• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.4
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• pp.124-130
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• 2004

In this paper, we developed DSP(Digital Signal Processor)-based control system to automatically open and close passive filter, which is used to reduce harmonics, according to operating condition of loads. Passive filter control system automatically open and close each branch of filter according to working conditions of loads by sending signals to open and close installation of passive filter after measuring and monitoring voltage, current, harmonics, reactive power, power factor and so on. We verified it's performance by connecting control system with passive filter in the power line using the 100HP D.C motor drive, opening and closing passive filter according to operation condition of motor, and measuring harmonics and reactive power, etc.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.8
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• pp.1700-1704
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• 2004

In this paper a novel power converter for some notches generation in the point of common coupling is described. The magnitude, width, polarity, and position of the notches generated by the proposed scheme can be varied arbitrary with simple control. The scheme has good features of simple structure, high reliability, low cost, high efficiency, and the capability of arbitrary several notches generation. The converter can be used for the test of custom power devices such as UPS, DVR, active power filter, etc. The circuit operation is described and the usefulness of the scheme is verified through simulations.

• The Transactions of the Korean Institute of Power Electronics
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• v.5 no.1
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• pp.88-94
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• 2000

In this paper, a parameter estimation method for a vector control of induction motors is presented. It can be easily implemented to the inverters in the industrial fields such as continuous process line, which requires the high performance of torque control, because of being estimated under the condition of the actual operating states. Also, this method nems no additional hardware such as voltage sensors and measuring equipments by the estimation of output voltage, and has good accuracy and repeatability by observing the variation of the stator voltage due to estimation errors. Experimental results verify the validity and usefulness of the proposed estimation method in the industrial fields.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.8
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• pp.678-685
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• 2017

The radiator of the data storage and handling units onboard the earth observation satellite is a groove-type radiator covered with a shield because of the periodic high heat dissipation and design characteristics of arrangement and mountability of the unit. The effect of the groove-type radiator and that of the shield versus plane radiator were verified through the thermal vacuum test. Through the test result, the temperatures of the radiator and the heat exchange due to the view factor were analyzed by using the analytical method. Conclusively the thermal performance of the shield dissipation plate was verified.

• Journal of the Korea Society of Computer and Information
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• v.10 no.5 s.37
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• pp.199-208
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• 2005

In this thesis, we have proposed an extended resource management mechanism that optimizes the QoS of multimedia service by complementing the existing resource management mechanism used in IP networks. The proposed resource management mechanism is composed of traffic Scheduler which was designed based on statistic analysis of the distribution of user traffic occurrence, Traffic Monitor Unit, Bandwidth Allocation Unit, queue Controller, and Traffic Classifier In order to confirm the validity of the proposed resource management mechanism, its performance was analyzed by using computer simulation. As a result of performance analysis, its availability was proved.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.178-181
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• 2011

본 연구에서는 광섬유센서를 내장한 스마트강연선을 이용하여 초고성능콘트리트로 제작된 하이브리드 사장교 세그먼트의 횡방향 도입 긴장력을 계측하고 세그먼트 내부의 프리스트레스를 계측하여 즉시손실에 해당하는 정착장치 활동에 의한 손실과 마찰손실을 도로교설계기준(2005)의 설계 마찰손실과 비교하였다. 제작된 2개의 UHPC 사장교 세그먼트는 횡방향 길이 16.7m, 종방향 길이 1.75m, 높이 1.5m이며 각 시험체의 1/4, 1/2, 3/4지점에 긴장력을 계측하기 위해 3개의 FBG센서를 배치하였다. 긴장력은 유압잭을 이용하여 5개의 강연선에 동시에 순차적으로 도입되었으며, 단부에서 최대 도입 긴장력은 세그먼트 1은 734kN, 세그먼트 2는 639kN이었다. 도로교설계기준에 제시된 마찰계수의 중간값(파상마찰계수=0.00405, 곡률마찰계수=0.20)을 사용하여 FBG센서 위치에서 계산된 긴장력은 계측치와 5% 이내의 차이를 보였으며, 정착장치 활동에 의한 순간손실은 긴장단에서 최대 12.8%로 계측되었다. 이로부터 이 연구에서 제시하는 긴장력계측방법의 적용성을 입증할 수 있었으며, 향후 이 방법은 프리스트레스트 콘크리트 교량의 설계기준 마찰계수 개정을 위한 연구에 좋은 도구로 활용될 수 있을 것으로 기대된다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.1C
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• pp.94-101
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• 2008

In this paper, we introduce a real-time state-of-polarization(SOP) finding system. The system divides the optical wave into linear horizontal- and vertical-SOP components and measures two different beat-signals, which are produced by superposition with reference optical source, in time domain. From these measured beat signals we can get SOP information of the signal instantly. Since the proposed scheme is a feed-forward measurement system, comparing with conventional systems which require an optical feedback loop, the measurement time becomes reduced tremendously. We also introduced a novel calibration method for compensating birefringence-related errors which may occur during the measurement. We prove the operation and performance of the proposed system through computer simulation and actual experiments.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.10B
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• pp.857-865
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• 2006

In order to test and evaluate the various functions and services of NGN would be promised, a specified methodology is needed and a development for the identification of testing object, configuration and test traffic are required. Simulation and analytical modeling methodshave used for IP performance testing, but further study issue still remains. This paper proposes new evaluation methodology to achieve an objective approach rather than a subjective and isolated, based on the real-field environment, for NGN network. For this purpose, background traffic pattern to interfere test traffic was specified and it was tested in actual NGN testbed with systems having NGN technology, such as per bandwidth and packet size. The results shows the suggested methodology is appropriate, comparing with parameters which are Delay, Jitter and Loss the current approach for the end-to-end performance evaluation on NGN.

• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.6
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• pp.467-473
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• 2001

BMS(Battery Management System) in EV system(Electric Vehicle) senses voltage, temperature and the charging or discharging current of batteries. The main roles of BMS are to estimate SOC(State OF Charge) of batteries and optimally monitor them according to the operation state of EV system which is motoring mode or charging mode. In this paper, we propose the proper algorithm about BMS's roles and operation which is suitable to EV system and illustrate validity and effectiveness through the experiments which were performed in the condition of Vehicle road test and charging test.

• Proceedings of the Korean Information Science Society Conference
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• 2010.06b
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• pp.216-221
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• 2010

초기 전자악기를 만드는 사람들은 자신들이 직접 만든 터치 장치를 사운드 조절에 이용하였다. 1982년에 첫 멀티터치 시스템이 개발되었고 21세기 초까지 많은 연구와 멀티터치 시스템의 성능 향상에도 불구하고 대중화의 길은 요원해 보였다. 그러나 2007년 애플의 아이폰을 시작으로 멀티터치 인터페이스는 큰 인기를 끌게 되었고 스마트폰을 통해서 대중들이 멀티터치 인터페이스의 특징을 보다 쉽게 체험 할 수 있게 되었다. 이러한 흐름 속에서 멀티터치 인터페이스는 자연스럽게 사람들의 주목을 받으며 다양한 가능성을 보이고 있지만 관련 콘텐츠의 부재와 개발 인프라의 부족으로 인해 대중화의 길로 다가서기에는 여전히 부족한 현실이다. 본 논문에서는 현재의 멀티터치 인터페이스의 문제점을 지적하고 멀티터치 인터페이스 시장의 활성화와 멀티 터치 관련 콘텐츠 제작자를 위한 범용 멀티터치 인터랙션 시스템을 제안한다. 실험을 통해 제안한 시스템의 효율성을 입증하고 나아가 멀티터치 콘텐츠 시장이 발전할 수 있는 방안을 제시한다.