• Journal of the Korea Institute of Military Science and Technology
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• v.21 no.6
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• pp.752-759
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• 2018

The SBR technique is one of the asymptotic high frequency method, where a dense grid of rays are launched and traced to analyze the scattering properties of the target. In this paper, we propose an accelerated SBR technique using grouping a central ray and 8 surrounding rays around the center ray. First, launched rays are grouped into groups consisting of a central ray and 8 surrounding rays. After the central ray of each group is preferentially traced, 8 surrounding rays are rapidly traced using the information of ray tracing for the central ray. Simulation result of scattering analysis for CAD models verifies that the proposed method reduces the computational time without decreasing the accuracy.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.6 s.99
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• pp.635-644
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• 2005

This paper is. a study on relation between road traffic noise(RTN) and sound power level(PWL). At present, many experimental formulae and prediction formulae are used for prediction of RTN. But these formulae are difficult to appiy to the metropolitan area because these formulae are inaccurate in the different condition from reference condition. This paper calculate RTN and PWL of each prediction formula, choose the best one and make a noise map of the subject area. Procedure is as follows. First, calculate $L_{eq}$ of RTN using experimental formulae and prediction formulae. Second, calculate PWL using $L_{eq}$ of RTN and distance attenuation for point source at semi-free field. Third, choose the most accurate formula. And finally, make a noise map of the subject area at present and future. The result using noise map will be able to apply to application field. Noise mapping tool used on this paper is Raynoise program using Ray Tracing Method(RTM), Mirror Image Source Method(MISM) and Hybrid Method(HM).

• Journal of the Korea Computer Graphics Society
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• v.14 no.3
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• pp.31-46
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• 2008

The depth of field is the range that the objects inside of this range treated to be focused. Objects that are placed out of this range are out of focus and become blurred. In computer graphics, generating depth of field effects gives a great reality to rendered images. The previous researches on the depth of field in computer graphics can be divided into two major categories. One of them is the distributed ray tracing that samples the lens area against each pixel. It is possible to obtain precise results without noise if enough number of samples are taken. However, to make a good result, a great number of samples are needed, resulting in an enormous timing requirement. The other approach is the method that approximates depth of field effect by post-processing an image and its depth values computed using a pin-hole camera. Though the second technique is not that physically correct like distributed ray tracing, many approaches which using this idea have been introduced because it is much faster than the first approach. But the post-processing have some limitations because of the lack of ray information. In this paper, we first present an improvement technique that corrects the previous post-processing methods and then propose another one that accelerates the distributed ray tracing by using a radiance caching method.

• Journal of the Korea Computer Graphics Society
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• v.29 no.3
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• pp.93-103
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• 2023

The problem of reconstructing three-dimensional models of people and objects from color and depth images captured by low-cost RGB-D cameras has long been an active research area in computer graphics. Color and depth images captured by low-cost RGB-D cameras are represented as point clouds in three-dimensional space, which correspond to discrete values in a continuous three-dimensional space and require additional surface reconstruction compared to rendering using polygonal models. In this paper, we propose an effective ray-tracing based technique for visualizing point clouds rather than polygonal models. In particular, our method shows the possibility of an effective rendering method even in mobile environment which has limited performance due to processor heat and lack of battery.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.54-57
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• 2002

In this paper, an adaptive beam tracing method with revised subdivision technique is proposed, in which the beam is generated by a set of three rays. According to reflection and/or refraction of the rays on the buildings and/or ground, additional rays are generated adaptively and the beam is subdivided efficiently and automatically. After generation of the set of beams, we transform the electromagnetic wave propagation data into volume data. Then one can visualize the data of propagation with reflection, refraction and interaction in full three dimensional space at any viewpoint by the so-called ray casting algorithm, which is one of the most useful methods in compute. graphics(CG).

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.379-382
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• 2005

This study proposes an effective algorithm that can render a realistic image of a lighting environment, especially an automotive rear lamp, using the backward ray tracing method. To producea realistic image similar to that perceived by the human eye, the incident light energy at the eye point estimated by a ray tracing algorithm is represented by XYZ tri-stimulus values, which are then converted into RGB values considering the particular display device.

• The Journal of the Acoustical Society of Korea
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• v.14 no.3
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• pp.82-89
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• 1995

A sound field simulator is constructed to obtain the sound field paramaters such as the magnitudes and directions of early reflections with moderate efforts. The proposed simulator is based on the hybrid ray tracing method that traces rays reached the listener position and convert them to image sound sources. By this approach, we can obtain the directional impulse response relatively easily with minimum casts. Simulation experiment results of several performace places are reported to how the versatility of the proposed simulator system.

• Journal of Astronomy and Space Sciences
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• v.23 no.4
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• pp.327-336
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• 2006

In this paper, gain loss of KVN (Korean VLBI Network) 21-m shaped Cassegrain antenna due to misalignment of antenna optics is calculated using ray-tracing method. It enables us to estimate alignment tolerances of feed and sub-reflector positioning. According to numerical results, KVN 21-m shaped Cassegrain antenna's gain loss is more sensitive to positions of feed and sub-reflector than in case of the equivalent classical Cassegrain antenna. The result of calculation is believed to be utilized as a possible guideline when checking the performance of the antenna system.

• Journal of electromagnetic engineering and science
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• v.18 no.3
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• pp.154-159
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• 2018

In this paper, electromagnetic radiation from a slot array antenna enclosed by a Von Karman radome is analyzed by using the ray tracing method and Huygens's principle. We consider the rectangular slot array antenna and the Von Karman radome. The radiation patterns are calculated by using the surface currents of the radome to illustrate the electromagnetic behaviors of the radome-enclosed waveguide slot array antenna.

• Journal of electromagnetic engineering and science
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• v.18 no.4
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• pp.242-247
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• 2018

This paper studies a convenient electromagnetic field (EMF) compliance assessment for base station installations at a millimeter wave (mmW) frequency. We utilize ray-tracing analysis as a numerical method for examining the wave propagation characteristic. Various installation cases are considered and the important parameters with a significant effect on the maximum power density levels are produced. We finally suggest the several scenarios for the convenient assessment of mmW base stations, which allow us to conduct cost effective computational tests compared with the current assessment procedure in the guideline.