• Nuclear Engineering and Technology
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• 제50권8호
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• pp.1234-1245
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• 2018

The risk of multi-unit nuclear power plants (NPPs) at a site has received considerable critical attention recently. However, current probabilistic safety assessment (PSA) procedures and computer code do not support multi-unit PSA because the traditional PSA structure is mostly used for the quantification of single-unit NPP risk. In this study, the main purpose is to develop a multi-unit Level 2 PSA method and apply it to full-power operating six-unit OPR1000. Multi-unit Level 2 PSA method consists of three steps: (1) development of single-unit Level 2 PSA; (2) extracting the mapping data from plant damage state to source term category; and (3) combining multi-unit Level 1 PSA results and mapping fractions. By applying developed multi-unit Level 2 PSA method into six-unit OPR1000, site containment failure probabilities in case of loss of ultimate heat sink, loss of off-site power, tsunami, and seismic event were quantified.

• Nuclear Engineering and Technology
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• 제44권7호
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• pp.745-754
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• 2012

The correlations between Large Early Release Frequency (LERF) and Early Fatality need to be investigated for risk-informed application and regulation. In Regulatory Guide (RG) -1.174, while there are decision-making criteria using the measures of Core Damage Frequency (CDF) and LERF, there are no specific criteria on LERF. Since there are both huge uncertainties and large costs needed in off-site consequence calculation, a LERF assessment methodology needs to be developed, and its correlation factor needs to be identified, for risk-informed decision-making. A new method for estimating off-site consequence has been presented and performed for assessing health effects caused by radioisotopes released from severe accidents of nuclear power plants in this study. The MACCS2 code is used for validating the source term quantitatively regarding health effects, depending on the release characteristics of radioisotopes during severe accidents. This study developed a method for identifying correlations between LERF and Early Fatality and validates the results of the model using the MACCS2 code. The results of this study may contribute to defining LERF and finding a measure for risk-informed regulations and risk-informed decision-making.

• 중환자간호학회지
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• 제15권3호
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• pp.75-87
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• 2022

Purpose : This retrospective investigation study aimed to determine the predictive validity of superficial surgical site infection assessment tools by measuring the risk score at the surgical site. Methods : This study included patients hospitalized to the general surgery department of a Hospital from January 2021 to December 31, 2021. The inclusion criteria were age ≥19 years, general abdominal surgery under general anesthesia, and hospital stay longer than 2 days. Patients who had undergone transplantation were excluded. Results : Tool validity results showed that tools including surgical time and operative procedure were more accurate than previously developed tools, with a sensitivity of 71.1%, specificity of 71.4%, positive prediction of 12.3%, negative prediction of 97.8%, and area under the curve of 0.743 (95% confidence interval, 0.678~0.745). The tool's cut-off score was 15, and the risks of infection was increased by 6.14 times at or above this cut-off point. Preoperative hair removal period, surgical wound classification, surgery time, body temperature on the second day after surgery, drainage tube type, and suture type affected the risk of infection at the surgical site. Conclusion : The incidence of healthcare-associated infections has been declining in the past decade; however, surgical site infections still account for a considerable proportion. Therefore, early identification of high-risk groups for surgical site infection is crucial for reducing the incidence of surgical site infection using appropriate management.

• 대한안전경영과학회지
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• 제19권4호
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• pp.133-140
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• 2017

The Ministry of Science, ICT and Future Planning made law for Pre-Hazard Risk Analysis in December 31, 2014 to protect researchers from continuing accidents in laboratory. Conducted before an experiment, Pre-Hazard Risk Analysis finds hazards of the experiment and rules to manage the hazards.So the Pre-Hazard Risk Analysis can support laboratory safety system by prevent accidents in laboratory. Pre-Hazards Risk Analysis is newly created system so that executors need Guidelines to perform this analysis properly. This study is to develop guide tool for Pre-Hazard Risk Analysis by analyzing other risk assessment systems; PSM, Off-site Consequence Assessment, laboratory safety system. Also, this study suggested how to establish database for Pre-Hazard Risk Assessment by analyse KRAS.

• 한국가스학회지
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• 제22권3호
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• pp.38-44
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• 2018

암모니아는 발전소의 탈질설비, 냉동장치의 냉매로 많이 사용되고 있으며, 증기압이 높고 공기보다 가벼운 물질로써 장외영향평가시 영향범위가 넓은 물질이다. KORA(Korea Off-site Risk Assessment supporting tool)를 활용하여 4가지 환경인자인 지면굴곡도, 밀폐여부, 운전온도 압력, 누출공 크기를 달리하여 영향범위를 산출하였다. 그 결과 굴곡도에 따른 영향범위는 약 4.62배 차이가 났으며 암모니아 저장탱크는 밀폐된 경우가 약 0.64의 저감율을 나타냈다. 저장온도와 압력에 따라 누출률이 증가되어 영향범위도 증가하는 형태를 보였으며 포화증기압 이상으로 저장시 영향범위는 $45^{\circ}C$에서 0.1 Mpa 당 평균 3.45%의 증가율을 나타냈다. 누출공 크기에 따른 영향범위 산정 결과는 누출구의 면적에 비례하는 것으로 나타났다.

