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이재조,유정훈,홍충선,이대영 대한전기학회 2004 전기학회논문지 D Vol.53 No.5(D)
Currently, high data rate PLC(Power Line Communications), up to 100 Mbps, which use frequency bandwidth between 2 MHz and 30 MHz is investigated very hard, and commercial PLC modem for low voltage powerline network (indoor) is coming soon into communication market. For the purpose of developing a fit communication system which has little distortion of signal and attenuation, it is surely necessary to know about channel environments of powerline. Especially, the impedance measurement of the powerline and impedance matching are very important. As is known, since medium-voltage powerline (22.9 kV) is still working, it is not so simple to measure the powerline impedance. In our study, a portable impedance measurement equipment is developed. It consists of coupling capacitor, a drain coil and impedance matching transformer. The equipment is easily connected to medium voltage line and impedance of power line is measured using a network analyzer. Also, measurement results are used for impedance matching of PLC signal. In fact, matching transformer with several different impedances are used. The matching transformer is connected between coupling capacitor and signal port. In this paper, the developed portable impedance measurement equipment and impedance measurement results are presented. Also impedance matching technique using matching transformers will be explained. We showed the result of the improved performance by the impedance matching.
Low-Rate WPAN에서 경로탐색을 위한 위치기반 라우팅 메카니즘
이재조,허준,홍충선,이대영,Lee, Jae-Jo,Heo, Joon,Hong, Choong-Seon,Lee, Dae-Young 한국통신학회 2004 韓國通信學會論文誌 Vol.29 No.9B
최근 Low-Rate WPAN 기술에 관한 많은 연구가 진행되고 있다. Low-Rate WPAN 은 사용자가 실질적으로 인식하지 못하는 상황에서도 주변환경에 존재하는 많은 수의 센서를 통해 컴퓨터를 이용한 개선된 서비스제공에 목적을 두고있다. Low-Rate WPAN 환경을 구성하는 센서 디 B} 이스는 빈번한 이동성을 가지게 되고 새로운 경로 탐색을 위한 메카니즘을 필요로 하게 되므로, 본 논문에서는 센서 디바이스의 위치정보를 이용한 Low-Rate WPAN 환경에서의 효율척언 라우팅 메카니즘을 제안한다. 제안한 메카니즘은 기존 방법들에 비해 라우팅 메시지 수를 감소시킬 수 있음을 시뮬레이션을 통해 입증한다. Many researchers are now working in the Low-Rate WPAN environment. Low-Rate WPAN has as its goal the enhancing computer use by making many sensors available throughout the physical environment, but making them effectively invisible to the user. Low-Rate WPAN environment consists of wireless sensor devices that may move often. Movement of hosts results in a change in routes and the need of some mechanism for determining new routes. This paper suggests an approach to utilize location information to improve performance of a routing mechanism for Low-Rate WPAN Environment. Accordingly, we proved that the proposed mechanism results in a significant reduction in a number of routing messages when comparing with existing mechanisms.
이재조,박영진,오휘명,김관호,이대영 대한전기학회 2005 전기학회논문지 D Vol.54 No.6(D)
For broadband high-data-rate power line communication with the allocated frequency bandwidth from 2 to 30 MHz on medium voltage (MV) distribution power lines, a signal coupling unit is developed. The coupling unit is composed of a coupling capacitor for coupling communication signal, a drain coil, and an impedance matching part. The coupling capacitor made of ceramic capacitor is designed for transmission property of better than 1 dB in the frequency range. The drain coil is used for preventing low frequency high voltage from junction of medium voltage power line in case that a coupling capacitor is not working properly any more. Also, using ferrite core, a novel broadband impedance matching transformer is developed. A complete coupling unit with a coupling capacitor, a drain coil, and a matching transformer is housed by polymer for good isolation and distinguishing from high voltage electric facilities. Each is fabricated and its frequency behavior is tested. Finally, complete signal couplers are equipped in a MV PLC test bed and their performance are measured. The measurement shows that the coupling capacitor works excellently.