• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.8
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• pp.1-10
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• 1995

We have analyzed the reliability of failure models in circuit-switched networks. These models are grid topology circuit-switched networks, and each node transmits a packet to a destination node using a Flooding routing method. We have assumed that the failure of each link and node is independent. We have considered two method to analyze reliability in these models : The Karnaugh Map method and joint probability method. In this two method, we have analyzed the reliability in a small grid topology circuit switched network by a joint probability method, and comared analytic results with simulated ones. For a large grid enormous. So, we have evaluated the reliability of the network by computer simulation techniques. As results, we have found that the analytic results are very close to simulated ones in a small grid topology circuit switched network. And, we have found that network reliability decreases exponentially, according to increment of link or node failure, and network reliability is almost linearly decreased according to increment of the number of links, by which call has passed. Finally, we have found an interesting result that nodes in a center of the network are superior to the other nodes from the reliability point of view.

• The Transactions of the Korea Information Processing Society
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• v.1 no.3
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• pp.327-338
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• 1994

In this paper, we propose a time relation model among media with the concept of time and space under hypermedia environments. The model explains time relations of node proceedings among media by time and proceedings among media connected with link. Using this model, hypermedia system which constructs dynamic nodes with time proceeding is designed and implemented. And this hypermedia system provides editing tool and controllers to edit dynamic node information, link tool to construct associative relations among nodes and navigaton tool to do node movement freely, various time controls and node proceedings.

• Journal of Applied Reliability
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• v.14 no.2
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• pp.103-107
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• 2014

An algorithm to get network reliability, where each link has probability of fuzzy number, is proposed. Decomposition method and fuzzy numbers arithmetic are applied to the algorithm. Pivot link is chosen one by one from start node recursively at time of decomposition, and arithmetic of fuzzy complementary numbers is included at the same time. No criteria of pivot link selection and the recursive calculation make the algorithm simple.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.7
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• pp.837-844
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• 2015

A research of Social Network is focused to the single node and link. But when we consider the complexity of Social Network, I think we need the analysis of integrated influence by multiple nodes that satisfied with specific condition. But, the study of this area don't process apart from Sub-network concept. The purpose of this paper is to focus on the analysis of influence by multiple nodes. For it, I define a new term as Group Node, and it express multiple nodes that satisfied a specific condition. And I propose a method for reconstruction by using Group Node in Social Network. and I make a program that produce a Group Node satisfied with a special condition by using Genetic Algorithm, and show the result. I hope this result can be a start point of the Social Network analysis based on Group Node.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.9
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• pp.4023-4043
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• 2016

Network virtualization has been regarded as a core attribute of the Future Internet. In a network virtualization environment (NVE), multiple heterogeneous virtual networks can coexist on a shared substrate network. Thus, a substrate network failure may affect multiple virtual networks. In this case, it is increasingly critical to provide survivability for the virtual networks against the substrate network failures. Previous research focused on mechanisms that ensure the resilience of the virtual network. However, the resource efficiency is still important to make the mapping scheme practical. In this paper, we study the survivable virtual network embedding mechanisms against substrate link and node failure from the perspective of improving the resource efficiency. For substrate link survivability, we propose a load-balancing and re-configuration strategy to improve the acceptance ratio and bandwidth utilization ratio. For substrate node survivability, we develop a minimum cost heuristic based on a divided network model and a backup resource cost model, which can both satisfy the location constraints of virtual node and increase the sharing degree of the backup resources. Simulations are conducted to evaluate the performance of the solutions. The proposed load balancing and re-configuration strategy for substrate link survivability outperforms other approaches in terms of acceptance ratio and bandwidth utilization ratio. And the proposed minimum cost heuristic for substrate node survivability gets a good performance in term of acceptance ratio.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.7
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• pp.1412-1418
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• 2005

Recently, more and more portable terminals probably have multiple interfaces to be connected to different access technologies. Each technology has its specific characteristics in terms of coverage area, bandwidth, reliability, etc. For example, the mobile node is equipped with three heterogeneous interfaces; IEEE 802.1lb MLAM link, CDMA Cellular link, and 802.16 WiMAX link These mobile nodes may be reachable through different links at the same time or use each interface alternately depending on the network environment. As like this, the portable terminal equipped multiple interfaces can have many benefits; it should be connect to Internet through other interface in case of occurring to failure for currently activate interface, and it should share a mount of traffic efficiently per interface etc. This environment is called end node Multihoming. However, current most Internet protocols are designed originally with single interface in mind. So these potocols do not provide methods for supporting simultaneous diffentiated use of multiple access technologies. In this paper, firstly we have to refer technical consideration items to use multiple interfaces based on IPv6 simultaneously. And we should propose extended registration mechanism for multiple addresses being acquired from interfaces to support reliable accessibility and vertical handover.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.12B
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• pp.1075-1082
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• 2008

