• Journal of Broadcast Engineering
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• v.24 no.2
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• pp.251-263
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• 2019

Recently the huge demand for Internet media streaming has dramatically increased the cost of the CDN (Content Delivery Network) and the need for a means to reduce it is increasing day by day. In this situation, a P2P-assisted DASH technology has recently emerged, which uses P2P (Peer-to-Peer) communications based on WebRTC (Web Real-Time Communication) standards to reduce the CDN cost. This paper proposes an algorithm that can significantly improve CDN cost savings in this technology by selecting peers based on the transport history. Also we implemented this algorithm in an experimental system and, after setting experimental conditions that emulate the actual mobile network environment, we measured the performance of the experimental system. As a result, we demonstrated that the proposed algorithm can achieve higher CDN cost savings compared to the conventional algorithm where peers are selected at random.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.11
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• pp.2166-2171
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• 2007

In this paper, we proposed a Sequential Download System(SDS) to provide high steaming QoS in p2p network. SDS is able to receive a media file simultaneously from multiple source peer by download manager and deal with unexpected leave of source peer. Also It can provide stable streaming services with minimum buffering delay and manage request of other peer by memory map in process of downloading.

• Journal of Korea Multimedia Society
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• v.10 no.10
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• pp.1328-1337
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• 2007

We describe a method for streaming specific section using the section information among peers on P2P network. As peers tend to extract only the part of contents in which they are interested, an indexed file is created based on the section information of multimedia contents and registered in the search server. If a peer requests the streaming of specific parts of the contents to other corresponding peer using the section information that the server returns, the peer streams only separated section of the multimedia contents according to the information. For this process, we implement a function that a peer's PC can play a role as a server, and the peer streams the separated content based on the section information that the server supplies.

• Proceedings of the Korea Society for Simulation Conference
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• 2005.05a
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• pp.139-143
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• 2005

The P2P is a network environment supporting data exchange which is directly connected peers without limit of existing server-client and intervening central server for resource or offered service with each peer. JXTA is a representative of P2P system. JXTA is a typical distributed computing model that proposed by Sun Microsystems. JXTA that doesn't require centralized services or resources is adaptable in extreme changes of network organization. MANET(Mobile Ad Hoc Network) is a representative wireless network that is composed of mobile nodes without infrastructure. So MANET establishes the path for the communication of each peers and maintains the newest routing information by exchanging routing information. In this paper, we propose a technique of JXTAMAUET which implements JXTA which is the P2P network system from the wireless network which is becoming the foundation of ubiquitous computing. For the performance evaluation of the JXTAMANET, we use simulation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.662-665
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• 2011

The cognitive radio (CR) network has been studied in the form of open source by vast number of communities, and the potential expectation is very high since the CR is based on reprogrammable platform. However, this characteristics of open-source software take high risk as well. As the peer-to-peer software has been abused, so high is the chance that the CR network can be abused public wide. Consequently, the benefit from the study of next-generation wireless network can be at risk because of the negative impact of violation of communication law or abusing the CR. In this contribution, we analyze the issues and the problems of the CR and discuss an efficient measure against security attacks.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.8
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• pp.1486-1492
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• 2007

Searching distributed resources efficiently is very important in distributed computing environments like P2P. But distributed resource searching may have system overheads and take a lot of time in proportion to the searching number, because distributed resource searching has to circuit many peers for searching information. In this paper, we design a proxy peer algorithm based on DHT(Distributed Hash Table) for efficient distributed resource searching in JXTA network environments. By containing the rendezvous information in proxy peer and searching a rendezvous peer firstly which has higher hit ratio, we can reduce the searching number and minimize system overheads.

• Journal of Ocean Engineering and Technology
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• v.11 no.4
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• pp.180-188
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• 1997

This paper proposes a new efficient MAC(Media Access Control) protocol to establish the ultrasonic communication network for underwater vehicles, which ensures a certain level of maximum throughput regardless of the propagation delay of ultrasonic and allows fast data transmission through the multiple ultrasonic communication channel. A MAC protocol for underwater communication network that allows 'peer-to-peer' communication between a surface ship and multiple underwater systems is designed, and the proposed control protocol is implemented for its verification.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2005.11a
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• pp.161-164
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• 2005

Mobile device users are sensitive to pay telecommunication charge for downloading Internet data, because the cost is proportional to the amount of data received. If there are device users who want to download the same content, they may cooperate each other to form an ad hoc network and share the partially downloaded content in order to reduce the amount of data downloaded. Each mobile device, called a peer, downloads a specific portion of the whole content using fee-based telecommunication channel, and exchanges the portion with other peers with free ad hoc channel in order that all participating peers are able to reconstruct the whole content in this situation, al1 participating peers become senders and receivers at the same time. In order to distribute the partial content to other peers, the ad hoc network requires a control led distribution mechanism. This paper introduces the per-peer-based distribution method in which one designated peer can transmit partial data to its neighbors at a time. Simulation results show that 90$\%$ of the telecommunication cost is saved with as few as 10 peers .

• Journal of Advanced Navigation Technology
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• v.15 no.6
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• pp.1138-1142
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• 2011

This paper proposes the Alert System, the purpose of which is to detect an accident and to take care of it quickly in a working place. In the previous studies, a wireless network system was suggested using 'Star Topology'. However, this study constructs the wireless network system of Peer-to-Peer Topology, which allows to build more efficient network for communication. Also, with this system it is possible to check other the worker's situation through double sensing with Temperature/Gas sensor and Inclination sensor. In order to take action quickly, the Alert System is using a monitoring program which visualizes a worker's situation and the area where an accident occurs.

• Journal of Information Processing Systems
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• v.16 no.3
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• pp.699-717
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• 2020

Propagation time on permissionless blockchain plays a significant role in terms of stability and performance in the decentralized systems. A large number of activities are disseminated to the whole nodes in the decentralized peer-to-peer network, thus causing propagation delay. The stability of the system is our concern in the first place. The propagation delay opens up opportunities for attackers to apply their protocol. Either by accelerating or decelerating the propagation time directly without proper calculation, it brings numerous negative impacts to the entire blockchain system. In this paper, we thoroughly review and elaborate on several parameters related to the propagation time in such a system. We describe our findings in terms of data communication, transaction propagation, and the possibility of an interference attack that caused an extra propagation time. Furthermore, we present the influence of block size, consensus, and blockchain scalability, including the relation of parameters. In the last session, we remark several points associated with the propagation time and use cases to avoid dilemmas in the light of the experiments and literary works.