• 산업경영시스템학회지
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• 제20권44호
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• pp.263-271
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• 1997

This paper presents a preventive maintenance model for determining the preventive replacement period of a system in which a failure rate is affected by the cumulative damage of fault and inspection. Especially, the failure rate function is considered to be a function of the cumulative damage of the fault and inspection time. Types of replacement considered are preventive replacement and failure replacement. Failure rate and expected cost function between replacement are derived. An optimal policy is obtained that minimizes the average cost per unit time for preventive replacement, failure replacement, inspection and repair.

• 한국항공운항학회지
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• 제25권3호
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• pp.123-134
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• 2017

In order to advance into the MRO industry, the Aviation maintenance organization with suitable for the standards for personnel, facilities and operations should be first approved by FAA and EASA. The purpose of study is designed to arrange the standards required for personnel, facility, operation rule for approval of Repair Station maintenance organizations certified by FAA PART 145 of the US Federal Aviation Regulation. Also to consider the following differences through the comparative analysis with domestic AMO certification of the information in the Management, Maintenance Process, and Quality System for approval of maintenance organization authorized, the additional EASA PART 145. As a comparative analysis on maintenance organization certification in the country between FAA and EASA, this study could show us that domestic maintenance organization, certified manual contents are used by applying just many of the FAA system. And we could know that as part of the EASA maintenance organization certification process, airmen personnel were relatively systematically segmented and controlled. For domestic maintenance organization certification, operational as policy implications we would like to present policy implications such as the implication of rating system of Aviation Mechanic License like EASA, the financial support of the training center to resolve the shortage of the FAA or EASA license holders, operational organization as "CAMO" for systematic aviation mechanic certified system should be required, continued construction of hangar or MRO for airworthiness repair under Governmental support, and varied application of DER system from FAA accordingly.

• 산업경영시스템학회지
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• 제19권40호
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• pp.341-349
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• 1996

In this paper, we deal with the problem of maintenance policies for an air filter system in clean room. Two types of maintenance policies are considered, one based on the reliability of equipment and the other one determined by the total cost including minimal repair cost. For these models, we obtain the structure of the optimal maintenance Policy which minimize the total cost. Finally we give the numerical example.

• 한국신뢰성학회지:신뢰성응용연구
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• 제17권3호
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• pp.256-263
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• 2017

Purpose: This article provides the efficiency test results of conducting depot maintenance. Method: ANOVA (analysis of variance) and ANCOVA (analysis of covariance) tests are conducted using data obtained from Defense Logistics Integrated Information System (DELIIS). Results: The result shows that although the effect of the depot maintenance is significant, some parts do not follow the overall effect of the depot maintenance. In order to solve the problem we provide some suggestions to be improved. Conclusion: For improving the combat readiness condition of K-1 main battle tank, the maintenance policies and regulation must be revised for the parts of the weakness. In addition, the collection way of the operation and maintenance data must be redesigned.

• Structural Engineering and Mechanics
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• 제63권6호
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• pp.703-712
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• 2017

The composite blades of offshore wind turbines accumulate structural damage such as fatigue cracking due to harsh operation environments during their service time, leading to premature structural failures. This paper investigates various fatigue crack models for reproducing crack development in composite blades and proposes a stochastic approach to predict fatigue crack evolution and to analyse failure probability for the composite blades. Three typical fatigue models for the propagation of fatigue cracks, i.e., Miner model, Paris model and Reifsnider model, are discussed to reproduce the fatigue crack evolution in composite blades subjected to cyclical loadings. The lifetime probability of fatigue failure of the composite blades is estimated by stochastic deterioration modelling such as gamma process. Based on time-dependent reliability analysis and lifecycle cost analysis, an optimised maintenance policy is determined to make the optimal decision for the composite blades during the service time. A numerical example is employed to investigate the effectiveness of predicting fatigue crack growth, estimating the probability of fatigue failure and evaluating an optimal maintenance policy. The results from the numerical study show that the stochastic gamma process together with the proper fatigue models can provide a useful tool for remaining useful life predictions and optimum maintenance strategies of the composite blades of offshore wind turbines.

