• Proceedings of the Korean Information Science Society Conference
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• 2006.06a
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• pp.415-417
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• 2006

분산형 P2P 그리드 시스템을 구축하는데 있어 연산 수행을 위한 노드 구성 기법과 구성된 토플로지에 적합한 연산 수행 보델 및 스케줄링 기법은 필수 요소이다. 하지만 기존 연구에서는 자원 제공자와 휘발성을 고려하지 않은 연산 수행 모델을 사용하였기 때문에 연산의 안정적인 수행이 보장되지 못하고, 시스템의 성능이 떨어지는 문제점이 발생한다. 이에 본 논문에서는 가용성 기반의 자가 조직적 계산 오버레이 네트워크(SelfCON:Self-organizing Computation Overlay Network) 구성 기법과 구성된 토폴로지에 적합한 연산 수행 모델 및 스케줄링 기법을 제안한다. 제안 기법은 자원 제공자 노드의 휘발성을 고려하여 안정성을 높임으로써 전체 연산 성능을 향상시킨다.

• Journal of Digital Contents Society
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• v.14 no.1
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• pp.89-95
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• 2013

Many peer-to-peer (p2p) systems have been studied in distributed, ubiquitous computing environments. Distributed hash table (DHT)-based p2p systems can improve load-balancing even though locality utilization and user mobility are not guaranteed. We propose a mobile locality-based hierarchical p2p overlay network (MLH-Net) to address locality problems without any other services. MLH-Net utilizes mobility features in a mobile environment. MLH-Net is constructed as two layers, an upper layer formed with super-nodes and a lower layer formed with normal-nodes. The simulation results demonstrate that MLH-Net can decrease discovery routing hops by 13% compared with JXTA and 69% compared with Chord. It can decrease the discovery routing distance by 17% compared with JXTA and 83% compared with Chord depending on the environment.

• Journal of KIISE:Information Networking
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• v.34 no.2
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• pp.88-99
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• 2007

P2P systems are distributed data sharing systems, and each node in them plays the role of client as well as server. There are several studies using Distributed Hash Table, such as Chord, CAN, Tapestry, Pastry, but these systems don't consider the physical latency, therefore they have a weakness of difficulty to guarantee stable performance. To improve this problem, we present the TP2P system. This system is a self-organizing hierarchical overlay system and it uses Chord routing mechanism for lookup data. This system is organized by several subnets, each subnet is organized by physically close nodes, and global network organized by all nodes. In each subnet, one node finds a data, it saves in a node in the subnet, therefore it has higher probability to reduce physical lookup latency than Chord system. And each node has global information of some nodes in its subnet, and it is used to lookup data, therefore the number of hops decrease about 25% as well as the physical lookup latecy are reduced.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.5
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• pp.211-216
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• 2011

Networked virtual environments (NVEs) are distributed systems where geographically dispersed users interact with each other in virtual worlds by exchanging network messages. Massively Multiplayer Online Game (MMOG) is one of diverse applications where more than hundreds of users enjoy experiencing virtual worlds. A limited area called area of interest (AOI) in MMOG is reduced the load caused by message exchange between users. Voronoi-based Overlay Network (VON) is proposed to reduce the bandwidth consumption in P2P environments and Vorocast also is made using message forwarding in VON. We propose a dynamic AOI management method that solves problems such as a consistency and latency due to forwarding position updates to neighbor nodes from the message originator in forwarding scheme. Our scheme provides the consistency and reduces latency by combining direct connection scheme and Vorocast scheme compared to existing schemes. The communication between a user and users existing in center circle within AOI of the user is directly connected and the communication between the user and users existing outside the center area within AOI is using Vorocast scheme. The proposed model is evaluated through simulations.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.116-119
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• 2009

In this paper, a P2P streaming system for community TV service which requires realtime interactions was designed and implemented. The proposed system constructs a short delay tree-based P2P network in order to effectively support various community TV services within end-to-end delay bounds. Because a community service based on conversation requires a short delay. The P2P network of this paper was constructed by using an algorithm which utilizes locality and delay information. The implemented P2P streaming system is composed of a Web server and a application, each of which was implemented using Asp.Net and C#.Net respectively.

