• Journal of information and communication convergence engineering
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• v.8 no.3
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• pp.295-300
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• 2010

Recent researches of network structure are moving to high-level networks because there are already many research results of low-level network. Especially, current network services has been changed to the multimedia service using multicast routing such as IPTV(Internet Protocol Television) service. And then previous multicast services were provider oriented. So previous multicast structures were organized server/client model. But future multicast services will make user oriented services. Therefore there will be many service providers in the future. At this point, we study P2P network for supporting multi provider. So we research load balancing and contents lookup protocols in P2P network. In this paper, we propose network protocol and system based on super peer P2P for load balancing and efficiently service search. And we considered mobile environment for mobile IPTV.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10d
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• pp.637-641
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• 2006

현재 인터넷 등의 네트워크와 개인 컴퓨터의 발전으로 인하여 피어(peer)들 간의 파일을 공유하는 시스템에 대한 필요가 증가하고 있다. 이 피어들 간에는 이질적 시스템과 환경을 가지고 있다. 이러한 피어들 간의 자료교환은 서로의 의미가 달라지며, 사용자가 원하는 자료를 쉽게 찾을 수 없다. 이 문제점의 해결을 위해 현재 웹에서 사용자가 원하는 자료에 보다 정확하게 응답을 하기 위해 사용되는 온톨로지 개념을 P2P 시스템에 적용하여 각 시스템 또는 사용자간의 시맨틱 갭(Semantic Gap)을 없애고, 이를 위한 파일 온톨로지를 본 논문은 제안한다. 본 논문에서는 RDF를 사용하여 파일 온톨로지 개념을 현재의 P2P 파일 공유 시스템 중 하나인 Tapestry[1]에 RDF를 적용하여 자료 검색 시 사용자가 원하는 자료를 보다 정확하게 응답할 수 있는 효율적인 파일 검색 시스템을 제안한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.3
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• pp.421-429
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• 2006

Recently, DHT-based Structured P2P System have a attention to scalability and providing efficient lookup by routing. Retrieving content of DHT-based P2P require knowledge of the exact identifier of sharing file. But user may wish to search for sharing file using descriptive keyword or content. To resolve the problem, this paper propose Extended-CAN mechanism to support keyword search. We defined content-based keyword and identifier of sharing file, and PLS extended to KID and CKD for keyword, common keyword processing. As a result, Extended-CAN mechanism provide efficient keyword search for DHT-based Structured P2P System.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.05a
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• pp.429-430
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• 2013

유비쿼터스 기술의 발전과 더불어 스마트 교육과 관련된 연구가 활발히 진행되고 있다. 교육 분야에서의 최신 IT 기술의 도입의 첫 단추는 도서관 시스템 이였다. 이용자와 도서관의 자료를 효율적으로 관리하기 위하여 많은 기관에서 RFID(Radio Frequency Identification) 소자를 기반으로 관련 RFID 리더 장비와 데이터 관리 장비를 구축하였다. 이러한 기술을 기반으로 유비쿼터스 기술을 학생들이 가장 많은 시간을 보내는 교실의 환경에 적용하여 스마트 교육 시스템으로 구축하는 것은 교육의 첨단화와 연계되어 연구되고 있다. 본 연구에서는 기존의 자원을 활용하여 네트워크 환경에서의 자원 배분을 원활히 이뤄내는 P2P 기술과 스마트 교육 시스템의 연계점을 연구하고자 한다. 기존 기술의 적용은 안정성과 신뢰성 측면에서 유용하며 새로운 구조의 제안에 있어서 빠른 적용이 가능한 모델로 전개될 수 있다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.3
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• pp.815-834
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• 2012

Recently, along with the innovative development of wireless communication techniques and mobile devices, mobile P2P services in mobile wireless networks have gained a lot of attention. In this paper, we propose a resource discovery scheme with data dissemination over mobile P2P networks. In the proposed scheme, each peer manages a local information table, a resource index table, and a routing table in a local database to enhance the accuracy and cost of resource discovery. The local information table stores the status of a mobile peer, and the resource index table stores the resource information of the neighbor peers via the ranking function. The routing table is used to communicate with the neighbor peers. We use a timestamp message to determine whether or not the resource index table will be changed before the resource information is exchanged. Our ranking function considers the interest and mobility of the mobile peer and prioritizes the resource information transmitted from the neighbor peers. It is shown via various experiments that the proposed scheme outperforms the existing scheme.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.4 no.6
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• pp.1311-1326
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• 2010

