• Nuclear Engineering and Technology
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• 제56권3호
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• pp.819-823
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• 2024

The main criteria used in NEI 18-04 to define SSCs as risk-significant include (1) the SSC is required to keep all LBEs within the F-C target, and (2) the total frequency with the SSC failed exceeds 1% of the limit for at least one of the three cumulative risk metrics used for evaluating the integrated plant risk. The first one is a reasonable criterion in determining the risk significant SSCs. However, the second criterion may not be adequate to serve the purpose of determining the risk significance of SSCs. In the second criterion, the cumulative risk metric values representing the integrated plant risk (less the preventive and mitigative effects of the SSC being evaluated) are compared to a risk limit that represents a very small contribution to the overall integrated plant risk, which corresponds appropriately to the contributions from individual SSCs. The easiest approach to redefine the NEI 18-04 definition of risk-significant SSCs in relation to the integrated plant risk metrics is to compare the difference, between the risk metric value calculated with the SSC failed and the risk metric value calculated with the SSC credited, with 1% of the risk limit established for the integrated plant risk metrics.

• Nuclear Engineering and Technology
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• 제44권5호
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• pp.459-470
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• 2012

From the PSA point of view, the Fukushima accident of Japan in 2011 reveals some issues to be re-considered and/or improved in the PSA such as the limited scope of the PSA, site risk, etc. KAERI (Korea Atomic Energy Research Institute) has performed researches on the development of an integrated risk assessment framework related to some issues arisen after the Fukushima accident. This framework can cover the internal PSA model and external PSA models (fire, flooding, and seismic PSA models) in the full power and the low power-shutdown modes. This framework also integrates level 1, 2 and 3 PSA to quantify the risk of nuclear facilities more efficiently and consistently. We expect that this framework will be helpful to resolve the issue regarding the limited scope of PSA and to reduce some inconsistencies that might exist between (1) the internal and external PSA, and (2) full power mode PSA and low power-shutdown PSA models. In addition, KAERI is starting researches related to the extreme external events, the risk assessment of spent fuel pool, and the site risk. These emerging issues will be incorporated into the integrated risk assessment framework. In this paper the integrated risk assessment framework and the research activities on the emerging issues are outlined.

• 경영정보학연구
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• 제4권2호
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• pp.361-376
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• 2002

본 논문은 국내 은행금응기관의 신용위험관리를 보다 효율적이고 과학적으로 지원하기 위한 통합 위험관리시스템의 프레임웍을 제시한다. 즉, 담보 보증중심의 사전관리 위주의 대출관리에서 신용중심의 사후관리 위주의 대출관리로 전환되어야 함에 따라 신용평가시스템, 대출의사결정시스템, 사후관리시스템, 그리고 통합 신용위험관리시스템에 이르기까지 각 단위 시스템이 전체적으로 하나의 시스템으로 통합되어야 한다. 특히, 통합 위험관리시스템은 신용위험을 은행전체의 신용 포트폴리오의 관점에서 측정하고 분석함을 의미한다. 통합 위험관리시스템은 개별 대출기업 혹은 개별 대출에 대한 신용위험을 분석함과 동시에 이를 기초 데이터로하여 은행 전체 신용 포트폴리오의 신용위험 노출정도를 파악한다. 또한, 개별 대출기업의 신용등급 변화로 인한 은행전체 신용위험의 변화를 자동적으로 파악하고 조기 경보함으로써 은행의 총체적인 통합 신용위험관리가 가능하도록 한다.

• 산업공학
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• 제24권1호
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• pp.24-39
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• 2011

In this paper, we study the methodology for the measurement and integration of market risk and credit risk using Copula. We apply the methodology of Rosenberg, and Schuermann(2006) to the assets of pension system. Firstly we estimate dynamics of risk factors and their effects on investment returns, then use the estimated result to simulate future movement of risk factors and distribution of investment returns. Finally we measure integrated risk using integrated return distribution by Copula and simulated future investment return distributions. We found the integrated risk changing with the correlation of risks and investment weights of risks and confirmed the diversification effect of risks. This result is consistent when we use normal Copula and normal marginals, t-Copula and t(3) marginals, and normal Copula and non-parametric marginals. And in the case of non-parametric maginals, larger integrated risk is calculated. It means that use of non-parametric marginals is more conservative.

• 경영과정보연구
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• 제29권4호
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• pp.207-223
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• 2010

본 연구에서는 국내 금융회사중 내부모형을 승인받아 사용하고 있는 국내 은행의 실제 위험유형별 자료를 이용하여 시장위험과 신용위험간 관계를 고려한 통합위험을 측정하였으며, 이를 통하여 위험유형간 분산효과가 존재하는지 검증해 보았다. 검증방법은 법규상 규제자본과 내부모형을 통해 산출되는 시장위험과 신용위험의 단순 합산 및 위험액 자체에 직접 임의의 상관관계를 고려하는 단순통합모형을 이용하여 비교 검증하였다. 실증분석 결과, 다음과 같은 사실들을 확인할 수 있었는데, 먼저 내부모형은 시장위험에서는 평균적으로 규제자본에 비해 40.4%, 신용위험은 45.4%의 분산효과를 보였으며, 통계적으로도 유의한 차이를 보였다. 이는 내부모형의 경우 하위 위험요인간 분산효과로 인하여 규제자본에 비해 필요자본이 작아진 다는 것을 의미한다. 다음으로 실무에서 이용하는 위험액 자체에 임의의 상관관계를 적용하여 산출한 단순 통합위험을 경제적 자본의 대용치인 내부모형의 단순합산과 비교해 본 결과 분산효과는 크지 않았으며, 통계적으로도 유의하지 않은 것으로 나타났다. 이는 은행의 시장위험이 신용위험에 비해 규모면에서 과소하여 분산효과가 크게 나타나지 않는 것으로 설명할 수 있다.

