• Journal of the Optical Society of Korea
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• v.15 no.2
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• pp.152-154
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• 2011

We propose a novel method which detects convex and concave corners using radial projection. The sum of two neighbors' differences at the local maxima or minima of the radial projection is compared with the angle threshold for detecting corners. In addition, the use of oriented bounding box trees and partial circles makes it possible to detect the corners of complex shapes. The experimental results show that the proposed method can separately detect the convex and concave corners, and that this method is scale invariant.

• Proceedings of the KSMRM Conference
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• 2003.10a
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• pp.18-18
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• 2003

목적： MRI 시스템에서 얻어지는 Data는 TR(Repetition Time)과 TE(Echo Time)에 따라서 신호 대잡음비(SNR), 조직들간의 대조도(Contrast), Artifact 및 촬영시간이 결정된다. 이 연구에서는 TR/TE를 줄이는 기법을 이용한 Radial Imaging 영상기법을 제시하고자 한다. 대상 및 방법： 일반적인 Radial Imaging 기법에 HASTE 기법과 Non-uniform sampling 기법의 특징을 이용하여 구현하였으며, TR/TE를 줄일 수 있었으며 얻어진 K-space Data는 가변주파수 역 Fourier Transform을 이용하여 Projection Data를 재구성한 후 Back Projection 기법을 이용하여 최종 영상을 재구성한다.

• Bulletin of the Korean Space Science Society
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• 2011.04a
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• pp.28.3-28.3
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• 2011

Halo coronal mass ejections (HCMEs) are mainly responsible for the most severe geomagnetic storms. To minimize the projection effect of the HCMEs observed by coronagraphs, several cone models have been suggested. These models allow us to determine the geometrical and kinematic parameters of HCMEs : radial speed, source location, angular width, and the angle between the central axis of the cone and the plane of the sky. In this study, we compare these parameters form two representative cone models (the ice-cream cone model and the asymmetric cone model) using well-observed HCMEs from 2001 to 2002. And we obtain the root mean square error (rms error) between observed projection speeds and calculated projection speeds for both cone models. It is found that the average rms speed error (89 km/s) of the asymmetric cone model is a little smaller than that (107 km/s) of the ice-cream cone models, implying that the radial speeds from both models are reasonably estimated. We also find that the radial speeds obtained from two models are similar to each other with the correlation coefficient of about 0.8.

• Journal of the Korean Institute of Intelligent Systems
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• v.13 no.5
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• pp.606-613
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• 2003

As a technical method for controlling chaotic dynamics, this paper presents a predictive control for chaotic systems based on radial basis function networks(RBFNs). To control the chaotic systems, we employ an on-line identification unit and a nonlinear feedback controller, where the RBFN identifier is based on a suitable NARMA real-time modeling method and the controller is predictive control scheme. In our design method, the identifier and controller are most conveniently implemented using a gradient-descent procedure that represents a generalization of the least mean square(LMS) algorithm. Also, we introduce a projection matrix to determine the control input, which decreases the control performance function very rapidly. And the effectiveness and feasibility of the proposed control method is demonstrated with application to the continuous-time and discrete-time chaotic nonlinear system.

• Journal of Convergence for Information Technology
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• v.11 no.10
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• pp.20-26
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• 2021

In this paper, we studied the rotation angle estimation methods required for image alignment in an image recognition environment. In particular, a rotation angle estimation method applicable to a low specification embedded-based environment was proposed and compared with the existing method using complex moment. The proposed method estimates the rotation angle through similarity mathcing of the 1D projection profile along the radial axis after converting an image into polar coordinates. In addition, it is also possible to select a method of using vector sum of the projection profile, which more simplifies the calculation. Through experiments conducted on binary pattern images and gray-scale images, it was shown that the estimation error of the proposed method is not significantly different from that of complex moment-based method and requires less computation and system resources. For future expansion, a study on how to match the rotation center in gray-scale images will be needed.

