• Nuclear Engineering and Technology
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• 제53권1호
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• pp.103-110
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• 2021

In the development of a Risk Monitor probabilistic safety assessment (PSA) model from the basic PSA model of a nuclear power plant, the modeling of common-cause failure (CCF) is very important. At present, some approximate modeling methods are widely used, but there lacks criterion of modeling accuracy and error analysis. In this paper, aiming at ensuring the accuracy of risk assessment and minimizing the Risk Monitor PSA models size, we present three basic issues of CCF model resulted from the changes of a nuclear power plant configuration, put forward corresponding modeling methods, and derive accuracy criteria of CCF modeling based on minimum cut sets and risk indicators according to the requirements of risk monitoring. Finally, a nuclear power plant Risk Monitor PSA model is taken as an example to demonstrate the effectiveness of the proposed modeling method and accuracy criteria, and the application scope of the idea of this paper is also discussed.

• 해양환경안전학회지
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• 제21권6호
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• pp.704-711
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• 2015

본 연구에서는 침몰선박 위해도 평가항목 및 평가지수를 개정하고 신규항목을 도출하기 위해 전문가를 대상으로 AHP 기법의 설문을 실시하였다. 설문조사 결과, 사고원인 및 조류영향 등 두개의 신규항목을 도출하였으며 하나의 그룹으로 평가되었던 독성액체물질과 연료유적재량, 폭발성가스는 각각 평가하는 것이 적합한 것으로 나타났다. 이에 따라 기존 일곱 개 평가항목을 열한 개 항목으로 조정하여 평가항목별 지수를 분석한 결과, 독성액체물질, 유출가능성, 폭발성가스, 연료유적재량, 해역환경민감도, 해상교통환경, 사고원인, 조류, 여유수심, 선박종류, 선박규모 순으로 평가지수가 나타났다. 특히, 신규 도출된 평가항목 지수를 기존 위해도 평가항목과 비교해 보았을 때 해역환경민감도와 유출가능성 항목은 기존 평가지수 보다 높게 나타났고, 여유수심 항목의 평가지수는 더 낮게 나타났다.

• Journal of Preventive Medicine and Public Health
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• 제47권1호
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• pp.27-35
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• 2014

Exposure factors based on the Korean population are required for making appropriate risk assessment. It is expected that handbooks for exposure factors will be applied in many fields, as well as by health department risk assessors. The present article describes the development of an exposure factors handbook that specifically focuses on human activities in situations involving the possible risk of exposure to environmental contaminants. We define majour exposure factors that represent behavioral patterns for risk assessment, including time spent on routine activities, in different places, on using transportation, and engaged in activities related to water contact including swimming, bathing and washing. Duration of residence and employment are also defined. National survey data were used to identify recommended levels of exposure factors in terms of time spent on routine activities and period of residence and employment. An online survey was conducted with 2073 subjects who were selected using a stratified random sampling method in order to develop a list of exposure factors for the time spent in different places and in performing water-related activities. We provide the statistical distribution of the variables, and report reference levels of average exposure based on the reliable data in our exposure factors handbook.

• Earthquakes and Structures
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• 제14권3호
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• pp.249-259
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• 2018

This paper aims to assess the seismic risk of a plane moment-resisting frames (MRFs) consisting of concrete-filled double skin steel tube (CFDST) columns and I-section steel beams. Firstly, three typical limit performance levels of CFDST structures are determined in accordance with the cyclic tests of seven CFDST joint specimens with 1/2-scaled and the limits stipulated in FEMA 356. Then, finite element (FE) models of the test specimens are built by considering with material degradation, nonlinear behavior of beam-column connections and panel zones. The mechanical behavior of the concrete material are modeled in compression stressed condition in trip-direction based on unified strength theory, and such numerical model were verified by tests. Besides, numerical models on 3, 6 and 9-story CFDST frames are established. Furthermore, the seismic responses of these models to earthquake excitations are investigated using nonlinear time-history analyses (NTHA), and the limits capacities are determined from incremental dynamic analyses (IDA). In addition, fragility curves are developed for these models associated with 10%/50yr and 2%/50yr events as defined in SAC project for the region on Los Angeles in the Unite State. Lastly, the annual probabilities of each limits and the collapse probabilities in 50 years for these models are calculated and compared. Such results provide risk information for the CFDST-MRFs based on the probabilistic risk assessment method.

• 한국산업보건학회지
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• 제25권2호
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• pp.146-155
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• 2015

Objectives: The aims of this study were to set up benzene exposure matrices according to industry and process and to assess the risk of those occupational exposure to benzene. Methods: The benzene exposure matrices were assembled depending on industry and process, based on an exposure database provided by KOSHA(the Korean Occupational Safety and Health Agency), which was gathered from a workplace hazards evaluation program in Korea. These exposure matrices were assessed by Hallmark Risk Assessment tool. Results: The benzene was treated 412 industries sector(36%), 2,747 business places, and 471 industrial processes according to database. The arithmetic mean of past decade 8 hours time-weighted average of airborne benzene concentrations in the workplace was 0.10722 ppm. 1.07% of the total sample were greater than OEL, and 59.8% were showed less than the limit of detection. The highest risk values(Danger Value) were seen 36 industries including manufacture of general paints and similar product and 12 processes, such as other painting of manufacture of metal fabricated members. Exposure matrices based on employee exposure data base may provide exposure histories and can be used in epidemiological studies. Conclusions: It was found that more attentions should be paid to 36 among 412 industries and 12 of 471 processes, with a higher risk value.

