• Journal of Satellite, Information and Communications
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• v.9 no.4
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• pp.38-41
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• 2014

Due to the diversity of device performances and the possibility of providing multimedia service through many networks, media consumption environment has been changed in various ways. In recent, mobile services and broadcasting services started to provided through IP network. According to this flow changes, there was great demand for various multimedia services through heterogenous networks. To solve this problem, MMT was suggested as a standard of multimedia transport which replaces MPEG-2 TS(Transport Stream) which is used for HD(High Definition) transport. MMT can be provided various broadcasting based on IP through terrestrial, satellite, cable broadcasting networks, and also deliver multimedia through many networks at the same time. MMT was risen as a method of servicing UHD broadcasting. In this paper, we present an implementation of service architecture for hierarchical UHD broadcasting over heterogenous networks using MMT.

• Journal of Korea Multimedia Society
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• v.16 no.8
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• pp.954-961
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• 2013

To enhance the efficiency of network, content-centric networking (CCN), one of future Internet architectures, allows network nodes to temporally cache transmitted contents and then to directly respond to request messages which are relevant to previously cached contents. Also, since CCN uses a hierarchical content-name, not a host identity like source/destination IP address, for request/response packet routing and CCN request message does not include requester's information for privacy protection, contents-providers/ network nodes can not identify practical requesters sending request messages. So to send back relevant contents, network nodes in CCN records both a request message and its incoming interfaces on Pending Interest Table (PIT). Then the devices refer PIT to return back a response message. If PIT is exhausted, the device can not normally handle request/response messages anymore. Hence, it is needed to detect/react attack to exhaust PIT. Hence, in this paper, we propose improved detection/reaction schemes against attacks to exhaust PIT. In practice, for fine-grained control, this proposal is applied to each incoming interface. Also, we propose the message framework to control attack traffic and evaluate the performance of our proposal.

• The Journal of the Korea Contents Association
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• v.16 no.4
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• pp.224-230
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• 2016

Recently, CCN(Content Centric Network) has been extensively interested in the literature to transfer data traffic efficiently according to the rapid growth of multimedia services on the Internet. CCN is a new networking paradigm to deliver contents efficiently based on the named content not the named or addressed host. This paper presents a mathematical approach for analyzing CCN-caching systems with two routers. Considering the stochastic characteristics of communication networks, the caching system is modeled as a two dimensional Markov chain. This paper analyzes the structural feature of the transition rate matrix in the Markov chain and presents a numerical solution for the CCN-caching performance of the two router system. In addition, various numerical examples are presented.

• Proceedings of the Korea Contents Association Conference
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• 2007.11a
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• pp.270-273
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• 2007

The overlay multicast that has been recently presented as an alternative for the IP multicast has been getting much persuasion by the advancement of the network techniques to enforce routing in application-level. But, The overlay multicast is a problem of delay and the load of the traffic control. In this paper, we suggested to an effective transmission routing tree between users based on overlay multicast of Internet broadcasting Service. And we evaluated an optimal value of transmission delay about Internet broadcasting using this suggest model.

• Proceedings of the Korea Contents Association Conference
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• 2007.11a
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• pp.60-64
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• 2007

Increasing using multimedia services as VoIP, Video conference, DMB, IPTV, etc, it is necessary to increase network traffics and develop the mechanism about a flow control for real time traffic transmission. In order to transfer realtime multimedia data, the transfer rate can be control on network state data measuring packet losses of a receiver and delay time of packets through getting periodical feedback RTP/RTCP packet. This paper describes using efficiant flow control on multicast that can reduce errors according to getting feedback tranfer delay and proposes the mechanism that can adapt dynamic change of network. In simulation, the transfer rate can efficiently be control on dynamic change of network and it makes the maximum of the use of a bandwidth and the minimum of packet losses.

• Journal of Korea Multimedia Society
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• v.16 no.12
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• pp.1403-1412
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• 2013

In the maritime ships or airplanes, users should utilize the satellite channel in orer to use web service. However, the satellite channel is costly and does not give users satisfied response time. In the ship, the users may receive plenty of extra data when they obtain internet news. The extra data may be unnecessary image and advertise. Therefore, they should pay unnecessary data usage charges as well. In this paper, we suggest a proxy model that solves the problem of cost and speed. The proposed proxy reduces the of data through the satellite link by image and advertising blocking, caching, image re-requesting functions. It's performance was tested by a real satellite communication.

• Digital Contents
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• no.10 s.125
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• pp.84-85
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• 2003

기업과 기업간, 사람과 사람사이에 의견을 주고 받기 위한 매체가 다양화되고 있다. 방문이나 우편 등에 의한 의사 교환에서 전화, 이메일을 거쳐 메신저가 등장해 실시간으로 의견을 주고 파일 전송을 하고 있다. 메신저는 1:1문자 대화에서 1:다수의 형태로 진화되더니 급기야는 서로의 얼굴을 보고, 음성을 들으며 웹사이트, 문서 등을 공유하면서 회의를 진행할 수 있게 됐다.

• Proceedings of the Korea Database Society Conference
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• 2001.11a
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• pp.536-554
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• 2001

인터넷 이용자의 증가와 멀티미디어 등 대용량 콘텐츠에 대한 수요의 증가로 인해 데이터 트래픽은 기하 급수적으로 늘어나는 데 비해 네트웍 성능향상에 대한 투자는 이에 미치지 못함으로서 결과적으로 인터넷은 트래픽의 병목현상, 즉 정체현상이 발생하게 되었으며 점차 그 정도가 심해지고 있다. 이 문제를 해결하기 위해 제안하는 방안이 바로 전략적 CDN(Content Delivery Network) 이다. 현실적으로, 본 연구는 물리적인 망 증설만으로는 트래픽 체증 문제를 해결하기는 어려우므로 주요 ISP 네트웍에 전략적 캐시서버를 설치하여 CP의 콘텐츠를 각 ISP 네트웍마다 분산하여 저장하고 이용자의 요청 시 이용자의 인터넷 회선이 물려 있는 ISP 네트웍에서 바로 콘텐츠를 전송하여 데이터 손실과 속도 저하 등의 문제를 해결하는 CDN의 구성과 그 효과를 실증적으로 밝혔다.

• The Journal of the Korea Contents Association
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• v.8 no.2
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• pp.67-73
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• 2008

Recently, due to the rapid advances of mobile communication, multimedia service can be provided by mobile devices. Cellular network tends to uses SIP as a call setup protocol in order to provide various multimedia service to consumers. Cellular network holds the characteristic of higher BER(Bit Error Rate), narrower bandwidth than the wired network. The value of SIP RTI(Retransmission Time interval) based on the wired network decreases a network efficiency and increases a call setup delay over cellular network. By using NS-2 simulator, we show new SIP RTI value adequate over cellular network. We design and implement home network by using the modified SIP that is suitable for cellular network.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.538-541
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• 2006

Recently researches of P2P media streaming have been actively published, but the research what kind of P2P overlay networks are better to delivering media data has not been attended. This paper designs a P2P streaming media system model. In this system, we constructs a Half-Structure P2P overlay protocol based on node's capability as the infrastructure of streaming application, which utilizes the heterogeneity of the nodes to maintain topology, presents a active contents diffusing algorithm and Two-stage search algorithm, make it possible for nodes in P2P system to collect information according their capacity and reduces the number of forwarding packet compared with flooding. Also, we give an optimal scheme to scheduling media data.