• 대한조선학회논문집
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• 제49권6호
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• pp.447-460
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• 2012

In this study, the shutdown system of the fuel gas supply system is designed based on the Safety Integrity Level of IEC 61508 and IEC 61511. First of all, the individual risk($10^{-4}$/year) and the risk matrix which are the risk acceptance criteria are set up for the qualitative risk assessment such as the HAZOP study. The natural gas leakage at the gas supply pipe is identified as the highest risk among the hazards identified through the HAZOP study and as a safety instrumented function the shutdown function for leakage was defined. SIL 2 and PFD($2.5{\cdot}10^{-3}$) for the shutdown function are determined by the layer of protection analysis(LOPA). The shutdown system(SIS) carrying out the shutdown function(SIF) is verified and designed according to qualitative and quantitative requirements of IEC 61508 and IEC 61511. As a result of SIL verification and SIS conceptual design, the shutdown system is composed of two gas detectors voted 1oo2, one programmable logic solver, and two shutdown valve voted 1oo2.

• 한국화재소방학회논문지
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• 제20권3호
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• pp.1-8
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• 2006

본 논문의 목적은 Ethyl Benzene 플랜트의 공정에서 과압 현상이 Column 상부의 반응폭주 및 화재 폭발의 원인이 되기 때문에 안전장치시스템의 신뢰도가 압력방출밸브가 요구하는 안전건전성수준으로 설계되어 있는지를 정량적으로 분석한 것이다. 압력방출밸브의 요구시 실패확률은 일반신뢰도 자료 조사결과를 근거로 하여 안전장치시스템에 대한 안전건전성수준의 목표등급을 SIL3으로 설정하였고, 이에 대한 PFD를 1.00E-3에서 1.00E-4로 결정하였다. 신뢰도 모델의 구축 및 결함수 분석기법을 이용하여 SIS의 요구시 실패확률에 대한 정량화를 수행한 결과 SIS에 대한 PFD는 Benzene Prefractionator Column, Benzene Column, EB Column에 대해 각각 8.97E-04, 5.37E-04, 5.37E-04로 계산되었다. 따라서 SIS의 신뢰도가 SIL3 등급에 요구되는 안전건전성수준으로 설계되어 있다고 판단되며 컨트롤밸브에 대한 6개월 주기의 Partial Stroke Test가 수행될 경우 각 Column의 SIS는 약 $22{\sim}27%$의 신뢰도 향상이 기대된다.

• 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.

• 대한조선학회논문집
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• 제49권3호
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• pp.239-246
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• 2012

It is the well-known fact that most part of goods transported are moved on the unfavorable ocean and even a small amount of accident on sea is extremely dangerous for human lives, financial losses, and social responsibility. Among the several causes of accidents, those by fire have occurred frequently and their damage has been highly serious. The aim of this paper is to assess the risk of fires due to oil leakage in the machinery space. To define the possible fire scenario, our team has performed the search of casualty database and reviewed the previous and various studies in the field. As a result, it is noted that the quantitative risk of the fire scenario have been evaluated on the ground of the FSA risk model. The expected frequency of a fire amounts to incidents during the life of a ship, and the expected financial damage amounts to 5,654 USD per a ship. By adopting Safety Instrumented System (SIS) introduced in IEC 61508 and IEC 61511, SIS model is designed to prevent oil leakage fire as a risk reduction method. It is concluded that System Integrity Level (SIL) 1 seems to be appropriate level of SIS.

• 전기학회논문지P
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• 제66권1호
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• pp.43-47
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• 2017

A SIL(Safety Integrity Level) assignment method is used for preventing failure action. The goal of safety system for processing automation is to reduce the human fatal risk. Even if we have developed the processing automation according to developing technology, we are also realized on increasing the human fatal risk cause of unexpected accidents. This study is directed the solution of decision for safety level for safety system and the best architecture for safety system in process automation.

• 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.

