• 천문학회보
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• 제39권2호
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• pp.86.2-86.2
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• 2014

We present a new ray-tracing code, "Odyssey", for the Kerr spacetime accelerated by the Graphics Processing Unit (GPU). Taking advantage of the ability of nVidia graphic cards to evaluate trajectories of a large amount of photon simultaneously, the code is two orders of magnitude as fast as the previous CPU-based code corresponding to the speed of few nanoseconds per photon per time step. In the light of the Graphic User Interface (GUI) powered by the GPU-enhanced 2D/3D displaying technique, DirectX, it is feasible for users to manipulate diverse results such as rotating and zooming in/out the trajectories of photon instantly near the black hole. Thus the Odyssey can serve as a tool not only for scientific but also for the educational purpose. We discuss possible applications in detail in light of several results such as the shape of the silhouette of a black hole, the shape of a hot spot orbiting a black hole, and 3D photon trajectories.

• 한국전자파학회논문지
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• 제10권5호
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• pp.766-776
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• 1999

본 논문에서는 실내 전파 환경에서의 편파 다이버시티와 공간 다이버시티의 성능을 분석하기 위하여 영상 법을 기본으로 한 3차원 광선 추적법을 이용하였다. 본 모텔링은 선호강도 뿐만 아니라 채널의 페이딩 특성 을 예측할 수 있기 때문에 편파 및 공간 다이버시티 기법의 성능을 분석하는데 이용될 수 있다. 측정과 시율 레이션 결과로부터 편파 및 공간 다이버시티가 실내 무선 통선 채널의 성능을 향상시킬 수 있음을 확인하였 고, 특히 지향성 안테나를 이용한 편파 다이버시티를 제안하여 기존의 다이폴 안테나를 이용하는 다이버시티 기볍보다 우수한 성능을 가짐을 보였다.

• 한국게임학회 논문지
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• 제17권1호
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• pp.7-16
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• 2017

3D 게임그래픽 표현기술은 게임콘텐츠발전과 함께 콘텐츠 분야에서 중요한 요소가 되었다. 특히 게임 캐릭터 표현 기술은 사실적인 그래픽 기술과 시각적인 즐거움을 주는 것 이외에 게임을 진행하는 게임에 대한 몰입도의 중간 단계역할을 하며 플레이어가 마치 게임 속에서 영웅적인 모험을 즐길 수 있도록 착각을 만들어 낸다. 3D 게임에 있어서 게임캐릭터의 높은 완성도는 개발과정 가운데 캐릭터 설정작업의 세심한 디테일작업과 신중함이 주요요인으로 작용한다[3]. 본 논문에서는 게임구현을 위하여 인지적 AI 알고리즘이 적용된 3D 유니티 게임 엔진을 사용하여 radiosity의 수학적인 모델과 기본적인 radiosity 모델, 점진적 개선 radiosity 모델 기법을 방법론을 소개하고, 모바일 게임에 적용한 캐릭터 표현기법을 제안하려고 한다. 게임엔진에 실제적으로 적용하여보니 렌더링과정과 모의실험에서 표면의 투영도는 게임콘텐츠 환경의 조명도에 따라 변화됨을 발견 할 수 있어서, 전체적으로 질 높은 게임캐릭터가 완성되었음이 확인 되었다.

• 대한전자공학회논문지
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• 제26권3호
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• pp.95-104
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• 1989

본 논문은 3차원적 분할공간 환경에서 종래의 음영검사법과 Crow의 음영입체법을 상황에 따라 우리하도록 선택하는 혼합음영검사법을 소개하고 파라메타화를 통하여 그 선택의 최적화를 꾀하였다. 추가적인 선행계산시간이 소요됨에도 불구하고 제안된 혼합음영검사법은 여러가지 예제화면들에 재하여 종래의 방법에 비하여 음영계산시간에 있어서는 50%, 전체묘화시간에 있어서는 30%정도씩의 CPU시간단축효과를 보였다. 그 원인은 음영검사의 선택적 사용을 통하여 그림자영역의 일관성(coherency)을 이용한데에 있다. 연속되는 두 반사점사이에 존재하는 음영다각형의 갯수를 나타내는 $N_{th}$라는 파라메타가 음영검사의 효과적 선택을 위한 지표가 되며, 묘화환경의 통계적 수치로부터 이 값을 알아내는 방법이 제안되고 실험적 결과와 비교된다.

