• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2001년도 가을 학술발표회 논문집
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• pp.329-336
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• 2001

The numbers of geogrid-reinforced walls are widely used in Korea. This papers present the results of two failure case histories of geogrid-reinforced segmental retaining walls. The geological background of the construction sites, detailed construction sequences, and the amount of rainfall were examined. The failure of these reinforced walls are caused by the improper drainage system and foundation treatment, too sharpened curvature of corner work, and too high height of wall.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 가을 학술발표회 논문집
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• pp.27-43
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• 2002

This paper described two case studies on large scale failure of cutting slope. The kind of rock in both sites predominated limestone and shale respectively. These cutting slopes located in northern area of Gyongbug Province are composed of very complicated and various rock mass. Geological characteristics, causes of failure, proceeding of security diagnose, maintenance method etc. of two sites were carried out to check the cutting slope stability and to provide reasonable maintenance method. This paper may provide the useful data for engineers related with design and construction of large cutting slope.

• 한국재료학회지
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• 제14권5호
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• pp.322-327
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• 2004

Copper-based leadframe sheets were oxidized in two kinds of hot alkaline solutions to form brown-oxide or black-oxide layer on the surface. The oxide coated leadframe sheets were molded with epoxy molding compound (EMC). After post mold curing, the oxide-coated EMC-leadframe joints were machined to form sandwiched Brazil-nut (SBN) specimens. The SBN specimens were used to measure the fracture toughness of the EMC/leadframe interfaces under mixed-mode (mode I + mode II) loading conditions. Fracture surfaces were analyzed by various equipment to investigate failure path. The results revealed that the failure paths were strongly dependent on the oxide type. In case of brown oxide, hackle-type failure was observed and failure path lay near the EMC/CuO interface with a little inclining to CuO at all case. On the other hand, in case of black oxide, quite different failure path was observed with respect to the distance from the tip of pre-crack and phase angle. Different failures occurred with oxide type is presumed to be due to the difference in microstructure of the oxides.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회/대한산업공학회 2005년도 춘계공동학술대회 발표논문
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• pp.678-685
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• 2005

Estimating parameters of the lifetime distribution is investigated when field failure data are not completely reported. To take into account the reality and the accuracy of the estimates in such a case, the failure reporting probability is incorporated in estimating parameters. Firstly, method of maximum likelihood estimate(MLE) is used to estimate parameters of the lifetime distribution when failure reporting probability is known. Secondly, Expectation and Maximization(EM) algorithm is used to estimate the failure reporting probability and parameters of the lifetime distribution simultaneously when failure reporting probability is unknown. For both case, procedures of estimation are illustrated for single Weibull distribution and mixed Weibull distribution. Simulation results show that MLE obtained by the proposed method is more accurate than the conventional MLE.

• 산업경영시스템학회지
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• 제42권2호
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• pp.28-35
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• 2019

Since guided missiles with the characteristics of the one-shot system remain stored throughout their entire life cycle, it is important to maintain their storage reliability until the launch. As part of maintaining storage reliability, period of preventive test is set up to perform preventive periodic test, in this case failure detection rate has a great effect on setting up period of preventive test to maintain storage reliability. The proposed method utilizes failure rate predicted by the software on the basis of MIL-HDBK-217F and failure mode analyzed through FMEA (Failure Mode and Effect Analysis) using data generated from the actual field. The failure detection rate of using the proposed method is applied to set periodic test of the actual guided missile. The proposed method in this paper has advantages in accuracy and objectivity because it utilizes a large amount of data generated in the actual field.

• 한국환경과학회지
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• 제17권11호
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• pp.1281-1293
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• 2008

This study aims at the estimation of dam failure time and dam failure scenario analysis of and applied to Yeoncheon Dam which was collapsed August 1st 1999, using HEC-HMS, DAMBRK-FLDWAV simulation model. As the result of the rainfall-runoff simulation, the lancet flood amount of the Yeoncheon Dam site was $10,324\;m^3/sec$ and the total outflow was $1,263.90\;million\;m^3$. For the dam failure time estimation, 13 scenarios were assumed including dam failure duration time and starting time, which reviewed to the runoff results. The simulation time was established with 30 minutes intervals between one o'clock to 4 o'clock in the morning on August 1, 1999 for the setup standard for each case of the dam failure time estimation, considering the arrival time of the flood, when the actually measured water level was sharply raising at Jeongok station area of the Yeoncheon Dam downstream, As results, dam failure arrival time could be estimated at 02:45 a.m., August 1st 1999 and duration time could be also 30 minutes. Those results and procedure could suggest how and when dam failure occurs and analyzes.

