• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.4
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• pp.736-742
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• 2003

This paper presents the propagation path loss in a tunnel which is a kinds of underground environments. To predict propagation path loss more accurately, we choose a straight tunnel with rectangular cross-section. The simulated receiver powers that are using a hybrid waveguide model and a Ray-Tracing method, are compared with the measured ones as a function of distance between TX and RX antennas in tunnel. The attenuation value of regression analysis for measured power in the tunnel is 0.0238dB/m which is similar to the one of the EH1.2 mode, 0.0246dB/m in hybrid waveguide model. By comparing simulation with measurement in tunnels, it has been shown that the measured values are approximate to the simulated results of ray-tracing model. In the analysis of wide-band channel characteristics of the tunnel, the more the distance between TX and RX antennas in tunnel increases, RMS delay spread increases and coherence bandwidth decreases.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2000.11a
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• pp.302-305
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• 2000

최근에 ITU-R에서 30～3,000MHz 주파수 범위에서 사용할 수 있는 포괄적인 전계 강도 커브를 제시하고 있다. ITU-R Question 중의 하나인 의제 210/3에서 요구하는 내용은 '30MHz～3GHz 대역의 육상이동과 지상방송 업무를 위한 전파전파 예측절차'이다. 이러한 의제를 WP SG3에서 연구하여 부속서 3K/TEMP/4에 정리하였다. 본 논문에서는 위 부속서 3K/TEMP/4에 나와있는 전송손실 예측 그래프의 적용범위와 적용환경을 알아보기 위해 일반적인 실험적 경로손실 예측식인 Okumura-Hata 모델 그리고 Cost231-Hata 모델과 비교 분석하였다.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2000.11a
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• pp.49-53
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• 2000

본 논문에서는 로그노말 분포된 전파음영 환경에서 통화의 신뢰도를 유지하기 위해 필요한 링크 마진을 경로손실과 전파음영의 감쇠를 포함하는 전파 손실 모델을 사용하여 분석하였다. CDMA 셀룰러 시스템에서 셀 반경이 커지게 되면 요구되는 링크 마진도 증가하게 되어 핸드오프이득은 요구되는 링크 마진만큼 감소하게 된다. 이러한 셀 영역과 링크 마진과의 관계를 하프 핸드오프와 소프트 핸드오프로 나누어 수치해석을 통해 살펴보았다. outage 확플이 0.1이고 셀 반경을 5-10% 증가시켰을 때 전력제어를 한 경우의 셀 영역비는 3.22 dB-3.99 dB, 전력제어를 하지 않은 경우의 셀 영역비는 2.55 dB-2.85 dB 만큼 증가하는 것을 알 수 있다.

• Journal of Convergence Society for SMB
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• v.4 no.2
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• pp.7-12
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• 2014

In this study, we present the investigation results using a 3D radio wave propagation simulator in indoor environments. Previous studies treat only the path loss between the transmitter and receiver in 2D geometry. We provide the simulation results of indoor propagation prediction based on various ITU-R Recommendations. Simulation results compared here indicate that 150MHz and 2GHz frequency bands give quite different characteristics in presented indoor geometry. Since the field intensity is affected by the loss at the wall, the transmitting power level is one of the key factor for receiving power.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.2
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• pp.211-218
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• 2020

The radio wave propagation characteristics of the transmitter and receiver position change in the indoor environment were predicted through simulation, then the results obtained through the transmission loss measurement were compared and analyzed with the simulation results. The conference room was chosen as the environment for measuring transmission loss, and the radio transmission characteristics of the two environments were compared by selecting the exhibition hall without interior decorations and fixtures. In each indoor environment, the position of the transmitter chose two cases. One located in the center of the front wall and the other in the center of the side wall, and the position of the receiver moved along the centerline of the conference room and the side wall, measuring the receiving power. For each change in transmitter-receiver position, received power of 3GHz and 6GHz band were measured and compared with the simulation forecast results. The changes in received power at each receiving point were analyzed according to the location of the transmitter and the frequency band variation.

