• Journal of the Korean Society for Railway
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• v.14 no.3
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• pp.216-221
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• 2011

An important problem in reliability analysis for repairable systems is to model the maintenance effect. The most of researches have assumed two extreme cases; one is perfect maintenance and the other is minimal maintenance. However, many of maintenances performed by domestic subway operators are imperfect maintenances which have the effect between both of two extreme cases. This article deals with the problem determining the imperfect preventive maintenance intervals based on failure data in units of the PDS(passenger door system) in Metro EMU. This paper deals with a case study on determining imperfect maintenance interval by using the level of maintenance effect through reliability analysis of PDS.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1539-1544
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• 2008

There is a existing study dealing with the case that the effect of preventive maintenances to restore the door system is imperfect. When the effect of the preventive maintenance is imperfect, we need to consider the maintenance effect for making reliable and economical maintenance policies. The maintenance policies applicable for imperfect maintenance cases are considered and their effectiveness are evaluated through simulation in cases of passenger door system:PDS.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.1
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• pp.48-55
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• 2016

The assessment and prediction of service life of a structure are usually under uncertainty so that rational probabilistic concepts and methods have to be applied. Based on these rational assessment and prediction, optimum maintenance strategies to minimize the life-cycle cost and/or maximize the structural safety can be established. The service life assessment and prediction considering maintenance actions generally includes effects of maintenance types and times of the structural components on the service life extensions of structural system. Existing researches on the service life management have revealed the appropriate system modeling considering the correlation among the components is required for system reliability analysis and probabilistic service life estimation. However, the study on correlation among the maintenance actions is still required. This paper deals with such a study for more effective and efficient service life management. In this paper, both the preventive and essential maintenances are considered for the extended service life estimation and management.

• Journal of the KSME
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• v.34 no.11
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• pp.836-844
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• 1994

LNG 인수기지 건설에 있어 주요 기자재는 외국에서 구입하고 이들 설비의 설치 및 시운전은 제작사 기술진의 감리하에 이루어졌다. 그간 천연가스 사업의 계속적인 발전으로 가스설비의 국산화가 상당히 이루어졌고, 국내 건설기술의 향상으로 외국인 감리자의 수요가 많이 감소하 였으나 현재도 LNG 저장탱크의 건설감리는 외국인의 책임하에 수행되고 있다. LNG 설비의 운 전은 완전한 기술자립이 이루어졌으며, 설비의 점검\ulcorner보수 또한 우리 기술진이 수행하나, 핵심 부품의 고장이 발생한 경우는 제작사의 전문가가 보수를 시행하는 경우가 많다. 이에 대한 대 책으로서 설비의 운전\ulcorner유지\ulcorner보수 기술을 더욱 축적하여 설비의 안정적 운영을 확고히 하고, 설비의 안전을 향상시키는 기술개발을 계속 추구하여야 할 것이다.

• Proceedings of the Korean Information Science Society Conference
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• 2011.06a
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• pp.206-209
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• 2011

기존의 요구사항 추적테이블은 요구관리적 관점에서 요구사항의 일관성, 완전성 확보를 목표로 하거나 요구사항 누락과 충돌, 중복 방지 요구사항 변경관리 측면만을 강조해 왔다. 그러나 자체 솔루션 개발관점과 유지보수 측면에서 제시된 요구사항 추적테이블이 없었다. 따라서 본 논문에서는 Pain Chain을 근간으로 개발 후 유지보수 요청관리에 효과적인 요구사항 추적테이블 방안을 제시하고자 한다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.12
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• pp.8700-8706
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• 2015

The first driving device of the power bogies for the Korean high-speed railway vehicle consists of the traction motor (TM) and the motor reduction gears unit (MRU). Although TM and MRU are the mechanically integrated structures, their time between overhauls (TBO) have two separate intervals due to different technical requirements(i.e. TBO of MRU: $1.8{\times}10^6km$, TBO of TM: $2.5{\times}10^6km$). Therefore, to reduce the unnecessary number of preventive maintenances, it is important to evaluate the optimal TBO with a viewpoint of reliability-center maintenance towards cost-effective solution. In this study, derived from the field data in maintenance, fault tree analysis and failure rate of the subsystem considering criticality of the components are evaluated respectively. To minimize the conventional total maintenance cost, the same optimal TBO of the components is derived from genetic algorithm considering target reliability and improvement factor. In this algorithm, a chromosome which comprised of each individual is the minimum preventive maintenance interval. The fitness function of the individual in generation is acquired through the formulation using an inverse number of the total maintenance cost. Whereas the lowest common multiple method produces only a four percent reduction compared to what the existing method did, the optimal TBO of them using genetic algorithm is $2.25{\times}10^6$km, which is reduced to about 14% comparing the conventional method.

