• 대한전자공학회논문지SD
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• 제37권9호
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• pp.38-46
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• 2000

본 논문에서는 신뢰성이 높고, 효율적으로 최적해에 도달하는 GA 학습기법을 광 연결에 응용하기 위한 소자 설계에 적용하였다. 실시간에 가까운 광 신호 처리를 위해 프로그래머블 SLM에 CGH 공간 필터를 입력하여 복합 광 신호 처리 시스템을 구성하여 실험하였다. 광학 실험에 의해 실제로 CCD 배열 검출기에서 얻어진 스폿 빔을 정략적인 데이터로 측정하기 위해 기하학적인 변형을 수행한 결과, $3{\times}3$ 스폿 빔에 대하여 그레이 레벨로서 스폿 빔들의 평균이 202, 최대값이 225, 최소값이 186으로 얻어졌고, 균일도가 $1.93{\times}10^{-1}$ 로서 시뮬레이션 결과와 유사하게 안정된 분포로 출력되었다.

• 한국자동차공학회논문집
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• 제22권6호
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• pp.23-30
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• 2014

This paper proposes a dead time compensation method for an AC motor drive using phase current polarity information which is detected based on a digital programmable low-pass filter (PLPF). The polarity detection using the PLPF is an alternative solution of a conventional method which uses a general low-pass filter (LPF) and hysteresis bands in order to avoid jittering due to noises. The PLPF not only adjusts its cutoff frequency according to the synchronous frequency of AC motors but also eliminates a gain attenuation and phase delay which are main problems of the general LPF. Through the PLPF, a fundamental component signal without gain and phase distortions is extracted from the measured raw current signal with noise. By use of the fundamental component, the polarity of current is effectively detected by reducing the hysteresis band. Finally, the proposed method compensates the dead time effects by adding or subtracting average voltage value to voltage references of the controller according to the detected current polarity information. The proposed compensation method is experimentally verified by compared with the conventional method.

• 대한의용생체공학회:의공학회지
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• 제28권3호
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• pp.423-428
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• 2007

Programmable FIR filters are used in various signal processing tasks in medical ultrasound imaging, which are one of the major factors increasing hardware complexity. A widely used method to reduce the hardware complexity of a programmable FIR filter is to encode the filter coefficients in the canonic signed digit (CSD) format to minimize the number of nonzero digits (NZD) so that the multipliers for each filter coefficients can be replaced with fixed shifters and programmable multiplexers (PM). In this paper, a new structure for programmable FIR filters with a improved frequency response and a reduced hardware complexity compared to the conventional shift-and-add architecture using PM is proposed for implementing a very small portable ultrasound scanner. The CSD codes are optimized such that there exists at least one common nonzero digit between neighboring coefficients. Such common digits are then implemented with the same shifters. For comparison, synthesisable VHDL models for programmable FIR filters are developed based on the proposed and the conventional architectures. When these filters have the same hardware complexity, pass-band ana stop-band ripples of the proposed filter are lower than those of the conventional filter by about $0.01{\sim}0.19dB$ and by about $5{\sim}10dB$, respectively. For the same filter performance, the hardware complexity of the proposed architecture is reduced by more than 20% compare to the conventional SaA architecture.