• Journal of KIISE:Information Networking
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• v.32 no.1
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• pp.80-88
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• 2005

In ubiquitous spaces, a user wants to be provided with a VOD service while moving one space to another freely. Since the traditional VOD system is dependent on user location, the VOD server transmits video data to a single client during a session. If the user moves to another space, he/she should close the old session and make a new request for the same video. However, the location-aware VOD system supports user mobility by closing and opening the session automatically. That is, the VOD system automatically perceives the movement of a user and allows the server to change the data flow so that a client near the user can receive the video data. This paper proposes a location-aware VOD service architecture and a session handoff scheme to provide a mobile user with continuous video delivery and implements a location-aware VOD prototype system based on Jini and Java. In experiment, we show that the proposed handoff scheme has a smaller handoff delay than the other handoff scheme.

• Proceedings of the Korean Society of Computer Information Conference
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• 2013.07a
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• pp.65-68
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• 2013

스마트폰을 이용하여 인터넷 검색, SNS 및 VOD의 이용률이 증가함에 따라 스마트폰에서 제공하는 VOD 및 멀티미디어 서비스에 관심이 높아지고 있다. 특히 사용자의 위치를 기반으로 사용자에게서 유용한 정보를 추론하고 이에 맞은 비디오를 제공하는 위치기반 VOD 서비스에 대한 관심도 역시 상당히 높다. 그러나 사용자들이 도로 또는 거리가 아닌 지하철, 쇼핑몰 등의 건물 내부에 있을 때에는 GPS를 사용할 수 없기 때문에 기존의 위치기반 VOD 시스템은 작동을 하지 못한다. 본 논문은 스마트폰 센서를 이용하여 사용자의 걸음 수와 진행 방향을 판정하고, 이를 바탕으로 사용자의 위치를 판정함으로 옥내위치기반 VOD 서비스가 가능한 스마트폰용 앱을 설계하고 구현한다.

• Journal of Digital Contents Society
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• v.15 no.2
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• pp.251-261
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• 2014

In the typical P2P VOD system, it is very important to develop the fast and efficient peer searching scheme since the peers frequently join and leave to/from P2P system. This paper proposes a new peer searching scheme for P2P VOD system based on DHT network environment. The proposed scheme constructs DHT network by managing the peers having close playback starting times and close network locations into a peer all together. The peer information is mapped onto DHT nodes by hashing the key values each of which consists of the starting time and network location of the peer. From the simulation results, the number of messages required to search the partner peers are decreased, and the number of buffer maps exchanging among the peers are also decreased. The proposed scheme can reduce the average network distances among the partner peers. As a result, the proposed scheme makes routing more efficient and it saves the network resources by decreasing communication traffic overhead.

• Journal of the Korean Institute of Intelligent Systems
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• v.14 no.6
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• pp.674-677
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• 2004

This paper deals with a systematic approach for the construction of the fixed-delay tree search (FDTS) detector in the intersymbol interference channel. The approach is based on the efficient multi-dimensional space partitioning. The Voronoi diagram (VoD) and the Delaunay tessellation (DT) of the multi-dimensional space are applied to implement the algorithm. In the proposed approach, utilizing the geometric information contained in the VOD/DT, the relative location of the observation sequence is determined which has been shown to reduce the implementation complexity. Detailed construction procedures are discussed followed by an example from the intersymbol interference communication channel.