• Journal of Satellite, Information and Communications
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• v.9 no.2
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• pp.110-113
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• 2014

In this paper, we address a problem of finding the optimum inner and outer code rates for a concatenated code in Gaussian binary symmetric channels. Clearly, as the inner code rate decreases, the error detection capability of the inner code increases. However, decreasing the inner code rate implies a decrease in error-correction capability of the outer code when overall code rate is fixed. With this notion in mind, we examine the optimum distribution of redundancy on the outer and inner codes to achieve a maximum performance gain in the concatenated coding scheme. Our analysis shows that the maximum coding gain can be obtained when the inner code rate is maximized and the outer code rate is minimized under the constraint of total code rate is fixed.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2010.11a
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• pp.175-177
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• 2010

본 논문에서는 MPEG 의 3차원 비디오 시스템의 표준 깊이정보 맵에 대한 효율적인 부호화를 위하여 전처리 방법을 제안한다. 현재 3차원 비디오 부호화(3DVC)에 대한 표준화가 진행 중에 있지만 아직 깊이정보 맵의 부호화 방법에 대한 표준이 확정되지 않은 상태이다. 제안하는 기법에서는 우선, 입력된 깊이정보 맵에 대하여 원래의 히스토그램 분포를 가우시안 혼합모델(GMM)기반의 EM 군집화 기법에 의한 방법으로 분리 후, 분리된 히스토그램을 기반으로 깊이정보 맵을 여러 개의 영상으로 분리한다. 그 후 분리된 각각의 영상을 배경과 객체에 따라 다른 조건의 mean shift filter로 필터링한다. 결과적으로 영상내의 각 영역 경계는 최대한 살리면서 영역내의 화소 값에 대해서는 평균 연산을 취하여 부호화시 효율을 극대화 하고자 하였다. 실험조건은 $1024{\times}768$ 영상에 대해서 50 프레임으로 H.264/AVC base 프로파일로 부호화를 진행하였다. 최종 실험결과 bit rate는 대략 23% ~ 26% 정도 감소하고 부호화 시간도 다소 줄어드는 것을 확인 할 수 있었다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.4
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• pp.917-921
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• 2013

This paper have analyzed the change of breakdown voltage for conduction path of double gate(DG) MOSFET. The low breakdown voltage among the short channel effects of DGMOSFET have become obstacles of device operation. The analytical solution of Poisson's equation have been used to analyze the breakdown voltage, and Gaussian function been used as carrier distribution to analyze closely for experimental results. The change of breakdown voltages for conduction path have been analyzed for device parameters such as channel length, channel thickness, gate oxide thickness and doping concentration. Since this potential model has been verified in the previous papers, we have used this model to analyze the breakdown voltage. Resultly, we know the breakdown voltage is greatly influenced on the change of conduction path for device parameters of DGMOSFET.

• The Journal of the Acoustical Society of Korea
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• v.32 no.2
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• pp.131-137
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• 2013

In this paper we propose an improved voice activity detection (VAD) algorithm using statistical models in the signal subspace domain. A uncorrelated signal subspace is generated using embedded prewhitening technique and the statistical characteristics of the noisy speech and noise are investigated in this domain. According to the characteristics of the signals in the signal subspace, a new statistical VAD method using GGD (Generalized Gaussian Distribution) is proposed. Experimental results show that the proposed GGD-based approach outperforms the Gaussian-based signal subspace method at 0-15 dB SNR simulation conditions.

• Korean Journal of Optics and Photonics
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• v.35 no.4
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• pp.150-156
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• 2024

One of the key factors in research regarding long-distance laser beam propagation, as in free-space optical communication or laser power transmission, is the transmission efficiency of the laser beam. As a way to improve efficiency, we perform extensive numerical simulations of the effect of modifying the laser beam's profile, especially replacing the fundamental Gaussian beam with a super-Gaussian beam. Numerical simulations of the transmitted power in the ideal diffraction-limited beam diameter determined by the optical system of the transmitter, after about 1-km propagation, reveal that the second-order super-Gaussian beam can yield superior performance to that of the fundamental Gaussian beam, in both single-channel and coherently combined multi-channel laser transmitters. The improvement of the transmission efficiency for a 1-km propagation distance when using a second-order super-Gaussian beam, in comparison with a fundamental Gaussian beam, is estimated at over 1.2% in the singlechannel laser transmitter, and over 4.2% and over 4.6% in coherently combined 3- and 7-channel laser transmitters, respectively. For a range of the propagation distance varying from 750 to 1,250 m, the improvement in transmission efficiency by use of the second-order super-Gaussian beam is estimated at over 1.2% in the single-channel laser transmitter, and over 4.1% and over 4.0% in the coherently combined 3- and 7-channel laser transmitters, respectively. These simulation results will pave the way for future advances in the generation of higher-order super-Gaussian beams and the development of long-distance optical energy-transfer technology.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.8
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• pp.1132-1140
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• 2011

