• 한국안전학회지
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• 제31권4호
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• pp.156-163
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• 2016

There exists required safety integrity level (SIL) to assure safety in accordance with international standards for every electrical / electronics / control equipment or systems with safety related functions. The SIL is allocated from lowest level (level 0) to highest level (level 4). In order to guarantee certain safety level that is internationally acceptable, application of methodology for SIL allocation and demonstration based on related international standards is required. However, the theoretical and practical study for safety integrity level is barely under way in the domestic railway industry. This research studied not only the global process of SIL allocation to guarantee safety in accordance with international standards for safety related equipment and system, but the quantitative methodology based on international standard and the semi-quantitative methodology as alternative way for SIL allocation. Specifically, the systematic SIL allocation for platform screen door system of railway is studied applying the semi-quantitative methodology in order to save much time and effort compared to quantitative method.

• 한국안전학회지
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• 제30권6호
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• pp.164-173
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• 2015

There exists required safety integrity level (SIL) to assure safety in accordance with international standards for every electrical / electronics / control equipment or systems with safety related functions. The SIL is allocated from lowest level (level 0) to highest level (level 4). In order to guarantee certain safety level that is internationally acceptable, application of methodology for SIL allocation and demonstration based on related international standards is required. However, application standard differs from every industry in domestic or international for application on mythology for allocation and demonstration of SIL. Application or assessment is not easy since absence on clear criteria or common definition. This research studied not only fundamental concept of SIL required to guarantee safety in accordance with international standards for safety related equipment and system, but different types of methodologies for SIL allocation. Specifically, SIL allocation for Platform Screen Door system of railway is studied applying methodology of severity of accidents and risk graph among different methodologies for SIL allocation.

• 한국안전학회지
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• 제31권5호
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• pp.141-148
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• 2016

There exists required safety integrity level (SIL) to assure safety in accordance with international standards for every electrical / electronics / control equipment or systems with safety related functions. The SIL is allocated from lowest level (level 0) to highest level (level 4). In order to guarantee certain safety level that is internationally acceptable, application of methodology for SIL allocation and demonstration based on related international standards is required. Especially, in case of the SIL allocation method without determining of quantitative tolerable risk, the additional review is needed to check whether it is suitable or not is required. In this study, the quantitative risk reduction model based on the safety integrity allocation results of railway platform screen door system using Risk Graph method has been examined in order to review the suitability of quantitative risk reduction according to allocated safety integrity level.

• 한국안전학회지
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• 제27권5호
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• pp.64-69
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• 2012

The concept of SIL is applied in the most of all standards relating to functional system safety. However there are problems for the people to apply SIL to their plants. as these standards don't include sufficient informations. In this regards, this paper will suggest the direction of SIL application and concept based on IEC 61508 and IEC 61511. A Safety Integrity Level(SIL) is the discrete level(one out of possible fours), corresponding to a range of the probability of an E/E/PE (Electric/Electrical/Programmable Electrical) safety-related system satisfactorily performing the specific safety functions under all the stated conditions within a stated period of time. SIL can be divided into the target SIL(or required SIL) and the result SIL. The target SIL is determined by the risk analysis at the analysis phase of safety lifecycle and the result SIL is calculated during SIL verification at the realization phase of safety lifecycle. The target SIL is determined by the risk analysis like LOPA(Layer Of Protection Analysis), Risk Graph, Risk Matrix and the result SIL is calculated by HFT(Hardware Fault Tolerance), SFF(Safe Failure Fraction) and PFDavg(average Probability of dangerous Failure on Demand). SIL is applied to various areas such as process safety, machinery(road vehicles, railway application, rotating equipment, etc), nuclear sector which functional safety is applied. The functional safety is the part of the overall safety relating to the EUC and the EUC control system that depends on the correct functioning of the E/E/PE safety-related systems and other risk reduction measures. SIL is applied only to the functional safety of SIS(Safety Instrumented System) in safety. EUC is the abbreviation of Equipment Under Control and is the equipment, machinery, apparatus or plant used for manufacturing, process, transportation, medical or other activities.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권12호
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• pp.6079-6097
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• 2018

