• The Journal of the Korea institute of electronic communication sciences
• /
• v.14 no.2
• /
• pp.411-416
• /
• 2019

In this paper, we describe a measurement system based on vision for detecting the rotation axis of dimpled golf ball. Some golf balls have wrong rotation axis owing to bad production and scratch. A flying golf ball makes sliced or curved motion mainly to owing the wrong rotation axis of golf ball. Dimples of golf ball make a golf ball higher and more straight flying. When we hit a golf ball by driver or iron club, the dimpled ball flies straight and rotates as well. While the ball flying, the rotating axis of the ball convergence. And this makes the ball motion curved. If we hit a golf ball in direction of the rotation axis, the flying ball makes straight motion. In this paper, we develop a control system to detect convergence axis and time of flying golf ball based on vision system. To show validity of the developed system, We experimented several case for dimpled golf balls.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.05a
• /
• pp.190-190
• /
• 2004

목표물이 시선의 중심에서 벗어났을 때 모터를 구동시켜 목표물을 시선의 중심에 고정시킴과 동시에 외란으로 인한 카메라의 시선이 흔들리는 것을 막아주는 것을 시선 안정화 시스템이라 한다. 이러한 시스템은 능동 서스펜션 역할출 하는 서보제어기 설계기술이 요구된다. 이론 위하여 본 연구에서는 3축의 회전운동이 가능하고 회전운동에 따른 카메라의 시선의 회전축이 일체화가 되도록 하는 짐벌(gimbals) 구조를 설계한다.(중략)

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 1990.06a
• /
• pp.45-52
• /
• 1990

고도의 신뢰도를 요구하는 정밀기계의 보편화는 트라이볼로지 요소중에서 밀봉기능에 관련된 시일의 해석 및 설계가 커다란 관심사로 부각되었다. 특히 고속회전을 요하는 경우에 대한 회전 시스템의 동적 안정성은 대단히 중요하다. 미끄럼 접촉운동을 하고 있는 기계평면시일의 시일링 간극은 대단히 작기 때문에 시일의 접촉면에서 형상이 변화하게 되면 시일 성능은 커다란 영향을 받게 된다. 시일의 접촉표면 가공시 발생되는 평면도(flatness), 조립시의 회전축과 시일축 사이의 중심 맞추기의 어려움, 회전축의 자중량 등 때문에 발생되는 회전링 사이의 상대적인 경사도(misalignment)는 시일의 동적 불안정성에 영향을 준다. 또한 상대 접촉 운동면에서 경계 또는 고체 마찰에 의한 마멸의 진행은 시일의 코닝(coning) 현상을 일으킨다. 본 연구에서는 비압축성 유체가 온도의 영향을 받아 점도가 선형적으로 변화하는 경우에 대한 시일링 간극 내에서의 압력분포를 유한차분법을 이용하여 해석하였다. 여기서 얻어진 결과를 이용하여 시일의 축력과 모우멘트를 해석함으로써 시일의 동적 불안정성에 대하여 논하였다. 이 때 기계평면 시일의 형상은 코닝이 있고, 시일의 중심축이 경사진 경우를 고려하였다.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.14 no.9
• /
• pp.4191-4196
• /
• 2013

In this paper, structural analysis was made on two cases in order to develop free rotational method and rotational angle in LCD monitor. The configuration of LCD monitor in field was modeled by using 3-D design program CATIA V5 and structural analysis was done to the modeled LCD in order to obtain stress, strain and total deformation by using ANSYS finite element analysis program.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.43 no.7
• /
• pp.648-656
• /
• 2015

Active SAR satellite's main maneuver is roll axis maneuver to change SAR antenna direction. In addition, yaw steering is required to minimize the doppler centroid variation. Thus, it is resonable to assign the torque/momentum capacity mostly to roll axis and then yaw axis. In this case, the pitch axis shows low agility performance. However, due to orbit maintenance, large angle maneuver about pitch axis is sometimes required. In this paper, we study the pitch axis maneuver time reduction through sequential rotation about roll and yaw axis. Since these two axes have high agility performance than pitch axis, maneuver time reduction is possible when large angle rotation about pitch axis is required.

