• Title/Summary/Keyword: 블록처리 시간

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Combined discrete event and discrete time simulation framework for the improvement of shipbuilding process planning (조선 공정 계획의 수립 완성도 향상을 위한 이산 사건 및 이산 시간 혼합형 시뮬레이션 프레임워크)

  • Cha, Ju-Hwan;Roh, Myung-Il;Bang, Kyung-Woon;Lee, Kyu-Yeul
    • Journal of the Korea Society for Simulation
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    • v.17 no.4
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    • pp.71-80
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    • 2008
  • In this study, a simulation framework, which can support developing various simulation systems for the improvement of process planning in shipbuilding such as the block erection, the block turn-over, and so on, is proposed. In addition, a simulation kernel, which is a key component of the simulation framework, is implemented according to the concept of the combined discrete event and discrete time simulation. To evaluate the efficiency and applicability of the proposed simulation framework, it is applied to the block erection process in shipbuilding. The result shows that the proposed simulation framework can provide the consistent, integrated development environment for a simulation system, as compared with existing studies and commercial simulation systems.

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Relationships between Diversity Techniques and Channel Coding Rates for SC-FDMA Systems (SC-FDMA 시스템에서의 다이버시티 기술과 채널부호화율의 관계)

  • Rim, Min-Joong
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.34 no.1A
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    • pp.1-11
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    • 2009
  • In OFDMA or SC-FDMA systems one can generate time varying channels or frequency selective channels using multiple transmit antennas to achieve diversity without special space-time processing at the receivers. While low channel coding rate needs to be used for distributed-allocation SC-FDMA systems with a phase rolling technique to produce time fluctuation, relatively high channel coding rate can be used when cyclic delay diversity is used to increase frequency selectivity assuming quasi-static channel. On the other hand, for block-hopping SC-FDMA systems there is no significant difference between two diversity techniques in terms of optimal channel coding rates.

An Efficient Periodic-Request-Grouping Technique for Reduced Seek Time in Disk Array-based Video-on-Demand Server (디스크 배열-기반 주문형 비디오 서버에서의 탐색 시간 단축을 위한 효율적인 주기적 요청 묶음 기법)

  • Kim, Un-Seok;Kim, Ji-Hong;Min, Sang-Ryeol;No, Sam-Hyeok
    • Journal of KIISE:Computer Systems and Theory
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    • v.28 no.12
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    • pp.660-673
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    • 2001
  • In Video-on-Demand (VoD) servers, disk throughput is an important system design parameter because it is directly related to the number of user requests that can be served simultaneously. In this paper, we propose an efficient periodic request grouping scheme for disk array-based VoD servers that reduces the disk seek time, thus improving the disk throughput of VoD disk arrays. To reduce the disk seek time, the proposed scheme groups the periodic requests that access data blocks stored in adjacent regions into one, and arranges these groups in a pre-determined order (e.g., in left-symmetric or right-symmetric fashion). Our simulation result shows that the proposed scheme reduces the average disk bandwidth required by a single video stream and can serve more user requests than existing schemes. For a data block size of 192KB, the number of simultaneously served user requests is increased by 8% while the average waiting time for a user request is decreased by 20%. We also propose an adaptation technique that conforms the proposed scheme to the user preference changes for video streams.

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A Bitmap Index for Chunk-Based MOLAP Cubes (청크 기반 MOLAP 큐브를 위한 비트맵 인덱스)

  • Lim, Yoon-Sun;Kim, Myung
    • Journal of KIISE:Databases
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    • v.30 no.3
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    • pp.225-236
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    • 2003
  • MOLAP systems store data in a multidimensional away called a 'cube' and access them using way indexes. When a cube is placed into disk, it can be Partitioned into a set of chunks of the same side length. Such a cube storage scheme is called the chunk-based MOLAP cube storage scheme. It gives data clustering effect so that all the dimensions are guaranteed to get a fair chance in terms of the query processing speed. In order to achieve high space utilization, sparse chunks are further compressed. Due to data compression, the relative position of chunks cannot be obtained in constant time without using indexes. In this paper, we propose a bitmap index for chunk-based MOLAP cubes. The index can be constructed along with the corresponding cube generation. The relative position of chunks is retained in the index so that chunk retrieval can be done in constant time. We placed in an index block as many chunks as possible so that the number of index searches is minimized for OLAP operations such as range queries. We showed the proposed index is efficient by comparing it with multidimensional indexes such as UB-tree and grid file in terms of time and space.

A Study on the New Binary Block Matching Algorithm for Motion Estimation of Real time Video Coding (실시간 비디오 압축의 움직임 추정을 위한 새로운 이진 블록 정합 알고리즘에 관한 연구)

  • 이완범;김환용
    • Journal of the Institute of Convergence Signal Processing
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    • v.5 no.2
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    • pp.126-131
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    • 2004
  • Full search algorithm(FA) provides the best performance but this is usually impractical because of the large number of computations required for large search region. Fast search and conventional Boolean matching algorithms reduce computational complexity and data processing time but this algorithms have disadvantages that is difficult of implementation of hardware because of high control overhead and that is less performance than FA. This paper presents new Boolean matching algorithm, called BCBM(Bit Converted Boolean Matching). Proposed algorithm has performance closed to the FA by Boolean only block matching that may be very efficiently implemented in hardware for real time video communication. Simulation results show that the PSNR of the proposed algorithm is about 0.08㏈ loss than FA but is about 0.96∼2.02㏈ gain than fast search algorithm and conventional Boolean matching algorithm.

