• KSII Transactions on Internet and Information Systems (TIIS)
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• v.4 no.5
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• pp.709-735
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• 2010

The reciprocal virtue of peer-to-peer networking has stimulated an explosion of peer population and service capacity, ensuring rapid content distribution in peer-to-peer networks. Critical issues such as peer churn, free riding, and skewed workload significantly affect performance results such as service agility, fairness, and resource utilization. To resolve these problems systematically, this study proposes a peer assignment scheme that supports fair peer-to-peer file sharing applications. The proposed scheme exploits the peer duality of both server-oriented peer capacity and client-oriented peer contribution. Accordingly, the system server can prioritize download requests and appropriately assign server peers to uploading file objects. Several functional extensions, including peer substitution and elimination, bandwidth adjustment, and distributed modification, help cope with subtle situations of service starvation and download blocking, and hence make the system design robust and amenable. Simulation results show this design is examined under both centralized and distributed peer-to-peer environments. Performance results confirm that the proposed mechanisms are simple but effective in maintaining service agility and fairness, without loss of overall service capacity in peer-to-peer files sharing systems.

• Proceedings of the Korea Multimedia Society Conference
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• 2001.06a
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• pp.481-487
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• 2001

본 논문은 현재까지 제시되어진 peer to peer network model들을 정리하고 대표적인 peer to peer network model에 지문인식을 적용하여 개인에 대한 신원 인증 절차를 수행함으로써 보안에 대한 새로운 해결책을 제안하였다. 기존의 peer to peer network model은 개인 대 개인간의 효율적인 network검색 기능과 분산 computing 환경을 제공하지만 보안에 관해서는 아직까지도 많은 연구가 필요하다. 본 연구에서는 기존의 peer to peer network model들에 지문인식을 사용한 새로운 보안 model을 설계하였다.

• Korean Journal of Child Studies
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• v.23 no.5
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• pp.51-64
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• 2002

In this study of the correlates of peer victimization, 584 $4^{th}$ grade children in Seoul answered questionnaires regarding their personality traits, parent attachment and the marital conflict of their parents. Subjects and their peers also reported on peer aggression and victimization by peers. Data were analyzed by partial correlation, controlling for gender. Children's sociability/activity related positively to peer-rated peer aggression and negatively to self- and peer-rated victimization by peers. Children's shyness/emotionality related positively to self-reported peer aggression and to self- and peer-rated victimization by peers. Parent attachment related negatively to self-reported peer aggression and victimization by peers and positively to peer-rated peer aggression. Marital conflict related positively to self-reported peer aggression and to self- and peer-rated victimization by peers. Marital conflict was the most influential on peer aggression and children's personality traits were on victimization by peers.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.292-294
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• 2005

The emerging peer-to-peer (P2P) model has recently gained a significant attention due to its high potential of sharing various resources among networked users. Super-peer unstructured P2P systems have been found very effective by dividing the peers into two layers, super-peer and edge peer. Super peer deal with all Queries instead of edge peers. The existing P2P systems assume all super peers have equal roles and capabilities. However, all super peers don't so that edge peers should select the best super peer in order to handle Queries well. In this paper, we suggest the ISP2P (Intelligent Super-peer based P2P) which allows to select the best super peer to the edge peers. We classify super peers according as the capacity of a edge peer to a super peer. We show that considering the quality of a edge peer to a super peer can improve the performance of the response time and bandwidth.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.11a
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• pp.932-935
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• 2007

모바일 기기 사용이 급증함에 따라 모바일환경에서 이루어지는 P2P방식 연구가 활발히 진행되고 있다. 본 논문에서는 기존의 모바일환경에서의 P2P방식이 지닌 peer들 사이의 multi-broadcasting 방식의 문제점을 보완하고, 새로운 routing table을 구축하기 위해 peer들을 2개의 계층으로 구분하였다. 즉, peer들을 super peer들과 각 super peer에 의해 관리되는 sub peer들로 구분하였다. 파일의 탐색과 전송은 super peer들이 관리하므로, 기존의 불필요한 multi-broadcasting 방식을 피할 수 있다. 본 논문에서는 분산 네트워크를 위한 peer의 계층화 작업을 설계하였다. MIS(Maximal Independent Set)알고리즘을 이용하여 peer들의 계층화 작업을 외부의 도움 없이 peer들간의 통신으로 할 수 있게 만들었다. 이처럼 peer들을 super peer와 sub peer로 구분하면 불필요한 broadcasting을 피할 수 있어 시스템 성능이 향상되며, 이를 실험을 통하여 증명하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.3
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• pp.528-534
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• 2007

As XML is becoming a standard for representation and exchange of abundant information on the Web, solutions for a secure and selective dissemination of XML data, known as SDI, are strongly demanded. Such trends are more outstanding especially in distributed heterogeneous environment such as Peer-to-Peer. Although many approaches have been proposed to provide secure and efficient SDI mechanisms, almost previous approaches have focused only on filtering with user profile and they adopt center-oriented administration approaches. It is therefore difficult to adapt them directly to the distributed Peer-to-Peer environments characterized by dynamic participation. In this paper, we develop a novel dissemination method, which makesuse of authorization policy and secret sharing scheme. It provides more secure, scalable means for XML dissemination on Peer-to-Peer networks.