• Geomechanics and Engineering
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• 제20권3호
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• pp.175-189
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• 2020

A set of relatively simple five local shear and tension failure variables is presented and then implemented into a generalized poroelastic hydromechanical numerical model to analyze failure potential and stability of variably saturated geologic media. These five local shear and tension failure variables are formulated from geometrical relationships between the Mohr circle and the Mohr-Coulomb failure criterion superimposed with the tension cutoff, which approximate together the Mohr effective stress failure envelope. Finally, fully coupled groundwater flow and land deformation in two variably saturated geologic media, which are associated with a slope (Case 1) and a tunnel (Case 2), respectively, and their failure potential and stability are simulated using the resultant hydromechanical numerical model. The numerical simulation results of both cases show that shear and tension failure potential and stability of variably saturated geologic media can be analyzed numerically simply and efficiently and even better by using the five local shear and tension failure variables as a set than by using the conventional factors of safety against shear and tension failures only.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.379-389
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• 2010

It is very important to determine a target probability of failure in reliability based design such as an allowable factor of safety in working stress design because they are indices to judge the stability of structures. We have carried out reliability analyses of nationwide gravity type quay walls and found that sliding and foundation failures of quay walls were dominant failure modes for every case of loads. And a target probability of failure for bearing capacity of foundation of quay wall was also determined in this study. Of several approaches which have been suggested until now, a couple of reasonable approaches were used. Firstly, in order to consider the safety margin of structures which have been executed so far, the reliability levels of existing structures were assessed. And then a mean probability of failure for the quay walls was estimated. In addition, life cycle cost(LCC) analyses for representative structures were performed. Probabilities of failure for several quay walls were calculated with changing the width of each quay wall section. LCC of quay wall which is requiring case by case during the service life was evaluated, and also the optimum probability of failure of quay wall which minimizes LCC was found. Finally, reasonable target probabilities of failure were suggested by comparing with mean probability of failure of existing structures.

• 한국건설관리학회논문집
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• 제9권6호
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• pp.257-267
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• 2008

국내 건설 산업에서 실패정보는 사례중심의 비체계적인 문서형태로 관리되고, 통계적 분석결과 정보수준의 자료로 제시되고 있다. 이는 건설실패정보의 활용을 통하여 건설프로세스가 지속적으로 개선될 수 있다는 긍정적인 측면을 간과한 건설실무자의 인식의 부재에 기인한다. 이에 본 연구는 건설실패정보의 관리 및 활용에 대한 문제점을 인식하고, 반복적으로 발생되는 건설실패를 사전에 예방할 수 있도록 실패정보를 체계적으로 관리, 공유, 학습, 활용할 수 있는 웹 기반 건설실패사례 정보시스템을 구축하기 위한 목적으로 수행되었다. 본 연구에서 개발된 건설실패사례 정보시스템은 웹과 사례기반추론기법을 이용하여 가장 유사한 과거 사례가 검색될 수 있도록 구현하였으며, 건설실패정보를 체계적으로 관리할 수 있고, 실패사례를 통한 간접적 지식습득 및 미래의 건설프로젝트의 실패발생 예방대책을 수립하는데 활용될 수 있을 것이다.

• 융합보안논문지
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• 제18권1호
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• pp.143-155
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• 2018

본 연구는 경호원의 실패요인을 규명하기 위하여 실패귀인을 추출하고, 사례통합분석을 통하여 위해패턴 요인을 도출하였다. 실패귀인은 완전 개방형 질문지(8명)를 시작으로 반구조화 질문지(17명), 폐쇄형 설문지(179명)를 제작하여 SPSS 21.0, AMOS 21.O 통계패키지를 통하여 자료를 처리하였다. 실패귀인과 실패사례 간의 인과관계(경호 실패패턴 요인)를 분석한 결과, 박정희 암살사건에서 불성실(2), 부정적 마인드(1), 업무능력부족(1), 경험부족(2), 조직의 비체계성(2), 사명의식결여(1), 개인주의(1), 업무공유실패(2), 사명의식결여(2) 등 14개의 실패 패턴이 발견되었고, 아웅산 묘소 폭발사건은 불성실(1), 부정적 마인드(1), 업무능력부족(2), 경험부족(2), 개인주의(1), 업무공유실패(1) 등 8개의 실패패턴이 있는 것으로 조사되었으며, 육영수여사 저격사건의 경우, 불성실(2), 부정적 마인드(1), 경험부족(2), 사명의식결여(2), 업무공유실패(1) 등 8개 실패패턴이 있는 것으로 조사 되었다. 3개 사례와 실패귀인 요인간의 관계에서 총 30건의 실패패턴이 발견되었다.