• 대한안전경영과학회지
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• 제19권3호
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• pp.89-95
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• 2017

This paper presents another maintenance policy for a group of units under finite operating horizon. A group of identical units are subject to random failures. Group maintenances are performed to all units together at specified intervals, and the failed units during operation are remained idle until the next group maintenance set-up. Unlike the traditional assumption of infinite operating horizon, we adopt the assumption of the finite operating horizon which reflect the rapid industrial advance and short life cycle of modern times. The units are under operation until the end of the operating horizon. Further, the operation of units are extended to the first group maintenance time after the end of the horizon. The total cost under the proposed maintenance policy is derived. The optimal group maintenance interval and the expected number of group maintenances during the horizon are found. It is shown that the proposed policy is better than the classical group maintenance policy in terms of total cost over the operating horizon. Numerical examples are presented for illustrations.

• 한국신뢰성학회지:신뢰성응용연구
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• 제11권4호
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• pp.433-445
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• 2011

Duty cycle is determined as the ratio of operating time to total time. Duty cycle in reliability prediction is one of the significant factors to be considered. In duty cycle application, non-operating time failure rate has been easily ignored even though the failure rate in non-operating period has not been proved to be small enough. Ignorance of non-operating time failure rate can result in over-estimated system reliability calculation. Furthermore, utilization of duty cycle in reliability prediction has not been evaluated in its effectiveness. In order to address these problems, two reliability models, such as MIL-HDBK-217F and RIAC-HDBK-217Plus, were used to analyze non-operating time failure rate. This research has proved that applying duty cycle in 217F model is not reasonable by the quantitative comparison and analysis.

• 한국물환경학회지
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• 제28권2호
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• pp.202-212
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• 2012

Due to the deterioration of water supply network and the deficiency of raw water, the water utility of local governments have performed various projects to improve their revenue water ratio. However, it is very difficult to estimate the cost for maintaining the revenue water ratio at higher level after completing the project, because local governments have different conditions affecting the operating and maintenance cost of water supply network. The purpose of this study is to present a procedure to estimate the operating and maintenance cost required to maintain the target revenue water ratio of the water supply network. For this purpose, we estimated the cost used only for operation and maintenance of water supply network of 164 local governments with the aid of K-Mean Clustering Analysis and the data from 40 representative local governments. Then, the regression analysis was performed to find relationship between revenue water ratio and the operating and maintenance cost with two different data sets generated by two classification methods; the first method classifies the local governments by means of k-means clustering, and the other classifies the local governments according to the index standardized by the operating and maintenance cost per unit length of water mains per revenue water ratio. The results shows that the method based on the index standardized by the cost and revenue water ratio of each government produces more reliable results for finding regression equations between revenue water ratio and the operating and maintenance cost only for water supply network. The estimated regression equations for each group can be used to estimate the cost required to keep the target revenue water ratio of the local government.

• 한국신뢰성학회지:신뢰성응용연구
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• 제17권1호
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• pp.58-65
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• 2017

Different from general operating policies applied for various waiting line situations, two complementary dyadic operating policies are applied alternatingly to a single server maintenance service center model. That is, either of the two dyadic Min (N, T) or Max (N, T) policy is applied to operate such center first and the other operating policy should be applied later, and then the same sequence of both operating policies is followed repeatedly. This operating policy is denoted by the Minimax (N, T) policy. Purpose: Because of the newly introduced operating policy, important system characteristics of the considered service center model such as the expected busy and idle periods, the expected number of customers in the service center and so on should be derived to provide necessary information for determination of the optimal operating policy. Methods: Based on concepts of the newly introduced Minimax (N, T) policy, all necessary system characteristics should be redefined and then derived by constructing appropriate relations between complementary two dyadic operating policies. Results: Desired system characteristics are obtained successfully using simple procedures developed by utilizing peculiar structure of the Minimax (N, T) policy. Conclusion: Applying Minimax (N, T) operating policy is equivalent to applying the simple N and T operating policies alternatingly.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.1412-1417
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• 2011

Safety is soaring up as a core value in accordance with the recent improvement of operating speed & incidents. rolling stock is a kind of system which works together with several components. one component has an effect on the sub-system, which can cause to the train safety operation, therefore reliability management of the major components of rolling stock is a kind of solution to the safety operation of train, but realistically maintenance in korea performed based on period rather than TBO of major components, but Japan does new maintenance system based on the major components, which optimizes maintenance tasks. actually Japan can apply to new maintenance system because they are ready in planning step but in this study, making a reliability data of major components and review the adaptability of new maintenance system to the rolling stock operating in Ansan line.

