• 한국정보처리학회논문지
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• 제4권12호
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• pp.3185-3199
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• 1997

본 논문에서는 블록 근사화식을 적응적으로 선택하여 프랙탈 계수를 결정함으로서 기존의 프랙탈 부호화 방법에서 문제가 되는 부호화 시간을 개선하는 방법과 복원 영상의 화질을 향상시킬 수 있는 방법을 제안한다. 첫 번째로 부호화 시간을 단축하기 위해 밝기값과 분산에 의해 특성이 결정된 Domain 블록을 선형 리스트로 구성한 후 l차 허용오차 임계치에 의해 블록 탐색 시간을 제어할 수 있게 하였다. 두 번째로 블록 분할 레벨을 3단계로 하여 부호화할 때 최저 분할 레벨의 Range 블록이 만족할 만한 근사화 오차를 갖는 Domain블록을 찾지 못하면 그 블록에 한하여 밝기항을 비선형 변환식으로 새로운 변환 계수를 결정하여 화질을 향상시켰다. 제안한 방법으로 실험한 결과 기존의 부호화 방식보다 부호화 시간은 2배이상 향상되었고 동일한 압축율에서 PSNR값은 1-2dB정도가 향상되었다.

• 대한전자공학회논문지SP
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• 제43권5호
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• pp.22-29
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• 2006

본 논문에서는 블록 기반 실시간 계수 시스템을 제안한다. 계수 시스템은 쇼핑몰이나 대형건물의 출입구, 엘리베이터, 에스컬레이터 등과 같은 다양한 환경에 적용될 수 있다. 본 논문의 핵심은 세 부분으로 구분 할 수 있다. 첫째, 환경 변화에 강인한 배경 제거 기법, 둘째, 학습을 이용한 블록 기반 계수 결정 방법, 마지막으로 4 채널에서 실시간으로 처리가 가능한 시스템 구현이다. 환경 변화에 강인한 배경 제거 기법으로 MOG(mixture of gaussian) 방법을 적용하였으며, 블록 기반 계수 결정 방법은 영상을 $6{\times}12$개의 영역으로 구분하고, 학습 영상을 이용하여 각각의 블록에서 물체의 크기에 대한 평균과 분산을 계산하고 이를 저장하여 계수에 적용하는 방법을 제안하였으며, 마지막으로 4 채널에서 실시간으로 처리 하기 위하여 추출된 물체 각각을 구분하여 추적하는 것이 아니라 물체가 이동 중에 발생할 수 있는 여러 상황 즉 결합이나 분리되는 현상을 분석하여 계수 판단에 적용하였다. 제안된 방법을 이용하여 에스컬레이터, 복도 그리고 출입문등과 같이 조명환경과 그림자 상황 등이 변하는 환경에서 의 계수 정확도는 $90{\sim}94%$, 채널 당 처리 속도는 15 frames/sec 이상의 성능을 보였다.

• 한국통신학회논문지
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• 제21권3호
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• pp.684-691
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• 1996

Since the period of a spreading code in DS/SS communication systems is generally long, it is necessary to make the code acquisition as fast as possible. The code acquisition time can be sued as a measure to evaluate the performance of code acquisition systems. The search rate of serial search codee acquisition system used in the coventional CDMA cellular system is lower than that of the matched filter technique. In order to reduce the code acquisition time, this paper proposes hybrid code acquisition system composed filters combined with serial search blocks. In the proposed system, the matched filter sweeps possible code phases fast and the acquired phase information is verified by the serial search block. The mean and the variance of its acquisition time are calculated and compared with those of double dwell serial search system. The results indicate better performance of the proposed system by yielding its small vaues of the mean and the variance of code acquisition time.

• Current Optics and Photonics
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• 제8권2호
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• pp.170-182
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• 2024

The dimensional accuracy and consistency of a dual oil circuit centrifugal fuel nozzle are important for fuel distribution and combustion efficiency in an engine combustion chamber. A point cloud measurement method was proposed to solve the geometric accuracy detection problem for the fuel nozzle. An improved variance focus measure operator was used to extract the depth point cloud. Compared with other traditional sharpness evaluation functions, the improved operator can generate the best evaluation curve, and has the least noise and the shortest calculation time. The experimental results of point cloud slicing measurement show that the best window size is 24 × 24 pixels. In the height measurement experiment of the standard sample block, the relative error is 2.32%, and in the fuel nozzle cone angle measurement experiment, the relative error is 2.46%, which can meet the high precision requirements of a dual oil circuit centrifugal fuel nozzle.

