• Journal of the Korean Society for Railway
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• v.16 no.6
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• pp.460-465
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• 2013

Radio propagation in a high-speed railway is affected by ground reflective waves that are due to irregular reflection by the railway track, which consists of rails, sleepers, and gravel. This paper provides a train radio propagation model that simulates an irregular track reflective wave as a random variable. A simulation study using the train radio propagation model shows that the path loss exponent is around 3.0, indicating a reduced path loss compared to the value of 4.0 in the general mobile radio environment. Regressive analysis of the received signal strength indicators measured in the Gyeongbu high-speed railway showed the results identical to those of the simulation. These results confirm the train radio propagation model and can be applied to the coverage estimation and the design of a train radio network.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.4
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• pp.2355-2362
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• 2014

Electric railway induces interference voltage on wayside communication cable which brings about communication errors, malfunction of devices, and safety problem. The magnitude of the induced voltage depends on the electromagnetic field coupling which is affected by metallic installations such as rail and track structures. This paper provides an experimental analysis of the screening effect of metallic pipe on the inductive voltage caused on communication cable. The measurements at a high-speed rail site show that the screening effect of metallic pipe is about 20% when the separation distance between the pipe and communication cable is 1~2 m. The screening effects is less than 1% and can be neglected when the separation distance is more than 4 m. These results are useful to evaluate the screening effects of the metallic installations such as water pipe, gas pipe, and reinforcing bar.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.568-570
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• 2018

Currently, with rapid progress and supply of mobile communication technology, LTE(Long Term Evolution) technology is expanded and widely used to industrial and emergency communications beyond earlier smart-phone based service. In this paper, transmission performance of voice traffic, one of railway communication service based on LTE-R as an application field of LTE technology, is analyzed. This study is performed performance analysis with level of application service and consider effects of satisfaction level for users. Computer Simulation based on ns(Network Simulation)-3 is used for analysis and VoIP(Voice over Internet Protocol) specification is used for voice traffics. Results of this paper is used to implement LTE-R networks and develope application services over LTE-R network.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.10
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• pp.181-189
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• 2007

This paper presents a experimental evidence of the generation of the earth potential and communication line noise from the electric railway. There is a critical measurement err in case of measuring the electrical power induced noise voltage and degree of cable balance in the field of earth potential generated. As a results, it has been found that the conventional cable has more noise immunity than shielded cable near the railway where the earth current flows through the sheath layer.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.1248-1250
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• 2001

전기철도에서의 급전시스템은 레일을 귀선으로 사용하는 단상급전시스템을 사용하고 있다. 이에 따라 레일로부터 대지로의 누설에 의해 상당한 누설전류가 대지로 흐르게 된다. 대지로 흐르는 이 누설전류는 전자유도에 의해 선로 주변에 설치된 통신 케이블 또는 장치에 영향을 주게 된다. 더욱이 전기차의 견인시스템은 견인전동기를 제어하는데 있어서 스위칭 소자의 개폐에 의한 고조파 전류를 발생하고 있어 대지누설전류에 고조파 전류가 포함되어 흐른다. 본 연구에서는 전기철도 급전시스템에서 통신유도원인 대지누설전류에 따른 고려되어야 할 급전시스템 설계 파라미터를 시뮬레이션을 통하여 검증하였으며, 이 결과가 향후 급전시스템 설계시 기본적인 지침이 되어야 할 것이다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2019.05a
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• pp.456-458
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• 2019

In this paper, transmission performance of streaming audio as a railway communication service based on LTE-R is analyzed. Performance analysis is perfomed with computer simulation based on NS(Network Simulation)-3, audio frame of MPEG(Moving Picture Experts Group)-4 is used as target application service for straming audio traffic. Results of this paper can be used to implement LTE-R networks and develope application services over LTE-R network.

• Journal of Satellite, Information and Communications
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• v.2 no.2
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• pp.1-9
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• 2007

In this paper, we describe the performance degradation of satellite Wibro system and compensation method in the high-speed railroad channel environment. High-speed railroad channel environment is divided into LOS channel and tunnel. In the LOS channel, signal blocking caused by railroad power feeder structures can be a critical problem which is can be solved with antenna diversity. On the other hand, multi path interference phenomenon, representable by propagation model of Optic Fiber, occurred in the tunnel may be another obstacle. These satellite Wibro system performance degradations in railroad channel environment are addressed and adequate compensation methods are proposed and verified through computer simulation. In addition, the ICI caused by Doppler shift in OFDM system is analyzed with its compensation method.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.24 no.1
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• pp.163-174
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• 2024

Currently, the urban railway operating agency is improving the emergency telephone in operation into an IP-based "trackside integrated interface communication facility" that can support a variety of additional services in order to quickly respond to emergency situations within the tunnel. This study is based on this Analyze the needs of various stakeholders regarding the design of a system architecture that establishes an IoT sensor network environment to detect abnormal situations in the tunnel and transmits the collected information to the control center to predict disaster situations in advance, and defines the system requirements. In addition, a scenario model for disaster response was provided through the presentation of a service model. Through this, the perspective of responding to urban railway disasters changes from reactive response to proactive prevention, thereby ensuring safe operation of urban railways and preventing major industrial accidents.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1240-1241
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• 2011

이 논문은 LS전선, 서울 메트로, 철도기술연구원(KRRI)이 공동으로 연구한 '도시철도 연계 EV 충전 시스템' 프로젝트와 LS전선, 환경공단이 공동 개발한 '전기 자동차 충전 인프라 구축 사업'을 바탕으로 내용을 구성 하였다. 전기 자동차 충전 인프라 시스템 구축은 크게 3가지 이슈 -전력 연계, 충전 시설, 충전기 운영 통신 시스템-가 있다. 전기 자동차 충전 시스템을 철도 전력 인프라망을 연계했을 때 얻을 수 있는 이점들, 충전 인프라 운영 시스템에 대한 실증 내용을 논하였으며 추가적으로 향후 계획도 포함되어 있다.

• Journal of the Korean Society for Railway
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• v.10 no.1 s.38
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• pp.88-95
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• 2007

TCN(Train Communication Network) adopts the master/slave protocol to implement real-time communication. In this network, a fault on the master node, cased by either hardware or software failure, makes the entire communication impossible over TCN. To reduce fault detection and recovery time, this paper propose the contention based mastership transfer algorithm. Slave nodes detect the fault of master node and search next master node using the proposed algorithm. This paper also shows the implementation results of a SoC-based Fault-Tolerant MVB Controller(FT-MVBC) which includes the fault-detect-logic as well as the MVB network logic to verify this algorithm.