• Nuclear Engineering and Technology
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• 제50권8호
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• pp.1210-1216
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• 2018

Site or multi-unit (MU) risk assessment has been a major issue in the field of nuclear safety study since the Fukushima accident in 2011. There have been few methods or experiences for MU risk assessment because the Fukushima accident was the first real MU accident and before the accident, there was little expectation of the possibility that an MU accident will occur. In addition to the lack of experience of MU risk assessment, since an MU nuclear power plant site is usually very complex to analyze as a whole, it was considered that a systematic method such as probabilistic safety assessment (PSA) is difficult to apply to MU risk assessment. This paper proposes a new MU risk assessment methodology by using the conventional PSA methodology which is widely used in nuclear power plant risk assessment. The logical failure structure of a site with multiple units is suggested from the definition of site risk, and a decomposition method is applied to identify specific MU failure scenarios.

• 조명전기설비학회논문지
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• 제26권12호
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• pp.21-27
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• 2012

Korean Industrial Standards for lightning protection system complies with IEC standards. However, the standards are applicable only to buildings and structures more than 20 meters in high. Therefore, it is necessary to determine whether lightning protection system should be installed on structures lower than 20 meters high. This paper proposes an efficient method of assessing risk against lightning of structures lower than 20 meters high. The method suggests simplified lightning protection system and provides selecting an appropriate protection level. The suggested method assumes that structure under assessment has no lightning protection system and there is no person around the structure at the moment of lightning stroke. A simplified method of assessing the risk to human within the structure is developed by adopting the general assessment factor. The selection of a protection level is possible by comparing tolerable risk with physical damage risk caused by a direct lightning. Finally, this paper gives ways to establish surge protection measures when a structure with lightning risk is within a radius of 2km from the assessed structure even if this structure requires no lightning protection system.

• Geomechanics and Engineering
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• 제21권2호
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• pp.143-152
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• 2020

Korean society experienced successive earthquakes exceeding 5.0 magnitude in the past three years resulting in an increasing concern about earthquake stability of urban infrastructures. This study focuses on the significant aspects of earthquake risk assessment for the cut-and-cover underground railway station based on two-dimensional dynamic numerical analysis. Presented are features from a case study performed for the railway station in Seoul, South Korea. The PLAXIS2D was employed for numerical simulation and input of the earthquake ground motion was chosen from Pohang earthquake records (M5.4). The paper shows key aspects of earthquake risk for soil-structure system varying important parameters including embedded depth, supported ground information, and applied seismicity level, and then draws several meaningful conclusions from the analysis results such as seismic risk assessment.

• Journal of Information Technology Applications and Management
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• 제21권4호
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• pp.173-186
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• 2014

This study outlines possible risk factors in the SCM of a company and correlates risk assessment, the strategy of risk management, and the supply chain performance. The data is surveyed from an international Korean company and is analyzed by the structure equation model of actual proof. The research model verifies the correlation between the risk assessment, the strategy of risk management, and the supply chain performance as dependent variables after the risk factors of the SCM are defined as independent variables. The research shows that there are consecutive links among the risk factors of the SCM, the risk assessment, and the strategy of risk management. The strategy of risk management was conclusively determined to have an effect on supply chain performance. Therefore, improving the supply chain performance of a company requires the constructive process for risk management based on a correlation between risk assessment and the strategy of risk management.

• 국제학술발표논문집
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• The 3th International Conference on Construction Engineering and Project Management
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• pp.292-301
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• 2009

The employment of risk management theory in Urban Disaster Management System (UDMS) has become an important trend in recent years. The viewpoint of risk management is mainly a comprehensive risk assessment of various internal and external factors, and a subsequent handling of risks. Through continuous and systematic accumulation and analysis of risk information, disaster prevention and rescue system is established. Taking risk management theory as the foundation, Organization for Economic Cooperation and Development (OECD) has developed a series of UDMS in the mega-cities all over the world. With this system as a common platform, OECD cooperates with different cities to develop disaster prevention and rescue system consisting of vulnerability assessment methods, risk assessment and countermeasures. The paper refers to the urban disaster vulnerability assessment and risk management of OECD and the mega-cities of different advanced and developed countries in the world, and then constructs a preliminarily drafted structure for the vulnerability assessment methods and risk management mechanism in the metropolitan districts of Taiwan.

