• Journal of KIISE:Computer Systems and Theory
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• v.29 no.1
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• pp.22-34
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• 2002

In this paper, we consider ring embeding problem in faulty (n,k) star graphs which is recently proposed as an alternative interconnection network topology, By effectively utilizing such strategies as series of dimension expansions and even distribution of faulty nodes into sub-stars in graph itself. we prove that it is possible to construct a maximal fault-free ring excluding only faulty nodes when the number of faults is no more than n-3 and $n-k{\geq}2$, and also propose an algorithm which can embed the corresponding ring in (n.k)-star graphs This results will be applied into the multicasting applications that the underlying cycle properties on the multi-computer system.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.8
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• pp.623-628
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• 2000

Video-on-demand system in which users can request any video through the network at any time is made possible by rapid increase in network bandwidth and capacity of the media server. However true video-on-demand system cannot support all requests since bandwidth requirement is still too demanding. Therefore efficient bandwidth reduction algorithm is necessary. both the piggybacking method and the batching method are novel solutions that can provide more logical number of streams than the physical system can support. Of course each of them has its pros and cons. hence piggybacking with batching-by-size can take advantage of both the schemes. Some parameters such as the size of batch and the size of the catch-up window should be adjusted and order to maximize the bandwidth reduction for piggybacking with batching-by-size method. One of the most important parameters is decided optimally in this paper. Simulation shows that the optimized parameter can achieve considerable reductionand consequently remarkable enhancement in performance.

• Journal of the Korea Computer Industry Society
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• v.5 no.9
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• pp.911-920
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• 2004

Intensive studies have been made in the area of VOD server. Multimedia files in the VOD sever are characterized with the large volume of data, the requirements of synchronization and real-time playback of streams. The basic goal of the study is to find an efficient mechanism to allow maximum number of users under the limited resources such as Bu11er size and disk bandwidth. we propose a efficient user-grouping policy for multi-casting services with dynamic monitoring and management of VOD sever resources. Simulation results show that the rate of buffer usage and QOS change of proposed scheme are about 23% performance improved than that of traditional methods. This implies that our method can allow much more users for given resources.

• Journal of Internet Computing and Services
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• v.6 no.5
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• pp.1-9
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• 2005

In a role based access control through attribute certificate, the use of role assignment certificates and role specification certificates can reduce management cost and the overhead incurred by changing roles, Highly distributed computing environments such as ubiquitous computing environments not having global or broad control. need another attribute certificate management technique, Actually just having role specification certificate separately reduce management cost, But for better performance we structure role specification, We group roles and make the role group relation tree, It results secure and efficient role renewing and distribution, For scalable role specification certificate distribution, the multicasting of packets is used, We take into account the packet lass and quantify performance enhancements of structuring role specification certificates.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.126-129
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• 2015

Device-to-device (D2D) communications, a subset of Proximity-based Services that enables direct communication between LTE network subscribers, is gaining popularity. It is well underway to be adopted in cellular communication systems for pedestrian and connected-vehicles alike. In this paper, we briefly present our model of an Evolved Packet Core Network-assisted device discovery simulator and show the applicability of Proximity-based Services for Vehicular Ad-hoc Networks. Through the performance evaluation based on the developed simulation environment, it is shown that in case when users gather in the same vicinity, as in public transportation, LTE network data can be efficiently offloaded and multicasted through Wi-Fi for e.g. delivering traffic-related information and for the benefit of infotainment service consumers.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.8
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• pp.1172-1179
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• 2010

In this paper, we analyze and design requirements of Network Function block and System Function block of MiTS network protocol based on Light-Weight Ethernet, also implement and test the protocol and library files. Light-Weight Ethernet Protocol consists of Network Function block and System Function block. NF receives and sends datagram based on UDP multi-casting communication. SF processes messages after distinguished Sentence and Binary Image Data.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.11b
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• pp.651-654
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• 2003

IPv6는 최신 장치에 대한 추가기능요구와 사용한 수 있는 인터넷 주소의 고갈이 임박해옴에 따라 만들어졌다. 기존의 IPv4 환경에서는 주소 부족에 대한 단기 해결책으로 NAT 등 여러 가지 메커니즘이 제시되었다. IPv6의 등장으로 IPv4의 주소 부족이라는 문제를 해결하였으나 NAT는 계속해서 사용되고 있으며 이로 인해 보안 서비스측면, 인터넷 및 통신 아키텍처 투명성 등의 문제들이 제기되고 있다. NAT 관련 문제를 해결하기 위한 기존의 접근 방법은 NAT와 상호운용성을 전제로 하고 있으나, 본 논문은 NAT를 대체할 수 있는 IPv6의 기능을 기술한다. NAT가 없어지면 각종 보안 서비스에 있어서 문제가 되고 있는 많은 복잡한 문제들도 해결된다. IPv6는 NAT를 대체를 위해 주소 공간, 자동설정메커니즘, 멀티캐스팅 범주(scope), 흡별 처리의 기능들이 존재한다. 각 기능들은 NAT의 장점을 대체할 수 있다.

• Journal of Internet Computing and Services
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• v.7 no.5
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• pp.71-79
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• 2006

The GNUnet proposed a file encoding method by lKB block size to support anonymity of files and decentralizes encoded block to peers through unstructured model. but, the encoding and block decentralizing method with 600$\sim$700MB large multimedia file appeared two problems. First problem. it need addition R block and I block, which make about 4% of storage resource. Second problem, unstructured model added network load by broadcasting decentralizing method. This paper suggest variable encoding block size and structured model by block decentralizing solution. Suggested encoding method reduced block request supplementary block generation to 1% and network load by proposal structured model sending answer through dedicated peer to decentralize block.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2002.11a
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• pp.243-246
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• 2002

It is expected that intelligent broadcasting service (IBS) will be able to provide broadcast programs based on user preference and program-associated information (metadata) in order to assist users to easily navigate the program contents being broadcast. So users can access program contents anytime/anywhere in the way they want. In this paper we propose a framework for IBS based on an intelligent software agent platform so called FIPA (Foundation for Intelligent Physical Agents). We use an FIPA implementation. so called FIPA-OS, as a platform for exchanging user preferences and program information as FIPA messages between a server and clients. The user preference is modeled as the User Preference description scheme in MPEG-7 MDS (Multimedia Description Scheme).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.3B
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• pp.431-439
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• 2010

The security systems using signatures cannot protect servers from new types of Internet worms. To protect servers from Internet worms, this paper proposes a system removing malicious processes and executable files without using signatures. The proposed system consists of control servers which offer the same services as those on protected servers, and agents which are installed on the protected servers. When a control server detects multicasting attacks of Internet worm, it sends information about the attacks to an agent. The agent kills malicious processes and removes executable files with this information. Because the proposed system do not use signatures, it can respond to new types of Internet worms effectively. When the proposed system is integrated with legacy security systems, the security of the protected server will be further enhanced.