Peer-to-peer (P2P) networks consume the most bandwidth in the current Internet and file sharing accounts for the majority of the P2P traffic. Thus it is important for a P2P file sharing application to be efficient in bandwidth consumption. Bandwidth consumption as much as downloaded file sizes is inevitable, but those in file search and bad downloads, e.g. wrong, corrupted, or malicious file downloads, are overheads. In this paper, we target to reduce these overheads even in the presence of high volume of malicious users and their bad files. Sybil attacks are the example of such hostile environment. Sybil attacker creates a large number of identities (Sybil nodes) and unfairly influences the system. When a large portion of the system is subverted, either in terms of the number of users or the number of files shared in the system, the overheads due to the bad downloads rapidly increase. We propose ELiSyR, a file search protocol that can tolerate such a hostile environment. ELiSyR uses social networks for P2P file search and finds benign files in 71% of searches even when more than half of the users are malicious. Furthermore, ELiSyR provides similar success with less bandwidth than other general efforts against Sybil attacks. We compare our algorithm to SybilGuard, SybilLimit and EigenTrust in terms of bandwidth consumption and the likelihood of bad downloads. Our algorithm shows lower bandwidth consumption, similar chances of bad downloads and fairer distribution of computation loads than these general efforts. In return, our algorithm takes more rounds of search than them. However the time required for search is usually much less than the time required for downloads, so the delay in search is justifiable compared to the cost of bad downloads and subsequent re-search and downloads.

• The KIPS Transactions:PartA
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• v.11A no.4
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• pp.257-266
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• 2004

Mobile agents are defined as processes which can be autonomously delegated or transferred among the hosts in a network in order to perform some computations on behalf of the user and co-operate with other agents. Currently, mobile agents are used in various fields, such as electronic commerce, mobile communication, parallel processing, search of information, recovery, and so on. In pure P2P network environment, if mobile agents that require computing resources rashly migrate to another peers without consideration on the peer's capacity of resources, the peer may have a problem that the performance of the peer is degraded due to lack of resources. To solve this problem, we propose resource reservation based load balancing scheme of using RMA(Resource Management Agent) that monitors workload information of the peers and that decides migrating agents and destination peers. In mobile agent migrating procedure, if the resource of specific peer is already reserved, our resource reservation scheme prevents other mobile agents from allocating the resource.

• Journal of Internet Computing and Services
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• v.10 no.4
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• pp.189-198
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• 2009

Unstructured peer-to-peer systems are most commonly used in today's internet. But file placement is random in these systems and no correlation exists between peers and their contents. There is no guarantee that flooding queries will find the desired data. In this paper, we propose to cluster nodes in unstructured P2P systems using the agglomerative hierarchical clustering algorithm to improve the search method. We compared the delay time of clustering the nodes between our proposed algorithm and the k-means clustering algorithm. We also simulated the delay time of locating data in a network topology and recorded the overhead of the system using our proposed algorithm, k-means clustering, and without clustering. Simulation results show that the delay time of our proposed algorithm is shorter compared to other methods and resource overhead is also reduced.

• Korean Journal of Human Ecology
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• v.13 no.3
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• pp.345-359
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• 2004

Self-efficacy is an important variable determining adolescents' behavior. This study was designed to develope a program for improving teens' self-efficacy. The goal of this program was as follows: (1) to improve self-efficacy by enlarge self-knowledge through in- depth search of one's own inner world, (2) to correct one's inferiority impeding one's inner growth, (3) to improve self-efficacy in family relationship, peer relationship, and academic achievement areas. This program consisted of total 6 sessions, supplemented with interpersonal relationships regarding positive family functioning and the impact of peer groups which were found out in recent researches. Specific strategies such as verbal persuasion, mastery experience, vicarious experience and affective arousal were used.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.103-109
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• 2005

Research about P2P system have recently a lot of attention in connection of form that pass early Centralized P2P and is Decentralized P2P. Specially, Structured P2P System of DHT base have a attention to scalability and systematic search and high search efficiency by routing. But, Structured P2P System of DHT base have problem, file can be located only their unique File IDs that although user may wish to search for files using a set descriptive keyword or do not have the exact File ID of the files. This paper propose extended-CAN mechanism that creates File ID of Contents base and use KID and CKD for commonness keyword processing to support keyword search in P2P System of DHT base.