• Nuclear Engineering and Technology
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• 제56권6호
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• pp.2079-2091
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• 2024

In this paper, a model is developed for calculating pH in the presence of organic impurities due to dissolution of paint and/or continuous injection of organic impurities in the sump. The model is implemented in the AnCheBi code for the analysis of chemical behaviors of the iodine in the containment when the pH changes during a severe accident. Validation of the model is performed with P10T2 and P11T1 experiments carried out by AECL in Canada under the BIP project. Importance analyses of the pH calculation model in the AnCheBi code are then performed with the aforementioned experimental data via Latin hypercube sampling on the reaction coefficients, sensitivity analyses of AnCheBi, and calculation of the correlation coefficients between the reaction coefficients and figure of merits (the pH and the concentrations of the various iodine species). From the importance analyses, we provide the sensitivity of the pH calculation model to the change of pH and the concentrations of the various iodine species and the reaction coefficients related with the dominant phenomena underlying the change of pH and the concentrations of the species.

• Safety and Health at Work
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• 제12권1호
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• pp.42-50
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• 2021

Introduction: Despite huge investments in new technology and transportation infrastructure, terrible accidents still remain a reality of traffic. Methods: Severe traffic accidents were analyzed from four prevailing modes of today's transportations: sea, air, railway, and road. Main root causes of all four accidents were defined with implementation of the approach, based on Flanagan's critical incident technique. In accordance with Molan's Availability Humanization model (AH model), possible preventive or humanization interventions were defined with the focus on technology, environment, organization, and human factors. Results: According to our analyses, there are significant similarities between accidents. Root causes of accidents, human behavioral patterns, and possible humanization measures were presented with rooted graphs. It is possible to create a generalized model graph, which is similar to rooted graphs, for identification of possible humanization measures, intended to prevent similar accidents in the future. Majority of proposed humanization interventions are focused on organization. Organizational interventions are effective in assurance of adequate and safe behavior. Conclusions: Formalization of root cause analysis with rooted graphs in a model offers possibility for implementation of presented methods in analysis of particular events. Implementation of proposed humanization measures in a particular analyzed situation is the basis for creation of safety culture.

• 대한교통학회지
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• 제29권6호
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• pp.67-74
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• 2011

이 연구는 차량유형별 로터리 교통사고를 다루고 있다. 이 논문은 차량유형별 교통사고 특성을 비교 분석하고, 사고모형을 개발하는데 그 목적이 있다. 이를 위해 이 연구에서는 차량유형을 세 그룹으로 나누어 그 차이점을 분석하고, 국내 로터리 자료를 이용하여 포아송 및 음이항 회귀모형과 ZAM모형을 개발하는데 중점을 두고 있다. 주요 연구결과는 다음과 같다. 첫째, 승용차량과 화물 및 승합차, 원동기의 사고건수를 종속변수로 하는 통계적으로 의미있는 2개의 ZIP 모형과 1개의 음이항 모형이 개발되었다. 둘째, 모형별 채택된 독립변수를 활용하여 세 모형의 차이가 비교 분석되었다. 마지막으로 로터리 사고를 예방하기 위해 조명시설, 과속방지턱과 같은 교통안전시설물 설치가 필요한 것으로 평가되었다.

• 한국산업융합학회 논문집
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• 제26권2_2호
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• pp.315-325
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• 2023

Recently, various dynamic risk analysis methods have been suggested for estimating the risk index by predicting the possibility of accidents and damage. It is necessary to maintain and support the safety system for responding to accidents by continuously updating the probability of accidents and the results of accidents, which are quantitative standards of ship risk. In this study, when a LNG leakage that may occur in the LN G Fuel Gas Supply System (FGSS) room during LN G bunkering operation, a reliability physical model was prepared by the change in monitoring data as physical parameters to estimate the accident probability. The scenario in which LNG leakage occur were configured with FT (Fault Tree), and the coefficient of the covariate model and Weibull distribution was estimated based on the monitoring data. The possibility of an LNG leakage, which is the top event of FT, was confirmed by changes in time and monitoring data. A method for estimating the LNG leakage based on the reliability physical analysis is proposed, which supports fast decision-making by identifying the potential LNG leakage at the accident.

