• Proceedings of the KIEE Conference
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• 2005.11b
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• pp.249-251
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• 2005

전력 산업구조개편으로 인하여 전력회사의 민영화가 진행됨에 따라 전력회사에서는 한정된 예산으로 배전계통을 운영함으로써 유지보수를 위한 충분한 여유가 없어지게 될 것이다. 이러한 환경에서 한정된 비용으로 계통의 신뢰도를 일정 수준 이상으로 유지해야만 하는 문제에 직면하게 되며, 이는 매우 어려운 일이다. 이를 위해서는 최소의 비용으로 최대의 유지보수 효과를 낼 수 있는 방법을 개발해야 하며, 최적의 유지보수 주기를 찾는 것이 중요한 문제라 할 수 있다. 본 논문에서는 이런 문제론 해결하기 위해, 유지보수 기기 선정 및 유지보수 주기를 결정하는데 있어 검증된 기법인 Reliability Centered Maintenance (RCM) 기법을 이용하였다. 배전계통 기기의 유지보수에 있어서 Four-state Markov 모델을 이용하여 기기의 유지보수에 드는 비용과 기기의 고장에 의한 정전비용 사이의 trade-off를 고려하여 총 비용이 최소가 되는 최적의 유지보수 주기를 찾고자 한다. 이를 위하여 기존의 모델에서 평균고장률(mean failure rate)을 사용한 것과는 달리 시변 고장률(time-varying failure rate)을 적용하였으며, 또한 유지보수에 따른 고장률의 감소도 고려함으로써 최적의 유지보수 주기를 결정할 수 있었다.

• Proceedings of the KAIS Fall Conference
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• 2010.11a
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• pp.367-369
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• 2010

본 논문은 열차제어시스템 유지보수업무의 최적화를 위한 정량적 주기산출방법에 관한 것으로, 특히 전장품과 같이 유지보수업무로 주로 교체업무가 선택되는 경우, 운영비용을 최적화하기 위한 교체주기를 정량적으로 산출하기위한 방법을 제시하고, 장치의 고장분포 데이터를 통해, 철도신호장치의 교체주기를 할당한다. 제시한 방법은 유지보수장치의 운영이력을 분석하여, 장치의 고장데이터를 바탕으로 고장분포를 확률적으로 모델링한 뒤, 정확한 LCC데이터가 적용될 때 새롭게 도입되는 장비 및 시스템의 유지보수업무주기를 할당이 가능하고, 이를 통해여 시스템의 운영안전을 보장하면서, 운용비용을 최적화 할 수 있다.

• 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 KIEE Conference
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• 2006.11a
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• pp.126-128
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• 2006

현재 배전부분도 사업부체제로 진행됨에 따라 구역 및 지역별로 배전계통을 운영하는 경쟁체제에 돌입하게 되었다. 또한 각 사업부별로 예산을 추진하여 배전계통을 운영하게 되며 배분된 예산으로 배전계통의 신뢰도 및 경제적 운영을 일정 수준으로 유지하여 타 사업부와 사업성을 경쟁해야 한다. 특히, 각 배전 사업부별로 경쟁해야 하므로 최소의 비용으로 최대의 유지보수 효과를 얻을 수 있는 방법을 개발해야 하며, 비용을 최소로 하여 최적의 점검 주기를 찾는 문제는 중요하다고 할 수 있다. 본 논문에서는 최적 유지보수 기기 선정과 최적 유지보수 주기를 결정하는데 있어서 적합한 기법인 배전 계통 유지보수 기법(Reliability Centered Maintenance, RCM)을 이용하였다. 이의 구현을 위하여 Markov chain 기법을 배전 계통 기기의 유지보수 모델에 적합하도록 수정하여 유지보수에 필요한 비용과 기기의 고장으로 인하여 발생할 수 있는 정전비용 등을 고려하여 최적의 점검 주기를 결정하고자 한다. 제안된 RCM의 알고리즘은 Dynamic Programming을 이용하여 점검 및 유지보수에 필요한 기기를 결정하는 부분과 유지보수의 실행 여부를 결정하는 decision 부분으로 되어있다. 사례연구를 통하여 본 논문에서 제안된 알고리즘의 적용가능성을 살펴보았다.

