• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.5 no.2
• /
• pp.263-268
• /
• 2001

This paper analyzes error probability performance adopted the Ray Tracing method efficiently analyzing millimeter wave or optic wave in Inter Vehicle Communication(IVC). Analysis environment analyzed bit error characteristic in 60㎓ band with very powerful to multipath wave, to be large to oxygen absorption and to be good to frequency reuse efficiency. We analyzed bit error characteristic of DS/CDMA system by multi access user in Two-Ray rician channel adopted reflect wave of grand, reflect wave of concrete wall and reflect wave of driving vehicle at side road. Improvement performance is adopted MRC diversity.

• Nuclear Engineering and Technology
• /
• v.34 no.3
• /
• pp.250-258
• /
• 2002

This Paper is to apply the well-established coarse mesh finite difference(CMFD) method to the method of characteristics(MOC) transport calculation as an acceleration scheme. The CMFD problem is first formulated at the pin-cell level with the multi-group structure To solve the cell- based multi-group CMFD problem efficiently, a two-group CMFD formulation is also derived from the multi-group CMFD formulation. The performance of the CMFD acceleration is examined for three test problems with different sizes including a realistic quarter core PWR problem. The CMFD formulation provides a significant reduction in the number of ray tracings and thus only about 9 ray tracing iterations are enough for the realistic problem. In computing time, the CMFD accelerated case is about two or three times faster than the coarse-mesh rebalancing(CMR) accelerated case.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.26 no.3
• /
• pp.95-104
• /
• 1989

This paper presents a new shadow testing acceleration scheme for ray tracing called Hybrid Shadow Testing (HST) based on a conditional switching between the conventinal shadow testing method and Crow's shadow volume method, where the shadow polygons as well as the object polygons are registered onto the corresponding cells under the 3-D space subdivision environment. Despite the preprocessing time for the generation and registration of the shadow polygons, the total shadow testing time of the proposed algorithm, HST was approximately 50% of that of the conventional shadow testing method for several examples while the total ray tracing time was typically reduced by 30% from the conventional approach. This due to the selective use of the shadow volume method with a compromise between the maximal utilisation of shadow's spatial coherency and minimising the computational overhead for checking ray intersections with the shadow polygons. A parameter, $N_{th}$ denoting the critical number of shadow polygons between successive reflection points was used as a guideline for switching the shadow testing scheme between the conventional method and shadow volume method. A method for calculating $N_{th}$ from such statistical data as the number of object polygons, average polygon size average peripheral length of the polygons was proposed, resulting in good agreement with the experimental results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.15 no.8
• /
• pp.759-764
• /
• 2004

This paper proposes a method that estimates MIMO channel characteristics analytically using a 3D ray tracing propagation model. We calculate the discrete spatial correlation between sub-channels by considering phase differences of paths, and using this, estimate the mean capacity upper bound of MIMO channel by Jensen's inequality. This analysis model is a deterministic model that do not approach stochastically through measurement nor approach statistically through Monte-Carlo simulations, so this model has high efficiency for time and cost. And based on the electromagnetic theory, this model may analyze quantitatively the parameters which can affect the channel capacity - antenna pattern, polarization mutual coupling, antenna structure and etc. This model may be used for the development of an optimal antenna structure for MIMO systems.

• Journal of the Korea Computer Graphics Society
• /
• v.23 no.3
• /
• pp.123-133
• /
• 2017

Cache performance is an important factor in hardware system. We proceed with a cache simulation to analyze the cache performance suitable for sound rendering. In addition, we introduce hardware models based on ray tracing used in geometric method and studies to improve cache performance. Cache simulation is performed on various conditions for cache size, way and block. Various simulations can be found to influence the cache hit rate. We compare cache simulation results with actual hardware performance to analyze cache performance suitable for sound rendering.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.59 no.6
• /
• pp.1114-1119
• /
• 2010

This paper is concerned with an numerical analysis of electromagnetic wave propagation from randomly rough surfaces as a desert, sea surface and so on. We propose discrete ray tracing method (DRTM) for analysis of characteristics of wave propagation along one dimensional (1D) and two dimensional (2D) random rough surfaces. The point of the present method is to discretize not only rough surface but also ray tracing. This technique helps saving computer memories and does simplifying ray searching algorithm resulting in saving computation time. Numerical calculations are carried out for 1D and 2D random rough surfaces and electric field distributions are shown to check the effectiveness of the proposed DRTM.

• 한국전산유체공학회:학술대회논문집
• /
• 2011.05a
• /
• pp.173-178
• /
• 2011

Nowadays, SELENE-2 is under development for the moon explorer rover in Japan. AXS(Active X-ray Spectrometer) sensor development among the candidated payloads will be on going by the world-wide co-operation. The thermal design, analysis and test will be specially performed by Korean institutes. CFD techniques are used for the conceptual design and analysis. Thin-shell plate meshes being applied by Monte-Carlo Ray Tracing Method are generated for the thermal radiation analysis. Lumped capacity model is employed for the thermal conduction simulation of the AXS payload itself. Various shapes of the payload configuration with thermal boundary conditions are proposed and selected on the purpose of the analysis of the initial design. The results of the analysis are supposed to be used as the baseline for the further detailed design of the AXS payload in the future.

• ETRI Journal
• /
• v.28 no.2
• /
• pp.247-249
• /
• 2006

In the development of a new wireless communications system, a versatile and accurate radio channel for indoor communications is needed. In particular, the investigation of radio transmission into buildings is very important. In this letter, we present an improved three-dimensional electromagnetic wave propagation prediction model for indoor wireless communications that takes into consideration building penetration loss. A ray tracing technique based on an image method is also employed in this study. Three-dimensional models can predict any complex indoor environment composed of arbitrarily shaped walls. A speed-up algorithm, which is a modified deterministic ray tube method, is also introduced for efficient prediction and computation.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.30 no.5
• /
• pp.217-222
• /
• 2018

An analytical method for determining the degree of wave refraction is investigated. The ray tracing method previously used to calculate wave propagating cannot explain the degree of refraction caused by different kinds of conditions. In this study, we suggest the index of refraction degree using the principle that refraction is caused by the difference of phase velocities along the crest line.

• Journal of electromagnetic engineering and science
• /
• v.1 no.1
• /
• pp.48-53
• /
• 2001

This paper presents a new 3-D ray tracing technique based on the image theory with newly defined ray tubes. The proposed method can be applied to indoor environments with arbitrary building layouts and has high computational efficiency compared to the precedent methods resorting to the ray launching scheme. It predictions are in good agreement with the measurements.