzing data base accumulated in RIMS and used in dada base about credibility maintenance and found investigation of propriety, expectation of the life cycle cost, the improvement plan on credibility of sorts of cars and formation about the cycle of repairing and maintenance. This got MKBSF MKBF and MTBF about devices and sorts of line4 Rolling Stocks for it.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.13 no.22
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• pp.17-24
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• 1990

The inventory problem of the repairable items is modeled as a queueing network for the purpose of determining the number of spares in a multi-echelon repair system subject to stochastic failure. In this paper, we are considering a finite number of repairman at each base and the depot. After repair job has completed, the repaired items are returned to the base where they have originated. For the system, we identify the distribution of the total number of failed items which belongs to a base and develope a method to find spare inventory levels of the repairable items at each base to satisfy a specified minimum fill rate.

• Journal of the military operations research society of Korea
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• v.24 no.2
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• pp.146-161
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• 1998

This article develops model of the nonstationary state behavior of the multiechelon spare parts provisioning systems. This study is concerned with a problem of determining the near optimal requirements level of the spare parts, especially Concurrent Spare Parts(CSP). CSP is supplied with the procurement of new equipment system, and is used to sustain the equipment without resupply during the initial coverage period. We consider this situation as a multiechelon inventory model with several bases and one depot. And we assume an equipment system which consists of many types of parts would grounded if one of the parts fail. Also this multiechelon CSP problem is considering the nonstationary poisson failure process and nonstationary exponential repair process in a dynamic environment. We develop an efficient computational procedure to find the near optimal number of spare parts minimizing the total expected cost, while achieving the required system availability. Finally we present a simple example of suggested method.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.1268-1275
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• 2005

The computerization works and environment have been changed from simple transaction and data process request to system connection request, from data computerization to application work automation and process computerization through IT development and Internet spread. Recently, BPM(Business Process Management) concept has been widely propagated. It is expanding interest of business subject. Korea Railroad is operating train operation management system through 5 regional headquarters and organizations under the influence of each regional headquarter. But integrated operation and management of communication each department, work flow management and resources of depot equipment and materials have to need a lot of effort and time in huge organization as Korea Railroad. Therefore, this article realized Web Based BPM Group Ware. This article will define Korea Railroad organization and business process in using this Group Ware. And it will introduce Korea Railroad computer manage system of this Group Ware and efficient Korea Railroad Business Process through modeling and operating department work and resources management in Korea Railroad.

• Journal of the military operations research society of Korea
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• v.16 no.2
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• pp.96-104
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• 1990

This paper concerns the problem of deciding the rational spare inventory levels for efficient use of a limited defence budget and, at the same time, for enhancing the operation rate of equipement/weapons in the army. The system we are concerned has a finite number of repairmen at each base and the depot. After repair job has completed, the repaired items are returned to the base where they have originated. For the system, we identify the distribution of the total number of failed items which belong to a base and develope a method to find spare inventory levels of repairable items at each base to satisfy a specified minimum fill rate.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.76-82
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• 2019

This study has done to search for a solution to remove risk limitedly caused by separating weapon system acquisition from operation and maintenance at the view point of Logistic Commander who's responsible for stable operation and maintenance after acquiring weapon system. At the System development stage, unverified overhaul development plan may cause additional manpower and costs after the development, and furthermore it is likely to have risk to lower reliability of the military. Thus, research and development agency should write overhaul development plan at the System development stage, and it should be verified through evaluation and verification test. Secondly, during research and development, institutional supplementation is needed to calculate human and material resources writing overhaul development plan. Thirdly, it should be able to analyze proper operation & maintenance plan and cost for overhaul plan at the pre-investigation stage. Fourthly, the base which can develop overhaul concept and overhaul factors should be included in the need and need determination document. Lastly, for the weapon system which has small amount of high power figure, project management should be performed to be able to specify at the each acquisition level of weapon system to realize Article 28, clause 3 and 4 of Defense business law.

• Journal of Intelligence and Information Systems
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• v.13 no.1
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• pp.49-58
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• 2007

MDPDPTW (Multi-Depot Pickup and Delivery Problem with Time Windows) is a typical model among the optimization models based on the pickup and delivery flow in supply chains. It is based on multi-vehicles in multi-depots and does not consider moving vehicles near pickup and delivery locations. In ubiquitous environments, it is possible to obtain information on moving vehicles and their baggage. Providing the proper context from the perspective of moving vehicles and their baggage allows for more effective vehicle routings. This study proposes Integer Programming-based MDPDPTW including the information on moving vehicles and their baggage in a ubiquitous environment: u-MDPDPTW, and shows the viability and effectiveness of u-MDPDPTW through comparative experiments of MDPDPTW and u-MDPDPTW.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.44 no.3
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• pp.39-49
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• 2021

The Korean Air-Force aircraft maintenance depot paints the exterior of various aircraft, including high-tech fighters. Aircraft exterior painting is a maintenance process for long-term life management by preventing damage to the aircraft surface due to corrosion. The de-painting process is essential to ensure the quality of aircraft exterior paints. However, because the Korean Air-Force's de-painting process is currently done with sanding or Plastic Media Blasting (PMB) method, it is exposed to harmful dust and harmful compounds and consumes a lot of manpower. This study compares the de-painting process currently applied by the ROK Air-Force and the more improved process of the US Air Force, and performs economic analysis for the introduction of advanced equipment. It aims to provide information that can determine the optimal time to introduce new facilities through Cost-Volume-Profit (CVP) analysis. As a result of the analysis, it was confirmed that the sanding method had the most economical efficiency up to 2 units per year, the PMB method from 3 to 21 units, and the laser method from 22 units or more. In addition, in a situation where the amount of de-painting work is expected to increase significantly due to the increase in fighters in future, BEP analysis was conducted on the expansion of the existing PMB method and the introduction of a new laser method. As a result of the analysis, it was confirmed that it is more economical to introduce the laser method when the amount of work exceeds the PMB work capacity(18 units per year). The paper would helpful to improve the productivity and quality of the Korean Air Force Aircraft maintenance depot through timely changes of facilities in the workplace in preparation for expansion.