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SLA를 이용한 신속시작작업을 위한 지지대 자동생성 시스템의 개발
허정훈,이건우,Hur, Junghoon,Lee, Kunwoo 대한기계학회 1996 大韓機械學會論文集A Vol.20 No.10
stereolithography is a process used to rapidly produce polymer components directly from a computer representation of the part. There are several considerations to be made for the efficient use of the process. Especially, the necessity of support structures, which prevent the part from warping, sagging, or parachuting and toppling as the elevator moves up and down in the resin, is one concern. After solidification, the support structures must by removed in the end. Bacause this post-treatment process is often performed manually, the more the support structures, the more it increases the finishing operations. Especially for a complicated part, the removal operations may be difficult, take so much time, and even reduce the accuracy of the product. Thus it is important to efficiently generate the efficient support structure for each part geometry. This paper proposes a procedure to automatically generate the supprot structures focused on accuracy, efficiency, convenience, and generation speed.
Initial closed curve for active contour model on mesh
JuSung Lee(이주성),JeongHun Lim(임정훈),Kunwoo Lee(이건우) (사)한국CDE학회 2015 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2015 No.동계
The accurate margin line extraction is a crucial process in computer-aided orthodontics. Margin line is boundary line of treatment region. Though curvature field is traditionally used for detect feature line, different shapes and scanning noises make hard to detect margin line automatically. Thus current dental CAD systems mostly require the user interactive definition of points by the user. So, we also use interactive defined starting points by the user. In medical image processing, active contour model is used to extract feature line. However it doesn’t work when initial curve is improper. To solve this problem, this paper proposes a novel closed curve initialization algorithm that makes initial curve on mesh by using starting points. Some experiments show our initialization method is robust and fast.
인솔 설계 변수에 따른 발목 과-회내 환자의 보행 시 좌우 방향 무릎 관절 하중의 변화
이상준(SangJun Lee),백승엽(Seung-Yeob Baek),손진규(JinKyou Son),김동욱(Dongwook Kim),이건우(Kunwoo Lee) (사)한국CDE학회 2012 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2012 No.2
The over-pronation of the knee joint causes the mechanical overloading transferred to proximal areas (i.e. ankles, knees, or hips) over time. Thus, the over-pronation is recognized as a contributory factor in a wide variety of musculo-skeletal pathologies in lower extremities. Commonly, over-pronated ankles are treated using specially designed insoles that support medial heels and correct the posture of lower limbs. However, the biomechanical effects of the insoles are not yet fully understood, so there still are controversies whether such insoles really have clinical significance. In this study, in order to verify the effects of insoles and determine the best shape of the insoles, we examined how the medio-lateral knee joint reaction force changes due to insole conditions. As shape parameters of insoles, the medio-lateral heel post angle and the arch support height were chosen. We then collected marker trajectories and ground reaction forces and moments of one male subject with overpronation walking with different insole conditions. The OpenSim software was employed for the simulation of each trial. Finally, the medio-lateral knee joint reaction force curves of each trial were plotted, and the efficacy of each insole condition was evaluated by comparing their peak values. As a result, it is revealed that the medial heel post, which drastically reduced the peak medio-lateral knee joint reaction force, has significant effects on the gait of the over-pronated patients. However, in case that the arch support is combined together, the positive effect of the medial heel post may rather decrease.
인솔 설계 변수에 따른 발목 과-회내 환자의 보행 시 좌우 방향 무릎관절 하중의 변화
이상준(SangJun Lee),백승엽(Seung-Yeob Baek),손진규(JinKyou Son),김동욱(Dongwook Kim),이건우(Kunwoo Lee) (사)한국CDE학회 2012 한국CDE학회 논문집 Vol.17 No.3
The ankle over-pronation causes the mechanical overloading transferred to proximal areas (i.e. knees or hips) over time. Thus, the over-pronation is recognized as a contributory factor in a wide variety of musculo-skeletal pathologies in lower extremities. Commonly, over-pronated ankles are treated using specially designed insoles that support medial heels and correct the posture of lower limbs. However, the biomechanical effects of the insoles are not yet fully understood, so there still are controversies whether such insoles really have clinical significance. In this study, in order to verify the effects of insoles and determine the best shape of the insoles, we examined how the medio-lateral knee joint reaction force changes due to insole conditions through a case study about a subject. As a result, it is revealed that the medial heel post, which drastically reduced the peak medio-lateral knee joint reaction force, has significant effects on the gait of the over-pronated patients. However, in case that the arch support is combined together, the positive effect of the medial heel post may rather decrease.
컴퓨터를 이용한 의료 진단용 3 차원 척추 제네릭 모델
이주성(Jusung Lee),백승엽(Seung-Yeob Baek),이건우(Kunwoo Lee) (사)한국CDE학회 2010 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2010 No.1
CT 나 MRI 와 같은 기존 3 차원 의료 영상 획득방법은 많은 비용과 시간이 소모된다는 단점을 가지고 있다. 또한 CT 영상은 다른 방법들에 비하여 방사선 피폭량이 상대적으로 많으므로, 이로인한 부작용 또한 문제점으로 지적될 수 있다. 이러한 기존방법들의 단점을 개선하기 위하여 최근 ART(Algebraic Reconstruction Technique)와 같이 몇 장의 X-ray 영상 만으로 환자의 3 차원 영상을 획득할 수 있는 기술들이 개발된 바 있다. 이러한 기술들은 하나의 제네릭 모델을 X-ray 영상에 맞게 적절히 변형시킴으로써 구현될 수 있는데, 제네릭 모델의 초기 형상에 따라 계산 속도나 결과물의 형상 등이 달라질 수 있다. 이러한 사실에 착안하여 우리는 통계적 자료를 근거로 3 차원 척추(C1) 제네릭 모델을 생성하고, 이를 여러 환자 각각에 특화된 모델(patient-taylored model)로 변형시키는 방법을 제안한다. 우리는 이 논문을 통해 CT 촬영으로 얻은 여러 개의 3 차원 척추 모델 데이터들의 메쉬 토폴로지를 일치시키고, 이를 기반으로 통계 데이터베이스를 구축하는 방법에 대해 논의한다. 나아가 이러한 통계 데이터베이스에 대한 수학적인 분석을 통하여 척추 형상 분포의 경향성을 찾아내고, 이를 종합하여 손쉽게 환자에게 특화된 제네릭 모델을 생성하는 방법에 대해서도 논의할 것이다. 이러한 방법으로 환자에게 특화되어 생성된 제네릭 모델을 이용하게 되면 X-ray 영상으로부터 3 차원 모델을 생성함에 있어서 그 처리 속도 뿐만아니라 정확도 또한 증대시킬 수 있다. 또한 이러한 방법론은 본 논문에서 주로 초점을 맞추고 있는 C1(Atlas) 뿐 아니라 다른 부위의 뼈 형상들에 대해서도 동일하게 적용할 수 있기 때문에, 앞으로 의료 영상 분야에서 다양한 응용이 가능하리라 기대된다.