• Electronics and Telecommunications Trends
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• v.15 no.5 s.65
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• pp.86-93
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• 2000

지하 탐사용 레이더를 이용하여 지하에 매설된 구조물의 위치를 파악하고 그에 따른 근사 이미지의 추출 방법을 제안하였다. 기본원리는 구조물에 의해 산란되어 수신 안테나로 유입되는 펄스신호의 지연시간과 크기를 측정하는 데 있으며, 측정의 실용성을 위하여 레이더 탐색경로에 따른 수신신호의 절대치 적분 방법을 사용하였다. 일반적으로 지하매질은 침투 주파수에 따라서 다양한 분산 및 손실 특성을 나타내는데, 이러한 매질 특성은 다항 Debye 모델을 이용하여 기술되었다. 3차원 전파(電波) 전파(傳播)를 위한 시뮬레이션에는 FDTD(Finite Difference Time Domain) 방법을 사용하였다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.12 s.115
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• pp.1212-1223
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• 2006

Microwave(M/W) bands, though having great demand in wireless services, have been used mostly for long distance communications. As a result, the studies on their mobile radio models have been made less than on VHF/UHF. However, as the mobile communication services with M/W bands have been increasing, the development of a more accurate prediction model of the mobile radio environments has been demanded. The development of a reliable radio prediction model in the mobile radio environments requires the measurement and analysis of the characteristics of the radio waves according to reflection, diffraction and scattering of radio signals in various mobile radio environments. The proposed 8 GHz band radio prediction models have 2 different categories: (1) LOS model and (2) non-LOS model. The LOS model predicts signal strength using the analytic result with measured pathless exponents for the waves direct and reflected by ground and buildings, and the non-LOS model suggests a prediction model of received power by calculating the signal variations after diffraction.

• Journal of Digital Convergence
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• v.11 no.1
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• pp.283-288
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• 2013

In this study, we introduce a 3D micro-cell simulator for radio wave propagation analysis in indoor environments. Previous studies treat only the path loss between the transmitter and receiver in 2D geometry. We provide the simulation results of indoor propagation prediction based on various ITU-R Recommendations. Simulation results described here indicate that the low and high frequency bands give quite different characteristics in presented indoor geometry. The propagation loss as a function of distance has two distinct regions. It is similar to that occurring in free space within 5-20m of the transmitter, however, increases significantly as the electromagnetic waves become obstructed by the walls at distances further away in the next region.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.6
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• pp.1031-1040
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• 2023

Propagation characteristics in line-of-sight(LOS) paths in 3, 6, 10, and 17 GHz frequency bands were measured and analyzed in two different indoor corridors: second floors of Buildings D2 and E2. The measurement was designed to measure when the receiving antenna moved at 0.5 m intervals from 3 m to 30 m, while the transmission antenna was fixed. The analysis of the two indoor corridors was compared by applying basic transmission loss, root mean square (RMS) delay spread, and K-factor. For basic transmission loss, the loss coefficient of the floating intercept path loss model was higher in the indoor corridor of Building E2 than in that of Building D2. Similarly, the RMS delay spread in the time domain was greater in the indoor corridor of Building E2. However, the indoor corridor of Building D2 exhibited higher K-factor in the 3, 6, and 17 GHz bands with lower wave propagation in the 10 GHz band. Despite the 2 indoor corridors being identical, the propagation characteristics varied due to different internal structures and materials. The results provide measurement data for ITU-R Recommendations regarding various indoor environments.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.7
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• pp.693-701
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• 2002

In this paper, we analyze the coverage of asynchronous IMT(International Mobile Telecommunication)-2000 reverse link with a MUD(Multi-User Detector) system. The MUD system is utilized to increase the coverage of reverse link. Also we have considered a propagation loss model and an interference effect. Because it is very difficult that we have calculated the interference accurately, so a fractional cell loading factor(F) is used in this paper. We make use of a MUD efficiency($\beta$) to analyze the performance; this efficiency is presented the MAI of reduction. A simulation utilizes Hata's model, we calculated the coverage according to voice and data services. In this paper, we have assumed that the frequency of carrier has 800 MHz or 1.9 GHz, and a bandwidth is decided 3.84 MHz. We have predicted the performance of actual system by the analysis of capacity and coverage.