• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
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• pp.255-257
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• 2004

The study for ubiquitous computing infra is proceeding actively, it make possible to use service and access network anywhere, anytime because of wire/wireless communication technology and progress of hardware. Domestically, study for the network mobility support technology which is the key technology for future ubiquitous computing realization have progressed, but that is insufficient. Especially, there is no study for independent mobility support study about railway wireless network. So, this study propose network mobility management technology for mobile network infra in railway and proper network model in train.

• Journal of Information Processing Systems
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• 제14권3호
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• pp.771-789
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• 2018

In heterogeneous wireless networks supporting multi-access services, selecting the best network from among the possible heterogeneous connections and providing seamless service during handover for a higher Quality of Services (QoSs) is a big challenge. Thus, we need an intelligent vertical handover (VHO) decision using suitable network parameters. In the conventional VHOs, various network parameters (i.e., signal strength, bandwidth, dropping probability, monetary cost of service, and power consumption) have been used to measure network status and select the preferred network. Because of various parameter features defined in each wireless/mobile network, the parameter conversion between different networks is required for a handover decision. Therefore, the handover process is highly complex and the selection of parameters is always an issue. In this paper, we present how to maximize network utilization as more than one target network exists during VHO. Also, we show how network parameters can be imbedded into IEEE 802.21-based signaling procedures to provide seamless connectivity during a handover. The network simulation showed that QoS-effective target network selection could be achieved by choosing the suitable parameters from Layers 1 and 2 in each candidate network.

• 전기학회논문지
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• 제64권10호
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• pp.1448-1453
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• 2015

In this paper, we propose an alternative method of communication to improve the reliability of in-vehicle networks by jointly using wireless communication networks. Wired Communication networks have been used in vehicles for the monitoring and the control of vehicle motion, however, the disconnection of wires or hardware fault of networks may cause a critical problem in vehicles. If the network manager detects a disconnection or faults in wired in-vehicle network like the Controller Area Network(CAN), it can redirect the communication path from the wired to the wireless communication like the Zigbee network. To show the validity and the effectiveness of the proposed in-vehicle network architecture, we implement the Electronic Stability Control(ESC) system as ECU-In-the-Loop Simulation(EILS) and verify that the control performance can be kept well even if some hardware faults like disconnection of wires occur.

• 전기학회논문지
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• 제57권6호
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• pp.1063-1068
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• 2008

BACnet(Building Automation and Control Networks) is a standard data communication protocol specifically designed for building automation and control systems, BACnet provides six options for data link layer protocols and these six data link layer options can be applied with various wired transmission media. Recently wireless technology prevails in automation area. ZigBee is an IEEE 802.15.4 based standard communication protocol for low-rate wireless personal area networks. In this study, we propose a BACnet over ZigBee model that adopts ZigBee communication channel as a wireless data link layer protocol in a BACnet-based communication network system. The technology proposed in this paper can expand the BACnet application using the advantages of wired and wireless integrated network solution.

• International Journal of Internet, Broadcasting and Communication
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• 제13권3호
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• pp.25-33
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• 2021

Energy-harvesting wireless sensor networks(EH-WSNs) can collect energy from the environment and overcome the technical limitations of existing power. Since the transmission distance in a wireless sensor network is limited, the data are delivered to the destination node through multi-hop routing. In EH-WSNs, the routing protocol should consider the power situations of nodes, which is determined by the remaining power and energy-harvesting rate. In addition, in applications such as environmental monitoring, when there are urgent data, the routing protocol should be able to transmit it stably and quickly. This paper proposes an adaptive routing protocol that satisfies different requirements of normal and urgent data. To extend network lifetime, the proposed routing protocol reduces power imbalance for normal data and also minimizes transmission latency by controlling the transmission power for urgent data. Simulation results show that the proposed adaptive routing can improve network lifetime by mitigating the power imbalance and greatly reduce the transmission delay of urgent data.

