• 한국철도학회:학술대회논문집
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• 한국철도학회 2006년도 추계학술대회 논문집
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• pp.1037-1045
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• 2006

In this study, a hazard analysis was performed on the accident related work in the operational railway during 2000-2006 years in order to establish risk assesment procedure for work in the operational railway. As a result of hazard analysis, various hazard events for person accident and operation incident were identified, and risk for the each events was evaluated. Also risk matrix was structurized for setting the risk control criteria.

• 한국생활과학회지
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• 제23권6호
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• pp.999-1012
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• 2014

The purpose of this study is to examine depression in adulthood caused by the influence of negative life events (disaster accident, physical violence and emotional abuse) in pre-adulthood and explore the mediator effect of interpersonal maladjustment. To carry out such task, 974 people who have had negative life event experiences before the age of 18 were chosen based on the data from the 2012 Korean General Social Survey(KGSS) and Stata 10.0 was used to do the analysis. As a result, it was found that there was a direct relationship between negative life events in pre-adulthood and depression in adulthood. Specifically, experiences from an accident or disaster had a direct impact on depression. Moreover, experiences of physical violence and emotional abuse not only had a direct influence on depression, but also through maladjustment, it had an indirectly partial mediator effect that increases the chances of depression. Through this result, it was evident that negative life events from pre-adulthood had a negative effect on continuous interpersonal maladjustment as well as psychological welfare throughout the adulthood. Therefore, there needs to be thorough prevention measures on negative life events in pre-adulthood and strongly take post treatment into consideration. Through building a safe life environment, great deal of social support from social organizations should be prepared systematically.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 춘계학술대회 논문집
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• pp.1174-1179
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• 2007

Train collision and derailment are types of accident that happen with low probability of occurrence but could lead to disastrous consequences including multiple life losses. Risk assessment of the accidents are typically performed per their hazardous events, which are defined as events that cause accidents. This study classifies the train collision and derailment based on the relevant hazardous event, and investigates the causes related to the hazardous events. Finally, the relation of the causes, hazardous events, and the accidents are defined.

• Nuclear Engineering and Technology
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• 제45권6호
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• pp.767-790
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• 2013

MAAP4 is a computer code that can simulate the response of a light water reactor power plant during severe accident sequences, including actions taken as part of accident management. The code quantitatively predicts the evolution of a severe accident starting from full power conditions given a set of system faults and initiating events through events such as core melt, reactor vessel failure, and containment failure. Furthermore, models are included in the code to represent the actions that could mitigate the accident by in-vessel cooling, external cooling of the reactor pressure vessel, or cooling the debris in containment. A key element tied to using a code like MAAP4 is an uncertainty analysis. The purpose of this paper is to present a MAAP4 based analysis to examine the sensitivity of a key parameter, in this case hydrogen production, to a set of model parameters that are related to a Level 2 PRA analysis. The Level 2 analysis examines those sequences that result in core melting and subsequent reactor pressure vessel failure and its impact on the containment. This paper identifies individual contributors and MAAP4 model parameters that statistically influence hydrogen production. Hydrogen generation was chosen because of its direct relationship to oxidation. With greater oxidation, more heat is added to the core region and relocation (core slump) should occur faster. This, in theory, would lead to shorter failure times and subsequent "hotter" debris pool on the containment floor.

• Nuclear Engineering and Technology
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• 제48권1호
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• pp.1-15
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• 2016

For a long time, a top priority in the nuclear industry was the safe, reliable, and economic operation of light water reactors. However, the development of accident-tolerant fuel (ATF) became a hot topic in the nuclear research field after the March 2011 events at Fukushima, Japan. In Korea, innovative concepts of ATF have been developing to increase fuel safety and reliability during normal operations, operational transients, and also accident events. The microcell $UO_2$ and high-density composite pellet concepts are being developed as ATF pellets. A microcell $UO_2$ pellet is envisaged to have the enhanced retention capabilities of highly radioactive and corrosive fission products. High-density pellets are expected to be used in combination with the particular ATF cladding concepts. Two concepts-surface-modified Zr-based alloy and SiC composite material-are being developed as ATF cladding, as these innovative concepts can effectively suppress hydrogen explosions and the release of radionuclides into the environment.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 춘계학술대회 논문집
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• pp.1163-1167
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• 2007

