• Journal of the Korean Society for information Management
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• v.4 no.2
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• pp.62-83
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• 1987

This paper reports investigation of informal communication among Korean biological scientists. Scientists at the research front communicate informally each other and social organization based upon this communication relation is identified. Seventy-four percent of the scientists are joined together in a large communication network which includes all of the most productive and communicative scientists. Central scientists are the nodal points for dissemination of information as well as important information sources.

• Journal of Korea Foundry Society
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• v.11 no.1
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• pp.79-84
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• 1991

The process of solidification of metal is accompanied by liquid-solid change and known as Stefan's heat conduction problem on the moving boundary. In this study the temperature distribution in ingot and metallic mould during casting was analyzed by the two dimensional heat conduction theory. The transient temperature distribution was numerically calculated using a finite element method on the nodal point of mesh screen representing ingot and mould cross section. The theory was applied on the casting of aluminum(purity ; 99%) in flat ingot mould of GC25. The analysis will make it possible to calculate an optimum mould shape of which temperature gradient becomes minimum.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.7A
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• pp.451-466
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• 2003

Untethered nodes in mobile ad-hoc networks strongly depend on the efficient use of their batteries. In this paper, we propose a new metric, the drain rate, to forecast the lifetime of nodes according to current traffic conditions. This metric is combined with the value of the remaining battery capacity to determine which nodes can be part of an active route. We describe new route selection mechanisms for MANET routing protocols, which we call the Minimum Drain Rate (MDR) and the Conditional Minimum Drain Rate (CMDR). MDR extends nodal battery life and the duration of paths, while CMDR also minimizes the total transmission power consumed per packet. Using the ns-2 simulator and the dynamic source routing (DSR) protocol, we compare MDR and CMDR against prior proposals for power-aware routing and show that using the drain rate for power-aware route selection offers superior performance results.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.1251-1253
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• 2001

This paper presents on capacity design of DC-fed-traction system. The system is introduced including a characteristics of train, feeding network configuration, and design method of substation arrangements. Optimal design procedures is described, and program for capacity computation of the system is presented using the nodal equation, K.C.L, K.V.L, Ohm's law and superposition theory. For the proof of the proposed algorithm, we accomplished the simulation of DC traction system for HA-Nam LRT. By considering whole component in DC traction system the conclusion will be much precise.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.474-476
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• 2000

Because of the continuous growth of energy consumption, and also the tendency to site power lines and pipelines along the same route, the close proximity of power lines and metallic pipelines has become more and more frequent. Therefore, there has been and still is a growing concern about possible hazards resulting from the influence of power lines on metallic pipelines. This paper calculates the induced voltage of the pipeline which has the same right-of-war with 154kV and 22.9kV power cables in a tunnel. And propose the best phase order to minimize the induced voltage.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.855-857
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• 2005

Transmission congestion is one of the Key factor to local market power in competitive electricity markets. Financial transmission rights provide the financial protection to their holders by paying back the congestion cost. However, the market participants who have market power can exacerbate their market power. This paper analyzes the effect of exercising local market power with the rights on the market price. The proposed methodology was demonstrated with the Optimal Power Flow(OPF). Case study is fulfilled by GAMS simulation. The simulation are condusted in case of Nodal Pricing.

• Proceedings of the KIEE Conference
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• 2005.11b
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• pp.207-210
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• 2005

The Similarity Index[1] is a good Performance measure for the network reduction. It can be applied to the network reduction In the zone categorized by the nodal prices. This paper deals with a zonal reduction method based on the similarity indices. The proposed method was verified by IEEE 39 bus test system.

• Proceedings of the Korea Society for Simulation Conference
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• 2001.10a
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• pp.373-379
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• 2001

There is a big issue to generate 3D hexahedral finite element (FE) model, since a process to divide the whole domain into several simple-shaped sub-domains is required before generating a continuous mesh with mapped mesh generators. In general, it is nearly impossible to set up proper division numbers interactively to keep mesh connectivity between sub-domains on a complicated arbitrary-shaped domain. If mesh continuity between sub-domains is not required in an analysis, this complicated process can be omitted. Element-free Galerkin method (EFGM) can accept discontinuous meshes, which only requires nodal information. However it is difficult to choose a reasonable influenced domain in moving least squares scheme with non-uniformly distributed nodes in discontinuous FE models. A new FE scheme fur discontinuous mesh is proposed in this paper by applying improved EFGM with some modification to derive FE approximated function in discontinuous parts. Its validity is evaluated on linear elastic problems.

• Korean Journal of Bronchoesophagology
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• v.16 no.1
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• pp.5-10
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• 2010

Objectives The purpose of this article was to review the video-assisted mediastinoscopic surgery (VAM) as diagnostic or therapeutic tools. Summary The VAM was indicated in diagnosis of pleural diseases, dissection or sampling of mediastinal or paraesophageal lymph nodes, nodal staging in lung cancer, or various therapeutic approaches. The advantages of VAM were included that was less painful, cosmetic merit, no need additional drain, and no effect of cardiopulmonary function. It was provided to surgeons wider and more detail operational field rather than conventional mediastinoscopic surgery. It was useful tool as training beginner surgeon, Although the VAM had limited indications, it would be feasible and important multi-purposal operational tools in mediastinal, pleural and lung diseases.

• Korean Journal of Computational Design and Engineering
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• v.11 no.2
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• pp.138-147
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• 2006

A systematic approach to tetrahedral element or mesh generation, based on an advancing-front method and an optimal triangular mesh generation technique on the surface, is presented in this paper. The possible internal nodes are obtained by the octree-decomposition scheme. The initial tetrahedral mesh system is constructed by the advancing-front method and then it is improved by the quality improvement processes including mesh swapping and nodal smoothing. The approach is evaluated by investigating the normalized length, the normalized volume, the dihedral angle and the normalized quality