• Title/Summary/Keyword: risk functions

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Failure Probability Assessment for Risk Analysis of Concrete Gravity Dam under Flood (홍수 시 콘크리트 중력식댐의 위험도 분석을 위한 파괴확률 산정)

  • Cho, Soojin;Shin, Sung Woo;Sim, Sung-Han;Lim, Jeong-Yeul
    • Journal of the Korean Society of Safety
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    • v.31 no.6
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    • pp.58-66
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    • 2016
  • This study aims to estimate the failure probability of concrete gravity dams for their risk analysis under flood situation. To the end, failure modes of concrete gravity dams and their limit state functions are proposed based on numerous review of domestic and international literatures on the dam failure cases and design standards. Three failure modes are proposed: overturning, sliding, and overstress. Based on the failure modes the limit state functions, the failure probability is assessed for a weir section and a non-weir section of a dam in Korea. As water level is rising from operational condition to extreme flood condition, the failure probability is found to be raised up to the warning condition, especially for overturning mode at the non-weir section. The result can be used to reduce the risk of the dam by random environmental variables under possible flood situation.

Development and Implementation of Measures for Structural and Reliability Importance by Using Minimal Cut Sets and Minimal Path Sets (최소절단집합과 최소경로집합을 이용한 구조 및 신뢰성 중요도 척도의 개발 및 적용)

  • Choi, Sung-Woon
    • Journal of the Korea Safety Management & Science
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    • v.14 no.1
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    • pp.225-233
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    • 2012
  • The research discusses interrelationship of structural and reliability importance measures which used in the probabilistic safety assessment. The most frequently used component importance measures, such as Birnbaum's Importance (BI), Risk Reduction (RR), Risk Reduction Worth (RRW), RA (Risk Achievement), Risk Achievement Worth (RAW), Fussel Vesely (FV) and Critically Importance (CI) can be derived from two structure importance measures that are developed based on the size and the number of Minimal Path Set (MPS) and Minimal Cut Set (MCS). In order to show an effectiveness of importance measures which is developed in this paper, the three representative functional structures, such as series-parallel, k out of n and bridge are used to compare with Birnbaum's Importance measure. In addition, the study presents the implementation examples of Total Productive Maintenance (TPM) metrics and alternating renewal process models with exponential distribution to calculate the availability and unavailability of component facility for improving system performances. System state structure functions in terms of component states can be converted into the system availability (unavailability) functions by substituting the component reliabilities (unavailabilities) for the component states. The applicable examples are presented in order to help the understanding of practitioners.

Performance analysis of EVT-GARCH-Copula models for estimating portfolio Value at Risk (포트폴리오 VaR 측정을 위한 EVT-GARCH-코퓰러 모형의 성과분석)

  • Lee, Sang Hun;Yeo, Sung Chil
    • The Korean Journal of Applied Statistics
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    • v.29 no.4
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    • pp.753-771
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    • 2016
  • Value at Risk (VaR) is widely used as an important tool for risk management of financial institutions. In this paper we discuss estimation and back testing for VaR of the portfolio composed of KOSPI, Dow Jones, Shanghai, Nikkei indexes. The copula functions are adopted to construct the multivariate distributions of portfolio components from marginal distributions that combine extreme value theory and GARCH models. Volatility models with t distribution of the error terms using Gaussian, t, Clayton and Frank copula functions are shown to be more appropriate than the other models, in particular the model using the Frank copula is shown to be the best.

A Study on Effect of Army Risk Assessment System for Preventing Safety Accidents (육군 위험성평가체계의 사고예방효과에 관한 연구)

  • Minsuk Park;Byungho Beak;Seungbae Park;Namjoo Jeon
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.47 no.2
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    • pp.84-92
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    • 2024
  • The purpose of this study is to analyze effect of Army Risk Assessment System(ARAS) which is used to prevent safety accident in ROK army. Based on prior research, we select 4 indicators which are related to accident prevention effect and analyze the differences before and after ARAS operation for each indicators by using Paired-Samples T-Test. Also, we analyze the correlation between degree of ARAS operation and status of safety accidents of 112 ROK Army units. We conduct an evaluation of each function within the system using IPA method. The results of this study are as follows; All 4 indicators are improved compared to before ARAS operation, and the differences are statistically significant. Also, there is negative correlation between the degree of ARAS operation and the occurrence of safety accidents. So, the operation of ARAS has a positive effect on preventing safety accidents. Finally among the 15 functions of ARAS, 4 functions require improvement. The findings of this study have implications for proposing necessity of computerized system in enforcing Risk Assessment. Also, whether or not operating ARAS is important, but it is also important to operate it well. Lastly, We propose improvement plans for each function to operate it well.

A Study on the Risk Management Framework for the Long-term Preservation Business of Electronic Records (DRAMBORA를 응용한 전자기록 장기보존 업무 위험관리체계 연구)

  • Yim, Jin-Hee
    • The Korean Journal of Archival Studies
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    • no.27
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    • pp.119-168
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    • 2011
  • This paper proposed risk management approach as a self-audit framework to achieve the goals which might be common among the records management organizations in Korea governmental and public area. After introducing the history and the concept and process of risk management approach and examining DRAMBORA's framework, the processes and the methods of risk management for the electronic records which are customized from DRAMBORA are explained in details: How to define the business context of organizations, how to determine the business functions and activities and related risks, how to assess the level or severity of each risks and some considerations related to risk assessment. As a result, this paper shows that application of DRAMBORA's framework to the electronic records management organizatioins is not only possible but also useful and effective. The critical point for the success of application for DRAMBORA's framwork or the risk management approach itself each organizations which wants to accept that framework should define its own business functions and activities and the goals in respect areas.

