• 한국해양공학회지
• /
• 제27권2호
• /
• pp.47-52
• /
• 2013

A subsea chemical injection system treats blockage problems in a subsea production system. It is important to treat problems quickly, because production delays cause fatal profit losses in a subsea production system. Therefore, the subsea industry requires a relatively higher reliability level for a production system compared to other industries. In this study, a subsea chemical injection system (linked to a control system) to inject chemicals into a subsea X-mas tree was analyzed. By using FSA (Formal Safety Assessment), the risk factors were defined and a quantitative risk analysis utilizing FTA (Fault Tree Analysis) and ETA (Event Tree Analysis) was performed. As a result, the effectiveness of a risk reduction option was evaluated.

• 한국정보통신학회논문지
• /
• 제19권8호
• /
• pp.1981-1989
• /
• 2015

최근 전투 시스템의 신뢰성을 통합적으로 분석하는 것에 관한 연구의 필요성이 강조되고 있으며, 이와 관련하여 전투 시스템 신뢰성 분석 시스템의 개발 요구가 생겨나게 되었다. 이러한 이유로 본 논문에서는 시스템의 고장 원인 및 확률 분석을 위한 대표적인 신뢰성 분석 기법인 FTA를 적용하여 이를 기반으로 전차의 취약성을 분석하는 시스템을 개발하는 것에 관한 내용을 다룬다. 이를 위해 FTA를 전투 시스템의 취약성 분석에 적용하기 위한 방법을 제안하였으며, 제안한 방법을 기반으로 FTA 기반의 전차 취약성 분석 시스템을 개발하였다. 개발한 시스템은 3차원 전차 모델을 기반으로 다중 관통선을 설정하여 주요 부품의 피격 확률을 도출하고, 이를 통해 기능별 상실 확률을 분석한다. 분석된 기능별 상실 확률을 통해 피격면에 따른 전차의 취약성을 분석할 수 있다.

• 한국수소및신에너지학회논문집
• /
• 제26권2호
• /
• pp.192-198
• /
• 2015

Fault Tree Analysis to predict the lifetime in the design process of LNG compressor is considered. Fault Trees for P & ID of the compressor are created. Individual components that comprise the compressor are configured with the basic event. The failure rates in the PDS and OREDA are applied. As results, the system failure rate and the reliability over time are obtained. Further, the power transmission and the shaft seal system is confirmed to confidentially importantly contribute to the overall lifetime of the system. These techniques will help to improve the reliability of design of large scale machinery such as a plant.

• 한국정보시스템학회지:정보시스템연구
• /
• 제17권3호
• /
• pp.25-37
• /
• 2008

In a fault tree analysis, an uncertainty importance measure is often used to assess how much uncertainty of the top event probability (Q) is attributable to the uncertainty of a basic event probability ($q_i$), and thus, to identify those basic events whose uncertainties need to be reduced to effectively reduce the uncertainty of Q. For evaluating the measures suggested by many authors which assess a percentage change in the variance V of Q with respect to unit percentage change in the variance $v_i$ of $q_i$, V and ${\partial}V/{\partial}v_i$ need to be estimated analytically or by Monte Carlo simulation. However, it is very complicated to analytically compute V and ${\partial}V/{\partial}v_i$ for large-sized fault trees, and difficult to estimate them in a robust manner by Monte Carlo simulation. In this paper, we propose a method for evaluating the measure using discretization technique and Monte Carlo simulation. The proposed method provides a stable uncertainty importance of each basic event.

• 한국가스학회지
• /
• 제1권1호
• /
• pp.81-86
• /
• 1997

본 연구에서는 다양한 위험성 평가 방법중에서 사고의 발생 경위를 연역적으로 추론해 나가는 이상 트리 분석 방법을 이용하여 정상사상을 일으킬 수 있는 시스템 요소들의 파악으로부터 화학공장의 사고 발생 가능성을 산정하였다. Gate-by-gate 방법과 최소 컷 ? 방법을 이용하여 공장내 존재하는 잠재위험에 대하여 정성적 및 정량적 위험성 평가를 수행하였다. 정량적인 위험성 평가 단계에서는 시스템 요소의 고장률 또는 신뢰율 자료로부터 정상사상의 사고 발생 확률 및 빈도를 계산하였다 결론적으로 이상 트리 분석방법을 이용하여 시스템/공정의 사고 발생확률을 논리 방식으로 계산할 수 있었으며, 중요도 분석을 이용하여 정상 사상이 발생하는데 가장 큰 영향을 미치는 손실 경로를 확인하여 보았다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2008년도 추계학술대회 논문집 전력기술부문
• /
• pp.247-249
• /
• 2008

