Seung-Won Lee

Pusan National University, Tsau-liang-hai, Busan, South Korea

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Publications (10)0 Total impact

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    ABSTRACT: Servicing mobile hosts over the Internet has some problems including nodes’ location, independent addressing, address conversion and packet forwarding as well as mobile host’s location management. However, packet transmission and independent addressing in the mobile environments are very similar to the ones in the multicasting environment. So, in this paper, we propose a new scheme about how to manage the multicasting group and to set the communication path in the mobile environment by applying two-level addressing mode, which is similar to mobile IP, for lcation-independent address setting. More specifically, we propose the smooth handoff scheme that minimizes the handoff delay. To check the performance of our proposed scheme, we modified the NS-2 network simulator and as a result, we showed that our proposed scheme is better than other techniques in terms of transmitted packets’ throughput.
    Embedded and Ubiquitous Computing, International Conference EUC 2004, Aizu-Wakamatsu City, Japan, August 25-27, 2004, Proceedings; 01/2004
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    ABSTRACT: In this paper we analyzed the workloads based on the access logs from three media servers which have different characteristics. These servers deliver highly qualified contents such as movies, dramas, education contents and music videos throughout Korea on the web. We analyzed the workloads in terms of media file size, user access pattern and distribution of the user request arrival time. Then we applied these specific characteristics of analysis to the design of replacement algorithm for proxy caching scheme. The proposed proxy caching scheme shows 3 ~ 10 % improvement of BHR and reduces the server workload by decreasing replacement amount.
    Advances in Multimedia Information Processing - PCM 2004, 5th Pacific Rim Conference on Multimedia, Tokyo, Japan, November 30 - December 3, 2004, Proceedings, Part I; 01/2004
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    ABSTRACT: In this paper, we propose a space replacement algorithm called LSU for the efficient proxy cache management and analyze its performance. For this, we first analyze the log files of one of the major broadcasting system’s media server to see what client’s characteristics are when they access video objects. As result of this analysis, we generate the probability density function based on each request’s system resource usage. We do simulations to check the performance of our proposed algorithm comparing it with LRU and LFU. As result of the simulations, we show that in most cases, LSU works better than LFU and LRU regardless of the size of the replacement time window.
    Information Networking, Networking Technologies for Enhanced Internet Services International Conference, ICOIN 2003, Cheju Island, Korea, February 12-14, 2003, Revised Selected Papers; 01/2003
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    ABSTRACT: Multicast delivery is one of solutions to reduce the cost in large VOD systems. However, it is difficult to implement the interactive operations for an individual user in multicast transmission system. In this paper, we propose the Alternative Multicast Transmission Scheme (AMTS) to serve a large number of users and reduce the initial delay while supporting VCR operations. For hot video users, this scheme uses the Frame-Based Multicast Transmission (FBMT) to support both nor- mal playback and VCR playback via the identical channels. The proposed FBMT is to deliver frames via an appropriate channel based on frame type (I, P, B) of MPEG video. The AMTS has better performance than other multicast systems in terms of both initial blocking probabilities and VCR blocking probability.
    Information Networking, Wireless Communications Technologies and Network Applications, International Conference, ICOIN 2002, Cheju Island, Korea, January 30 - February 1, 2002, Revised Papers, Part II; 01/2002
  • Si-Yong Park, Seung-Won Lee, Ki-Dong Chung
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    ABSTRACT: The rapid growth of the mobile environment has been resulted in servicing not only voice data but also multimedia data. Specially, mobility is a significant feature in mobile environment. In this paper, we propose a multimedia transmission architecture to exploit the mobility in the mobile multimedia network. This architecture can provide seamless communication by overlapping regions among foreign networks in a mobile multimedia network. We propose a bandwidth negotiation policy which a foreign network can admit more requests of new mobile hosts. And the policy can control fairly the differences of allocated bandwidth of foreign networks.
    Advances in Multimedia Information Processing - PCM 2002, Third IEEE Pacific Rim Conference on Multimedia, Hsinchu, Taiwan, December 16-18, 2002, Proceedings; 01/2002
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    ABSTRACT: In a VoD (video-on-demand system), admission control that is used to serve multimedia data efficiently has to be performed by an accurate grasp of the condition of surplus resources. Most of all, we need an adaptable admission control mechanism because the disk has an irregular response time caused by external elements of the disk, and also by the high deviation in demand. In this measurement-based statistical admission control scheme, as we suggested in this research, we can get both a maximum resource utilization and QoS guarantee through the off-line process and the on-line process. From performance evaluations, we show that the video server can provide maximum resource utilization with QoS guarantee through the precision of the performance by measurement and adaptable admission control according to the requested bandwidth
    Information Networking, 2001. Proceedings. 15th International Conference on; 02/2001
  • Jung-Min Choi, Seung-Won Lee, Ki-Dong Chung
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    ABSTRACT: Multicast transmission is one of the solutions to reduce the cost in large VOD systems. However, it is difficult to implement the interactive operations for an individual user in a multicast transmission system. We propose a frame based multicast transmission scheme to serve a large number of users and reduce additional channels while supporting VCR operations. This scheme supports both normal playback and VCR playback via the identical channels. The proposed FBMT is to deliver frames via appropriate channels based on frame type (I, P, B) of MPEG video. FBMT has superior performance over the multicast systems in terms of both initial blocking probabilities and VCR blocking probability. The initial blocking probability of the FBMT is decreased as the arrival rate is increased further, VCR blocking probability is always 0% to admitted users
    Parallel and Distributed Systems, 2001. ICPADS 2001. Proceedings. Eighth International Conference on; 02/2001
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    ABSTRACT: In this paper, we describe a highly available distributed video on demand (VoD) system, which is inherently fault tolerant. Multiple servers provide the VoD service. We propose techniques that detect and recover faults like those disk faults, server faults and system faults. And we present the server switching method that preserves reliability and real-time. When a server fails, it is replaced by another server in a transparent way; the clients are unware of change. The switching between the faulty server and the new server is smooth. The server switching method is alternate depending on the spare load rates of the surviving servers. Also we present the flow control mechanism so that the client keeps the proper buffer occupancy during such server-switching period. With fault tolerant capability, our VoD system can maintain a continuous service to client despite of faults.
    Proceedings of the 2001 IEEE International Conference on Multimedia and Expo, ICME 2001, August 22-25, 2001, Tokyo, Japan; 01/2001
  • Jung-Min Choi, Seung-Won Lee, Ki-Dong Chung
    Proceedings of the 2001 IEEE International Conference on Multimedia and Expo, ICME 2001, August 22-25, 2001, Tokyo, Japan; 01/2001
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    ABSTRACT: The MPEG data used in a video server has variable bit rate (VBR) characteristics because each frame is different in size, and the difference of movements between frames is also variable. So, a video server must consider this VBR characteristic in resource management. So far, for VBR data, many scheduling schemes have been proposed. When VBR video is displayed, if disk bandwidth is allocated assuming the worst case, the utilization of disk bandwidth becomes very low. In order to raise the utilization of disk bandwidth, a prefetching scheme is used, but this needs extra buffers. We propose a WVS (Window-based VBR data scheduling scheme) for VBR data. WVS prefetches data with a limited maximum bandwidth for each window unit. Moreover, WVS, which considers the state of system resources, can obtain a tradeoff between disk bandwidth and buffer allocation. The proposed scheme constructs in advance CTL (Constant Time Length) meta data about a video and dynamically allocates resources for each window unit. In simulations, we compared the proposed scheme with previous schemes in terms of the size of resource allocation and the number of concurrent users
    Multimedia Computing and Systems, 1999. IEEE International Conference on; 08/1999