• 제목/요약/키워드: Locally adaptive scheme

검색결과 19건 처리시간 0.019초

Indicator Elimination for Locally Adaptive Scheme Using Data Hiding Technique

  • Chang, Hon-Hang;Chou, Yung-Chen;Shih, Timothy K.
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • 제8권12호
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    • pp.4624-4642
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    • 2014
  • Image compression is a popular research issue that focuses on the problems of reducing the size of multimedia files. Vector Quantization (VQ) is a well-known lossy compression method which can significantly reduce the size of a digital image while maintaining acceptable visual quality. A locally adaptive scheme (LAS) was proposed to improve the compression rate of VQ in 1997. However, a LAS needs extra indicators to indicate the sources, consequently the compression rate of LAS will be affected. In this paper, we propose a novel method to eliminate the LAS indicators and so improve the compression rate. The proposed method uses the concept of data hiding to conceal the indicators, thus further improving the compression rate of LAS. From experimental results, it is clearly demonstrated that the proposed method can actually eliminate the extra indicators while successfully improving the compression rate of the LAS.

구매자-판매자 워터마킹 프로토콜상에서 DCT 기반의 방향성 적응 워터마킹 (A Direction-Adaptive Watermarking Technique Based on 2DCT in the Buyer-Seller Watermarking Protocol)

  • 성택영;권기창;이석환;권기룡;우종호
    • 한국멀티미디어학회논문지
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    • 제17권7호
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    • pp.778-786
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    • 2014
  • Buyer-seller watermarking protocol is one of the copyright protection techniques which combine a cryptographic protocol used in electronic commerce with a digital wetermarking scheme aiming at proving the ownership of multimedia contents and preventing the illegal reproduction and redistribution of digital contents. In this paper, it is proposed a new watermarking scheme in an encrypted domain in an image that is based on the block-DCT framework. In order to implement watermarking scheme in a public-key cryptosystem, it is divided that frequency coefficients exist as real number into integer and decimal layer. And the decimal layer is modified integer type through integral-processing. Also, for robustness and invisibility required in watermarking scheme, it is designed a direction-adaptive watermarking scheme based on locally edge-properties of each block in an image through analyzing distribution property of the frequency coefficients in a block using JND threshold.

1기 무한모선 전력계통의 적응 전압 제어와 거버너를 이용한 주파수 진동의 억제 (Adaptive Voltage Control of a Single Machine Infinite Bus(SMIB) Power System with Governor Control for Reduced Oscillation of the Frequency)

  • 김석균;윤태웅
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2008년도 심포지엄 논문집 정보 및 제어부문
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    • pp.51-52
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    • 2008
  • In this paper, we propose two control schemes. The first control scheme is an adaptive passivity-based excitation control which regulates the terminal voltage to its reference. This controller is obtained through two steps: firstly, a simple direct adaptive passivation controller is designed for the power system with parametric uncertainties; then a linear PI controller is applied to converge the terminal voltage to its reference. The second control scheme is a linear governor control which consists of the frequency and the mechanical power. It is shown that the internal dynamics are locally stable with controllable damping. In the end, the boundness of all electrical variables, the frequency, the mechanical power, and the convergence of the terminal voltage to its reference can be achieved by these control schemes.

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영역 병합을 이용한 웨이블릿 잡음 제거 (Wavelet Denoising Using Region Merging)

  • 엄일규;김유신
    • 한국통신학회논문지
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    • 제30권3C호
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    • pp.119-124
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    • 2005
  • 본 논문에서는 영역 병합 방법을 사용하여 가변하는 국부 적응 창의 크기를 결정하는 새로운 알고리즘을 제안한다. 잡음 제거를 위한 한 점을 포함하고 있는 영역은 중복되지 않게 부분 영역으로 분할된다. 적절한 부분 영역을 선택하여 잡음 제거를 위한 국부 적응 창을 결정한다. 제안 방법에서는 거의 임의의 모양을 가지는 창을 얻을 수 있다. 모의실험결과에서 제안 방법이 다른 웨이블릿 기반 잡음 제거 방법보다 우수함을 보인다.

Adaptive mesh refinement/recovery strategy for FEA

  • Choi, Chang-Koon;Lee, Eun-Jin;Yu, Won-Jin
    • Structural Engineering and Mechanics
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    • 제17권3_4호
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    • pp.379-391
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    • 2004
  • This paper deals with the development of h-version adaptive mesh refinement and recovery strategy using variable-node elements and its application to various engineering field problems with 2D quadrilateral and 3D hexahedral models. The variable-node elements which have variable mid-side nodes on edges or faces are effectively used in overcoming some problems in connecting the different layer patterns of the transition zone between the refined and coarse mesh. A modified recovery technique of gradients adequate for variable-node elements and proper selection of error norms for each engineering field problems are proposed. In the region in which the error is greater than the permissible refinement error, the mesh is locally refined by subdivision. Reversely, in some parts of the domain having the error smaller than the permissible recovery error, the mesh is locally recovered (coarsened) by combination. Hierarchical structures (e.g. quadtrees and octrees) and element-based storage structures are composed to perform this adaptive process of refinement and recovery. Some numerical examples of a 3D heat conduction analysis of the concrete with hydration heat and a 2D flow analysis of vortex shedding show effectiveness and validity of the proposed scheme.

