• 제목/요약/키워드: fault-effect tree

검색결과 56건 처리시간 0.023초

PMMA수지의 수 Tree현상

  • 유근민;이재선
    • 한국통신학회논문지
    • /
    • 제7권1호
    • /
    • pp.18-24
    • /
    • 1982
  • 高分子材料에서 水分의 영향으로 發生되는 Tree를 硏究할 目的으로 熱的, 化學的으로 安定된 Al2,O2 및 SiO2 徵紛을 添加하여 材에 미치는 영향을 考察하였다.

무인기용 발사장비의 추진와이어 파단 및 구조변형 방지를 위한 형상변경 사례 (A Case Study on Configuration Change for Preventing Propulsion Wire Fracture and Structural Deformation of Launch System of UAV)

  • 임다훈;박경환
    • 품질경영학회지
    • /
    • 제50권3호
    • /
    • pp.533-543
    • /
    • 2022
  • Purpose: The purpose of this study is to identify and resolve the causes of defects in the unmanned aerial vehicle launch system(propulsion wire fracture, rear rail deformation) and to prevent recurrence. Methods: The causes of the two defects were derived through fault tree analysis for each of the two defects and fault reproduction tests. In the case of propulsion wire, the installation of a high speed camera to check the behavior of wire was the driving force behind the defect resolution. Results: The results of this study are as follows; It was determined that the thickness of the washer was less than the maximum tolerance of the pulley was the cause of the propulsion wire fracture defect. Failure to comply with the launch procedure and insufficient safety margin were judged as the cause of the rear rail deformation defect. Accordingly, the configuration was changed to remove each defect. Conclusion: The case of this study was conducted to eliminate defects in the launch system for UAV. The causes of defects were estimated through fault tree analysis. After the configuration change, Structural analysis and launch tests were performed to demonstrate the safety and effectiveness of the modified configuration. As a result, the effect of the modified configuration was verified.

SIL4 안전관련 시스템에 적합한 출력 모듈의 구조 설계에 대한 연구 (A Study on Architecture Design of Output Module for SIL4 Safety Related System)

  • 유등열;황경환;이기서
    • 한국전자통신학회논문지
    • /
    • 제10권10호
    • /
    • pp.1079-1086
    • /
    • 2015
  • 본 논문은 안전 무결성 레벨이 4(: Safety Integrity Level 4)인 안전 관련 시스템에 적합한 출력 모듈의 구조를 설계하였고, 설계된 출력 모듈에 요구되는 정량적 목표치의 수준을 제시하였다. 특히 다양한 출력 방식 중에서 릴레이 출력 신호와 아날로그 신호로 구성된 출력 모듈이 안전 기능을 수행하는 시스템의 구성 요소인 경우를 적용하였다. 분석 방법은 FMEA(: Failure Modes and Effect Analysis), FTA(: Fault Tree Analysis) 방식을 이용하였다. 그 결과로 철도 응용 규격인 IEC 62425의 요구사항을 준수하는 SIL4 안전 관련 시스템의 출력 모듈의 구조와 고장빈도인 정량적 목표치를 제시하였다.

대형 수소 액화 플랜트의 정량적 위험도 평가에 관한 연구 (Study on a Quantitative Risk Assessment of a Large-scale Hydrogen Liquefaction Plant)

