• Convergence Security Journal
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• v.13 no.3
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• pp.9-15
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• 2013

Calculating of matching cost is an important for efficient stereo matching. To investigate the performance of matching process, the concepts of the existing methods are introduced. Also we analyze the performance and merits of them. The simplest matching costs assume constant intensities at matching image locations. We consider matching cost functions which can be distinguished between pixel-based and window-based approaches. The Pixel-based approach includes absolute differences (AD) and sampling-intensitive absolute differences (BT). The window-based approach includes the sum of the absolute differences, the sum of squared differences, the normalized cross-correlation, zero-mean normalized cross-correlation, census transform, and the absolute differences census transform (AD-Census). We evaluate matching cost functions in terms of accuracy and time complexity. In terms of the accuracy, AD-Census method shows the lowest matching error ratio (the best solution). The ZNCC method shows the lowest matching error ratio in non-occlusion and all evaluation part. But it performs high matching error ratio at the discontinuities evaluation part due to blurring effect in the boundary. The pixel-based AD method shows a low complexity in terms of time complexity.

• Proceedings of the Acoustical Society of Korea Conference
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• 1998.06d
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• pp.64-67
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• 1998

원격지간 화상회의 시스템에서 화자의 위치에 따른 카메라 제어를 위해서는 마이크로폰 배렬(Microphone Array)로 수음한 음성신호에 대해 각 마이크로폰간의 빠른 지연시간 추정이 요구된다. 본 연구에서는 음원위치 추정을 위한 지연시간(Time delay) 계산을 위해 AMDF(Average Magnitude Difference Function)를 적용하여 연산시간을 단축시키는데 목적을 두고 있다. 기본의 상호상관함수 (Cross-correlation )알고리즘 과 본 연구에서 적용한 AMDF 알고리즘을 비교하기 위해 SNR 10dB 와 20dB 인 200Hz, 500Hz, 1kHz, 2kHz의 정현파 합성신호와 단음절 음성신호에 대해 시뮬레이션을 행하였다. 시뮬레이션 결과 AMDF 알고리즘의 정확한 지연시간 추정을 확인하였다.

• The Journal of the Acoustical Society of Korea
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• v.11 no.1E
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• pp.64-72
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• 1992

본 연구는 음장의 주관 확산감과 관련있는 두 귀에 입사하는 신호의 상호상관도와 청각유발 반 응과의 관계를 밝히기 위한 것이다. 실험은 중신 주파수가 500Hz인 1/3옥타브 대역잡음을 이용하여 IACC를 0.95에서 0.1까지 가변시키면서 AER을 기록하였다. IACC와 주관확산감과의 함수 결과와 비교 하기 위하여 기준음과 테스트음의 쌍을 교대로 제시하면서 AER을 청각 부위에서 기록하였다. 그 결과 테스트음에 대해 IACC와 관련된 정보는 AER의 반응시간에 나타났고, IACC의 크기가 감소함에 따라 반응시간이 길어지는 경향이 나타났다. 여기에서 IACC와 AER의 반응시간과는 선형관계를 나타냈다. 이 결과는 청각계에서 음장의 IACCDP 반응하는 뉴런이나 메카니즘이 존재하는 것을 암시하고 있음을 알 수 있다.

• Journal of the Institute of Convergence Signal Processing
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• v.9 no.4
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• pp.304-312
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• 2008

Orthogonal codes like Walsh and Golay codes may have large correlation value when they are not synchronized, hence they are seldom used in asynchronous CDMA systems. Wysocki[1] showed that by multiplying the original Walsh-Hadamard matrix with an orthogonal transformation matrix the resultant matrix sustains orthogonality between row vectors and their cross-correlation can be reduced. Soberly and Wysocki[2] proposed similar scheme on Golay codes. This implies that using the proper orthogonal transformation cross-correlation of Walsh and Golay codes can be reduced, and the transformed codes can be used for user separation in the CDAM reverse link. In this paper we discuss cross-correlation related parameters which affect the performance of an asynchronous CDMA link, and we investigate the correlation properties of the transformed codes. When we designed orthogonal transformation matrices for Walsh and Golay codes, we minimized the maximum value of aperiodic cross-correlation of the codes ($ACC_{max}$) or the mean square value of the aperiodic cross-correlation($R_{cc}$) with preserving the orthogonality of the modified codes. We also evaluate the asynchronous CDMA system that uses the transformed Walsh and Golay codes.

