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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.
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.
이주성(Jusung Lee),백승엽(Seung-Yeob Baek),이건우(Kunwoo Lee) (사)한국CDE학회 2011 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2011 No.1
Medical image acquisition techniques such as CT and MRI have disadvantages in that the numerous time and efforts are needed. Furthermore, a great amount of radiation exposure is an inherent proberty of the CT imaging technique, a number of side-effects are expected from such method. To improve such conventional methods, a number of novel methods that can obtain 3D medical images from a few X-ray images, such as algebraic reconstruction technique (ART), have been developed. Such methods deform a generic model of the internal body part and fit them into the X-ray images to obtain the 3D model; the initial shape, therefore, affects the entire fitting process in a great deal. From this fact, we propose a novel method that can generate a 3D vertebraic generic model based on the statistical database of CT scans in this study. Moreover, we also discuss a method to generate patient-tailored generic model using the facts obtained from the statistical analysis. To do so, the mesh topologies of CTscanned 3D vertebra models are modified to be identical to each other, and the database is constructed based on them. Furthermore, from the results of a statistical analysis on the database, the tendency of shape distribution is characterized, and the modeling parameters are extracted. By using these modeling parameters for generating the patient-tailored generic model, the computational speed and accuracy of ART can greatly be improved. Furthermore, although this study only includes an application to the C1 (Atlas) vertebra, the entire framework of our method can be applied to other body parts generally. Therefore, it is expected that the proposed method can benefit the various medical imaging applications.
이주성(Jusung Lee),백승엽(Seung-Yeob Baek),이건우(Kunwoo Lee) (사)한국CDE학회 2010 한국CDE학회 논문집 Vol.15 No.4
Medical image acquisition techniques such as CT and MRI have disadvantages in that the numerous time and efforts are needed. Furthermore, a great amount of radiation exposure is an inherent proberty of the CT imaging technique, a number of side-effects are expected from such method. To improve such conventional methods, a number of novel methods that can obtain 3D medical images from a few X-ray images, such as algebraic reconstruction technique (ART), have been developed. Such methods deform a generic model of the internal body part and fit them into the X-ray images to obtain the 3D model; the initial shape, therefore, affects the entire fitting process in a great deal. From this fact, we propose a novel method that can generate a 3D vertebraic generic model based on the statistical database of CT scans in this study. Moreover, we also discuss a method to generate patient-tailored generic model using the facts obtained from the statistical analysis. To do so, the mesh topologies of CTscanned 3D vertebra models are modified to be identical to each other, and the database is constructed based on them. Furthermore, from the results of a statistical analysis on the database, the tendency of shape distribution is characterized, and the modeling parameters are extracted. By using these modeling parameters for generating the patient-tailored generic model, the computational speed and accuracy of ART can greatly be improved. Furthermore, although this study only includes an application to the C1 (Atlas) vertebra, the entire framework of our method can be applied to other body parts generally. Therefore, it is expected that the proposed method can benefit the various medical imaging applications.
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.