• 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 Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.5
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• pp.426-435
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• 2002

In this paper we present an indoor propagation model for indoor wireless LAN service in the ISM band. We primarily use a 3D ray tracing as well as a patch scattering model in order to take into account the indoor fixtures. Therefore input parameters such as indoor environment parameters and antenna's types, polarizations are considered. As the results, we present fading characteristics and rms delay spread from time delay spread. In order to investigate the accuracy of the presented model, comparisons of predictions with measurement and simulations are performed in indoor wireless LAN service environments. The results show that measurements and simulations are very similar. Therefore in this paper, the effect of presented indoor propagation model is confirmed.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1998.05a
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• pp.145-152
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• 1998

실내에서 가스폭발시 피해를 예측하기 위해서 폭발 화염면의 전파를 수치해석을 통해 해석했다. 확산방정식에 의해 가스누출에 의한 실내의 가스확산분포를 구했으며 문헌에서 선택한 누출의 초기조건을 사용했다. 화염온도를 계산하기 위해 각 가스 혼합비에 따른 엔탈피와 화학식에 대한 reduced mechanism을 사용했으며 문헌에서 찾은 각 가스의 농도별 층류 연소속도를 혼합가스의 층류연소속도에 적용시켰다. k-$\varepsilon$ 모델에서 turbulance energy를 층류연소속도와 결합시켜 난류화염 전파속도를 모델링 했다. 화염면의 전파를 분석하기 위해 실내의 위치에는 직각, 화염면의 전파에는 원통좌표계를 사용했다. 유리창의 파손에 의한 화염전파면의 변화에 따른 압력상승 요인을 해석하였으며 창문의 크기에 따라서 점화위치에 따른 실내 압력상승의 영향이 서로 다르게 나타나는 결과를 얻었다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.1
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• pp.133-141
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• 1999

In this paper, we present an indoor propagation prediction model which is based on a three-dimensional ray-tracing technique. In this model, instead of considering all obstacles such as furnitures and fixtures, etc., only main obstacles to the propagation such as walls, ceiling and floors are modeled as slabs with finite thickness and conductivity, and the significant phenomena of propagation are considered, so we can calculate simply and predict accurately the propagation losses. The propagating rays are considered to be reflected and transmitted specularly at the boundaries of obstacles, and diffracted at edges. The reflection and transmission losses on flat obstacles are calculated by using ray tracing method, and the diffraction losses at edges are calculated by using the uniform theory of diffraction (UTD) for finite conductivity media. The results simulated for some cases by this propagation model good agree with the measured value of pathloss.

• 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.

• Journal of Energy Engineering
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• v.3 no.1
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• pp.62-69
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• 1994

화염중에 존재하는 이온 및 전자의 전기적 성질을 이용하여 연소실내의 화염전파속도를 파악하기 위해 실린더 헤드에 이온 프로브를 삽입하여 천연가스 및 가솔린의 화염전파속도를 측정하였다. 본 연구에 이용된 이온전류장치 설계에 의한 방법은 광학적 측정 장비에 비해 간단하며 쉽게 측정할 수 있고 가격도 저렴하고 응답성도 우수하였다. 이온 프로브의 제작과 신호처리에 관한 기초적인 지식을 얻었으며 천연가스 및 가솔린의 연소시 연소압력의 상승지점과 이온발생지점이 일관성있게 나타났다. 기관회전수의 증가에 따라서 연소실내의 화염전파속도가 증가했으며 같은 연소조건이라고 할 수 있는 동일 기관회전수, 당량비의 조건에서 점화시간에 대한 화염전파속도를 비교해 보면 메탄의 경우가 이론치보다 6 ms∼9 ms 정도 늦었다. 또한, 메탄가스 및 가솔린에 대해 이온 전류강도 및 화염 도달시간을 측정하였으며 연소실 벽면에서는 열전달에 의한 냉각효과로인해 화염 전파속도 및 이온농도가 감소했다.

• 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.

• Journal of the Korea Computer Industry Society
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• v.3 no.5
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• pp.547-556
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• 2002

This paper was proposed a wave path loss prediction algorithm using multilayer perceptron (MLP) model and wave propagation characteristic parameters for Wireless LAN in indoor radio environments. Receiving power was predicted by calculating indoor path loss in a Wireless LAN that has transmission power of 100mW and frequency of 2.4GHz, and was compared with measured. In the result of measurement shows that there is a difference between predicted and measured receiving power which can be reduced by an accurate analysis of the various path loss factors. In order to fix the access point(AP) positions was used the proposed a wave path loss prediction algorithm, and designed the optimum cell for Wireless LAN.

• Proceedings of the Korea Information Processing Society Conference
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• 2017.11a
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• pp.99-101
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• 2017

최근, 실내 환경에서 위치기반 서비스 응용에 대한 수요가 늘어남에 따라 비콘, 지자기, Wi-Fi 등을 사용한 실내측위 관련 연구가 활발히 연구되고 있다. 특히, BLE 비콘을 사용한 실내측위는 시스템 설치 및 유지보수의 용의성, 낮은 소비전력, 낮은 가격 등의 특징을 가지고 있으며, 이에 다양한 상용 실내측위 응용 분야에서 조명 받고 있다. 일반적으로, BLE 비콘 기반 실내측위는 단일 BLE 비콘과 해당 비콘의 전파 범위에 위치하는 단말기 사이의 송수신 전파의 세기 정보를 이용하여 절대 거리를 계산한다. 그러나, 기존 연구 방법으로는 BLE 비콘의 종류, 설치 환경에 따른 전파 감쇄 및 반사 등의 문제로 정확한 거리를 측정할 수 없다. 본 논문에서는 다중 비콘을 사용하여 각 비콘으로부터 얻은 수신세기 차이를 이용한 실내 공간 세그멘테이션 방법을 제안한다. 본 논문에서 제안한 방법으로 실험을 진행하였으며, 그 결과 임의로 설정한 $4m{\times}4m$ 정사각형 영역에서 내부와 외부를 구분할 수 있었다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.7
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• pp.733-740
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• 2008

In this paper, an indoor propagation model based on 3d ray tracing is presented for wireless communications. In case of indoor propagation models, various radio propagation paths such as wall-transmitted wave and scattered wave from ceilings, pillars, and furnitures arises and 3-D formulation is needed. To accommodate such scatterers, objects are modeled by triangulated surfaces and ray tubes using those surfaces are introduced and efficient calculation methods using the tubes are presented.