• 한국가스학회지
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• 제6권1호
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• pp.66-73
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• 2002

본 연구에서는 결함수목 분석법을 이용하여 Safety Integrity Level(SIL)을 평가하고 시스템의 목표한 SIL에 도달하지 못할 경우에 신뢰도 분석과 시스템 retrofit을 통해서 목표한 SIL을 만족시키게 하는 방법을 개발하였다. 신뢰도 분석에 근거한 SIL 평가 방법을 검증하기 위해서 415V Diesel BUS에 대해서 위험성 분석을 수행하였다. 기존의 415V Diesel BUS에 대한 이용가능 상태는 $99.40\%$로 SIL 2등급에 해당된다. 개발된 평가방법을 이용하여 diesel generator와 isolator switch의 교체후 시스템의 이용가능 상태는 $99.94\%$ SIL 3등급으로 상승되었다. 본 연구에서 제시한 신뢰도에 근거한 SIL 평가 방법을 적용하면 사고 예방과 손실감소로 일어나는 유지보수 비용의 절감 등을 가져오면 물론 시스템의 신뢰도를 극대화 할 수 있다.

• 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.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.1
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• pp.235-240
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• 2006

The paper will give an overview of the mission of GalTeC and then concentrate on two main aspects. The first more detailed aspect, is the analysis of the key performance parameters for the Galileo system services and presenting a technical overview of methods and algorithms used. The second more detailed aspect, is the service volume prediction including service dimensioning using the Prediction tool. In order to monitor and validate the Galileo SIS performance for Open Service (OS) and Safety Of Life services (SOL) regarding the key performance parameters, different analyses in the SIS domain and User domain are considered. In the SIS domain, the validation of Signal-in-Space Accuracy SISA and Signal-in-Space Monitoring Accuracy SISMA is performed. For this purpose first of all an independent OD&TS and Integrity determination and processing software is developed to generate the key reference performance parameters named as SISRE (Signal In Space Reference Errors) and related over-bounding statistical information SISRA (Signal In Space Reference Accuracy) based on raw measurements from independent sites (e.g. IGS), Galileo Ground Sensor Stations (GSS) or an own regional monitoring network. Secondly, the differences of orbits and satellite clock corrections between Galileo broadcast ephemeris and the precise reference ephemeris generated by GalTeC will also be compared to check the SIS accuracy. Thirdly, in the user domain, SIS based navigation solution PVT on reference sites using Galileo broadcast ephemeris and the precise ephemeris generated by GalTeC are also used to check key performance parameters. In order to demonstrate the GalTeC performance and the methods mentioned above, the paper presents an initial test result using GPS raw data and GPS broadcast ephemeris. In the tests, some Galileo typical performance parameters are used for GPS system. For example, the maximum URA for one day for one GPS satellite from GPS broadcast ephemeris is used as substitution of SISA to check GPS ephemeris accuracy. Using GalTeC OD&TS and GPS raw data from IGS reference sites, a 10 cm-level of precise orbit determination can be reached. Based on these precise GPS orbits from GalTeC, monitoring and validation of GPS performance can be achieved with a high confidence level. It can be concluded that one of the GalTeC missions is to provide the capability to assess Galileo and general GNSS performance and prediction methods based on a regional and global monitoring networks. Some capability, of which first results are shown in the paper, will be demonstrated further during the planned Galileo IOV phase, the Full Galileo constellation phase and for the different services particularly the Open Services and the Safety Of Life services based on the Galileo Integrity concept.

• International Journal of Naval Architecture and Ocean Engineering
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• 제8권3호
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• pp.262-276
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• 2016

Generally, the Safety Integrity Level (SIL) of a subsea Blowout Preventer (BOP) is evaluated by determining the Probability of Failure on Demand (PFD), a low demand mode evaluation indicator. However, some SIL results are above the PFD's effective area despite the subsea BOP's demand rate being within the PFD's effective range. Determining a Hazardous Event Frequency (HEF) that can cover all demand rates could be useful when establishing the effective BOP SIL. This study focused on subsea BOP functions that follow guideline 070 of the Norwegian Oil and Gas. Events that control subsea well kicks are defined. The HEF of each BOP function is analyzed and compared with the PFD by investigating the frequency for each event and the demand rate for the components. In addition, risk control options related to PFD and HEF improvements are compared, and the effectiveness of HEF as a SIL verification for subsea BOP is assessed.