• Title/Summary/Keyword: 헤드블록

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An Effective Video Block Placement Strategy on VOD Storage Server with MZR Disks (MZR 디스크를 채택한 VOD 저장서버의 효율적인 비디오 블록 배치방법)

  • Lim, Hyoung-Roung;Kim, Jeong-Won;Kim, Young-Ju;Chung, Ki-Dong
    • The Transactions of the Korea Information Processing Society
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    • v.4 no.12
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    • pp.2971-2984
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    • 1997
  • In this paper, we propose an efficient video block Placement scheme that utilize the current disk product that has MZR disk characteristic and users' skewed access pattern on VOD. Also, we evaluate its performance through simulation and modeling of VOD server. The basic placement rule is to place on MZR disks by LP, SHP methods according to the Zipf distribution of popularity. To verify the proposed scheme, we examined its performance on workstation with 2 MZR disks under varied skewed factors. The proposed placement scheme showed better response time than the random method. To extend proposed placement scheme to disk group, we analyzed the theoretical maximum numbers of concurrent users and the required buffer size per user. For performance parameters for the proposed scheme, we considered the disk head scheduling methods, the placement methods and the striping unit. The result of experiments showed that the proposed scheme was effective.

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An Effective Solution to Overcome the Restriction of SACK Blocks' Number in TCP SACK (오프셋을 활용한 효율적인 TCP SACK 메커니즘)

  • Lin, Cui;Hong, Choong-Seon
    • The KIPS Transactions:PartC
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    • v.12C no.7 s.103
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    • pp.1039-1046
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    • 2005
  • TCP SACK is the unique mechanism to reflect the situation of sink's sequence space, some TCP variants and proposals can perform in conjunction with SACK mechanism for achieving optimal performance. By definition of RFC 2018, however, each contiguous block of data queued at the data receiver is defined in the SACK option by two 32-bit unsigned integers in network byte order. Since TCP Options field has a 40-byte maximum length, when error bursts now, we note that the available option space may not be sufficient to report all blocks present in the receiver's queue and lead to unnecessarily force the TCP sender to retransmit Packets that have actually been received by TCP sink. For overcoming this restriction, in this thesis, a new solution named 'one-byte offset based SACK mechanism' is designed to further improve the performance or TCP SACK and prevent those unwanted retransmissions. The results or both theory analysis and simulation also show that his proposed scheme operates simply and more effectively than the other existing schemes by means of the least bytes and most robust mechanism to the high packet error rates often seen in networks environment.

DC Offset Adjusted Inter Prediction Algorithm for Improving H.264/AVC Video Coding Efficiency (H.264/AVC 동영상 압축율 향상을 위한 DC 오프셋 보정에 기반한 인터 예측 알고리즘)

  • Yoon, Dae-Il;Kim, Hae-Kwang
    • Journal of Broadcast Engineering
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    • v.16 no.5
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    • pp.793-796
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    • 2011
  • H.264/AVC compresses video data by applying DCT transform, quantization and entropy coding processes to the residual signal obtained by inter/intra prediction. This paper proposes a method enhancing an existing DC offset adjustment technology which uses information of neighboring blocks to reduce residual information for improving coding efficiency. DC offset information is not sent over bitstreams, but calculated in the same way both in the decoder and in the encoder. Experimental results show that the proposed method enhances coding efficiency by 0.25% in average BD-Rate compared to H.264/AVC and gives better or worse coding efficiency compared to the existing DC offset method depending on video sequences with coding efficiency degradation by 0.09% in average BD-Rate. This experimental results also show that further coding efficiency improvement is possible by applying the proposed method adaptively to slice or macroblock coding units.

Implementation of Viterbi Decoder on Massively Parallel GPU for DVB-T Receiver (DVB-T 수신기를 위한 대규모 병렬처리 GPU 기반의 비터비 복호기 구현)

  • Lee, KyuHyung;Lee, Ho-Kyoung;Heo, Seo Weon
    • Journal of the Institute of Electronics and Information Engineers
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    • v.50 no.9
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    • pp.3-11
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    • 2013
  • Recently, a plenty of researches have been conducted using the massively parallel processing of GPU for the implementation of communication system. In this paper, we tried to reduce software simulation time applying GPU with sliding block method to Viterbi decoder in DVB-T system which is one of European DTV standards. First of all, we implement DVB-T system by CPU and estimate cost time whereby the system processes one OFDM symbol. Secondly, we implement Viterbi decoder by software using NVIDIA's massive GPU processor. In our work, stream process method is applied to reduce the overhead for data transfer between CPU and GPU, as well as coalescing method to lower the global memory access time. In addition, data structure design method is used to maximize the shared memory usage. Consequently, our proposed method is approximately 11 times faster in 2K mode and 60 times faster in 8K mode for the process in Viterbi decoder.

Block Histogram Compression Method for Selectivity Estimation in High-dimensions (고차원에서 선택율 추정을 위한 블록 히스토그램 압축방법)

  • Lee, Ju-Hong;Jeon, Seok-Ju;Park, Seon
    • The KIPS Transactions:PartD
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    • v.10D no.6
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    • pp.927-934
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    • 2003
  • Database query optimates the selectivety of a query to find the most efficient access plan. Multi-dimensional selectivity estimation technique is required for a query with multiple attributes because the attributes are not independent each other. Histogram is practically used in most commercial database products because it approximates data distributions with small overhead and small error rates. However, histogram is inadequate for a query with multiple attributes because it incurs high storage overhead and high error rates. In this paper, we propose a novel method for multi-dimentional selectivity estimation. Compressed information from a large number of small-sized histogram buckets is maintained using the discrete cosine transform. This enables low error rates and low storage overheads even in high dimensions. Extensive experimental results show adventages of the proposed approach.

