• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.9
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• pp.791-801
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• 2012

Currently, SEAMCAT has been widely used as a tool to evaluate the effects of interference among a variety of wireless communication systems. This supports various channel propagation models, all of which are based on some statistical models for the channel propagation and do not exploit any specific terrain characteristics. Thus it is not appropriate for assessing the effects of interference between wireless systems, given some specific terrain features. In order to overcome this limit in its use, it is necessary to extend the capability of SEAMCAT to support a channel propagation model which takes into account terrain informations. The ITU-R P.526 is a familiar channel propagation model which calculates the path loss considering the terrain features. In this paper, we present an enhanced version of SEAMCAT which supports the ITU-R P.526 and provide a few examples of interference evaluation using it.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.5
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• pp.703-713
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• 2022

Accurate and rapid establishment of mobile communication is important in mobile communication system. Currently, the base station parameters to establish a network are determined by cell planning tool. However, it is necessary to perform new cell planning for each new installation of the base station, and there may be a problem that parameters are not suitable for the actual environment are set, such as obstacle information that is not applied in the cell planning tool. In this paper, we proposed methods for path loss prediction using DNN and topographical division using CNN in SON server. After topography classification, a SON server configures the base station parameters according to topography, and update parameters for each topography. The proposed methods can configure the base station parameters automatically that are considered topography information and environmental changes.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 2003.12a
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• pp.121-127
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• 2003

본 논문에서는 Internet Service Provider(이하 ISP)의 네트워크에 위험이 발생할 경우 위험의 출현으로 인한 ISP의 자산손실을 추정하는 방법을 제안한다. ISP의 네트워크를 구성하는 자산들의 가치를 서비스 측면에서 분석하고, 개별 자산이 생산하는 서비스 가치를 근사할 수 있는 방법론을 제시함으로써 네트워크의 장애로 인한 손실액을 추정 가능함을 보인다. 또한, 네트워크의 부하 분산, 우회 경로 및 백업 시스템 등 서비스 연속성을 확보를 위한 잉여 설계가 있을 경우, 자산가치 특성함수를 사용한 손실액 추정모델을 제안한다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.5 s.108
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• pp.490-499
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• 2006

In this paper, we present the newly developed propagation toss model of a long range maritime communication channel, measured by a ground to air flight test, and discuss its validity compared with the predictive value based on the spherical earth reflection model. To measure the propagation loss, actual flight test was performed in the Yellow Sea and the measurement of receiving signal strength was made for overall test range. As far as the test condition is concerned, it is expected that the receiving signal strength must be interfered with the reflected wave by an island existing around the reflection point. Therefore we introduce some modifications on the conventional spherical earth reflection model by including the effect due to the reflected wave from the island. And then, we compare the path loss measured by flight test with that one analyzed by the spherical earth reflection model accounting for reflected wave of the island. As a result of the comparison, it is verified to predict the path loss accurately by the spherical earth reflection model including the effect due to the reflected wave from an island for a long range ground to air communication.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.11b
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• pp.1123-1126
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• 2002

연구와 군사 목적으로 발전한 인터넷은 현재 많은 기업들과 일반인들이 사용하는 현대 사회의 중요한 기반 시설로 자리잡게 되었으며, 아울러 인터넷이 사회에 끼치는 영향이 커짐에 따라 여러 가지 목적으로 자신의 접속 위치를 우회하여 숨기고 인터넷 보안 모델의 취약점을 공격하는 침입자가 증가하고 있다. 따라서, 침입에 사용되는 기술과 그에 대한 대응 기법 또한 보다 복잡하고 정교해 지고 있으나 근본적으로 악의적 침입을 근절하는 능동적인 대응은 미약한 현실이다. 본 논문에서는 인터넷 환경에서 여러 가지 우회 경로를 통해 접근한 침입자의 실제 접속 위치를 효율적으로 추적하기 위해 기존 역추적 연구의 유형과 문제점을 살펴보고 차세대 인터넷 환경에서 활용 가능한 역추적 기법의 모델을 제시한다. 따라서, 기존 역추적 기법의 현실적으로 적용이 어려운 구성과 침입자의 보안 설정에 따른 추적 제한 등의 문제점을 살펴보고 그 해결 방안이 되는 새로운 역추적 시스템의 모델을 제시한다. 그리고, 본 연구에서 제시하는 모델은 기존의 연결 경로를 거슬러 추적하는 기법과 달리 프록시 등 우회 경로를 통해 접근한 침입자에 대해 직접 연결되는 프로토콜을 자동 실행 되도록 구성하여 접근한 침입자의 위치를 파악하는 모델이나. 이 모델을 적용할 경우 실제 적용 가능한 구성과 효율적인 추적 특성을 가지게 되며 구성 비용의 손실 또한 줄일 수 있게 되는 장점을 가지게 된다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.5 s.108
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• pp.430-439
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• 2006

This paper presents the a measured path-loss characteristics for mobile communications beyond 3G in microcellular residential area and street microcell at 3.4, 5.3, and 6.4 GHz band signals. The residential area is divided into two sections, one of which is composed of fifteen-story appartment buildings. The other section comprises four-story houses. The street microcell is classified line-of-sight(LOS) and nonline-of-sight(NLOS) areas. Both residential areas have standard deviations independent of the residential area classification, whereas the path loss exponents in the apartments is higher than those in area for same frequencies. A two-ray model is applied to analyse the path-loss charateristics in LOS areas. In LOS areas, an empirical breakpoint, whose distance is 6 percent shorter than a theorical breakpoint, is founded. Further, a sudden power level drop occurs at a transition point from LOS region to NLOS area. Path loss exponent is found to be significantly higher for non-LOS region than for LOS region. The power level drop due to corner loss and path-loss exponents both increase as the distance between the transmitter and the corner increases.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.11B
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• pp.1847-1857
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• 2000

통신의 연속적인 경로를 구성하기 위하여 광케이블의 상호접속점이 존재한다. 광섬유를 접속하는 과정에서, 두 광섬유 코어의 중심 축이 일치하지 않아 광 손실이 발생하게 되는데, 본 논문에서는 광섬유의 절단면의 형태에 따라 score, lip, roll off, chip, end angle, valley 모양으로 분류하고, 그 손실관계를 비교 분석하여, 광섬유의 절단면 불량으로 인한 재접속을 줄이기 위하여 불량여부를 쉽게 판정할 수 있는 융착접속 화면 개선 모델과 절단면의 형태별 접속허용 판정기준을 제시하였다.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.429-432
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• 2002

천해에서의 저주파 단상태 잔향음 모델(L-HYREV)을 개발하였다. 음선이론에 기초한 전파모델은 해저 내로 투과되는 음파에 대한 효과를 적절하게 고려 할 수 없으므로, 해저 내 상호작용을 계산할 수 있는 전파모델이 필요하다. 따라서 본 논문에서는 RAM을 이용해서 전달손실을 계산 후, 다중경로 확장모델을 이용해서 산출한 전달손실을 보정하였다. 모델의 검증을 위하여 GSM(generic sonar model) 잔향음 모의 신호 및 실측잔향음 신호와 비교하였으며, 비교 결과 GSM 보다 L-HYREV 모델이 저주파 잔향음 예측에 적합함을 확인할 수 있다.

• 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.

• 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.