Many railway safety measures are carried out after Daegue subway fire accident. Such as replacement of train interior material, fire extinguish and toxic gas evacuation facilities, exercise on emergency response, setting up of national safety management system, and safety technology research. But these safety measures are not considered by system safety due to lack of risk and hazard information. In order to assess fire risk on system level, we proposed hazard events and causes classification for railway fire accident risk analysis.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 춘계학술대회 논문집
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• pp.1227-1232
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• 2007

The objective of this study is to develop qualification analysis preliminary frame for railway personal injury accident. In this research, we develop accident scenarios to analyze systematically and evaluate quantitatively fatality accident scenarios for railway personal. The accident scenario analysis first identifies the hazardous events and explains the hazardous conditions that surround the accident and cause railway accidents. This method includes a feasibility test, a clustering process and a pattering process for a clearer understanding of the accident situation. Since this method enables an accident scenario analysis to be performed systematically as well as objectively, this method is useful in building better accident prevention strategies. Therefore, this study could serve to reduce railway accidents and could be an effective tool for a hazard analysis.

• Nuclear Engineering and Technology
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• 제53권8호
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• pp.2534-2546
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• 2021

Nuclear emergency preparedness and response is an essential part to ensure the safety of nuclear power plant (NPP). Key support technologies of nuclear emergency decision-making usually consist of accident diagnosis, source term estimation, accident consequence assessment, and protective action recommendation. Source term estimation is almost the most difficult part among them. For example, bad communication, incomplete information, as well as complicated accident scenario make it hard to determine the reactor status and estimate the source term timely in the Fukushima accident. Subsequently, it leads to the hard decision on how to take appropriate emergency response actions. Hence, this paper aims to develop a method for rapid source term estimation to support nuclear emergency decision making in pressurized water reactor NPP. The method aims to make our knowledge on NPP provide better support nuclear emergency. Firstly, this paper studies how to build a Bayesian network model for the NPP based on professional knowledge and engineering knowledge. This paper presents a method transforming the PRA model (event trees and fault trees) into a corresponding Bayesian network model. To solve the problem that some physical phenomena which are modeled as pivotal events in level 2 PRA, cannot find sensors associated directly with their occurrence, a weighted assignment approach based on expert assessment is proposed in this paper. Secondly, the monitoring data of NPP are provided to the Bayesian network model, the real-time status of pivotal events and initiating events can be determined based on the junction tree algorithm. Thirdly, since PRA knowledge can link the accident sequences to the possible release categories, the proposed method is capable to find the most likely release category for the candidate accidents scenarios, namely the source term. The probabilities of possible accident sequences and the source term are calculated. Finally, the prototype software is checked against several sets of accident scenario data which are generated by the simulator of AP1000-NPP, including large loss of coolant accident, loss of main feedwater, main steam line break, and steam generator tube rupture. The results show that the proposed method for rapid source term estimation under nuclear emergency decision making is promising.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.246-251
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• 2005

Accident scenarios analysis is a course to understand, analyze, and describe a process of an accident and behavior pattern of the parties to an accident. The method of accident scenarios is that we described patterns represented between accidents and hazardous conditions, and then provide data to prevent the accident. We have carried out scenarios analysis in various fields so far, but it was not taking account of system. In this research, we made a study on technology of accident scenarios analysis using QFD (Quality Function Deployment) to analyze systematically and evaluate quantitatively types of hazards and scenarios of railway accident. And we analyses accident scenarios of a subject of work-related fatality accident to railway employee and conducted risk assessment for different scenarios. Also we defined relation between unsafe events and hazardous conditions caused to work-related fatality accident, and attempted to quantitatively assess work-related fatality accident and the parties to accidents. The results of this research will be used in analyzing for important causes and contributing factors of work-related fatality accidents at the step of risk assessment of railway system, and quantitatively assessing frequency of work-related accidents and risk.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2006년도 추계학술대회 논문집
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• pp.1126-1131
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• 2006

Risk assessment of a railway system should be periodically conducted managing a large amount of accumulating accident/incident data and scenarios, which generally requires enormous time and efforts. Therefore, special information management system is essential for railway risk assessment, where data needed for decisions on managing the railway safety could be promptly supported. The objective of this study is to develop a railway accident analysis program for risk assessment. The program is application running on the web which links railway accident analysts throughout the railway industry to a central database. Data entered, together with associated code tables. is stored on MS-SQL database. The program uses the concepts of accident, safety events, causes, related factors(vehicle, person, infrastructure, tool/equipment), recommendations to bring together the various elements of railway accidents. The program will be useful in finding hazard conditions, accident scenarios, quantitatively assessing the risk, and providing pertinent risk measures, eventually serving to prevent railway accidents and reduce severities of railway accidents.