• 한국통신학회논문지
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• 제22권4호
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• pp.675-684
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• 1997

The bit rate control algorithm which is capable of handing scene change is proposed. In MPEG-2 TM5, block variance is used to measure block activity. But block variance is not consistent with human visual system and does not differenciate the distribution of pixel values within the block. In target bit allocation process of TM5, global complexity, obtained by results of previous coded pictures, is used. Since I pictures are spaced relatively far apart, their complexity estimate is not very accurate. In the proposed algorithm local variance is used to measure block activity and detect scene change. Local variance, using deviation from the mean of neighboring pixels, well represents the distribution of pixel values within the block. If scene change is detected, the local variance information is used for target bit allocation process. Allocating target bits for I picture, the average local variance difference between previous and current I picture is considered. The experimental results show that the proposed algorithm can detect scene change very precisely and gives better picture quality and higher PSNR values than MPEG-2 TM5.

• 한국멀티미디어학회논문지
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• 제8권3호
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• pp.313-321
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• 2005

연속 계조 영상을 이진 영상으로 변환하는 방법을 해프토닝이라 한다. 이와 같은 해프토닝 방법 중 오차확산법은 연속 계조 영상을 이진 영상으로 표현할 때 우수한 화질을 보이지만 에지 영역에서는 에지 정보가 흐려지는 특성이 있다. 이를 개선하기 위해 원영상의 국부적인 공간 정보를 이용하여 에지를 강조하는 방법을 제안한다 제안 방법은 인간의 시각이 한 점을 인식하지 않고 국부 평균을 인식함을 고려하여 한 화소와 인접 화소의 평균을 이용한 비율 값을 국부 평균에 가중치로 적용하고 에지 강조 정보량(EEI : Edge enhancement information)을 구한다. 이때 국부 평균에 적용되는 가중치는 원 화소와 3$\times$3 블록의 평균과의 차이 값과 공간 활성도(LAM : Local activity measure)의 비율을 이용하여 계산된다 공간 활성도는 국부 공간의 변화량을 표현하는 척도로 3$\times$3 블록의 평균과 블록의 화소의 차이 값의 제곱의 합으로 구한다 EEI를 양자화기 입력에 더하여 해프톤 영상의 에지를 강조한다. 제안 방법의 성능은 에지 상관도 평가 함수로 평가했으며 제안 방법을 영상에 적용한 결과 이진 영상의 에지가 강조되어 시각적으로 선명한 결과를 보이며 미세한 에지도 잘 보존되었다. 또한 눈에 거슬리는 규칙적 패턴도 줄어 개선된 화질을 보여주었다.

• 전자공학회논문지B
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• 제33B권4호
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• pp.101-110
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• 1996

Color image quantization is a process of selecting a set of colors to display an image with some representative colors without noticeable perceived difference. It is very important in many applications to display a true color image in a low cost color monitor or printer. the basic problem is how to display 224 colors with 256 or less colors, called color palette. In this paper, we propose an algorithm to design the 256 or less size color palette by using spatial maskin geffect of HVS and subjective distortion measure weighted by color palette by using spatial masking effect of HVS and subjective distortion measure weighted by color activity in 4*4 local region in any color image. The proposed algorithm consists of octal prequantization and subdivision quantization processing step using the distortion measure and modified Otsu's between class variance maximization method. The experimental results show that the proposed algorithm has higher visual quality and needs less consuming time than conventional algorithms.

• 천문학회지
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• 제29권spc1호
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• pp.323-324
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• 1996

In the present work we introduce a new flare activity indicator, MAD and examine its characteristics by analyzing a set of successive three days' observations of a typical active region, AR2372. The computed MAD is compared with conventional activity indicator such as separator. It is found that. (1) MAD traces very well the separator, (2) it. singles out. local discontinuity of magnetic field lines and (3) it. is a good measure of describing the evolutionary status of active region.

• 한국통신학회논문지
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• 제21권4호
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• pp.848-854
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• 1996

Many image display devices allow only a limited number of colors to be simultaneously displayed. in disphaying of natural color image using color palette, it is necessary to construct an optimal color palette and the optimal mapping of each pixed of the original image to a color from the palette. In this paper, we proposed the clustering algorithm using local region block centered one color cluster in the prequantized 3-D histogram. Cluster pairs which have the least distortion error are merged by considering distortion measure. The clustering process is continued until to obtain the desired number of colors. The same as the clustering process, original color value. The proposed algorithm incroporated with a spatial activity weighting value which is reflected sensitivity of HVS quantization errors in smoothing region. This method produces high quality display images and considerably reduces computation time.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 1995년도 학술대회
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• pp.83-86
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• 1995

Many image display devices allow only a limited number of colors to be simultaneously displayed. In displaying of natural color image using color palette, it is necessary to construct an optimal color palette and map each pixel of the original image to a color palette with fast. In this paper, we proposed the clustering algorithm using local region block centered one color cluster in the prequantized 3-D histogram. Cluster pairs which have the least distortion error are merged by considering distortion measure. The clustering process is continued until to obtain the desired number of colors. Same as the clustering process, original color image is mapped to palette color via a local region block centering around prequantized original color value. The proposed algorithm incorporated with a spatial activity weighting value which is smoothing region. The method produces high quality display images and considerably reduces computation time.

