• 한국신뢰성학회:학술대회논문집
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• 한국신뢰성학회 2001년도 정기학술대회
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• pp.257-263
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• 2001

In the analysis of product reliability, the fault tree is widely used since it shows the interrelations of the faults that lead to the product fault. A top-down approach based on experts’ experience is commonly used in the fault tree construction and the trees often take different forms depending on the intent of the analyst. In this work it is studied how to construct fault trees with the utilization of function trees obtained from analyzing the functions and sub-functions of products in order to suggest a generic way of fault tree construction. The function tree of a product is obtained by analyzing basic functions comprising the product main function in a bottom-up approach so that it enables to construct an objective fault tree. The fault tree for a scroll compressor is shown as an example.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.401-406
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• 2000

Fault tree analysis (FTA) is a widely used methodology for reliability analysis. The method is useful in that it suggests a very comprehensive way of describing the hierarchical relations of causes of faults and the corresponding results. However it is difficult to get appropriate fault trees for given products or systems without very profound knowledge and experience. This work aims to develop a methodology of fault tree construction using the results of function deployment for machine parts, which provides an objective way of preparing fault trees. The failure modes are defined to each function network generated by the function deployment method and the fault tree with respect to each viewpoint is constructed by arranging the failure modes. The fault tree is finally obtained by synthesizing the fault trees with respect to each viewpoint. The example of fault tree construction is also shown.

• Journal of Advanced Marine Engineering and Technology
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• 제28권7호
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• pp.1092-1100
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• 2004

This paper describes the application of fault tree technique to analyze of compressor failure. Fault tree analysis technique involves the decomposition of a system into the specific form of fault tree where certain basic events lead to a specified top event which signifies the total failure of the system. In this research. fault trees for failure analysis of screw type air compressor are made. This fault trees are used to obtain minimal cut sets from system failure and system failure rate for the top event occurrence can be calculated. It is Possible to estimate air compressor reliability by using constructed fault trees through compressor failure example. It is Proved that FTA is efficient to investigate the compressor failure modes and diagnose system.

• 한국콘텐츠학회논문지
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• 제11권10호
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• pp.49-58
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• 2011

결함 트리 분석(Fault Tree Analysis)은 결함 트리를 구축하여 시스템의 안전성 분석을 수행한다. 그러나 결함 트리를 구성하는 작업은 대상 시스템의 도메인에 대한 지식과 경험을 필요로 하며 많은 시간과 노력을 소요한다. 이 논문에서는 시스템 설계 산출물인 상태 전이 모델을 기반으로 결함 트리를 체계적으로 구성하는 방법을 제안한다. 이를 위해 시스템 상태 전이 모델의 안정성 확보에 필요한 조건들을 식별하고 결함 트리를 구성할 수 있는 템플리트를 개발한다. 이 논문에서는 제안된 방법을 철도 건널목 제어 시스템에 적용한 결과도 기술한다.

• 한국정보과학회논문지:소프트웨어및응용
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• 제29권12호
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• pp.860-872
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• 2002

폴트 트리 분석(Fault Tree Analysis)은 산업계에서 가장 널리 사용되는 안전성 분석 기법 중의 하나이다. 하지만, 이 기법은 보통 수작업으로 이루어지며, 분석 결과를 체계적이고 자동적으로 검증할 수 있는 방법이 없다는 약점을 지닌다. 본 논문에서는 실시간 모델 체커인 UPPAAL을 이용하여 안전성이 중요한 소프트웨어의 요구 사항들을 정형 명세하고, 수작업으로 찬성된 폴트 트리의 정확성을 검증하는 방법을 제안하고 있다. 제안된 방법을 유용성을 확인하기 위해서 월성 원자력 발전소의 비상 정지 소프트웨어(Wolsung SDS2)에서 사용된 기능 요구 사항들을 예제로서 사용하였다. 폴트 트리는 월성 SDS2에 대한 전문적인 지식을 지니고 폴트 트리를 이용한 안전성 분석을 여러 번 수행해 본 경험이 있는 대학원생들에 의해 작성되었다. 기능 요구 사항들은 UPPAAL의 입력으로서 사용되기 위해서 시제 오토마타의 형태로 수작업으로 변환되었으며, 이 폴트 트리의 정확성을 검증하기 위해서 모델 체킹을 사용하였다 본 논문에서 제안된 방법을 월성 SDS2 예제에 적용해 본 결과, 수작업으로 작성된 폴트 트리에 존재하는 오류를 찾을 수 있었으며, 이러한 작업을 통하여 제안된 방법이 폴트 트리 분석에 대한 신뢰도를 높이는데 유용함을 발견하였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2006년도 추계학술대회 논문집
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• pp.1132-1139
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• 2006

