• 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.

• The KIPS Transactions:PartB
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• v.8B no.5
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• pp.523-532
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• 2001

A Critical issue in the performance of a video-on-demand system is the required I/O bandwidth of the Video server in order to satisfy clients requests, and it is the crucial resource that may cause delay increasingly. Several approaches such as batching and piggybacking are used to reduce the I/O demand on the video server through sharing. Bathing approach is to make single I/O request for storage server by grouping the requests for the same object. Piggybacking is th policy for altering display rates of requests in progress for the same object to merge their corresponding I/O streams into a single stream, and serve it as a group of merged requests. In this paper, we propose a reservation-based hybrid disk bandwidth reduction policy that dynamically reserves the I/O stream capacity of a video server for popular videos according to the loads of video server in order to schedule the requests for popular videos immediately. The performance of the proposed policy is evaluated through simulations, and is compared with that of bathing and piggybacking. As a result, we know that the reservation-based hybrid disk bandwidth reduction policy provides better probability of service, average waithing time and percentage of saving in frames than batching and piggybacking policy.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.12C
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• pp.1251-1264
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• 2002

Currently, audio streaming services such as on-demand service and live service support only a limited number of clients. They also suffer from a lack of stability and degradation of service quality due to their inefficient use of network resources. Futhermore, since the streaming services usually do not consider dynamic services, they are very inconvenience to use. In order to resolve these drawbacks, we propose a novel audio streaming system based on MPEG-2 AAC file format which are facilitated with the network bandwidths efficiently. The proposed system supports QoS for audio streaming as well as guarantees a stability while streaming service is undergoing. Moreover, the system provides a dynamic interface which enables us to use the streaming service more easily and to manage streaming servers with convenient manner. On the contrary, most of the current available static interface streaming services are mainly depending only on a single fixed web page between client and server, which in consequence lead us to use unflexible static service environment. Our implementation results show the proposed system improves the performance compared to those of the currently existing systems that use MP3 file format. It also provides some benefits such as a stability of service and a easy to management of streaming servers.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.2
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• pp.327-335
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• 2001

In the 21st century, broadcasting, communication, and computer have been integrated due to the development of digital technology. Accordingly, to overcome the limit of respective communication media and to maintain them, their independent area shall not be classified. This study is to examine the future environment of digital TV broadcasting, to analyze customizing type service and interactive type TV technology, and to make asymmetric interactive digital TV publication broadcasting system, which is TV broadcasting in the next generation to treat visual image, sound, and various data all together by harmonizing broadcasting and communication like ISDB(Integrate Service Digital Broadcasting). In addition, to develop service on publication broadcasting with high quality, this study is to propose to develop relative devices for TV/PC reception to realize a new communication type TV publication broadcasting, by analyzing technology for producing, sending, transmitting, receiving, and saving to apply to customizing type interactive system and by examining its application.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.7
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• pp.1621-1630
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• 2009

There is a lot of recent research to provide services of dynamic distributed contents in P2P-based distributed environment. Distributed services of contents objects, however, have problems in QoS and dynamic management of segments. This paper proposed a new segment management method for the service of P2P-based distributed contents. The proposed method manages groups by the SGM(Segment Group Manager). The SGM manages streaming efficiently by the grouping of segments to be served in P2P environment. The segments in the same group cooperate for improved QoS using the management structure based on the distance and relationship. The distance-based management structure is for the improvement of retrieval efficiency while the relationship-based management structure is for the improvement of service ratio. The simulation results of the proposed method showed improvements in average transmission efficiency and average service rate. The improvement is 8% - 30% in average transmission efficiency and 10% - 30% in average service rate.

• Proceedings of the IEEK Conference
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• 2003.07c
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• pp.2653-2656
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• 2003

