• Journal of the Korean Institute of Navigation
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• v.17 no.2
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• pp.75-106
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• 1993

GMDSS(Global Maritime Distress and Safety system) is a new communication system for the distress and safety at sea which is utilizing the recent advancements in satellite communication and positioning system, digital communication system, computer and microelectronic technology, etc., and will completely substitute the current communication system by 1999. Although the improvements of education for producing qualified Radio Operators as well as the establi-shments of policy for accepting the system are required, the educational institutions and relating administ-rations have not yet prepared the rational and concrete schemes on the educational methods and accepting procedures for the system. In this study, as the result of analyzing the GMDSS, courses of training and relating data, the authors suggested principles for improving the course and contents of education and rational schemes for balan-cing the demand and supply of Radio Operators. The authors expect not only the consequences of this study can be utilized as reference materials for the instruction to ratio communication in the organs of education but also that the following effects can be obtained by the study. 1. Security of distress and safety communication system at sea by the establishment of relating regula-tions. 2. Rationalization of the management of radio communication at sea and improvement of the communi-cation system on the vessel. 3. Upgrading the quality of Radio Operators and presenting schemes for current qualified persons. 4. Activation of industry producing radio instruments. 5. Balance of the demand and supply of Radio Operators and development of shipping industry.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.275-281
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• 2005

In this paper, a new algorithm is proposed for high speed roaming in an Intelligent Train Control System(ITCS) and study on optimized positioning of radio communication equipment. A DCS(Data Communication System) which is a main part of CBTC(Communication Based Train Control) system, is consisted of radio based wireless communication system and wired optical system. In the radio based wireless communication, the position of AP enclosures and antennas shall be optimized for the guaranteed communication channel between wayside and trains both in open aired and tunnelled area. Also a communication channel established between wayside and train shall be maintained while train moves at its maximum speed. This study shows the way of determining the optimal position for the railway side communication equipment in Bundang Line and how to achieve continuous communicating channel for tracking and controlling train.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.9
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• pp.849-854
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• 2016

5G New Radio Access Technology(: RAT) is studied by many researchers because the current radio frequency is insufficient to accommodate the increased mobile communication data traffic. However, there are few researches to study on the issue whether the wired mobile network can accommodate the new RAT. Therefore, in the paper, the study on the issue whether the Radio over Fiber(: RoF) system can accommodate the new RATs such as millimeter wave communication, terahertz communication, and optical wireless communication. As a result of the study, only millimeter wave communication deserve to be considered in ten years and even RoF system may not support the increased bandwidth of the millimeter wave communication when beamforming is used.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.1
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• pp.110-115
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• 2000

A K-band GaAs MMIC receiver module has been developed using 0.15 ${\mu}{\textrm}{m}$ HEMT technology process. It incorporates two front end low noise amplifiers, a double balanced diode mixer, and filters. The RF input frequency ranges 20.1 to 21 GHz and the IF output 1.1 to 2 GHz. Test results show an overall conversion gain of more than 27 dB, and less than a 2.2 dB noise figure. The image-rejection ratio greater than 21 dB has been obtained. The isolation between RF and IF ports is better than 27 dB, and between LO and IF is more than 50 dB.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1533-1540
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• 2007

The most critical function of the Communication Based Train Control system is wayside and on-board Radio communication. Radio communication must be safely made without errors. The standards for CBTC has not been established yet, and research on Radio communication systems for use in Train control systems adopting CBTC system such as the magnetic levitation train must continue. This paper will discuss the characteristics of Radio communication technology currently used domestically such as GSM-R, IEEE 802.11, TETRA, MESH, and WiMAX/WiBro, and will investigate the potential possibility of applying them to Train control systems.

• International Journal of Railway
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• v.9 no.2
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• pp.36-40
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• 2016

TETRA communication system is very versatile system which can transmit voice + data and packet data optimized. Direct mode operation permits to connect between mobiles when mobile stain is out of coverage of networks. It can be more secure communication channel for railway signaling systems. Railway signaling systems use many of wayside signal equipment, which require many maintenance efforts and budget. Many railway authorities want to reduce and replace the wayside equipment. Radio based signaling systems are one of candidate for replacing the conventional signaling systems. The radio based signaling systems can replace track circuit and wayside signal. The radio systems permit to connect between control centers and trains. The radio systems have to ensure high quality of the connectivity more or equal to the existed track circuits. We studied the application of TETRA systems for railway radio systems for bridging between train control centers and trains. We provide an operation scenario for radio based train control system to ensure the safety require to the existed trains control system and satisfied the existed operational availability. We showed the data transmission speed, maximum bit error rate, and data coding for the radio-based signal system using TETRA systems.

• Journal of Advanced Navigation Technology
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• v.14 no.5
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• pp.745-751
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• 2010

In this paper, the proposed a narrowband interference cancellation techniques for the frequence sharing of Ultra wideband Impulse Radio communication system and narrowband communication system. In this system, the narrowband communication signals can cause intolerant interferences to Impulse Radio signals. In this paper, Ultra wideband Impulse Radio system have been analyzed in AWGN, MAI and NI(Narrowband Interference) environment. Also, performance improvement has been obtained by adopting an adaptive notch filtering scheme using Complex Filter Bank and CCI canceller. The results show that there is a substantial enhancement in performance by employing the adaptive notch filtering and/or CCI canceller.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.11a
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• pp.149-149
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• 2004

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.11a
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• pp.127-127
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• 2004

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.1
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• pp.1-8
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• 2018

It is the content and scope of this study to analyze the problems of the current wireless service and the classification system of the radio station, and to examine the case of radio control in Japan and to establish a reasonable and efficient radio wave management plan. The results of this study can be used as basic data for reorganizing the legislation on radio wave enforcement ordinance, radio services and radio station classification standards. It is expected that it will be possible to improve the compliance and efficiency of the radio station licensing and inspection service while enhancing the policy compliance in the practical work by providing detailed explanations on the definition and classification system of the new radio task / radio station in the future.