• Journal of the Korean Society of Safety
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• v.12 no.3
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• pp.185-191
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• 1997

현재 우리나라에는 상당량의 천연가스 배관 및 송유관이 지하에 매설되어 있고 그 길이는 매년 큰 폭으로 증가하고 있다. 이러한 배관은 배관건설공사 및 공사후 유지, 보수 관리시 배관의 파괴와 관련된 여러가지 상황이 존재할 수 있다. 즉 외부에서 작용하는 다양한 요인이나 배관 내부요인에 의해 배관이 완전한 파단까지는 이르지 않더라도 손상을 받는 경우가 생긴다. 배관에 손상이 발생하였을 때 그 원인을 규명하고 처리방안을 마련하는 작업이 필요하다. 이러한 것들을 사전에 미리 예방하고 손상해석을 올바르게 하는데 필요한 것이 배관손상사례에 대한 데이터베이스이다.

• 시스템엔지니어링워크숍
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• s.1
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• pp.1-8
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• 2003

시스템 개발환경이 대형화, 복잡화됨에 따라 개발 생명주기의 각 단계에서 발생하는 요건은 기술적, 관리적 측면에서 많은 영향을 받게 되었다. 즉, 개발 생명주기의 초기단계에서 요건에 대한 잘못된 이해나 분석, 개발 영역에 대한 충분한 이해와 관리의 부재 및 계속적인 변경 요구는 부정확성하고 불완전한 요건을 발생시키고, 다른 요건과의 충돌 및 일관성 결여 등을 발생시킬 수 있다. 이러한 결과는 전체적인 시스템의 완전성과 성능 등에 커다란 영향을 주고 유지보수에 많은 비용과 노력을 요구한다. 본 연구에서는 이러한 문제점을 해결하기 위하여 실무 프로젝트 개발에 적용할 수 있도록 요건관리와 관련된 프로세스와 활동을 요구공학을 기반으로 완전성과 일치성을 가진 요구사항의 생성 및 관리 등을 포함하는 총체적인 활동과 원칙에 대한 공학적 접근을 제시하여 전체 소프트웨어 개발비용과 위험부담을 경감시키며 품질향상을 이룰 수 있도록 한다. 또한, 각 업무 도메인과 개발 환경에 따라 적절하게 적용할 수 있도록 프로세스와 활동을 커스터마이징 및 컴포넌트화하고 요구사항 관리 도구의 프로토타입을 제시한다.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1204-1212
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• 2008

This study enables to troubleshoot the problems of the existing dual system with the help of the implementation of totally dualized fault-tolerant system to L-CTC computer and HADAX, and equipments are simplified and systems are modernized with the addition of the control function, as a upgraded LCP control system, to L-CTC computer on the basis of WINDOWS based O/S switched from DOS environment. An error on Microlok, which is aninterlocking apparatus, forwarded to L-CTC computer ensures to handle the false data during the operation of the system. This paper discusses a sure way to prevent the deterioration of (SMRT) L-CYC system and to bolster its stability with formation of the dual system. Additionally, WINDOW based O/S consisting of L-CTC computer leads to simplification and modernization of facilities and enhances maintenance functions offering centralization for branch offices and machine rooms as well.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.2
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• pp.1-7
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• 2016

Although the second driving device of KTX, which consists of the wheel and the axle reduction gears unit, is a mechanically integrated structure, its preventive maintenance (PM) requires two separate intervals due to the different technical requirements. In particular, these subsystems perform attaching and detaching work simultaneously according to the maintenance directive. Therefore, to reduce the unnecessary amount of PM and high logistic availability of the train, it is important to optimize PM with regard to reliability-centered maintenance toward a cost-effective solution. In this study, fault tree analysis and reliability of the subsystems, considering the criticality of the components, were performed using the data derived from field data in maintenance. The cost optimization of the PM was derived from a genetic algorithm considering the target reliability and improvement factor. The cost optimization was derived from a maximum of the fitness function of the individual in generation. The optimal TBO of them using the genetic algorithm was 2.85x106 km, which is reduced to approximately 21% compared to the conventional method.