• Journal of the Korean Society for Railway
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• v.15 no.4
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• pp.364-369
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• 2012

This paper presents an experimental study on the radio propagation characteristics in subway tunnel at 18GHz frequency band which has been assigned to video transmission between train and wayside. The radio propagation tests are carried out in the subway tunnel of Seoul Metro using the antenna and communication devices of the prototype video transmission system. The measurement results show that 18GHz radio propagation in subway tunnel has smaller path loss than that of general outdoor radio environment. It is also cleared that the arch-type tunnels have smaller radio propagation losses than rectangular tunnels, and single track tunnels have smaller pass loss than double track tunnels. From the measurements, the radio propagation coverage is worked out as 520 meters. The curved tunnels which cannot have LOS communication between transmitter and receiver have large pass losses and fluctuation profile along distance. The radio propagation coverage along curved tunnels is worked out as 300 meters. These investigation results can be used to design the 18GHz radio transmission system for subway tunnel by providing the optimized wayside transmitter locations and handover algorithm customized to the radio propagation characteristics in subway tunnels.

• Journal of the Korean Institute of Landscape Architecture
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• v.44 no.2
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• pp.96-107
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• 2016

This study is an attempt to trace the origins of Korean botanical gardens prior to the construction of the botanical garden in Changgyeonggung Palace. We trace the time period during which Korean intellectuals first understood and appropriated botanical gardens based on accounts found in travel journals. These were written by members of delegations sent to Japan, Russia, and Great Britain and by students who had studied abroad, such as Tchi-Ho Yun and Kil-Chun Yu, during the open port period from 1876 to 1910. This study shows that the term "botanical garden" did not appear in any of the travel journals and the delegations did not show much interest in them until the 1880s. Japan had planned to introduce the different types of botanical gardens to the delegations from the Joseon Dynasty, but the delegations left no official records or related accounts regarding their visits. In contrast, members of delegations who were sent to Russia, Europe, and America after the 1890s began to pay attention to botanical gardens. They considered botanical gardens as a representative and essential part of Western culture and attempted to introduce them in Korea as essential tools for academic development as well as for enlightenment. Although many Korean intellectuals' opinions about the necessity of a botanical garden did not actually lead to its construction during the open port period, such a movement was significant in that it strengthened the botanical garden's image as a symbol of civilization. Apart from tracing the origins of the botanical gardens in Korea, this study serves as fundamental research material for understanding the establishment of the Changgyeongwon Botanical Garden in 1909.

• The Journal of the Acoustical Society of Korea
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• v.35 no.3
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• pp.167-174
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• 2016

Underwater communication is difficult to increase the communication capacity because the carrier frequency is lower than that of radio communications on land. This is limited to the bandwidth of the signal under the influence of the characteristics of an ocean medium. As the high transmission speed and large transmission capacity have become necessary in the limited frequency range, the studies on MIMO (Multiple Input Multiple Output) communication have been actively carried out. The performance of the MIMO communication is lower than that of the SIMO (Single Input Multiple Output) communication because cross-talk occurs due to multiusers along with inter symbol interference resulting from the channel characteristics such as delay spread and doppler spread. Although the adaptive equalizer considering multi-channels is used to mitigate the influence of the cross-talk, the algorithm is normally complicated. In this paper, time reversal mirror technique with the characteristic of a self-equalization will be applied to simplify the compensation algorithm and relieve the cross-talk in order to improve the communication performance when the signal transmitted from two channels is received over interference on one channel in the same time. In addition, the performance of the MIMO communication based on the time reversal mirror is verified using data from the SAVEX15(Shallow-water Acoustic Variability Experiment 2015) conducted at the northern area of East China Sea in May 2015.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.18-18
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• 2017