• Journal of Korea Multimedia Society
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• v.13 no.1
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• pp.38-46
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• 2010

A stable game managing system is absolutely needed to accept simultaneous interlacing of many users for on- line game system. The proposed P2P on-line game system in this paper is able to get stable and real-time game managing within limited time stamp utilizing through reorganizing peers according to synchronous time which can be avoid congestion on one region, it is possible to synchronize for game nodes within limited time stamp utilizing. Reorganizing M-tree which leads 10 distribute loads. The system manages each region unit, and it is execute no matter how big game sizes are. Thus to ensure such as the problems of expand server and stabilization or message transmission. Also, prove efficiency of the suggested system through the simulation.

• The KIPS Transactions:PartC
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• v.16C no.2
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• pp.245-256
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• 2009

Pastry overlay network is one of structured P2Ps using DHT(Distributed Hash Table). To reduce the number of messages among nodes, Rosary and LAR have been proposed by exploiting spatial locality and caching, respectively, in the Pastry. Rosary consists of Inter-Pastry and Intra-Pastry. A root node is assigned as a representative in each Intra-Pastry and it has the responsibility of Inter-Pastry and Intra-Pastry routing. Therefore, Rosary has several disadvantages; 1) low fault tolerance in case of root node failure 2) routing hop count increases because of the use of root nodes compared to the existing structured P2Ps, and 3) the communication load is concentrated in some specific areas. LAR has inefficient problems in that caching is not distributed among nodes in Intra-Pastry and caching is used by only nodes in the Intra-Pastry. In this paper, we propose an improved Pastry called Doughnut to overcome the above problems of Rosary and LAR. By dividing nodes with the local characteristics, the Doughnut consists of Inter-Pastry and Intra-Pastry, and all nodes have the responsibility of Inter-Pastry and Intra-Pastry routing. This results in that all nodes perform the role of the existing root node. This solves the problems of the reducing of fault-tolerance, the increasing of routing hop count, and the not-distributed communication load. Also Doughnut can use cache effectively because it guarantees the even cache distribution in local(Intra-Pastry) and the cache contents in local can be used in the other local. The proposed algorithm is implemented using simulator and the experimental results show the effectiveness of the proposed method compared to the existing method.

• 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.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.11a
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• pp.682-685
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• 2007

P2P 기술의 발달로 기존 클라이언트-서버 형태인 중앙 집중형 방식의 단점을 극복하고 있다. 이러한 P2P 기술의 진화로 P2P 응용 기술에 대한 많은 발전이 있었다. 현재 P2P 구조에서 사용자는 P2P 네트워크에 참여하여 자신이 원하는 자료를 찾는 검색과정이 필요하다. 본 논문은 이러한 과정을 최소화하여서 검색과정을 줄일 수 있는 방법을 다룬다. P2P 네트워크에 존재하는 서비스 프로파일 목록들을 서비스를 제공하는 주체가 서비스를 소비하는 주체에게 보내주게 된다면 사용자는 최신의 서비스 목록을 유지하여 서비스 목록 검색 시간을 최소화 시킬 수 있다. 본 논문에서는 P2P 오버레이 네트워크상에서의 서비스 푸시 시스템에 대한 정의, 각 피어들의 행동모델을 정의 및 시스템 설계에 대해서 소개한다.

• KIPS Transactions on Computer and Communication Systems
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• v.1 no.2
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• pp.99-102
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• 2012

The performance of P2P application services may be improved by reducing unnecessary inter-network traffic through intelligent peer selection. However, since a logical link between peers in a P2P overlay network is composed of a set of physical links in an underlay network, the traffic pattern determined by the sending rates of selected peers imposes loads on each underlay links. Thus, if the sending rates are not determined carefully, the loads between underlay links may not be balanced, which means some links are underloaded while the other links are congested. In this paper, we take an optimization approach to determine the sending rates of peers strategically to avoid the inefficient use of underlay links. The proposed scheme also guarantee the minimum receiving rates of peers while minimizing the maximum link utilization of underlay links, which is beneficial both to P2P applications and an underlay network.