• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.8
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• pp.1760-1768
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• 2004

A P2P is a method that can share and exchange on digital resources through a direct connection on personnel without a central server. In this paper, we apply a P2P technology to a traditional electronic commerce method so that a seller and a customer can perform a commercial transaction through a direct communication. As such a result, we propose a new e-Commerce model on P2P environment to assure fairness in commercial transactions. To achieve our goal, we put an escrow server which is responsible for guarantee fair contents delivery and payment for the contents between a seller and a customer. When a customer buys content, he first obtains reputation values implicating reliability for the content and refers to these values to determine purchase. The proposed scheme, we can improve the reliability for the purchasing content and provide the fairness to both a seller and a customer simultaneously.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.777-780
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• 2007

인터넷 스트리밍 시스템은 스트리밍 소스를 공급하는 미디어 서버와 이로부터 미디어 스트림을 받아 분배하는 스트리밍 서버, 그리고 스트리밍 단말기들로 구성되며, 기존에는 하나의 스트리밍 서버에 다수의 단말기들이 직접적으로 연결되는 방식을 취하고 있다. 이러한 클라이언트-서버 형태의 중앙 구조의 단점을 극복하여 확장성을 제공하기 위해 P2P 스트리밍 시스템에 대한 연구가 최근 들어 진행되고 있다. 그러나 P2P 방식을 이용한 인터넷 스트리밍 시스템을 설계, 구현, 테스트를하기 위해서 많은 비용이 소비되는 현실적인 어려움이 있다. 그러므로 본 논문에서는 P2P 스트리밍 시스템에 대한 다양한 연구 및 실험을 지원하기 위해, P2P 스트리밍 시스템을 정의하고, NS2 시뮬레이션 라이브러리를 이용하여 P2P 스트리밍 시스템 시뮬레이터 P2PStreamSim을 설계 및 구현하였다. 또한 테스트 P2P 스트리밍 시스템을 사례로 적용하여 P2PStreamSim의 동작을 검증하고 성능을 평가하였다.

• Journal of Advanced Navigation Technology
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• v.15 no.6
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• pp.1015-1024
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• 2011

Mobile P2P protocols in ad-hoc networks have gained large attention recently. Although there has been much research on P2P algorithms for wired networks, existing P2P protocols are not suitable for mobile ad-hoc networks because they do not consider mobility of peers. This study proposes a new cluster-based P2P protocol for ad hoc networks which utilizes peer mobility. In typical cluster-based P2P algorithms, each cluster has a super peer and other peers of the cluster register their file list to the super peer. High mobility peers would cause a lot of file list registration traffic because they hand-off between clusters frequently. In the proposed scheme, while peers with low mobility behave in the same way as the peers of the typical cluster-based P2P schemes, peers with high mobility behave differently. They inform their entrance to the cluster region to the super peer but they do not register their file list to the super peer. When a peer wishes to find a file, it first searches the registered file list of the super peer and if fails, query message is broadcasted. We perform mathematical modeling, analysis and optimization of the proposed scheme regarding P2P traffic and associated routing traffic. Numerical results show that the proposed scheme performs much better than or similar to the typical cluster-based P2P scheme and flooding based Gnutella.

• Journal of Internet Computing and Services
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• v.12 no.4
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• pp.157-172
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• 2011

The latest active studies on distributed OLAP to adopt a distributed environment are mainly focused on DHT P2P OLAP and Grid OLAP. However, these approaches have its weak points, the P2P OLAP has limitations to multidimensional range queries in the cloud computing environment due to the nature of structured P2P. On the other hand, the Grid OLAP has no regard for adjacency and time series. It focused on its own sub set lookup algorithm. To overcome the above limits, this paper proposes an efficient central managed P2P approach for a cloud computing environment. When a multi-level hybrid P2P method is combined with an index load distribution scheme, the performance of a multi-dimensional range query is enhanced. The proposed scheme makes the OLAP query results of a user to be able to reused by other users' volatile cube search. For this purpose, this paper examines the combination of an aggregation cube hierarchy tree, a quad-tree, and an interval-tree as an efficient index structure. As a result, the proposed cloud P2P OLAP scheme can manage the adjacency and time series factor of an OLAP query. The performance of the proposed scheme is analyzed by a series of experiments to identify its various characteristics.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.8
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• pp.1783-1789
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• 2004

It is evaluated that there is infinit capability of creating new e business using P2P program. but the research for the method to protect the copyright of digital contents is urgent even for development of the p2p service because the problem of copyright protection for digital contents is not solved. Though this article, it can be induced that reliable contents sharing use to a flow fund by secure settlement architecture, user authentication and contents encryption and then it as the problem of copyright fee is solved, it is able to discontinue which trouble with a creation work for copyright fee and protection it's once again as growth of p2p market, p2p protocal is will be grow into a important protocal of advanced network. In this article, When users send digital contants to each other in internet, we proposed the P2P DRM algorism to offer a security function which using the technology of copyright management to use a AES Algorithm based on PKI.