본 논문에서는 IP-Based 디지털 TV Settop box에서 발생할 수 있는 신뢰성의 문제점에 대해서 설명하고, 이를 향상, 보완할 수 있는 방법을 제안한다. IP-Based DTV Settop box 는 사용자에게 인터넷 검색이나 주문형 비디오와 같은 고부가가치의 서비스를 제공하기 위하여 범용 운영체제를 주로 사용한다. 하지만, 범용 운영체제의 사용에 따른 시스템의 불안정성과 운영체제 자체의 오류가 발생하였을 때는 Settop box의 기본기능 조차 사용하지 못하게 될 수도 있다. 본 논문에서는 이러한 문제를 해결하기 위하여 중앙 제어부를 모니터링하는 별도의 제어부를 따로 두어 중앙 제어부가 오 동작 하였는지 검사하도록 한다. 만약, 중앙 제어부가 비정상적인 상태이면 별도의 제어부가 Settop box의 기본 기능을 계속할 수 있도록 유도하고, 시스템이 재 부팅되어 정상동작을 하면 제어 권을 다시 중앙 제어부로 넘겨준다. 또한, 중앙 제어부의 시스템이 부팅하는 동안 제안된 구조를 이용해 Settop box의 기본 기능인 디지털 TV시청을 가능하도록 하는 방안에 대해서도 논한다.

• Electronics and Telecommunications Trends
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• v.29 no.4
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• pp.59-71
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• 2014

클라우드 컴퓨팅은 확장 가능한 물리적/가상 공유 자원에 주문형(on-demand) 형태로 네트워크 접근을 가능케하는 컴퓨팅 패러다임을 의미하며, 사용자가 애플리케이션, 플랫폼, 자원을 네트워크를 통해 공급자로부터 지원받는 IT 서비스 형태로 진화해 왔다. 이에 따라, 클라우드 컴퓨팅기술의 발전과 함께 관련 시장이 급속도로 성장하고 있으며, 관련 표준화도 국내외적으로 이슈화되고 있다. 본고에서는 ITU-T와 ISO/IEC JTC 1을 중심으로 한 국제 공적 표준기구와 여러 사실화 표준기구의 최근 클라우드 컴퓨팅 표준화 동향을 조사한다. 또한, 국제 표준화에 대응하는 국내 표준화 활동현황도 요약하여 분석한다.

• Journal of Korea Multimedia Society
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• v.4 no.3
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• pp.205-214
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• 2001

As the real time multimedia data service has become available due to the rapid progress of computer and Internet technology, the users can enjoy the newly developed service, which is called Video On-Dem-and(VOD). However, most of service providers have not paid their attention much on the software for various service modes on VOD, but they are only concentrating un the hardware to provide with the high resolution video display. Therefore, the service providers are recently to pay more attention on the software to cope with the various demands of users than hardware. So this paper has designed and implemented the VOD service system for those demands. Since the VOD service system suggested by this paper enable off-line search functions through E-mail, the users can possibly get the necessary information from off-line Search without connecting to the server while the current VOD service can prominently help users to save the time and effort to sea고 and select the Video contents by using periodical current awareness service supported by PUSH technology and user oriented information booking and feedback service supported by SDI service.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.6
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• pp.1377-1384
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• 1997

We propose a new scheme to provide the fast forward and reverse(FF/R) functions to users in Video On Demand Service System. The proposed scheme is to use only I and P pictures obtained by sampling MPEG2 bit-steam. New frame raes for FF/R play are specified with parameters of MPEG2 syntrx. Bits of I and P pictures are reduced in three steps: Variable length decoding(VLD), Inverse quantization and Requantization. The proposed scheme is ecnomical in the sense that it can provide FF/R function without any additional requirement on the bandwidth and on the storage media in video server.

• Proceedings of the Korea Contents Association Conference
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• 2003.05a
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• pp.88-91
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• 2003

웹기반 교육은 사용자가 원하는 시간과 장소에서 학습자 스스로 수준별 학습이 .가능하며 능동적으로 학습에 참여할 수 있는 장점이 있다. 이를 바탕으로 한 웹 코스웨어는 원거리 학습자들의 학습 욕구를 가능케 했으며 기존의 텍스트, 사운드를 통한 단순한 콘텐츠에서 동영상 이미지를 중심으로 한 멀티미디어 동영상 강의, 하이퍼텍스트로 구성된 인터넷 홈페이지 등 주문형 교육 서비스(EOD : Education On Demand)가 가능해 졌다. 이처럼 현재 많은 분야에서 다양한 방법으로 웹기반 교육콘텐츠를 개발하여 학습에 활용하고 있다. 이에 본 연구에서는 양적으로 팽창하는 웹 코스웨어의 효율성을 분석하고 이를 통하여 보다 질적인 우수성을 포함하는 콘텐츠 활용 방안을 연구하고자 한다.