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Design of Low Power H.264 Decoder Using Adaptive Pipeline (적응적 파이프라인을 적용한 저전력 H.264 복호기 설계)

  • Lee, Chan-Ho
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.47 no.9
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    • pp.1-6
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    • 2010
  • H.264 video coding standard is widely used due to the high compression rate and quality. H.264 decoders usually have pipeline architecture by a macroblock or a $4{\times}4$ sub-block. The period of the pipeline is usually fixed to guarantee the operation in the worst case which results in many idle cycles and the requirement of high data bandwidth and high performance processing units. We propose adaptive pipeline architecture for H.264 decoders for efficient decoding and lower the requirement of the bandwidth for the memory bus. Parameters and coefficients are delivered using hand-shaking communication through dedicated interconnections and frame pixel data are transferred using AMBA AHB network. The processing time of each block is variable depending on the characteristics of images, and the processing units start to work whenever they are ready. An H.264 decoder is designed and implemented using the proposed architecture to verify the operation using an FPGA.

Distributed SFBC for Relay-Assisted Single Carrier Transmission over Uplink Fast Fading Channels (상향 링크 고속 페이딩 채널에서의 중계기 기반 단일 반송파 전송을 위한 분산 주파수 공간 블록 부호화 기법)

  • Seol, Dae-Young;Kwon, Ui-Kun;Im, Gi-Hong
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.44 no.5
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    • pp.25-32
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    • 2007
  • This paper proposes a distributed space-frequency block code (SFBC) for relay-assisted single carrier frequency-domain equalization (SC-FDE). The proposed technique achieves spatial diversity gain over fast fading channels without the complexity of multiple antennas. The mobile equipment of the proposed system has a very simple transmitter structure with constant amplitude transmit sequences, which is desirable especially for uplink communications. In order to obtain spatial diversity, the transmit sequence of relay is efficiently generated in the time domain, which is equivalent to the SFBC. Further, efficient implementation of relay and destination structures is also presented. Extensive simulation results show that the proposed system significantly outperforms the distributed space-time block code (D-STBC) SC-FDE over fast fading channels.

A Block-Based Volume Rendering Algorithm Using Shear-Warp factorization (쉬어-왑 분해를 이용한 블록 기반의 볼륨 렌더링 기법)

  • 권성민;김진국;박현욱;나종범
    • Journal of Biomedical Engineering Research
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    • v.21 no.4
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    • pp.433-439
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    • 2000
  • Volume rendering is a powerful tool for visualizing sampled scalar values from 3D data without modeling geometric primitives to the data. The volume rendering can describe the surface-detail of a complex object. Owing to this characteristic. volume rendering has been used to visualize medical data. The size of volume data is usually too big to handle in real time. Recently, various volume rendering algorithms have been proposed in order to reduce the rendering time. However, most of the proposed algorithms are not proper for fast rendering of large non-coded volume data. In this paper, we propose a block-based fast volume rendering algorithm using a shear-warp factorization for non-coded volume data. The algorithm performs volume rendering by using the organ segmentation data as well as block-based 3D volume data, and increases the rendering speed for large non-coded volume data. The proposed algorithm is evaluated by rendering 3D X-ray CT body images and MR head images.

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VQ Codebook Design and Feature Extraction of Image Information for Multimedia Information Searching (멀티미디어 정보검색에 적합한 영상정보의 벡터 양자화 코드북 설계 및 특징추출)

  • Seo, Seok-Bae;Kim, Dae-Jin;Kang, Dae-Seong
    • Journal of the Korean Institute of Telematics and Electronics S
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    • v.36S no.8
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    • pp.101-112
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    • 1999
  • In this paper, the codebook design method of VQ (vector quantization) is proposed an method to extract feature data of image for multimedia information searching. Conventional VQ codebook design methods are unsuitable to extract the feature data of images because they have too much computation time, memory for vector decoding and blocking effects like DCT (discrete cosine transform). The proposed design method is consists of the feature extraction by WT (wavelet transform) and the data group divide method by PCA (principal component analysis). WT is introduced to remove the blocking effect of an image with high compressing ratio. Computer simulations show that the proposed method has the better performance in processing speed than the VQ design method using SOM (self-organizing map).

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Adaptive Hierarchical Hexagon Search Using Spatio-temporal Motion Activity (시공간 움직임 활동도를 이용한 적응형 계층 육각 탐색)

  • Kwak, No-Yoon
    • Journal of Digital Contents Society
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    • v.8 no.4
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    • pp.441-449
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    • 2007
  • In video coding, motion estimation is a process to estimate the pixel of the current frame from the reference frame, which affects directly the predictive quality and the encoding time. This paper is related to AHHS(Adaptive Hierarchical Hexagon Search) using spatio-temporal motion activity for fast motion estimation. The proposed method defines the spatio-temporal motion activity of the current macroblock using the motion vectors of its spatio-temporally adjacent macroblocks, and then conventional AHS(Adaptive Hexagon Search) is performed if the spatio-temporal motion activity is lower, otherwise, hierarchical hexagon search is performed on a multi-layered hierarchical space constructed by multiple sub-images with low frequency in wavelet transform. In the paper, based on computer simulation results for multiple video sequences with different motion characteristics, the performance of the proposed method was analysed and assessed in terms of the predictive quality and the computational time. Experimental results indicate that the proposed method is both suitable for (quasi-) stationary and large motion searches. The proposed method could keep the merit of the adaptive hexagon search capable of fast estimating motion vectors and also adaptively reduce the local minima occurred in the video sequences with higher spatio-temporal motion activity.

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