ISO11783은 농업 산업분야 통신 프로토콜의 국제 표준으로, 농용트랙터 및 작업기 ECU 간의 통신 프로토콜을 표준화한다. 이 표준은 서로 다른 제조사의 제품 간에 호환성을 갖게 하며, 정밀 농업에 대한 핵심 기반을 제공한다. 현재 해외에서는 이미 ISO11783 기반의 AFS(Advanced Farming System)를 통한 정밀농업이 상용화되어 농가에 보급되고 있다. 이에 비해, 국내에서 이러한 표준을 따르는 농기계들은 미비한 실정이며, 향후 농업의 정밀 농업화를 통한 고부가가치 창출 및 선진국의 무역 장벽에 대비와 해외 수출 판로 개척을 위해 ISO11783 표준에 대한 R&D가 필요로 한다. 이에 IsoAgLib를 분석하고 임베디드 보드에 Porting하여 ISO11783 기반 작업기 ECU를 구현하였고, 이를 기반으로 ISO11783 기반 작업기 ECU의 구현 방법을 발표한다. IsoAgLib의 시스템 아키텍처는 계층화 되어 있어, 타겟에 의존적인 계층만 수정하여, IAR 환경에서 Cortex M3 보드에 포팅을 완료하였다. 작업기 ECU들은 자신만의 인터페이스 화면을 갖으며, 이를 Object pool이라 한다. 이것을 Virtual Terminal(VT)에 업로드 하여, VT가 해당 작업기 ECU의 사용자 인터페이스 기능을 제공하도록 한다. 이에 작업기 ECU 구현 1 단계로, 'VT-Designer'를 통하여 Object pool를 설계한다. 2 단계, 'vt2iso'를 통해서 Object pool을 IsoAgLib 상에서 사용할 수 있도록 변환한다. 3 단계, 포팅된 IsoAgLib project에 변환된 파일을 포함 시킨다. 4 단계, 작업기 ECU의 주기적인 작업 및 각 메시지 수신시 수행할 작업을 코딩한다. 5 단계, 빌드 및 타겟 보드에 업로딩 한 후, New Holland 사의 $Intelliview^{TM}$ iv display (VT)과 연결하여 동작을 확인한다. 확인 결과로 VT에 디자인한 Object pool이 표시 되며 soft key 입력 시 작업기 ECU에서 LED가 변한다. 결론적으로, 연구 결과를 바탕으로 ISO11783 기반의 작업기 ECU의 디자인 및 구현이 가능하며, 이를 통해 향후 국내의 ISO11783 기반의 작업기 ECU의 개발에 도움을 줄 수 있다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.6
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• pp.871-881
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• 2001

In this paper, the effect of soft handoff technique on CDMA cell coverage is analyzed in a lognormally shadowed channel, which uses the Hata propagation model, Also, the rate of increase for the cell coverage is analyzed by calculating the hard and soft handoff margin. When the outage probability is 0.02 and the standard deviation of the received signal is 2.5 dB in a lognormally shadowed channel, the transmit power of the mobile station which is located in the cell boundary is increased by the hard handoff margin of 5.13 dB and by the soft handoff margin of 3.68 dB, respectively. So, the rate of increase for the cell coverage is 1.39 in case of using the soft handoff technique. It is shown that if the (E$\_$b//N$\_$0/)$\_$req/ value is 7 dB, the cell coverage of the CDMA cellular system with soft handoff technique in city area is 3.33 km in case of the 850 MHz frequency and 1.36 km in case of the 1900 MHz frequency. Also, the accurate cell coverage with soft handoff technique is supported that could be serviced by the base-station in CDMA cellular system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.2 no.4
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• pp.545-551
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• 1998

The Radio communication by existing SSB, VHF, etc. in a coast station and a base station for military affairs is still used to a very important the device of information delivery or transmitting and receiving by the remote controller to using to the exclusive cable for a equipment established at a long distance. When a number of consumer to connected and operated by a number of transceiver is essential for a circuit controller of ICS, in KOREA, is devoted by import to considerable quantity because of to be delayed development of this field. This Paper has been realized to optimal algorithm and designing of a circuit connection controller by multi-processor to pre-stage for the development of ICS. The H/W is composed able to remote control to circuit connector with the several slave processor and a processor for master, and this has taken possible through without any obstacle to communication circuits of a control signal by FSK system. The S/W make possible monitoring for communication condition of other circuits by means of a serial communication system by the multi-processing. This paper has been studied for connecting to a circuits wished to rapidly and precisely by the full application to a interrupt technique. A technique to control by remote to a number of transceiver is a way increasing to application for a frequency resource of the limited MF/SF, VHF and the existing radio communication technique. According to, this paper will achieve to be the reduction of energy & equipment and multiplicity of information delivery in the general communication and disposal to rapid and exact for the important communication as distress, urgency and safety on the sea.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.8
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• pp.1620-1625
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• 2004