• 한국멀티미디어학회논문지
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• 제7권12호
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• pp.1729-1736
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• 2004

This paper proposes an efficient collision detection method in the dynamic spatial subdivisions for the MMORPG engine which requires realtime interactions. An octree is a suitable structure for static scenes or terrain processing. An octree spatial subdivision enhances rendering speed of scenes. Current spatial subdivisions tend to be highly optimized for efficient traversal, but are difficult to update quickly for a changing geometry. When an object moves to the outside extent for the spatial subdivisions, the acceleration structure would normally have to be rebuilt. The OSP based on a tree is used to divide dynamically wide outside which is the subject of 3D MMORPG. TBV does not reconstruct all tree nodes of OSP and has reduced rebuilding times by TBV information of a target node. A collision detection is restricted to those objects contained in the visibility range of sight by using the information established in TBV. We applied the HBV and ray tracing for an efficient collision detection.

• Journal of the Optical Society of Korea
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• 제18권4호
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• pp.370-376
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• 2014

We optimized the design of the flat encapsulant of a light-emitting diode (LED) package to obtain higher light output power (LOP), both by experiment and simulation using three-dimensional ray-tracing software. In the experiment, the refractive index of the encapsulant was varied (1.41 and 1.53). In addition, double-layer structures with these refractive indices (1.41/1.53) were investigated by varying the shape of the interface between the two among flat, concave, and convex. The experiments showed that the LOP of the double-layer encapsulant with convex interface increased by 13.4% compared to the single-layer encapsulant with a refractive index 1.41, which was explained by the increase of the light extraction efficiency (LEE) in connection with the increase of the critical angle (${\theta}_c$) and the decrease of the Fresnel reflection.

• ETRI Journal
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• 제45권4호
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• pp.557-569
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• 2023

Traditional deterministic channel modeling is accurate in prediction, but due to its complexity, improving computational efficiency remains a challenge. In an alternative approach, we investigated a multilayer artificial neural network (ANN) to predict large-scale and small-scale channel characteristics in metro tunnels. Simulated high-precision training datasets were obtained by combining measurement campaign with a ray tracing (RT) method in a metro tunnel. Performance on the training data was used to determine the number of hidden layers and neurons of the multilayer ANN. The proposed multilayer ANN performed efficiently (10 s for training; 0.19 ms for prediction), and accurately, with better approximation of the RT data than the single-layer ANN. The root mean square errors (RMSE) of path loss (2.82 dB), root mean square delay spread (0.61 ns), azimuth angle spread (3.06°), and elevation angle spread (1.22°) were impressive. These results demonstrate the superior computing efficiency and model complexity of ANNs.

• 대한전자공학회논문지
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• 제25권12호
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• pp.1633-1638
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• 1988

This paper proposes the lattice-structured space subdivision method using bounding volume to reduce a great number of ray-surface intersection calculations in ray tracing algorithm for the computer graphics. We show that this method reduced 50%-70% calculations compard to pre-exist method by experiments.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2008년도 한국우주과학회보 제17권2호
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• pp.28.1-28.1
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• 2008

Detection of spectral bio-signatures from extra terrestrial planets has received an increasing attention from the astronomy and space science communities in recent years. In an attempt to better-understand disk averaged spectra of the only know terrestrial planet i.e. Earth, we are constructing a scale-able 3D earth model with surface reflectance and scattering properties. The USGS coastal line data were used to form coastal line segments and they were then stitched to generate continuous coastal lines to represent major continents and large islands. As the first stage of model verification, wavelength dependent ocean and land reflectance data and scattering characteristics were defined over the land and sea surfaces respectively. We then performed ray tracing based imaging and radiometric transfer simulations using a hypothetical optical payload receiving the reflected and scattered sun lights from the earth. The model concept, computational details, the simulation results are discussed as well as the future development plan.

• 대한의용생체공학회:의공학회지
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• 제12권2호
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• pp.79-88
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• 1991

Semi-transparent volume rendering technique can provide 3-D visualization well by voxel level Processing and alleviate segmentation arf, ifacts compared wish the surface rendering technique. In this Paper, we consider several new schemes which can improve she Perform ance of volume rendering. A directional interpolation method is proposed to reduce the artifact due to the anisotrophic resolution in X-ray CT data. The computation time for rendering is shortened by using the depth information of the 3-D object. And also, we reduce the quantization artifacts in the rendering by introducing the opacity-dependent sampling interval to sampling in ray-tracing.