• 산업경영시스템학회지
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• 제18권36호
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• pp.287-295
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• 1995

This paper is concerned with cost analysis model in periodic maintenance policy. Generally periodic maintenance policy in which item is repaired periodic interval times. And in the article minimal repair is considered. Mimimal repair means that if a unit fails, unit is instantaneously restored to same hazard rate curve as before failure. In the paper periodic maintenance policy with minimal repair is as follows; Operating unit is periodically replaced in periodic maintenance time, if a failure occurs between minimal repair and periodic maintenance time, unit is replaced by a new item until tile periodic maintenance time comes. Also unit undergoes minimal repair at failures in minimal-repair-for-failure interval. Then total expected cost per unit time is calculated according to scale parameter of failure distribution. Maintenance cost factors are included operating, fixed, minimal repair, periodic maintenance and new item replacement cost. Numerical example is shown in which failure time of system has weibull distribution.

• 한국산학기술학회논문지
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• 제21권9호
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• pp.82-91
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• 2020

최근 무기체계 연구개발은 획득비 중심의 종합군수지원 개념을 적용하던 시기에서 운용유지비를 포함한 총수명 주기관리 개념으로 확장 적용하고 있다. 운용유지비의 항목 및 산출식은 규정 등을 통해 정의하고 있지만, 이는 공학적 추정을 기초로 하여 실제 무기체계의 설계, 운용/정비 절차 특성을 깊이 있게 고려하지 못하고 있다. 그래서 본 연구는 이러한 부분을 보완하고 보다 정확한 운용유지비 산출을 위한 시뮬레이션 설계 방법을 제시한다. 연구 절차로는 다음과 같다. 먼저 운용유지비 항목 및 산출식을 시뮬레이션 결과를 적용 가능하도록 정의한다. 그리고 시뮬레이션 결과가 보다 현실성을 정확히 반영 가능하도록 시뮬레이션 설계 고려사항을 검토하여 개발한다. 이때 고려 사항은 무기체계 부품 목록, 운용 일정, 운용/정비/보급 시설 별 제원 정보 및 기초 비용 정보(인건비, 수리부속 / 지원 장비 구매 단가 등) 등이 있다. 이러한 연구는 기존 보다 쉽고, 정확한 운용유지비 산출에 효과가 있음을 기대한다.

• 산업경영시스템학회지
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• 제18권34호
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• pp.139-146
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• 1995

This study is concerned with cost analysis in periodic maintenance policy. Generally periodic maintenance policy in which item is repaired periodic interval times. And in the article minimal repair is considered. Minimal repair means that if a unit fails, unit is instantaneously restored to same hazard rate curve as before failure. In the paper periodic maintenance policy with minimal repair is as follows; Operating unit is periodically replaced in periodic maintenance time, if a failure occurs between minimal repair and periodic maintenance time, unit is replaced by a spate until the periodic time comes. Also unit undergoes minimal repair at failures in minimal-repair-for-failure interval. Then total expected cost per unit time is calculated according to maintenance period and scale parameter of failure distribution. Total cost factors ate included operating, fixed, minimal repair, periodic maintenance and replacement cost Numerical example is shown in which failure time of system has erlang distribution.

• 한국건설관리학회논문집
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• 제7권6호
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• pp.185-192
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• 2006

공공임대주택의 경과연수가 증가함에 따라 시설물의 노후화로 인한 유지관리비용이 급격히 증가하고 있다. 이에 효과적으로 대처하기 위해서는 우선 비용에 대한 정확한 예측을 하고 필요한 재원을 확보하는 일이 무엇보다도 중요하다 따라서 시설물 유지관리비에 영향을 미치는 요인들을 분석하고, 이를 고려한 비용 예측방법의 개발이 필요하다. 공공임대주택 운영관리비의 약 60%를 국가에서 지원하고 있는 미국의 경우는 수년간의 실적데이터를 바탕으로 운영관리비를 효과적으로 예측할 수 있는 방법을 개발하여, 공공임대주택이 적정한 수준에서 잘 운영될 수 있도록 하고 있다. 그러나 아직까지 국내에서는 공공임대주택을 대상으로 운영관리비 영향요인이나 예측 툴에 관한 연구 실적은 매우 미흡한 실정이다. 본 논문은 최근 5년간 공공임대주택에 실제 지출된 운영관리비를 바탕으로, 시설물 유지관리비용에 미치는 영향요인과 요인별 영향력 등을 밝혀냄으로써, 향후 객관적이고 정확한 비용예측 도구를 개발하는데 일조 하고자 한다.

• 산업공학
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• 제23권3호
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• pp.221-228
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• 2010

With the development of science and technology, modern submarines are equipped with high technology devices and multi-functioned precise armaments, consequently, acquisition cost as well as maintenance cost of the submarines are getting higher and higher. However, tight defense budget forces navy to significantly reduce military operating and maintenance costs. In this study, the maintenance and operating costs of submarine Jangbogo-II are estimated through M&S (Modeling and simulation) methodologies in order to reasonably and consistently work out the requirement verification system of Jangbogo-II. The maintenance and operating costs of Jangbogo-II along the next 25 years are estimated as 312.65 billion won via engineering analysis methods while 312.69 billion won from PRICE Model, which shows only 0.04 billion won differences as a whole. This study is expected to be able to provide meaningful decision making data for not only short and/or mid term operating planning but military budgeting.