• Journal of the Korean Society for Railway
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• v.11 no.3
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• pp.240-247
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• 2008

Recently, railway corporations have built maintenance information systems and collected failure and maintenance data. For example Seoul Metropolitan Rapid Transit Corporation (SMRT) built the Electric Motor Unit-Information System (EMU-IS) which is the first maintenance information system in Korea. It has been operated from August, 2000. This paper deals with a case study on determining maintenance interval through reliability analysis using EMU-IS fault data. Door system is considered for the case study in which reliability is evaluated for operating time and distance and the overhaul interval is determined.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.1
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• pp.58-65
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• 2008

Reliability-Centered Maintenance plan for maintenance schedule of generating unit is being assessed in this paper. Maintenance schedule is a key index that can be used to determine stability and cost. In this paper, stochastic FMECA is described for the life assessment by using probability distribution, and combustion-turbine generations in Korean power systems have been assessed for maintenance schedule. Such an assessment can be a useful guide for maintenance plans in restructured power industry.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.198-205
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• 2009

It is known that the operation and maintenance cost is generally higher than the acquisition cost of rolling stocks. It is very important for reducing the operation and maintenance cost to acquire the rolling stocks which are well designed with regard to the operation and maintenance cost. Therefore life cycle cost including the operation and maintenance cost is needed to be considered from the acquisition phase. This article presents a procedure and a model for life cycle cost which are applicable to the acquisition of rolling stocks.

• Journal of the Earthquake Engineering Society of Korea
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• v.6 no.5
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• pp.29-36
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• 2002

In the maintenance and retrofit planning of a bridge system, the optimal strategy for inspection and repair are suggested by minimizing the expected total life-cycle cost, which includes the initial cost, the costs of inspection, repair, and failure. Degradation of seismic performance is modeled by using a damage function. And failure probability is computed according to the degree of damage detection by random vibration theory and the event tree analysis. As an example to illustrate the proposed approach, a 10-span continuous bridge structure is used. The numerical results show that the optimum number of the inspection and the repair are increased, as the seismic intensity is increased and the soil condition of a site becomes more flexible.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.4
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• pp.19-25
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• 2016

Engineering structures including civil infrastructures require a life-cycle cost and benefit during their service lives. The service life of a structure can be extended through appropriate inspection and maintenance actions. In general, this service life extension requires more life-cycle cost and cumulative benefit. For this reason, structure managers need to make a rational decision regarding the service life management considering both the cost and benefit simultaneously. In this paper, the probabilistic decision tool to determine the optimal service life based on cost-benefit analysis is presented. This decision tool requires an estimation of the time-dependent effective cost-benefit under uncertainty to formulate the optimization problem. The effective cost-benefit is expressed by the difference between the cumulative benefit and life-cycle cost of a deteriorating structure over time. The objective of the optimization problem is maximizing the effective cost-benefit, and the associated solutions are the optimal service life and maintenance interventions. The decision tool presented in this paper can be applied to any deteriorating engineering structure.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.4
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• pp.37-47
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• 2024

This study proposes a track maintenance quantity estimation model that considers evolution of rail fatigue damage and ballast settlement based on actual maintenance data from the Gyeongbu high-speed railway, and revises the existing life cycle cost (LCC) model for railway track. Using this model, maintenance quantities and life cycle costs based on different track quality levels are evaluated and discussed. According to the results, it is confirmed that applying the track maintenance quantity estimation model that accounts for rail fatigue damage and ballast settlement allows us to reasonably estimate maintenance costs close to the actual data. The track quality coefficient significantly influences both rail and ballast maintenance quantities, with ballast maintenance having a greater impact than rail maintenance. Additionally, as train speed increases, both rail and ballast maintenance quantities rise. Moreover, a higher track quality coefficient leads to a steeper increase in maintenance quantities with increasing train speed. Consequently, LCC also exhibits a faster growth rate over time with higher track quality coefficients and faster train speeds, resulting from an increased proportion of maintenance costs.