• 한국품질경영학회:학술대회논문집
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• 한국품질경영학회 2004년도 품질경영모델을 통한 가치 창출
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• pp.85-89
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• 2004

This brief paper is an application of HALT(High Accelerated Life Test) and FA(Failure analysis) to improvement of STN LCD module. Before HALT the result of environmental test is good. So, we choose the technique of HALT to evaluate reliability. After HALT and Fa, we suggest some methods to improve reliability

• 대한방사선기술학회지:방사선기술과학
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• 제9권1호
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• pp.131-135
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• 1986

The reciprocity law failure of the blue sensitive screen-film system was treasured, by authors. As a result, it has been found that reciprocity law failure is mote likely to occur at lower exposure, lower density and higher development temperature.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
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• pp.761-774
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• 2009

To address the importance of geotechnical investigation, failure cases are taken up for consideration. One of them awaken this country to the importance of exact geotechnical investigation at the cost of many lives. Other failures were also occurred as the result of insufficient geotechnical investigation or missing some facts given by geotechnical investigation. A case which shows the unpredicted and unaccustomed settlement at bridge abutment introduced to emphasize the importance of exploring unknown nature of local soils.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2005년도 춘계학술대회 논문집
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• pp.228-233
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• 2005

The damage of the pressure courage by degradation can become the reason of unexpected break down or failure accident and it is very important because safety accident, the production loss, environmental pollution, social problems are occur. Consequently The result to investigat of failure accident for domestic pressure vessel, the factor of degradation is SCC, Sorrosion, Cavity, Crack.

• 한국통신학회논문지
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• 제22권4호
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• pp.748-760
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• 1997

The handoff failure probability has to be enhanced efficiently to enhance the performance of PCS system. In this paper a new scheme called velocity adaptive handoff algorithm for reducing handoff failure probability and maintaining the carried traffic constantly in PCS systems, by assigning low handoff threshold value for high mobility calls, and assigning high handoff threshold value for low mobility calls, is presented. The performance of evaluation of this new scheme is carried out in terms of tranffic characteristics. Also velocity estimation algorithm for this new scheme is presented. According to the result, the handoff failure probability of velocity adaptive handoff algorithm is enhanced about 60%.

• 한국지반공학회지:지반
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• 제12권6호
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• pp.37-50
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• 1996

본 연구는 국내 고속도로의 암반사면의 현장조사를 실시하여 암반사면의 붕괴형상 및 특징을 암종 및 지질구조에 따라 분류하였으며 사면의 암종에 따른 붕괴규모, 붕괴시기 등을 분류하고 불안정한 사면에 영향을 주는 주요 지질구조에 대해 분석하였다. 연구결과, 붕괴 빈도가 높은 사면은 한반도의 남동측에 나타나는 중생대 백악기 퇴적암층과 경기일원 및 강원도 일원의 비교적 넓게 분포하고 있는 선캠브리아기의 편마암, 편암지대에 분포하는 것으로 나타났다. 암종에 따른 붕괴유형은 화성암이 낙석, 평면파괴, 토층유실, 원호파괴의 붕괴유형을 보이나 붕괴빈도가 비교적 낮고 퇴적암에서는 평면파괴가 우세하게 나타났으며 계일층의 차별적인 풍화에 의해 붕락형의 붕괴유형을 보이기도 하였다. 그리고 변성암에서는 암질불량으로 인한 원형파괴, 단층구조 및 엽리 등으로 인한 쐐기파괴, 평면파괴양상을 보였다. 지질구조에 따른 붕괴는 퇴적암에서는 주로 층리에 의해서는 붕괴가 발생되었으며 화성암에서는 절리, 그리고 변성암에서는 단층과 암질불량에 의한 붕괴가 우세한 것으로 나타났다.