A greedy forwarding algorithm is one of the most suitable solutions for routing in vehicular ad-hoc networks. Compared to conventional routing protocols for mobile ad-hoc networks, greedy forwarding based routing protocols maintain only local information of neighbors instead of per-destination routing entries, and thus they show better performance in highly-mobile vehicular ad-hoc networks. With greedy forwarding, each node learns its geographical position and periodically broadcasts a beacon message including its position information. Based on the position information, each node selects a neighbor node located closest to the destination node as the next forwarder. One of the most serious problems in greedy forwarding is the lost link problem due to the mobility of nodes. In this paper, we propose a new algorithm to reduce the lost link problem. The proposed algorithm aims to find an efficient and stable routing path by taking account of the position of neighbors and the last beacon reception time. Our simulation results show that the proposed algorithm outperforms the legacy greedy algorithm and its variants.

• Journal of KIISE:Computer Systems and Theory
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• v.26 no.10
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• pp.1248-1257
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• 1999

MDDS는 디스크 시스템의 성능을 향상시키기 위해 하이퍼큐브의 각 노드에 디스크 블록들을 분산 저장하며, 인접한 노드에서 분산 저장하고 있는 디스크 블록을 중복 저장하고 있는 디스크 시스템이다. 본 논문에서는 디스크 서비스 시간을 분석하기 위한 선행 연구로서 소스 노드에서 생성된 디스크 서비스 요구 메시지가 디스크 서비스를 제공하는 목적 노드에 수신될 때까지의 시간인 전송 시간을 분석한다. 이러한 메시지의 전송 시간을 분석하기 위해 이 메시지가 링크를 통해 전송되지 못하고 대기할 확률인 전송 대기 확률을 분석한다. 이들 메시지의 전송 대기 확률을 분석하기 위해 메시지가 각 링크에서 전송되지 못하고 대기해야 하는 시간인 전송 대기 시간을 분석한다. 또 디스크 서비스 요구 메시지의 전송을 위해 링크가 사용되는 비를 분석하며, 메시지의 전송 대기 확률, 전송 대기 시간, 메시지 전송을 위해 링크가 사용될 비를 이용하여 디스크 서비스 요구 메시지의 전송 시간을 분석한다. Abstract Mirrored Declustering Disk System(MDDS) is the disk system to enhance the performance of disk system for hypercube. In MDDS, each node stores the disk blocks using the declustering technique. And the node also duplicates the disk blocks stored in neighboring nodes. In this paper, as the leading research for analyzing the disk service time, we analyze the transmission time of the disk service request message from the source node to the destination node. To analyze the transmission time of disk service request message, we analyze the probability of blocking the message related to the disk service request. For the analysis of the blocking probability, we analyze the blocking time at the link. We also analyze the rate at which the transmission link is used for transferring the disk service requests. And we analyze the transmission time of disk service request message by using the blocking probability, the blocking time, and the usage rate of link for transmitting the message.

• Proceedings of the Korea Society of Design Studies Conference
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• 2002.05b
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• pp.154-155
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• 2002

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.412-415
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• 1999

In this paper, we describe an implementation of the B-Link bus interface logic for a directory controller and a remote access cash controller in the SCI-based CC-NUMA multimedia server developed by ETRI . The CC-NUMA multimedia server is composed of a number of Pentium III SHV nodes and a SCI interconnection network. To communicate with remote nodes, each node has a CC-Agent which consists of a processor bus interface(PIF). a directory controller(DC), a remote access cash controller(RC), and two SCI 1ink controllers(LCs). The B-Link bus interface logic is developed for a directory controller and a remote access cash controller in order to communicate with a SCI link controller on a B-Link bus. It consists of a sending master controller a receiving slave controller, and asynchronous data buffers. And It performs a self-arbitration, a data packet transmission, a queue allocation, an early terminal ion. and a cut-through data path.