  • 도규형;한용식;김명배;김태훈;최병일
    • 한국수소및신에너지학회논문집
    • /
    • 제25권6호
    • /
    • pp.609-619
    • /
    • 2014
  • In the present study, the frequency of the undesired accident was estimated for a quantitative risk assessment of a large-scale hydrogen liquefaction plant. As a representative example, the hydrogen liquefaction plant located in Ingolstadt, Germany was chosen. From the analysis of the liquefaction process and operating conditions, it was found that a $LH_2$ storage tank was one of the most dangerous facilities. Based on the accident scenarios, frequencies of possible accidents were quantitatively evaluated by using both fault tree analysis and event tree analysis. The overall expected frequency of the loss containment of hydrogen from the $LH_2$ storage tank was $6.83{\times}10^{-1}$times/yr (once per 1.5 years). It showed that only 0.1% of the hydrogen release from the $LH_2$ storage tank occurred instantaneously. Also, the incident outcome frequencies were calculated by multiplying the expected frequencies with the conditional probabilities resulting from the event tree diagram for hydrogen release. The results showed that most of the incident outcomes were dominated by fire, which was 71.8% of the entire accident outcome. The rest of the accident (about 27.7%) might have no effect to the population.

A Quantitative Study on Important Factors of the PSA of Safety-Critical Digital Systems

  • Kang, Hyun-Gook;Taeyong Sung
    • Nuclear Engineering and Technology
    • /
    • 제33권6호
    • /
    • pp.596-604
    • /
    • 2001
  • This paper quantitatively presents the effects of important factors of the probabilistic safety assessment (PSA) of safety-critical digital systems. The result which is quantified using fault tree analysis methodology shows that these factors remarkably affect the system safety. In this paper we list the factors which should be represented by the model for PSA. Based on the PSA experience, we select three important factors which are expected to dominate the system unavailability. They are the avoidance of common cause failure, the coverage of fault tolerant mechanisms and software failure probability. We Quantitatively demonstrate the effect of these three factors. The broader usage of digital equipment in nuclear power plants gives rise to the safety problems. Even though conventional PSA methods are immature for applying to microprocessor-based digital systems, practical needs force us to apply it because the result of PSA plays an important role in proving the safety of a designed system. We expect the analysis result to provide valuable feedback to the designers of digital safety- critical systems.

  • PDF

자기검사회로를 이용한 대기이중계구조 결함허용제어기의 설계 및 신뢰도평가에 관한 연구 (A Study on Design and Reliability Assessment for Embedded Hot-Standby Sparing FT System Using Self-Checking Logic)

  • 이재호;이강미;김용규;신덕호
    • 한국철도학회논문집
    • /
    • 제9권6호
    • /
    • pp.725-731
    • /
    • 2006
  • Hot Standby sparing system detecting faults by using software, and being tolerant any faults by using Hardware Redundancy is difficult to perform quantitative reliability prediction and to detect real time faults. Therefore, this paper designs Hot Standby sparing system using hardware basis self checking logic in order to overcome this problem. It also performs failure mode analysis of Hot Standby sparing system with designed self checking logic by using FMEA (Failure Mode Effect Analysis), and identifies reliability assessment of the controller designed by quantifying the numbers of failure development by using FTA (Fault Tree Analysis)

Off-Site 패키지형 수소충전소의 FTA 분석 (A Study on FTA of Off-Site Packaged Hydrogen Station)

  • 서두현;김태훈;이광원;최영은
    • 한국수소및신에너지학회논문집
    • /
    • 제31권1호
    • /
    • pp.73-81
    • /
    • 2020
  • For the fault tree analysis (FTA) analysis of the packaged hydrogen filling station, the composition of the charging station was analyzed and the fault tree (FT) diagram was prepared. FT diagrams were created by dividing the causes of events into external factors and internal factors with the hydrogen event as the top event. The external factors include the effects of major disasters caused by natural disasters and external factors as OR gates. Internal factors are divided into tube tailer, compressor & storage tank, and dispenser, which are composed of mistakes in operation process and causes of accidents caused by parts leakage. In this study, the purpose was to improve the hydrogen station. The subjects of this study were domestic packaged hydrogen stations and FTA study was conducted based on the previous studies, failure mode & effect analysis (FMEA) and hazard & operability study (HAZOP). Top event as a hydrogen leaking event and constructed the flow of events based on the previous study. Refer to "Off shore and onshore reliability data 6th edition", "European Industry Reliability Data Bank", technique for human error rate prediction (THERP) for reliability data. We hope that this study will help to improve the safety and activation of the hydrogen station.