• 대한전자공학회논문지SP
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• 제42권3호
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• pp.107-114
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• 2005

선으로 구성된 회로도나 설계도 같은 특수 목적 영상을 처리할 경우 에지가 강조된 영상을 필요로 한다. 또한 프린터, 팩시밀리, LCD TV 등과 같은 이진 출력 장치에 연속 계조 영상을 표현하기 위한 디지털 해프토닝 방법 중 오차 확산 방법으로 이진 영상을 생성할 경우 에지가 흐려진다. 본 논문은 회로도나 설계도 등의 영상 뿐 아니라 이진 출력 장치 등에 사용되는 이진 영상의 에지를 강조하는 방법을 제안한다. 인간의 눈은 한 화소의 명암값이 아니라 국부 평균을 인식한다는 것을 이용하여 제안 방법은 원화소의 명암값과 $3{\times}3$ 블록의 평균 명암값과의 차이 값에 공간적 위치 값에 따른 가중치를 결합하여 국부 공간 변화량(LAM: local activity measure)을 사용한다. 제안된 시스템은 또한 LAM에 평균 명암도를 곱하여 얻어진 에지 강조 정보량(IEE: information of edge enhancement)을 사용한다. IEE를 양자화기 입력에 더하여 이진 영상의 에지를 강조한다. 컴퓨터 시뮬레이션은 제안 방법이 기존의 방법에 비해 영상의 에지가 강조되어 시각적으로 선명한 영상을 생성한다. 또한 거리에 따른 에지 상관도와 로컬 평균 일치도를 이용하여 제안 방법과 기존 방법의 특성을 분석한다.

• 천문학회보
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• 제46권1호
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• pp.54.1-54.1
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• 2021

Observing sub-mm continuum emission from cold dust can play an important role in measuring star formation rates of galaxies, especially in the case of AGN host ones, since AGNs contaminate FIR fluxes by dust heating. To measure star formation rates, we observed total 49 local AGN host galaxies(z<0.2) by SCUBA-2 camera at James Clerk Maxwell Telescope(JCMT) at 450㎛ and 850㎛. We performed several tests with the observed images to determine whether each source is detected, and adopted 3s as the flux upper limit in non-detection cases. Using these measurements and FIR archival data, we modeled spectral energy distributions of the galaxies to estimate star formation rates. The effect of AGN activity on host galaxy star formation will be discussed.

• 대한인간공학회지
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• 제24권4호
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• pp.55-62
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• 2005

This study examined the effect of ergonomic heel rest that was designed for drivers who have physical handicap in the low leg muscles or have to drive prolonged hours with frequent foot pedaling. An experiment was designed to test the ergonomic heel rest with traditional foot pedal. Forty subjects participated in the experiment. Electromyography(EMG) was used to monitor the muscle activity and fatigue of right leg, and Electro-goniometer was used to measure the ranges of motions of the knee and ankle. A simulator of driver's seat was built for the experiment and the heel rest was installed on it. In order to examine the low muscle activity and range of motion, subjects used the foot pedal for 15 minutes repetitively for each experimental condition. Another 15 minutes test without the heel rest was also performed for comparison. The Root Mean Square(RMS) and Mean Power Frequency(MPF) Shift were used to quantify the level of muscle activity and local muscle fatigue. In results, statistically significant decreases of muscle activity and fatigue were found in all the low leg muscles. The range of motion of the knee and ankle joint also decreased when the heel rest was used. The mechanism of the heel rest effect was discussed in this study. This type of heel rest can be applied to real driving situation after ensuring the safety, or overcoming the psychological discomfort possibly due to unfamiliarity.

• 대한산업공학회지
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• 제40권1호
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• pp.60-83
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• 2014

This paper aims to propose a research framework of analyzing voting activities of a national assembly on the basis of member-level voting similarity and provides a case study in the $18^{th}$ national assembly in South Korea. First, we propose a bill contentiousness measure that gives a higher score to bills for which ayes and noes are more diversified in both conservative and progressive parties. Based on the bill contentiousness measure, the top 5%, 10%, and 20% bills were identified and used for further analyses. Moreover, we propose a member-level voting similarity measure that compensates for the lower frequency of noes, and evaluate the pair-wise voting similarities for all lawmakers. Then, voting similarity differences to the affiliated/non-affiliated parties were analyzed for the members in the two major parties according to some internal/external key factors. Finally, similar voting groups were identified and their affiliations were investigated based on the multi-dimensional scaling (MDS) and network analysis techniques. A case study on the $18^{th}$ national assembly of South Korea showed that the cohesion of the members in the 'Hanara' party becomes higher than that of the 'Minju' party as the bill contentiousness increases, whereas the number of elected, local constituency versus proportional representation, and the competition intensity in a local constituency were found to be partially influential to the voting activities of lawmakers. In addition, MDS and network analysis showed that there is a distinctive difference between two parties when all bills are analyzed, whereas the diversity of parties increases in the same group as the bill contentiousness increases.