• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.3
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• pp.29-38
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• 1998

This ppaer suggests a congestion control scheme for CL(ConnectionLess) overlay network using the feedback loops getween CL werver, between CL servers, and the header translation table of CL server. The CL overlay network for CBDS(Connectionless Broadband Data Service) defined by ITU0T(International Telecommunication Union-Telecommunication) consists of CL servers which route frames and links which connect between CL user and CL server or between CL servers. In this CL overlay network, two kinds of congestions, link congestion and CL server congestion, may occur. We suggest a scheme that can solve the congestion using ABR(Available Bit Rate) feedback control loop, the traffic control mechanism. This scheme is the link-by-link method suing the ABR feedback control loops between CL user and CL server or between CL servers, and the header translation table of CL server. As CL servers are always endpoints of ABR connections, the congestion staturs of the CL server can be informed to the traffic sources using RM(Resource Management) cell of the ABR feedback loops. Also CL server knows the trafffic sources making congestion by inspecting the source address field of CLNAP-PDUs(ConnectionLess Network Access Protocol - Protocol Data Units). Therefore this scheme can be implemeted easily using only both ABR feedback control loop of ATM layer and the congestion state table using the header translation table of CL server because it does not require separate feedback links for congestion control of CL servers.

• Journal of KIISE:Information Networking
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• v.31 no.4
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• pp.384-392
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• 2004

Mobile contents service providers have some difficulties to timely and proper service deployment due to rapid development cycle of diverse portable devices with different capabilities. A way to resolve the problem is to introduce a mobile contents service paltform that can adapt original mobile contents to diverse devices dynamically and automatically. In this paper, we propose a mobile contents service platform based on active network mechanisms, called Mobile Content Adaptation Network(MobiCAN). The MobiCAN node provides effective service deployment, execution, and maintenance features and accommodates service layering and service customization capabilities for easy deployment. The basic functional units of the MobiCAN node are micro services with well-defined service interfaces and service layering features. For reliable services among the MobiCAN nodes, we design new distributed and robust Overlay Management Protocols(OMPs). As an example of practical MobiCAN applications, we finally describe Dynamic Contents Customization Proxy(DCCP) service.

• Journal of the Korea Society of Computer and Information
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• v.26 no.6
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• pp.9-17
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• 2021

In this paper, we propose a reversely using the "Man In The Middle Attack" attack technique as a way to introduce network security without changing the physical structure and configuration of the existing network, a Virtual Network Overlay is formed with only a single Ethernet Interface. Implementing In-line mode to protect the network from external attacks, we propose an integrated control method through a micro network security sensor and cloud service. As a result of the experiment, it was possible to implement a logical In-line mode by forming a Virtual Network Overlay with only a single Ethernet Interface, and to implement Network IDS/IPS, Anti-Virus, Network Access Control, Firewall, etc.,. It was possible to perform integrated monitor and control in the service. The proposed system in this paper is helpful for small and medium-sized enterprises that expect high-performance network security at low cost, and can provide a network security environment with safety and reliability in the field of IoT and embedded systems.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.7
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• pp.1447-1454
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• 2012

Recently P2P is the most popular network service on Internet and is applied various areas such as streaming, file sharing and software distribution, but there are many security threats depending on vulnerabilities by P2P network environments. Conceptually P2P network is a overlay network based on Internet, and it has security concerns of itself as well as those of Internet environments. In this paper, we analyze the vulnerabilities and threats for domestic P2P services through various experiments and describe their risk analysis. We expect that this work contributes to new domestic P2P services in consideration of service qualities and security vulnerabilities.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.2B
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• pp.313-324
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• 2010

IPTV has been launched to provide a simple convergence service with broadcast and communication, and now it is evolving to support personalized service capabilities according to user's requirements. The paper presents DSON architecture and its control model to provide personalized features and user centric capability in IPTV services over service overlay network. Furthermore, the paper introduces DSON based service models on community IPTV and home IPTV service model.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.12
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• pp.1141-1153
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• 2010