• 한국안전학회지
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• 제31권6호
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• pp.93-98
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• 2016

This study analyzed the inflow characteristics of debris flow according to shape of defensive structure and computed risk index. In order to simulate debris flow, two shapes of defensive structure were considered. Initial mass distribution was set with a rectangular shape and defensive structures were set semi-circular shape and rectangular shape, respectively. It was found that a defensive structure with semicircular shape was more vulnerable to debris impact compared with rectangular shape because the flow mass became concentrated in quadrant part of the inner circle. If the velocity of the debris flow was less than 1 m/s, the risk assessment by FII (Flood Intensity Index) was much appropriate. However, when the movement of debris runout was faster than 1 m/s, the risk index of FHR (Flood Hazard Rating) provided improved classification due to its subdivided hazardous range.

• 한국안전학회지
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• 제20권4호
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• pp.71-77
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• 2005

There are insufficient models that find problems and solutions for accident prevention through risk assessment and suggest safe work process and work instruction from foundation works to finish work for accident decrease. This paper presents a quantitative risk assessment model by analysis of risk factors in each process such as foundation, erection, structure, equipment finish and etc based on accident examples and investigation on actual condition in building. In addition, the safety management system was developed to perform risk assessment of construction and use it for effective safety training for labor.

• 한국지진공학회논문집
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• 제20권7_spc호
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• pp.485-494
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• 2016

The risk-based assessment, also called time-based assessment of structure is usually performed to provide seismic risk evaluation of a target structure for its entire life-cycle, e.g. 50 years. The prediction of collapse probability is the estimator in the risk-based assessment. While the risk-based assessment is the key in the performance-based earthquake engineering, its application is very limited because this evaluation method is very expensive in terms of simulation and computational efforts. So the evaluation database for many archetype structures usually serve as representative of the specific system. However, there is no such an assessment performed for building stocks in Korea. Consequently, the performance objective of current building code, KBC is not clear at least in a quantitative way. This shortcoming gives an unresolved issue to insurance industry, socio-economic impact, seismic safety policy in national and local governments. In this study, we evaluate the comprehensive seismic performance of an low-rise residential buildings with discontinuous structural walls, so called piloti-type structure which is commonly found in low-rise domestic building stocks. The collapse probability is obtained using the risk integral of a conditioned collapse capacity function and regression of current hazard curve. Based on this approach it is expected to provide a robust tool to seismic safety policy as well as seismic risk analysis such as Probable Maximum Loss (PML) commonly used in the insurance industry.

• 한국안전학회지
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• 제29권4호
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• pp.184-190
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• 2014

Decommissioning process of nuclear facilities consist of a sequence of problem solving activities, because there may exist not only working environments contaminated by radiological exposure but also industrial hazards such as fire, explosions, toxic materials, and electrical and physical hazards. Therefore, not a few countries in the world have been trying to develop appropriate counter techniques in order to guarantee safety and efficiency of the process. In spite of that, there still exists neither domestic nor international standard. Unfortunately, however, there are few workers who experienced decommissioning operations a lot in the past. As a solution, it is quite necessary to utilize experts' opinions for risk assessment in decommissioning process. As for an individual hazard factor, risk assessment techniques are getting known to industrial workers with advance of safety technology, but the way how to integrate those results is not yet. This paper aimed to find out an appropriate technique to integrate individual risk assessment results from the viewpoint of experts. Thus, on one hand the whole risk assessment activity for decommissioning operations was modeled as a sequence of individual risk assessment steps which can be classified into two activities, decontamination and dismantling, and on the other, a risk assessment structure was introduced. The whole model was inferred with Fuzzy theory and techniques, and a numerical example was appended for comprehension.

• Toxicological Research
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• 제17권
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• pp.219-225
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• 2001

The basic structure for assessment of potential health risks from environmental chemicals is widely agreed upon, but many of the details of risk assessment procedures differ among practitioners. Government regulatory agencies typically have guidelines or standard procedures for their risk assessments, established to ensure consistency and comparability, to set standards for adequacy, and to embody underlying tenets. In setting and updating such guidelines, each agency takes into account not only the prevailing thinking about appropriate procedures, but also its own goals and responsibilities and the precedents it has set for itself in past analyses. This results in variations in methods, and consequently in characterization of risks, among regulatory assessments, even when they are based on the same data. As a result, adopting existing assessments from a variety of regulatory bodies needs to be done with caution. This paper examines some of the variants in risk assessment approaches among American federal regulatory agencies and relates them to the variations in regulatory responsibilities of those groups. Comparisons to international practices are also drawn. The impact on development of world-wide risk standards is discussed.