• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.351-355
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• 1999

서비스 반경이 1이내인 마이크로셀 방식은 기지국의 송신출력을 가능한 작게 하고 안테나의 위치를 주변 건물의 높이보다 낮게 설치하기 때문에 셀 반경내에 있는 지형과 구조물들은 전파특성에 매우 큰 영향을 주므로 셀 내 지형지물의 특성에 따라 기지국의 최적 출력을 구할 수 있는 전파예측 모델이 필요하다. 본 연구에서는 이동국이 가시거리 영역의 전파 음영지역 또는 가시거리 영역과 일정 경사각으로 기울어져 있는 비가시거리 영역에 위치한 경우로 구분하고, 기지국으로부터 송신된 신호가 이동국까지 일정 직진경로를 전파하는 동안, 전파의 반사첫수와 전파경로를 계산할 수있는 연산처리 알고리즘을 개발하여, 이를 웅용하므로써 임의 지점에 위치한 이동국에 도래하는 수신전력을 예측할수 있는 모델을 제안한다. 그리고, 마이크로셀 이동통신 전파환경에서 개발 알고리즘과 제안 전파예측 모델을 시뮬레이션하여, 그 결과를 분석함으로써 마이크로셀 기지국의 최적 위치선정 조건과 기지국 출력에 따른 가입자 서비스 조건을 제시한다.

• The Journal of the Acoustical Society of Korea
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• v.22 no.7
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• pp.579-584
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• 2003

All of propagation path loss prediction models, which have been presented up to date, are oかy for ground living space. In reality, sea surface free space is different from ground living space in physical hierarchical structure. If the propagation path prediction model for ground living space is applied to the sea surface free space, propagation path loss will be smaller than actual value, while the maximum service straight line will become shorter. Thus this paper proposed and simulated the propagation path loss prediction model for predicting propagation path loss more accurately in sea surface free space, with its focus on CDMA mobile communication frequency band. Then the simulation results were compared to actual survey to verify its practicality.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.1
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• pp.173-178
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• 2020

A multi-ray model has been used to interpret radio transmission losses in half-canyon structures with slope and to formulate a multi-ray propagation model depending on the angle of slopes. The cut-off angles for the third and fourth paths, which are the slope-sided reflection paths of the transmission and reception radio waves determined by the inclined angles of the slope, were calculated with the height and location of the transmitter and receiver. To predict transmission losses in an inclined plane environment, the embankment environment where the actual slope exists was modeled and simulated to calculate the loss of propagation transmission, and the radio wave transmission loss was confirmed by the measurement for the frequency band 1 to 6 GHz. Simulation results and measurement results showed similar trends in radio transmission loss, and radio transmission loss predictions and measurement results for various terrain information can be used in the design of radio propagation service.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.14 no.4
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• pp.293-306
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• 1989

In this paper, the models and characteristics of multipath propagation in an urban environment are described. Three propagation models(a random model, a ray model and a method of estimating time delay is proposed based on the envelope correlation between two radio frequencies. It is shown on the basis of laboratory simulation and field tests that the simple two-ray model is an adequate model for the fundamental study of the multipath propagation characteristic of the mobile radiowave and the estimating time delays of multipath-propagated waves in an urban area.

• The Journal of the Korea Contents Association
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• v.4 no.2
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• pp.21-27
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• 2004

In an urban area telecommunication using wireless system, the accurate prediction and analysis of wave propagation characteristics are very important to determine the service area optimized selection of base station, and eel design, etc. In the stage of these analyses, we have to present the propagation prediction mood which is varied with the type of antenna, directional angle, and configuration of the ground in our urban area in addition we need to perform an analysis of the conventional mode which is similar to ours and dig out the parameters to evaluate the wave environment before the cell design for the selected area. In this paper, we propose a wave propagation prediction model concerning the topography and obstacles in our urban area. We extract the parameters and apply them to the proposed wave environment for the simulation analyzing the propagation characteristics. Throughout these analyzing procedure, we extracted the essential parameters such as the position of the base station, the height of topography, and adequate type and height of the antenna with our preferable cuteness.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.9
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• pp.811-820
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• 2012

