• The KIPS Transactions:PartA
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• v.14A no.6
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• pp.333-340
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• 2007

In multi agent systems, various inter agent communication models have been proposed, and, especially, there are several group communication schemes proposed so far, where some schemes guarantees transparent communication among the agents. However, in mobile agent environments, we require new group communication schemes that consider topology changes caused by mobile agent migrations. Also, these group communication schemes should be secure in order for them to be practical. In this paper, we propose a secure group communication scheme using the hierarchical overlay ring structure of mobile agents. The proposed scheme uses the ring channel in order to cope adaptively with the change of ring topology. The ring channel has basic information for construction of the ring and is managed only by the mobile agent platforms. Therefore, each mobile agent need not directly handle the ring channel and it can perform group communication without any consideration on the change of the ring topology.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06d
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• pp.348-350
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• 2012

광파장다중화(WDM) 기반 광인터넷 환경에서 논리적인 다중 링 구조에 의한 통신망 복구 기법을 연구한다. 이 방법은 링 토폴로지의 특성을 이용해 빠르고 간단한 복구 동작을 제공하며, 지역적인 복구를 수행한다. 동시에 다중 링 구성을 통하여 대체 경로의 분산과 공유 정도를 높이고 단위 링크당 예약되어야 하는 예비 광파장의 수를 줄임으로써 전체 통신망 자원 이용의 효율성을 높일 수 있다. 본 논문에서는 위험공유 링크그룹(SRLG) 개념을 이용하여 링크 손실을 복구하는데 필요한 예비대역폭 비율을 토폴로지상의 Cut-Set을 이용해 계산하고 이를 실험을 통해 확인하였다.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.5
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• pp.1-7
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• 2004

A regular logical topology requires little processing time for routing purposes which may be a desirable property for high-speed networks. Asymmetric bilayered ShuffleNet, proposed by us as a logical topology, can be used to a wavelength division multiplexing ring network to increase the network capacity compared to ShuffleNet. In this paper, asymmetric bilayered ShuffleNet is imbedded on a wavelength division multiplexing ring with the objective of minimizing the total number of wavelengths assigned.

• The Journal of Society for e-Business Studies
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• v.15 no.4
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• pp.49-58
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• 2010

The wireless sensor network technology becomes one of core technologies to make it possible to implement various e-business applications. Energy efficiency is an important issue in wireless sensor networks. IEEE 802.15.4, a representative international standard for wireless sensor networks, provides the beacon enabled mode for energy-efficient communication. However, the beacons may conflict each other when the network is of multi-hop topology such as mesh or cluster-tree topology with beacon-enabled mode. The beacon conflict causes the failure of synchronization between sensor nodes, and affects other nodes in the network in that unsynchronized nodes cannot participate in communication. In this paper, we suggest an energy-efficient beacon scheduling for the wireless sensor networks. Nodes can save their energy duringperiod and prevent beacon conflict using beacon scheduling. We implement the scheduling using QualNet, and evaluate the performance under mesh topology networks. It turns out that the proposed scheduling may improve the energy efficiency in the networks.

• Journal of Advanced Navigation Technology
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• v.11 no.4
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• pp.401-407
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• 2007

This paper proposes the ethernet-based in-vehicle networking method for "body" and "multimedia" domains. The ethernet-based in-vehicle networking method should modify the topology and the layer 2 for traffic shaping. In this paper, we simulate the two ring networking systems, the Media Oriented Systems Transport (MOST) and the proposed system with the shaping by the network simulator 2 and evaluate each performance. In addition, we demonstrate the proposed networking system to exchange two kinds of traffic, i.e., QoS data and best-effort data, on the ring network constituting of three nodes. Finally this paper expects to substitute the ethernet-based in-vehicle network for the MOST in advance.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.10b
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• pp.1303-1306
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• 2001

이 논문에서는 네트워크 모니터링을 위해 기존의 기법들과는 달리 네트워크 토폴로지를 기반으로 한 접근 방법을 통해 보다 효율적으로 폴링 트래픽에 대한 오버헤드를 제어하는 동적 폴링 기법을 제시하였다. 제안된 기법에서는 폴링트래픽에 대한 오버헤드를 제어하기 위해 관리 도메인의 네트워크 토폴로지 정보를 이용한다. 네트워크 토폴로지 정보를 이용하여 폴링을 위한 노드 리스트에서 각 노드들 간의 연결 관계를 표현한다면 토폴로지 순서에 의해 빠르고 정확하게 실시간 네트워크 정보를 파악할 수 있다. 따라서 이러한 방법을 통해 기존의 제안된 기법들 보다 폴링 처리율을 높임으로써 보다 효율적인 동적 폴링 기법을 제안하였으며, 다른 기법들과의 비교를 통해 제안된 기법의 효율성을 증명하였다.

• Journal of Internet Computing and Services
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• v.2 no.5
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• pp.93-104
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• 2001

In this paper. we analyze networks in accordance with topology which consists of ATM-LAN in order to enhance performance in multimedia environment, We analyze job processing time of Email, FTP and Http server for variance of node in star, ring and mesh topology, We analyze a load factor of Email, FTP and Http server and variance of sending/receiving rate for various topology, We examined that the constituent networks in this paper can minimize load of server in any other topology.

• Proceedings of the KIEE Conference
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• 2006.07d
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• pp.2144-2145
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• 2006

무선 센서네트워크는 환경 모니터링과 같은 다양한 어플리케이션을 갖고 있는 향상된 기술이다. 이를 구성하는 각각의 노드들은 특정지역에 분산되어 네트워크를 구성해서 해당 지역의 이벤트나 정보를 주기적으로 사용자에게 전달한다. 이때 토폴로지 제어는 네트워크의 수명과 통신에 중요한 영향을 미치는 요인이다. 본 논문에서는 무선 센서 네트워크에서 클러스터 기반의 분산형 토폴로지 제어기법을 제안한다. 이 기법은 먼저 네트워크를 클러스터 기반의 계층적인 구조로 구성한 후, 각각의 클러스터 내에서 최소 신장트리 (Minimum Spanning Tree)를 이용하여 토폴로지 제어를 수행한다. 이를 통해 무선센서 네트워크는 에너지 효율적이며 분산된 토폴로지 제어를 수행할 수 있고, 결과적으로 네트워크의 수명을 연장할 수 있다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.4B
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• pp.455-463
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• 2004

In this paper, we deal with a ring-mesh network design problem arising from the deployment of WDM for the optical internet. The ring-mesh network consists of ring topology and full mesh topology for satisfying traffic demand while minimizing the cost of OAOMs and OXCs. The problem seeks to find an optimal clustering of traffic demands in the network such that the total number of node assignments is minimized, while satisfying ring capacity and node cardinality constraints. We formulate the problem as a mixed-integer programming model and prescribe a tabu search heuristic procedure Promising computational results within 3% optimality gap are obtained using the proposed method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.9
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• pp.1655-1665
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• 2017

Recently data centers are being constructed actively by many cloud service providers, enterprises, research institutes, etc. Generally, they are built on tree topology using ECMP data forwarding scheme for load balancing. In this paper, we examine data center network topologies like tree topology and fat-tree topology, and load balancing technologies like MLAG and ECMP. Then, we propose a scheduling algorithm to efficiently transmit particular files stored on the hosts in the data center to the destination node outside the data center, where fat-tree topology and OpenFlow protocol between infrastructure layer and control layer are used. We run performance analysis by numerical method, and compare the analysis results with those of ECMP. Through the performance comparison, we show the outperformance of the proposed algorithm in terms of throughput and file transfer completion time.