배전계통은 수용가에 전력을 공급하는 설비로서 계통의 안정적인 운영을 위하여 배전계통의 신뢰도를 산정하는 것은 중요한 의미를 갖는다. 본 논문에서는 배전계통을 구성하는 설비와 수용가의 전력 공급 유무에 따른 신뢰도를 산정하였다. Fault Tree Analysis(FTA)는 시스템의 고장을 해석하는 방법으로 사용된다. 시스템의 고장을 발생시키는 사건원인을 분석하여 Fault Tree(FT: 고장목)를 작성하고, 시스템을 구성하는 설비들의 고장확률 계산을 통하여 전 시스템의 신뢰성을 산정할 수 있다. 본 연구에서는 Relex 7.7 프로그램을 사용하여 FTA를 수행하였다.

• 대한조선학회논문집
• /
• 제59권3호
• /
• pp.164-172
• /
• 2022

A HAZID is a brainstorming workshop to identify hazards in an early phase of a project. It should be flexible to capture all probable accidents allowing experienced participants to exploit their expertise and experiences. A bowtie analysis is a graphical representation of major accident hazards elaborating safety measures i.e. barriers. The result of these workshops should be documented in an organized manner to share as good as possible details of the discussion through the lifetime of the project. Currently results are documented using a three-step representation of an accident; causes, top event and consequences, which cannot capture correctly sequence of events leading to various accidents and roles of barrier between two events. Another problem is that barriers would be shown repeatedly leading to a misunderstanding that there are an enough number of safety measures. A new bowtie analysis method is proposed to describe an accident in multiple steps showing relations among causes or consequences. With causes and consequences shown in a format of a tree, the frequencies of having the top event (Fault tree analysis) and various consequences (Event tree analysis) are evaluated automatically based on the frequency of initiating causes and the probabilities of failure of barriers. It will provide a good description of the accident scenario and help the risk to be assessed transparently.

• 산업경영시스템학회지
• /
• 제40권2호
• /
• pp.41-50
• /
• 2017

The purpose of this paper is to improve the service tree analysis introduced recently by Geum et al. [15]. Service tree analysis structures the service based on the customer participation perspective and provides a qualitative analysis method categorizing the service elements on the basis of its impact to top service. This paper attempts to apply the concept of reliability importance to the service tree analysis as a perspective of quantitative analysis, which is considered little in Geum et al. [15]. Reliability importance is a measure of the structural impact of the components that make up the system on the system lifetime in reliability engineering field and often used in fault tree analysis. We transform the reliability importance into service importance in accordance with service tree analysis, so that the influence of service elements on the service can be judged and compared. The service importance is defined as the amount of change of the service according to the change of the service element, therefore, it can be utilized as an index for determining a service element for service improvement. In addition, as an index for paired service elements, the relationship between the two service components can be measured by joint service importance. This paper introduces conceptual changes in the process of applying reliability importance to service analysis, and shows how to use the service importance for identifying the priority of service element for the final service and improving customer satisfaction through an example. By using the service importance and joint service importance in service tree analysis, it is possible to make efficient decision making in the process of determining the service elements for analyzing and improving the service.

• 한국멀티미디어학회논문지
• /
• 제18권11호
• /
• pp.1342-1350
• /
• 2015

Due to rapid development of mobile device technologies, the mobile banking through Internet has become a major service of banking information systems as a security-critical information systems. Recently, lots of mobile banking information systems which handle personal and transaction information have been exposed to security threats in vulnerable security control and management processes, mainly software systems. Therefore, in this paper, we propose a process model for software security improvements in mobile banking information system by application of fault tree analysis(FTA) and failure modes and effects analysis(FMEA) on the most important activities such as 'user authentication' and 'access control' and 'virus detection and control' processes which security control and management of mobile banking information systems are very weak.

• 산업기술연구
• /
• 제26권B호
• /
• pp.145-155
• /
• 2006

High level of reliability in facility operation is specifically required these days. The goal of this study is to secure a methodology for reliability analysis of hydro-power plant so that an appropriate decision for operation and investment can be made. Fault tree analysis of water supply system within hydro-power plant has been performed in this study. We briefly examined the electric power generation facility and water supply system. We then developed fault tree for the water supply system based on failure modes and effects analysis. We conclude this study and provided future research areas.