• Journal of Communications and Networks
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• v.15 no.2
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• pp.228-239
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• 2013

Peer-to-peer (P2P) systems have proved the most effective and popular file sharing applications in recent years. Previous studies mainly focused on equal service and differentiated service strategies when peers have no initial data before their downloads. For an upload-constrained P2P file sharing system, we model both the equal service process and the differentiated service process when the initial data distribution of peers satisfies some special conditions. Moreover, we show how to minimize the time required to distribute the file to any number of peers. The proposed fluid-based models can reveal the intrinsic relations among the initial data amount, the peer set size, and the minimum last finish time. The closed-form expressions derived from the extended models can closely approximate chunk-based models and systems, especially for relatively large files. As an application of the extended models, we show how to provide differentiated service efficiently to multiple peer sets. Since no limits are imposed on the upload bandwidth of peers or the size of each peer set, we believe that our analytic process and the results achieved can provide not only fundamental insights into bandwidth allocation and data scheduling but also a helpful reference for both improving system performance and building an effective incentive mechanism for P2P file sharing systems.

• 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.

• Journal of Korea Multimedia Society
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• v.12 no.5
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• pp.717-727
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• 2009

P2P (Peer-to-Peer) network depends on cooperation of peers considerably. However, some peers do not share files at all and only download files. Peers also share low quality files or unpopular files. These selfish behavior of peers is referred to 'free riding'. The free riding of peer may decrease participation of other peers or the system performance. In this paper, we propose an incentive mechanism, called IcMFS (Incentive Mechanism for File Sharing System), which provides the correct use of incentive mechanism using trust peer, computes contribution values referring behavior of peers and rewards peers. The proposed mechanism assigns bandwidth and TTL(Time-To-Live) to a peer and differentiates the use of service. A case study on simulations shows the service differentiation according to the contribution value of peer, the correct use of incentive mechanism using trust peer and the advantage by use of trust peer. To prove the stability of proposed mechanism, we also show the disadvantage that a peer receives from the incorrect use of incentive mechanism.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.3
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• pp.286-290
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• 2008

As the number of mobile device users increases, many researches on peer-to-peer(P2P) systems in mobile environments have been carried out. In this paper, we propose a couple of double-layered P2P file sharing systems to overcome the 'flooding' problem in previous mobile P2P systems. We classify peers into two groups, super peers and sub-peers to establish new routing tables. A super peer manages its sub-peers in the systems. The first proposed system partitions the service area into small cells, each of which is a square. Each super peer is located near the center of the square. The second system selects super peers which have the largest number of adjacent peers. As file transmission and file searches are managed mainly by super peers, unnecessary multi-broadcasting could be avoided. The experimental results show that the proposed systems outperform a typical file sharing system in terms of the amount of message traffic with about $1.2{\sim}1.6$ times improvement on the average.

• Journal of the Korea Computer Industry Society
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• v.4 no.12
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• pp.873-886
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• 2003

Lookup Is one of important factors for network traffic on peer-to-peer network. Especially, large amount of network resources are required for lookup process in p2p file sharing system that clients use the dynamic If and they import to p2p network in random. In this paper, we employ efficient lookup mechanism which searches lookup with the combined information of ISP key values and the extracted key values from SHA-1 hashing function for shared contents id. The proposed mechanism efficiently searches files on the network because the mechanism processes P2P lookup with consideration the routing information of ISP. We suggest the adapted simulation environment based upon the famous file sharing system of emule P2P and experiment the proposed system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.1B
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• pp.73-85
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• 2004

SIn this paper, we introduce our experience for designing and implementing new concept of a global XML-based Peer-to-Peer (P2P) engine to support various P2P applications, and interconnection among PC, Web and mobile computing environments. The proposed P2P engine can support to heterogeneous data exchanges and web interconnection by facilitating with the text-base XML while message exchange are necessary. It is also to provide multi-level security functions as well as to apply different types of security algorithms. The system consist of four modules; a message dispatcher to scheduling and filtering the message, a SecureNet to providing security services and data transmission, a Discovery Manager to constructing peer-to-peer networking, and a Repository Manager to processing data management including XML documents. As a feasibility test, we implement various P2P services such as chatting as a communication service, white-board as an authoring tool set during collaborative working, and a file system as a file sharing service. We also compared the proposed system to a Gnutella in order to measure performance of the systems.

• Journal of Korean Society for Quality Management
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• v.34 no.2
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• pp.33-47
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• 2006

This study was designed to examine the casual relationships among trust evaluation factors, trust, customer satisfaction, and re-use intention in the P2P file sharing service. We applied structural equation model to test the hypotheses and research model. As a result of this study, trust evaluation factors affect trust and customer satisfaction and both of trust and customer satisfaction affect re-use intention respectively and significantly. Also trust affects customer satisfaction significantly. Specifically, trust was empirically confirmed as one of the important factors preceding customer satisfaction and re-use intetion in the P2P file sharing service. Therefore, this study shows that trust is important factor that P2P companies have to emphasize to raise user satisfaction and performance.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.384-387
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• 2003

In this paper, we have designed the integrated wire and wireless P2P framework using mobile agents to share efficiently resources as media file. Most of the P2P applications are used on the wire network. We propose the integrated wire and wireless P2P framework. Proposed P2P platform is based on JXTA of Sun Microsystems. But JXTA is pure peer-to-peer network model, so it sends message other peers as broadcast style to request resources. In this way, there are some problems as massage overload, bandwidth loss, etc. In order to solve this problem, we propose a hybrid peer-to-peer network model using mobile agent. Proposed scheme also solve existing hybrid pEp model's flaws which have the delay and low rate due to concentrated server. In proposed scheme, mobile agents that have autonomy and mobility are used to search the location of resources. Besides, mobile agents could solve the loss problem of the search result. To improve P2P QoS(Quality of Service), we could monitor peer's state information using PIP(Peer Information Protocol) of JXTA.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.15 no.4
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• pp.61-70
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• 2005

We propose and implement a flexible secure peer-to-peer(P2P) file sharing scheme which can be used for data sharing among closed user group (CUG) members. When a member wants to share data, notification messages are sent to the members with whom the member wants to share data. Each notification message includes one-time password encrypted with the receiver's public key. A member who received the notification message can download the data by using the one-time password. The proposed scheme provides selective sharing, download confirmation and efficient storage management. In terms of security, the proposed scheme supports authentication, entity privacy, replay attack protection and disguise prevention. We also implement the proposed system and find that the system is very useful among P2P service of closed user groups.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.4
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• pp.103-109
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• 2008

Many Internet application provide the PKI(public key infrastructure)-based service to provide authentication and message integrity. Several researchers proposed PKI-based p2p network framework. However, in the real world, the use of PKI is not suitable for peer to peer network, because the peer-to-peer network is an open and dynamic network. Moreover, currently there is no nation-to-nation interoperable certificate. In this paper, we designed reliable p2p file sharing application without public key infrastructure. To do this we propose reliable public key distribution mechanism to distribute public key safely without PKI infrastructure for two-tier super-peer architecture. In our system, each peer generates and distributes its public/private key pairs, and the public key is securely distributed without PKI. The proposed mechanism is safe against MITM attack. This mechanism can be applied various P2P applications such as file sharing, IPTV, distributed resource sharing and so on