• International Journal of Reliability and Applications
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• 제15권1호
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• pp.51-64
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• 2014

This paper develops a warranty cost model for complex systems with imperfect repair within a warranty period by addressing a practical case that the first inter-failure interval is longer than any other inter-failure intervals. The product is in its best condition before the first failure if repair is imperfect. After the imperfect repair, other inter-failure intervals which are explained by renewal processes, are stochastically smaller than the first inter-failure interval. Based on this idea, we suggest the failure-interval-failure-criterion model. In this model, we consider two random variables, X and Y where X represents failure intervals and Y represents failure criterion. We also obtain the distribution of the number of failures and conduct the warranty cost analysis. We investigate different types of warranty cost models, reliabilities and other measures for various systems including series-parallel configurations. Several numerical examples are discussed to demonstrate the applicability of the methodologies derived in the paper.

• 전기학회논문지
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• 제58권11호
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• pp.2122-2127
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• 2009

This study presents the failure rate and repair rate of Superconducting Fault Current Limiter(SFCL) and adjacent distribution equipments. When the fault current penetrated SFCL, the supply of electric power to the customers can be partly continued. It is expected that SFCL makes to improve the reliability index of customers. Contrary to the expectations, the series connection between SFCL and distribution system could deteriorate the reliability index. To evaluate the reliability index in the distribution system including SFCL, the failure rate and repair rate of SFCL are required as well as that of distribution equipments. Also, the insertion of SFCL makes to change the failure rate and repair rate of adjacent equipments. This study proposes a method to calculate the failure rate and repair rate of a component combining SFCL and adjacent equipments.

• 한국항만경제학회지
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• 제40권1호
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• pp.61-70
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• 2024

세계 수리조선 시장 규모가 급격히 확대되고 다변화 추세가 지속되고 있는 가운데, 국내 수리조선업은 높은 기술 수준 대비 높은 기술 수준 대비 인프라 부족, 신조 시장 집중, 기술 인력 고령화, IT 시스템 부재, 기업의 영세성의 이유로 경쟁력을 상실하고 있다. 국내 수리조선업의 정보화 수준은 타 산업 군 대비 매우 낮은 수준으로 정보시스템 개발에 대한 시도는 있었지만, 성공한 사례는 흔치 않다. 따라서 본 연구의 목적은 부산지역의 수리조선업을 영위하고 있는 기업을 대상으로 설문조사를 통하여 수리조선업의 정보화 관점에서의 전략통합 및 조직통합의 필요성을 파악하고자 한다. 그 후 부산지역 수리조선소 주요 업체와의 대면인터뷰를 통하여 수리조선업의 정보시스템 발전 방향을 도출하였다. 본 연구의 결과는 향후 수리조선업 디지털 전환 필요성을 제고하고, 정보시스템 구축 및 적용 과정에 있어 유의미한 방향을 제공할 것으로 판단된다.

• 한국컴퓨터정보학회논문지
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• 제9권2호
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• pp.63-68
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• 2004

본 연구는 기업이나 공공단체 학교 등 대량의 PC를 보유하고 있는 곳에서 PC의 고장에 대한 효율적이고, 체계적인 유지보수 기능을 갖는 시스템의 개발과 운영을 설계하였다. 네트워크 유지보수 계약에 활발히 사용되고 있는 서비스 수준 협약(Service Level Agree : SLA) 기법을 활용하여 서비스 제공자의 서비스 제공 수준에 대한 투명한 측정과 관리를 할 수 있게 설계하였으며, 서비스 요구 점수, 유지보수 활동, 사용자 만족도, 확인 과정에 이르기까지 서비스의 전체 과정이 하나의 시스템에서 이루어지도록 One Stop Service가 가능하도록 시스템을 설계하였다.

