• Proceedings of the Korea Society for Simulation Conference
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• 한국시뮬레이션학회 1999년도 춘계학술대회 논문집
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• pp.143-146
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• 1999

수술 시뮬레이션은 의학 교육, 수술 훈련, 수술 계획과 정확한 수술을 위해 그 중요성이 더해지고 있다. 본 논문은 물리적 모델을 기반으로 3차원 객체의 변형을 인터액티브하게 수행할 수 있는 인체 내장 기관에 대한 수술 시뮬레이터의 개발을 목적으로 한다. 물리적 모델은 컴퓨터 애니매이션과 컴퓨터 그래픽 모델에 대한 새로운 시도로써 많이 연구되고 있으며, 본 논문에서는 심장에 대한 3차원 자료를 매스-스프링 모델로 구현 및 변형을 수행하였다. 본 연구의 결과는 일차적으로는 심장 수술 시뮬레이션에 적용 가능하며 나아가 다른 내장 기관의 수술 시뮬레이션 및 non-rigid한 객체에 대한 변형에 적용 가능하다.

• Journal of Industrial Technology
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• 제18권
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• pp.225-232
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• 1998

Train crashes involve complex interaction between deformable bodies in multiple collisions. The purpose of this study is to suggest the effective analytical procedure using finite element model for the crashworthiness of motorized trailer of high speed train. Various types of crash events are investigated and the conditions for numerical simulation are defined. Finally korean high speed train which consists of aluminum members can be analyzed and designed by the numerical simulation.

• Proceedings of the Optical Society of Korea Conference
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• 한국광학회 2003년도 하계학술발표회
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• pp.156-157
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• 2003

적응광학(AO； adaptive optics) 시스템의 중요한 구성요소인 파면측정 장치(wavefront sensor)는 변형거울(deformable mirror)과 제어용 컴퓨터에 연결되어 파면보정을 실시간으로 처리할 수 있도록 파면의 왜곡정보를 제공한다. 제작된 Shack-Hartmann 파면측정 장치는 배열렌즈(array lens), 빔 축소 광학계, CCD 카메라 등으로 구성되어있는데, 측정된 파면의 정보는 영상처리 보드가 내장된 제어용 컴퓨터를 사용하여 분석한 뒤 실시간으로 보정장치를 구동할 수 있도록 설계되었다. (중략)

• Advances in concrete construction
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• 제15권2호
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• pp.137-147
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• 2023

Dynamic analysis of a shear deformable shell is investigated with accounting thickness stretching using Hamilton's principle. Through this method, the total transverse is composed into bending, shearing and stretching portions, in which the third part is responsible for deformation along the transverse direction. After computation of the strain, kinetic and external energies, the governing motion equations are derived using Hamilton's principle. A comparative study is presented before presentation of full numerical results for confirmation of the formulation and methodology. The results are presented with and without thickness stretching to show importance of the proposed theory in comparison with previous theories without thickness stretching.

• Journal of International Society for Simulation Surgery
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• 제1권1호
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• pp.37-40
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• 2014

Purpose For living donor liver transplantation, liver segmentation is difficult due to the variability of its shape across patients and similarity of the density of neighbor organs such as heart, stomach, kidney, and spleen. In this paper, we propose an automatic segmentation of the liver using multi-planar anatomy and deformable surface model in portal phase of abdominal contrast-enhanced CT images. Method Our method is composed of four main steps. First, the optimal liver volume is extracted by positional information of pelvis and rib and by separating lungs and heart from CT images. Second, anisotropic diffusing filtering and adaptive thresholding are used to segment the initial liver volume. Third, morphological opening and connected component labeling are applied to multiple planes for removing neighbor organs. Finally, deformable surface model and probability summation map are performed to refine a posterior liver surface and missing left robe in previous step. Results All experimental datasets were acquired on ten living donors using a SIEMENS CT system. Each image had a matrix size of $512{\times}512$ pixels with in-plane resolutions ranging from 0.54 to 0.70 mm. The slice spacing was 2.0 mm and the number of images per scan ranged from 136 to 229. For accuracy evaluation, the average symmetric surface distance (ASD) and the volume overlap error (VE) between automatic segmentation and manual segmentation by two radiologists are calculated. The ASD was $0.26{\pm}0.12mm$ for manual1 versus automatic and $0.24{\pm}0.09mm$ for manual2 versus automatic while that of inter-radiologists was $0.23{\pm}0.05mm$. The VE was $0.86{\pm}0.45%$ for manual1 versus automatic and $0.73{\pm}0.33%$ for manaual2 versus automatic while that of inter-radiologist was $0.76{\pm}0.21%$. Conclusion Our method can be used for the liver volumetry for the pre-surgery planning of living donor liver transplantation.

