• Journal of Biomedical Engineering Research
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• v.20 no.2
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• pp.139-148
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• 1999

In this paper, we designed the dental surgery system based on PC. This system predict post operated 3-dimensional image, So the patient has no need to take CT after surgery and expose his body to radiological damage. We predict the post operated skull from the patient's CT with pre and post cephalometry X-ray. Our novel procedures, to register X-ray and CT, are based on anatomical landmarks, singular value decomposition. And we display the predicted image 3-dimensionally by surface rendering. We verified this system by dry skull experiment and clinical experiment. When significance level is 0.05, there is on significance.

• Journal of KIISE:Computer Systems and Theory
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• v.33 no.1_2
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• pp.128-136
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• 2006

The stippling techniques, which represent objects with numerous points using pen and ink. The previous stippling techniques for Non-Photorsealistc Rendering(NPR) use single-colored points to represent the tone of gray image ur the material of surface. This paper presents a new stippling technique with various colored points based on the analysis of color information. By using the color information of the input image on HSV model, we define the color weight function that allows to determine automatically the number and size of points. The color jittering based on Munsell's color model can generate stippling drawings using various colored points to represent the image. Our color stippling method is expected to be used in many areas such as animation, digital art, video processing and CG tool.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.161-162
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• 1997

It is very useful to perform the surgery simulation before implanting TAH(Total Artificial Heart} in a patient. The space of chest and the shape of vessels are different from patient to patient. So, It is desirable to customize a TAH design to the anatomy structure of a patient. Several studies are performed to visualize and explain the 3D structure of heart. These studies are performed using 2-dimensional ref or mated images and simple measurement. Anatomy structure of a human heart is not so simple. It is 4dimensional structure ; 3-dimensional plus time, heart beating. 3-dimensional reconstruction schemes of medical images developed for about 10 years are usually categorized into two types of rendering technique ; surface rendering and volume rendering. Volume rendering is preferable in medical image processing field because this technique can be applied without considering the complexity of geometry and change of field of interest. The usable space in the chest of patient can be measured by 3D volume matching of patient trunk and TAH model. This space changes with time. In this research we have developed the 4-dimensional volume match program of patient and TAH model. 3-dimensional rendered set of volumes along time were used to simulate TAH fitting trial. The quantitative measurement from this simulation could be applied to customize TAH design.

• Journal of the Korean Society of Radiology
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• v.1 no.2
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• pp.23-30
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• 2007

This paper presents a method of generating 3-dimensional images by preprocessing 2-dimensional abdominal images obtained using CT (computed tomography) and MRI (magnetic resonance imaging) through segmentation, threshold technique, etc. and apply the method to virtual endoscopy. Three-dimensional images were visualized using indirect volume rendering, which can render at high speed using a general-purpose graphic accelerator used in personal computers. The algorithm used in the rendering is Marching Cubes, which has only a small volume of calculation. In addition, we suggested a method of producing 3-dimensional images in VRML (virtual reality modeling language) running on the Web browser without a workstation or an exclusive program. The number of nodes, the number of triangles and the size of a 3-dimensional image file from CT were 85,367, 174,150 and 10,124, respectively, and those from MRI were 34,029, 67,824 and 3,804, respectively.

• 한국HCI학회:학술대회논문집
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• 2006.02a
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• pp.878-883
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• 2006

반투명 물체(Translucent Object)는 불투명한 물체와는 달리 물체 내부에서 산란이 일어난다. 반투명 물체의 한 표면(Surface)을 렌더링하기 위해서는 그 표면의 정규 벡터뿐만 아니라 그 표면의 주변 기하 정보가 필요하다. 그러나 그래픽 하드웨어 구조는 반투명 물체의 실시간 렌더링의 구현에 많은 제약을 준다. 3D 기하 정보 대신에 라디언스 맵(Radiance map)과 깊이 맵(Depth map)과 같은 투영 영상(Projected Image)을 기반으로 하는 영상 공간 접근 방법(Image Space Approach)을 사용함으로써 GPU 상에서 반투명 재질을 실시간으로 표현할 수 있다. 본 논문에서는 영상 공간 접근 방법(Image Space Approach)의 연장선에서 시점을 달리한 여러 장의 투영 영상을 이용함으로써 기존의 한 장의 투영 영상만을 이용한 방법이 가지고 있는 가시성 한계점을 해결한다. 또한 복수 투영 영상의 이용에 따른 계산량 증가에 의해서 손실된 프레임 속도(Frame Rate)에 대해 분석한다.

