• Journal of Communications and Networks
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• v.11 no.3
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• pp.211-228
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• 2009

After clarifying the underlying problems in a secure network storage, we introduce two important requirements, leakageresilience and availability in higher levels respectively, for data keys that are used to protect remotely-stored data. As a main contribution of this paper, we give a new security layer for overlay networks by proposing a leakage-resilient authentication and data management system. In this system, we specifically propose a single mode and a cluster mode where the latter provides a higher level of both leakage-resilience and availability for the data key.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.10
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• pp.5013-5034
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• 2019

In the Peer-to-Peer (P2P) streaming systems, peers randomly form a network overlay to share video resources with a data scheduling scheme. A data scheduling scheme can have a great impact on system performance, which should achieve two optimal objectives at the same time ideally. The two optimization objectives are to improve the perceived video quality and maximize the network throughput, respectively. Maximizing network throughput means improving the utilization of peer's upload bandwidth. However, maximizing network throughput will result in a reduction in the perceived video quality, and vice versa. Therefore, to achieve the above two objects simultaneously, we proposed a new data scheduling scheme based on multi-objective particle swarm optimization data scheduling scheme, called MOPSO-DS scheme. To design the MOPSO-DS scheme, we first formulated the data scheduling optimization problem as a multi-objective optimization problem. Then, a multi-objective particle swarm optimization algorithm is proposed by encoding the neighbors of peers as the position vector of the particles. Through extensive simulations, we demonstrated the MOPSO-DS scheme could improve the system performance effectively.

• Journal of Communications and Networks
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• v.7 no.1
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• pp.76-86
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• 2005

Today's wireless access networks consist of several tiers that overlap each other. Provisioning of real time undisrupted communication to mobile users, anywhere and anytime through these heterogeneous overlay networks, is a challenging task. We extend the end-to-end approach for the handoff management in hybrid wireless data network by designing a fully mobile-controlled handoff for mobile devices equipped with dual mode interfaces. By handoff, we mean switching the communication between interfaces connected to different subnets. This mobile-controlled handoff scheme reduces the service disruption time during both horizontal and vertical handoffs and does not require any modification in the access networks. We exploit the IP diversity created by the dual interfaces in the overlapping area by simultaneously connecting to different subnets and networks. Power saving is achieved by activating both interfaces only during the handoff period. The performance evaluation of the handoff is carried out by a simple mathematical analysis. The analysis shows that with proper network engineering, exploiting the speed of mobile node and overlapping area between subnets can reduce service disruption and power consumption during handoff significantly. We believe that with more powerful network interfaces our proposal of dual interfaces can be realized.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.5 s.347
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• pp.1-6
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• 2006

By comparing video-overlay method where digital and SCM signal are modulated in different optical source, we experimentally investigated the performance of simultaneous modulation of data and broadcasting signals using a single LD for broadcasting in PON based optical access network. The experimental results show that by increasing the minimum value of injected current for LD modulation above about 1.5 times of threshold current of LD, data and broadcasting signals can modulate without mutual interference. We also proposed and demonstrated the scheme of optical transmitter optimized for simultaneous modulation of data and broadcasting signals where anode and cathode of LD are separately used as signal interface for data and broadcasting signals, respectively.

• Information and Communications Magazine
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• v.13 no.3
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• pp.61-70
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• 1996

In this paper, the architecture of the LAN Emulation service defined by the ATM Forum is introduced. In order to use the vast base of the existing LAN application software in ATM network. LAN Emulation provides a MAC layer service emulating connectionless services of legacy LANs on ATM networks. LAN Emulation forms a logical overlay network, called and emulated LAN, on top of an ATM network. LAN Emulation service comprises a set of LAN Emulation Clients(LECs) residing in end stations of an emulated LAN and three logical service entities : LAN Emulation Configuration Server (LECS), LAN Emulation Server(LES). and Broadcast and Unknown Server(BUS). LEC utilizes the services provided by these three servers to provide seamless interworking between legacy LANs and ATM networks, and to support transparent communications between LAN applications over ATM.

• 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.

• Spatial Information Research
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• v.17 no.3
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• pp.251-259
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• 2009

As a result of the current trend towards promoting conservation of the ecosystem, there have been various studies conducted to determine ways to establish an ecological network. The development of analytical methods and an environmental database of GIS has made the creation of this network more efficient. This study focuses on the development of an urban spatial decision support system based on 'Landscape Ecology Theory'. The spatial decision support system suggested in this study consists of four stages. First, landscape patch for the core areas, which are major structures of the ecological network, was determined using the GIS overlay method. Second, a forest habitat was investigated to determine connectivity assessment. Using the gravity model, connectivity assessment at the habitat forest was conducted to select the needed connecting area. Third, the most suitable corridor routes for the eco-network were presented using the least-cost path analysis. Finally, a brief investigation was conducted to determine the conflict areas between the study result and landuse. The results of this study can be applied to urban green network planning. Moreover, the method developed in this study can be utilized to control urban sprawl, promote biodiversity.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.18 no.5
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• pp.13-26
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• 2015

Urban park and green space provide various functions. Among the functions, human benefit and increase of biodiversity are known to be important. Therefore, it is important to consider human and biotic aspect in the process of selecting suitable site for park and green space. However, there is insufficient research on both aspects. In this study, we used green network to analyze human and biotic aspect to select suitable site for park and green space in Seongnam City in Korea. To analyze the green network, we used accessibility for human aspect and used dispersal distance and habitat size for biotic aspect. We conducted least-cost path modelling using movement cost. In case of biotic aspect, GFS (generic focal species) is used to estimate habitat size and dispersal distance. To find out suitable site for park and green space, we used an overlay analysis method. As the result, old residential areas are shown have insufficient green network which needs park and green space. Furthermore, the green network for biotic aspect is insufficient in old residential areas comapred to green network for human aspect. The result of this study could contribute in planning of park and green space to maximize their functions.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.20 no.3
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• pp.43-52
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• 2010

The Kad network is a peer-to-peer (P2P) network which implements the Kademlia P2P overlay protocol. Nowadays, the Kad network has attracted wide concern as a popular architecture for file sharing systems. Meanwhile, many problems have been coming out in these file sharing systems such as freeriding of users, uploading fake files, spreading viruses, and so on. In order to overcome these problems, we propose an incentive mechanism based on game theory, it establishes a more stable and efficient network environment for Kad users. Users who share valuable resources receive rewards by increasing their credits, while others who supply useless or harmful files are punished. This incentive mechanism in Kad network can be used to detect and prevent malicious behaviors of users and encourage honest interaction among users.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.11
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• pp.1-11
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• 2009

A content based pub/sub (Publish/subscribe) services at the peer-to-peer network has the requirements about how to distribute contents information of subscriber and to delivery the events efficiently. For satisfying the requirements, a DHT(Distributed Hash Table) based pub/sub overlay networking and tree type topology based network construction using filter technique have been proposed. The DHT based technique is suitable for topic based pub/sub service but it's not good contents based service that has the variable requirements. And also filter based tree topology networking is not efficient at the environment where the user requirements are distributed. In this paper we propose the R-Tree algorithm based pub/sub overlay network construction method. The proposed scheme provides cost effective event delivery method by mapping user requirement to multi-dimension and hierarchical grouping of the requirements. It is verified by simulation at the variable environment of user requirements and events.