• Composites Research
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• v.13 no.6
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• pp.1-8
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• 2000

The fabrication Process of $Al_2O_{3p}$/AC8A composites by pressureless infiltration technique and the effects of additive Mg content and volume fraction of particulate reinforcement on mechanical and wear properties were investigated. It was found that the bending strength decreased with increasing volume fraction of $Al_2O_{3p}$ particles. Whereas hardness increased with volume fraction of $Al_2O_{3p}$ particles. The decrement of strength in case of high volume fraction of $Al_2O_{3p}$ particles was attributed to high porosity level. In terms of additive Mg content, $Al_2O_{3p}$/AC8A composites containing around 5~7wt% of additive Mg indicated the highest strength, and hardness values increased with additive Mg contents. Wear resistance of AC8A alloy were improved by reinforcement of $Al_2O_{3p}$ particles especially at high sliding velocity. Wear property of $Al_2O_{3p}$/AC8A composites and AC8A alloy exhibited different aspects. $Al_2O_{3p}$/AC8A composites indicated more wear loss than AC8A alloy at slow velocity region. However a transition point of wear loss was found at middle velocity region which shows the minimum wear loss and wear loss at high velocity region exhibited almost same value as at slow velocity region, whereas wear loss of AC8A alloy almost linearly increased with sliding velocity. It was found that $Al_2O_{3p}$/AC8A composites containing $Al_2O_{3p}$ volume fraction of 20% exhibited abrasive wear surface regardless of sliding velocity and $Al_2O_{3p}$/AC8A composites containing $Al_2O_{3p}$ volume fraction of 40% showed slightly adhesive wear surface at low sliding velocity, and it progressed to severe wear as increasing the sliding velocity.

• Bulletin of the Korean Mathematical Society
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• v.55 no.4
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• pp.1209-1219
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• 2018

We provide a direct proof of the following theorem of Kalton, Hollenbeck, and Verbitsky [7]: let H be the Hilbert transform and let a, b be real constants. Then for 1 < p < ${\infty}$ the norm of the operator aI + bH from $L^p(\mathbb{R})$ to $L^p(\mathbb{R})$ is equal to $$\({\max_{x{\in}{\mathbb{R}}}}{\frac{{\mid}ax-b+(bx+a){\tan}{\frac{\pi}{2p}}{\mid}^p+{\mid}ax-b-(bx+a){\tan}{\frac{\pi}{2p}}{\mid}^p}{{\mid}x+{\tan}{\frac{\pi}{2p}}{\mid}^p+{\mid}x-{\tan}{\frac{\pi}{2p}}{\mid}^p}}\)^{\frac{1}{p}}$$. Our proof avoids passing through the analogous result for the conjugate function on the circle, as in [7], and is given directly on the line. We also provide new approximate extremals for aI + bH in the case p > 2.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.7B
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• pp.728-733
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• 2009

An ubiquitous environment has features like peer-to-peer and nomadic environments. Such features can be represented by peer-to-peer systems and mobile ad-hoc networks. P2P systems and MANETs share similar features, appealing for implementing P2P systems in MANET environment. However, if a P2P system designed for wired networks was applied to mobile ad-hoc environment, its performance was not good enough. Subsequently, this paper proposes a P2P system to improve performance using cross-layer design and the goodness of a node as a peer by using routing metric and P2P metric to choose favorable peers to connect. It also utilizes proactive approach for distributing peer information. The simulation results showed that the proposed system produced better performance in query success rate, query response time and energy consumption by reducing the routing path length.

• Journal of Korea Society of Industrial Information Systems
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• v.11 no.1
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• pp.21-28
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• 2006

This paper describes the design and implementation of video conference system using hybrid type P2P(Peer to Peer). The proposed video conference system has hybrid type P2P architecture based on a client-server and P2P(Peer to Peer), where client-server is used for exchange of account management, client list and status information and P2P is used for the real time video conference. The proposed video conference system decreases the traffic of server, and cuts down the load of a network. Because the multimedia data is decentralized to client by P2P. Also, this system is tested by the multi-party video conference system using communication protocol and application software through high speed networks.

• Journal of the Korea Society of Computer and Information
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• v.13 no.7
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• pp.109-115
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• 2008

In the P2P distributed system, such peers don't always keep on-line status. P2P systems are different from the ordinary systems that such peers are organically operated as the elements of system. In this case, users using P2P system are able to loss the reliability. At this point, many P2P studies are tried to resolve these problems. In this paper, we suggest a P2P search algorithm for multidirectional processing about the resources to be downloading. In existing studies, the loading rate is very high to select new resources supported peer, so we suggest new solution in this study.