• 한국컴퓨터산업학회논문지
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• 제9권5호
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• pp.207-216
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• 2008

초장력 스프레드시트 기능의 엑셀 프로그램에서 자료를 통계적으로 분석하는 데이터분석 메뉴는 엑셀 2000 이후 수정 보완 되고 있지 않으며 그 활용도도 매우 저조하다. 본 연구에서는 엑셀 통계분석 메뉴 활용도 향상을 위하여 사용빈도가 높은 분산분석의 엑셀 메뉴 실행 결과와 계산식에 의한 이론 결과를 비교하고 고차원 분석 매크로를 개발하였다. 실자료를 엑셀 라이터분석 메뉴를 적용하여 얻은 결과와 계산식에 의한 이론 결과는 요인이 한개인 일원배치법이나 두개인 이원배치 법에서 모두 정확히 일치하였다. 즉 엑셀 데이터분석 메뉴의 신뢰성이 검증되었다. 고차원적인 분산분석법인 블록화된 분산분석 결과를 제공하는 매크로 및 일원분산분석법에서 평균 차이 있는 그룹들을 찾아내는 다중비교 분석방법 매크로를 엑셀 함수를 이용하여 개발하였다.

• International Journal of Contents
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• 제9권1호
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• pp.6-10
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• 2013

Foreground estimation in object segmentation has been an important issue for last few decades. In this paper we propose a GrabCut based automatic foreground estimation method using block clustering. GrabCut is one of popular algorithms for image segmentation in 2D image. However GrabCut is semi-automatic algorithm. So it requires the user input a rough boundary for foreground and background. Typically, the user draws a rectangle around the object of interest manually. The goal of proposed method is to generate an initial rectangle automatically. In order to create initial rectangle, we use Gabor filter and Saliency map and then we use 4 features (amount of area, variance, amount of class with boundary area, amount of class with saliency map) to categorize foreground and background. From the experimental results, our proposed algorithm can achieve satisfactory accuracy in object segmentation without any prior information by the user.

• 한국경영과학회지
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• 제10권1호
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• pp.9-13
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• 1985

This paper develops a decomposition method for stochastic programming with a block diagonal structure. Here we assume that the right-hand side random vector of each subproblem is differente each other. We first, transform this problem into a master problem, and subproblems in a similar way to Dantizig-Wolfe's Decomposition Princeple, and then solve this master problem by solving subproblems. When we solve a subproblem, we first transform this subproblem to a Deterministic Equivalent Programming (DEF). The form of DEF depends on the type of the random vector of the subproblem. We found the subproblem with finite discrete random vector can be transformed into alinear programming, that with continuous random vector into a convex quadratic programming, and that with random vector of unknown distribution and known mean and variance into a convex nonlinear programming, but the master problem is always a linear programming.

• 대한기계학회논문집
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• 제18권2호
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• pp.372-379
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• 1994

In this study, the describing function is adopted to represent nonlinearity in the system equations. The compliance can be obtained by solving nonlinear simultaneous algebraic quations for multi-degrees-of-freedom system with multinonlinearities. When the technique is applied, the nonlinearity of the system can be identified from the compliance which is obtained from the sinusoidal excitation of the system. By employing the describing function in the Building Block Analysis, we can extensively develop the BBA into investigation of the continuous systems with nonlinearities. The evaluated compliance can quantitatively show the effects of nonlinearity such as the transfer of the natural frequency, the variance of the compliance at the natural frequency, and the jump phenomena which occur during sweeping of the excitation frequency.

• 한국자원식물학회지
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• 제19권6호
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• pp.677-679
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• 2006

The objectives of this study were to examine the genetic variation of 20-year-old tree height and to estimate heritabilities and genetic gains of Korean white pine. Analysis of variance showed that families and family x block interaction had the significant (p=0.01) effects on tree height. However, family variation appears to be much greater than the variation due to family x block interaction. Individual tree heritability was higher ($h_I^2=0.73$) than family heritability, ($h_F^2=0.83$) therefore, combined selection showed the largest genetic gain (17.76%) in a given equal intensity of selection.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -2
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• pp.1228-1231
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• 2002

Digital image watermarking scheme using adaptive block division is proposed. To increase the perceptual invisibility, the image is divided into blocks by local properties and the human visual system (HVS), then the significant blocks are selected in the divided blocks. The significant coefficient is determined by Weber's law in these blocks. To increase the robustness, low frequency domains of the discrete cosine transform (DCT) and the discrete wavelet transform (DWT) are used. The watermark is embedded into the selected significant blocks of the DCT's and DWT's low frequency domains with adaptive watermark strengths. The watermark strength is determined by the variance and the local properties of the significant block. The experimental results prove that the proposed scheme has a good robustness against several image processing operations (e.g. median filtering, cropping, scaling, JPEG, JPEG2000, etc.) without significant degradation of the watermarked image.