• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.10
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• pp.49-55
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• 2008

This paper presents a novel evaluation method of life expectancy of power system equipment. The life expectancy means expected remaining lifetime; it can be usefully utilized to maintenance planning, equipment replacement planning, and reliability assessment. The proposed method is composed of three steps. Firstly, a cumulative probability for future years is evaluated for targeted age year. Secondly, the cumulative probability is modeled by well-blown cumulative distribution function(CDF) such as Weibull distribution. Lastly, life expectancy is evaluated as the mean value of the model. Since the model CDF is established in the proposed method, it can also evaluate the probability of equipment retirement within specific years. The developed method is applied to examples of generators of combined cycle power plants to show its effectiveness.

• Korean Journal of Materials Research
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• v.29 no.11
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• pp.670-676
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• 2019

We study substrate support structures and materials to improve uptime and shorten preventive maintenance cycles for chemical vapor deposition equipment. In order to improve the rolling of the substrate support, the bushing device adopts a ball transfer method in which a large ball and a small ball are mixed. When the main transfer ball of the bushing part of the substrate support contacts the substrate support, the small ball also rotates simultaneously with the rotation of the main ball, minimizing the resistance that can be generated during the vertical movement of the substrate support. As a result of the improvement, the glass substrate breakage rate is reduced by more than 90 ~ 95 %, and the equipment preventive maintenance and board support replacement cycles are extended four times or more, from once a month to more than four months, and the equipment uptime is at least 15 % improved. This study proposes an optimization method for substrate support structure and material improvement of chemical vapor deposition equipment.

• Asian Journal of Innovation and Policy
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• v.7 no.1
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• pp.207-234
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• 2018

A manufacturer of a durable good typically purchases supplies, including parts for assembly - that are also useful for repairs - from independent "original equipment suppliers" with which it contracts. The manufacturer is a branded monopolist of its final assembled product. To put into effect also a monopoly of the replacement parts, it must stipulate in its arrangements with independent suppliers of the parts that they not supply such patented parts to any other buyer. Durable good owners would then only be able to obtain their requirements of replacement parts from the same company that supplied the durable. This would amount to a tie-in of replacement parts to the direct purchase of new durables. And that describes the apparently widespread practice of automobile manufacturers in India, as exposed in a recent case before the Competition Commission of India (Samsher Kataria v Honda Siel Cars India Limited and others). Here, I will argue that such tie-in enabled automotive manufacturers to more fully appropriate consumer surplus, which induced them to lower the price of new cars, sell more cars and also sell more repair parts. The tie-in expanded the auto parts industry and promoted new entry. The main restraint on expansion of India's automotive manufacturing is not monopoly. It is government protection in the form of tariffs on automobiles and auto parts.

• Proceedings of the Korean Society for Quality Management Conference
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• 1998.11a
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• pp.277-286
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• 1998

This paper investigates the problem of determining optimal replacement policies for equipment subject to failures with cyclic rates. In many situations, the system failures depend on the operating environmental conditions that vary on time, usually with periodical manners. We use nonhomogeneous Poisson processes whose rate functions exhibit cyclic behavior as well as a long-term evolutionary trend to model the stochastic process of the failures when the rate of occurrence of the failures varies periodically, for example from day to day or between seasons. In this study, we compare optimal policies under the nonhomogeneous process with/without a cyclic component in the failure rate function. The analytical results for various situations are presented along with numerical examples using simulated data.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.2
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• pp.142-147
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• 2009

Conventional HP(high pressure) sodium or Metal-halide lamps have a life span of around one year requiring at least annual replacement and maintenance. High Power LED lights require no regular maintenance further increasing savings on replacement bulbs, access equipment and labour costs. New installations benefit from a substantial reduction in the cost of expensive heavy duty cable required for sodium lighting. Especially, LED light can achieve variable color temperature, high functional performance in the field of street light. There are two main method to achieve variable color temperature function of the street light. one method is using RGB multi-chip LED, the other is using Orange-White LED method. In this paper, it was compare RGB Multi-chip LED with white-orange LED for there characteristics performance.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.29 no.3
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• pp.135-142
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• 2006

Engineers are always concerned with life cycle costs for making important economic decisions through engineering action like reliability of products. Decisions during the reliability growth development of products involve trade-offs between invested costs and its returns. In order to find minimal LCC containing the reliability improvement cost, production cost, repair and replacement costs, and holding cost of spare parts for failure items we suggest in this paper relationship between development cost and sustaining cost in values of growth parameter $\beta$ of AMSAA model. This model is applied to the reliability growth program based on AMSAA model during R&D phase, the warranty activities of items and the block replacement policy for maintenance of items in avionic equipment.

• Clinical and Experimental Pediatrics
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• v.50 no.10
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• pp.938-947
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• 2007

Many dialysis modalities such as peritoneal dialysis (PD), hemodialysis (HD) and continuous hemofiltration or hemodialysis (CRRT) are available for the management of pediatric patients with acute renal failure (ARF). PD is a relatively simple, inexpensive modality and can be used in hemodynamically unstable patients. But, it may not be the optimal therapy for patients with severe volume overload or life threatening hyperkalemia. HD is the preferred modality for the treatment of severe volume overload, severe hyperkalemia, but it needs vascular access. Improvements in the HD equipment have allowed HD to be performend in small children. Recents technological improvements in CRRT therapies have enabled pediatric patients who are less stable to be treated. CRRT is becoming the preferred method of acute therapy in pediatric intensive care units. A sound knowledge of the underlying principles of dialysis and awareness of recent technological advancements in differnet dialysis modalities will hopefully result in improved management of children with ARF.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.675-682
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• 2006

The command of Subway is intended to adjust and control the train operation, and to play a key role of the total passenger transport and all kinds of affairs related to the safe train operation. Also, this can be considered as affairs to be controlled and operated by Total Traffic Control. For the purpose of developing the ATO system in using the new control technology by substituting the conventional ATS equipment, this technical document includes the technical points resulted from doing the replacement construction in the entire section of Subway Line 2 by Seoul Metro. The replacement work with the new ATO System should neither stop nor affect the system under operation while operating the current ATS System. The different systems should not interfere with each other while performing their individual affairs, and be composed to share the important data for the parallel operation. This technology is needed to proceed in assurance of a high degree of reliability.

• Journal of the military operations research society of Korea
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• v.16 no.1
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• pp.142-150
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• 1990

This paper combines research in the areas of replacement and machine interference. Although over the past three decades there has been a great deal of research in the area of optimal replacement for stochastically deteriorating equipment and research dealing with machine interference problems : there has been a lack of research when these two areas are combined. However, the melding of these two well-known areas yields a very practical problem which demands theoretical investigation. In this paper we derive the steady state probabilities with a control limit policy for a two-machine one repairman problem. The control policy is a simple age dependent control described by the control limit, $t^{*}$. Once $t^{*}$ is fixed, the steady state probabilites that one, two, and no machines are working will be obtained.

• Proceedings of the KIEE Conference
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• 2001.05a
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• pp.316-318
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• 2001

Occasionally, equipment in a distribution system fails due to damage from weather, vandalism, or other causes. In addition, it is recommended practice to have some way in which maintenance or replacement of every element in a system can be performed without causing lengthy interruption of electrical service to the customers it feeds. Thus, alternate sources, paths, and configurations of service must be planned so that both failures and maintenance do not affect customer service beyond a reasonable amount. In some cases, planning for alternate routes of service during equipment outages or emergencies -- will be the major aspect influencing selection of a feeder's capacity, type of route, or layout. We want to know the relationship between molt-dividing multi-connection and distribution reliability for contingency support considerations.