• 디지털융복합연구
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• 제8권1호
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• pp.1-10
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• 2010

2004년부터 정부는 기존 산업의 고도화를 위해 RFID/USN활용 지원사업을 단계적으로 추진해 왔다. 최근들어 일부 대기업을 중심으로 RFID/USN활용 성과들이 확인되고 있으나, 추가적인 산업정책 및 지원을 위한 기본적인 정책 자료가 부족한 실정이다. 이에 2008년도 시행된 27개의 시범사업을 대상으로 실 수혜기관의 만족도를 조사하여 RFID/USN의 구축단계, 활용단계(기술적 품질), 활용단계(업무적 품질), 그리고 유지보수단계 등 4단계에서의 만족도를 평가하고, 시사점을 도출하고자 하였다. 연구 결과, RFID/USN 기술의 안정성은 상당한 수준에 도달하였으나. 활용 및 확산을 위한 유지보수단계의 만족도가 가장 낮게 나타났다. 정책적 시사점으로 태그 및 기기의 저렴한 제공, 서비스 신뢰성 및 지속성을 위한 유지보수 컨소시엄 구성, RFID/USN 활용을 위한 수혜기업의 내부역량 강화 등 RFID/USN 유지보수 단계의 구체적인 정책지원등을 제시하였다.

• International Journal of Reliability and Applications
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• 제9권1호
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• pp.113-122
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• 2008

In this paper, we consider a periodic preventive maintenance policy in which each preventive maintenance reduces the hazard rate of amount proportional to the failure intensity, which increases since the system started to operate. And the effect of preventive maintenance at each preventive maintenance epoch is different. The expected cost rate per unit time for the proposed model is obtained. We discuss the optimal number N of the periodic preventive maintenance and the optimal period x, which minimize the expected cost rate per unit time and obtain the optimal preventive maintenance schedule for given cost structures of the model. A numerical example is given for the purpose of illustrating our results when the failure time distribution is Weibull distribution.

• 한국재난정보학회 논문집
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• 제16권2호
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• pp.276-290
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• 2020

연구목적: 국내 항만시설의 건설역사는 100년 이상 되었으며 최근 까지 현대적 시설이 지속적으로 건설되어 확장되고 있다. 그러나, 해양환경의 변화 및 물동량의 증가 등으로 초기 건설당시의 요구 성능조건을 유지하기는 쉽지 않다. 특히, 사용년수가 오래된 항만구조물의 경우, 선박의 대형화와 사용빈도 증가, 자연재해의 규모 증가등으로 안전성능과 기능관리가 매우 중요해져 가고 있다. 연구방법: 이에 본 연구는 항만시설의 구조형식별 상태변화를 조사하고 이를 기반으로 성능개선 및 수명연장활동에 기여하는 보수보강활동과 그 이력을 분석하였다. 연구결과: 항만시설 유지관리전략수립에 활용 가능한 성능개선비용(CAPEX)과 수선유지활동(OPEX)을 구별하고 이를 통한 유지관리전략수립에 활용 가능한 비용모델을 제시하였다. 결론: 이러한연구는 향후 시설물 중장기 투자의사결정에 큰 기여를 할 것으로 기대된다.

• 한국신뢰성학회:학술대회논문집
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• 한국신뢰성학회 2000년도 추계학술대회
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• pp.329-333
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• 2000

Delay time analysis is a pragmatic mathematical concept readily embraced by engineers which has been developed as a means to model maintenance decision problem. This paper considers an inspection period using delay time analysis for fishing vessel equipment. We assume that delay time distribution is Weibull and inspections are perfect. In this paper, we determine the optimal inspection period which minimize the expected downtime per unit time.

• 한국구조물진단유지관리공학회 논문집
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• 제8권4호
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• pp.185-193
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• 2004

현재의 교량의 유지관리 시에 적절한 보수 시기나 최적화된 유지관리 정책을 결정하기 위하여 교량의 성능저하를 정확히 예측하는 것은 가장 중요한 일이다 이률 위해 제안된 방법은 정량적 평가, 마르코프체인, 베이시안 추정법 등으로 구성되었다. 제안된 방법에 따라 국내의 콘크리트 슬래브 교량을 예로서 예측을 하여는데, 기존의 전문가 의견조사 빛 외관조사에 의한 예측보다 좀 더 합리적인 결과를 보여주었다.