• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2012.11a
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• pp.125-128
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• 2012

이 논문에서는 향상된 움직임 적응적 디인터레이싱 알고리듬을 제안한다. 정확한 움직임 정보탐색을 위하여 Modified Edgd-based Line Average(MELA)기법, 연속된 5개의 필드에서의 움직임 탐색, 블록기반의 지역적 특성을 포함한다. 움직임 검출부분에서는 FIR필터를 이용한다. 이것은 물체의 움직임의 내부를 정확하게 탐색 할 뿐만 아니라, 영상에 포함된 잡음도 줄일수 있는 향상된 기법을 이용함으로서 계산 할 수 있다. 검출된 움직임의 정도에 따라서 가중치를 구하여 공간적 기법과 시간적 기법을 결합 시킨다. 제안된 방법의 영상 시퀀스에 대한 실험 결과는 기존의 방법들에 비하여 주관적, 객관적인 비교에서 우수함을 보여준다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2012.07a
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• pp.405-406
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• 2012

본 논문에서는 H.264 부호기의 복잡도를 낮추기 위한 고속 움직임 탐색 기법을 제안한다. H.264 부호기는 움직임 탐색 알고리즘 및 다양한 모드 결정으로 인해 매우 높은 복잡도를 갖기 때문에 고해상도 영상의 압축에 시간적 부담을 준다. 따라서, 우리는 비디오 프레임에 계층적으로 양자화를 적용한 뒤, 각 단계마다 움직임 탐색 영역을 적절히 분배함으로써 최적의 움직임 벡터를 예측하는 기법을 제시한다. 제안 기법은 H.264 부호기의 한가지 예측 모듈로 제안되며, 부가적으로 움직임 벡터 예측자 주변을 탐색하는 모듈이 수행된다. 실험 결과에서 제안 알고리즘이 기존의 H.264 부호기에 비해 매우 빠르면서 안정된 비트율-왜곡 성능을 가짐을 보인다.

• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.325-326
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• 2007

본 논문에서는 H.264 동영상 표준 부호화 방식의 움직임 추정을 위한 고속 다중 참조 프레임 선택 기법에 대해 제안한다. 다중 참조 프레임에 대한 움직임 추정 수행 시 참조 프레임 수에 비례하여 계산량이 증가하는 반면에 동영상의 특성에 따라 부호화 효율의 이득없이 계산량만을 소비하는 경우가 발생된다. 따라서 본 논문에서는 각 참조 프레임에서의 움직임 추정에 대한 SAD값의 비교를 통해 다중 참조 프레임 움직임 추정의 종료 시점을 적응적으로 결정한다 실험 결과를 통해 5개의 참조프레임 사용을 기준으로 제안된 기법을 사용하였을 때 움직임 추정에 소요되는 시간은 가용한 모든 참조 프레임에 대해 움직임 추정을 수행하는 방식 대비 평균 50%정도 감소하였으며, PSNR 및 발생 비트율 측면에서 거의 동일한 성능을 유지함을 확인할 수 있었다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.2
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• pp.438-446
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• 2013

Generally, a camera isn't located at the center of display in a tele-presence system and it causes an incorrect eye contact between speakers which reduce the realistic feeling during the conversation. To solve this incorrect eye contact problem, we newly propose an intermediate view reconstruction algorithm using both a color camera and a depth camera and applying for the depth image based rendering (DIBR) algorithm. In the proposed algorithm, an efficient hole filling method using the arithmetic mean value of neighbor pixels and an efficient boundary noise removal method by expanding the edge region of depth image are included. We show that the generated eye-contacted image has good quality through experiments.

• The Korean Journal of Nuclear Medicine Technology
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• v.21 no.2
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• pp.80-85
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• 2017

Purpose The D530c have cadmium zinc telluride(CZT) detectors that are arranged focus on the heart. This structural characteristic allows for quicker imaging without rotation, but this is sensitive to patient movement and can affect the test results. The aim of this study is to optimize the image quality by reducing patient movement during the examination. Materials and Methods We analyzed the patients' movements, and performed various activities such as provided patient education about correct breathing techniques and avoiding patient movements, and created breathing correction tools to minimize patient movement during exam. The 70 patients who underwent myocardial perfusion SPECT with D530c in November 2016 were categorized as the group before the corrective steps. Another 70 patients who underwent the procedure with D530c from February 14, 2017 to February 21, 2017 were categorized as the improvement group. Images acquired during stress and at rest were compared and analyzed by measuring the durations of heart movements over certain distances (4 mm, 8 mm, 12 mm, or more) noted on the x-, y-, and zaxes. Results After the activities, the durations of heart movements decreased in the images acquired both under stress and at rest. In particular, there were no large motions greater than 12 mm recorded in the stress images after the improvement. There was a significant difference (p<0.005) in the 4-mm and 8-mm fluctuations on the X-axis and the 8-mm fluctuations on the Z axis in the stress images, but there was no significant difference (p>0.005) in the other stress and rest intervals. Conclusion The decrease in the time of motion occurrence due to the 4 mm fluctuation distance that can occur through breathing can be understood as a result of the breathing being corrected through training and motion prevention tools. It is expected that the image quality will be improved by reducing the occurrence time according to the variation distance of 8 mm or 12 mm, which is expected as the actual movement of the patient other than the breathing.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.9A
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• pp.1411-1418
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• 1999