GNSS signal is vulnerable to jamming signal because of well-known signal structure and weak signal power. For these reasons, the need for analysis of jamming effects and anti-jamming techniques of is increasing. In this paper, a GNSS signal generator is designed which includes a radio wave propagation model for six kind of tactical environments and a body masking model for the reception environment of a vehicle. The radio wave propagation model for downtown, rural, forest, coastline, waste land and snow or ice area is designed using two-ray model. The body masking model is designed the effect which the antenna is affected by the reception environment of a vehicle and radiation pattern from a user configuration. The performance of generated signals from the GNSS signal generator considering reception environment of a vehicle is evaluated by a commercial GPS L1 receiver(NordNav) in normal and jamming environment. Also, the generated GNSS signal is compared to a commercial GPS L1 H/W based RF signal generator(STR4500). The results show that the designed GNSS signal generator in a normal environment compared to the same navigation performance. In jamming environment, it is shown that the body masking effect and GNSS signal acquisition and tracking loss in compliance with the jamming signal are precisely working in the reception environment of a vehicle.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.4
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• pp.379-386
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• 2012

The primary aim of this paper was to evaluate several probabilistic fatigue crack propagation models using the residual of a random variable, and to present the model fit for probabilistic fatigue behavior in Mg-Al-Zn alloys. The proposed probabilistic models are the probabilistic Paris-Erdogan model, probabilistic Walker model, probabilistic Forman model, and probabilistic modified Forman models. These models were prepared by applying a random variable to the empirical fatigue crack propagation models with these names. The best models for describing fatigue crack propagation behavior in Mg-Al-Zn alloys were generally the probabilistic Paris-Erdogan and probabilistic Walker models. The probabilistic Forman model was a good model only for a specimen with a thickness of 9.45 mm.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.3 no.2 s.5
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• pp.1-8
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• 2004

Characteristics of digital broadcasting are multi-channel, high-definition and multi-function. especially, multi-function is enable us to do a variety of services except for an image and a voice. This paper, therefore, is analyzed propagation environment in Busan into ETRI model application about 지상파 DMB service. It takes to be simulated in Busan area around the mountains area and high building. So it measures the electric field strength in standards. Distribution pattern are similar with mutually in the 이론 and real measurement. Even areas are almost the same, but urban areas and mountains are different with mutually. Therefore, we conclude that ETRI propagation model and theoretical modeling in a free space in Busan area is not suitable.

• The Journal of the Acoustical Society of Korea
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• v.16 no.4
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• pp.49-56
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• 1997

In mobile communications, it is very important that we predict the propagation environments of radiation pattern, in order to decide the service area, select the best location of the best station, design the cell etc. Therefore, by analyzing the propagation prediction model that is varied according to the kind of antenna, the beam angle, the terrain and obstacles, we expect that the economic operating of communication networks, the calling quality and the service of subscriber will be enhanced. In this paper, we select the around of Seji base station in Naju-city Chonnam for modern suburban area and measure the field strength to propose the optimal propagation prediction model for suburban areas. We propose the propagation prediction model that, it is not found in the other models until now, consists of the correction coefficient with the relative differences of antenna effective height of the base station and mobile station for minimizing errors. Finally, comparing the results of the field test with the computer simulation(PPGIS : Propagation Prediction Geographic Information System) results for the Hata model, the Egri model, the Carey model and the propose model, we confirm the property of the proposed model.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.5
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• pp.688-693
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• 2022

In this paper, channel propagation path loss was measured in building corridors for frequency bands of 3.7 GHz and 28 GHz, which are used in 5G mobile communication, and compared and analyzed with CI (Close-In) and FI (Floating-Intercept) channel models. To measure the propagation path loss, the measurement was performed while moving the receiver (Rx) from the transmitter (Tx) by 10 m. As a result of the measurement, the PLE (Path Loss Exponent) values of the CI model at 3.7 GHz and 28 GHz were 1.5293 and 1.7795, respectively, and the standard deviations were analyzed as 9.1606 and 8.5803, respectively. In the FI model, 𝛼 values were 79.5269 and 70.2012, 𝛽 values were -0.6082 and 1.2517, respectively, and the standard deviations were 5.8113 and 4.4810, respectively. In the analysis results through the CI model and the FI model, the standard deviation of the FI model is smaller than that of the CI model, so it can be seen that the FI model is similar to the actual measurement result.