• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.2
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• pp.1-5
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• 2007

Wavelength-division multiplexed (WDM) networks are emerging to be the right choice for the future transport networks. In WDM networks, the optical layer provides circuit-switched lightpath services to the client layer such as IP, SONET and ATM. The set of lightpaths in the optical layer defines the virtual topology. Since the optical switches are reconfigurable, the virtual topology can be reconfigured in accordance with the changing traffic demand pattern at theclient layer in order to optimize the network performance. We present a new approach to the virtual topology reconfiguration and loadbalancing problem for wavelength-routed, optical wide-area networks under dynamic traffic demand. By utilizing the measured Internet backbone traffic characteristics, our approach follows the changes in traffic without assuming that the future traffic pattern is known. For the simulation traffic modeling, we collected the data from real backbone traffic. Experiments show that the standard deviation compared to previous technique is reduced.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.10
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• pp.21-29
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• 2015

For higher reliability against component failures in railroad trains with many electronic sensors and actuators, a distributed control system with which all electronic components are connected via a network is being considered. This paper compares and analyzes various topologies of Ethernet network for a railroad train in the aspects of (1) failure recovery, (2) the number of ports per device, (3) the number of cable connections between vehicles, and (4) performance. Especially, the unique characteristic of a train system that the number of vehicles changes is considered through analysis. Various combinations of in- and inter-vehicle topologies are considered. In addition, we introduce a hybrid of star and daisy-chain topology for inter-vehicle connection when the maximum number of inter-vehicle connections is limited to reduce possible failures of inter-vehicle connections. Simulation results show performance comparison between different topology combinations; the hybrid topology is shown to enhance delay performance even with a highly limited number of inter-vehicle connections.

• Journal of Korea Multimedia Society
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• v.16 no.4
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• pp.472-482
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• 2013

This paper proposes a wireless LAN topology configuration method for enhancing indoor location-awareness and improving network performance simultaneously. We first develop four objective functions that yield objective goals significant to the optimal design of a wireless LAN topology in terms of location-awareness accuracy and network performance factors. Then, we develop metaheuristic algorithms such as simulated annealing, tabu search, and genetic algorithm that examine the proposed objective functions and generate a near-optimal solution for a given objective function. Finally, four objective functions and metaheuristic algorithms developed in this paper are exploited to evaluate and measure the performance of the proposed wireless LAN topology configuration method.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.9
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• pp.917-922
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• 2016

There are many researches related on the brain wave signals to monitor the state of human health. Especially, some patients in the medical hospital need to be monitored in case of emergencies such as a seizure, an epilepsy and so on. To support QoS of the brain wave network in the hospital is a vital issue and the Opnet simulator is used for this experiment. So the efficient network topology is required for the stability of the brain wave network service. The brain waves of the patients are collected from the sensor devices in the network. Two different sensor network topologies are suggested and simulated for the comparison of the network performance. One topology is localized and the other is non-localized network. The simulation is operated with the Opnet simulator.

• 월간 기계설비
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• s.112
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• pp.76-80
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• 1999

네트워크는 어떤 공동의 목적을 위해 다수 지점간에 상호 연결된 통신형태를 말한다. 네트워크를 구현하고 표현하기 위한 방법은 여러가지가 있으나 대표적인 방법으로 프로토콜과 토폴로지를 들 수 있을 것이다. 프로토콜은 소프트웨어의 형태이며, 토폴로지는 하드웨어의 형태라고 할 수 있다. 이러한 것들의 집합을 네트워크 아키텍쳐(Network Architecture)라고 하는데, ISO(International Standard Organization)의 OSI(Open System Interconnection) 모델, IBM의 SNA(System Network Architecture)를 기준으로 사용자의 필요와 목적에 따라 다양한 형태로 표현되고 구현된 네트워크 아키텍쳐들이 있다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.5
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• pp.922-931
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• 2012

This paper studies a series of logical topology reconfiguration processes corresponding to a series of traffic demand changes in a ship backbone network. The proposed reconfiguration technique is to minimize costly changes of traffic forwarding paths and minimize the average hop distance of traffic forwarding paths in terms of ship backbone network performance simultaneously. Performance evaluation is conducted to illustrate the efficiency of the proposed reconfiguration technique. It shows that the proposed reconfiguration technique yields efficient performance in the entire series of reconfiguration processes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.6A
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• pp.802-812
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• 2000

Multihop lightwave networks are the optical-fiber based local communication systems that employ WDM(Wavelength Division Multiplexing) technology to fully use the enormous fiber bandwidth without requiring any tunable tranceives. In this paper, we introduce a novel ShuffleNet topology, asymmetric bilayered ShuffleNet(ABS) topology as a multihop WDM network technique. For 1Gb/s transmission system, we compared ABS topology with previously reported ones in terms of common network parameters such as average number of hops, throughput, time delay, and network power function. Through the analysis, the performance of ABS topology was proven to be superior to the existing ones. To decrease the amount of hardware required for implementing ABS system, we also proposed a new WDM channel sharing scheme. For (2, 3) ShuffleNet topology system, the number of wavelengths needed in the system can be reduced dramatically from 96 to 4 by using new scheme.

• 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.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.7B
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• pp.510-517
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• 2008

In wireless sensor networks, a number of nodes deployed in dense manner should be self-configured to establish a topology that provides communication and sensing coverage under stringent energy constraints. To establish an efficient topology, we propose the TRaffic-Aware Topology control (TRAT) algorithm that reduces energy dissipation by considering total amount of data flows in the network. Our algorithm controls the number of active nodes with traffic information and adjusts nodal transmission power by estimating amount of data flows. According to the result, the proposed algorithm shows about 30% better performance than the other methods in terms of energy efficiency.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.6
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• pp.1207-1213
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• 2009

A design method of network Topology for Integrated Management of various Networks is prposed and an example is shown. The TMN-DCN devices are assigned for each of the various networks. These devices have functions of network management. Also we propose the simple design methods of the network topology with survivability as one of the network management elements. The design methods are very simple but very useful. Because there is no general design algorithm for optimal topology with network survivability.