• The Journal of the Korea institute of electronic communication sciences
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• v.5 no.3
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• pp.233-238
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• 2010

In this paper, we have proposed discrete ray tracing method (DRTM) for numerical analysis of characteristics of electromagnetic propagation along 2D random rough surfaces. The point of the present method is to discretize not only rough surface but also ray tracing. The former helps saving computer memories and the latter does simplifying ray searching algorithm resulting in saving computation time. Numerical calculations are carried out for 2D random rough surfaces, and electric field distributions are shown to check the effectiveness of the proposed DRTM.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.5A
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• pp.397-401
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• 2005

A different alternative method for simulating bit error rate(BER) performance of Satellite Digital Multimedia Broadcasting(DMB) in tunnel environments is presented. The method based on a channel model obtained by ray-tracing is able to support BER estimation over the channel presents arbitrary statistics that are difficult to fit to an analytic expression. The BER performance for System E over the tunnel fading channel that obtained by ray-tracing is predicted by the monte-carlo method. It can be observed that the BER performance for a straight tunnel channel is better than that for a line-of-sight(LOS) area in curved tunnel. Also, the BER performance for LOS areas in a curved tunnel outperforms that for non-line-of-sight(NLOS) areas in a curved tunnel. The BER performances for straight, curved LOS and curved NLOS tunnel channels are better than that for a Rayleigh channel(K=0) and less than that for a Rician channel with K=3. Moreover, for BER=10-3, it can be seen that there is approximately a $1{\sim}1.5\;dB$ difference between those three types of tunnel channels and a Rayleigh channel.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.10C
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• pp.921-926
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• 2006

The Presence of a line-of-sight(LoS) blockage can degrade the UWB positioning accuracy for two reasons. Firstly, it makes estimation of the time of arrival(ToA) of the direct path signal difficult by complicating the multipath structure of the propagation channel. Secondly, the higher dielectric constant of the LoS blocking material than that of free space introduces excess propagation delay which will bias the range estimation. In this paper, methods based on ray tracing to reduce the ranging error resulting from the second reason are Posed. We take two different approaches; a statistical approach and a map-aided method. In the statistical approach, we establish a conditional distribution of the excess propagation delay caused by LoS blockages using a ray tracing technique. The lo6wer bound of the ranging performance based on this model is estimated. Ine ray tracing method is also used for the map-aided ToA positioning approach. UWB propagation measurement data taken in an office environment is used to examine the performance of this method.

• The Journal of the Acoustical Society of Korea
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• v.20 no.3E
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• pp.10-17
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• 2001

The possibility is investigated of determining the diffuse absorption coefficients of the wall surfaces in a real room by minimizing the errors between the measured energy impulse response of a real room and the predicted energy impulse responses obtained from the ray tracing simulation of the room. In other words, this can possibly serve as a basis for "acoustical system identification" in attempting to determine the "best fit" of modelled absorption coefficients to measured energy response data. Algorithms for attempting this were investigated. The algorithms developed for this purpose proved to be rigorous and efficient. Instead of using the ray tracing model to determine the absorption coefficients, the phase image model was used in order to determine the acoustic impedances of wall surfaces. However, the numerical algorithms could not find the correct impedance values, primarily due to the wide range of the acoustic impedance values of any single acoustic material and very long computation time.

• Journal of the korean Society of Automotive Engineers
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• v.15 no.3
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• pp.89-95
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• 1993

This paper presents the development of CAD system for the design of lens of the Turn Signal Lamp that can model and simulate its optical performance. The system consists of three main modules: skin surface modeling module, inner lens modeling module and optical performance simulation module. Skin surface geometry can be modeled by the input of data file and inner lens can be modeled by the input of only four parameter using its geometric characteristics. Also light distribution pattern, the barometer of optical performance is generated by means of finite ray tracing method. The system display modeled geometry, ray tracing and generated light distribution pattern.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.52-55
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• 2002

In this research, the modification method of spherical aberration, and aspherical lens shape design method were investigated. Spherical aberration affects lens's performance directly. Many studies have attempted to remove spherical aberration with a lot of methods in order to reduce the bad effect of spherical aberration. The approach to lens shape design was base on the ray tracing method. From the result, it was confirmed that ray reverse-tracing method was convenient to remove spherical aberration, and could be used very effectively and usefully for aberration-free aspherical lens design.

• Proceedings of the KAIS Fall Conference
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• 2010.11a
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• pp.363-366
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• 2010

본 논문에서는 원형구조의 전파환경을 위한 경로손실을 다각형모델링과 수학적 모델링을 통해 분석하였다. 원형의 통신환경은 비교적 좁은 반경에 곡률이 거의 없고, 내부는 공기저항을 고려한 감압상태로 Ray-tracing 기법은 원형이라는 구조적 특징을 완벽히 적용하는데 문제가 있기 때문에 원에 가까운 다각형을 모델링하였다. 다각형 모델링 방법와 수학적 방법의 전파손실분석결과 반사횟수와 관계없이 유사한 전파손실성능을 확인하였다. 본 논문은 무선을 이용한 튜브 즉, 원형의 철도운영환경도 고려되고 있는 시점에서, 기존의 철도환경과 다른 환경에 대한 무선환경분석을 위한 기초자료로 사용될 수 있을 것이다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.1043-1047
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• 2007

Community Noise has been great concerned in public. Especially, the road traffic noise has affected too much damage on quiet living environment. In this paper, the noise barrier and reducer effect on the street has been analyzed by using the ray tracing method. The outcome of the analysis has been compared to the measurement at the street near the highway. It turns out that noise barrier and reducer decreases noise level by 7dB(A).

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.7 no.1
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• pp.15-25
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• 1996

This paper proposes the modified image method scheme to search the reflected points and the method to calculate the number of rays. These methods are applied to the ray tracing technique for received power and delay profile prediction in microcelular environment. With ray tracing model using these methods, we show the simulated results for various environmental structures. To demonstrate the validity of this approach, these simulated results are compared and analysed with measured results in apartment towns along the street. In addition we proposed the optimum number of multipath rays with the results in microcellular environment.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.727-732
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• 2014

The goal is to find the position of the sound source with the TRM at reflections and refractions environment. The Fermat's principle applied to the ray tracing method are expected to follow the acoustic path in order to obtain acoustic distance and transmittance to. Utilizing them in the TRM was confirmed rear reflectance affect on estimated position, resolution and side lobe. And the TRM performance were superior to one of the beam forming techniques.