• 전자공학회논문지B
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• 제31B권2호
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• pp.45-55
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• 1994

In this paper, a block based image approximation technique using the Self Affine System(SAS) from the fractal theory is suggested. Each block of an image is divided into 4 tiles and 4 affine mapping coefficients are found for each tile. To find the affine mapping cefficients that minimize the error between the affine transformed image block and the reconstructed image block, the matrix euation is solved by setting each partial differential coefficients to aero. And to ensure the convergence of coding block. 4 uniformly partitioned affine transformation is applied. Variable block size technique is employed in order to applynatural image reconstruction property of fractal image coding. Large blocks are used for encoding smooth backgrounds to yield high compression efficiency and texture and edge blocks are divided into smaller blocks to preserve the block detail. Affine mapping coefficinets are found for each block having 16$\times$16, 8$\times$8 or 4$\times$4 size. Each block is classified as shade, texture or edge. Average gray level is transmitted for shade bolcks, and coefficients are found for texture and edge blocks. Coefficients are quantized and only 16 bytes per block are transmitted. Using the proposed algorithm, the computational load increases linearly in proportion to image size. PSNR of 31.58dB is obtained as the result using 512$\times$512, 8 bits per pixel Lena image.

• 대한조선학회논문집
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• 제43권1호
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• pp.103-118
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• 2006

At the initial design stage, the generation process of the production material information of a building block and the simulation process of the block erection, which are required to perform the production planning and scheduling, have been manually performed using 2D drawings, based on the data of parent ships, and subjective intuition from past experience. To make these processes automatic, the accurate generation method of the production material information and the convenient simulation method of the block erection based on the initial hull structural model(3D CAD model), were developed in this study. Here, the initial hull' structural model was generated from the initial hull structural CAD system early developed by us. To evaluate the developed methods. these methods were applied to corresponding processes of a deadweight 300,OOOton VLCC. As a result. it was shown that the production material information of a building block can be accurately generated and the block erection can be conveniently simulated in the initial design stage.

• 대한임베디드공학회논문지
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• 제15권2호
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• pp.43-49
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• 2020

In this paper, we propose a stage-wise knowledge transfer method that uses block-wise retraining to transfer the useful knowledge of a pre-trained residual network (ResNet) in a teacher-student framework (TSF). First, multiple hint information transfer and block-wise supervised retraining of the information was alternatively performed between teacher and student ResNet models. Next, Softened output information-based knowledge transfer was additionally considered in the TSF. The results experimentally showed that the proposed method using multiple hint-based bottom-up knowledge transfer coupled with incremental block-wise retraining provided the improved student ResNet with higher accuracy than existing KD and hint-based knowledge transfer methods considered in this study.

• 한국컴퓨터정보학회논문지
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• 제16권6호
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• pp.71-77
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• 2011

본 논문에서는 번호판 인식 시스템에서 번호판 영상의 화질 개선을 위하여 국부 블록(Local block : LB) 학습기반의 초해상도 알고리즘을 제안한다. 본 논문에서 국부 블록은 영상 내에서 정보를 담고 있는 최소 단위로 정의하였으며, 학습의 기본 단위가 된다. 제안된 방법은 먼저 다양한 환경에 적합한 훈련 국부 블록 set을 생성하였다. 훈련 국부 블록 set은 고해상도 국부 블록과 저해상도 국부 블록의 순서쌍으로 구성되며 다양한 크기의 번호판과 열화 영상에 대응하기 위하여 다양한 크기와 열화를 갖는 저해상도 국부 블록 훈련 set을 구성하였다. 그 다음으로는 저해상도 입력 영상에서 복원해야할 정보를 훈련 국부 블록 set에서 추출/융합하는 과정을 제안하였다. 모의 실험결과, 열화된 저해상도 번호판 영상에 대해 제안한 방법이 효과적인 복원 성능을 나타내는 것을 확인할 수 있었다.

• The Korean Journal of Pain
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• 제34권3호
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• pp.271-287
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• 2021

Background: Postoperative pain management is crucial for patients undergoing total knee arthroplasty (TKA). There have been many recent clinical trials on post-TKA peripheral nerve block; however, they have reported inconsistent findings. In this meta-analysis, we aimed to comprehensively analyze studies on post-TKA analgesia to provide evidence-based clinical suggestions. Methods: We performed a computer-based query of PubMed, Embase, the Cochrane Library, and the Web of Science to retrieve related articles using neurothe following search terms: nerve block, nerve blockade, chemodenervation, chemical neurolysis, peridural block, epidural anesthesia, extradural anesthesia, total knee arthroplasty, total knee replacement, partial knee replacement, and others. After quality evaluation and data extraction, we analyzed the complications, visual analogue scale (VAS) score, patient satisfaction, perioperative opioid dosage, and rehabilitation indices. Evidence was rated using the Grading of Recommendations Assessment, Development, and Evaluation approach. Results: We included 16 randomized controlled trials involving 981 patients (511 receiving peripheral nerve block and 470 receiving epidural block) in the final analysis. Compared with an epidural block, a peripheral nerve block significantly reduced complications. There were no significant between-group differences in the postoperative VAS score, patient satisfaction, perioperative opioid dosage, and rehabilitation indices. Conclusions: Our findings demonstrate that the peripheral nerve block is superior to the epidural block in reducing complications without compromising the analgesic effect and patient satisfaction. Therefore, a peripheral nerve block is a safe and effective postoperative analgesic method with encouraging clinical prospects.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 심포지엄 논문집 정보 및 제어부문
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• pp.167-169
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• 2005

