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성긴임펄스 응답 시스템을 위한 부밴드 IPNLMS 적응필터
손상욱(Sang-Wook Sohn),최훈(Hun Choi),배현덕(Hyeon-Deok Bae) 대한전기학회 2011 전기학회논문지 Vol.60 No.2
In adaptive filtering, the sparseness of impulse response and input signal characteristics are very important factors of it's performance. This paper presents a subband improved proportionate normalized least square (SIPNLMS) algorithm which combines IPNLMS for impulse response sparseness and subband filtering for prewhitening the input signal. As drawing and combining the advantage of conventional approaches, the proposed algorithm, for impulse responses exhibiting high sparseness, achieve improved convergence speed and tracking ability. Simulation results, using colored signal(AR(4)) and speech input signals, show improved performance compared to fullband structure of existing methods.
손상욱(Sang-Wook Sohn),임영빈(Young-Bin Lim),윤재준(Jae-Jun Youn),박영태(Young-Tae Park),배현덕(Hyeon-Deok Bae) 대한전기학회 2010 대한전기학회 학술대회 논문집 Vol.2010 No.7
전력신호의 전력품질 모니터링에서 고조파와 중간고조파의 정확한 예측과 검출은 중요한 요소이다. 중간고조파는 크기가 고조파에 비해 작아 검출에 어려움이 따르므로 해당 대역의 고조파를 제거한 후 중간 고조파를 검출하는 것이 보다 용이한 방법이다. 본 연구에서는 필터뱅크와 적응필터를 이용하여 고조파를 예측, 제거한 후 중간고조파를 검출하는 기법을 제안한다. 제안기법은 적응필터를 사용하므로 전력신호의 시변환경에서도 중간고조파 검출의 정확성을 높일 수 있다. 제안기법의 성능은 중간고조파별 적응필터의 길이와 지연정도에 따른 예측정확도를 시뮬레이션을 통해 검증한다.
FIR MIMO 시스템을 위한 부밴드 적응 블라인드 등화 알고리즘
손상욱(Sang-Wook Sohn),임영빈(Young-Bin Lim),최훈(Hun Choi),배현덕(Hyeon-Deok Bae) 대한전기학회 2010 전기학회논문지 Vol.59 No.2
If the data are pre-whitened, then gradient adaptive algorithms which are simpler than higher order statistics algorithms can be used in adaptive blind signal estimation. In this paper, we propose a blind subband affine projection algorithm for multiple-input multiple-output adaptive equalization in the blind environments. All of the adaptive filters in subband affine projection equalization are decomposed to polyphase components, and the coefficients of the decomposed adaptive sub-filters are updated by defining the multiple cost functions. An infinite impulse response filter bank is designed for the data pre-whitening. Pre-whitening procedure through subband filtering can speed up the convergence rate of the algorithm without additional computation. Simulation results are presented showing the proposed algorithm's convergence rate, blind equalization and blind signal separation performances.
적응 부밴드 필터링을 이용한 전력계통 시변 주파수와 고조파 검출 및 추적
손상욱(Sang-Wook Sohn),최훈(Hun Choi),배현덕(Hyeon-Deok Bae) 대한전기학회 2009 전기학회논문지 Vol.58 No.4
In this paper, a subband filtering and adaptive prediction technique for analyzing harmonics in power systems is presented. In this method, the filter banks are designed to decompose odd and even order harmonics separately. The adaptive prediction has been employed reduce the transient and white noise effect in time varying harmonics detecting and tracking. The frequencies and amplitudes of the decomposed harmonics are estimated by recursive algorithm. To demonstrate the performances of the developed technique, computer simulations to the signal with the time-varying frequency and THD are carried out.
LMS기반 트랜스버설 필터의 컨벡스조합을 위한 부밴드 적응알고리즘
손상욱(Sang-Wook Sohn),이경표(Kyeong-Pyo Lee),최훈(Hun Choi),배현덕(Hyeon-Deok Bae) 대한전기학회 2013 전기학회논문지 Vol.62 No.1
Convex combination of two adaptive filters is an efficient method to improve adaptive filter performances. In this paper, a subband convex combination method of two adaptive filters for fast convergence rate in the transient state and low steady state error is presented. The cost function of mixing parameter for a subband convex combination is defined, and from this, the coefficient update equation is derived. Steady state analysis is used to prove the stability of the subband convex combination. Some simulation examples in system identification scenario show the validity of the subband convex combination schemes.
