• 대한조선학회지
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• 제27권4호
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• pp.67-71
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• 1990

본 논문에서는 신뢰도(reliability)에 제한조건을 두어, 부유식 해양구조물의 주요 부재인 보강된 실린서의 최적설계를 다루었다. 기대되는 총비용을 목적함수로 하여 최소화하였다. 그 총비용은 구조적 비용과 파괴로 인해 예상되는 비용(expected failure cost)으로 구성된다. 여러 설계규정에서 요구하는 설계 요구사항을 역시 제한조건으로서 고려하였다. 본 논문에서는 안전성 측면에서 중요한 구조부재만의 신뢰도를 고려하였고, 시스템의 파괴확율은 일반적으로 부재의 파괴확율보다 상당히 작고 또한 시스템 파괴에 의한 비용을 추정하는 것은 매우 어려우므로 시스템의 파괴는 고려하지 않았다. 또한 파괴모드로써 최종파괴만을 다루었고 피로파괴는 고려하지 않았다. 몇가지 최적설계의 예를 본 논문의 결과로서 보여 주었으며 또한 동일한 구조부재의 설계공식에 따른 최적설계를 비교하기 위해 보강된 실린더의 설계시 현재 사용하는 다른 형태의 설계공식을 갖고 최적설계 결과를 유도하였다. 본 논문에서는 그 결과들로부터 신뢰성해석에 기초한 최적화 과정을 통해 다른 구조물의 설계시 보다 많은 비용의 절감을 꾀할 수 있는 가능성으로부터 그 중요성이 강조되었다.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2011년도 춘계학술대회
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• pp.731-746
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• 2011

The successful and sustainable growth of SMEs depends on their ability of strengthen their competitiveness in quality and cost and service more than anything else as a fundamental of operation. Among these key competitive factors of SMEs, quality is the most critical factor in manufacturing business fields. Because quality strongly influence cost and service performance on this manufacturing business field. There are many different ways to improve the quality performance but it needs proper management decision to choose the best way what can maximize outputs with minimum inputs. And it needs effective measurement methods and some indicators to analysis the quality performance properly. The quality cost is one of the simplest key indicators to measure the quality performance and the effectiveness of quality related management decisions. The major purpose of this study is to diagnose the categorized current level of actual quality cost of local SMEs to maximize their quality management effectiveness through comparing their level with others what's expressed in early studies. In this study, through survey on local SMEs, we found that their average annual quality cost ratio versus turnover - Total amount of annual quality cost divided by annual turnover - is around 3.69% excluded some SME's performances what have different quality control measures with others. And we found some results what corresponded with the early studies on the correlations between those categorized quality costs factors and some discrepancies between some of the literature model and the early case study results as follows. There were negative correlations between the Prevention costs and the External failure costs, and the Appraisal costs and the External failure costs, and there was positive correlation between the Appraisal costs and Internal failure costs same as early studies. But, we couldn't found any strong negative correlations between the Cost of control - Preventive costs & Appraisal costs - and the Cost of Failure of control - Internal & External failure costs -. It reveals not only the lack of effectiveness on their preventive or appraisal activities but also it can reveal there were so many effective ways to prevent the failure costs properly such as some innovative investment on Factory automation includes Error Proofing and more preventive actions to improve the effectiveness of the typical management methods likes CE (Concurrent Engineering), APQP (Advanced Product Quality Planning), FMEA (Failure Mode & Effect Analysis) etc.

• 품질경영학회지
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• 제40권2호
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• pp.186-198
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• 2012

Since Duncan(1956) first proposed an economic design of $\bar{X}$-control charts, most of the succeeding works on economic design of control charts assumed the exponential failure model like Duncan. Hu(1984), however, assumed a more versatile Weibull failure model to develop an economic design of $\bar{X}$-control charts and Banerjee and Rahim(1988) further improved Hu's design by changing the assumption of fixed-length sampling intervals to variable-length ones. In this article we follow the approach of Banerjee and Rahim(1988) but include a pair of warning limits inside the control limits in order to search for a failure without stopping the process when the sample mean falls between warning and control limits. The computational results indicate that the proposed model gives a lower cost than Banerjee and Rahim's model unless the early failure probability of a Weibull distribution is relatively large. The reduction in cost is shown to become larger as the cost of production loss outweighs the cost of searches for a failure.

• 한국신뢰성학회지:신뢰성응용연구
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• 제11권2호
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• pp.167-176
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• 2011

This paper introduces models for preventive maintenance policies and considers periodic preventive maintenance policy with minimal repair when the failure of system occurs. It is assumed that minimal repairs do not change the failure rate of the system. The failure rate under prevention maintenance received an effect by a previously prevention maintenance and the slope of failure rate increases the model where it considered. Also the start point of failure rate under prevention maintenance considers the degradation of system and that it increases quotient, it assumed. Per unit time it bought an expectation cost from under this prevention maintenance policy. We obtain the optimal periodic time and the number for the periodic preventive maintenance by using Nakagawa's Algorithm, which minimizes the expected cost per unit time.