• Ocean Systems Engineering
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• 제9권3호
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• pp.261-285
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• 2019

Nowadays in offshore industry there are emerging hazards with vague property such as act of terrorism, act of war, unforeseen natural disasters such as tsunami, etc. Therefore industry professionals such as offshore energy insurers, safety engineers and risk managers in order to determine the failure rates and frequencies for the potential hazards where there is no data available, they need to use an appropriate method to overcome this difficulty. Furthermore in conventional risk based analysis models such as when using a fault tree analysis, hazards with vague properties are normally waived and ignored. In other word in previous situations only a traditional probability based fault tree analysis could be implemented. To overcome this shortcoming fuzzy set theory is applied to fault tree analysis to combine the known and unknown data in which the pre-combined result will be determined under a fuzzy environment. This has been fulfilled by integration of a generic bow-tie based risk analysis model into the risk assessment phase of the Risk Management (RM) cycles as a backbone of the phase. For this reason Fault Tree Analysis (FTA) and Event Tree Analysis (ETA) are used to analyse one of the significant risk factors associated in offshore terminals. This process will eventually help the insurers and risk managers in marine and offshore industries to investigate the potential hazards more in detail if there is vagueness. For this purpose a case study of offshore terminal while coinciding with the nature of the Caspian Sea was decided to be examined.

• 수산해양기술연구
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• 제50권4호
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• pp.567-582
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• 2014

Coastal fisheries in Korean waters have highly complexity with a variety of fishing gears, and scale of those fisheries is smaller than that of offshore fisheries. As a result, important spawning and nursery grounds for many species of fish has been destroyed. The pragmatic ecosystem-based approach was developed for the assessment of fisheries resources in Korean waters by Zhang et al. (2009; 2010). As for the species risk index (SRI), common squid caught by coastal gillnet in the Uljin region had the highest risk. As for the fisheries risk index (FRI), coastal gillnet in the Uljin coastal waters had the highest risk. For the common squid which had the highest SRI, resources management strategies must be established such as catch prohibition of length and period with TAC. For the coastal gillnet in the Uljin region which had the highest FRI, it is judged to need management plans for conserving biodiversity as reducing the catch of non-target species and discards. Also to protect existing habitat, illegal fishery should be prohibited, and fishing gears should be designed in the environmental-friendly way considering when fishing gears lost.

• Toxicological Research
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• 제28권2호
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• pp.129-137
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• 2012

Probabilistic ecological risk assessment (PERA) for deriving ecological protective concentration (EPC) was previously suggested in USA, Australia, New Zealand, Canada, and Netherland. This study suggested the EPC of cadmium (Cd) based on the PERA to be suitable to Korean aquatic ecosystem. First, we collected reliable ecotoxicity data from reliable data without restriction and reliable data with restrictions. Next, we sorted the ecotoxicity data based on the site-specific locations, exposure duration, and water hardness. To correct toxicity by the water hardness, EU's hardness corrected algorithm was used with slope factor 0.89 and a benchmark of water hardness 100. EPC was calculated according to statistical extrapolation method (SEM), statistical extrapolation $method_{Acute\;to\;chronic\;ratio}$ ($SEM_{ACR}$), and assessment factor method (AFM). As a result, aquatic toxicity data of Cd were collected from 43 acute toxicity data (4 Actinopterygill, 29 Branchiopoda, 1 Polychaeta, 2 Bryozoa, 6 Chlorophyceae, 1 Chanophyceae) and 40 chronic toxicity data (2 Actinopterygill, 23 Branchiopoda, 9 Chlorophyceae, 6 Macrophytes). Because toxicity data of Cd belongs to 4 classes in taxonomical classification, acute and chronic EPC (11.07 ${\mu}g/l$ and 0.034 ${\mu}g/l$, respectively) was calculated according to SEM technique. These values were included in the range of international EPCs. This study would be useful to establish the ecological standard for the protection of aquatic ecosystem in Korea.

• 한국가스학회지
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• 제17권4호
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• pp.39-44
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• 2013

최근 화학공장에서는 대형 폭발사고 등이 주로 유지 보수의 정비 시에 많이 발생되고 있다. 정비 시에 효과적인 재해예방을 하기 위해서는 핵심대상을 찾는 것이 매우 필요하다. 이 논문에서는 재해예방의 핵심요인을 찾기 위해 핵심대상으로 화학설비를 선정하였고, 화학설비별로 위험순위도를 정하여 재해예방의 대책을 세우는 우선순위를 밝히고자 하였다. 연구방법으로 화학설비의 종류는 재해분석을 통하여 찾고, 화학설비별 위험도는 재해분석을 통해 가능성인 재해빈도와 중대성인 재해강도의 근로손실일 수를 기준하여 산정하였다. 또한 화학설비별로 전문가들의 지식과 경험을 바탕으로 한 지식기반 기법에 의한 가능성과 중대성 자료를 활용하여 위험도를 산정하였다. 연구결과, 화학공장의 정비 시에 재해예방을 위해 화학설비별 위험순위는 반응기, 건조기, 탱크로리 등의 순위로 나타났다. 이 결과로부터 화학공장의 정비 시에 재해예방을 위해 위험순위에 따른 각별한 대책과 주의를 기울여야 할 것으로 사료된다.

• 한국수소및신에너지학회논문집
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• 제33권1호
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• pp.55-60
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• 2022

As interest in sustainable and eco-friendly energy sources is increasing due to various problems in the carbon society, a hydrogen economy using hydrogen as a main energy source is emerging. While the natural gas reforming method generates carbon dioxide, the water electrolysis method based on renewable energy is eco-friendly. The water electrolysis device currently being developed uses a 2 Nm³/hr class alkaline aqueous solution as an electrolyte and produces hydrogen based on renewable energy. In this study, risk assessment was conducted for these water electrolysis devices