• Proceedings of the Korea Multimedia Society Conference
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• 2001.11a
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• pp.12-17
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• 2001

본 논문에서는 낮은 대역폭의 무선 네트워크상에서 MPEG 스트리밍을 위한 방법으로, DCT 계수의 제거에 기반한 QoS 필터링 방법과 매크로 블록상의 움직임 벡터와 인트라 블록의 비율을 고려한 영상분식을 통하여 분석된 내용에 가장 알맞는 필터의 선택과 필터의 적용 수준을 네트워크의 상태에 따라 결정하여 대역폭을 만족시킬 수 있는 비트레이트의 조절로서 원활한 스트리밍을 가능하게 하며 영상분석을 통하여 영상의 품질을 높여 고품질의 영상 멀티미디어 서비스와 최소한의 부하를 줄 수 있는 설계로서 서버운용시 과효율을 놀일 수 있도록 한다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2018.11a
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• pp.15-17
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• 2018

VVC(Versatile Video Coding)는 입력된 영상을 CTU(Coding Tree Unit) 단위로 분할하여 코딩하며, 이를 다시 QTBTT(Quadtree plus binary tree and triple tree)로 분할하고, TU(Transform Unit)도 이와 같은 단위로 분할된다. 따라서 TU의 크기는 $4{\times}4$, $4{\times}8$, $4{\times}16$, $4{\times}32$, $8{\times}4$, $16{\times}4$, $32{\times}4$, $8{\times}8$, $8{\times}16$, $8{\times}32$, $16{\times}8$, $32{\times}8$, $16{\times}16$, $16{\times}32$, $32{\times}16$, $32{\times}32$, $64{\times}64$의 17가지 종류가 있다. 기존의 VVC 참조 Software인 VTM에서는 디블록킹필터와 SAO(Sample Adaptive Offset)로 이루어진 인루프필터를 이용하여 에러를 복원하는데, 본 논문은 TU 크기에 따라서 원본블록과 복원블록의 차이(에러)가 통계적으로 다름을 이용하여 서로 다른 CNN(Convolution Neural Network)을 구축하고 에러를 복원하는 방법으로 VTM의 인루프 필터를 대체한다. 복원영상의 에러를 감소시키기 위하여 TU 블록크기에 따라 DenseNet의 Dense Block기반 CNN을 구성하고, Hyper Parameter와 복잡도의 감소를 위해 네트워크 간에 일부 가중치를 공유하는 모양의 Network를 구성하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.1C
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• pp.65-73
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• 2006

The purpose of this study is to design and analyze the pre-modulation filter with the variable -3dB cutoff frequency and linear phase response for bandlimiting the allocation of radio frequency bandwidth in PCM/FM transmission system. For the implementation of this required filter, the digital FIR filter, DAC and variable 2nd order LPF have been constructed with the filter block which designed and analyzed by each stage in order to satisfy the attenuation characteristic requirement of the analog 7th order bessel filter. The paper also concerned the linear phase properties for the filter block. Especially we have carried out the linear phase simulation with real parts for variable 2nd order LPF and compared this simulation results with the one of the fixed bandwidth 2nd order bessel filter for validating the linear phase requirement.

• Journal of Broadcast Engineering
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• v.15 no.4
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• pp.513-526
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• 2010

In this paper, we propose a de-blocking filter for improvement of coding efficiency and computational complexity reduction on a high definition video coding. Recently, the H.264/AVC standard-based research for high definition video coding method is under way because the amount of used of high definition videos is on the increase. The H.264/AVC de-blocking filter is designed for low bitrate video coding and it improves not only the subjective quality but also coding efficiency by minimizing the blocking artifact. However, the H.264/AVC de-blocking filter that strong filtering is performed is not suitable in a high definition video coding which occurs relatively low blocking artifact. Also, the conventional de-blocking filter has high computational complexity in decoder side. The computational complexity of the proposed method is reduced about maximum 8.8% than conventional method. Furthermore, the coding efficiency of the proposed method is about maximum 7.3% better than H.264/AVC de-blocking filter.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.44 no.6
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• pp.30-35
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• 2007