• Structural Engineering and Mechanics
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• 제65권5호
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• pp.621-631
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• 2018

In this paper, an exact analytical solution is developed for the analysis of the post-buckling non-linear response of simply supported deformable symmetric composite beams. For this, a new theory of higher order shear deformation is used for the analysis of composite beams in post-buckling. Unlike any other shear deformation beam theories, the number of functions unknown in the present theory is only two as the Euler-Bernoulli beam theory, while three unknowns are needed in the case of the other beam theories. The theory presents a parabolic distribution of transverse shear stresses, which satisfies the nullity conditions on both sides of the beam without a shear correction factor. The shear effect has a significant contribution to buckling and post-buckling behaviour. The results of this analysis show that classical and first-order theories underestimate the amplitude of the buckling whereas all the theories considered in this study give results very close to the static response of post-buckling. The numerical results obtained with the novel theory are not only much more accurate than those obtained using the Euler-Bernoulli theory but are almost comparable to those obtained using higher order theories, Accuracy and effectiveness of the current theory.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• 제9권4호
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• pp.323-329
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• 2016

This paper describes an insole FFO(Functional Foot Orthosis) model for comfortable walking by considering weight distribution. There are many ways to make an insole FFO model such as using 3D computer graphics, or plaster manually. Thus, we proposed a standardized way to make an insole model, specifically called, robust and automatically personalized deformable insole model. Our proposed method showed 0.8cm average error compared between our proposed auto-deformable insole model and the other insole model manually deformed by experts. Therefore, our proposed method can be an efficient way to make a customized insole model with small error compared to the manually customized insole model.

• 한국HCI학회:학술대회논문집
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• 한국HCI학회 2008년도 학술대회 1부
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• pp.39-44
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• 2008

This paper proposes a real-time geometric correction system based on a projector to project digital images onto deformable surface. Markers use to trace lots of corresponding points would spoil the projected image when the projector projects a digital image onto the surface because they leave marks on the surface. In addition, it is difficult to build a real-time geometric correction system since bottlenecks occur through the process of the geometric correction for projecting images. In this paper, we use invisible infrared markers and a vertex shader of GPU using Cg TookKit of NVIDIA in order to eliminate disadvantage and bottlenecks in the process of markers recognition so that it is possible to project natural correction images in real-time. As a result, this system overlays an interactive virtual texture onto the real paper by using the geometric transformation. Therefore, it is possible to develop variation of AR(Augmented Reality) based on digital contents systems.

• Korean Journal of Computational Design and Engineering
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• 제17권5호
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• pp.303-311
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• 2012

Laparoscopic surgery is a surgical procedure which uses long laparoscopic instruments through tiny holes in abdomen while watching images from a laparoscopic camera through umbilicus. Laparoscopic surgeries have many advantages rather than open surgeries, however it is hard to learn the surgical skills for laparoscopic surgery. Recently, some virtual simulation systems for laparoscopic surgery are developed to train novice surgeons or resident surgeons. In this study, we introduce the techniques that we developed for laparoscopic surgical training simulator for cholecystectomy (gallbladder removal), which is one of the most frequently performed by laparoscopic surgery. The techniques for cholecystectomy simulation include modeling of human organs (liver, gallbladder, bile ducts, etc.), real-time deformable body calculation, realistic 3D visualization of surgical scene, high-fidelity haptic rendering and haptic device technology, and so on. We propose each simulation technique for the laparoscopic cholecystectomy procedures such as identifying cystic duct and cystic artery to clamp and cut, dissecting connective tissues between the gallbladder and liver. In this paper, we describe the techniques and discuss about the results of the proposed cholecystectomy simulation for laparoscopic surgical training.

• Journal of the Korea Society of Computer and Information
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• 제21권10호
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• pp.11-19
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• 2016

The size of a display is large, The form becoming various of that do not apply to previous methods of gaze tracking and if setup gaze-track-camera above display, can solve the problem of size or height of display. However, This method can not use of infrared illumination information of reflected cornea using previous methods. In this paper, Robust pupil detecting method for eye's occlusion, corner point of inner eye and center of pupil, and using the face pose information proposes a method for calculating the simply position of the gaze. In the proposed method, capture the frame for gaze tracking that according to position of person transform camera mode of wide or narrow angle. If detect the face exist in field of view(FOV) in wide mode of camera, transform narrow mode of camera calculating position of face. The frame captured in narrow mode of camera include gaze direction information of person in long distance. The method for calculating the gaze direction consist of face pose estimation and gaze direction calculating step. Face pose estimation is estimated by mapping between feature point of detected face and 3D model. To calculate gaze direction the first, perform ellipse detect using splitting from iris edge information of pupil and if occlusion of pupil, estimate position of pupil with deformable template. Then using center of pupil and corner point of inner eye, face pose information calculate gaze position at display. In the experiment, proposed gaze tracking algorithm in this paper solve the constraints that form of a display, to calculate effectively gaze direction of person in the long distance using single camera, demonstrate in experiments by distance.