• 한국통신학회논문지
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• 제25권12A호
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• pp.1836-1842
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• 2000

이 논문은 레일레이 감쇄 채널 환경에서 IMT-2000 파일럿 심볼 구조의 W-CDMA 시스템 역방향 링크의 채널 추정에 관한 LMS 적용형 알고리즘 성능을 WMSA(Weighted Multi-Slot Averaging)(K=1,2,3), 일정 추정이득 (Constant estimation gain) 및 RLS 알고리즘 성능과 비교 분석하였다. 이 논문의 모형은 IMT-2000 3GPP 규격의 W-CDMA 채널 구조, 변조 및 파일럿 패턴을 이용하였다. 파일럿 심볼 위치의 채널추정은 LMS 알고리즘을 이용하고 데이터 심볼 위치의 채널보상은 선형 보간으로 수행하였다. 저속 도플러 주파수에서는 WMSA(K=1,2,3) 성능이 일정 추정이득, RLS 및 LMS 적응형 알고리즘 성능보다 우수하며, WMSA(K=1) 성능의 경우 일정 추정이득, RLS 및 LMS 적응형 알고리듬 성능과는 큰 차이가 없다. 그리고 LMS 알고리즘 성능은 WMSA(K=1) 성능과 매우 비슷한 결과를 얻었다. 그러나 도플러 주파수가 고속화될수록 LMS 알고리즘의 성능이 WMSA(K=1), 일정 추정이득 및 RLS 알고리즘 성능보다 우수함을 확인하였다.

• 전기학회논문지
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• 제56권11호
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• pp.2033-2035
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• 2007

This paper proposes a novel iterative LMS-based decision feedback equalizer for short burst transmission with relatively short training sequence. In the proposed equalizer, the longer concatenated training sequence can provide the more sufficient channel information and the reused original training sequence can provide the correct decision feedback information. In addition, the overall adaptive processing is performed using the low complexity LMS algorithm. The study shows the performance of the proposed method is enhanced with the number of iterations and, furthermore, better than that of the conventional LMS-based DFEs with the training sequence of longer or equal length. Computational complexity is increased linearly with the number of iterations.

• 조명전기설비학회논문지
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• 제15권5호
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• pp.34-40
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• 2001

본 논문에서는 화력발전소 보일러 운전원 근무실 소음제어를 위하여 협대역 능동소음 제어시스템을 제안하였다. 제안된 시스템은 기준입력으로 구형파를 사용하여 기본파는 물론 고조파까지 한꺼번에 제어할 수 있게 하였으며, adjoint LMS 알고리즘을 사용하여 기존의 filtered-X LMS 알고리즘을 사용한 경우보다 계산량을 줄였다. 컴퓨터 시뮬레이션 결과, 기존의 광대역 능동소음 제어시스템에 비해 훨씬 작은 자수의 적응 필터를 사용하였으나, 더 우수한 특성을 보였다.

• 전기학회논문지P
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• 제65권3호
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• pp.171-177
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• 2016

Noise problem that occurs in living environment is a big trouble in the economic, social and environmental aspects. In this paper, the filtered-X LMS algorithms, the adjoint LMS algorithms, and the robust adjoint LMS algorithms will be introduced for applications in active noise control(ANC). The filtered-X LMS algorithms is currently the most popular method for adapting a filter when the filter exits a transfer function in the error path. The adjoint LMS algorithms, that prefilter the error signals instead of divided reference signals in frequency band, is also used for adaptive filter algorithms to reduce the computational burden of multi-channel ANC systems such as the 3D space. To improve performance of the adjoint LMS ANC system, an off-line measured transfer function is connected parallel to the LMS filter. This parallel-fixed filter acts as a noise controller only when the LMS filter is abnormal condition. The superior performance of the proposed system was compared through simulation with the adjoint LMS ANC system when the adaptive filter is in normal and abnormal condition.