• Korean Journal of Digital Imaging in Medicine
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• v.3 no.1
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• pp.52-58
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• 1997

Before entering 21st Century, modern medical science is requiring more precise display which is highly estimated in diagnostic value as radial science technology is achieving sharp development. And it is also trying to contribute to improve national health and to offer better service by reducing radial exposure. General projection and Fluoroscopy which are most difficult to be displayed in digital tend to change their way ; from analog to digital with development of Electronic Engineering and Computer Technology, Introducing to CR system in 1994, SMC have displayed General projection and Fluoroscopy 100% in digital using CR system. This study searched differences between repeat rate, repeat type in the exam using Film/Screen and those in the exam using CR system. According to the analysis of repeat types and repeat rate of Film which was reused by using CR system in general projection room and Fluoroscopy room of SMC, we found that total 192,813 films were used and 2,097 films, 1.09% of total were reused. However, actual repeat covers 0.76% to 1,461 sheets with the exception of 636sheets. As above, display process using CR system is 0.76% much lower than general repeat rate 2$\sim$4% of Film/Screen exam. Besides decreased under/over exposure, it is appeared that position failure rate in repeat rate 0.76% covers relatively high 31%. Noticing that repeat caused unskilled devices handing was found many times, sufficient understanding seems to be required to reduce repeat.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.3 s.168
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• pp.107-114
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• 2005

A new approach which combines implicit surface scheme and point projection method is presented in order to fill the arbitrarily shaped holes in the polygon model. In the method a trimmed surface which has an outer boundary curve is generated by using the implicit surface scheme and normal projection of point onto the base surface. The base surface is constructed by creating smooth implicit surface from the incomplete polygon model through which the surface should pass. In this paper an implicit surface is defined by a radial basis function, a continuous scalar-valued function over the domain $R^3$. The base surface is the set of all points at which this scalar function takes on the value zero and is created by placing zero-valued constraints at the vertices of the polygon model. In order to show the validity of the present study, various hole fillings are carried out for the complex polygon model of arbitrary topology.

• Proceedings of the KSMRM Conference
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• 2003.10a
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• pp.19-19
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• 2003

목적： MRI 시스템에서 얻어지는 기초 Data는 K-space 즉 촬영대상의 Fourier Transform 된 Data 이다. 이 K-space Data는 영상 촬영 기법에 따라 다른 형식으로 얻어지게 되는데, 이 연구에서는 Radial Imaging에서 Repetition Time 과 Echo Time을 줄이기 위해 구현된 영상기법을 이용하여 얻어진 Data를 이용하여 영상을 재구성하는 방법을 제시하고자 한다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.6
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• pp.2760-2766
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• 2013

Introduction : The projection method to check existence and nonexistence of radius groove penetration of screw after distal radius fracture operation clinical using the T-type plate and the radiation of radial groove tangential is to propose a new test. Material and Methods : On the tangential projection view of radius groove, elevation angle of distal radius is 2.5, 5, 7.5, 10 degree. and forearm and radiation detector of angle is 60, 70, 80, degree each changed. that analyzed check existence and nonexistence of radius groove penetration of screw. Results : For the image of Radial groove tangential. the case of not radius groove penetration of screw(63.95%, n=55), medial penetration of radius groove(10.47%, n=9) or lateral penetration of radius groove(25.58%, n=22) was analysis. The radius groove penetrating of screw length was a range of 0.43 ~ 2.72mm, the average was 1.06mm. the check existence and nonexistence of radius groove penetration of medial or lateral was analysis that it accurate for the image of Radial groove tangential. the radiography of radial groove is well described elevation angle of distal radius 2.5 to 7.5 degree(90% over), forearm and radiation detector of angle 70degree(80%over) Conclusion : It is elevation angle of distal radius is 5degree, forearm and radiation detector of angle 70degree recommended.

• IEIE Transactions on Smart Processing and Computing
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• v.2 no.4
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• pp.203-207
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• 2013

The appropriate handling of motion artifacts is essential for clinical diagnosis in magnetic resonance imaging (MRI). In many cases, motion is an inherent part of MR images because it is difficult to control during MR imaging. As the motion in the human body occur in a deformable manner, they are difficult to deal with. This paper proposes a novel detection method for periodically moving regions to produce MR images with less motion artifacts. When the data is acquired by the radial trajectory, the proposed method can extract the deformable region easily using the difference in the modulated sinograms, which have different periodic phase terms. The simulation results applied to the various cases confirmed the good performance of the proposed method.