This paper introduces ONLIS(Overlay Multicast Network for Live IPTV Service), a novel overlay multicast network optimized to deliver live broadcast IPTV stream. We analyzed IPTV reference model of ITU-T IPTV standardization group in terms of network and stream delivery from the source networks to the customer networks. Based on the analysis, we divide IPTV reference model into 3 networks; source network, core network and access network, ION(Infrastructure-based Overlay Multicast Network) is employed for the source and core networks and PON(P2P-based Overlay Multicast Network) is applied to the access networks. ION provides an efficient, reliable and stable stream distribution with very negligible delay while PON provides bandwidth efficient and cost effective streaming with a little tolerable delay. The most important challenge in live P2P streaming is to reduce end-to-end delay without sacrificing stream quality. Actually, there is always a trade-off between delay & stream quality in conventional live P2P streaming system. To solve this problem, we propose two approaches. Firstly, we propose DSPT(Distributed Streaming P2P Tree) which takes advantage of combinational overlay multicasting. In DSPT, a peer doesn't fully rely on SP(Supplying Peer) to get the live stream, but it cooperates with its local ANR(Access Network Relay) to reduce delay and improve stream quality. When RP detects bandwidth drop in SP, it immediately switches the connection from SP to ANR and continues to receive stream without any packet loss. DSPT uses distributed P2P streaming technique to let the peer share the stream to the extent of its available bandwidth. This means, if RP can't receive the whole stream from SP due to lack of SP's uploading bandwidth, then it receives only partial stream from SP and the rest from the ANR. The proposed distributed P2P streaming improves P2P networking efficiency.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.4B
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• pp.305-313
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• 2011

This paper presents a P2P (Peer-to-Peer) overlay multicast tree construction algorithm to support stable multimedia service over the Internet. While constructing a multicast tree, it takes into account not only the link delay, but also peer stability. Since peers actually show dynamic and unstable behavior over P2P-based network, it is essential to consider peer stability. Furthermore, the weighting factor between link delay and peer stability is adaptively controlled according to the characteristics of the multicast tree. Basically, Genetic algorithm is employed to obtain a near optimal solution with low computational complexity. Finally, simulation results are provided to show the performance of the proposed algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.12B
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• pp.1058-1065
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• 2008

In the Internet, as computer resource is developed, multimedia data request being increase more and more. It is effective way that process both high capacity-data and real-time data. Overlay Multicast is an effective method for efficient utilization of system resources and network bandwidth without using hardware customization. Overlay Multicast is an effective method for multimedia data service to multi-users. Multicast tree reconstruction is required when a non-leaf host leaves or fails. In this paper, relay-frame interval is selected as revealed network-state with jitter. In our proposal, multi-user service control algorithm gives a delay effect in multimedia request time. The simulation results show that our proposal takes shorter period of time than the other algorithms to reconstruct a similar tree and that it is a more effective way to deal with a lot of nodes that have lost their multi-user nodes.

• 한국HCI학회:학술대회논문집
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• 2009.02a
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• pp.232-239
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• 2009

Emerging social networking services provide a new paradigm for human-to-human communication. However, these services are centralized and managed by single service provider. In this paper, we propose MicroPost, a decentralized event notification service architecture for social applications based on publish/subscribe model. In our design space, event brokers are structured as an overlay network which provides the substrate of distributed peer-to-peer lookup service for storing and retrieving subscriptions with hashed keys. Event clients interact with event brokers to publish or subscribe social messages over the wide-area network. Using XML standards, we present an efficient algorithm to forward events for rendezvous-based matching in this paper. In our design space, the cost of routing is O(${\omega}log_kN$), where N is the number of event brokers, ${\omega}$ is the number of meta-data obtained from event messages, and k is a constant, which is selected by our design, to divide the identifier space and to conquer the lookup of given key. Consequently, what we achieved is an asynchronous social messaging service architecture which is decentralized, efficient, scalable, and flexible.

• The Journal of the Korea Contents Association
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• v.9 no.12
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• pp.528-536
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• 2009

Recently, the importance of IPTV providing multimedia service over IP based networks managed to provide the required level of quality of service and experience, security, interactivity and reliability has been gradually increasing by the commercialization of its service. However, the original purposes of IPTV service - contents are produced and consumed anytime, anywhere, and over any device at the same time - have not been satisfied by service providers because most services offered by service providers depend on closed IPTV platform. In this paper, we propose an open IPTV service platform that an individual or small company can easily produce contents and offer IPTV service independently from the existing closed IPTV platform.. The proposed IPTV platform exploits overlay multicast scheme to offer reasonable service under the environment where network bandwidth and processor resource are limited. It also uses CDN-like scheme to ensure the quality of transmitted contents. The performance evaluation shows that the proposed IPTV platform has the possibility of being an open IPTV platform considering its results such as the quality of transmitted contents, the transmission rate, the channel zapping time, and so on. It also shows that proposed IPTV platform could be applied to real IPTV service with continuous enhancement of its functions and user interfaces.