• 한국화재소방학회논문지
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• 제30권5호
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• pp.116-123
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• 2016

화재모델링을 이용한 목표 대상물의 열적 손상에 대한 정량적 위험성 평가방법이 검토되었다. 이를 위해 대표적인 화재모델로서 FDS가 사용되었으며, 특정 구획 내에서 화원 면적 변화에 따른 전기 케이블의 열적 손상과 관련된 확률이 평가되었다. 보수적 관점에서 적용되고 있는 '최대 손상임계 초과확률'과 손상시간의 정보가 포함된 '손상확률'이 체계적으로 비교되었다. 목표 대상물이 표면온도 및 열유속에 대한 최소 손상기준에 도달하는 순간에 열적 손상이 발생된다는 가정이 적용된 최대 손상임계 초과확률에 비해 본 연구에서 제안된 손상확률은 정량적 화재 위험성을 보다 현실적으로 평가할 수 있음을 확인하였다.

• Industrial Engineering and Management Systems
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• 제13권1호
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• pp.87-100
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• 2014

Risk management is recognized as a significant element in Information Security Management while the failure mode and effects analysis (FMEA) is widely used in risk analysis in manufacturing industry. This paper aims to present the development work of the Information Security FMEA Circle (InfoSec FMEA Circle) which is used to support the risk management framework by modifying traditional FMEA methodologies. In order to demonstrate the "appropriateness" of the InfoSec FMEA Circle for the purposes of assessing information security, a case study at Hong Kong Science and Technology Parks Corporation (HKSTP) is employed. The "InfoSec FMEA Circle" is found to be an effective risk assessment methodology that has a significant contribution to providing a stepwise risk management implementation model for information security management.

• Structural Monitoring and Maintenance
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• 제2권1호
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• pp.49-64
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• 2015

This paper presents a method for assessing the risk of wave run-up and overtopping of existing coastal defences and for analysing the probability of failure of the structures under future hydraulic conditions. The recent UK climate projections are employed in the investigations of the influence of changing environments on the long-term performance of sea defences. In order to reduce the risk of wave run-up and overtopping caused by rising sea level and to maintain the present-day allowances for wave run-up height and overtopping discharge, the future necessary increase in crest level of existing structures is investigated. Various critical failure mechanisms are considered for reliability analysis, i.e., erosion of crest by wave overtopping, failure of seaside revetment, and internal erosions within earth sea dykes. The time-dependent reliability of sea dykes is analysed to give probability of failure with time. The results for an example earth dyke section show that the necessary increase in crest level is approximately double of sea level rise to maintain the current allowances. The probability of failure for various failure modes of the earth dyke has a significant increase with time under future hydraulic conditions.

• 품질경영학회지
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• 제34권1호
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• pp.20-26
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• 2006

In the fields of mechanical reliability application, "zero" or "zero or one" failure tests are most commonly used for demonstrating reliability of a product since they reduce test duration and/or sample size compared to other test methods that guarantees the same reliability of a product with a given confidence level or consumer's risk. The test duration of the "zero or one" failure test is longer than that of "zero" failure test but it has advantage of smaller producer's risk. In this paper a two-stage test is developed that compromises the "zero" and "zero or one" failure tests. The properties of the proposed two-stage test are investigated and the three test methods are compared using a numerical example.

• 한국안전학회지
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• 제30권5호
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• pp.108-113
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• 2015

Plastic injection moulding machine is widely used for many industrial field. It is classified into mandatory safety certification machinery in Industrial Safety and Health Act because of its high hazard. In order to prevent industrial accidents by plastic injection moulding machine, it is necessary for designer to identify hazardous factors and assess the failure modes to mitigate them. This study tabulates the failure modes of main parts of plastic injection moulding machine and how their failure has affect on the machine being considered. Failure Mode & Effect Analysis(FMEA) method has been used to assess the hazard on plastic injection moulding machine. Risk and risk priority number(RPN) has been calculated in order to estimate the hazard of failures using severity, probability and detection. Accidents caused by plastic injection moulding machine is compared with the RPN which was estimated by main regions such as injection unit, clamping unit, hydraulic and system units to find out the most dangerous region. As the results, the order of RPN is injection unit, clamping unit, hydraulic unit and system units. Barrel is the most dangerous part in the plastic injection moulding machine.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 봄 학술발표회 논문집
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• pp.411-418
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• 2000

With the limited amount of budget and time, it is required to determine the priority of investment when there are a large number of hazardous slopes. In this paper, the Rock Slope Risk Rating System is developed based on the combination of the hazard of failure and the damage potential. By applying the proposed rating system to 253 rock slopes in Korean National Highway, it was possible to determine the priority of investment on road cut slopes.