• 한국신뢰성학회지:신뢰성응용연구
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• 제14권2호
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• pp.122-128
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• 2014

In this paper, we consider the periodic preventive maintenance model for a repairable system following the expiration of extended warranty under replacement-repair warranty. Under the replacement-repair warranty, the failed system is replaced or minimally repaired by the manufacturer at no cost to the user. Also, under extended warranty, the failed system is minimally repaired by the manufacturer at no cost to the user during the original extended warranty period. As a criterion of the optimality, we utilize the expected cost rate per unit time during the life cycle from the user's perspective. And then we determine the optimal preventive maintenance period and the optimal preventive maintenance number by minimizing the expected cost rate per unit time. Finally, the optimal periodic preventive maintenance policy is given for Weibull distribution case.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1993년도 가을 학술발표회 논문집
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• pp.71-78
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• 1993

The R/C structures is very popular because of its low construction cost and its semi-permanent life. But in Korea, unfortunately there are few exprets in this field, and the repair methods and selection of material for R/C structures are determined by their subjective personal opinions. Therefore systematic study of this field is ulgently required. For attainning this purpose, in this study the related documents and knowledge or experience from human experts were collected. Based on the collected information cracks are classified into 25 patterns and repair related-knowledge base, which will be formulated and encoded into the domain knowledge, is built. And then an expert system, that can suggest the repair methods in the same way the human experts would, is developed. The results using the developed expert system are compared to the real field practices and they are satisfactory.

• 경영과학
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• 제26권1호
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• pp.209-223
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• 2009

In this paper, an analysis problem of repair levels and spare part allocation for MIME(Multi indenture multi echelon) systems is studied using simulation and meta-heuristics. We suggest a method to determine simultaneously repair levels and spare parts allocation to minimize the life cycle cost of MIME system under availability constraint. A simulated annealing method is used to analyze the repair levels and genetic algorithm is used to obtain the optimal allocation of spare parts. We also develop a simulation system to calculate the life cycle cost and system availability. Some numerical examples are also studied.

• 한국컴퓨터정보학회지
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• 제12권1호
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• pp.21-27
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• 2004

본 연구는 기업이나 공공단체, 학교 등 대량의 PC를 보유하고 있는 곳에서 PC의 고장에 대한 효율적이고, 체계적인 유지보수 기능을 갖는 시스템의 개발과 운영을 설계하였다. 네트워크 유지보수 계약에 활발히 사용되고 있는 서비스 수준 협약(Service Level Agree : SLA) 기법을 활용하여 서비스 제공자의 서비스 제공 수준에 대한 투명한 측정과 관리를 할 수 있게 설계하였으며, 서비스 요구 점수, 유지보수 활동, 사용자 만족도, 확인 과정에 이르기까지 서비스의 전체 과정이 하나의 시스템에서 이루어지도록 One Stop Service가 가능하도록 시스템을 설계하였다.

• 산업경영시스템학회지
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• 제33권2호
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• pp.170-175
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• 2010

Maintaining a complex repairable system can be achieved by repairing, replacing, or any other activities. This paper proposes a joint optimization policy that is composed with ordering and replacing under minimal repair for the complex system. For this purpose, we derive the expected cost due to the minimal repair, ordering, downtime, inventory costs, and salvage value of units that follow generally distribution. Some properties about the optimum ordering policy that are suggested for our purpose shows that the optimum ordering policy minimizing the expected cost is either one of the two typical policies : (1) the original unit is replaced as soon as the ordered spare is delivered, or (2) the delivered spare is used as inventory part until the original unit fails.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 춘계학술발표회논문집(2)
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• pp.691-698
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• 1996

This paper propose a procedure to estimate the system lifetime distribution using simulation method in a parametric framework and also develop the criterion for terminating the simulation. We assume that a system is composed of many components whose lifetime and repair time distributions are general, and repair of each component is imperfect or not. General simulation algorithms can not be adopted for this case, due to the dependency of successive operating times and the discontinuity in base line intensity function of failure process. Then we propose algorithms for generating failure times subject to imperfect repair. We develop the event time tracking logic for identifying the system failure time, and also develop the criterion for terminating the simulation. Our procedure is composed of two phases. The first phase of the procedure is to generate the system failure times from the inputs. The second phase is to estimate the lifetime distribution of the system. The best model is selected by a fully automated procedure among well-known parametric families, and the required parameters are estimated. We give examples to show the accuracy of our procedure and the effect of repair effect of components to system MTTF(Mean Time To Failure).