손상욱(Sang-wook Sohn),류근택(Geun-taek Ryu),배현택(Hyeon-Deok Bae) 대한전자공학회 2008 電子工學會論文誌 IE (Industry electronics) Vol.45 No.2
본 논문에서는 TFT-LCD 편광필름의 결함을 검출하기위한 새로운 영상처리기법을 제안한다. 레이저 반사광을 이용하여 회득한 편광필름 영상에서 우선 배경잡음을 제거하기 위하여 형태론적 영상처리기법(열림, 닫힘)을 사용한다. 배경잡음이 제거된 영상으로부터 결함을 검출하기 위하여 2차원 LMS 적응 예측기를 사용하여 밝은 결함을 검출하고 통계적 특성을 이용하여 어두운 결함을 검출한다. 산업현장에서 제공된 TFT-LCD 편광필름을 사용하여 제안된 기법의 성능을 평가한다. In this paper, we propose a new image processing technique that reliably detects the various defects of TFT-LCD polarizing films. The image of polarizing film is acquisited from reflected laser beam. First, we apply the morphological image processing technique to remove the background noise. Next, we use the 2-dimensional LMS adaptive filtering and statistical characteristics to detect the white and black defects. Performance of the proposed method is evaluated on real TFT-LCD polarizing film samples.
디지털 보청기의 성긴 궤환경로 보상을 위한 부밴드 적응필터
손상욱(Sang-Wook Sohn),임영빈(Young-Bin Lim),윤재준(Jae-Jun Youn),유동구(Dong-Gu Yoo),배현덕(Hyeon-Deok Bae) 대한전기학회 2010 대한전기학회 학술대회 논문집 Vol.2010 No.7
디지털 보청기의 음향궤환 경로인 벤트는 임펄스 응답이 성긴특성을 가진다. 성긴 임펄스 응답 시스템에 적합한 적응 알고리즘으로는 IPNLMS가 유용한 것으로 알려져있다. 본 논문에서는 디지털 보청기의 벤트에 의한 음향궤환을 제거하기위해 부밴드 IPNLMS을 제안한다. 그리고 보청기에서 중요한 난청 보상필터도 대역별로 설계하여 부밴드 궤환제거에 활용한다. 제안기법의 성능을 전밴드 IPNLMS와 SNLM와 비교하여 성능을 입증한다.
베타선 흡수법을 이용하는 미세먼지 측정시스템을 위한 잡음제거 방법
최훈(Hun Choi),손상욱(Sang-Wook Sohn),배현덕(Hyeon-Deok Bae) 대한전기학회 2012 전기학회논문지 Vol.61 No.11
The Beta-ray absorption method (BAM) gives a good solution for measuring the mass concentration of atmospheric particles(PM10 and PM2.5). To determine particular matters (PM) concentration, a ratio of the number of detected beta-ray intensity passing through the clean filter and the dust-sampled filter is used. These intensity data measured in air pollution monitoring such as PM10 and PM2.5 usually contained the additive noise(thermal noise, power supply noise and etc.). Therefore, the estimation performance of mass concentration can be deteriorated by these noises. In this paper, we present a new noise reduction method that is essentially required to develope an automatic continuous PM monitoring system using beta-ray absorption method. By combining the block data averaging technique and curve fitting, in the proposed method, the additive noise can be reduced in the measured data. To evaluate the performance of the proposed method, computer simulations were performed with computer generated signals as the input.
최훈(Hun Choi),손상욱(Sang-Wook Sohn),배현덕(Hyeon-Deok Bae) 대한전기학회 2014 전기학회논문지 Vol.63 No.3
This paper presents a new approach to improve the signal to noise ratio (SNR) for local seismic disaster preventing system in densely populated area. The seismic data measured in the local site includes various sensing noises (offset or measurement noise) and man-made/natural noises (road and rail traffic noise, rotating or hammering machinery noise, human activity noise such as walking and running, wind/atmospheric pressure-generated noise, etc.). These additive noises are different in time and frequency characters. The proposed method uses 3-stages processing to reduce these different additive noises. In the first stage, misalignment offset noise are diminished by time average processing, and then the second and third stages, coherent/incoherent noises such as man-made/natural noises are suppressed by array stacking. In addition, we derived the theoretical equation of the SNR gain improved by the proposed method. To evaluate the performance of the proposed method, computer simulations were performed with real seismic data and test equipment generated data as the input.