• 한국심리학회지 : 문화 및 사회문제
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• 제9권spc호
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• pp.123-147
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• 2003

이 연구에서는 토착 문화심리학을 토대로 사고와 안전에 대한 확률론적인 시각과 결정론적인 시각을 비교 분석하였다. 한국뿐만 아니라 대부분의 선진국이나 개발도상국에서 사고로 인한 사망과 재해는 예방이 가능하다. 이 연구의 첫 번째 부분에서는 사회과학과 응용과학에서 채택되어온 선형의 결정론적인 모형의 한계에 대해 설명하였다. 가정 직장과 사회에서 발생하는 사고와 안전의 확률론적인 속성에 대한 이해를 위해, 토착 문화심리학에서 주장되어온 상호작용 모형이 제안되었다. 두 번째로는 사고와 안전에 관련된 요소들을 검토하였다. 세 번째로는 한국사회에서 사고를 예방하고 안전을 증진하기 위해 확률론적 모형의 활용에 대해 설명하였다.

• 시스템엔지니어링학술지
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• 제19권2호
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• pp.46-58
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• 2023

Deterministic safety analysis is a crucial part of safety assessment, particularly when it comes to demonstrating the safety of nuclear power plant designs. The traditional approach to deterministic safety analysis models is to model the nuclear core using point kinetics. However, this simplified approach does not fully reflect the real core behavior with proper moderator and fuel reactivity feedbacks during the transient. The use of Multi-Physics approach allows more precise simulation reflecting the inherent three-dimensionality (3D) of the problem by representing the detailed 3D core, with instantaneous updates of feedback mechanisms due to changes of important reactivity parameters like fuel temperature coefficient (FTC) and moderator temperature coefficient (MTC). This paper addresses a CEA ejection accident at hot full power (HFP), in which the underlying strong and un-symmetric feedback between thermal-hydraulics and reactor kinetics exist. For this purpose, a multi-physics analysis tool has been selected with the nodal kinetics code, 3DKIN, implicitly coupled to the thermal-hydraulic code, RELAP5, for real-time communication and data exchange. This coupled approach enables high fidelity three-dimensional simulation and is therefore especially relevant to reactivity initiated accident (RIA) scenarios and power distribution anomalies with strong feedback mechanisms and/or un-symmetrical characteristics as in the CEA ejection accident. The Systems Engineering approach is employed to provide guidance in developing the work in a systematic and efficient fashion.

• 대한교통학회지
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• 제19권6호
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• pp.207-218
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• 2001

신호교차로 교통사고는 도시가 발달하고 산업이 고도화됨에 따라 교통혼잡 문제와 함께 심각한 사회문제로 대두되고 있다. 특히 이와 같은 교통사고는 대부분 인적 요인, 차량적 요인, 환경적 요인 등이 상호 복합적으로 작용하여 발생한다. 이전 교통사고와 교통량과의 관계는 운전자 과실과 함께 교통사고 발생에 주요요인으로 작용하고 있다. 본 연구에서는 교통사고 예측모형을 개발하기 위해 1996년부터 1998년까지 3년 동안에 실제 광주광역시 4-지 신호교차로 73개소에서 발생한 교통사고자료를 기초로 하였다. 또한 4-지 신호교차로 교통사고 분석에 단순통계분석과 교차분석 및 다중회귀분석을 사용하였다. 특히 다중회귀분석에는 교차로 사고분석을 위해 사고유형을 종속변수로, 방향별 접근 교통량을 독립변수로 각각 적용하여 교통사고 예측모형을 도출하였다. 그리고 본 연구에서 도출된 예측모형을 이용하여 전라남도 4-지 신호교차로에 대한 교통사고 잦은 지점으로 선정된 30개소를 선택, 사고유형을 분석한 후 교통사고 예측모형에 적용하여 사고모형을 검증하였다. 결론적으로 본 연구에서는 사고유형과 방향별 접근 교통량과의 관계를 이용하여 광주광역시 4-지 신호교차로 교통사고 예측모형을 개발하였고, 향후 연구과제로 타 지역 신호교차로 교통사고 예측모형 연구와 교차로 교통사고에 대한 안전대책 및 안전한 교차로 설계에 대한 지속적인 연구가 수행되어 져야 할 것이다.

