• Journal of The Korean Society of Agricultural Engineers
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• v.55 no.3
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• pp.1-7
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• 2013

The dam plan quantity of constructive and water supply quantity of present time are showing a difference with change in climate and augmentation of water demand for multipurpose dams in Nakdong river basin. But revaluates a water supply ability the method or the process is official for is not taking a position, so actual condition applies the plan quantity of dam constructive. Considers various situation of actual multipurpose dam from research sees consequently and in K-WEAP is an integrated water resources evaluation plan model applies as water permit availability multipurpose dam, currently water permit availability comparison, analyzed. In this study, the natural daily flow data and apply the dimensions of the reservoir, and for more than 30 years of the long-term water balance analysis conducted by Date Nakdong river basin can supply reservoirs are large quantity of permits available is presented.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.12
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• pp.532-539
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• 2005

The demand of Gas Insulated Transformer(GIT) using $SF_6$ gas as insulating and cooling medium is being increased dramatically in the underground substation of urban area because it has the advantages of non-flammable and non-explosive, etc. This paper describes the structural features and advantages of the gas insulated transformer compare to an oil immersed transformer, and presents a brief overview of the consideration and technology which apply to $SF_6$ gas insulated transformer.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2002.05a
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• pp.378-384
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• 2002

In this paper, we propose a mixed integer optimization approach for solving the inventory problem with variable lead time, reorder point, crashing cost and price -quantity discount. Chang and Chang[15] study a continuous review inventory model in which lead time is a decision variable under price-quantity discount. However, their study cannot find the optimal solution due to the flaws in the modeling and the solution procedure. We present a complete procedure to find the optimal solution for the model. In addition to the above contribution, we also apply the minimax distribution free approach to the model to devise a practical procedure which can be used without specific information on demand distribution.

• Journal of the Korea Society for Simulation
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• v.8 no.1
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• pp.63-76
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• 1999

Recently in manufacturing environment, manufacturing order is characterized by unstable market demand, shorter product life cycle, a variety of product and shorter production lead time. In order to adapt this manufacturing order, flexible manufacturing systems(FMS) in manufacturing technology advances into the direction that machines become further versatile functionally and that tools are controlled by fast tool delivery device. Unlike conventional FMS to mainly focus on part flow, it is important to control tool flow in single-stage multimachine systems(SSMS), consisting of versatile machines and fast tool delivery device. This research is motivated by the thought that exact estimation of tool competition at part release in SSMS enhances the system performance. In this paper, in SSMS under dynamic tool allocation strategy to share tools among machines, we propose real-time part release and tool allocation algorithms which can apply real factory and which can improve system performance.

• Proceedings of the Korea Society for Simulation Conference
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• 1999.04a
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• pp.60-64
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• 1999

Recently in manufacturing environment, manufacturing order is characterized by unstable market demand, shorter product life cycle, a variety of product and shorter production lead time. In order to adapt this manufacturing order, flexible manufacturing system(FMS) in manufacturing technology advances into the direction that machines become further versatile functionally and that tools are controlled by fast tool delivery device. Unlike conventional FMS to mainly focus on part flow, it is important to control tool flow in single-stage multimachine systems(SSMS), consisting of versatile machines and fast tool delivery device. In this paper, in SSMS under dynamic tool allocation strategy to share tools among machines, we propose real-time part release and tool allocation algorithms which can apply real factory and which can improve system performance.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.4
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• pp.344-352
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• 2005

The modem production systems are required to produce many items. This is due to the fact that society has become more complex and the customers' demands have become more varied. The demand for complex production systems of various purposes, which can flexibly change the content of work, has increased. One of such production systems is FMS (Flexible Manufacturing System). Limited resources must be used in FMS when a number of working procedures are simultaneously being undertaken because the conditions of stand-by job processes cannot be changed. Researchers are currently being conducted to determine ways of preventing deadlocks. In this study, we proposes the algorithm for detection and recovery of a deadlock status using the DDAPN(Deadlock Detection Avoidance Petri Net). Also, we apply the proposed algorithm has a feature to the FMS.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.5
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• pp.1007-1017
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• 1997

The existing survivability measure is defined as the only ratio of survival traffic volume on the given traffic demand. In this paper we suggest a new network survivability evaluation model. Sinceit depends on the importance of traffic, we can evaluatethe affect of telecommunication disaster. With the suggested evaluation model we formulate optimization models for restoration paths and traffic assinment on them. The optimization models are represented as mixed integer programming problems, which are difficult to find exact solutions. We develop heuristic algorithms according to the optimization models and apply them to an example network with 10 nodes and 17 links.

• Journal of Advanced Engineering and Technology
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• v.10 no.2
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• pp.203-208
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• 2017

Due to global climate change issues, there is a growing demand for systems throughout the industry. In the case of power conversion, studies have been actively conducted to change the structure of the power conversion circuit and to apply new power devices. In particular, the WBG (Wide Band Gap), which is newly emerged device in the market for developing semiconductor technology, has demonstrated advantages in applying for various aspects in comparison to the existing Si (Silicon) Semiconductor. Recent research centers in the railway industry are focusing on developing technologies suitable for railway vehicles by utilizing these new developments in railway countries such as Japan and Europe. This paper researches the WBG device that is applicable to the auxiliary power supplies (APS) in railway system, and analyzes the downsizing effects to APS in high-speed railway by conducting a theoretical analysis and simulation.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.123-126
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• 1998

Generally, in a VOD(video on Demand) system, batching technique is oten used to improve throughput. Since subscribers to VOD servives tend to withdraw their requests as the latency becomes large, an optimal scheduling scheme should consider not only batching size but also withdrawal rae, service latency and fairness between different programs. In this paper, we propose a new scheduling scheme, which shows improvement in fairness and reduction in withdrawal rate and service latency compared with other well known schemes. When there are 2 or more streams are available in the VOD server, proposed scheme apply different program selection policies to each streams. Using this approach effectiveness of stream usage can be improved.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.38-41
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• 1998

Due to the increasing demand to multimedia services over wireless communication network, LMDS(Local Multipoint Distribution Service) has been proposed as an alternate approach for broadband wireless access network. But LMDS, Which uses the mmwavelength radio spectrum, has been limited for unknown microwave frequency characteristics. In this paper, we analyze the parameters related to the system design on 28GHz frequency: Propagation path loss and rainfall attenuation. Based on these analytical results, the proper cell size in Korea is determined. We also analyze the bit error rate and frame loss rate for various kinds of digital modulation schemes(QAM 4, 16, 64, 256). Finally, we apply to ㅍ service to evaluate a call blocking rate, efficiency and channel capacity.