Safety-related systems (SRSs) has widely used in shipbuilding and power generation to prevent fatal accidents and to protect life and property. Thus, SRS performance is a high priority. The safety integrity level (SIL) is the relative performance level of an SRS with regard to its ability to operate reliably in a safe manner. In this article, we proposed an optimal design procedure to achieve the targeted SIL of SRSs. In addition, a more efficient failure mode and effects diagnostic analysis (FMEDA) process and optimization model were developed to improve cost efficiency. Based on previous IEC 61508 diagnostic analyses that revealed unnecessary costs associated with excessive reliability, the new approach consists of two phases: (i) SIL evaluation by FMEDA, and (ii) solution optimization for achieving the target SIL with minimal cost using integer-programming models. The proposed procedure meets the required safety level and minimizes system costs. A case study involving a gas-detection SRS was conducted to demonstrate the effectiveness of the new procedure.

• 한국신뢰성학회지:신뢰성응용연구
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• 제10권2호
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• pp.107-122
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• 2010

Functional safety is the part of the overall safety of a system that depends on the system or equipment operating correctly in response to its inputs, including the safe management of likely operator errors, hardware failures, systematic failures, and environmental changes. One of the essential concepts of functional safety is Safety Integrity Level(SIL). It is defined as a relative level of risk-reduction provided by a safety function, or to specify a target level of risk reduction. In this paper, each element of SIL assessment will be defined. Based on each element, specific process of SIL selection will be established by using flowchart. The flowchart provides a SIL assessment guideline for functional safety engineers. The proposed theory will be verified by applying to a oil refining plant for SIL assessment.

• 한국신뢰성학회지:신뢰성응용연구
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• 제14권1호
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• pp.81-91
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• 2014

The IEC 61508 standard was established to specify the functional safety of E/E/PE safety-related systems. Safety life cycle to provide the framework and direction for the application of IEC 61508 is included in this standard. In this paper, we describe overviews, objects, scopes, requirements and activities of each phase in safety life cycle. In addition, we introduce safety integrity level(SIL) which is used for verifying the safety integrity requirements of E/E/PE system and perform a case study to estimate hardware SIL by FMEDA. The SIL is evaluated by two criteria. One of them is the architectural constraints which restrict the maximum SIL by combination of SFF and HFT. The other is the probability of failure which is classified into PFD and PFH based on frequency of demand and calculated by safe or dangerous failure rates.

• 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.

• 한국가스학회지
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• 제15권5호
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• pp.57-62
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• 2011

현대의 화학공장 및 석유 가스산업 시설은 공정 및 설비가 더욱 복잡해지고 세분화됨으로써 산업현장에서는 다양한 잠재위험으로 인하여 화재, 폭발, 독성물질 누출 등의 중대 산업사고의 발생 가능성 및 사고결과의 피해가능 범위가 증가되고 있다. 이러한 위험요소를 줄이기 위하여 공정 내 안전장치를 설치하여 공정의 위험도를 줄여야 하지만, 공장 운전 효율성과 안전도는 서로 적절한 수준을 유지하지 않으면 잦은 검사와 확인으로 효율성을 저해할 수 있다. 그를 위하여 이번 연구에서 SIL(Safety Integrity Level)을 이용한 SIF(Safety Instrument Function)의 추가로 장치의 적절한 사양, 설계를 이루고 공정내의 잠재위험이 사고로 이어지는 것을 방지하여, 화학공장의 안전성을 향상시켰다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.838-849
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• 2010

It is inevitable to control the systematic failure to obtain the software safety integrity of embedded software installed in rolling stock. Because it is not possible to assess systematic failure integrity by quantitative methods, SILs are used to group documentation, methods, tools and techniques throughout software development lifecycle which, when used effectively, are considered to provide an appropriate level of confidence in the realization of a system to a stated integrity level. Normally, safety approval process is through generic product, generic application and specification application for. For safety approval on generic application of software based system, it is required to apply the certified software processes from the planning stage for the assigned SIL. As such, we will develop project specific application with high safety integrity within time limit of contractual delivery schedule through software assessment to the modified area with the re-use of certified software module and documentation. At this point, Hyundai Rotem has developed software processes applicable to support SIL 4 based on EN50128 which was assessed and certified by TUV SUD. This paper introduces the Hyundai Rotem's detailed approach and prospective action to achieve software safety integrity level.