• 한국산학기술학회논문지
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• 제10권6호
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• pp.1346-1352
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• 2009

자동차 부품의 품질보증 비용은 각 시장의 품질보증 영역(warranty region) 내에서 부품이 고장 날 확률에 따라 달라진다. 부품이 고장 날 확률은 각 시장의 다른 스트레스 조건이 비슷하다고 가정할 때 사용비율(usage-rate)에 영향을 크게 받는다. 그러므로 품질보증 비용은 사용비율을 반영한 고장모형을 수립하고 이를 이용한 확률과정 (stochastic process)을 통하여 예측할 수 있다. 본 논문에서는 사용비율을 선형으로 가정한 후 가속실험 모형을 적용하여 2차원 고장모형을 1차원으로 축소시킨다. 이렇게 1차원으로 축소된 고장모형은 사용비율의 함수로 표현될 수 있으므로 사용비율의 변동에 따른 부품의 고장확률 변동을 설명할 수 있다. 이를 통해 새로운 시장의 사용비율을 알면 실측 데이터가 없다고 하더라도 고장확률 분포를 추정할 수 있고 교체되어야 하는 부품일 경우 재생과정(renewal process)으로 비용을 예측할 수 있다. 응용사례에서 실제 두 시장의 품질보증 데이터를 이용하여 이를 분석해 보았다.

• Journal of Electrical Engineering and Technology
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• 제2권2호
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• pp.201-207
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• 2007

As the power industry moves towards open competition, there has been a need for methodology to evaluate distribution power system reliability by using customer interruption costs, particularly in power supply zones under the competitive electricity market. This paper presents an algorithm to evaluate system average interruption duration index, expected energy not supplied, and system outage cost taking into consideration failure rate of the distribution facility and industrial customer interruption cost. Also, to apply this algorithm to evaluate system outage cost presented in this paper, the distribution arrangement of a dual supply system consisting of mostly high voltage customers in an industrial complex in Korea is used as a sample case study. Finally, evaluation results of system interruption cost, system average interruption duration index, and expected energy not supplied in the sample industrial complex area are shown in detail.

• 한국신뢰성학회지:신뢰성응용연구
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• 제6권3호
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• pp.195-203
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• 2006

This paper deals with cost analysis model in periodic maintenance policy. The repair policy with minimal repair is considered as follow : as the occurrence of failure between minimal repair and periodic interval time, unit is replaced by a new unit before the periodic maintenance time comes. Then total expected cost per unit time is calculated according to time delta t in a view of customer's. The total expected costs are included repair and usage cost : operating, fixed, minimal repair, periodic maintenance and new unit expected cost. Numerical example is shown in which failure time of item has Normal distribution.

• 품질경영학회지
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• 제33권3호
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• pp.19-30
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• 2005

Recently many organization to become survival in changing marketplace, they must commit to implementing tools, systems, and quality management techniques. In this paper we develop process method of Team's problem-solving to reduce in failure costs. This paper suggest the step process how to measure quality cost reasonably that works in all types organizations. Or what is continuous improvement? Continuous improvement can be described as the continuous reduction of variation. Variation has many sources(machines, methods, materials, measurements, people, and environments) and cause(special & common in organization). As quality cost are not the answer to every organization financial, or quality-related problem, it's real results are designing & implementing quality cost system might be the answer.

• Journal of Electrical Engineering and Technology
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• 제4권1호
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• pp.43-48
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• 2009

The purpose of the this paper is to make decision of the maintenance priority of power distribution system using Time-Varying Failure Rate(TVFR) with interruption cost. This paper emphasizes the practical use of the reliability indices and interruption cost. To make a decision of maintenance priority on power distribution system equipment, the quantification of the reliability level should be represented as a cost. In this paper, the TVFR of power distribution system equipment applied in this paper utilizes analytic method to use the historical data of KEPCO. From this result, the sensitivity analysis on TVFR of equipment was done for the priority, which represents that high priority of the equipment has more effect on system reliability, such as SAIDI or SAIFI, than other equipment. By this priority, the investment plan is established. In this result, customer interruption cost(CIC) could be extracted, and CIC is used as weighting factor to consider a importance of customer. After that, the result calculated the proposal method in this paper is compared with other priority method, such as lifetime, failure rate or only sensitivity.

• 한국항공운항학회지
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• 제14권2호
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• pp.45-55
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• 2006

Air transportation industry becomes more competitive because that the restrictions on new access to market were eased and related enough for each airline to choose the freight rate and the route without rein. New competitors are pursuing convergence strategy which focuses on low freight rate as a niche strategy for increasing market share by stimulating low cost demand. This strategy is now spreading all over the world such places as Europe, Asia, Oceania and etc. As of December 1, 2004, hundreds of low cost carriers are participating actively in the market and finding their level as a new strategic group in the air transportation industry with expanding their market. In case of USA, however, many airlines, which had newly entered to the market, went into bankruptcy in the mid-1980s. People Express in USA established in 1980 is one of the examples of failure. In case of Japan, Hokkaido International Airline, a typical low cost carrier which established in 1997, filed for bankruptcy. This study is for examining the strategic implication closely through the study on management strategy and cases of failure of low cost carriers.