• 한국철도학회논문집
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• 제8권2호
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• pp.170-175
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• 2005

This study presents a prediction of a failure rate in a safety required system that consists of a embedded control system, requiring a satisfaction of a quantitative safety requirement. International Standards are employed to achieve a regular procedures in the whole life cycle of a system, for the purpose of a prediction and a evaluation of a fault that might be able to be happened in a system. This International Standards uses SIL (Safety Integrity Level) to evaluate a safety level of a system. SIL is divided into 4 levels, from level 1 to level 4, and each level has functional failure rate and dangerous failure rate of a system. In this paper we describe the conventional method to predict the dangerous failure rate and propose a method using hazard analysis to predict the dangerous failure rate. The conventional method and the technique using hazard analysis to predict the dangerous failure rate are made a comparison through the control modules of the interlocking system in KTX. The proposed method verify better effectiveness for the prediction of the dangerous failure rate than that of the conventional method.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2016년도 춘계학술대회
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• pp.404-406
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• 2016

해양시추시스템에 대한 국산화과정을 통해 안전성 확보가 중요한 현안으로 부각되고 있다. 이에 따라 해양시추시스템의 각 개발공정에 대한 단계별 안전성 분석 수행이 의무화되고 있다. 위험과 운전분석은 화학공장과 같은 산업에서 시스템 안전성 분석을 위해 성공적으로 사용되었던 기법이다. 이 위험과 운전분석 Study를 통해 공정에 따른 단계별 안전성 분석을 수행을 위해 해양시추시스템의 한분야인 LP Mud System에 위험과 운전분석을 수행하였다.

• 해양환경안전학회지
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• 제29권1호
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• pp.76-85
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• 2023

신재생에너지로서 수소에 대한 수요가 증가하고 있으나 기존의 화석 연료와 달리 수소는 연료 공급을 위한 전용 충전소가 필요하며, 이러한 인프라 확보를 위해서 수소충전소의 위험성 평가가 선행되어야 한다. 따라서 본 연구에서는 정성적 위험성평가와 정량적 위험성 평가로 구분하여 수소충전소에 대한 위험성평가를 수행하였다. 정성적 평가는 Hazard and Operability Analysis(HAZOP) 기법을 사용하여 Dispenser Module을 두 개의 Node로 평가하였으며, Criticality Estimation Matrix에 따라 Filter의 막힘으로 인한 사고와 고압 사고의 위험도가 High Level로 평가되었다. 정량적 위험성 평가는 Hydrogen Korea Risk Assessment Module(Hy-KoRAM)을 사용하여 화재의 형상과 피해영향범위를 나타냈고, 개인적 위험도와 사회적 위험도에 대한 평가를 수행하였다. 개인적 위험도는 수소충전소로부터 약 100m 떨어진 공공시설 부근까지 추가적인 안전조치가 고려되는 As Low As Reasonably Practicable(ALARP) 구간의 위험도를 보였고, 사회적 위험도 역시 약 10명의 사망자가 발생할 사고빈도가 1E-04/year로 도출되며 ALARP 구간 내에 나타났다. 정성적·정량적 위험성 평가 결과, 공정 단계의 추가적인 안전 조치와 수소충전소 부근의 제한구역 설정을 통하여 안전성 향상 방안을 제시하였다.

• 한국안전학회지
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• 제27권3호
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• pp.111-116
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• 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.

• 한국안전학회지
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• 제33권6호
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• pp.37-41
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• 2018

Process safety technology has developed from qualitative methods such as HAZOP (hazard and operability study) to semi-quantitative methods such as LOPA (layer of protection analysis), and quantitative methods are actively studied these days. Quantitative risk assessment (QRA) is often based on fault tree analysis (FTA). FTA is efficient, but difficult to apply when failure events are not independent of each other. This problem can be avoided using a Markov process (MP). MP requires definition of all possible states, and thus, generally, is more complicated than FTA. A method is proposed in this work that uses an MP model and a Weibull distribution model in order to construct a reliability model for multiple dependent failures. As a case study, a pressure safety valve (PSV) is considered, for which there are three kinds of failure, i.e. open failure, close failure, and gas tight failure. According to recently reported inspection results, open failure and close failure are dependent on each other. A reliability model for a PSV group is proposed in this work that is to reproduce these results. It is expected that the application of the proposed method can be expanded to QRA of various systems that have partially dependent multiple failure states.