Computer-Aided Decision Analysis for Improvement of System Reliability

  • Ohm, Tai-Won
    • 대한안전경영과학회지
    • /
    • 제2권4호
    • /
    • pp.91-102
    • /
    • 2000
  • Nowadays, every kind of system is changed so complex and enormous, it is necessary to assure system reliability, product liability and safety. Fault tree analysis(FTA) is a reliability/safety design analysis technique which starts from consideration of system failure effect, referred to as “top event”, and proceeds by determining how these can be caused by single or combined lower level failures or events. So in fault tree analysis, it is important to find the combination of events which affect system failure. Minimal cut sets(MCS) and minimal path sets(MPS) are used in this process. FTA-I computer program is developed which calculates MCS and MPS in terms of Gw-Basic computer language considering Fussell's algorithm. FTA-II computer program which analyzes importance and function cost of VE consists. of five programs as follows : (l) Structural importance of basic event, (2) Structural probability importance of basic event, (3) Structural criticality importance of basic event, (4) Cost-Failure importance of basic event, (5) VE function cost analysis for importance of basic event. In this study, a method of initiation such as failure, function and cost in FTA is suggested, and especially the priority rank which is calculated by computer-aided decision analysis program developed in this study can be used in decision making determining the most important basic event under various conditions. Also the priority rank can be available for the case which selects system component in FMEA analysis.

  • PDF

수소 충전소에 대한 정량적 안전성 평가 (Quantitative Safety Assessment for Hydrogen Station)

  • 성대현;이광원;김태훈;오동석;오영달;서두현;김영규;김은정
    • 한국안전학회지
    • /
    • 제27권3호
    • /
    • pp.111-116
    • /
    • 2012
  • This study is about the quantitative safety assessment of hydrogen station in Korea operating with on-site type. This was written by background information that before qualitative safety assessment to write. For the qualitative safety assessment method, the study used FMEA(failure mode & effect analysis) and HAZOP(hazard & operability), and adopted the FTA(fault tree analysis) as the quantitative safety assessment method. To write the FTA, we wrote FT by Top event that hydrogen leakage can be called most serious accident of hydrogen station. Each base event collect reliability data by reliability data handbook, THERP-HRA and estimation of the engineering. Assessment looked at the high frequency and the possible risk through Gate, Importance, m.cutsets analysis.

교량구조시스템의 유지관리를 위한 퍼지 신뢰성해석 모델 (Fuzzy Reliability Analysis Models for Maintenance of Bridge Structure Systems)

  • 김종길;손용우;이증빈;이채규;안영기
    • 한국전산구조공학회:학술대회논문집
    • /
    • 한국전산구조공학회 2003년도 가을 학술발표회 논문집
    • /
    • pp.103-114
    • /
    • 2003
  • This paper aims to propose a method that helps maintenance engineers to evaluate the damage states of bridge structure systems by using a Fuzzy Fault Tree Analysis. It may be stated that Fuzzy Fault Tree Analysis may be very useful for the systematic and rational fuzzy reliability assessment for real bridge structure systems problems because the approach is able to effectively deal with all the related bridge structural element damages in terms of the linguistic variables that incorporate systematically experts experiences and subjective judgement. This paper considers these uncertainties by providing a fuzzy reliability-based framework and shows that the identification of the optimum maintenance scenario is a straightforward process. This is achieved by using a computer program for LIFETIME. This program can consider the effects of various types of actions on the fuzzy reliability index profile of a deteriorating structures. Only the effect of maintenance interventions is considered in this study. However. any environmental or mechanical action affecting the fuzzy reliability index profile can be considered in LIFETIME. Numerical examples of deteriorating bridges are presented to illustrate the capability of the proposed approach. Further development and implementation of this approach are recommended for future research.

  • PDF