• Journal of Electrical Engineering and Technology
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• v.8 no.4
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• pp.938-944
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• 2013

In this paper, we propose a method for suppressing shaft voltage by modifying the shape of the rotor and the permanent magnets in interior permanent magnet-type-high-voltage motors. Shaft voltage, which is induced by parasitic components and the leakage flux in motor-driven systems, adversely affects their bearings. In order to minimize shaft voltage, we designed a magnet rearrangement and rotor re-structuring of the motor. The shaft voltage suppression effect of the designed model was confirmed experimentally and by comparative finite element analysis.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.05a
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• pp.453-457
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• 2009

Distributed Generation (DG) is predicted to play a important role in electric power system in the near future. insertion of DG system into existing distribution network has great impact on real-time system operation and planning. It is widely accepted that micro turbine generation (MTG) systems are currently attracting lot of attention to meet customers need in the distributed power generation market. In order to investigate the performance of MT generation systems, their efficient modeling is required. This paper presents the modeling and simulation of a MT generation system suitable for isolated operation. The system comprises of a Permanent magnet synchronous generator driven by a MT. A brief description of the overall system is given, and mathematical models for the MT and permanent magnet synchronous generator are presented. Also, the use of power electronics in conditioning the power output of the generating system is demonstrated. Simulation studies with MATLAB/Simulink have been carried out in islanding operation mode of a DG system.

• Proceedings of the Korean Information Science Society Conference
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• 2007.06b
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• pp.228-231
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• 2007

ALBM(Adaptive Load Balancing and Management)은 S/W L4 스위치를 포함하는 능동형 클러스터 시스템이다. 이 클러스터 시스템은 확장 가능한 인터넷 서비스와 적응형 부하분산 처리 능력을 제공한다. ALBM 클러스터 시스템을 설계할 때, 우리는 Model-Driven Development Method를 사용하여 메타모델을 설계하였다. 본 논문에서는 클러스터의 구성을 위한 에이전트관리, 정보관리와 같은 기능과 결함내성을 위한 이벤트관리, 알고리즘관리와 같은 기능을 고려하는 메타모델을 제시한다. 이 메타모델의 초점은 클러스터의 구성관리와 결함관리를 클러스터 관리 시스템의 설계에 반영하여, 새롭게 클러스터 시스템을 설계할 때 쉽게 이러한 기능을 가질 수 있도록 지원하는 것이다.

• Journal of Information Technology Services
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• v.7 no.1
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• pp.131-149
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• 2008

Bandwidth Trading(BT) represents a potential market with over 1 trillion USD across the world and high growth potential. BT is also likely to accelerate globalization of the telecommunications industry and massive restructuring driven by unbundling rush. However, systematic researches on BT remain at an infant stage. This study starts with structure analysis of the Internet industry, and discusses significance of Internet interconnection with respect to BT Issues. We also describe the bandwidth commoditization trends and review technical requirements for effective Internet interconnection with BT capability. Taking a step further, this study explores the possibility of improving efficiency of network providers and increasing user convenience by developing an architectural prototype of Hub-&-Spoke interconnection model required to facilitate BT. The BT market provides an Innovative base to ease rigidity of two-party contract and Increase service efficiency. However, as fair, efficient operation by third party is required, this research finally proposes an exchanging hub named NIBX(New Internet Business eXchange).

• Nuclear Engineering and Technology
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• v.36 no.2
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• pp.153-164
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• 2004

A computational fluid dynamics (CFD) analysis has been performed to investigate the turbulent flow and heat transfer in a triangular rod bundle with pitch-to-diameter ratios (P/D) of 1.06 and 1.12. Anisotropic turbulence models predicted the turbulence-driven secondary flow in a triangular subchannel and the distributions of the time mean velocity and temperature, showing a significantly improved agreement with the measurements from the linear standard $k-{\epsilon}$ model. The anisotropic turbulence models predicted the turbulence structure for a rod bundle with a large P/D fairly well, but could not predict the very high turbulent intensity of the azimuthal velocity observed in the narrow flow region (gap) for a rod bundle with a small P/D.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.6 s.171
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• pp.98-108
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• 2005

