• Management Science and Financial Engineering
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• v.1 no.1
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• pp.1-19
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• 1995

In this paper, we analyze an M / M / 1 queueing system where there are incentive conflicts among customers. Self-interested customers' decisions whether to join the system or not may not necessarily induce a socially optimal congestion level. As a way to alleviate the over-congestion, toll imposition was used in Naor's paper [3]. Instead of using a toll mechanism, we study the usefulness of imperfect information on system state (queue size, for example) as a way to reduce the over-congestion by self-interested customers. The main conclusion of this paper is that by purposefully giving fuzzy or imperfect information on the current queue size we can improve the congestion in the system. This result might look contradictory to rough intuition since perfect information should give better performance than imperfect information. We show how this idea is verified. In deriving this result, we use the concept of Nash equilibrium (pure and mixed strategy) as introduced in game theory. In some real situations, using imperfect information is easier to apply than imposing a toll, and thus the result of this paper has practical implications.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2001.10a
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• pp.411-415
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• 2001

Advances in computer and sensor technology have made it possible to obtain superlarge manufacturing process data in real time, letting us to extract meaningful information from these superlarge data sets. We propose a systematic data analysis procedure which field engineers can apply easily to manufacture quality products. The procedure consists of data cleaning and data analysis stages. Data cleaning stage is to construct a database suitable for statistical analysis from the original superlarge manufacturing process data. In the data analysis stage, we suggest a graphical easy-to-implement approach to extract practical information from the cleaned database. This study will help manufacturing companies to achieve six sigma quality.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2003.11a
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• pp.71-74
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• 2003

Today, s Businesses can only survive if they can sdapt fast, and this means their IT systems have to adapt too. A challenge for identifying and codifying reengineering expertise is to capture Both aspects of a successful enterprise business architecture(EBA) and suitable description language, with the contexts in which it works. In connected with the state of the art in the field of Web Services architecture and EBA, we propose to exploit the concept of business process execution language(BPEL), one among of description language. In addition, we review current a issue and problem of EAI and Workflow, and outline the main ingredients of a BPEL and EBA for building flexible Web Service. This paper is exploratory study in associated with enterprise architecture(EA) and description language.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2007.11a
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• pp.90-96
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• 2007

In multi-location inventory systems, lost sales due to stockout decreases not only retailers' profit but also whole supply chain's profit. Transshipment between retailers has been considered to be a major solution to the stockout problem, and many supply chains implement transshipment coalition among retailers. However, in practical situations, retailers occasionally refuses to accept the transshipment requests, mainly because they concern the future stockout possibilities of their own. Thus, the objective of this research is to analyze the effect of retailers' interaction under the transshipment coalition environment based on the simulations, and to provide effective policies to promote retailers' transshipment cooperation. Policies using penalty and incentive scheme are proposed, and it is shown that using proposed policies both the retailers' and the headquarter's profit can be increased.

• Journal of the Korean Operations Research and Management Science Society
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• v.38 no.4
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• pp.1-9
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• 2013

We propose a heuristic algorithm for war-game model that is appropriate for warfare in which the maneuver of the attacker is relatively certain. Our model is based on a multi-weapon extention of the Lanchester's square law. However, instead of dealing with the differential equations, we use a multi-period linear approximation which not only facilitates a solution method but also reflects discrete natures of warfare. Then our game model turns out to be a continuous game known to have an ${\varepsilon}$-Nash equilibrium for all ${\varepsilon}{\geq}0$. Therefore, our model approximates an optimal warfare strategies for both players as well as an efficient reinforcement of area defense system that guarantees a peaceful equilibrium. Finally, we report the performance of a practical best-response type heuristic for finding an ${\varepsilon}$-Nash equilibrium for a real-scale problem.

• Journal of Korean Society for Quality Management
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• v.26 no.4
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• pp.265-276
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• 1998

A commercial nuclear power station contains at least two emergency diesel generators(EDG) to control the risk of severe core damage during station blackout accidnets. Therefore, thereliability of the EDG's to start and load-run on demand must be maintained at a sufficiently high level. Until now, a simple assessment of start and load-run success rates was used to calculate the EDG reliability. However, this method has been found to contain many defects. Recently, the work of Martz et al.(1996) proposed the use of the Bayes estimator to find EDG reliability. Shim(1996) proposed a confidence interval for the Bayes estimator, compare the above two methods. In this paper, we introduce the notion of "Composite Reliablility" to estimate the reliability of nuclear-power plant EDG, and using practical examples, illustrate which method is more a, pp.opriate in our situation.situation.

• Journal of Korean Society for Quality Management
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• v.26 no.3
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• pp.141-149
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• 1998

It is of great practical interest to decide when to stop testing a software system in the development phase and transfer it to the user. This decision problemcalled an optimal software release one is discussed to specify the a, pp.opriate release time. In almost all studies, the software reliability models used are nonphomogenous Poisson process(NHPP) model with bounded mean value function. HNPP models with unbounded mean value function are more suitable in practice because of the possibility of introducing new faults when correcting or modifying the software. We discuss optimal software release policies which minimize a total average software cost under the constraint of satisfying a software reliability requirement. A numerical example illustrates the results.

• Journal of Korean Society for Quality Management
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• v.30 no.3
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• pp.186-194
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• 2002

In this paper we introduce formulae for estimating the failure rate of a large scaled software by using the Bayesian rule when a black-box random testing which selects an element(test case) at random with equally likely probability, is performed. A program or software can be treated as a mathematical function with a well-defined (input)domain and range. For a large scaled software, their input domains can be partitioned into multiple subdomains and exhaustive testing is not generally practical. Testing is proceeding with selecting a subdomain, and then picking a test case from within the selected subdomain. Whether or not the proportion of selecting one of the subdomains is assumed probability, we developed the formulae either case by using Bayesian rule with gamma distribution as a prior distribution.

• Journal of Korean Society for Quality Management
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• v.31 no.2
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• pp.143-164
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• 2003

In this paper, we use and apply statistical tools to planning marketing strategy in advanced markets. New comers with low brand awareness in advanced markets can not attain high profit easily and need more effective strategic approach. In this paper, an effective and practical procedure is proposed to plan marketing strategies to satisfy the customer and increase the market share in advanced markets. The procedure consists of 5 steps : market survey, determining target brand, evaluation of brand attributes, gap analysis to determine the goal, and correlation analysis for effective improvement method. A case study is studied in the European market for electric appliances, between a Korean company and other companies. Various statistical tools are used to analyze the phenomena and some important conclusions are derived for effective marketing.

• Journal of Korean Society for Quality Management
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• v.9 no.2
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• pp.44-51
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• 1981

The briquet is made of the coal. The calorie of briquet is 4370 kcal/kg by the law. The combination of coal is important for the manufacturing of briquet. We must know that the Test and Estimation of Calorie is necessary to study. The factory does not make the briquet by the experiment now, but they have made it properly by the experience. We know that the theoritical value of calorie resembles to the practical value of calorie. I think the factory must make a briquet certainly by the experiment. It is a best method for men to prevent from the crisis of briquet gas.