When the offshore wind power plant is planned to construct, it is important for the wind farm site to figure out the distribution of the weak soil layers that might cause subsidence by the impact of the external moment from the wind plant's load and an oscillating wind load. Coring test is the optimistic method to figure out weak soil layers, but this method have some problem such as condition of the in-situ or economical limitation. In order to make up for the weak points in coring test, the researches using the geostatistics methods is actually done. In this study, setting a fixed coastal area that offshore wind plants construct firstly and Estimation of distribution on the thickness of the weak soil layer through the geostatistic method is conducted. The weak soil layer is sorted by result of the Standard penetration test, geostatistic method is used to ordinary kring and sequential gaussian simulation and compared to both method's result. As a results of study, we found that both methods show similar estimations of deep weak soil layer and we could evaluate quantitatively the uncertainty of the result.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.6
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• pp.1260-1265
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• 2012

This paper have presented the change for subthreshold characteristics for double gate(DG) MOSFET based on scaling theory and the shape of Gaussian function. To obtain the analytical solution of Poisson's equation, Gaussian function been used as carrier distribution and consequently potential distributions have been analyzed closely for experimental results, and the subthreshold characteristics have been analyzed for the shape parameters of Gaussian function such as projected range and standard projected deviation. Since this potential model has been verified in the previous papers, we have used this model to analyze the subthreshold chatacteristics. The scaling theory is to sustain constant outputs for the change of device parameters. As a result to apply the scaling theory for DGMOSFET, we know the subthreshold characteristics have been greatly changed, and the change of threshold voltage is bigger relatively.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.1
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• pp.37-41
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• 2014

Recently, a lot of research efforts has been directed toward spectrum sensing techniques exploiting the some characteristics of power spectrum. Among them, a sensing technique employing the maximum of power spectrum as a test statistic has appeared in the literature and its false alarm probability was also derived under the assumption that the test statistic follows the Gaussian distribution. This paper provides an exact form of the false alarm probability without using the assumption and compares it with the previous work.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06b
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• pp.396-398
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• 2012

대부분의 실세계 데이터는 시간성을 띄고 있으므로 시간성을 지닌 데이터를 분석할 수 있는 기계 학습 방법론은 매우 중요하다. 이런 관점에서 비디오 데이터는 다양한 모달리티가 결합된 대표적인 시간 데이터 이므로 비디오 데이터를 대상으로 하는 기계 학습 방법은 큰 의미를 갖는다. 본 논문에서는 음성 채널에기반한 비디오 데이터 분석 방법의 예비 연구로 비디오 데이터에 등장하는 화자를 인식할 수 있는 간단한 방법을 소개한다. 제안 방법은 MFCC (Mel-frequency cepstrum coefficients)를 이용하여 인간 음성 특성의 분포를 분석한 후 분석 결과를 신경망에 입력하여 목표한 화자를 인식하는 복합 신경망 모델을 특징으로 한다. 실제 TV 드라마 데이터에서 가우시안 혼합모델, 가우시안 혼합 신경망 모델, 제안 방법의 화자 인식 성능을 비교한 결과 제안 방법이 가장 우수한 인식 성능을 보임을 확인하였다.

• Proceedings of the Korean Information Science Society Conference
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• 2005.07b
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• pp.619-621
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• 2005

은닉 마코프 모델은 이산 동역학을 표현할 수 있는 확률 모형이다. 우도 함수 최적화를 수행하는 전통적인 Baum-Welch 학습 알고리즘은 국소해로 수령하기 쉬우며, 우도함수의 특성상 복잡한 모델을 선호하는 바이어스가 존재한다. 베이지안 프레임워크에서는 파라미터를 랜덤 변수로 보고 이에 대한 사후 확률 분포를 추정하여 이 문제를 해결할 수 있다. 본 논문에서는 베이지안 추정을 위한 결정론적 근사화 기법인 변분 베이지안 방법을 이용, 출력 노드에 가우시안 혼합 노드를 지니는 일반화된 HMM의 추론 방법을 유도한다. 인공 데이터에 대한 실험을 통해, 본 방법이 효과적인 HMM 학습을 수행할 수 있음을 보인다.