• Journal of the Korean Society of Visualization
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• v.1 no.2
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• pp.58-70
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• 2003

Meteorological data contains observation and numerical weather prediction model output data. The computerized analysis and visualization of meteorological data often requires very high computing capability due to the large size and complex structure of the data. Because the meteorological data is frequently formed in multi-variables, 3-dimensional and time-series form, it is very important to visualize and analyze the data in 3D spatial domain in order to get more understanding about the meteorological phenomena. In this research, we developed interactive 3-dimensional visualization techniques for visualizing meteorological data on a PC environment such as volume rendering, iso-surface rendering or stream line. The visualization techniques developed in this research are expected to be effectively used as basic technologies not only for deeper understanding and more exact prediction about meteorological environments but also for scientific and spatial data visualization research in any field from which three dimensional data comes out such as oceanography, earth science, and aeronautical engineering.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1999.04a
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• pp.105-107
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• 1999

본 연구의 목적은 CT장비로부터 얻어지는 단면 영상을 이용하여 재구성한 3차원 Voxel 정보를 기반으로 의료 시술 중 위험도가 높으며 장기간의 수술 훈련이 필요한 수술인 척추경나사 삽입술에 대한 모의 시술기를 개발하는 것이다. 모의 시술기의 입력은 환자의 환부에 대한 CT와 모의 시술을 해보고자 하는 의사 (사용자)의 입력 (경나사의 진입 위치와 각도)이 되며 출력은 의사들이 시술장에서 받을 수 있는 유일한 방법인 Voxel데이터로부터 재생성된 X-Ray이미지, 혹은 C-Arm의 동영상이며, 최종 결과 출력은 나사못이 삽입된 재구성 CT 이미지들과 3차원 정보를 볼 수 있는 Image Based Rendering의 Image data set이 된다. 본 연구에서는 각 시각화 부분의 특성을 고려하여 direct volume projection, surface modeling, 그리고 최근 많은 관심을 받고 있는 Image Based Rendering 기법을 intergrate하여 사용하였으며 각 시각화 모듈의 초고속 정보 통신망에서의 정보 교환에 대한 방법론에 대해 다루고 있다.

• Proceedings of the Korea Multimedia Society Conference
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• 2004.05a
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• pp.183-186
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• 2004

2차원 영상 기반의 세포 분석은 2차원 평면 상에서의 관찰만 가능하므로 정확하고 객관적인 분석에 한계가 있다. 따라서 이러한 한계를 극복하고자 컨포컬 현미경을 통해 획득한 연속적인 2차원 단면 영상들로 구성된 볼륨 데이터를 볼륨 및 표면 렌더링을 통해 가시화 하여, 세포핵에 대한 다양한 각도에서의 형태 관찰이 가능하도록 하였다. 또한 세포핵 볼륨에서 ROI 추출을 통해 국부 영역 분석의 효율성을 높였다. 그리고 이 결과를 바탕으로 정확한 암 세포의 계측 및 정량적 분석을 통해 이후 자궁암 환자에게 최적의 진단 및 지료를 제공할 수 있는 연구 기반을 마련하고자 한다.

• Journal of the Korea Computer Graphics Society
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• v.16 no.3
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• pp.1-10
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• 2010

In this paper, we propose a novel noiseless method of BRDF rendering on a GPU in real-time. Illumination at a surface point is formulated as an integral of BRDF producted with incident radiance over the hemi-sphere domain. The most popular method to compute the integral is the Monte Carlo method, which needs a large number of samples to achieve good image quality. But, it leads to increase of rendering time. Otherwise, a small number of sample points cause serious image noise. The main contribution of our work is a new importance sampling scheme producing a set of incoming ray samples varying continuously with respect to the eye ray. An incoming ray is importance-based sampled at different latitude angles of the eye ray, and then the ray samples are linearly connected to form a curve, called a thread. These threads give continuously moving incident rays for eye ray change, so they do not make image noise. Since even a small number of threads can achieve a plausible quality and also can be precomputed before rendering, they enable real-time BRDF rendering on the GPU.

• Journal of KIISE
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• v.43 no.4
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• pp.419-429
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• 2016

Generating a 3D surface model from coronary artery segmentation helps to not only improve the rendering efficiency but also the diagnostic accuracy by providing physiological informations such as fractional flow reserve using computational fluid dynamics (CFD). This paper proposes a method to generate a triangular surface mesh using vessel structure information acquired with coronary artery segmentation. The marching cube algorithm is a typical method for generating a triangular surface mesh from a segmentation result as bit mask. But it is difficult for methods based on marching cube algorithm to express the lumen of thin, small and winding vessels because the algorithm only works in a three-dimensional (3D) discrete space. The proposed method generates a more accurate triangular surface mesh for each singular vessel using vessel centerlines, normal vectors and lumen diameters estimated during the process of coronary artery segmentation as the input. Then, the meshes that are overlapped due to branching are processed by mesh merging and merged into a coronary mesh.