• Fire Science and Engineering
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• v.20 no.4 s.64
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• pp.13-18
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• 2006

The fire protection regulation for the nuclear power plants is based on the qualitative fire hazard assessment and the quantitative fire risk analysis, and the fire risk is managed by the fire protection plan with the appropriate balance among the fire prevention, fire suppression and the minimization of the fire effect. In these days, the zone model or the field model is generally used for the detail evaluation for the fire risk. At this paper, with consideration of the present trend, we evaluate whether the quantitative fire risk analysis and the assessment of fire result for fire areas at nuclear power plants can be possible by use of Fire Dynamics Simulator (FDS) that is the state-of-the-art fire modeling tool. Consequently, it is expected that the quantitative fire risk evaluation propelled by the fire modeling can be available as an applicable tool to improve the core damage frequency as well as the quantitative fire risk analysis.

• Proceedings of KOSOMES biannual meeting
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• 2017.11a
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• pp.109-109
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• 2017

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.105-105
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• 2017

최근 우리나라에서는 국지성호우로 인해 발생하는 돌발홍수에 방어하지 못하는 소규모 저수지에 대한 붕괴사고가 빈발하고 있다. 붕괴된 저수지를 살펴보면, 대체적으로 규모가 작아 체계적인 안전관리가 이루어지지 않거나 경과연수가 50년 이상인 필댐(fill dam) 형식으로 축조된 노후저수지로서 갑작스러운 홍수를 대응하는데 있어 매우 취약한 상태이다. 체계적으로 운영되는 대형댐에 비해 축조기간이 오래된 소규모 저수지의 경우, 저수지에 대한 수문학적 정보가 거의 없거나 미계측되어 보수보강이 필요한 저수지를 선정하거나 정량적인 위험도를 분석하는데 매우 어려운 실정이다. 이러한 이유로 본 연구에서는 노후된 소규모 저수지에 대한 수문학적 파괴인자들을 선정하여 Bayesian Network기반의 소규모 저수지 위험도 분석 모형을 구축하였다. 구축된 모형을 기준으로 고려될 수 있는 다양한 위험인자 및 이들 인자간의 연관성을 평가하였으며, 각각의 노드에 파괴인자를 노드로 할당하여 소규모 저수지의 위험도를 분석하였다. Bayesian Network기법의 도입으로 불확실한 상황을 확률로 표시하고, 복잡한 추론을 정량화된 노드의 관계로 단순화시켜 노드의 연결 관계로 표현하였다. 본 연구에서 제안된 모형은 노후된 소규모 저수지의 수문학적 위험도를 정량으로 분석하는 모형으로서 활용성이 높을 것으로 기대된다.

• Journal of the Korean Society for Railway
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• v.20 no.4
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• pp.550-557
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• 2017

Owing to the established international standards for reliability and safety management of railways and the third-part conformity assessment implementation, quantitative risk assessment focusing on communication system related to railway safety has being implemented. The quantitative risk assessment starts from the establishment of quantitative RAMS requirements; the risk has to be maintained under an acceptable safety level. This paper introduces the risk assessment process based on international standards ; risk assessment was conducted using failure data for railway facilities for about 5.5 years. In addition, based on the results, a scientific risk management method for railway facilities is suggested.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.1
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• pp.76-85
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• 2023

Demand for hydrogen as a renewable energy resource is increasing. However, unlike conventional fossil fuels, hydrogen requires a dedicated refueling station for fuel supply. A risk assessment of hydrogen refueling stations must be undertaken to secure the infrastructure. Therefore, in this study, a risk assessment for hydrogen refueling stations was conducted through both qualitative and quantitative risk assessments. For the qualitative evaluation, the hydrogen dispenser module was evaluated as two nodes using the hazard and operability (HAZOP) analysis. The risk due to filter clogging and high-pressure accidents was evaluated to be high according to the criticality estimation matrix. For the quantitative risk assessment, the Hydrogen Korea Risk Assessment Module (Hy-KoRAM) was used to indicate the shape of the fire and the range of damage impact, and to evaluate the individual and social risks. The individual risk level was determined of to be as low as reasonably practicable (ALARP). Additional safety measures proposed include placing the hydrogen refueling station about 100m away from public facilities. The social risk level was derived as 1E-04/year, with a frequency of approximately 10 deaths, falling within the ALARP range. As a result of the qualitative and quantitative risk assessments, additional safety measures for the process and a safety improvement plan are proposed through the establishment of a restricted area near the hydrogen refueling station.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2008.11a
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• pp.463-466
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• 2008

Owing to the characteristics of the construction industry, large number of risk factors exist in construction projects compared to other industries. In the year 2007, due to industrial disaster, there was a loss of about 70 million number of working days and about 3 trillion won of the economic direct loss Economic loss is estimated up to 16trillion won including the indirect loss. Hence, a countermeasure is required to reduce the loss. However, the existing safety management is inefficient because it is based on experiential safety knowledge in the form of safety index, regulations. The purpose of this research is to improve this problem by proposing a quantitative risk assessment methodology. First, the limitation of existing hazard index is analyzed and subsequently variables for assessing degree of risk is established. Finally, these variables are then combined and a quantitative risk assessment methodology is proposed.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.19 no.6
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• pp.175-184
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• 2009

There have been two methods of estimating computer related security risk such as qualitative and quantitative methods which have distinctive advantages or disadvantages. The former is too narrative and somehow abstract to implement and the latter produces concrete result but needs lots of data, so that it is needed to develop a method overcoming such difficulties. It is advised to mix such two methods in a proper way depending on the conditions of a computer system. In this article, a concept of fuzzy number is employed on the way of mixing the two methods and provide a simple example using fuzzy numbers. Simulation was conducted for an assumed model system and it is demonstrated how to calculated expected and unexpected risk.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.17 no.1
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• pp.95-106
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• 2019

The decommissioning of nuclear power plants should be prepared by quantitative and qualitative risk assessment. Radiological and non-radiological hazards arising during decommissioning activities must be assessed to ensure the safety of decommissioning workers and the public. Decommissioning experiences by U.S. operators have mainly focused on deterministic risk assessment, which is standardized by the U.S. Nuclear Regulatory commission (NRC) and focuses only on the consequences of risk. However, the International Atomic Energy Agency (IAEA) has suggested an alternative to the deterministic approach, called the risk matrix technique. The risk matrix technique considers both the consequence and likelihood of risk. In this study, decommissioning stages, processes, and activities are organized under a work breakdown structure. Potential accidents in the decommissioning process of NPPs are analyzed using the composite risk matrix to assess both radiological and non-radiological hazards. The levels of risk for all potential accidents considered by U.S. NPP operators who have performed decommissioning were estimated based on their consequences and likelihood of events.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2001.11a
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• pp.381-386
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• 2001

RBI(Risk-Based Inspection)는 각각의 설비별로 위험등급 또는 위험도를 산정하고 이에 따라 검사의 우선 순위, 방법, 주기 및 일정계획 등을 수립하여 기술적인 근거에 의해 종합적이고 체계적인 검사를 수행하는 것이다. 이와 같이 RBI는 위험도를 정성적/정량적으로 평가하여 위험의 대부분을 내포하고 있는 30％ 내외의 소수의 설비를 찾아내어 이에 대해 최적의 방법으로 인적, 물적 자원을 집중적으로 투입함으로써 안전성 확보와 함께 경제성을 추구하는 효율적인 기법이라 할 수 있다.(중략)

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.144.2-144.2
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• 2005