Environmental Risk Factors for Children and Adolescents Suffering from Depressive Disorder : Clinical Aspects (소아청소년 우울증에서의 환경적 위험 인자들과 임상적 의미)

  • Lee, Moon-Soo
    • Journal of the Korean Academy of Child and Adolescent Psychiatry
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    • v.21 no.3
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    • pp.141-146
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    • 2010
  • This summary of literature during the past year reviews published studies relating to risk factors for depressive disorders in children and adolescents. Risk factors include environmental toxins, socio-environmental, and genetic factors. As depression has a complex, multifactorial causal mechanism, it is likely that the accumulation and/ or interaction among multiple risk factors lead to depression. Findings related to the result of toxin exposure have been difficult to interpret given that risk factors tend to interact and that higher mental functions are not easily measurable. However, some findings have been consistent. Clinical research data has also shown that the risk for negative outcomes may be modified both by genetic and environmental factors through a gene environment interplay mechanism.

A study on the safety management method based on the risk assessment of KORAIL's level-crossing accidents (선진 위험도 평가 기반의 건널목사고 안전관리 전략 연구)

  • Jung, Do-Won;Wang, Jong-Bae;Lhim, Jea-Eun
    • Proceedings of the KSR Conference
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    • 2010.06a
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    • pp.1732-1750
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    • 2010
  • Operation of KORAIL's level crossing is in charge of KORAIL. As taking over existing level crossing to KORAIL, they do not conduct risk assessments, so we do not know about any possibilities of inner risk. And present operation of safety of the level crossing is just regular checking of reaction and functions of safety equipments physically, we need to react to the changes of what's going on around of level crossing and incestigation of traffic flow and surrounding conditions more spontaneously. So, we have to prepare the strategies against accidents of level crossing cost-effectively based on regular risk assessments for sustainable safety improvements and overcome operational problems of present level crossing's safety. Here, we're going to investigate the level of safety level and present risk factors of the level crossing using risk assessments for accidents/error of the equipments to show operational strategies of level crossing based on risk assessments.

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Evaluation of Overtopping Risks of Levee by using Reliability Analysis (신뢰성 해석에 의한 제방의 월류 위험도 산정)

  • Lee, Cheol-Eung;Park, Dong-Heon;Shim, Jae-Wook
    • Journal of Industrial Technology
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    • v.29 no.A
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    • pp.101-110
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    • 2009
  • Due to frequent occurrence of a localized torrential downpour caused by global warming and change of outflow tendency caused by rapid urbanization and industrialization, risk analysis must be carried out in levee design with uncertainty. In this study, reliability analysis was introduced to quantitatively evaluate the overtopping risk of levee by the uncertainty. First of all, breaking function was established as a function of flood stage and height of levee. All variables of breaking function were considered as random variables following any distribution functions, and the risk was defined as the possibility that the flood stage is formed higher than height of levee. The risk evaluation model was developed with AFDA (Approximate Full Distribution Approach). The flood stage computed by 2-D numerical model FESWMS-2DH was used as input data for the model of levee risk evaluation. Risk for levee submergence were quantitatively presented for levee of Wol-Song-Cheon.

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Quantitative Risk Reduction Model according to SIL allocated by Risk Graph for Railway Platform Door System (Risk Graph에 의해 할당된 SIL에 따른 철도 승강장 도어 시스템의 정량적 Risk 저감 모델)

  • Song, Ki Tae;Lee, Sung Ill
    • Journal of the Korean Society of Safety
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    • v.31 no.5
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    • pp.141-148
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    • 2016
  • There exists required safety integrity level (SIL) to assure safety in accordance with international standards for every electrical / electronics / control equipment or systems with safety related functions. The SIL is allocated from lowest level (level 0) to highest level (level 4). In order to guarantee certain safety level that is internationally acceptable, application of methodology for SIL allocation and demonstration based on related international standards is required. Especially, in case of the SIL allocation method without determining of quantitative tolerable risk, the additional review is needed to check whether it is suitable or not is required. In this study, the quantitative risk reduction model based on the safety integrity allocation results of railway platform screen door system using Risk Graph method has been examined in order to review the suitability of quantitative risk reduction according to allocated safety integrity level.

VaR Estimation of Multivariate Distribution Using Copula Functions (Copula 함수를 이용한 이변량분포의 VaR 추정)

  • Hong, Chong-Sun;Lee, Jae-Hyung
    • The Korean Journal of Applied Statistics
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    • v.24 no.3
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    • pp.523-533
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    • 2011
  • Most nancial preference methods for market risk management are to estimate VaR. In many real cases, it happens to obtain the VaRs of the univariate as well as multivariate distributions based on multivariate data. Copula functions are used to explore the dependence of non-normal random variables and generate the corresponding multivariate distribution functions in this work. We estimate Archimedian Copula functions including Clayton Copula, Gumbel Copula, Frank Copula that are tted to the multivariate earning rate distribution, and then obtain their VaRs. With these Copula functions, we estimate the VaRs of both a certain integrated industry and individual industries. The parameters of three kinds of Copula functions are estimated for an illustrated stock data of two Korean industries to obtain the VaR of the bivariate distribution and those of the corresponding univariate distributions. These VaRs are compared with those obtained from other methods to discuss the accuracy of the estimations.