• Journal of Computational Design and Engineering
• /
• 제3권1호
• /
• pp.14-23
• /
• 2016

The problem of fitting B-spline curves to planar point clouds is studied in this paper. A novel method is proposed to deal with the most challenging case where multiple intersecting curves or curves with self-intersection are necessary for shape representation. A method based on Delauney Triangulation of data points is developed to identify connected components which is also capable of removing outliers. A skeleton representation is utilized to represent the topological structure which is further used to create a weighted graph for deciding the merging of curve segments. Different to existing approaches which utilize local shape information near intersections, our method considers shape characteristics of curve segments in a larger scope and is thus capable of giving more satisfactory results. By fitting each group of data points with a B-spline curve, we solve the problems of curve structure reconstruction from point clouds, as well as the vectorization of simple line drawing images by drawing lines reconstruction.

• 한국CDE학회논문집
• /
• 제21권3호
• /
• pp.234-241
• /
• 2016

Conventional bent plate used in mandibular reconstruction surgery needs safety verification since its mechanical properties are changed due to the plastic deformation during the bending process. In this study we investigate stability of the plastically deformed plate and the plate with the same shape without plastic deformation through the finite element analysis(FEA). First we simulate the process of plate bending to fit the defect in patient. Then, the other plate is modelled to represent a customized plate with the same shape of the plastically deformed one, but without any residual stresses from plastic deformation. After binding these plates to the mandible, we conduct the masticatory simulation. Finally, we compare the resulting Von Mises stress of the customized plate and of the bent plate. The bent plate shows much higher stress than the customized one due to the residual stresses form the bending process. The study shows that plastic deformation in the plate may decrease the safety of the reconstruction surgery.

• International Journal of Control, Automation, and Systems
• /
• 제3권2호
• /
• pp.211-216
• /
• 2005

In electrical impedance tomography (EIT), various image reconstruction algorithms have been used in order to compute the internal resistivity distribution of the unknown object with its electric potential data at the boundary. Mathematically, the EIT image reconstruction algorithm is a nonlinear ill-posed inverse problem. This paper presents a simulated annealing technique as a statistical reconstruction algorithm for the solution of the static EIT inverse problem. Computer simulations with 32 channels synthetic data show that the spatial resolution of reconstructed images by the proposed scheme is improved as compared to that of the mNR algorithm at the expense of increased computational burden.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2004년도 ICCAS
• /
• pp.159-164
• /
• 2004

In electrical impedance tomography (EIT), various image reconstruction algorithms have been used in order to compute the internal resistivity distribution of the unknown object with its electric potential data at the boundary. Mathematically the EIT image reconstruction algorithm is a nonlinear ill-posed inverse problem. This paper presents a simultaneous perturbation method as an image reconstruction algorithm for the solution of the static EIT inverse problem. Computer simulations with the 32 channels synthetic data show that the spatial resolution of reconstructed images by the proposed scheme is improved as compared to that of the mNR algorithm at the expense of increased computational burden.

• 대한전기학회논문지:시스템및제어부문D
• /
• 제50권2호
• /
• pp.59-64
• /
• 2001

In this paper, we propose an alternate method for determining the uniqueness of the reconstruction of a complex sequence from its phase. Uniqueness constraints could be derived in terms of the zeros of a complex polynomial defined by the DFT of the sequence. However, rooting of complex polynomials of high order is a very difficult problem. Instead of finding zeros of a complex polynomial, the proposed uniqueness criteria show that non-singularity of a matrix can guarantee the uniqueness of the reconstruction of a complex sequence from its phase-only data. It has clear advantage over the rooting method in numerical stability and computational time.

• 대한전기학회논문지:시스템및제어부문D
• /
• 제52권2호
• /
• pp.120-127
• /
• 2003

In electrical impedance tomography(EIT), various image reconstruction algorithms have been used in order to compute the internal resistivity distribution of the unknown object with its electric potential data at the boundary. Mathematically the EIT image reconstruction algorithm is a nonlinear ill-posed inverse problem. This paper presents a simulated annealing technique as a statistical reconstruction algorithm for the solution of the static EIT inverse problem. Computer simulations with the 32 channels synthetic data show that the spatial resolution of reconstructed images by the proposed scheme is improved as compared to that of the mNR algorithm or genetic algorithm at the expense of increased computational burden.

