• Journal of the Korean Data and Information Science Society
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• 제16권4호
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• pp.725-733
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• 2005

A system subject to random shocks is considered. The shocks arrive according to a Poisson process and the amount of each shock is exponentially distributed. In this paper, a periodic inspection policy for the system is compared with a random inspection policy. After assigning several maintenance costs to the system, we calculate and compare the long-run average costs per unit time under two policies.

• 품질경영학회지
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• 제20권2호
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• pp.1-10
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• 1992

In this paper, we study a joint lot sizing and inspection policy under an EPQ(Economic Production Quantity) model where a random proportion of units are defectives. Those units can be discovered only through costly inspection. The problem is thus bivariate : both lot size and fraction to inspect are to be chosen. We first analyze a model in which the only penalty for uninspected defectives is financial, and then consider a model where defectives units cannot be used and thus must be replaced by non-defective ones. As a result it can be proved that this inspection policy costs economically and is to be decided effectively for the Economic Production Quantity constraining the fraction to inspect.

• 산업경영시스템학회지
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• 제13권21호
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• pp.19-24
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• 1990

This paper deals with a problem of choosing an optimum inspection period for an equipment with two stages of failures. Stage I failure which can be detected only through inspection detenorates the equipment and causes critical stage II failure after a random period of time. The expected average cost function is obtained and an optimum inspection policy is discussed. A numerical example is also worked out.

• 한국경영과학회지
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• 제16권1호
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• pp.13-34
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• 1991

A production/inventory system is considered in which a production facility produces one type of product. The demand for the product is given by a compound Poison process and is supplied directly from inventory when inventory is available and is lost when inventory is out of stock. The processing time to produce one item is assumes to follow a general distribution. An (s, S) policy is considered in which production stops at the instant the stock on hand reachs S and the setup of the production facility begins at an inspection point when the stock on hand drops to or below s for the first time. The time interval between two successive inspection points during a non-production period is a random variable which follows a general distribution.

• 대한산업공학회지
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• 제21권4호
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• pp.555-570
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• 1995

We consider a preventive replacement policy for a cold-standby system with N components, in which only one component is in operation at a time. If the component in operation fails, a standby component is immediately switched into operation. If all components fail, the system fails. The system is inspected at random poins in time to determine whether it is to be replaced or not. If the number of failed components at the time of inspection exceeds a threshold value r, the system is replaced. Otherwise the decision is put off until the next inspection point arrives. Under the cost structure which includes a replacement cost, a system down-time cost and a holding cost of the components, we develop an efficient procedure to find the optimal control values N and r, which minimize the expected cost per unit time.

• 한국경영과학회지
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• 제22권1호
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• pp.123-140
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• 1997

In this paper we consider closed flow line systems with samploing inspections. The total number of parts in the system is assumed to be N. The processings carried out of each station do not always meet the requirement of quality. Therefore, upon completion of its processing at each station, a part is inspected to determine whether the processings meet the requirement of quality or not. We assume that inspection are done on a random basis. If a part is found to be defective by an inspection, it is fed back to the apropriate station. Two different cases will be considered in this study : a three-station flow line system with infinite buffers and a two-station flow line system with finite buffers. For each case, we will develop an exact method to obtain the performance measures such as throughput, machinen utilization, average outgoing quality and manufacturing lead time. For the case of the two-station flow line system ith finite buffers, we will also develop an approximation method using a stage-aggregation technique. Then using buffers, we will also develop an approximation method using a stage-aggregation technique. Then using these results, we will try to find an optimal inspection policy which maximizes the expected net profit under a certain cost structure. Although we present the results only for the two or three station flow line system in this paper, the results obtained in this paper can be extended easily to the system which consists of more than two or three stations.

• 대한본초학회지
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• 제27권2호
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• pp.25-29
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• 2012

Objectives : This article reviews a solution preventing the illegal distribution of herbal medicine in common use for food and medicine and risks on public health by conducting safety management of food and medicine. Also, this article would like to contribute to improvement of public health treating diseases in compliance with accurate diagnosis and prescription of Oriental Medicine Doctor("OMD")'s. Methods : An approach in this research can be categorized into two : first, to examine the current administrative situation and problems of herbal medicine in common use for food and medicine based on policy documents of Ministry of Health and Welfare and Korea Food and Drug Adminstration("KFDA") and academic articles of the herbal medicine;second, to find reasonable administrative solutions to solve the problems. Solutions : A solution is to strengthen the management level of herbal medicine in common use for food and medicine by selecting 117 items as target items requiring concentrated management. In case herbal medicine is imported for food, KFDA strengthens the quality management level of herbal medicine by making use of inspection frequency at random, collecting and verifying herbal medicine on the market. However, KFDA decides to maintain current different quality specification system of food and medicine reflecting a civil complaint that quality specification of food and medicine should separately managed according to the purpose of use. Herbal medicine as medicine that is functioned as treating diseases and alleviating symptoms, unlike herbal medicine for food, can cure all kinds of diseases by recovering inner balance of human body, making use of other properties of herbal medicine. Medicine has its own properties. If a doctor uses properties of medicine appropriately, he cures diseases. If a doctor uses herbal medicine inappropriately. he may damage human body. Thus, whether side effects of medicine depend on a doctor who uses herbal medicine. Conclusions : All herbal medicine will be supplied into the market after strict safety control of manufacturers of herbal medicine according to the revised Pharmaceutical Affairs Act, beginning in April, 2012. Thus, people can take safer and more reliable herbal medicine through strengthening safety management of herbal medicine and improving quality and transparency in the distribution system. Herbal medicine should appropriately be prescribed by licensed OMD because herbal medicine is used to treat diseases and alleviate symptoms, unlike herbal medicine for food.