Conventional robot manipulators actuated by motors with the speed reducer such as the harmonic drive have weakness in the load capacity, since the speed reducer does not have enough strength. To improve this, a new type of robot actuator based on the four-bar-link mechanism driven by the ball screw was constructed. Also, a new type of revolute robot manipulator composed of the developed actuators was developed. But, modelling errors occur due to the off-set from the nominal model since the exact modeling of the complex inertia variation of the four-bar-link actuator is very difficult. To control the proposed robot along the prescribed trajectory, a sliding mode control algorithm was applied with compensation function for the modeling errors. To show performance of the proposed controller, a computer simulation was performed, and its results was presented.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.3
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• pp.89-96
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• 2003

An electro-hydraulic manipulator using hydraulic actuators has many nonlinear abetments, and its parameter fluctuations are greater than those of an electrically driven manipulator. So it is relatively difficult to realize not only stable but also accurate trajectory control for the autonomous assembly tasks using hydraulic manipulators. In this report, we propose a two-degree-of-freedom control including parallel feedforward compensator (PFC) where PFC plays a very important role in the stability of a proposed control system. In the experimental results of the 6-link electro hydraulic manipulator, it is verified that the stability and the model matching performance are improved by using the proposed control method.

• Asia pacific journal of information systems
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• v.25 no.1
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• pp.25-60
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• 2015

Use cases are commonly used to represent customer requirements during systems development. In a large software development environment, finding relevant use cases from a library of past or related projects is a complex, error-prone and expensive task. This study proposes an ontological methodology to support use case retrieval in an interactive manner. The architecture of a prototype system that implements this methodology is presented. To evaluate whether the proposed approach can provide satisfactory results to users, this study develops a research model and hypotheses based on interaction theory. These hypotheses are empirically tested using a laboratory experiment which controls information filtering and perceived interaction. Our study suggests that a system which interacts with a user intelligently reduces cognitive load and increases self-efficacy and satisfaction.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 1997.11a
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• pp.327-334
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• 1997

In many large urban-fire scenarios one of the critical issues is to attempt to protect the lives of fire fighters in helicopters deployed to flying over the fires and also the lives of people trapped in open areas downwind of the fires such as in parks. The strategies of such protection measures depend significantly on our knowledge of the size and extent of such fires as affected by the prevailing winds. In this study, the shape or profile of the fire plume typical of large urban fires, as affected by a steady unidirectional wind with or without imposing a shear flow on the fire plume, has been simulated numerically by a field model. The results show that the simulations provide realistic flame profiles and at least qualitatively, the same flame dynamics when compared to those from the experiments, and that the fire plumes are sensitive to small variations in the asymmetry of the wind shears, including the appearance of swirling flames within the fire plumes.

• 한국IT서비스학회:학술대회논문집
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• 2006.11a
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• pp.185-189
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• 2006

기존의 레거시 시스템은 개발과정에 있어서 이미 많은 시간과 경험과 지식을 갖고 있기 때문에 조직의 핵심 가치를 지닌 재사용 자산으로 활용할 수 있는 의미있는 자산이다. 그러므로 레거시 시스템에서 사용해 왔던 가치있는 자산들을 웹을 기반으로 한 e-비즈니스 환경에 적용시키고, 다양한 플랫폼에서 사용하기 위한 필요성이 증대되었다. 변화하는 환경에 따라 레거시 시스템을 현대화(Modernization)하는 방법중의 하나로 현재 시스템에서 운용되고 있는 것을 OMG에서 제안한 모델기반아키텍처(MDA)를 사용하여 여러 플랫폼을 쉽게 지원하고 모델기반의 통합을 하고자 한다. MDA 환경을 기반으로 기존의 레거시 시스템을 활용하기 위하여 기존의 소프트웨어를 직접 수정 없이 재사용하거나 PSM에서 PIM 변환을 하기 위하여 래퍼(wrapper를 사용한다. 본 논문에서는 이러한 래퍼의 사용에 따른 문제점을 분석하고, 요구에 따라 모델에 대한 접근방식을 다르게 사용하여 시스템의 개선상황에 유연하게 대처할 수 있도록 래퍼를 상황에 따라 적절하게 사용하는 혼합(hybrid) 방식을 적용한 개선전략을 제안하고자 한다.