In this paper, we propose a fast motion estimation algorithm using motion prediction and neural network. Considering that the motion vectors have high spatial correlation, the motion vector of current block is predicted by those of neighboring blocks. The codebook of motion vector is designed by Kohonen self-organizing feature map(KSFM) learning algorithm which has a fast learning speed and 2-D adaptive chararteristics. Since the similar codevectors are closely located in the 2-D codebook the motion is progressively estimated from the predicted codevector in the codebook. Computer simulation results show that the proposed method has a good performance with reduced computational complexity.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.38 no.3
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• pp.22-22
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• 2001

정보량이 많은 고화질의 동영상을 실시간으로 전송하기 위하여 압축 알고리즘을 필수적으로 사용하고 있으며, 시간적 중복성을 제거하는 동영상의 압축방법은 움직임 추정 알고리즘을 사용한다. 본 연구에서 설계하고자 하는 움직임 추정기는 블록정합 알고리즘이며, MPEG 부호기에서 사용되는 DCT 연산 결과인 DC 값을 이용하여 화면의 밝기를 판단한다. 움직임 추정기는 휘도 신호 8비트 모두를 사용하지 않고, 화면 밝기에 따른 비트 플레인(bit plane)에서 3비트만 선택하는 비교선택기를 이용한다. 본 연구에서 제안한 비교 선택기는 I-Picture만을 계산한다. I-Picture에 의해 계산된 선택 비트는 I, P와 B Picture의 움직임 추정 연산에 사용함으로서 움직임 추정기의 크기를 줄일 수 있는 구조를 제안하였다. 제안된 움직임 추정기의 고찰을 위하여 실험에 사용된 표준 동영상의 해상도는 352×288이며, DCT 연산의 처리 블록은 8×8이며, 탐색 영역은 23×23이다. 제안된 알고리즘은 C언어로 모델링하였으며, 기존 완전탐색방법과 PSNR을 비교한 결과 사람의 시각으로 거의 구별할 수 없는 작은 차이(0～0.83dB)가 나타남을 알 수 있었다. 본 연구에서 제안한 움직임 추정기의 하드웨어 크기는 기존 구조Ⅰ보다 38.3%, 기존 구조Ⅱ보다 30.7% 줄일 수 있었고, 메모리 크기는 기존 구조Ⅰ,Ⅱ보다 31.3% 줄일 수 있었다.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.44 no.3
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• pp.16-22
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• 2007

Motion Estimation time in the H.264 has a large portion of encoding time and must be improved for real time application. Most of proposed motion estimation algorithm including Sub-pixel search use the fast search algorithm to speed up motion estimation by targeting the performance of full search in the reference code. This paper proposes a novel fast sub-pixel search control algorithm for H.264 encoder by using neighbor motion vector after analyzing the encoded Motion vector of video sequence. In addition the horizontal/vertical searching method is proposed with the horizontal/vertical directionality of motion vector. And the evaluation is performed with the proposed algorithms and other reference algorithms.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.10C
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• pp.1000-1010
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• 2006

This paper proposes a new architecture for DCT-based motion estimation and compensation. Previous methods do riot take sufficient advantage of the sparseness of 2-D DCT coefficients to reduce execution time. We first derive a recursion equation to perform DCT domain motion estimation more efficiently; we then use it to develop a wavefront array processor (WAP) consisting of processing elements. In addition, we show that the recursion equation enables motion predicted images with different frequency bands, for example, from the images with low frequency components to the images with low and high frequency components. The wavefront way Processor can reconfigure to different motion estimation algorithms, such as logarithmic search and three step search, without architectural modifications. These properties can be effectively used to reduce the energy required for video encoding and decoding. The proposed WAP architecture achieves a significant reduction in computational complexity and processing time. It is also shown that the motion estimation algorithm in the transform domain using SAD (Sum of Absolute Differences) matching criterion maximizes PSNR and the compression ratio for the practical video coding applications when compared to tile motion estimation algorithm in the spatial domain using either SAD or SSD.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.12C
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• pp.1669-1676
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• 2004

In H.264, 7 modes {16${\times}$16, 16${\times}$8, 8${\times}$16, 8${\times}$8, 8${\times}$4, 4${\times}$8, 4${\times}$4) are used to enhance the coding efficiency. The motion vector estimation with 7 modes may require huge computing time. In this paper, to speed up the motion vector estimation procedure while the high image quality remains, we propose a motion vector refinement scheme using the temporary motion vector generated with little computation. The proposed estimation process consists of three phases: Mode decision for a 16${\times}$16 macroblock, Composing a temporary motion vector, Refinement of the temporary motion vector. We demonstrate the effectiveness of the proposed method by computer simulation. In the results, the encoding time consumed by the proposed scheme has been reduced significantly while the encoded video quality remains unchanged.