• 대한기계학회논문집A
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• 제36권4호
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• pp.373-378
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• 2012

본 논문에서는 공통원인고장을 고려하여 증기터빈 비산확률을 평가하였다. 이 과정에서 저속 및 고속에서 터빈 비산물 발생 경로를 제시하고, 고장수목을 활용하여 비산물 발생빈도를 구하였다. 공통원인고 장을 고려하기 위해서 Alpha Factor 방법론을 사용하였다. 순차 및 비순차 시험에 대해서 각각의 빈도를 비교분석 하였으며, 불확실성을 평가하였다. (1) 고속회전에 의한 연성파괴로 발생하는 터빈비산물 방출빈도는 8.005E-7/year로 평가되었다. (2) 만약, 공통원인고장이 고려되면, 시험방식에 따라 11% 및 33%의 방출빈도 증가를 확인하였다. (3) 사용된 CCF 변수의 불확실성을 고려하면, 터빈방출빈도는 90%의 신뢰도 기준 9.35E-7에서 1.13E-6 사이에 존재함을 알 수 있었다.

• Journal of Chest Surgery
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• 제16권2호
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• pp.184-189
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• 1983

Between 1958 and 1982, 70 patients have undergone pericardiectomy for constrictive pericarditis at the Thoracic Department of Seoul National University Hosp. 58 males and 12 females, with an average age of 27 years [ranging 3 to 60 years], of which 55% were between 10 and 30 years old, were treated. Eight patients died, of whom 4 were in the immediate postoperative period, less that 24 hours after operation. The cause of death was myocardial failure in 3 patients and hypotension during operation in one patient. The remaining four deaths occurred between the fifth and eighteenth postoperative day, and the causes of death varied: bilateral phrenic nerves injury, congestive heart failure, dissemination of tuberculosis, and cardiac arrest. Two patients suffered from congestive heart failure pre-and postoperatively due to the associated valvular heart disease. There were 8 wound infections on which resulted in perichondritis of costal cartilages requiring segmental resection 2 months later. There was one postoperative bleeding requiring immediate reopening for bleeding control. Tuberculosis was confirmed as the cause of constrictive carditis in 27 patients [39%]. Acute pyogenic pericarditis was precursor in 8 patients [11%]. In 2 patients [2.9%], the constrictive pericarditis developed following OHS. Both suffered from congestive heart failure postoperatively due to the residual valvular heart disease. In the others, the cause of the constrictive pericarditis was considered idiopathic or non-specific inflammation.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2003년도 봄 학술발표회 논문집
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• pp.117-122
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• 2003

Every year in domestic slope failure caused by rainfall is happening frequently. Specially, causable failure accident by localized downpour accompanied when summer rainy season period and produces typhoon gets damage of large scale human life and property. Failure happened at slope of 121 places ranged whole country national highway by No.15 typhoon Rusa that strike whole country during 3 days from August 30, 2002. Slope failure that happen by typhoon are judged for major cause to effect of ground saturation and surface water by localized downpour. In this research, failure characteristic was analyzed to target 20 places attaining site investigation among failure slope. As a result, erosions by surface water was construed for major cause of failure and judged for direct relation in failure slope weathering and topography Also, result that analyze inclination of failure part, in the case of ripping rock, inclination of failure side is forming Incline of the lowest 40$^{\circ}$, because surface failure of depth 4m on or so scale happened, it is require that regulating plan gently design standard inclination of weathered rock and soil layer And it is considered that desirable preparation of design standard about measure that help smooth drainage of surface water and can restrain percolation in ground to reduce failure damage by rainfall.