• 한국안전학회지
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• 제35권6호
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• pp.1-8
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• 2020

In recent years, hydrogen has received much attention as an alternative energy source to fossil fuels. In order to ensure safety from the increasing number of hydrogen refueling stations, prevention methods have been required. In this regard, this study suggested an approach to reduce the risk of hydrogen refueling station by increasing Safety Integrity Level (SIL) for a Steam Methane Reformer (SMR) in On-Site Hydrogen Refueling Station. The worst scenario in the SMR was selected by HAZOP and the required SIL for the worst scenario was identified by LOPA. To verify the required SIL, the PFDavg.(1/RRF) of Safety Instrumented System (SIS) in SMR was calculated by using realistic failure rate data of SIS. Next, several conditions were tested by varying the sensor redundancy and proof test interval reduction and their effects on risk reduction factor were investigated. Consequently, an improved condition, which were the redundancy of two-out-of-three and the proof test interval of twelve months, achieved the tolerable risk resulting in the magnitude of risk reduction factor ten times greater than that of the baseline condition.

• 한국철도학회논문집
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• 제9권6호
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• pp.739-745
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• 2006

The role of maintenance in railway is going to be extended to improve the reliability of railway system in the aspect of Asset management gradually. In this paper, the meaning of reliability and safety in RCM which has been applied in order to improve the efficiency of maintenance is deduced. And the analysis task of reliability and safely which has been recommended in railway standards such as EN50126 and IEC62278 is reviewed in the aspect of RCM. Finally, the several ways are proposed to apply RCM to railway system through the comparison between the RCM procedure and the analysis procedure for the reliability and safety in railway standards. Hereafter, if the analysis of reliability and safety is performed with the concept of RCM in the beginning of railway business, it will be more efficient to improve the reliability and manage the railway asset.

• 한국가스학회지
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• 제8권4호
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• pp.70-76
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• 2004

본 연구에서는 가스 산업 시설에서의 적합한 잠재위험성 확인 기법을 선정하기 위해 가스 산업 시설 및 12가지의 기법들을 분석하고, 기법 선정에 영향을 미치는 6가지의 요소를 적용하여 기법 선정에 대한 guideline을 제시하였다. 합리적인 기법의 선정을 위해서 선정에 영향을 미치는 요소들과 각 공정 또는 설비별 사고 발생의 원인과 결과를 8가지의 특성으로 분류하여 4가지의 index를 작성하였다. 또한, flowchart 형식의 의사 결정 과정에 작성된 index를 대입하여 사용이 부적합한 기법들을 소거하고, 최적의 기법 사용에 대한 대안을 제시할 수 있도록 하였다. 또한, 규제요건 비대상 사업장의 자체적 내부 안전성 향상을 위한 guideline으로 활용될 수 있을 것이다.

• 전기학회논문지
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• 제68권1호
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• pp.199-206
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• 2019

Recently, an expansion of safety facilities has been widely applied to effectively manage the safety of train operation due to increase of the high-speed section of the general railway and the introduction of high-speed train. Accordingly, performance improvement, upgrading and high reliability of existing safety devices are required. the dragging detector, one of the safety devices, is an analogue system that consists of closed circuit with an electric current flows and operates when the closed circuit is opened by the impact of the dragging object. Such method has unreasonable problem that should be replaced after being detected. It is need to replace with an automatic return type dragging detector which is easy to maintain. In addition, it is necessary to develop a dragging detector that applicable to general railway and urban railway including high-speed railway, in accordance with the speeding up and densification of trains, although it is currently applied only to high-speed railway. In this paper, we propose an automatic return type dragging detector which has versatility and excellent maintainability with digital sensor and real time monitoring.

• 한국수소및신에너지학회논문집
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• 제33권1호
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• pp.61-66
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• 2022

In order to introduce the hydrogen economy and increase supply, research in the field of hydrogen production is being actively conducted. Among the hydrogen production methods, the method of steam reforming from natural gas and producing it currently accounts for about 50% of the global hydrogen production. In the method of steam reforming process, hydrogen can be produced by adding a reformer to an existing natural gas supply pipe. Because of these advantages, it is evaluated as a realistic production method at present in Korea, where the city gas supply chain is well established. But there is concern in that it is highly likely to be installed in downtown areas and residential spaces. In this study, the risk of the process of steam reforming to produce hydrogen was reviewed.