H.264/AVC provides better quality than other algorithms by using a deblocking filter to remove blocking distortion on block boundary of the decoded picture. However, this filtering process includes lots of memory accesses, which cause delay of overall decoding time. In this paper, we propose a data-reuse algorithm to speed up the process for the deblocking filter. To reuse the data, a new filtering order is suggested. By using this order, we reduce the memory access and accelerate the deblocking filter. The modeling of proposed algorithm is compiled under ARM ADS1.2 and simulated with Armulator. The results of the experiment compared with H.264/AVC standard are achieved on average 58.45% and 57.93% performance improvements at execution cycles and memory access cycles, respectively.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.45 no.3
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• pp.142-148
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• 2008

Though a deblocking filter of H.264/AVC provides enhanced image quality by removing blocking artifact on block boundary, the complex filtering operation on this process is a dominant factor of the whole decoding time. In this paper, we designed an ASIP to accelerate deblocking filter operation with the proposed instruction set. We designed a processor based on a MIPS structure with LISA, simulated a deblocking later model, and compared the execution time on the proposed instruction set. In addition, we generated HDL model of the processor through CoWare's Processor Designer and synthesized with TSMC 0.25um CMOS cell library by Synopsys Design Compiler. As the result of the synthesis, the area and delay time increased 7.5% and 3.2%, respectively. However, due to the proposed instruction set, total execution performance is improved by 18.18% on average.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.12
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• pp.46-54
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• 1998

In this paper we propose a fast adaptive image restoration filter using DCT-based block classification for reducing block artifacts in compressed images. In order to efficiently reduce block artifacts, edge direction of each block is classified by using the DCT coefficients, and the constrained least square (CLS) on the observation that the quantization operation in a series of coding process is a nonlinear and many-to-one mapping operator. And then we propose an approximated version of constrained optimization technique as a restoration process for removing the nonlinear and space-varying degradation operator. For real-time implementation, the proposed restoration filter can be realized in the form of a truncated FIR filter, which is suitable for postprocessing reconstructed images in HDTV, DVD, or video conference systems.

• Proceedings of the Korea Information Processing Society Conference
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• 2019.05a
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• pp.194-196
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• 2019

컨소시엄 블록체인은 허가된 멤버로 구성된 여러그룹이 하나의 원장을 공유한다. 이때 하위멤버의 트랜잭션 및 멤버 인증은 블록생성에 참여하는 신뢰된 노드로부터 유효성을 검증받는다. 따라서 컨소시엄 블록체인의 그룹 간 멤버의 트랜잭션 공유는 Privacy문제를 야기한다. 본 논문에서 컨소시엄 블록체인에서의 privacy를 위해 익명신용장기반의 익명프로토콜을 제안한다. 본 제안 방식은 다중블룸필터를 이용하여 긍정오류율을 높이고 효율적으로 검색하도록 한다. 또한 Blind Signature를 통해 컨소시엄 멤버간 메시지에 대한 익명성을 보존하면서 인증에 대한 서명은 유지하도록 한다. 결과적으로 컨소시엄 멤버 간 Privacy를 보존하면서 인증 트랜잭션을 블룸필터의 다중패턴으로 검증하여 컨소시엄 블록체인에서의 익명프로토콜(Anonymous protocol)을 제안한다. 이로써 컨소시엄 블록체인에서의 신뢰기반의 서버 시스템의 확장과 privacy 향상을 제공한다.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.967-970
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• 2001

본 논문에서는 적응 필터의 계수 갱신에서 가변 블록을 사용하는 방법을 제안하였다. 데이터 블록의 길이는 MSE 학습곡선의 시정수에 비례하도록 하였다. 이 방법에서는 적응 필터가 정상상태로 접근함에 따라 스텝사이즈를 조정하여 필터계수 갱신의 횟수를 줄일 수 있다. 제안한 방법의 유용성을 입증하기 위한 컴퓨터모의 실험을 통해 기존의 최적 스텝사이즈 수열을 이용한 알고리듬과 가변 스텝사이즈 알고리듬과 성능을 비교하였다. 그리고 MSE 의 초기값을 최소화하는 최적 초기 스텝사이즈를 유도하였다. 유도된 최적 스텝사이즈를 가변 스텝사이즈 알고리듬에 적용, 그 성능을 평가 하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.10 no.6
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• pp.308-316
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• 1985

A new implementation of Block Adaptive filter in frequency domain is presented in this paper. Block digital filtering involves the calculation of a block or finite set of filter out put from a block of input values. A fast convergence algorithm of block adaptive filter is developed using Gordar theory and compared with the performance results of Satio algorithm and BLMS algorithm. Form the result we can be shown that the convergence state of given algorithm is not only faster than BLMS algorithm but also the resulting convergence error is less than the convergence error of Satio algorithm.