• Proceedings of the Korean Society of Radiological Science
• /
• 1996.06a
• /
• pp.18.1-18.1
• /
• 1996

• Journal of Radiation Protection and Research
• /
• v.33 no.2
• /
• pp.47-51
• /
• 2008

Objective: This study analyzed errors due to rotation or tilt of the magnetic resonance (MR) imaging indicator during image acquisition for a stereotactic radiosurgery. The error correction procedure of a commercially available stereotactic neurosurgery treatment planning program has been verified. Materials and Methods: Software virtual phantoms were built with stereotactic images generated by a commercial programming language, Interactive Data Language (version 5.5). The thickness of an image slice was 0.5 mm, pixel size was $0.5{\times}0.5mm$, field of view was 256 mm, and image resolution was $512{\times}512$. The images were generated under the DICOM 3.0 standard in order to be used with Leksell GammaPlan$^{(R)}$. For the verification of the rotation error correction function of Leksell GammaPlan$^{(R)}$, 45 measurement points were arranged in five axial planes. On each axial plane, there were nine measurement points along a square of length 100 mm. The center of the square was located on the z-axis and a measurement point was on the z-axis, too. Five axial planes were placed at z=-50.0, -30.0, 0.0, 30.0, 50.0 mm, respectively. The virtual phantom was rotated by $3^{\circ}$ around one of x, y, and z-axis. It was also rotated by $3^{\circ}$ around two axes of x, y, and z-axis, and rotated by $3^{\circ}$ along all three axes. The errors in the position of rotated measurement points were measured with Leksell GammaPlan$^{(R)}$ and the correction function was verified. Results: The image registration errors of the virtual phantom images was $0.1{\pm}0.1mm$ and it was within the requirement of stereotactic images. The maximum theoretical errors in position of measurement points were 2.6 mm for a rotation around one axis, 3.7 mm for a rotation around two axes, and 4.5 mm for a rotation around three axes. The measured errors in position was $0.1{\pm}0.1mm$ for a rotation around single axis, $0.2{\pm}0.2mm$ for double and triple axes. These small errors verified that the rotation error correction function of Leksell GammaPlan$^{(R)}$ is working fine. Conclusion: A virtual phantom was built to verify software functions of stereotactic neurosurgery treatment planning program. The error correction function of a commercial treatment planning program worked within nominal error range. The virtual phantom of this study can be applied in many other fields to verify various functions of treatment planning programs.

• Korean Journal of Applied Biomechanics
• /
• v.19 no.4
• /
• pp.779-791
• /
• 2009

The purpose of this study is to develop a program that computes the position of the instantaneous center of rotation while an object moves in a circular motion. For this study, a mathematical algorithm was developed and implemented on the experimental data. Data for pitching (40m carry) and putting (4m) strokes were obtained from a skilled female golfer. A computer program (Centering 1.0) calculated the experimental data and found the radius of the instantaneous center of rotation. When the data were taken broadly, the program produced an error distance of radius. When the data were divided gradually, the program produced a very close instantaneous center of rotation. On comparing pitching and putting strokes, putting was found to have a greater radius than pitching. The instantaneous centers of rotation of putting were not in the golfer's body rather, they were 3m away from the club head. The Centering 1.0 program can calculate the instantaneous center of rotation with at least three sets of experimental data.

• Geotechnical Engineering
• /
• v.1 no.1
• /
• pp.21-30
• /
• 1985

The reasonable static and dynamic earth pressure equations were developed by applying the Dubrova's theory and Chang's method to the following cases of wall movements; (1) Active case rotating about the top (2) Active case rotating about the bottom (3) Passive case rotating about the top (4) Passive case rotating about the bottom The equations are presented in accordance with particular wall displacements for the sand and cohesive back-fill, respectively. The results computed by the proposed equations are compared with the conventional theoretical values.

• Journal of KIISE:Software and Applications
• /
• v.31 no.4
• /
• pp.411-419
• /
• 2004

When the imaging object rotates in image plane during MRI scan, its rotation causes phase error and non-uniform sampling to MRI signal. The model of the problem including phase error non-uniform sampling of MRI signal showed that the MRI signals corrupted by rotations about an arbitrary center and the origin in image plane are different in their phases. Therefore the following methods are presented to improve the quality of the MR image which includes the artifact. The first, assuming that the angle of 2-D rotational motion is already known and the position of 2-D rotational center is unknown, an algorithm to correct the artifact which is based on the phase correction is presented. The second, in case of 2-D rotational motion with unknown rotational center and unknown rotational angle, an algorithm is presented to correct the MRI artifact. At this case, the energy of an ideal MR image is minimum outside the boundary of the imaging object to estimate unknown motion parameters and the measured energy increases when the imaging object has an rotation. By using this property, an evaluation function is defined to estimate unknown values of rotational angle at each phase encoding step. Finally, the effectiveness of this presented techniques is shown by using a phantom image with simulated motion and a real image with 2-D translational shift and rotation.