To advance fisheries, we set developmental directions of fishery information by grasping present situations and analyzing maritime & fisheries issues. We promote various policies through effective systematical information data bases, based on both control and utilization of oceanic resources. For these puposes, it is imperative that we set up fisheries communication networks. There are satellite assisted informational networks to assist fishing vessels with their marine based movements. However, there's no hope for poorly equipped fishermen to adopt this network because of extravagant network call charges. So we think that using existing SSB communication system is the best plan. We organize fishery communication network by HF SSB communication which doesn't have operational costs. We build wireless transmitting and receiving stations that are basic systems of informnation, and equip wireless data communication systems by the use of wireless communication network protocols in coastal stations. It is necessary that a fish boat has a terminal device for wireless data communication. In this research we can conclude that if we transmit the location of a fishing boat in-real time through GPS channels then we propose that some methods be formulated to able terminal devices on fishing boats to collect various types of information, such as meteorological and oceanic conditions.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.4
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• pp.833-838
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• 2011

RFID system in manufacturing industry is used to collect, categorize, and process the data of products. To install RFID system for a large factory, a large amount of wired data communication network is necessary for RS232 communication. If the installed location of RFID system in the factory is changed or extended, a reinstallment is required for the already installed wired data network. A large amount of time/financial reinvestment is necessary for such reinstallation. By using wireless data communication network, however, the initial installation and reinstallation are very simple. In this paper, we implemented a wireless communication system and RFID system. We used the CC1020 chip for wireless communication system and EM4095 chip for RFID system. CC1020 chip enables highly-reliable data communication, and by setting a simple status register, it can switch between transmitting/receiving status and it can choose the desired frequency of either 400 MHz or 900 MHz. Also, Communication range is 50 m, if external antenna is used. EM4095 is a chip for RFID reader system with the carrier frequency of 125 KHz. This chip can implement the reader system by connecting a small number of components. And EM4100 was used for RFID system. EM4100 is read-only type. Atmega128 is used to control a wireless communication system and RFID system. We confirm that the system can communicate without error up to 50 m from sender. In the paper, the circuit diagram and operation program for CC1020 and RFID system are presented. The system used in the experiment is shown in pictures, and the data movement pattern of CC1020 is shown in the diagram, and the performance of each transmission method is presented.

• Journal of Satellite, Information and Communications
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• v.3 no.1
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• pp.41-47
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• 2008

Line-of-sight communications cannot easily support korean armed forces because of mountainous terrain. ADD(Agency for Defense Development) introduced ANASIS(Army Navy Air-force Satellite Information System) to meet the Korean warfighter's operational needs. Currently, army's military satcom terminal is designed for either fixed site or on-the-pause operation. The US army is under development of multi-band integrated on-the-move satellite terminals to let the army's communication capability to keep pace with globally deployable Joint Task Force for network-centric application. In this paper we analyzed X-band and Ka-band link and subsystem requirement. Our focus here is to describe key technical issues. Especially, On the basis of 3dB beam width of 0.9m antenna, Tracking accuracy and disturbances compensation signal processing on-the-move of Antenna Tracking system is analyzed. Also, protocol is analyzed that minimize blockage on the move due to an obstacle. when the received signal blocked, it stop to transmit burst signal and retransmit when blockage removed through received synchronization signal monitoring. Analyzed specification will be used to make prototype terminal to analyze risk for mass production

• Journal of Astronomy and Space Sciences
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• v.25 no.1
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• pp.53-60
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• 2008

A RF environmental field test for the proposed Galileo Sensor Station site was done by Alcatel Alenia technical team contracted by European Space Agency (ESA) and the Space Geodesy division of Korea Astronomy and Space Science Institute at the Korean VLBI Hetwork (KVN) site in Tamla University Campus, Jeju from June 21, 2007 to June 24, 2007. Full band and in-band 24 hour observation for radio frequency interference, precise positioning, and multipath on three proposed antenna locations for Galileo signal were executed. The main purpose of this survey is to verify the results of previous test on 2006 by KASI. The preliminary analysis of the results and a full investigation also had been done by ESA under the permission of KASI until the end of July, 2007.