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김기택(Kim Gi-Taek),김만배(Kim Man-Bae),김봉택(Kim Bong-Taek) 한국철도학회 1998 한국철도학회 학술발표대회논문집 Vol.- No.-
Train wheels tend to wear abrasion due to frequent startings and brakings. They are important factors of train safety and noise. However, it is difficult and inaccurate to measure their shape and profile manually. Profile measurement system of train wheel with image processing is proposed. The system consists of CCD cameras, PCI image grabber board, and PC operated on Windows"95. Image processing algorithms such as filtering, histogram equalization, and edge detection are presented, and some processing results are illustrated.
디지털 PLL을 이용한 ATS 지상자 코일 Q 측정장치 개발
김기택(Kim Gi-Taek),임기택(Lim Kee-Taek),최정용(Choi Jung-Yong),김봉택(Kim Bong-Taek) 한국철도학회 2000 한국철도학회 학술발표대회논문집 Vol.- No.-
For safety reason ATS(Automatic Train Stop) system is being used, which is a kind of communication system with a feedback amplifier and a transformer on the train and wayside coils. The coils are highly resonant LC circuits, also have very high Q(Quality) factors. The Q factors of wayside ATS coils are to be maintained high enough for the amplifier to operate reliably. In this paper a novel Q measurement system is proposed. The system measures the resonant frequency and the bandwidth of the ATS coils, by controlling the phase difference between the transformer and the coil using digital PLL(Phase Locked Loop). The overall configuration and algorithms of the proposed system and the digital PLL control schemes are presented in details. The experimental waveforms are shown to verify the system performances.
이미지 처리기술을 이용한 펜터그라프 섭판 측정장치 개발
김기택(Kim Gi-Taek),임기택(Lim Kee-Taek),김봉택(Kim Bong-Taek) 한국철도학회 1998 한국철도학회 학술발표대회논문집 Vol.- No.-
Pentagraphs are used to supply electric power to train via trolley lines. The higher train speed is, the higher voltage and current levels are. Since electric power is supplied with slinding contact, localized abrasion is inevitable. It is difficult and dangerous to measure their shape manually. Measurement system of pentagraph slider with ultrasonic processing has been reported. In this paper, measurement system with image processing is proposed. The system consists of CCD cameras, image grabber board, and PC operated on Windows"95. Image processing algorithms are presented and some results are illustrated.
웨이블릿 변환과 GPS 정밀시각동기를 이용한 전력계통 고장점 모니터링 시스템에 관한 연구
김기택(Kim Gi Taek),김혁수(Kim Hyuck Soo),최정용(Choi Jung Yong) 강원대학교 산업기술연구소 2001 産業技術硏究 Vol.21 No.1
A continuous and reliable electrical energy supply is the objective of any power system operation. A transmission line is the part of the power system where faults are most likely to happen. This paler describes the use of wavelet transform for analyzing power system fault transients in order to determine the fault location. Synchronized sampling was made possible by precise time receivers based on GPS time reference, and the sampled data were analyzed using wavelet transform. This paper describes a fault location monitoring system and fault locating algorithm with GPS, DSP processor, and data acquisition board, and presents some experimental results and error analysis.
대기압 유전체배리어방전으로 합성 및 산화 처리된 SiOxCy(-H) 박막의 부식방지 특성
김기택(Gi-Taek Kim),김윤기(Yoon Kee Kim) 한국표면공학회 2020 한국표면공학회지 Vol.53 No.5
A SiOxCy(-H) thin film was synthesized by atmospheric pressure dielectric barrier discharge(APDBD), and a SiO₂-like layer was formed on the surface of the film by oxidation treatment using oxygen plasma. Hexamethylcyclotrisiloxane was used as a precursor for the SiOxCy(-H) synthesis, and He gas was used for stabilizing APDBD. Oxygen permeability was evaluated by forming an oxidized SiOxCy(-H) thin film on a PET film. When the single-layer oxidized SiOxCy(-H) film was coated on the PET, the oxygen gas permeability decreased by 46% compared with bare PET. In case of three-layer oxidized SiOxCy(-H) film, the oxygen gas permeability decreased by 73%. The oxygen permeability was affected by the thickness of the SiO₂-like layer formed by oxidation treatment rather than the thickness of the SiOxCy(-H) film. The excellent corrosion resistance was demonstrated by coating an oxidized SiOxCy(-H) thin film on the silver-coated aluminum PCB for light emitting diode (LED).
이해춘,박태열,김기택,Lee, Hae-Chun,Park, Tae-Yeol,Kim, Gi-Taek 강원대학교 산업기술연구소 1999 産業技術硏究 Vol.19 No.-
A single phase to three phase power converter with cost effective and simple structure is proposed. The converter consists of rectifier and inverter. The rectifier is composed of a half wave rectifier, a dc link capacitor, and a current limiting inductor, and the inverter is of only two switches with PWM control. For negative sequence operation the inverter output voltage leads the line input by $60^{\circ}$, and for positive sequence operation the inverter output voltage leads by $60^{\circ}$. We can see that positive sequence operation shows higher output voltage, slight harmonic distortion(2%), and better performances such as high efficiency and high power factor. A mathematical model for system analysis is provided, and specifications for selection and control scheme both for start-up and for steady state are analyzed. comparison and operational limits of positive and negative sequence operation are performed, and simulations and experiments are executed to verify the proposed.
충전기 고조파 잡음에 강인한 배터리 내부저항 측정 시스템
이형규(Hyung-Kyu Lee),김기택(Gi-Taek Kim) 한국전기전자학회 2020 전기전자학회논문지 Vol.24 No.4
배터리를 사용함에 따라 노화가 진행되면 배터리의 충전 가능 용량을 나타내는 State of Health(SoH)가 줄어들게 된다. 배터리 모니터링 시스템(BMS)에서 SoH를 추정하는 것이 매우 중요하며, 이를 위해 배터리 내부 저항을 측정하는 방법이 많이 사용된다. 일반적으로 배터리에 특정한 주파수의 전류원을 인가하고 전압응답을 측정하여 내부저항을 연산한다. 충전기가 동작할 경우 전압응답에 충전 고조파 잡음이 발생하여 저항 측정의 정확도가 떨어진다. 본 논문에서는 충전잡음의 영향을 제거하기 위하여 강인한 배터리 내부저항 측정 알고리즘을 제안하였다. 전류원 신호와 전압응답 신호를 일정한 주기 동안 적분하여 잡음을 제거하는 방법으로 우수한 정확도와 안정된 연산결과를 보였다. 무정전 전원장치용 BMS에 적용하여 제안한 방법의 유용함을 입증하였다. The effects of battery aging limit the rechargeable capacity, State of Health(SoH). It is very important to estimate the SoH in the battery monitoring system(BMS) and many algorithms of measuring the internal resistance of the battery were proposed. A method is used by applying a current source of a specific frequency to the battery and measuring the voltage response. When charging harmonic noise is generated in the voltage response, it results in poor resistance measurement accuracy. In this paper, a robust battery internal resistance measurement algorithm is proposed to eliminate the effect of charging noise by integrating the current source and voltage response signals for a certain period. It showed excellent accuracy and stable measurement results. Applying to the BMS for uninterruptible power supply, the usefulness of the proposed method is verified.