• ETRI Journal
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• 제32권6호
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• pp.921-931
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• 2010

It has been shown that the principal subspace-based multichannel Wiener filter (MWF) provides better performance than the conventional MWF for suppressing interference in the case of a single target source. It can efficiently estimate the target speech component in the principal subspace which estimates the acoustic transfer function up to a scaling factor. However, as the input signal-to-interference ratio (SIR) becomes lower, larger errors are incurred in the estimation of the acoustic transfer function by the principal subspace method, degrading the performance in interference suppression. In order to alleviate this problem, a principal subspace modification method was proposed in previous work. The principal subspace modification reduces the estimation error of the acoustic transfer function vector at low SIRs. In this work, a frequency-band dependent interpolation technique is further employed for the principal subspace modification. The speech recognition test is also conducted using the Sphinx-4 system and demonstrates the practical usefulness of the proposed method as a front processing for the speech recognizer in a distant-talking and interferer-present environment.

• 한국음향학회지
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• 제39권5호
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• pp.490-496
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• 2020

본 논문에서는 잡음 환경에서 다채널 위너 필터의 성능을 향상시키기 위한 방법을 제안한다. 부공간(subspace) 기반의 다채널 위너 필터를 설계하는 경우, 목적 신호가 단일 음원인 경우는 음성 상관 행렬의 주성분 부공간에서 음성 성분을 추정할 수 있다. 이 때, 음성 상관 행렬은 음성과 간섭 잡음의 교차 상관도가 음성 상관 행렬에 비해 무시할만한 수준이라는 가정하에 신호 상관 행렬에서 간섭 잡음의 상관 행렬을 차감하여 추정하게 된다. 그러나 간섭 잡음 수준이 높아지게 되면 이러한 가정이 더 이상 유효하지 않게 되며 이에 따라 주성분 부공간 추정 오차도 증가하게 된다. 본 연구에서는 음성 존재 확률과 목적 신호의 방향 벡터를 이용하여 주성분 부공간을 보정하는 방법을 제안한다. 주성분 부공간에서 다채널 음성 존재 확률을 유도하고 주성분 부공간 벡터를 보정하는데 적용하였다. 실험을 통해 제안하는 방법이 잡음 환경에서 다채널 위너 필터의 성능을 향상시키는 것을 확인할 수 있다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 하계종합학술대회 논문집(1)
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• pp.205-208
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• 2000

In this paper, we design Tracking Filter that is principal component of Frequency Hopping System. This filter can acquire hopping pattern in short time and track it at high speed. This is high Q, narrowband, RF filter whose center frequency is controlled digitally between 30MHz ∼ 88MHz.

• 대한수학회논문집
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• 제14권2호
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• pp.287-293
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• 1999

In this paper, we give an affirmative answer to the question raised in [5]; whether L((P)) is principal or not. Using this fact, we try to give concrete form of module of quotient with respect to a torsion theory determined by L((P)).

• 대한음성학회지:말소리
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• 제53호
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• pp.93-102
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• 2005

The performance of a speech recognition system is generally degraded in telephone environment because of distortions caused by background noise and various channel characteristics. In this paper, data-driven temporal filters are investigated to improve the performance of a specific recognition task such as telephone speech. Three different temporal filtering methods are presented with recognition results for Korean connected-digit telephone speech. Filter coefficients are derived from the cepstral domain feature vectors using the principal component analysis. According to experimental results, the proposed temporal filtering method has shown slightly better performance than the previous ones.

• 조명전기설비학회논문지
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• 제29권12호
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• pp.1-7
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• 2015

In this paper, we propose a second-order fiber flexible comb filter based on a polarization-diversity loop(PDL). The proposed filter consists of a polarization beam splitter, four half-wave plates(HWPs), and three high birefringence fiber(HBF) segments. In the previous Solc-type second-order filter based on the PDL, HBF segments were fusion-spliced with a fixed angle offset between their principal axes with each other. But, the proposed filter implemented by inserting two HWPs between three HBF segments has a great flexibility in adjusting relative angular difference between the principal axes of two adjacent HBF segments. Owing to this flexibility, second-order transmission spectra, which had a channel spacing of ~0.8nm, could be interleaved by controlling the orientation angles of four HWPs. The output transmission spectra of the proposed filter were theoretically analyzed and experimentally verified.

• Journal of the Optical Society of Korea
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• 제12권3호
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• pp.147-151
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• 2008

This paper proposes a new polarization-independent Sagnac birefringence loop structure-based multiwavelength-periodic filter and presents measurements and analysis of its spectrum. The filter can be used in several schemes by adjusting the orientation angles of two quarter waveplates and the operating characteristics in the reflection type are analyzed including dispersion and polarization mode dispersion at each principal axis. This filter has polarization-independent spectra but a polarization-dependent dispersion, consequently polarization mode dispersion whose values changes with operating schemes.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 학술대회지
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• pp.764-767
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• 2004

The performance of a speech recognition system is generally degraded in telephone environment because of distortions caused by background noise and various channel characteristics. In this paper, data-driven temporal filters are investigated to improve the performance of a specific recognition task such as telephone speech. Three different temporal filtering methods are presented with recognition results for Korean connected-digit telephone speech. Filter coefficients are derived from the cepstral domain feature vectors using the principal component analysis.

• 한국멀티미디어학회논문지
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• 제10권1호
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• pp.26-35
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• 2007

본 논문은 연속적으로 입력되는 비디오 영상에서 효과적인 얼굴 검출기와 칼만 필터를 이용하여 강인하게 얼굴을 추적하는 시스템을 제안한다. 효과적인 얼굴 검출기를 구성하기 위해 간단한 다섯 가지 타입의 Haar-like 특징값들을 이용하여 얼굴 특징을 추출한다. 추출된 특징값들은 PCA(Principal Component Analysis)를 이용하여 재해석되고, 해석된 주성분들을 SVM(Support Vector Machine)의 입력 값으로 사용하여 얼굴과 배경으로 분류한다. 검출된 얼굴의 정적정보와 프레임간 변화량을 이용한 동적정보를 칼만 필터(Kalman Filter)에 적용하여 얼굴을 추적한다. 실시간에 적용 가능한 시스템을 구현하기 위하여 얼굴 검출회수를 조정하여 처리속도를 향상시켰다. 실험결과, 평균 93.3%의 추적 성공률과 초당 15 프레임 처리 성능으로 강인한 실시간 얼굴 추적이 가능함을 보여주었다.

• 한국IT서비스학회지
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• 제6권3호
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• pp.241-249
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• 2007

This paper describes a real-time face tracking system using effective detector and Kalman filter. In the proposed system, an image is separated into a background and an object using a real-time updated face color for effective face detection. The face features are extracted using the five types of simple Haar-like features. The extracted features are reinterpreted using Principal Component Analysis (PCA), and interpreted principal components are used for Support Vector Machine (SVM) that classifies the faces and non-faces. The moving face is traced with Kalman filter, which uses the static information of the detected faces and the dynamic information of changes between previous and current frames. The proposed system sets up an initial skin color and updates a region of a skin color through a moving skin color in a real time. It is possible to remove a background which has a similar color with a skin through updating a skin color in a real time. Also, as reducing a potential-face region using a skin color, the performance is increased up to 50% when comparing to the case of extracting features from a whole region.