• Journal of the military operations research society of Korea
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• v.18 no.2
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• pp.181-191
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• 1992

In this paper in order to prevent break of operation of equipments resulted from the delay of parts supply, the continuous review(Q, r) inventory model with probabilistic lead time is developed. If the lead tire is random varivable, the cycle also is stochastic. Then it is not easy to obtain the total cost equation of this inventory model. Therefore it is assumed that one cycle is the interval of reorder points. When the lead time is assumed to have exponential probability distribution, the lot-size and reorder point which minimize total cost are obtained. And as the lead time increases, the order quantity and the total cost are greater, but the reorder point increases by a certain point of time and then decreases.

• Journal of the military operations research society of Korea
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• v.31 no.2
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• pp.45-59
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• 2005

As more advanced and complicated equipments are introduced, effective operation and maintenance, along with acquisition of the equipments, commands more significance lately. In order to perform effective depot maintenance, the Republic of Korea Army is continually developing the concept, cycle and method for operating the depot maintenance. Not only the high-cost testing and maintenance equipments but the highly developed maintenance technologies are required for the depot maintenance of the latest weapon system. In order to have the depot maintenance capability, this paper provides the standard and procedure for estimating the development cost of the depot maintenance elements to be utilized in the depot maintenance elements development project.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2001.10a
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• pp.322-325
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• 2001

This paper is focused on the development of the DFX system which can support the task that designer or project teams analyse and evaluate the feasibility of the product concept quickly, and then improve the problem of the product and process design before the manufacture in the M-T-O (make-to-order) environments. In this paper, we importantly treated three points for the effective development of the DFX system. The first, we proposed the procedure and architecture of the DFX system which fit with the M-T-O environments. The second, we designed and implemented the DFX prototype system on the WWW, in order to allow the multi-accessing and multi-processing regardless of time and position. The last, we described the benefits of the Web-based DFX system.

• Journal of the Korean Operations Research and Management Science Society
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• v.30 no.2
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• pp.63-71
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• 2005

In the field of nuclear reactor safety study, common cause failures (CCFs) became significant contributors to system failure probability and core damage frequency in most Probabilistic risk assessments. However, it is hard to estimate the reliability of such a system, because of the dependency of components caused by CCFs. In order to analyze the system, we propose an analytic method that can find the parameters with lack of raw data. This study adopts the shock model in which the failure probability increases as the shock is cumulated. We use two-step Expectation and Maximization (EM) algorithm to find the unknown parameters. In order to verify the analysis result, we perform the simulation under same environment. This approach might be helpful to build the defensive strategy for the CCFs.

• Journal of the Korean Operations Research and Management Science Society
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• v.12 no.1
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• pp.1-9
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• 1987

This paper considers (S -1, S) inventory models which have wide applications in reparable spare parts inventory systems and multi-echelon systems. We assume a discrete compounds Poisson demand and order size dependent delivery times ; when the replenishment order size is n, we assume the delivery time distribution is arbitrary with finite mean $b_{n}$ . On the basis of the fact the outstanding orders follow a certain queueing process, we introduce the results of Fakinos (1982). We develop the efficient recursive formulae to find the optimal $S^{*}$ under several performance measures as a function of the decision variable S. The results of this paper can be applied to the multi-echelon systems such as MEETRIC.C.

• Journal of the Korean Operations Research and Management Science Society
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• v.36 no.4
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• pp.29-41
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• 2011

As industires are evolving into a more advanced type industrial system, service economy has been more emphasized. But with the expansion of the service economy, the failure of the service has also increased. Customers flee caused by the service failure leads to from simple problems like financial loss to serious problems like damaging corporate image. Therefore, if possible, the system providing defect-free service should be established. If this is not possible, preventive measures should be taken in order to minimize the failure. The study as a tool to prevent service failure presents the concepts "service error matrix." And to confirm whether this idea is practical or not, this study investigated the hotel, one of the leading service industries, about actually occurring service failure and applied to service error matrix suggested in this study. Finally service blueprint and Poka-yoke are completed in order to reduce service failure of Y hotel which was the object of the interview for this study.

• Journal of the Korean Operations Research and Management Science Society
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• v.14 no.1
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• pp.53-53
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• 1989

Generally, the standard sizes of military combat fatigues should be determined by considering the coverage rate in order to minimize the military personnel who can't put on the ready made military combat fatigues. The coverage rate should be increased by the longer interval of the standard size but the satisfactory rate will be decreased due to the longer interval of size. This study develops a method selecting optimal standard sizes of the military combat fatigues in order to maximize the satisfactory rate that insures the coverage rate to meet a given level for ready made military combat fatigues. This method selects candidate standard sizes at second and finally, establishes a 0-1 integer programming model. The result shows that the method increases both coverage and satisfactory rate more than those of the previous method.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1994.04a
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• pp.527-534
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• 1994

This paper presents a Bin-Picking method in which robot recognizes the positions and orientations of unoccluded objects at the top of jumbled objects placed in a bin, and picks up the unoccluded objects one by one from the jumble. A method using feasible region, painting, and hierarchical test is introduced for recognizing the unoccluded objects from the jumbled objects. The 3D information is obtained using the bipartite-matching method which finds the least difference of 3D by comparing vertexes of one camera with vertexes of the other camera, then hypothesis and test are done. The working order of unoccluded objects is made based on 3D, position, and orientation information. The robot picks up the unoccluded objects from the jumbled objects according to the working order. This all process continues to the empty bin.

• Journal of the Korean Operations Research and Management Science Society
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• v.4 no.1
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• pp.51-67
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• 1979

This paper considers the problem of determining an optimal dynamic operating policy for a two-stage tandem queueing service system in which the service facilities (or stages) can be operated at more than one service rate. At each period of the system's operation, the system manager must specify which of the available service rates is to be employed at each stage. The cost structure includes an operating cost for running each stage and a service facility profit earned when a service completion occurs at Stage 2. We assume that the system has a finite waiting capacity in front of each station and each customer requires two services which must be done in sequence, that is, customers must pass through Stage 1 and Stage 2 in that order. Processing must be in the order of arrival at each station. The objective is to minimize the total discounted expected cost in a two-stage tandem queueing service system, which we formulate as a Discrete-Time Markov Decision Process. We present analytical and numerical results that specify the form of the optimal dynamic operating policy for a two-stage tandem queueing service system.

• Korean Journal of Clinical Laboratory Science
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• v.36 no.2
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• pp.153-157
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• 2004

The aim of our study is to determine maximum surgical blood order schedule (MSBOS) in each surgical operation through analyzing usage of blood products at Bundang Jesaeng General Hospital. We investigated the amount of transfused red cells for each operation and calculated crossmatching-to-transfusion ratio (C/T ratio) and MSBOS. This was accomplished by referring to the Laboratory Information System program during 1 year from January through December 2003. Coronary artery bypass surgery and decompressive craniectomy showed the highest MSBOS in our hospital. The average C/T ratio was 3.2 and excessive reservations for blood products have been made for many operations. From this study, guidelines for the optimal blood ordering for each surgery were suggested.