• Journal of the Korean Data and Information Science Society
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• 제17권2호
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• pp.647-655
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• 2006

In this paper, we consider multiple comparisons for the ratio of the failure rates in two components system that the lifetimes of the components have independent exponential distributions. Also we suggest Bayesian multiple comparisons procedure based on fractional Bayes factor when noninformative priors are applied for the parameters. Finally, we give numerical examples to illustrate our procedure.

• 한국항공우주학회지
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• 제36권12호
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• pp.1186-1192
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• 2008

가스터빈 엔진 블레이드의 신뢰성을 해석하였다. 항복강도, 탄성계수, 엔진속도 및 기체온도를 서로 독립적인 확률변수로 가정하였다. 파손확률을 구하기 위하여 사용한 방법들 중에서 Advanced Mean Value Method가 가장 효율적임을 알 수 있었다. 동일한 평균과 표준편차를 갖는 정규, 대수정규 및 Weibull 분포로 확률변수 형상을 가정하였을 경우, 극한상태방정식의 누적분포함수는 확률변수 분포형상에 의하여 큰 영향을 받지 않음을 알 수 있었다. 확률변수의 표준편차에 대한 파손확률의 민감도는 기체온도의 경우에 가장 크다는 것을 알 수 있었다. 확률변수의 평균과 표준편차의 효과를 검토하였다. 기체온도의 평균과 엔진속도의 표준편차의 증가가 파손확률을 가장 크게 증가시킴을 알 수 있었다.

• 전자공학회논문지A
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• 제32A권8호
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• pp.1-10
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• 1995

We have analyzed the reliability of failure models in circuit-switched networks. These models are grid topology circuit-switched networks, and each node transmits a packet to a destination node using a Flooding routing method. We have assumed that the failure of each link and node is independent. We have considered two method to analyze reliability in these models : The Karnaugh Map method and joint probability method. In this two method, we have analyzed the reliability in a small grid topology circuit switched network by a joint probability method, and comared analytic results with simulated ones. For a large grid enormous. So, we have evaluated the reliability of the network by computer simulation techniques. As results, we have found that the analytic results are very close to simulated ones in a small grid topology circuit switched network. And, we have found that network reliability decreases exponentially, according to increment of link or node failure, and network reliability is almost linearly decreased according to increment of the number of links, by which call has passed. Finally, we have found an interesting result that nodes in a center of the network are superior to the other nodes from the reliability point of view.

• 한국안전학회지
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• 제12권4호
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• pp.161-168
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• 1997

Most plants producing semiconductors use a lot of chemicals, hazardous materials, and explosive gases. Though those materials are hazardous too much, some works still have to be done manually by human workers. However, according to a historical survey, more than half industrial accidents of those plants resulted from human errors or malfunctions. Thus, this research aimed 1) to diagnose shifting hazardous materials of semiconductor plants, 2) to estimate failure probability of human workers through human reliability analysis, and 3) to find out the tasks on which educational emphasis should be put. Through personal interview and visiting working spots, shifting tasks were analyzed, and modelled into a 24-step work, and after that, THERP and ETA was applied. During the shifting work, estimated human failure probability under the assumption of independency, 2.3004E-05, underestimated that probability 8. l008E-05 which could be calculated under the assumption of dependency. And this analysis showed that gas leakage from an old cylinder occupies 78.27% in the case of independent failures whereas gas leakage from a new cylinder occupies 75.06% in the case of dependent failures. So it was concluded that dependency assumption may gloss real situations. In addition, confirming gauge of regulators and closing valves turned out to be the most important tasks than purge tasks.

• 한국신뢰성학회지:신뢰성응용연구
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• 제6권2호
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• pp.187-194
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• 2006

In this paper, We presented the algorithm for estimating a reliability between nodes in wireless communication network such as RBN and MANET To estimate the reliability between nodes, we first modeled RNB and MANET as probability graph. Branches of the graph are always reliable and the probability of node failure is independent. After all possible simple path which can be established between two nodes are examined, we perform sharp arithmetic to remove repetition event between two nodes. Using probability for each variable of the minimized Boolean equation, we present the reliability formula.