Railway risk is evaluated by a method of linking event trees and fault trees as the general PSA(Probabilistic Safety Assessment) model for the risk assessment of complex systems. Accident scenarios causing undesirable events are modeled by event trees comprised of several accident sequences. Each branch located in the accident progression of the event tree is modeled by an fault tree or can be represented by some value too simply. We usually evaluate the frequency of the whole sequence by adding them after calculating the frequency of each sequence at a time. However, since there are quite a number of event trees and fault trees in the railway risk assessment model, the number of sequence to evaluate increases and preparation for the risk assessment costs much time all the more. Also, it may induce errors when analysts perform the work of quantification. Therefore, the systematic maintenance and control of event trees and fault trees will be essential for the railway risk assessment. In this paper we introduce an integrated assessment method using one-top model and develop a risk assessment tool for the maintenance and control of the railway risk model.

• 대한기계학회논문집
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• 제18권1호
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• pp.127-138
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• 1994

The application of fault tree technique to the analysis of compressor failure is considered. The techniques involve the decomposition of the system into a form of fault tree where certain basic events lead to a specified top event which signifies the total failure of the system. In this paper, fault trees are made by using fault train of screw type air compressor failure. The fault trees are used to obtain minimal cut sets from the modes of system failure and, hence the system failure rate for the top event can be calculated. The method of constructing fault trees and the subsequent estimation of reliability of the system is illustrated through compressor failure. It is proved that FTA is efficient to investigate the compressor failure modes and diagnose system.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1993년도 춘계학술대회 논문집
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• pp.305-309
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• 1993

The application of fault tree technique to the analysis of compressor failure is considered. The techniques involve the decomposition of the system into a logic diagram or fault tree in whichcertain basic or primary events lead to a specified top event which signifiss the total failure of the system. The fault trees are used to obtain miniumal cut sets from whichthe modes of system failure and, hence the reliability for the top event can be calculated. The method of constructing fault trees and the subsequent estimation of reliability of the system is illustrated through a compressor failure. FTA is roved to be efficient to investigate the compressor fault train.

• 한국정보통신학회논문지
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• 제20권3호
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• pp.654-662
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• 2016

사고수목을 이루는 게이트나 기본사상이 많아질수록 정상사상 확률의 정확한 계산이 어려워진다. 이를 극복하기 위해 BDD 방법을 적용하면 중소형 사고수목의 경우 짧은 시간에 근사계산 없이 정확한 값을 구할 수 있다. CUDD 함수를 이용하여 사고수목을 BDD로 변환하고 그로부터 정상사상의 발생확률을 구하는 고장경로 탐색 알고리즘을 고안하였다. 후방탐색 알고리즘은 전방탐색 알고리즘보다 고장경로의 탐색과 확률계산 시간에서 효과적이다. 이 탐색 알고리즘은 BDD에서 고장경로를 찾는데 있어서 탐색시간을 줄일 수 있고, 해당 사고수목의 단절집합과 최소단절집합을 찾는 유용한 방법이다.

• Nuclear Engineering and Technology
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• 제53권9호
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• pp.2888-2898
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• 2021

Vital area identification (VAI) is an essential procedure for the design of physical protection systems (PPSs) for nuclear power plants (NPPs). The purpose of PPS design is to protect vital areas. VAI has been improved continuously to overcome the shortcomings of previous VAI generations. In first-generation VAI, a sabotage fault tree was developed directly without reusing probabilistic safety assessment (PSA) results or information. In second-generation VAI, VAI model was constructed from all PSA event trees and fault trees. While in third-generation VAI, it was developed from the simplified PSA event trees and fault trees. While VAIs have been performed for NPPs in full-power operations, VAI for NPPs in low-power and shutdown (LPSD) operations has not been studied and performed, even though NPPs in LPSD operations are very vulnerable to sabotage due to the very crowded nature of NPP maintenance. This study is the first to research and apply VAI to LPSD operation of NPP. Here, the third-generation VAI method for full-power operation of NPP was adapted to the VAI of LPSD operation. In this study, LPSD VAI for a few plant operational states (POSs) was performed. Furthermore, the operation strategy of vital areas for both full-power and LPSD operations was discussed. The LPSD VAI method discussed in this paper can be easily applied to all POSs. The method and insights in this study can be important for future LPSD VAI that reflects various LPSD operational states. Regulatory bodies and electric utilities can take advantage of this LPSD VAI method.