• Journal of Advanced Navigation Technology
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• v.21 no.4
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• pp.359-364
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• 2017

Since the existing analog village broadcasting system has some technical problems in applying and degradations in performance due to its old equipments, it had been required recently to be changed to a wireless digital system and to develop the standardization. However, it is important to analyze the interference between villages in deploying the efficient digital wireless village broadcasting system. In this paper, simulations for co-channel and adjacent channel interference have been carried out considering digital private mobile radio(dPMR) and digital mobile radio(DMR) systems as a representative mobile radio. These results for frequency reuse and channel separation drawn from the separation distance between villages in co-channel interference and the frequency offset in adjacent interference can be helpful to establish a standard and the testing service in the near future.

• Journal of Korea Society of Industrial Information Systems
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• v.23 no.6
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• pp.59-66
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• 2018

In this paper, we experimented how long distance voice communication is possible After implemented PTT(Push to talk) Bi-directional radio using open source project Codec 2, which is a low speed voice codec for digital amateur radio and 900MHz FSK transceiver. In case of a general digital radio, the AMBE+2 codec, which is regarded as an industry standard in terms of performance, is expensive and has the monopoly of technology. Using the 400MHz band in terms of frequency, narrow bandwidth of DMR(12.5kHz) and DPMR(6.25kHz) is used, so the data rate is low. In the 900MHz bandwidth can be extended, which is advantageous in terms of data transmission. As a result of the voice quality and distance field test, we could find that the communication takes place within about 500m. In this paper, only voice communication is reviewed. if a review of data transmission such as a simple image is added, this solution can be used in various fields as a low cost IOT radio.

• Journal of Advanced Navigation Technology
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• v.19 no.6
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• pp.630-635
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• 2015

Since, the existing analog village broadcasting system had been affected by the climate change such as rain and had some problems likes as short range, it had been changed to the digital system and its standardizations required to be developed from now. In order to deploy the efficient digital wireless village broadcasting system, some propagation profiles as well as service coverages should be analyzed in various radio environments. In this paper, we have set up the transmission power as a parameter and estimated the service coverage area ratio as well as the area ratio interfered into the nearby village in rural, suburban and urban environments using spectrum management intelligence system (SMIS). This paper provides the basic data to establish a standard using the radio propagation characteristics and received power for village broadcasting system in various environments.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.22 no.51
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• pp.139-149
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• 1999

Developed in this paper is a prototype extranet using mobile device such as Personal Digital Assistance(PDA) or Handheld PC(HPC). Especially an adjustment transaction system for auto insurance using wireless data communications is described. Using infrastructures such as PCS, Cellular, Private Radio, wireless communications offers tremendous applications in Korea. A survey of such applications is presented in this paper. Also an analysis of currently available infrastructures of wireless communications is described in this paper. The scheme of an adjustment transaction consists of seven steps: (1) get list of adjustment, (2) obtain insurance information, (3) check police record, (4) get an accident record, (5) get bluebook value, (6) examine the car, (7) file report. Comparing with the previous on-line method that spends much time on gathering data, the proposed system guarantees more rapid transaction using wireless communications.