• 한국철도학회논문집
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• 제16권6호
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• pp.551-557
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• 2013

본 연구는 철도전용 통합무선망 개발을 위한 LTE 통신 방식의 적용타당성 연구를 목적으로 하며, 호남선 일로역에서 대불역 사이 약 12km 구간에 걸쳐 철도전용 통합무선망을 구축하여 실증 분석하였다. 한국의 철도 안전 무선통신은 노선 별로 방식이 상이하여 각 철도 종사자간 협업이 어려워 다양한 문제점이 발생하고 있으며 무선통신 시스템간 통화 단절 및 상용 무선망과의 주파수 간섭 및 혼신에 따른 사고 발생 위험이 상존하고 있다. 본 연구는 이러한 문제를 해결하기 위한 방법으로 대두되고 있는 철도전용 통합무선망에 4세대 통신방식인 LTE를 적용하는 것이 타당한지를 살펴보았다. 열차 선로라는 기지국 설치 위치의 제약이 있었음에도 모든 시험 항목에서 기존 유럽의 GSM-R의 성능 기준을 상회하는 결과를 보였다.

• 한국인터넷방송통신학회논문지
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• 제11권3호
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• pp.99-105
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• 2011

일반적으로 재난 상황에서는 신속하고 쉽게 전개될 수 있는 확실한 재난관리통신이 요구되지만, 다층구조 건물 또는 넓게 펼쳐진 창고 시설은 신뢰할 만한 통신환경을 어렵게 한다. 이러한 재난 환경에서 휴대형 무선 메쉬 네트워크 기술은 소출력으로도 넓은 서비스 커버리지 확보가 가능하며, 유연성 있는 장비의 설치 및 재배치를 통한 네트워크 노드 당 경제성이 높은 기술이다. 본 연구에서는 네트워크 프로세스를 사용하여 재난 통신망 구축에 활용 될 수 있는 휴대형 무선 메쉬 네트워크 게이트웨이를 개발하고 기본적인 연결 기능과 더불어 스루풋과 지연, 패킷 손실 등의 성능을 시험하였다. 시험 결과는 재난 구조 통신망과 같은 다양한 환경에서 사용할 수 있는 기본적인 성능을 갖고 있음을 보여주었다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.2787-2794
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• 2011

A mesh node, a component of a mesh network, is connected with the network by dynamic routing using routing protocol and collects the information of adjacent or connected mesh nodes for its self-management and settings. Also, it relays packets between the mesh nodes and provides AP(Access Point) with its corresponding functions based on IEEE 802.11 a/b/g for clients' access to the network. In this paper, the study focused on the design and performance tests of Wireless Mesh Network(WMN) which is applied to the wireless communication network for the CBTC(Communications Based Train Control) system. The WMN was established on a K-AGT test-line (Kyeongsan city, Gyeongsangbuk-do), and to verify the applicability, its operation and performances are checked by measuring the data throughput, delay latency, quality measurements such as transmission loss, radio interference and path recovery and setup between the on-board and wayside.

• Journal of Information Processing Systems
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• 제13권1호
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• pp.141-151
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• 2017

Effective identification of wireless channel in different scenarios or regions can solve the problems of multipath interference in process of wireless communication. In this paper, different characteristics of wireless channel are extracted based on the arrival time and received signal strength, such as the number of multipath, time delay and delay spread, to establish the feature vector set of wireless channel which is used to train backpropagation (BP) neural network to identify different wireless channels. Experimental results show that the proposed algorithm can accurately identify different wireless channels, and the accuracy can reach 97.59%.

• 제어로봇시스템학회논문지
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• 제6권8호
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• pp.652-658
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• 2000

Wired and wireless communication technique is growing rapidly. As the number of communication users is larger problems such as network congestion and signal interference between users are getting most important, There have been researches that try to solve them by control theoretic approaches. They apply various control theories to the control issues of communication. this paper surveys these researches and classifies them into ATM TCP/IP and wireless communication according to the target. The feedback control model of each communication protocol is shown and related researches are summarized and analyzed.