• 한국신뢰성학회지:신뢰성응용연구
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• 제6권4호
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• pp.297-306
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• 2006

In this paper, We presented the algorithm for estimating a reliability between nodes in wireless distributed sensor networks (DSN). To estimate the reliability between nodes, we first modeled DSN as probability graph. Links of the graph are always reliable and the probability of node failure is independent. After all possible simple path which can be established between two nodes are examined, we perform sharp operation to remove repetition event between two nodes. Using probability for each variable of the minimized Boolean equation, we present the reliability formula.

• Journal of the Korean Data and Information Science Society
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• 제28권4호
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• pp.783-796
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• 2017

Bernoulli 시행은 시행 결과가 성공 (success) 혹은 실패 (failure)처럼 매 번의 시행에서 두 가지만 나오는 독립시행을 말한다. 가위바위보 게임과 같이 두 사람이 벌이는 연속적인 경기 인 경우 매번의 시합에서 둘 중 하나가 반드시 이기는 경우인 Bernoulli 시행이 아닌 게임도 존재한다. 각 종 게임의 경우 우리는 게임이 두 사람 중 한 사람이 게임을 이기고 끝날 때까 지의 게임의 지속시간과 두 사람 중 특정한 사람이 최종 승리할 확률에 관심을 갖는다. 본 연구에서는 두 사람이 벌이는 연속적인 게임에서 k번을 먼저 이기면 최종 승리하는 시합인 경우 매 시합에서 비기는 경우가 있는 시합과 비김이 없는 시합에 대하여 참가한 두 사람의 각 각 최종 승리할 확률과 시합이 끝날 때까지의 기대 게임수를 구하였다. 본 연구 결과를 이용 하면 비김이 있거나 없는 연속적인 게임의 경우 각 사람이 최종 승리할 확률 및 시합이 끝날 때까지의 기대 게임수를 구할 수 있다.

• International Journal of Reliability and Applications
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• 제6권2호
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• pp.117-133
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• 2005

Estimations of the parameters included in a two-component system are derived based on masked system life test data, when the probability of masking depends upon the exact cause of system failure. Also estimations of reliability for the individual components at a specified mission time are derived. Maximum likelihood and Bayes methods are used to derive these estimators. The problem is explained on a series system consisting of two independent components each of which has a Pareto distributed lifetime. Further we present numerical studies using simulation.

• 대한전기학회논문지:전력기술부문A
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• 제52권7호
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• pp.401-406
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• 2003

Electric power industries in several countries are currently undergoing major changes, mainly represented by the privatizations of the power plants and distribution systems. Reliable operations of the power plants directly contribute to the revenue increases of the generation companies in such competitive environments. Strategic optimizations should be performed between the levels of the reliabilities to be maintained and the various preventive maintenance costs, which require the accurate estimations of the power plant reliabilities. However, accurate estimations of the power plant reliabilities are often limited by the lack of accurate power plant failure data. A power plant is not supposed to be failed that often. And if it fails, its impact upon the power system stability is quite substantial in most cases, setting aside the significant revenue losses and lowered company images. Reliability assessment is also important for Independent System Operators(ISO) or Market Operators to properly assess the level of needed compensations for the installed capacity based on the availability of the generation plants. In this paper, we present a power plant reliability estimation technique that can be applied when the failure data is insufficient. Median rank and Weibull distribution are used to accommodate such insufficiency. The Median rank is utilized to derive the cumulative failure probability for each ordered failure. The Weibull distribution is used because of its flexibility of accommodating several different distribution types based on the shape parameter values. The proposed method is applied to small size failure data and its application potential is demonstrated.

• International Journal of Reliability and Applications
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• 제2권4호
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• pp.253-262
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• 2001

A k-out-of-n standby system is considered where all of its components are s-independent and classified either working or cold standby connected with imperfect switches. The probability density function of the life length for this system is established in closed form, when the underlying components have constant failure rates. Also the reliability function of the system is derived. Finally, the reliability functions for one, two and three out of four systems are deduced for perfect or imperfect switches and identical or non-identical constant failure rates for working and standby components.