• The Korean Journal of Elementary Counseling
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• v.7 no.1
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• pp.185-203
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• 2008

This study aimed at examining an effect of peer counselor's mentor activity on rejected children's peer relationship in elementary school. To achieve this goal, the following hypothesis was made. Hypothesis I : Peer counselor's mentor activity will improve rejected children's peer relationship. I -1 : Peer counselor's mentor activity will improve rejected children's trust to peer. I -2 : Peer counselor's mentor activity will improve rejected children's respect to peer. To test the hypothesis, after sociometry papers 19 fifth-graders for rejected children groups were selected from four classes at H elementary school in Busan according to Coie & Dodge's(1988) five classified system that is modified to Korean situation by Ahn ie-hwan(2006). Ten rejected students from two classes were labeled as a peer group with a peer counselor and nine rejected students who had similar characteristics from two classes were labeled as an non-peer group without a peer counselor. The peer counselors were decided by obtaining affirmative mentions of rejected students group. Peer counselors participated in the training of peer counselor's skill program and then they had a person to person mentor activity with the rejected children's group that they belonging to. The training consisting of a total of four sessions, 3 times a week, was provided to peer counselors eleven times after school. The peer counselors given the peer counselling training did person to person mentor activity with the peer group's rejected children for a month. The mentor activity, three times a week, following during training was reinforced after school. For peer counselor training, the elementary school children's peer counseling program developed by Lee Sang-hi, Roh Seong-deok and Lee Ji-eun(2001) was used. Hong Ok-soon's(1984) peer relationship test, Moreno's(1934) sociometry tool were used to verify an effect of the peer counselor's mentor activity. For the data analysis, quantitative analysis with sociometry tool and qualitative analysis with social status and social type change were used. To know the difference in pre test and post test peer relationship between experimental group and control group, in quantitative analysis, ANCOVA result was used and qualitative analysis, social status and social type was used. The finding was as followings. First, after peer counselor's mentor activity, there was a significant improvement in rejected children's trust and respect to peer and the whole relationship from the pretest to the post test. Second, peer counselor's mentor activity gave rise to affirmative changes on rejected children's social status and social type. This study concluded that peer counselor's mentor activity would help rejected children's peer relationship to change affirmatively and improve.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.11
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• pp.471-474
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• 2013

In this paper, we propose a distributed parent peer selection method to construct an efficient peer-to-peer(P2P) network topology by considering the capacity of a peer and the hop distance from a data source to the peer. To achieve this goal, we propose a method to combine the two performance metrics to calculate the probability that a peer becomes a parent peer. Using the probability, we propose a method to select a parent peer stochastically by making use of the state information of the neighboring peers that each peer maintains. Through simulation studies, we show that the proposed method drives high capacity peers to support more children peers and makes the diameter of the P2P network shorter than the other methods.

• Journal of Advanced Navigation Technology
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• v.15 no.4
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• pp.632-639
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• 2011

Searching distributed resource efficiently is very important in distributed computing, cloud computing environment. Distributed resource searching may have system overheads and take much time in proportion to the searching number, because distributed resource searching has to circuit many peers for searching information. The open-source community project JXTA defines an open set of standard protocols for ad hoc, pervasive, peer-to-peer computing as a common platform for developing a wide variety of decentralized network applications. In this paper, we proposed peer search algorithm based on JXTA-Sim. original JXTA peer searching algorithm selected a loosely-consistent DHT. Our Lookup algorithm decreases message number of WALK_LOOKUP and reduce the network system overload, and we make a result of same performance both original algorithm and our proposed algorithm.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.6
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• pp.65-73
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• 2016

Peer-to-Peer (P2P) systems with super-peer overlay networks show combined advantages of both hybrid and pure P2P systems. Super-peer is a special peer acting as a server to a cluster of generic peers. Organizing a super-peer network is one of important issues for P2P systems with super-peer networks. Conventional P2P systems are based on two-level hierarchies of peers. One is a layer for generic peers and the other is for super-peers. And it is usual that super-peer networks have forms of random graphs. However, for accommodating a large-scale collection of generic peers, the super-peer network has also to be extended. In this paper, we propose a scheme of hierarchically constructing super-peer networks for large-scale P2P systems. At first, a two-level tree, called a simple super-peer network, is proposed, and then a scheme of generalizing and then extending the simple super-peer network to multi-level super-peer network is presented to construct a large-scale super-peer network. We call it an extended super-peer network. The simple super-peer network has several good features, but due to the fixed number of levels, it may have a scalability problem. Thus, it is extended to k-level tree of a super-peer network, called extended super-peer network. It shows good scalability and easy management of generic peers for large scale P2P system.