• 한국안전학회지
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• 제33권6호
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• pp.37-41
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• 2018

Process safety technology has developed from qualitative methods such as HAZOP (hazard and operability study) to semi-quantitative methods such as LOPA (layer of protection analysis), and quantitative methods are actively studied these days. Quantitative risk assessment (QRA) is often based on fault tree analysis (FTA). FTA is efficient, but difficult to apply when failure events are not independent of each other. This problem can be avoided using a Markov process (MP). MP requires definition of all possible states, and thus, generally, is more complicated than FTA. A method is proposed in this work that uses an MP model and a Weibull distribution model in order to construct a reliability model for multiple dependent failures. As a case study, a pressure safety valve (PSV) is considered, for which there are three kinds of failure, i.e. open failure, close failure, and gas tight failure. According to recently reported inspection results, open failure and close failure are dependent on each other. A reliability model for a PSV group is proposed in this work that is to reproduce these results. It is expected that the application of the proposed method can be expanded to QRA of various systems that have partially dependent multiple failure states.

• Geomechanics and Engineering
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• 제29권2호
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• pp.193-205
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• 2022

The face stability of shield tunnelling is the most important control index for safety risk management. Based on the reliability of the transparent clay (TC) model test, a series of TC model tests under different buried depth were conducted to investigate the progressive failure mechanism of tunnel face. The support pressure was divided into the rapid descent stage, the slow descent stage and the basically stable stage with company of the local failure and integral failure in the internal of the soil during the failure process. The relationship between the support pressure and the soil movement characteristics of each failure stage was defined. The failure occurred from the soil in front of the tunnel face and propagated as the slip zone and the loose zone. The fitted formulas were proposed for the calculation of the failure process. The failure mode in clay was specified as the basin shape with an inverted trapezoid shape for shallow buried and appeared as the basin shape with a teardrop-like shape in deep case. The implications of these findings could help in the safety risk management of the underground construction.

• 대한토목학회논문집
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• 제37권3호
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• pp.585-592
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• 2017

도심 내 매설된 대다수의 하수관로는 노후가 심각하게 진행되어 파손의 가능성이 높다. 또한, 도시개발의 집중도가 높아 인구밀도나 통행량이 많으므로 하수관로가 붕괴되면 사회 경제적으로 막대한 피해를 입게 된다. 따라서 관로 파손에 의한 사고를 예방하기 위해 사전적인 유지관리가 필요하며, 한정된 재원의 효율적인 활용을 위해 파손의 가능성과 피해의 규모를 동시에 고려한 위험도 기반의 우선순위 결정방안이 제시되어야 한다. 본 연구에서는, 다양한 해외 연구사례를 검토하여 위험도 기반의 하수관로의 조사 우선순위 결정 방법을 도출하였고 도심지 배수분구에 적용 검토하였다. 우선, 서울시 하수관로 GIS DB를 통해 확보 가능한 영향인자를 도출하고, 각 영향인자들의 가중치, 구분항목, 영향점수를 결정하여 가중치 환산법으로 하수관로 파손결과를 산정하였다. 또한, 하수관로의 예상 내용연수 대비 사용연수를 계산하여 파손가능성을 도출하였으며, 내츄럴 브레이크 방법으로 파손결과와 파손가능성을 5등급으로 구분하였다. 위 방법을 서울시 내 위치한 소규모 배수분구에 적용하여 위험도 매트릭스와 위험도 등급을 도출하였으며, 그 결과 전체 대상의 26%가 위험도 4-5등급인 CCTV조사 우선대상으로 선정되었다. 따라서 위험도 기반의 CCTV 우선순위 결정방법을 활용하여 조사가 우선적으로 필요한 대상을 체계적으로 결정할 수 있을 것이다.

• 한국수자원학회논문집
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• 제39권8호
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• pp.659-668
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• 2006

수공구조물의 위험도에 관한 불확실성을 검토하기 위하여 본 연구에서는 빈도해석을 통하여 추정되는 설계홍수량의 분산량을 고려한 불확실성 해석을 실시하였다. Gumbel 분포형을 기본 분포형으로 가정하였으며, 모멘트법, 최우도법, 확률가중모멘트법을 이용하여 각 매개변수 추정방법별로 추정된 설계홍수량에 대한 이론적인 분산량을 산정하였다. 이론적으로 유도한 분산량의 특성을 규명하기 위하며 다양한 표본크기와 설계연한, 비초과확률 및 변동계수조건에 대하여 Monte-Carlo 모의를 실시하고 각 매개변수 추정방법별 비교를 실시하였다. 그 결과 확률 가중 모멘트법을 사용한 경우 위험도에 대하여 상대적으로 가장 작은 상대편의 및 상대제곱근오차를 발생시키는 것으로 나타났으며, 최우도법의 경우에는 상대적으로 큰 표본자료에 대해서는 설계연한 및 비초과확률에 관계없이 작은 상대편의 및 상대제곱근오차를 발생시키는 것으로 나타났다. 또한 다양한 변동계수 조건은 상대편의 및 상대제곱근오차의 측면에서 고려하여 볼 때 거의 영향을 주지 않는 것으로 나타났다.