• Journal of Institute of Control, Robotics and Systems
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• v.5 no.8
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• pp.898-906
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• 1999

A control structure is introduced for the purpose of rejecting periodic (or repetitive) disturbances on a tracking system. The objective of the proposed structure is to drive the output of the system to the reference input that will result in perfect following without any changing the inner configuration of the system. The structure includes an adaptation block which learns the dynamics of the periodic disturbance and forces the interferences, caused by disturbances, on the output of the system to be reduced. Since the control structure acquires the dynamics of the disturbance by on-line adaptation, it is possible to generate control signals that reject any slowly varying time-periodic disturbance provided that its amplitude is bounded. The artificial neural network is adopted as the adaptation block. The adaptation is done at an on-line process. For this , the real-time recurrent learning (RTRL) algoritnm is applied to the training of the artificial neural network.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.10 no.2
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• pp.46-52
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• 2011

This paper presents adaptive spread-spectrum watermarking scheme on the H.264/AVC video. The H.264/AVC has become popular video coding since it's compression performance has been improved greatly. That is why there is not enough space for embedding watermark using the spread-spectrum method. To overcome this problem, we propose selective block embedding scheme. The blocks which don't contain non-zero DCT (Discrete Cosine Transform) coefficients are selected by value. So we have enough space to embed watermarks. Experimental result shows that proposed scheme improves recovery rates of watermark about 12% and reduces distortion of watermarked video.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.9B
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• pp.1292-1298
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• 2001

본 논문에서는 공간 영역에서의 블록 분류 (block classification)와 순방향 신경망 필터(feedforward neural network filter)를 이용한 블록 기반 부호화에서의 적응적 블록화 현상 제거 알고리듬을 제안하였다. 제안한 방법에서는 각 블록 경계를 인접 블록간의 통계적 특성을 이용하여 평탄 영역과 에지 영역으로 분류한 후, 각 영역에 대하여 블록화 현상이 발생하였다고 분류된 클래스에 대하여 적응적인 블록간 필터링을 수행한다. 즉, 평탄 영역으로 분류된 영역 중 블록화 현상이 발생한 영역은 오류 역전파 학습 알고리듬 (error backpropagation learning algorithm)에 의하여 학습된 2계층 (2-layer) 신경망 필터를 이용하여 블록화 현상을 제거하고, 복잡한 영역으로 분류된 영역 중 블록화 현상이 발생한 영역은 에지 성분을 보존하기 위하여 선형 내삽을 이용하여 블록간 인접 화소의 밝기 값만을 조정함으로써 블록화 현상을 제거한다. 모의 실험 결과를 통하여 제안한 방법이 객관적 화질 및 주관적 화질 측면에서 기존의 방법보다 그 성능이 우수함을 확인하였다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.11a
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• pp.42-45
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• 2011

최근ISO/IEC와 ITU는 공동 협력팀(Joint Collaborative Team on Video Coding-JCT-VC)을 구성하여 HEVC(High Efficiency Video Coding)라 불리는 새로운 비디오 압축 표준 기술을 개발하고 있다. JCT-VC의 목표 중 하나는 H.264/AVC 압축률의 2배를 향상하는 것으로 최근 HEVC 테스트 모델(HEVC Test Model - HM)을 확정했다. HM의 여러 기술 중에서 확장 블록 구조 (large block structure) 기술은 CU(Coding Unit)와 TU(Transform Unit), PU(Partition Unit)로 구성된다. CU와 TU는 압축 단위와 변환 기술을 확장한 반복적인 문법구조(recursive syntax structure)이며, PU는 H.264/AVC과 동일한 형태를 띈다. 확장 블록 구조는 CU, PU, TU의 여러 조합에 의해 다양한 모드를 지원하여 압축 성능은 높아졌지만 HM 부호화기의 복잡도는 증가한다. 본 논문에서는 HM에 채택된 확장 블록 구조 기술에 대해 설명한 후, 계층적 B프레임 구조로 부호화 되는 경우 이전 레벨의 CU Depth 정보를 이용하여 현재 레벨의 CU Depth를 효과적으로 제한하여 기존의 방법보다 빠르게 부호화하는 방법을 제안한다.