Thread Block Scheduling for GPGPU based on Fine-Grained Resource Utilization (상세 자원 이용률에 기반한 병렬 가속기용 스레드 블록 스케줄링)

  • Bahn, Hyokyung;Cho, Kyungwoon
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.22 no.5
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    • pp.49-54
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    • 2022
  • With the recent widespread adoption of general-purpose GPUs (GPGPUs) in cloud systems, maximizing the resource utilization through multitasking in GPGPU has become an important issue. In this article, we show that resource allocation based on the workload classification of computing-bound and memory-bound is not sufficient with respect to resource utilization, and present a new thread block scheduling policy for GPGPU that makes use of fine-grained resource utilizations of each workload. Unlike previous approaches, the proposed policy reduces scheduling overhead by separating profiling and scheduling, and maximizes resource utilizations by co-locating workloads with different bottleneck resources. Through simulations under various virtual machine scenarios, we show that the proposed policy improves the GPGPU throughput by 130.6% on average and up to 161.4%.

Encapsulation of IP Traffic through GFP in OTN Transmission Network (OTN 광전송망에서 GFP를 통한 IP 트래픽의 인캡슐레이션)

  • Lee, Chang-Ki;Yang, Choong-Reol
    • The KIPS Transactions:PartC
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    • v.15C no.6
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    • pp.567-572
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    • 2008
  • It is necessary to study about the scheme to accept IP traffic effectively in OTN, according to expect that IP traffic data will be increase constantly. In this paper, we studied the encapsulation method of IP traffic through GFP in OTN transmission network. Therefore we knew the IP/GFP/OTN method is more efficient than existing methods from structure, overhead rates and possibility of grow, and showed the functional block of high level about this method. Also we showed the implementation scheme of this method by processing the functional simulation to make use of VHDL programming.

A Study on the Surface Treatment of Magnesium for marine engine systems (초경량성 박용기관을 위한 마그네슘 표면처리)

  • Yun, Yong-Sup
    • Journal of Advanced Marine Engineering and Technology
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    • v.35 no.2
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    • pp.252-257
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    • 2011
  • Magnesium thin films for marine engine parts such as the engine block and the cylinder head cover etc. were prepared on the magnesium alloy(AZ91D) substrate by Thermo-electron activated Ion-plating method. The influence of gas pressure and substrate bias voltages on the crystal orientation and morphology of the films was investigated with X-ray diffraction and field emission scanning electron microscope(FE-SEM), respectively. Moreover, the effect of crystal orientation and morphology of the magnesium films on the its hardness property was investigated as well. From the results, the hardness of the films was increased in Ar gas pressure due to the grain boundary strengthening and occlusion effects.

Media Access Control Mechanism for Efficient Wireless Communication in Underwater Environments (수중 환경에서 효율적인 무선 통신을 위한 매체접근제어 메커니즘)

  • Jeong, Yoo-Jin;Shin, Soo-Young;Park, Soo-Hyun
    • Journal of the Korea Society for Simulation
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    • v.15 no.4
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    • pp.79-86
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    • 2006
  • Data transmission in poor environment like underwater has considerably serious delay rate and ewer rate. Like this environment usually has heavy fluctuation of error rate and limited wireless communication state. Therefore, mechanism using in such environment has to be efficient and simple. This paper suggests a new block ack mechanism, called the Pervasive Block ACK (PBA), which transmits aggregated ACKs. This mechanism takes effect on reducing number of traffic, decreasing overhead and delay rate in poor environment networks like underwater. Additionally, we can expect energy consumption. We verify propriety and efficiency of PBA through describing numerical result based analytical formula in this paper.

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The Effect of the Node Size on the Performance of B+trees on Flash Memory (플래시 메모리 상에서 B+트리 노드 크기 증가에 따른 성능 평가)

  • Choi, Hae-Gi;Park, Dong-Joo;Kang, Won-Seok;Lee, Dong-Ha
    • Proceedings of the Korea Information Processing Society Conference
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    • 2006.11a
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    • pp.333-336
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    • 2006
  • 플래시 메모리는 휴대폰과 PDA 와 같은 이동 기기에서 저장 장치로 널리 사용되고 있다. 또한 기가바이트(GB) 단위의 대용량화로 인해 노트북과 개인용 컴퓨터에서 보조기억장치로 사용되고 있다. 요즘에는 대용량의 데이터를 효율적으로 다루기 위한 B+트리와 같은 자료구조를 플래시 메모리상에서 저비용의로 구현하려는 연구들이 이루어지고 있다. 지금까지의 연구에서는 플래시 메모리에서 B+트리를 구축할 때 노드 크기를 플래시 메모리의 섹터(sector) 크기로 사용해왔다. 본 논문에서는 노드 크기가 플래시 메모리의 섹터 크기보다 더 커졌을 경우, 플래시 메모리에서 구현되는 B+트리의 구축성능과 검색성능 그리고 저장 공간 사용량을 비교 분석한다. 키 삽입 시 정렬 알고리즘과 비정렬 알고리즘을 각각 사용해 구축비용을 측정하였으며 효율적인 노드 검색을 위해 인덱스 노드 헤드 구조를 사용한다. 그리고 이러한 실험결과는 B+트리 노드 크기를 섹터 크기보다 블록 크기로 할당할 때 B+트리 성능의 우수성을 보인다.

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