• The KSFM Journal of Fluid Machinery
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• v.19 no.3
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• pp.33-36
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• 2016

The investigation on the verification of availability simulation for small-scale plant has been carried out. This study focuses on the availability variation induced by number of equipment and iteration with failure density function. The equipment classification of small-scale plant and failure type and the methodologies on Monte-Carlo simulation are established. The availability deviation with programs showed under Max. 1.7% for the case of normal function. This method could be used to availability evaluation of small-scale plant, but calibration of the failure density function is necessary for general application.

• Journal of the Korean Operations Research and Management Science Society
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• v.27 no.3
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• pp.115-133
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• 2002

In this paper, 15 South Korean telecommunications service failure cases were analyzed. Through the in-depth case study, 8 factors were found to be the major causes contributing to the telecommunications service failure. They were (1) ineffective marketing, (2) poor demand forecasting due to misjudgment of customer preference, (3) failure to satisfy technical specifications, (4) loss of cost advantage due to the price cut of competing services or new entry with lower price, (5) loss of utility advantage due to the increased utility of competing services or new entry with higher utility (6) decrease of market attractiveness due to change of customer preference, (7) impact of government policy, and (8) insufficient or low quality of contents. Additional analysis was done to derive managerial implications to the new telecommunications service development strategy. The findings from the paper will provide valuable Insight to the successful Implementation of new service development and service provisioning processes.

• Proceedings of the KIEE Conference
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• 2006.11a
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• pp.9-11
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• 2006

This paper suggests a revision method for historical fault data using Proportional Aging Reduction(PAR) to consider maintenance effect in time-varying failure rate. In order to product time-varying failure rate, the historical fault data are necessary. However, the maintenance record could be left out in historical data by spot operator's mistake. In this case, the failure rate is produced less than the average failure rate for increasing equipments' life-time by maintenance effect. Hence, it is necessary for new time-varying failure rate to extract maintenance effect from the existing fault data. In this paper, the revision method to reduce equipments' life-time, adversely using PAR among three techniques to consider maintenance effect.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.511-518
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• 2000

Characteristics of joint orientation, length, spacing and their distribution are very important factors for slope stability, Especially, the effect of joint spacing is an essential factor of slope stability. This study is to analyze the effect of joint spacing in cases of sliding and toppling, which is a typical failure mode. Joint spacing can divided into vertical spacing(spacing) and horizontal spacing(gap). And then, the spacing/length ratio of joint directly affect rock slope failure. When the ratio is below 0.05, the possibility of failure is rapidly increased. In case of toppling, the possibility of failure depends on the ratio of spacing to height of slope ratio slope. As the ratio decreases, the possibility of toppling failure increased. The critical ratio of spacing to height of slope is determined by the dip angle of the slope and the orientation of joint sets.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.777-780
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• 2005

The bench of cut-slope is necessary to stabilizing. But it is possible to be a weak zone in slope. When a small scale failure is occurred in a bench, it influence a large scale failure of slope. So when it is found out any unstable factor, weathering of rock, a direction of joint in a bench, if the bench is reinforced suitably, the holly failure is prevented in cut-slope

• Proceedings of the KIEE Conference
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• 2002.07a
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• pp.503-507
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• 2002

This paper describes the symptoms with the failure causes of pole transformers analyzed at KEPCO branch offices' request in 2001, and ultimately aims for devising proper countermeasures against the failures. The failure causes are generally divided into problems in manufacturing, mounting and operating. The pole transformers encounter the failure with unique mechanisms. To verify the mechanisms to failures and help devise proper countermeasures, a flowchart is proposed based on the authors' experience and foreign case studies. The failure causes of pole transformers can be analyzed more exactly by using the flowchart.

• Proceedings of the Korean Reliability Society Conference
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• 2011.06a
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• pp.21-26
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• 2011

Initial reliability prediction done by calculation would be more practical if support by evidence from customer usage profile and field failure data to improve the prediction. Thus, the consistency of the design and the product would be practically validated. In this paper, it will address rationale and method to decide on Acceleration Factor (AF) to be used in Accelerated Life Test (ALT) through usage profile and field failure. The case study of tractor transmission is used to demonstrate the method which data obtained from surveys done on farmers, field visits and field failure data from service center. By considering all the elements, it will determine more relevant AF which indicates the real use conditions of the component.

• Journal of Information Technology Applications and Management
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• v.13 no.2
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• pp.17-28
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• 2006

The SRGM has been studied under the assumption that S/W reliability can grow as the fault causing failure is removed even during operational phase because the debugging is available. On the other hand, some papers insist on the uniform failure rate during operational phase because the debugging may not be available in case of universal software. The phenomenon, however, has been observed informally many times that the products S/W reliability grows as the time goes by even without any debugging in point of customer view. I propose the simple approaching method to model the S/W reliability phenomenon that the failure rate reduces as time goes on without modifying the existing reliability model in this paper.

• Journal of Veterinary Clinics
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• v.25 no.6
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• pp.510-513
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• 2008

Two dogs were referred due to vomiting, depression and anorexia after ingestion of xylitol gum. Both dogs were presented with hepatic failure and one dog had concurrent renal failure. Aggressive supportive treatment was performed, but these dogs died. Necropsy of one dog revealed acute hepatic necrosis, severe renal damages, and hemoperitoneum. This case report demonstrates potential hazard of xylitol toxicity for dogs with clinicopathological and pathological findings.

• International Journal of Reliability and Applications
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• v.2 no.1
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• pp.1-26
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• 2001

The purpose of this paper is to introduce a proportional reversed hazard rate model, in contrast to the celebrated proportional hazard model, and study some of its structural properties. Some criteria of ageing are presented and the inheritance of the ageing notions (of the base line distribution) by the proposed model are studied. Two important data sets are analyzed: one uncensored and the other having some censored observations. In both cases, the confidence bands for the failure rate and survival function are investigated. In one case the failure rate is bathtub shaped and in the other it is upside bath tub shaped and thus the failure rates are non-monotonic even though the baseline failure rate is monotonic. In addition, the estimates of the turning points of the failure rates are provided.