• International Journal of Reliability and Applications
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• 제7권1호
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• pp.41-53
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• 2006

The exact cause of the system's failure is often unknown in the masked system lifetime data. In such type of data, there are two observable quantities, namely (i) the systems time to failure and (ii) the set of systems components that contains the component, which might cause the system to fail. Our objective in this paper is to use the maximum likelihood procedure in the presence of masked data to make inference for the reliability of the system's components. We assume a multi-component series system where each component has a constant failure rate. Different cases that permit for closed form solutions of point estimates are considered. The results obtained in this paper generalize other published results.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.1163-1164
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• 2008

From the complexities and functional/operational expectations, the compositions of PC devices requires Device Drivers to deliver full performance of the Hardware. However, due to quick transition of hardwares and expectations of better performance of the system. As a rest users are exposed of unexpected failures of device drivers which will cause malfunction of the system which consequently cause damages in quantity as well as quality wise. In this paper, the method of calculation and/or forecast to unexpected failure will be suggested. It may not be the answer but can be a guide to calculation to economic damage due to device driver failure.

• Nuclear Engineering and Technology
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• 제33권6호
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• pp.596-604
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• 2001

This paper quantitatively presents the effects of important factors of the probabilistic safety assessment (PSA) of safety-critical digital systems. The result which is quantified using fault tree analysis methodology shows that these factors remarkably affect the system safety. In this paper we list the factors which should be represented by the model for PSA. Based on the PSA experience, we select three important factors which are expected to dominate the system unavailability. They are the avoidance of common cause failure, the coverage of fault tolerant mechanisms and software failure probability. We Quantitatively demonstrate the effect of these three factors. The broader usage of digital equipment in nuclear power plants gives rise to the safety problems. Even though conventional PSA methods are immature for applying to microprocessor-based digital systems, practical needs force us to apply it because the result of PSA plays an important role in proving the safety of a designed system. We expect the analysis result to provide valuable feedback to the designers of digital safety- critical systems.

• 대한임베디드공학회논문지
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• 제19권1호
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• pp.57-64
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• 2024

In the industrial field, robots are used to increase productivity by replacing labors with dangerous, difficult, and hard tasks. However, failures of individual industrial robots in the entire production process may cause product defects or malfunctions, and may cause dangerous disasters in the case of manufacturing parts used in automobiles and aircrafts. Although requirements for early diagnosis of industrial robot failures are steadily increasing, there are many limitations in early detection. This paper introduces methods for diagnosing robot failures using sound-based data and deep learning. This paper also analyzes, compares, and evaluates the performance of failure diagnosis using various deep learning technologies. Furthermore, in order to improve the performance of the fault diagnosis system using deep learning technology, we propose a method to increase the accuracy of fault diagnosis based on an inference window. When adopting the inference window of deep learning, the accuracy of the failure diagnosis was increased up to 94%.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 추계학술대회 논문집(III)
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• pp.103-108
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• 2003

Among welded structure bogies in use for high speed freight car, a part of bogies manufactured in 1999 and 2000 have found problems that failure occurs in its end beam. In case of a freight car a difference of weight between empty and loading conditions are worse than in case of a passenger car. Moreover its brake system is tread brake without second suspension system. A failure of end beam is supposed to be due to loading by brake rather than vertical loading by freight. This failure can make brake system useless and may be a cause of derailment in the worst case. In this study, in order to be proved the cause of failure and to solve the problem it is described that we have measured load history acted on end beam and set up the procedures.

• 열처리공학회지
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• 제18권2호
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• pp.83-90
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• 2005

Failure cause of the fractured engine parts was analyzed by microstructural observation. These parts were failed far earlier than the expected service life. By the stereoscope and SEM examinations of the fractured surface, the fracture modes have been identified as wear and fatigue failure. From the observation of microstructure and microhardness measurements of the failed gears, the probable cause for failures are internal oxidation during using and retained austenite and carbide networks due to heat-treatment, respectively. These defected structures at near surface contributed to the wear and fatigue failure.

• 한국신뢰성학회지:신뢰성응용연구
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• 제6권1호
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• pp.93-103
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• 2006

Basic function of calorifier system is to supply warm water to the vessel. The heater used in the calorifier system plays a very important role in its reliability. The failure mechanism of heater are compared with accelerated life test. The main cause of failed heater is pitting corrosion occurred between the surface of heater and spacer. To prevent the corrosion failure from heater, material of spacer replaces metal(SUS 304) with polymer (Acryl). The life of redesigned heater can guarantee 2.47years of B10 life under the worst condition.