• 한국안전학회지
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• 제26권6호
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• pp.130-136
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• 2011

Since out of a lot of traffic problems traffic accidents cause damage to life and properties of people, it stands out as one of traffic problems which needs improvement, and the loss due to traffic accident negatively affects not only the parties to the accident but also the national economy. Thus, continual concern of the government toward traffic safety is getting bigger and lately each local government is preparing a basic plan for traffic safety and vitalizing traffic safety policies. As expanding the responsibility and role of local governments for traffic safety, traffic safety measures which are based on the characteristics of each local government should be studied. Most of analytical methods in the existing traffic accidents prediction models with macroscopic vision focus on socioeconomic variables such as local population and the number of registered vehicles, and present a great deal of prediction error when they are applied in practice. In this context, this study proposed a traffic accident prediction model in respect of macroscopic level for autonomous districts (administrative districts) of Seoul City. The model development was not based on the entire city but on the type of local land usage (development density) whose relationship with traffic accident frequency was analyzed.

• 시스템엔지니어링학술지
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• 제18권2호
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• pp.58-74
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• 2022

Deterministic accident analysis plays a central role in the nuclear power plant (NPP) safety evaluation and licensing process. Traditionally the conservative approach opted for the point kinetics model, expressing the reactor core parameters in the form of reactivity and power tables. However, with the current advances in computational power, high fidelity multi-physics simulations using real-time code coupling, can provide more detailed core behavior and hence more realistic plant's response. This is particularly relevant for transients where the core is undergoing reactivity anomalies and uneven power distributions with strong feedback mechanisms, such as reactivity initiated accidents (RIAs). This work addresses a RIA, specifically a control element assembly (CEA) withdrawal at power, using the multi-physics analysis tool RELAP5/MOD 3.4/3DKIN. The thermal-hydraulics (TH) code, RELAP5, is internally coupled with the nodal kinetics (NK) code, 3DKIN, and both codes exchange relevant data to model the nuclear power plant (NPP) response as the CEA is withdrawn from the core. The coupled model is more representative of the complex interactions between the thermal-hydraulics and neutronics; therefore the results obtained using a multi-physics simulation provide a larger safety margin and hence more operational flexibility compared to those of the point kinetics model reported in the safety analysis report for APR1400. The systems engineering approach is used to guide the development of the work ensuring a systematic and more efficient execution.

• 한국가스학회지
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• 제14권2호
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• pp.27-33
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• 2010

본 논문에서는 국내 가스사고의 발생 환경을 분석하여 가스사고의 재발을 방지하고자 1998년부터 2009년 6월까지 11년 6개월간의 가스사고를 유형별로 분석하였다. 가스사고는 감소하지 않고 지속적으로 발생하고 있고, 사고의 내용에서도 시기별, 날씨 등에 따라 가스사용형태가 변하고 있어 가스의 사용 환경과 가스사고는 밀접할 수밖에 없다. 가스사고는 가스사용이 많은 수도권과 특정 지자체에서 많이 발생하였고, 맑은 날 풍속이 낮고 습도가 중간정도일 때 가장 발생가능성이 높은 것으로 나타났다. 또한, 가스사고 발생 형태의 모형을 관찰한 결과, 가스로 인한 누출, 화재나 폭발 사고의 경우도 날씨와 밀접한 관계가 있을 것으로 판단되는데 이를 날씨와도 연계하여 분석해보면 발생 가능한 전체 가스사고도 예측 가능할 것으로 판단된다.