• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.6
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• pp.1116-1121
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• 2006

We studied on some techniques which are able to discriminate the difference between normal and infarcted myocardium by consecutive image analysis in B-mode echocardiogram. In order to analyze two-dimensional echocardiogram, we presented inter-frame and intra-frame analysis method throughout the complete heart cycle in closed-chest human and proposed new analysis parameters which are named HGE and LT. The analysis technique using the proposed parameters revealed quantitatively dominant features between normal and infarcted regions. The infarcted areas yield regions of higher intensity throughout the entire cardiac cycle, but normal tissue demonstrates greater variability throughout the entire cardiac cycle. Hence, we could verify that these parameters varying over the entire cardiac cycle are good indicators for the state of myocardium.

• ETRI Journal
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• v.29 no.3
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• pp.390-392
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• 2007

In this paper, we propose a new error concealment (EC) method using inter-layer correlation for scalable video coding. In the proposed method, the auxiliary motion vector (MV) and the auxiliary mode number (MN) of intra prediction are interleaved into the bitstream to recover the corrupted frame. In order to reduce the bit rate, the proposed method encodes the difference between the original and the predicted values of the MV and MN instead of the original values. Experimental results show that the proposed EC outperforms the conventional EC by 2.8 dB to 6.7 dB.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.90-93
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• 2002

In this work, an efficient lifting implementation of invertible deinterlacing is proposed. The invertible deinterlacing is a technique developed for intra-frame-based video coding as a preprocessing. Unlike the conventional deinterlacing, it preserves the sampling density and has the invertibility. For a special selection of filters, it is shown that the deinterlacing can be implemented efficiently by an in-place computation. It is also shown that the deinterlacing can be combined with the lifting discrete wavelet transform (BWT) employed in JPEG2000. A bit modification of the original lifting DWT is shown to provide the simultaneous implementation of deinterlacing. This fact makes the proposed technique attractive for the application to Motion-JPEG2000. The inverse transform and the reversible lifting implementation are also discussed.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2013.06a
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• pp.278-279
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• 2013

최근에 완료된 HEVC(High Efficiency Video Coding) 비디오 압축 표준은 H.264/AVC에 비해 2배 이상 향상된 압축 효율을 제공한다. 현재 진행 중인 HEVC 확장 (extension) 작업에서는 손실 및 무손실 부호화에서 4:2:2 및 4:4:4 색차 포맷과 최대 12비트 깊이를 지원하는 고급 프로파일을 개발하고 있다. 현재까지 개발된 HEVC의 CABAC(Context-based Adaptive Binary Arithmetic Coding)은 손실 부호화 환경에 적합하게 설계되었기 때문에 무손실 부호화 환경에서 최적의 부호화 성능을 제공하지 못한다. 본 논문에서는 4:4:4 색차 포맷 영상의 무손실 화면내 부호화 환경에서 잔여 신호의 통계적 특성을 고려한 향상된 CABAC 잔여 데이터 부호화 방법을 제안한다. 실험 결과를 통해, 본 논문에서 제안하는 향상된 CABAC 방법이 무손실 화면내 부호화에서 기존의 CABAC 방법에 비해 평균 약 2.41% 의 비트 수를 감소시키는 것을 확인했다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2015.07a
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• pp.40-42
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• 2015

최근 UHD TV 시장이 커지면서 이에 따라 4K 이상의 해상도에 대응하는 코덱의 필요성이 증가하였다. 2013년 1월 차세대 동영상 압축 기술인 HEVC (High Efficiency Video Coding)가 제정되면서 초고해상도 동영상에 대응이 가능해졌다. 새로운 동영상 압축 기술이 제정되면서 초고해상도 동영상에서도 워터마킹의 필요성이 증대되었다. 본 논문에서는 PU 크기와 모드의 상관관계를 이용하여 압축 시 인트라 프레임에서 워터마킹 삽입영역을 제시한다. 또한 이를 바탕으로 간단한 워터마킹 삽입 방법 알고리즘을 소개한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.377-380
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• 2007

본 논문은 에러블록에 대해 인트라 프레임 예측모드를 이용하여 효율적인 공간적 에러 은닉 방법을 제안한다. 먼저, 에러블록내 픽셀값 복원을 위한 에러블록의 에지방향 예측은 주변 블록의 변환영역 예측모드를 이용한다. 예측된 에러블록의 정확한 에지방향은 인접한 두 에지방향과 비교하여 결정한다. 에러블록의 에지방향 예측을 주변블록의 예측모드를 이용함으로써, 기존의 에지방향 계산을 단축시킴으로써 효율적인 에러 은닉을 가능하게 한다

• Korea-Australia Rheology Journal
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• v.21 no.1
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• pp.71-79
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• 2009

The incomplete saturation and the void formation during the resin infiltration into fibrous porous media in the resin transfer molding process cause failure in the final product during its service. In order to better understand flow behavior during the filling process, a finite-element scheme for transient flow simulation across the micro-structured fibrous media is developed in the present work. A volume-of- fluid (VOF) method has been incorporated in the Eulerian frame to capture the evolution of flow front and the vertical periodic boundary condition has been combined to avoid unwanted wall effect. In the microscale simulation, we investigated the transient filling process in various fiber structures and discussed the mechanism leading to the flow fingering in the case of random fiber distribution. Effects of the filling pressure, the shear-thinning behavior of fluid and the volume fraction on the flow front have been investigated for both intra-tow and the inter-tow flows in dual-scale fiber tow models.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.286-289
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• 2006

Temporal dual gamma drive technology employing the 120Hz refresh rate was developed to enhance the off-axis viewing quality in patterned vertical alignment mode. The color shift ${\Delta}u'v'$ from on-axis to off-axis (60 deg.) for pale orange color, (R,G,B) = (196,124,96), was below 0.01, and the power exponent of gamma curve for off-axis viewing angle (60 deg.) was about 1.8, when the gamma curve for on-axis was set with power exponent of 2.4. The off-axis image distortion index was below 0.180 in contrast to the normal case ${\sim}0.23$. To elevate the response speed of liquid crystal in the intra-frame, the voltage below threshold voltage of liquid crystals was used.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.4A
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• pp.426-433
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• 2008

In this paper, we present a method to improve the performance of the four transmit antenna quasi-orthogonal space-time block code (STBC) in the coded system. For the four transmit antenna case, the quasi-orthogonal STBC consists of two symbol groups which are orthogonal to each other, but intra group symbols are not. In uncoded system with the matched filter detection, constellation rotation can improve the performance. However, in coded systems, its gain is absorbed by the coding gain especially for lower rate code. We propose an iterative decoding method to improve the performance of quasi-orthogonal codes in coded systems. With conventional quasi-orthogonal STBC detection, the joint ML detection can be improved by iterative processing between the demapper and the decoder. Simulation results shows that the performance improvement is about 2dB at 1% frame error rate.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1997.06a
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• pp.37-42
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• 1997

This paper describes two different S/W-based video codec systems. One is a frame-based video codec with fixed structure based on ITU H.263 standard and the other an object-based video codec with flexible architecture based on ISO MPEG-4 standard currently under specification and planned to be finalized in 1998. These codes are an experimental implementations for examining the feasibility of real-time and/or flexible S/W-based video codecs operating in intra and/or internetworking environments.