• Journal of Communications and Networks
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• v.12 no.3
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• pp.246-252
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• 2010

A binary linear integer program is formulated for the problem of expanding the capacity of a fiber optic network and routing the traffic to deliver new interactive multimedia services. A two-phase Lagrangian dual search procedure and a Lagrangian heuristic are developed. Computational results show superior performance of the two-phase subgradient optimization compared with the conventional one-phase approach.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.4
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• pp.1969-1975
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• 2013

ICN (Information-Centric Network) is a next generation Internet communication technology for converting existing Internet communication paradigm to information-based communication paradigm to efficiently use a large amount of information that exists on the Internet. Therefore, unlike existing Internet communication technologies focused on the process of communication using the host address, ICN focuses on the purpose of communication for each information by defining the information of everything that exists on the Internet. For this purpose, ICN uses NbR (Name-based Routing) methods that assign a name to each piece of information, all routers participating in ICN have the physical storage so that they are able to share information with each other. NbR methods on ICN are divided into one-phase routing and two-phase routing depending on how to reach at the storage of each router. However, currently proposed NbR methods cause many problems because they do not reflect the unique characteristics of ICN. Therefore, this paper looked at various NbR issues from caching, access time, distribution, mobility, scaliability, and dissemination of information for an efficient NbR method, and analyzed existing methods proposed for ICN. This paper also proposed a research direction to study the efficient NbR for ICN based on the analysis information.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.12B
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• pp.1066-1080
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• 2003

In this paper a scalable QoS routing scheme for distributed multimedia applications in a hierarchical wide area network is proposed. The problem of QoS routing is formulated as a multicriteria shortest path problem, known as NP-complete. The proposed hierarchical routing scheme consists of two phases. In Phase 1, every border node periodically pre-computes the QoS distance for the paths between every pair of border nodes in any level of domain hierarchy. This phase is independet of the QoS request from an application. In Phase II, distributed graph construction algorithm is performed to model the network as a graph by retrieving pre-computed QoS distances. The graph is constructed by the on-demand algorithm and contains a part of the network topology which is completely neglected or partially considered by existing routing schemes, thus maintaining more accurate topology information. By using retrieval approach rather than advertising one, no global QoS state information exchange among nodes is needed. In this Phase, distributed partition algorithm for QoS routing problem is also performed, thus eliminating virtual links on the hierarchically complete path.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.7B
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• pp.1239-1251
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• 1999

In this paper a scalable QoS-based hierarchical inter-domain routing scheme for distributed multimedia applications in a high speed wide area network. The problem of QoS-based routing is formulated as a multicriteria shortest path problem, known as NP-complete[21,30]. Our routing scheme consists of two phases. In Phase 1, two graph construction algorithms are performed to model the network under consideration as a graph. The graph contains a part of the network topology which is completely neglected or partially considered by existing routing schemes, thus maintaining more accurate topology information. In Phase 2, a heuristic call-by-call algorithm is performed for selecting a feasible path efficiently in depth first search-like manner on the graph and tailoring to each application's QoS requirements, beginning at a vertex that represents the source node. In this paper, a simple rule is also produced, by which the visiting order of outgoing edges at each vertex on the graph is determined. The rule is based on each edge's the minimum normalized slackness to the QoS requested. The proposed routing scheme extends the PNNI-type hierarchical routing framework. Note that our routing scheme is one of a few QoS-based hierarchical routing schemes that address explicitly the issue of selecting a path with multiple metrics.

• Magazine of the Korean Society of Agricultural Engineers
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• v.36 no.3
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• pp.60-66
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• 1994

This paper is to validate the proposed models for the real-time forecasting for the Keum river estuary dam such as tidal-level forecasting model, one-dimensional unsteady flood routing model, and Kalman filter models. The tidal-level forecasting model was based on semi-range and phase lag of four tidal constituents. The dynamic wave routing model was based on an implicit finite difference solution of the complete one-dimensional St. Venant equations of unsteady flow. The Kalman filter model was composed of a processing equation and adaptive filtering algorithm. The processng equations are second ordpr autoregressive model and autoregressive moving average model. Simulated results of the models were compared with field data and were reviewed.

• Magazine of the Korean Society of Agricultural Engineers
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• v.36 no.3
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• pp.67-73
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• 1994

This paper is to validate the proposed models for the real-time forecasting for the Keum river estuary dam such as tidal-level forecasting model, one-dimensional unsteady flood routing model, and Kalman filter models. The tidal-level forecasting model was based on semi-range and phase lag of four tidal constituents. The dynamic wave routing model was based on an implicit finite difference solution of the complete one-dimensional St. Venant equations of unsteady flow. The Kalman filter model was composed of a processing equation and adaptive filtering algorithm. The processng equations are second ordpr autoregressive model and autoregressive moving average model. Simulated results of the models were compared with field data and were reviewed.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.17 no.4
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• pp.21-35
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• 2007

In ad hoc networks, position-based routing schemes, that use geographical positions of nodes, have been proposed to efficiently route messages. In these routing schemes, the location service is one of the key elements that determines and effects security and efficiency of the protocol. In this paper, we define security threats of location service and propose a new quorum based location service protocol. In our proposed protocol, nodes register their public keys in other nodes during the initialization phase and these registered keys are used to verify locations of other nodes and the messages exchanged. In this paper, we prove that our protocol is robust against traditional attacks and new attacks that may occur due to the use of position-based routing. We also analyze the efficiency of our protocol using various simulations.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.17 no.5
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• pp.15-25
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• 2007

According to augmentation about interesting and demanding of privacy over the rest few years, researches that provide anonymity have been conducted in a number of applications. The ad hoc routing with providing anonymity protects privacy of nodes and also restricts collecting network information to malicious one. Until recently, quite a number of anonymous routing protocols have been proposed, many of them, however, do not make allowance for authentication. Thus, they should be able to have vulnerabilities which are not only modifying packet data illegally but also DoS(denial of service) attack. In this paper, we propose routing protocol with providing both anonymity and authentication in the mobile ad hoc network such as MANET, VANET, and more. This scheme supports all of the anonymity properties which should be provided in Ad Hoc network. In addition, based on the group signature, authentication is also provided for nodes and packets during route discovery phase. Finally, route discovery includes key-agreement between source and destination in order to transfer data securely.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2002.05a
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• pp.120-127
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• 2002

The multicasting is defined as the distribution of the same information stream from one to many nodes concurrently. There has been an intensive research effort to design protocols and construct multicast routing graphs for a single multicast group. However. there have been few researches about the relation between multiple and concurrent multicast groups. In this paper, the multiple multicast tree allocation algorithm to avoid congestion is proposed. The multicast group with different bandwidth requirement is also considered. A two-phase algorithm is proposed. The first phase is for basic search and the second phase for further improvement. The performance of the proposed algorithm is experimented with computational results. Computational results show that the proposed algorithm outperforms an existing algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.8A
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• pp.810-819
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• 2010

This paper proposes an algorithm to improve total network lifetime for Wireless Sensor Network (WSN) application such as environmental condition monitoring systems based on LEACH protocol. Firstly, the algorithm had equal number of nodes allocated to each cluster at cluster set-up phase where it abided by LEACH protocol. Secondly, at cluster set-up phase, each node was determined the order to be cluster header of the cluster which it had joined. After then, the role of a cluster head delivers to the next node according to determined order when the cluster head has received certain number of packets. With above method energy consumption of each node made equal and overall network lifetime was increased. Simulation results shows that overall network lifetime of proposed algorithm was increased two times than that of LEACH and total energy consumption was one forth of that of LEACH protocol.