• 상하수도학회지
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• 제10권1호
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• pp.96-111
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• 1996

The failure of water pipelines is progressed by several compound factors and the collection and analysis of data about pipeline failure are inevitable for effective pipeline rehabilitation. Data analysis of pipeline failure was already performed in USA and Europe. Based on such phenomena, failure characteristics about metropolitan pipelines in Korea were analyzed: The conclusions of this study are as followings. 1. The failure cause of pipelines can be classified into natural cause and artificial cause. Artificial cause is 32% of total causes, so artificial failure as several constructions happens frequently in Korea. Although the failure by old pipe is greatest of any other causes m classtfied cause, failure cause is not classified in detail now. 2. The damaged part of pipelines is affected by cities, distribution system inventory, bedding conditions, and so on. In this study, the failure of pipeline body(67%) is greater than the failure of pipeline joint(33%) in natural failure. 3. In regard to pipe materials, failure rate of DCIP(0.8456), PEP(0.7288), and GSP(0.6643) is greater than that of CIP(0.3985) and CWSP(0.2348). 4. Usually, faIlure rate is increased in proportion to diameter of pipeline. In this study, CIP, DCIP, and CWSP have clear trends. But the trends of PEP is reverse, the case of GSP, HP is obscure due to data shortage. 5. There are no direct relationships between burial age and failure rate of pipelines. 6. Annual breaks and winter(Nov.~Feb.) breaks of pipelines are investigated. As a result, WInter breaks to annual breaks of CIP is 51.3%(Seoul), 51.1%(Taegu),38.7%(Pusan). This phenomena have direct correlation with average winter temp. of cities.

• Geomechanics and Engineering
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• 제13권1호
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• pp.63-77
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• 2017

The failure mechanism of a deep hard rock tunnel under high geostress and high geothermalactivity is extremely complex. Uniaxial compression tests of granite at different temperatures were conducted. The complete stress-strain curves, mechanical parameters and macroscopic failure types of the rock were analyzed in detail. The brittleness index, which represents the possibility of a severe brittleness hazard, is proposed in this paperby comparing the peak stress and the expansion stress. The results show that the temperature range from 20 to $60^{\circ}C$ is able to aggravate the brittle failure of hard rock based on the brittleness index. The closure of internal micro cracks by thermal stress can improve the strength of hard rock and the storage capacity of elastic strain energy. The failure mode ofthe samples changes from shear failure to tensile failure as the temperature increases. In conclusion, the brittle failure mechanism of hard rock under the action of thermal coupling is revealed, and the analysis result offers significant guidance for deep buried tunnels at high temperatures and under high geostress.

• 한국신뢰성학회:학술대회논문집
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• 한국신뢰성학회 2001년도 정기학술대회
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• pp.337-337
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• 2001

High voltage ceramic capacitors are widely applied in power electronic circuits, such as filters, snubbers, and resonant circuits, due to their excellent features of high voltage endurance and low aging. This paper presents a result of failure analysis and reliability evaluation for high voltage ceramic capacitors. The failure nodes and failure mechanisms were identified in order to understand the failure physics in a component. The causes of failure mechanisms for zero resistance phenomena under withstanding voltage test in high voltage ceramic capacitors molded by epoxy resin were studied by establishing an effective closed-loop failure analysis. Also, the condition for dielectric breakdown was investigated. Particular emphasis was placed on breakdown phenomena at the ceramic-epoxy interface. The validity of the results in this study was confirmed by the results of accelerated testing. Thermal shock test as well as pressure cooker test for high voltage ceramic capacitor mounted on a magnetron were implemented. Delamination between ceramic and epoxy, which, might cause electrical short in underlying circuitry, can occur during curing or thermal cycling. The results can be conveniently used to quickly identify defective lots, determine mean time to failure (MTTF) of each lot at the level of Inspection, and detect major changes in the vendors processes.

• 한국지반환경공학회 논문집
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• 제17권5호
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• pp.5-16
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• 2016

A rainfall induced slope failure is a common natural hazard in mountainous areas worldwide. Sudden and rapid failures which have a high possibility of occurrence in a steep slope are always the most dangerous due to their suddenness and high velocities. Based on a series of experiments this study aimed to determine a critical angle which could be considered as an approximate threshold for a sudden failure. The experiments were performed using 0.42 mm mean grain size sand in a 200 cm long, 60 cm wide and 50 cm deep rectangular flume. A numerical model was created by integrating a 2D seepage flow model and a 2D slope stability analysis model to predict the failure surface and the time of occurrence. The results showed that, the failure mode for the entire material will be sudden for slopes greater than $67^{\circ}$; in contrast the failure mode becomes retrogressive. There is no clear link between the degree of saturation and the mode of failure. The simulation results in considering matric suction showed good matching with the results obtained from experiment. A subsequent discarding of the matric suction effect in calculating safety factors will result in a deeper predicted failure surface and an incorrect predicted time of occurrence.