The occurrence of a single bit error in transmission bitstream leads to serious temporal and spatial errors. Because moving picture coding as MPEG-2 based on block coding algorithm uses variable length coding and motion compensation coding algorithm. In this paper, we propose algorithm to conceal occurred error of I-frames in transmission channel using data of the neighboring blocks in decoder. We divide a damaged macroblock of I-frame into four sub blocks and compose new macroblock using the neighboring blocks for each sub block. We estimate the block with minimum difference value through block matching with previous frame for new macroblocks and replace each estimated block with damaged sub block in the same position. Through simulation results, the proposed algorithm will be applied to a characteristic of moving with effect and shows better performance than conventional error concealment algorithms from visual and PSNR of view.

• 한국컴퓨터정보학회논문지
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• 제7권4호
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• pp.102-107
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• 2002

블록 코딩을 기반으로 하는 영상의 압축 부호화는 영상 및 비디오 압축 표준으로 적용되어 왔다. 그런데 영상 복원 시 발생하는 블록효과에 대한 효율적인 측정방법을 찾아보기 힘든 실정이다. 본 논문에서는 서브블록 DCT부호화를 이용한 복원 영상에 대한 객관적인 블록효과 측정방법을 제안한다. 제안한 방법이 주관적인 순위매김과 일치하는 블록효과 측정방법임을 실험결과로서 입증한다 또한 제안한 이 새로운 측정방법은 복원 영상에서 쉽게 그리고 효율적으로 블록효과를 측정하는데 널리 사용될 수 있을 것으로 기대한다.

• 한국통신학회논문지
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• 제24권12B호
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• pp.2438-2446
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• 1999

대부분의 블록기반 스테레오 쌍 압축 기술들은 모든 스테레오 쌍에서 가장 일치하는 블록을 찾기 위해 일정한 블록크기와 탐색영역 크기를 사용한다. 그러나 각 스테레오 쌍마다 서로 다른 불일치를 가지기 때문에 모든 스테레오 쌍에 동일한 블록 크기와 탐색영역 크기를 적용하는 것은 효과적이지 못하다. 본 논문에서는 스테레오 쌍의 전체 불일치를 구하는 방법을 제시하고 구하여진 전체 불일치를 사용하여 블록기반 스테레오 쌍의 압축에 적용할 블록 크기와 탐색영역 크기를 결정한다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 추계종합학술대회 논문집
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• pp.1097-1100
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• 1999

Due to the significant computation of full search in motion estimation, extensive research in fast motion estimation algorithms has been carried out. However, most of the algorithms have the degradation in predicted images compared with the full search algorithm. To reduce an amount of significant computation while keeping the same prediction quality of the full search, we propose a fast block-matching algorithm based on gradient magnitude of reference block without any degradation of predicted image. By using Taylor series expansion, we show that the block matching errors between reference block and candidate block are proportional to the gradient magnitude of matching block. With the derived result, we propose fast full search algorithm with adaptively determined scan direction in the block matching. Experimentally, our proposed algorithm is very efficient in terms of computational speedup and has the smallest computation among all the conventional full search algorithms. Therefore, our algorithm is useful in VLSI implementation of video encoder requiring real-time application.

• 한국멀티미디어학회논문지
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• 제5권3호
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• pp.316-322
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• 2002

본 논문에서는 파일 데이터의 실시간 재생 서비스를 제공하기 위한 UNIX파일 시스템의 연속 블록 할당에 대하여 다루고 있다. 설계된 블록 할당 방식은 사용자가 저장 데이터와 함께 지정한 소비 전송율을 지원할 수 있도록 적절한 디스크 위치에 데이터를 배치하여 실시간 재생 서비스를 지원할 수 있도록 하고 있다. 이를 위하여 데이터 전송율에 영향을 미치는 요소 중에서 가변적인 특성인 연속 블록 수와 저장 데이터들의 실린더 간격과의 관계를 분석하여 특정 실린더 간격 별로 연속 블록을 저장하는 방식을 채택하였다. UNIX시스템의 블록 할당 방식은 임의의 실린더 위치에서 연속 블록을 찾는 것이 비효율적 이기 때문에 새로운 형태의 비트맵 방식의 유휴 블록 기법을 사용하였다. 비트맵 방식의 블록 관리 기법은 파일 시스템 블록들을 비트 단위로 사용/비사용 여부를 표시하여 임의의 실린더 위치에 존재하는 블록이 사용 가능한지를 효율적으로 검색할 수 있도록 하였다.