• International Journal of Advanced Culture Technology
• /
• 제10권4호
• /
• pp.175-180
• /
• 2022

To develop computational thinking skills, university students are learning how to solve problems with algorithms, program commands and grammar, and program writing. Because non-computer majors have difficulty with computer programming-related content, they need a learning method to acquire coding knowledge from the process of understanding, interpreting, changing, and improving source codes by themselves. This study explored clone coding, refactoring coding, and coding methods using reconstruction tools, which are practical and effective learning methods for improving coding skills for students who are accustomed to coding. A coding learning process with the code reconstruction principle was designed to help non-computer majors use it to understand coding technology and develop their problem-solving ability and applied the coding technology learning method used in programmer education.

• Journal of information and communication convergence engineering
• /
• 제14권1호
• /
• pp.51-56
• /
• 2016

In this paper, we present a three-dimensional (3-D) automatic target recognition system based on optical integral imaging reconstruction. In integral imaging, elemental images of the reference and target 3-D objects are obtained through a lenslet array or a camera array. Then, reconstructed 3-D images at various reconstruction depths can be optically generated on the output plane by back-projecting these elemental images onto a display panel. 3-D automatic target recognition can be implemented using computational integral imaging reconstruction and digital nonlinear correlation filters. However, these methods require non-trivial computation time for reconstruction and recognition. Instead, we implement 3-D automatic target recognition using optical cross-correlation between the reconstructed 3-D reference and target images at the same reconstruction depth. Our method depends on an all-optical structure to realize a real-time 3-D automatic target recognition system. In addition, we use a nonlinear correlation filter to improve recognition performance. To prove our proposed method, we carry out the optical experiments and report recognition results.

• 공학논문집
• /
• 제2권1호
• /
• pp.49-56
• /
• 1997

Emission computed tomography에 있어서 Bayesian방법에 근거한 통계학적 영상 재구성법이 수년간에 걸쳐 중요한 관심사로 대두되어 왔다. 이는 Bayesian 접근 방법을 사용할 경우 영상 재구성 알고리즘에 재구성하고자 하는 영상에 대한 사전정보를 포함시킬 수 있기 때문이었다. 이러한 방법은 경우에 따라 향상된 성능을 보이고 있으나, 막대한 계산시간으로 인해 실제 임상에 적용되기가 매우 어려운 상황이다. 한편, filtered backprojection(FBP)은 알고리즘 자체가 간단하고 계산시간도 매우 단축되므로 대부분의 임상에 널리 적용되고 있다. 본 연구에서는 Bayesian 영상 재구성에서 매우 유용하게 사용되는 spline 모델을 FBP의 고주파 감쇠를 위한 정칙자로 사용함으로써 FBP 영상 재구성에 Bayesian 방법과 유사한 효과를 얻을 수 있음을 보인다.

• 한국전산유체공학회지
• /
• 제12권1호
• /
• pp.1-8
• /
• 2007

A code is developed using the hybrid Cartesian/immersed boundary method and it is applied to simulate flows around a three-dimensional deforming body. A new criterion is suggested to distribute the immersed boundary nodes based on edges crossing a body boundary. Velocities are reconstructed at the immersed boundary nodes using the interpolation along a local normal line to the boundary. Reconstruction of the pressure at the immersed boundary node is avoided using the hybrid staggered/non-staggered grid method. The developed code is validated through comparisons with other experimental and numerical results for the velocity profiles around a circular cylinder under the forced in-line oscillation and the pressure coefficient distribution on a sphere. The code is applied to simulate the flow fields around a plate whose tail is periodically flapping under a translation. The effects of the velocity and acceleration due to the deformation on the periodic shedding of pairs of tip vortices are investigated.