• 한국지구물리탐사학회:학술대회논문집
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• 2006.06a
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• pp.41-50
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• 2006

The crustal structure of Korean Peninsula have been investigated by analyzing group velocity dispersion data of surface wave. Cross.correlation of seismic background motions (Campillo and Paul, 2003; Shapiro et al., 2005) has been applied to estimate the short.period Rayleigh. and Love.wave group velocity dispersion characteristics of the region. Standard processing procedures were applied to the cross.correlation, except that signal whitening was used in place of one.bit sampling equalize power in signals from different times. Multiple.filter analysis was used to extract the group velocities from the estimate Green's functions, which were then use to image the spatially varying dispersion at periods between 0.5 and 20 seconds. The tomographic inversion technique used inverted all periods simultaneously to provide a smooth dispersion curve as a function of period in addition to the usual smooth spatial image for a given period. The Gyeongsang Basin in the southeastern part of the peninsula is clearly resolved with lower group velocities.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.11 no.2
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• pp.110-118
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• 1997

This paper describes the dissipation factor measuring techniques of insulating oil on operating pole transformers by using digital signal processor. After applying voltage to the condenser which is in¬stalled in a transformer, acquiring source voltage and current of condenser and using cross-correla¬tion techniques, we can check the dissipation factor of insulating oil. To improve measuring accuracy and the speed of process, we use hardware such as TMS320C31 DSP board and software such as cross -correlation techniques. We simulated the measuring accuracy and the degree of the noise effect of this new measuring techniques by using computer simulation, and compared the simplified measuring devices with Schering bridge on degraded insulating oil. The result showed that this measuring tech¬nique can be used as diagnostic method on the pole transformers.

• The Journal of the Acoustical Society of Korea
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• v.20 no.4
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• pp.22-28
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• 2001

This paper describes the implementation of a robust speaker position location system using the voice signal received by microphone array. To be robust to the reverberation which is the major factor of the performance degradation, low-frequency phase restoration algorithm which eliminates the influence of reverberations using the low-frequency information of the CPSP function is proposed. The implemented real-time system consists of a general purpose DSP (TMS320C31 of Texas instruments), analog part which contains amplifiers and filters, and digital part which is composed of the external memory and 12-bit A/D converter. In the real conference room environment, the implemented system that was constructed by the proposed algorithms showed better performance than the conventional system. The error of the TDOA estimation reduced more than 15 samples.

• Journal of the Institute of Convergence Signal Processing
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• v.8 no.1
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• pp.44-50
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• 2007

In this paper generating algorithms of the conventional chaos code sequences and a new chaos code sequence derived from the real and imaginary parts of FFT of one chaos code sequence, and the time-frequency function characteristics of generated code sequences to measure the signal resolution, are considered. And two chaos based QCSK digital communication systems-one with two different chaos code sequences, the other with FFT of one chaos code sequence-are analyzed in AWGN and fading communication channels. After analyzing the correlation functions of such sequences, the delta-like autocorrelation and near zero crosscorrelation functions of them are very suitable for chaos based spread spectrum communication systems, is verified. Through evaluating the performance of two chaos based QCSK systems above using Monte-Carlo simulation, the improvement of performance in the latter QCSK system compare favorably with that of the former system, is shown.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.113-116
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• 1999

신호 대 잡음비가 낮은 환경에서 센서 어레이에 입사된 입력 신호 사이의 지연시간 추정(Time Delay Estimation, 이하 TDE)은 높은 분해능이 요구된다. 본 연구에서는 높은 분해능의 TDE를 구하기 위해 상호상관함수(Cross-Correlation)에 평균 차 함수(Average Magnitude Difference function, AMDF)의 역수를 가중한 MCC (Modified Cross-Correlation)알고리즘을 제안한다. 모의신호를 사용한 수치 시뮬레이션 실험으로 종래의 AMDF, Cross-Correlation 알고리즘과 본 연구에서 제안한 MCC 알고리즘의 분해능을 비교 분석하였다 각 알고리즘의 TDE 결과에 대해 STFT(Short Time fourier Transform)에 의한 시간 주파수 해석을 한 결과 MCC알고리즘을 사용하여 TDE 분해능이 향상되었음을 보고한다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.12 no.2
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• pp.129-140
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• 1999

추계론적 해석은 구조계 내의 해석인수에 존재하는 공간적 또는 시간적 임의성이 구조계 반응에 미치는 영향에 대한 고찰을 목적으로 한다. 확률장은 구족계 내에서 특정한 확률분포를 가지는 것으로 가정된다. 구조계 반응에 대한 이들 확률장의 영향 평가를 위하여 통계학적 추계론적 해석과 비통계학적 추계론적 해석이 사용되고 있다. 본 연구에서는 비통계학적 추계론적 해석방법 중의 하나인 가중적분법을 제안하였다. 특히 구조계의 공간적 임의성이 큰 특성을 가지고 있는 반무한영역에 대한 적용 예를 제시하고자 한다. 반무한영역의 모델링에는 무한요소를 사용하였다. 제안된 방법에 의한 해석 결과는 통계학적 방법인 몬테카를로 방법에 의한 결과와 비교되었다. 제안된 가중적분법은 자기상관함수를 사용하여 확률장을 고려하므로 무한영역의 고려에 따른 해석의 모호성을 제거할 수 있다. 제안방법과 몬테카를로 방법에 의한 결과는 상호 잘 일치하였으며 공분산 및 표준편차는 무한요소의 적용에 의하여 매우 개선된 결과를 나타내었다.