국소 분할된 패치를 갖는 비매개변수 금형묘사법을 이용한 3차원 박판성형공정 시뮬 레이션 (Finite Element Simulation of Sheet Metal Forming by Using Non-parametric Tool Description with Locally Refined Patches)

  • 윤정환;양동열;유동진
    • 소성∙가공
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    • 제5권1호
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    • pp.47-54
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    • 1996
  • An improved nonparametric tool description based on successive refined nonparametric patches is proposed and the related criterion for refinement is also discussed. In the proposed scheme any required order of tool surface conformity can be achieved by employing successive refinements according to the suggested criterion. By using the suggested adaptive tool refinement technique based on the nonparametric patch tool description the locally refined nonparametric tool surface with economic memory size and sufficient accuracy as well as with favorable characteristics for contact treatment can be obtained directly from the parametric patch related with commercial CAD system. Computation is carried out for a chosen complex sheet forming example of an actual autobody panel in order to verify the validity and the efficiency of the developed tool surface description.

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고정 부호화율의 국부적응 영상 변환부호화 (A Locally Adapative Fixed Rate DCT Image Coding)

  • 심영석;고재홍;이상학
    • 한국통신학회논문지
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    • 제14권1호
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    • pp.22-29
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    • 1989
  • 본 논문에서는 고정부호화율을 갖는 효과적인 적응 변환 부호화 방법을 제시, 연구한다. 본 방식에서는 각 블록마다 그 ac 에너지 크기에 비례하여 분산치 분포가 스케일을 달리하도록 정보원을 모델화 하고 그에 따라 비트배정을 하여 블록 양자화 한다. 본 방식은 적응 방식이면서 부호화율을 조정할 수 있는 장점이 있으며, 그 부호화율의 가변도 손쉽게 이루어진다. 제시된 방식의 성능은 컴퓨터 모의 실험을 통해 잘 알려진 Chen&Smith 방식과 신호대잡음비 및 사진 비교를 통해 평가된다.

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Adaptive Energy Optimization for Object Tracking in Wireless Sensor Network

  • Feng, Juan;Lian, Baowang;Zhao, Hongwei
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • 제9권4호
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    • pp.1359-1375
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    • 2015
  • Energy efficiency is critical for Wireless Sensor Networks (WSNs) since sensor nodes usually have very limited energy supply from battery. Sleep scheduling and nodes cooperation are two of the most efficient methods to achieve energy conservation in WSNs. In this paper, we propose an adaptive energy optimization approach for target tracking applications, called Energy-Efficient Node Coordination (EENC), which is based on the grid structure. EENC provides an unambiguous calculation and analysis for optimal the nodes cooperation theoretically. In EENC, the sleep schedule of sensor nodes is locally synchronized and globally unsynchronized. Locally in each grid, the sleep schedule of all nodes is synchronized by the grid head, while globally the sleep schedule of each grid is independent and is determined by the proposed scheme. For dynamic sleep scheduling in tracking state we propose a multi-level coordination algorithm to find an optimal nodes cooperation of the network to maximize the energy conservation while preserving the tracking performance. Experimental results show that EENC can achieve energy saving of at least 38.2% compared to state-of-the-art approaches.

Adaptive-and-Resolvable Fractional Repetition Codes Based on Hypergraph

  • Tiantian Wang;Jing Wang;Haipeng Wang;Jie Meng;Chunlei Yu;Shuxia Wang
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • 제17권4호
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    • pp.1182-1199
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    • 2023
  • Fractional repetition (FR) codes can achieve exact uncoded repair for multiple failed nodes, with lower computational complexity and bandwidth overhead, and effectively improve repair performance in distributed storage systems (DSS). The actual distributed storage system is dynamic, that is, the parameters such as node storage overhead and number of storage nodes will change randomly and dynamically. Considering that traditional FR codes cannot be flexibly applied to dynamic distributed storage systems, a new construction scheme of adaptive-and-resolvable FR codes based on hypergraph coloring is proposed in this paper. Specifically, the linear uniform regular hypergraph can be constructed based on the heuristic algorithm of hypergraph coloring proposed in this paper. Then edges and vertices in hypergraph correspond to nodes and coded packets of FR codes respectively, further, FR codes is constructed. According to hypergraph coloring, the FR codes can achieve rapid repair for multiple failed nodes. Further, FR codes based on hypergraph coloring can be generalized to heterogeneous distributed storage systems. Compared with Reed-Solomon (RS) codes, simple regenerating codes (SRC) and locally repairable codes (LRC), adaptive-and-resolvable FR codes have significant advantages over repair locality, repair bandwidth overhead, computational complexity and time overhead during repairing failed nodes.

Medical imaging을 위한 영상 보간 방법의 비교 (COMPARISON OF INTERPOLATION METHODS for MEDICAL IMAGING)

  • 이병길;하영호
    • 대한의용생체공학회:학술대회논문집
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    • 대한의용생체공학회 1990년도 추계학술대회
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    • pp.38-41
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    • 1990
  • A new spline function for resampling discrete signal adaptively is proposed. In general, B-spline function is used for an image interpolation because of its smoothness and continuity, but accompanies a large amount of blurring effect. Hence, we developed a new spline function to remedy this effect, with two procedures ; deblurring of Gaussian blurring and diminishing of aliasing effect caused by deblurring procedure. The proposed function has a parametric expression with $\alpha$ which is related to the variance of Gaussian blurring model. Locally adaptive resampling scheme is obtained by changing a according to statistical characteristics of an image. The proposed, interpolation function shows edge-sharpening effect as well as noise smoothing, with comparison to the conventional schemes.

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