• Journal of Navigation and Port Research
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• v.28 no.10 s.96
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• pp.869-874
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• 2004

Digital TV broadcasting's resolution or tone quality is very excellent than analog broadcasting and has many advantages including various multimedia functions such as home shopping, home banking, internet search, telecommuting, VOD, etc. In this study, it is essential to analyze the regional electromagnetic environment before Digital TV broadcasting, and therefore we analyzed Busan area's limitation using ETRI propagation model. For maintaining high-quality Digital TV signals, we measure electric field intensity wide and far in Busan including mountains area and high-rise buildings. Generally, it has lower value by a standard ETRI propagation model than simulated value about standard model, but distribution pattern are similar with it. Compared theoretical values with the measured results, they have similar values for flat area but very different values for crowded city area and mountains area So we conclude that ETRI propagation model and theoretical model are not suitable for Busan in a free space.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.3
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• pp.563-569
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• 2004

The formulas taking into account the fundamental features of a meteoric radio propagation are obtained. Numerical simulation analysis has shown complex space structure of a field. Time behavior of intensity are researched taking into account nonstationary model. It is shown, this behavior essentially depends on parameters of a meteor trail, and that there is large variety of time dependencies of the signal intensity at the single scattering. In particular, at appropriate parameters of a meteor underdense trail it is possible large duration meteor bursts with which usually refer to an overdense meteor propagation.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.3
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• pp.51-56
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• 2014

TETRA(TErrestrial Trunked RAdio) provide specialized disaster radio communication services as a standard European for digital TRS(Trunked Radio System). Especially, DMO(Direct Mode Operation) feature is used effectively in the radio shadow areas which base station does not propagate radio signal because it can communicate directly with terminal to terminal without base station's relay function. However, to effectively used DMO feature, radio coverage prediction information should be provided to users. Therefore in this paper, we were calculated link budget of TETRA DMO terminals which were distributing and operating in the country and then predicted reaching distance about radio propagation to be applied with path loss model.

• Proceedings of KOSOMES biannual meeting
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• 2005.11a
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• pp.65-69
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• 2005

The theoretical propagation modes of radio waves in the area of Line of Sight(LOS) within Fresnel zone are searched for the available detection ranges in a Marine RFID (Radio Frequency Identification). The structural LOS model to Earth's curvature is proposed and, the calculation method of horizontal distance in a specific radio frequency is also considered in this work As studying results, it is found that the height of antenna to cover the detection ranges and the influences of detection ranges by weather environments can be analyse with the theoretical methods.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.9
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• pp.53-63
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• 1994

In indoor radio systems, vehicular communication systems, and land mobile systems, a very important problem is that of maintaining stable communications at all locations. Therefore solutions for the indoor propagation problem are important aspects of the mobile communication system. leaky coxial cables are finding increasing use in communications systesm involving mines, tunnels, tailroads, and highways, and in new obstacle detection, or guided radar, schemes for ground transportation and perimenter surveilance. In this paper a leaky coaxial cable having periodic slots in the outer conductor is described to obtain the propagation modes in the various environments. We use aneccentric cylindrical model to develop the theory for surface-wave propagation on the cable. Numerical Results are also included for the propagation constants, field distribution and current distribution. First, we derive the electromagnetic equation for leaky coaxial cable having symmetrical periodic slots using mode-matching method and Floquet's theorem, and then find various modes, propagation constants, field distribution, etc.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.6
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• pp.441-448
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• 2018

Recently, measurements on clutter loss due to buildings in urban/suburban areas at 3, 6, 10, 18, and 24 GHz have been performed by the Radio Research Agency with the purpose of predicting the clutter loss close to actual urban/suburban propagation for 5G mobile communication. In this work, we have compared the urban clutter loss to suburban clutter loss for a transmit antenna height of 85 m. Furthermore, we have estimated the error between the predicted loss as per ITU-R P.2108 and the measured clutter loss. Our results indicate that for higher frequencies, the measured clutter loss in urban/suburban areas is higher and so lower than the predicted clutter loss. In conclusion, it is necessary to improve the prediction model for clutter loss by taking into account the measured clutter loss in urban/suburban areas in the prediction model.

• Journal of Advanced Navigation Technology
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• v.17 no.5
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• pp.484-490
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• 2013

With the rapid development of wireless communication at VHF and UHF bands, there is an increasing need for the reliable propagation prediction tools. Therefore, the different propagation models that have been developed in many countries as well as korea has been trying to secure a model suitable for their geographical area but then it is giving us a different result when we compared it to measured values. In this paper, based on the measurements of DTV broadcasting services in domestic urban area, analysis and comparison of ITU-R P.1546 and BCAST models provide errors between measured and predicted values, and some points for improving SMI system has been proposed. As a result, P.1546 model provides the valid predicted data similar to measured data, but BCAST model has some problems of large deviation and higher prediction to measured data. In future, these problems and diffractions due to high buildings need to be studied further.

• Journal of Communications and Networks
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• v.5 no.4
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• pp.309-318
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• 2003

This paper presents an in-depth study of a UWB indoor radio channel between 1 and 9 GHz, which was used for the subsequent development of a new statistical UWB multipath channel model, focusing on short range indoor scenarios. The channel sounding process was carried out covering different indoor environments, such as laboratories, halls or corridors. A combination of new and traditional parameters has been used to accurately model the channel impulse response in order to perform a precise temporal estimation of the received pulse shape. This model is designed specifically for UWB digital systems, where the received pulse is correlated with an estimated replica of itself. The precision of the model has been verified through the comparison with measured data from equivalent scenarios and cases, and highly satisfactory results were obtained.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.226-229
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• 2001

Radio signal tracking has been developed especially in military as well as in other industries. It is necessary that an adaptive system trace the signal varying its PRI and frequency. In this paper we proposed a system to adapt various PRI and frequency using a neural network model named Error Back Propagation. Fist we prepared learning data by separating signal into time intervals and did some experiments with the teaming data. We found that the system had good effectiveness in tracing varying PRI and frequency signals.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.1
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• pp.33-40
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• 2003

Radio frequency management system(RFMS) is being operated to facilitate national spectrum management and monitoring in Korea. To improve the engineering analysis function in RFMS, criteria for the automated selection of the propagation model adequate to the radio station service environment considered are proposed. Those criteria are derived from the specified parameters obtained through the analysis of related ITU-R propagation & diffraction loss models which are to be used in RFMS. Then, using criteria acquired, computer program is made to achieve the automated selection of the most appropriate propagation algorithm, among the ones provided in RFMS, to the environment in which the engineering analysis is required. Furthermore, an illustrative example is shown with the proposals fur increasing the efficiency of the engineering analysis in RFMS.