• Nuclear Engineering and Technology
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• 제53권11호
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• pp.3465-3473
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• 2021

For a long time, research into integrated deterministic-probabilistic safety assessment has been continuously conducted to point out and overcome the limitations of classical ET (event tree)/FT (fault tree) based PSA (probabilistic safety assessment). The current paper also attempts to assert the reason why a technical transformation from classical PSA is necessary with a re-interpretation of the categories of risk. In this study, residual risk was classified into interpolating- and extrapolating-censored categories, which represent risks that are difficult to identify through an interpolation or extrapolation of representative scenarios due to potential nonlinearity between hardware and human behaviors intertwined in time and space. The authors hypothesize that such risk can be dealt with only if the classical ETs/FTs are freely relocated, entailing large-scale computation associated with physical models. The functional elements that are favorable to find residual risk were inferred from previous studies. The authors then introduce their under-development enabling techniques, namely DICE (Dynamic Integrated Consequence Evaluation) and DeBATE (Deep learning-Based Accident Trend Estimation). This work can be considered as a preliminary initiative to find the bridging points between deterministic and probabilistic assessments on the pillars of big data technology.

• Nuclear Engineering and Technology
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• 제47권4호
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• pp.461-471
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• 2015

Recently, the estimation of the social cost of energy sources has been emphasized as various novel energy options become feasible in addition to conventional ones. In particular, the social cost of introducing measures to protect power-distribution systems from power-source instability and the cost of accident-risk response for various power sources must be investigated. To account for these risk factors, an integrated societal risk assessment framework, based on power-uncertainty analysis and accident-consequence analysis, is proposed. In this study, we applied the proposed framework to nuclear power plants, solar photovoltaic systems, and wind-turbine generators. The required capacity of gas-turbine power plants to be used as backup power facilities to compensate for fluctuations in the power output from the main power source was estimated based on the performance indicators of each power source. The average individual health risk per terawatt-hours (TWh) of electricity produced by each power source was quantitatively estimated by assessing accident frequency and the consequences of specific accident scenarios based on the probabilistic risk assessment methodology. This study is expected to provide insight into integrated societal risk analysis, and can be used to estimate the social cost of various power sources.

• Nuclear Engineering and Technology
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• 제50권5호
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• pp.627-638
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• 2018

This article describes an integrated Level 1-Level 2 probabilistic risk assessment (PRA) methodology to evaluate the radiological risk during postulated accident scenarios initiated during the decommissioning phase of a typical Mark I containment boiling water reactor. The fuel damage scenarios include those initiated while the reactor is permanently shut down, defueled, and the spent fuel is located into the spent fuel storage pool. This article focuses on the integrated Level 1-Level 2 PRA aspects of the analysis, from the beginning of the accident to the radiological release into the environment. The integrated Level 1-Level 2 decommissioning PRA uses event trees and fault trees that assess the accident progression until and after fuel damage. Detailed deterministic severe accident analyses are performed to support the fault tree/event tree development and to provide source term information for the various pieces of the Level 1-Level 2 model. Source terms information is collected from accidents occurring in both the reactor pressure vessel and the spent fuel pool, including simultaneous accidents. The Level 1-Level 2 PRA model evaluates the temporal and physical changes in plant conditions including consideration of major uncertainties. The goal of this article is to provide a methodology framework to perform a decommissioning Probabilistic Risk Assessment (PRA), and an application to a real case study is provided to show the use of the methodology. Results will be derived from the integrated Level 1-Level 2 decommissioning PSA event tree in terms of fuel damage frequency, large release frequency, and large early release frequency, including uncertainties.

• International Journal of Computer Science & Network Security
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• 제24권5호
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• pp.73-78
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• 2024

COVID-19 pandemic outbreak increased the use of Internet of Medical Things (IoMT), but the existing IoMT solutions are not free from attacks. This paper proposes a secure and resilient framework for IoMT, it computes the risk using Risk Impact Parameters (RIP) and Risk is also calculated based upon the Threat Events in the Internet of Medical Things (IoMT). UICC (Universal Integrated Circuit Card) and TPM (Trusted Platform Module) are used to ensure security in IoMT. PILAR Risk Management Tool is used to perform qualitative and quantitative risk analysis. It is designed to support the risk management process along long periods, providing incremental analysis as the safeguards improve.

• 한국수소및신에너지학회논문집
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• 제34권6호
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• pp.728-733
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• 2023

Efforts are continuing to change from fossil fuels used to hydrogen energy society. In order to become a hydrogen society, stable production and real-life applicability are important. As a result, hydrogen generation system linked to fuel cell are being developed. Through this, it is expected that production to power generation will be possible where desired by utilizing the existing urban gas piping network. Hydrogen generation system and hydrogen fuel cell have been subjected to risk assessment and have already been commercialized, but no risk assessment has been conducted on the integrated system linking them. Therefore, it is intended to secure its safety by conducting a risk analysis on the integrated system.