• 한국가스학회지
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• 제21권3호
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• pp.9-16
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• 2017

위험물을 취급하는 사업장에서 인근에 미치는 영향을 평가할 때 독성물질의 누출은 가장 관심있는 분야중의 하나이다. 대표적인 시설로서 염산 생산시설을 선정하여 공정정보로부터 사고 시나리오를 선정하고 독성물질 누출시 사업장외로 영향을 미치는 사고 시나리오를 선정하여 환경부의 지침에 따라서 평가하였다. ALOHA를 활용하여서 최악의 사고 시나리오를 비롯한 사고 시나리오를 평가하였으며 이들의 사고시 피해완화대책도 살펴보았다. 평가결과 염산생산시설은 현재의 안전조치가 충분하여서 추가의 개선대책이 필요하지 않은 것으로 판명되었다.

• Korean Chemical Engineering Research
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• 제54권6호
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• pp.781-785
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• 2016

위험물인 염산을 취급하는 사업장에서 발생할 수 있는 사고를 알아내고 사고시 인근에 미치는 영향을 평가하여 어느 정도 위험이 있는지 알아보며 이에 대한 대비책을 적용하고자 하였다. 취급 화학물질 정보와 공정정보로부터 사고 시나리오를 선정하고 염산 누출시 사업장외로 영향을 미치는 사고 시나리오를 선정하여 환경부의 지침에 따라서 ALOHA를 활용하여서 평가하였다. 최악의 사고 시나리오를 비롯한 사고 시나리오를 평가하였으며 이들의 사고시 피해완화대책도 살펴보았다. 평가결과 염산생산시설은 현재의 안전조치가 충분하여서 추가의 개선대책이 필요하지 않은 것으로 판명되었다.

• 한국화재소방학회논문지
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• 제32권3호
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• pp.76-87
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• 2018

본 연구는 화학공장에서 원료 및 중간재로 많이 사용되는 Heavy Gas인 염소를 화학설비의 가압 염소포화액체 저장탱크에서 2상 흐름 연속누출에 대한 유해위험거리를 정량적으로 예측하기 위한 피해영향 모델링이다. 피해예측을 위한 평가방법과 사고영향평가모델들을 기준으로 액체염소 저장용기의 누출사고에서 사고결과에 미치는 최적의 변수를 나타나기 위해 조업조건을 표준조건으로 하였다. 장외영향평가의 위험성 평가에 사용되는 것으로 USEPA와 NOAA에서 공동 개발된 대기확산 모델인 ALOHA (V5.4.4) 모델을 사용하였다. 화학물질을 대량으로 제조 및 취급하고 있는 여수 국가산업단지를 연구 대상지역으로하여, 기상변수와 공정변수들을 설정하여 시나리오별로 모델링을 하여 누출사고에 대한 특성을 도출하였다. 가우시안 확산모델에 따른 관심지점의 농도 추정치를 산출하였고, ALOHA 모델링 결과 염소 확산에 의한 유해위험거리는 대기온도가 높고 풍속의 감소와 대기 안정도가 안정할수록 증가 하는 것으로 분석되었다.

• 한국안전학회지
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• 제31권4호
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• pp.126-135
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• 2016

The purpose of this study is to develop risk assessment techniques and institutional analysis of domestic and international, the management techniques that can efficiently manage the harmful factor of the laboratory and to present the institutional measures that can be efficiently implemented. Due to a variety of adverse factors of laboratory, accidents of laboratory of various forms have occurred, but there is no risk assessment system in order to manage this effectively. So, we investigated this domestic existing risk assessment methods and the outside of the risk assessment system, and also analyzed accidents of domestic laboratory that occurred in 2014. In addition, we targeted the 24 laboratories in 21 universities to investigate the management of harmful factors of the laboratory and performed applying test for 12 domestic laboratories. Existing risk evaluation system, such as PMS, SMS, off-site impact assessment, since the industrial site is the subject, is a difficult problem to be directly applied to the laboratory of the research institute. So, we implemented management status and harmful factors survey and classified the research and development activities based on this data. Finally we developed "pre-hazards risk analysis method" to create each of the safety management measures. In addition, research activities personnel conducted voluntarily risk assessment, which is shared by institutions and government. It is presented the institutional system for safety management of laboratory. Its result, pre-hazards risk analysis method and institutionalization scheme will be able to achieve laboratory accident prevention system.

• Nuclear Engineering and Technology
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• 제50권8호
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• pp.1246-1254
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• 2018

The importance of performing Level 3 probabilistic safety assessments (PSA) along with a general interest in assessing multi-unit risk has been sharply increasing after the Fukushima Daiichi nuclear power plant (NPP) accident. However, relatively few studies on multi-unit Level 3 PSA have been performed to date, reflecting limited scenarios of multi-unit accidents with higher priority. The major difficulty to carry out a multi-unit Level 3 PSA lies in the exponentially increasing number of multi-unit accident combinations, as different source terms can be released from each NPP unit; indeed, building consequence models for the astronomical number of accident scenarios is simply impractical. In this study, a new approach has been developed that employs the look-up table method to cover every multi-unit accident scenario. Consequence results for each scenario can be found on the table, established with a practical amount of effort, and can be matched to the frequency of the scenario. Preliminary application to a six-unit NPP site was carried out, where it was found that the difference between full-coverage and cut-off cases could be considerably high and therefore influence the total risk. Additional studies should be performed to fine tune the details and overcome the limitations of the approach.