• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.9
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• pp.81-86
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• 2007

Electric utility companies have the responsibility of providing good electricity for their customers. They have introduced the DAS(Distribution Automation System) to automate the power distribution networks. DAS engineers require state-of-the-art applications, such as a way to actively manage the distribution system and gain economic benefits from a flexible DAS architectural design. The existing DAS is not capable of handling these needs. It requires operator intervention whenever feeder overloading is detected while operator error could cause the feeder overload area to be extended. It also utilizes a closed architecture and it is therefore difficult to meet the system migration and future enhancement requirements. This paper represents a web based, platform-independent, flexible DAS architectural design and active database application. Recent advanced Internet technologies are fully utilized in this new DAS architecture allowing it to meet the system migration and future enhancement requirements. By using an active database, the DAS can minimize the feeder overloading area in the distribution system without operator intervention, thereby minimizing mistakes due to operator error.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.172-175
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• 2007

The Performance of a PEMFC stack is strongly dependent on the uniform reactants distribution on MEA. The uniform distribution can be achieved by flow-field pattern and manifold design optimized to satisfy operating conditions. This paper investigates uniform reactants distribution in channels by changing manifold shape and inlet mass flow rate. Typical U and Z shape and modified U and Z shape manifolds with buffer zone were designed. To check the uniform reactants distribution, standard deviation of mass flow rate was compared. The numerical results show that the inlet mass flow rate, inlet shape, and manifolds shape are critical factor for uniform distribution.

• Water Engineering Research
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• v.2 no.3
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• pp.171-178
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• 2001

There are three methods for analyzing flow and pressure distribution in looped water distribution networks (the loop method, the node method, the element method) taking into consideration hydraulic parameters chosen as unknown. For all these methods the non-linear system of equations can be solved by iterative procedures. The paper presents a different approach to this problem by using the method of variational formulations for hydraulic analysis of water distribution networks. This method has the advantage that it uses a specialized optimization algorithm which minimizes directly an objective multivariable function without constraints, implemented in a computer program. The paper compares developed method to the classic Hardy-Cross method. This shows the good performance of the new method.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.6
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• pp.47-52
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• 2012

DAS(Distribution Automation System) is equipped with several software applications such as service restoration, loss minimization, and protective relay coordination. The software applications of DAS are very sensitive to the amount of section load being carried by a particular section of distribution lines. Moreover, each software application requires a different parameter of the section load according to its purpose. Therefore, This paper proposes a new section load management method using real-time measurement data of the distribution lines. In order to provide accurate data to DAS applications, this method considers section loads in terms of the relationship of power versus time. In order to establish that the proposed method is feasible, a performance-testing simulator was developed, and case studies were conducted for a modified real distribution network.

• Journal of The Korean Society of Agricultural Engineers
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• v.56 no.1
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• pp.11-20
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• 2014

Many classification studies for the community of densely-connected nodes are limited to the comprehensive analysis for detecting the communities in probabilistic networks with nodes and edge of the probabilistic distribution because of the difficulties of the probabilistic operation. This study aims to use convolution method for operating nodes and edge of probabilistic distribution. For the probabilistic hierarchy network with nodes and edges of the probabilistic distribution, the model of this study detects the communities of nodes to make the new probabilistic distribution with two distribution. The results of our model was verified through comparing with Monte-carlo Simulation and other community-detecting methods.

• Journal of Distribution Research
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• v.2 no.1
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• pp.59-85
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• 1997

The automobile industry in Korea has grown to the fifth in the world in terms of production capacity. In spite of the production growth, the marketing aspects such as distribution and customer service in the auto industry are still behind the world-class. Thus, the major purposes of this paper are as follows. The first is to analyze competitive structure of the industry and to compare distribution strategies of the major auto firms(Hyundai, Daewoo, and Kia). The second is to theoretically explain the transition from the vertical marketing system to the dealer system using transaction cost analysis. The third is to compare auto distribution channels in Korea with those in the U.S. and Japan. Finally, an optimal channel stucture in the auto industry is suggested after reviewing five alternative channel structures such as corporate-owned VMS, sales-specializing firm, multiplex system(VMS+limited dealer system), dual sales channel, and advanced dealer system. In the short-run, sales-specilizing firm was suggested as an optimal channel system to enhance customer satisfaction by integrating sales and customer service. In the long-run, advanced dealer system through regional differentiation was desirable for an optimal channel structure by organically integrating new car sales, used car sales, and after service to provide total marketing service to customers.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.6
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• pp.692-698
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• 1999

This paper analyzes the effect of DGS(Dispersed Generation System) on the voltage regulation of the traditional distribution system of which the voltage is controlled by the bank LDC(Line Drop Compensator). Through the simulation results for 22.9kV class distribution system with DGSs, some general relationships among the operating power factor and introduction limit of DGS, and the sending-end reference voltage determined by internal setting coefficients of the LDC are derived. Those relationships are that the introduction limit of DGS increases as the power factor of DGS goes from lagging to leading and also as the allowance of the sending-end reference voltage increases. From the relationships, a operation method of the power distribution system integrated with DGSs is proposed from the view point of the operating power factor of DGS and new voltage regulation method.

• Proceedings of the KIEE Conference
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• 2001.05a
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• pp.155-158
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• 2001

The objective of this study is to evaluate properly reliability of underground distribution system taking into account domestic circumstance. Interruption time and number of interruption customer by distribution system based on actual condition in domestic utility are considered as important index to estimate reliability of underground distribution system. This paper presents evaluation results regarding the reliability of an underground distribution system using a model system as new urban area, evaluation results which is established whether automatic system is introduced or not are shown in detail.

• Journal of Korean Society for Quality Management
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• v.25 no.1
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• pp.182-192
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• 1997

The well-known standard normal distribution has been used within the limit of standard variable value of u=3.59. However, the probability values above the limit are not given in the literature. In this study, a probability computation program for standard normal distribution to u=5.99 with the proportional normal distribution a, pp.oximation suggested by Abramowitz and Stegun, Hastings is developed. The new standard normal distribution table developed by the program is presented and will be of help to estimate of probability values for testing and estimation of process mean value, lot acceptable probability, defective percentage of PPM unit of an out-of specification limit, process capability, test power of control charts, probability and statistics.

• Journal of Korean Society of Transportation
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• v.5 no.1
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• pp.47-58
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• 1987

A commodity distribution problem with intertemporal storage facilities and dynamic transportation networks is proposed. mathematical integer programming methods and multiobjective programming techniques are used in the model formulation. Dynamic characteristics of commodity distribution problems are taken into account in the model formulation. storage facility location problems and transportation link addition problems are incorporated into the intertemporal multicommodity distribution problem. The model is capable of generating the most efficient and rational commodity distribution system. Therefore it can be utilized to provided the most effective investment plan for the transportation infrastructure development as well as to evaluate the existing commodity distribution system. The model determines simultaneously the most efficient locations, sizes, and activity levels of storage facilities as well as new highway links. It is extended to multiobjective planning situations for the purpose of generating alternative investment plans in accordance to planning situations. sine the investment in transportation network improvement yields w\several external benefits for a regional economy, the induced benefit maximization objective is incorporated into the cost minimization objective. The multiobjective model generates explicitly the trade-off between cost savings and induced benefits of the investment in transportation network improvement.