• Journal of the Korea Computer Graphics Society
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• v.2 no.1
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• pp.1-6
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• 1996

In ray tracing of 3D volume data, the color of each pixel in the image is typically obtained by accumulating the contributions of sample points on the ray cast from the pixel point. This accumulation is most naturally represented by integration. In most methods, however, it is done by numerical summation because analytical solution to the integration are hard to find. This paper shows that a semi-analytical solution can be obtained for a typical ray tracing of volume data. Tentative conclusions about the significance and usefulness of our approach are presented based on our experiments.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.108.1-108.1
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• 2012

Previously we introduced ray-tracing based 3D optical earth system model for specular and scattering properties of all components of the system (i.e. clear-sky atmosphere, land surfaces and an ocean surface). In this study, we enhanced 3-dimensional atmospheric structure with vertical atmospheric profiles for multiple layer and cloud layers using Lambertian and Mie theory. Then the phase dependent disk averaged spectra are calculated. The main results, simulated phase dependent disk averaged spectra and light curves, are compared with the 7 bands(300~1000nm) light curves data of the Earth obtained from High Resolution Instrument(HRI) in Deep Impact spacecraft during Earth flyby in 2008. We note that the results are comparable with the observation.

• Korean Journal of Optics and Photonics
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• v.16 no.3
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• pp.201-208
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• 2005

In order to realize a 3-D stereoscopic display module with alternating illumination angles, several conditions required for a lenticular lens sheet were established, and then both the lens specification and the module structure were designed. Also the performance of the stereoscopic module and its tolerance characteristics were evaluated by simulating the intensity distribution on the observation plane with a finite-ray tracing technique. From the evaluation, it was known that an intersection area between two adjacent lenses should not be filled and that the lateral mismatch between a planar liquid crystal shutter and a lens sheet should be minimized.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.4
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• pp.43-48
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• 2015

A focal length-correcting lens called the F-theta lens is required to compensate for the different focus on spot size due to the deflected incident laser beam. The F-theta lens was designed by the ray tracing method and fabricated by a 3D printer with polymer-based material. The designed F-theta lens is able to compensate for the focus on spot size by an incidence angle of 0 to 2 degrees. Based on the analysis of the simulation, there was almost no aberration in the $0^{\circ}C$ incidence angle, and the maximum of $50{\mu}m$ of aberration was observed at the incidence angle of $2^{\circ}$. Diffraction-encircled energy was analyzed to characterize the designed optics, and an image simulation was performed to confirm the actual image resolution.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2001.11a
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• pp.283-287
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• 2001

본 논문에서는 3D Ray Tracing 편파특성 예측 시뮬레이터를 개발하고 초고속 옥내 무선환경에서의 원형편파 우수성을 시뮬레이션을 통하여 확인하였다. 제안된 3D Ray Tracing 기법을 이용하여 시뮬레이션 한 결과 기수회의 반사파가 수신기에서 수신되지 않는 원형판파의 특성 때문에 다중경로 페이딩을 현저히 감소시킬 수 있음을 확인하였다. 또한, 옥내 가시거리(LOS) 및 비가시거리(NLOS) 환경에서의 원형편파를 이용한 페이딩 경감효과는 수직 및 수평견파나 편파다이버시티보다 우수함을 알 수 있었고, DS-CDMA 시스템을 이용한 경우에 있어서도 원형편파가 보다 우수한 BER 성능을 나타냄을 확인하였다.

• Nuclear Engineering and Technology
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• v.51 no.5
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• pp.1436-1443
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• 2019

A fast gamma-ray dose rate assessment method for complex geometries based on stylized model reconstruction and point-kernel method is proposed in this paper. The complex three-dimensional (3D) geometries are imported as a 3DS format file from 3dsMax software with material and radiometric attributes. Based on 3D stylized model reconstruction of solid mesh, the 3D-geometrical solids are automatically converted into stylized models. In point-kernel calculation, the stylized source models are divided into point kernels and the mean free paths (mfp) are calculated by the intersections between shield stylized models and tracing ray. Compared with MCNP, the proposed method can implement complex 3D geometries visually, and the dose rate calculation is accurate and fast.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.1B
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• pp.114-124
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• 2002

In this paper, we proposed the image-based 3D ray tracing indoor propagation model using a patch scattering model for fading analysis of indoor propagation environments. An image-based 3D ray tracing technique is mainly used, which allows the rapid generation of the complex channel impulse response for any given location and polarization of transmitter and receiver. Due to the site specific nature of indoor environment, we took into account the location and the electrical properties of individual walls and objects such as windows, doors and plaster board in our propagation model. Besides, the 3D radiation beam-patterns and polarizations of arbitrary antennas were considered, and using patch scattering model we can consider the change of the polarization due to the scattering from the various indoor objects, like desks, chairs and etc. the are almost impossible to be modeled with the basic image-based ray tracing method. The model will predict the impulse response, the rms delay spread, the fading characteristics of the channel and performances of the polarization diversity schemes.

• 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.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.1
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• pp.76.2-76.2
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• 2012

The understanding spectral characterization of possible earth-like extra solar planets has generated wide interested in astronomy and space science. The technical central issue in observation of exoplanet is deconvolution of the temporally and disk-averaged spectra of the exoplanets. The earth model based on atmospheric radiative transfer method has been studied in recent years for solutions of characterization of earthlike exoplanet. In this study, we report on the current progress of the new method of 3D earth model as a habitable exoplanet. The computational model has 3 components 1) the sun model, 2) an integrated earth BRDF (Bi-directional Reflectance Distribution Function) model (Atmosphere, Land and Ocean) and 3) instrument model combined in ray tracing computation. The ray characteristics such as radiative power and direction are altered as they experience reflection, refraction, transmission, absorption and scattering from encountering with each all of optical surfaces. The Land BRDF characteristics are defined by the semi-empirical "parametric-kernel-method" from POLDER missions from CNES. The ocean BRDF is defined for sea-ice cap structure and for the sea water optical model, considering sun-glint scattering. The input cloud-free atmosphere model consists of 1 layers with vertical profiles of absorption and aerosol scattering combined Rayleigh scattering and its input characteristics using the NEWS product in NASA data and spectral SMARTS from NREL and 6SV from Vermote E. The trial simulation runs result in phase dependent disk-averaged spectra and light-curves of a virtual exoplanet using 3D earth model.

• Journal of the Korean Solar Energy Society
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• v.31 no.4
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• pp.136-141
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• 2011

The lightshelf system reduces intense illumination levels of indoor from direct sun light and reflect to lead diffused light into indoor deeply. This study aims to design acurved-lightshelf by a ray tracing method and evaluate the daylighting performance of window integrated with the curved-lightshelf by computer simulations. For this purpose, evaluation test model was designed for the experiments to validate the simulation model, and the curved-lightshelf was designed by the ray tracing method using Ecotect. After the office model was designed using 3D simulation, the average indoor illuminance, luminance and distribution of illuminance were evaluated by simulation which has a algorithm of Radiosity and Ray-Tracing method under four different cases(case1;no lightshelf, case2; Flat board, case3; tilted at $30^{\circ}$ angle, case4; the curved-lightshelf). As results, it turns out that case1 showed higher average illuminance and case4 was more uniformly distributed than case2 and case3, In addition average luminance of case1 was also lower. indicating that the curved-lightshelf would reduce the possibility of the glare, while maintaining the sufficient daylight level.