• 조명전기설비학회논문지
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• 제17권6호
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• pp.147-153
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• 2003

본 논문에서는 외부에 위치하는 소음원에 의하여, 창문 등과 같이 부분적인 개구부를 가지는 실내 공간에 소음이 전파될 때, 적응필터를 이용하여 이를 제어하는 능동 방음벽을 구현하였다. 적응필터의 수렴성을 증가시키기 위하여 다중채널 leaky LMS 알고리즘을 사용하였으며 창문 등의 개구부를 통하여 들어오는 소음을 제거하기 위하여 새로운 형태의 능동방음벽을 제안하였다. 기존의 ANC 기법을 이용한 기법과 제안한 기법을 TMS320C33 DSP를 이용한 실험을 통해 비교 분석하였다. 오차 마이크로폰의 위치에서는 ANB가 다소 좋은 결과를 얻었으나 두 경우 모두 비교적 좋은 결과를 얻을 수 있었지만, 전체 위치에서 소음의 감쇄를 소음계를 이용해 측정한 결과 ANB가 훨씬 좋은 결과를 보였다. ANC의 경우 보일러 소음의 경우는 평균적으로 차이가 거의 없었으며 위치에 따라서는 증가하는 곳도 있었으나, ANB의 경우는 단일 소음 및 보일러 소음 모두 증가하는 곳은 한 곳도 없었으며 평균적으로도 ANC의 경우보다 훨씬 좋은 결과를 보였다.

• 대한전자공학회논문지
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• 제26권9호
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• pp.1444-1452
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• 1989

This paper describes the implementation of a real time fetal ECG monitoring system in which an adaptive multi-channel noise canceller is realized using the Texas Instruments TMS32020 progrmmmable ditital signal processor. An ECG signal from the electrode placed on the mother's abdomen and three ECGs from those on the chest are applied as the desired signal and the referened inputs, respectively, of the multi-channel filter. The coefficients of the filter are updated using the LMS algorithm such that the output of the multi-channel filter copies the maternal ECG embedded in the abdominal ECG. The enhanced fetal ECG is obtained by subtracting the filter output from the abdominal ECG, and the difference signal is recorded. Both off-line and on-line experimental results are presented to verify the effectiveness of the parameters for the digital signal processing algorithms and the prototype system.

• 대한기계학회논문집A
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• 제25권9호
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• pp.1410-1415
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• 2001

Active control of sound radiation from a vibrating rectangular plate by a steady-state harmonic point force disturbance is experimentally studied. Structural excitation is achieved by two piezoceramic actuators mounted on the panel. Two accelerometers are implemented as error sensors. Estimated radiated sound signals using vibro-acoustic path transfer function are used as error signals. The vibro-acoustic path transfer function represents system between accelerometers and microphones. The approach is based on a multi-channel filtered-x LMS algorithm. The results shows that attenuation of sound levels of 11dB, 10dB is achieved.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집A
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• pp.608-612
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• 2000

Active control of sound radiation(using active structural acoustic control) from a vibrating rectangular plate by a steady-state harmonic point force disturbance is experimentally studied. Control structural input are achieved by two piezoceramic actuators bonded to the surface of the panel. Two accelerometers are implemented as error sensors. Estimated radiated sound signals using vibro-acoustic path transfer function are used as error signals. The vibro-acoustic path transfer function represents system between accelerometers and microphones. The control approach are based on a multi-channel filtered-x LMS algorithm. The results demonstrate that attenuation of sound levels of 3dB, 13dB are achieved.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 추계종합학술대회 논문집
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• pp.5-8
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• 1999

In this paper, we present narrowband interference (NBI) cancelling algorithm applied to wideband spread spectrum system. We introduce multi-carrier transmission technique to overcome hardware inplementation difficulty of wideband spreading above 40MHz and to enhance NBI performance. A direct-sequence spread spectrum receiver using both decision-feedback and two sided LMS filters for combating narrowband interference is applied. We show that performance of this receiver outperforms conventional NBI rejection systems in tone jamming, partial band jamming, and impulsive channel through the bit error ratio evaluation. In addition, we propose a new technique to improve the performance of time domain NBI rejection algorithm sensitive to impulsive channel.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(1)
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• pp.89-92
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• 2001

In this paper, adaptive multi-stage parallel interference cancellation (PIC) receiver is considered for a multi-rate DS-CDMA system. In each stage of the adaptive multi-stage PIC receiver, multiple access interference (MAI) estimates are obtained using the sub-bit estimates from the Previous stage and the adaptive weights for the sub-bit estimates. The adaptive weights are obtained by minimizing the mean squared error between the received signal and its estimate through a least mean square (LMS) algorithm. It is shown that the adaptive multi- stage PIC receiver achieves smaller BER than the matched filter receiver, multi-stage PIC receiver, and multi-stage partial PIC receiver for the multi-rate DS-CDMA system in a Rayleigh fading channel.