• Proceedings of the IEEK Conference
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• 2002.06d
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• pp.101-104
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• 2002

This paper proposes a unique data embedding algorithm for the video sequence. It describes two processings: shot boundary detection and robust data embedding. First, for the shot boundary detection, instead of using absolute frame differences, block by block based relative frame differences are employed. Frame adaptive thresholding values are also employed for the better detection. Second, for the robust data embedding, we generate message template and then convolve and correlate it with carrier signal. And then we embed data on the time domain video sequence. By using these two methods, watermarks into randomly selected frames of shots. Watermarks are detected well even if several certain shots are damaged because we embed watermark into each shot equally.

• Proceedings of the IEEK Conference
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• 2000.07a
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• pp.421-424
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• 2000

In this paper, we propose a window warping method to solve stereo matching problems in projective distortion region. Because the projective distortion region cant t be estimated with fixed-size block matching algorithm, we use the window warping technique in block matching process. The position of a reference window to resample is obtained adaptively according to the degree of reliability in disparity estimated previously. The initial disparity and reliability are obtained by applying a well known hierarchical strategy. The experimental result shows that considerable improvement is obtained in the projective distortion region.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.357-358
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• 2006

We propose the robust PBFLMS in noises, which is the enhanced acoustic echo canceller using ACPBF-LMS(Alternative Constrained Partitioned Block Frequency domain Least Mean Square) algorithm. The defect of the block structure filtering is the deterioration of convergence efficiency from noise and interference. To improve the performance of convergence efficiency, noise effect should be reduced. The new method of reducing noise effect is proposed, which apply the estimated background noise to adaptive filter step size. By experiments, the proposed acoustic echo canceller has TCL of 50dB, and always provides faster convergence speed and lower complexity than the full-tap NLMS. We also carried out an implementation of PBFLMS using ARM9EJ-S.

• Proceedings of the IEEK Conference
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• 2000.07a
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• pp.46-49
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• 2000

An iterative deblocking algorithm for DCT-compressed images using two-dimensional FIR filters adapted for local directionality of each block, is proposed. First, we introduce a set of simple lowpass filters, which are adapted for edges of different angles. In conventional deblocking methods based on lowpass-filtering and convex projections, a single filter is applied to a whole image. In the proposed method, on the other hand, a suitable filter is chosen out of the directional filters designed previously in every subimage (typically $8{\times}8$ block). Experimental results indicate that adaptive filtering improves PSNR at each iteration.

• ETRI Journal
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• v.33 no.2
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• pp.295-298
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• 2011

We propose a motion-compensated frame interpolation method in which an accurate backward/forward motion vector pair (MVP) is estimated based on a parabolic motion model. A reliability measure for an MVP is also proposed to select the most reliable MVP for each interpolated block. The possibility of deformation of bidirectional corresponding blocks is estimated from the selected MVP. Then, each interpolated block is produced by combining corresponding blocks with the weights based on the possibility of deformation. Experimental results show that the proposed method improves PSNR performance by up to 2.8 dB as compared to conventional methods and achieves higher visual quality without annoying blockiness artifacts.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2013.11a
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• pp.6-7
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• 2013

본 논문은 기존의 고정블록 알고리즘에서 발생할 수 있는 객체 추적의 문제점을 보안한 다중 블록을 이용한 적응적 블록 정합 알고리즘을 제안한다. 기존의 고정블록을 이용한 정합 알고리즘은 추적 대상 객체의 크기와 블록의 크기가 추적 성능에 미치는 영향이 크기 때문에 객체 추적에 실패하는 경우가 발생한다. 본 논문에서는 고정된 블록 정합 알고리즘의 문제점을 해결하기 위해 다중 블록을 이용하여 객체 내의 포함된 블록들을 효과적으로 선택하고 선택된 블록들의 특성으로부터 효과적인 가중치를 부여하여 추적 성능을 향상시킨다. 제안된 알고리즘은 블록 정합 알고리즘 중 가장 정확도가 높다고 알려진 전역 탐색 방법을 이용하여 정확도를 평가 하였다.