• Journal of Mechanical Science and Technology
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• v.14 no.11
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• pp.1250-1256
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• 2000

Rubbing occurs when a rotor contacts with a stator during whirling motion of the rotor. Compared to full annular rub, partial rub against a nonrotating part is more common in practice. In this study, several partial rubbing phenomena of superharmonic and subharmonic vibrations and jump phenomenon are demonstrated experimentally for the cases of light and heavy rub for a flexible rotor. The orbit patterns of forward or backward whirling are also calculated using directional spectrum analysis. The occurrence if subharmonic vibration during heavy rub is demonstrated as one impact per two rotations both experimentally and numerically.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1995.04a
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• pp.880-885
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• 1995

This paper deals with the efficient planning of robot motions in the Cartesian space while avoiding the collision with obstacles. The motion planning problem is to find a path from the specified starting robot configuration that avoids collision with a known set of stationary obstacles. A simple and efficient algorithm was developed using "Backward" approach to solve this problem. The computational result was satisfactory enough to real problems. problems.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1995.06a
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• pp.105-108
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• 1995

본 논문에서는 초기 비트율 부호화(very low bit-rate coding)를 위한 새로운 움직임 예측 부호화를 제안한다. 움직임 추정 및 움직임 보상은 영역 기반으로 행해지며, 움직임 보상 후 예측 오차는 DCT(Discrete Cosine Transform)를 통해 변환되어 부호화 된다. 제안된 내용으로는 이전 영상을 이용하여 역방향(backward) 움직임 추정 후 얻어지는 움직임 벡터를 이용하여 움직임 보상된 영상을 구성하고, 여기에 보상되지 않은 영역은 순방향(forward) 움직임 추정을 선택적으로 행함으로써 영상을 재구성한다. 제안된 알고리듬은 모의 실험 결과 양질의 화질을 얻었다.

• The Journal of Korea Robotics Society
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• v.15 no.4
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• pp.309-315
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• 2020

This study shows a control strategy that acquires both precision and manipulation sensitivity of remote center motion with manual traction for a surgical assistant robot. Remote center motion is an essential function of a laparoscopic surgical robot. The robot has to keep the position of the insertion port in a three-dimensional space, and general laparoscopic surgery needs 4-DoF (degree-of-freedom) motions such as pan, tilt, spin, and forward/backward. The proposed robot consists of a 6-axis collaborative robot and a 2-DoF end-effector. A 6-axis collaborative robot performs the cone-shaped trajectory with pan and tilt motion of an end-effector maintaining the position of remote center. An end-effector deals with the remaining 2-DoF movement. The most intuitive way a surgeon manipulates a robot is through direct teaching. Since the accuracy of maintaining the remote center position is important, direct teaching is implemented based on position control in this study. A force/torque sensor which is attached to between robot and end-effector estimates the surgeon's intention and generates the command of motion. The predefined remote center position and the pan and tilt angles generated from direct teaching are input as a command for position control. The command generation algorithm determines the direct teaching sensitivity. Required torque for direct teaching and accuracy of remote center motion are analyzed by experiments of panning and tilting motion.

• The Korean journal of sports medicine
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• v.36 no.4
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• pp.197-206
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• 2018

Purpose: This study analyzed the muscle activity changes induced by motions of reaching forward and chest expansion that were examined from the bilateral muscles with rectus abdominis, external oblique, multifidus, and longissimus thoracic using Pilates cadillac instrument. Methods: Nine young adult women, who have no musculoskeletal disorder and any of chronic diseases, were participated. Surface electromyography system was used for recording of all signals produced by muscles, and then normalized as percentage of maximum voluntary isometric contraction (%MVIC). The paired t-test and repeated measures of analysis of variance was performed. Results: Reaching-forward motion showed a higher muscle activity from non-dominant external oblique muscle than that of the chest-expansion motion. During both reaching-forward motion and chest-expansion motion, MVIC values collected from dominant side of external oblique muscle were shown a significantly lower than the values obtained from non-dominant side (p<0.05). Conversely, %MVIC values in external oblique muscle collected from dominant side showed a significantly higher than the values obtained from non-dominant side of the same oblique muscle (p<0.05). Reaching-forward motion was caused a higher %MVIC on non-dominant external oblique muscle than that of the chest-expansion motion (p<0.05). Regardless of dominant or non-dominant sides, external oblique muscle was shown the highest activation rate of all the other muscles during reaching forward action, and longissimus thoracic muscle was shown the highest activation rate of all the other muscles during chest expansion action. Conclusion: Reaching-forward motion is suitable for activating an external oblique muscle, and chest-expansion motion is an effective enough in activating of longissimus thoracic muscle.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2010.07a
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• pp.24-27
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• 2010

움직임 보상 외삽 기법은 전송중 손상된 프레임의 복원 및 프레임율 증가 뿐 아니라 분산 동영상 부호화 시스템(distributed video coding:DVC)의 부가 정보(side information) 생성에도 활용될 수 있다. 본 논문에서는 기존의 다양한 움직임 보상 외삽기법의 성능을 평가하고 정방향과 역방향 움직임 예측을 함께 이용한 효율적인 움직임 보상 외삽 기법을 제안한다. 모의 실험결과 제안하는 기법이 기존의 기법에 비해서 우수한 성능을 보임을 확인하였다.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.05a
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• pp.75-78
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• 1999

This paper is concerned with the family of parts that generally feature a central hub with radial protrusions. Typical parts that fall into this category include cross Pieces for universal joints, tube fittings, and differential gears. As opposed to conventional forward and backward extrusion, in which the material flows in a direction parallel to that of the punch or die motion, the material flows perpendicular to the punch motion in radial extrusion. In this study, the forming characteristics of radial extrusion will be considered by comparing the forces, shapes etc. The design factors during radial extrusion are investigated by the rigid-plastic FEM simulation.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.963-968
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• 2005

For worm robots applied to pipe inspection and colonoscopy, earthworm-like robots that have a locomotion pattern in backward wave or green caterpillar-like robots that have a locomotion pattern in forward wave have been studied widely. Note however that a method using a single and fixed locomotion pattern is not desirable in the sense of mobility cost, if there are various changes in pipe diameter. In this paper, locomotion patterns are considered for a semi-looper-like robot, which adopts a locomotion pattern of green caterpillars as the basic motion and sometimes can realize a locomotion pattern of looper, whose motion approximately consists of two rhythms or relatively low rhythm.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.854-857
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• 2001

At present, colonoscopy is performed by means of quite long and flexible endoscopes and controlled manually. Although the flexibility of the distal tip allows the endoscope to follow the tortuous path of the colon, the insertion of the endoscope requires the endoscopist to exert forces on and to perform rotations of the proximal end; these actions cause discomfort to the patient. Though self-propelling colonoscopic systems has been suggested to overcome these problems, it is difficult to pass through highly curved regions of the intestine. In this paper, we introduce a steering mechanism for a self-propelling coloinlscope, the smart capsule, which has three actuator units. The mechanism is designed not only to move forward and backward but also to pass through the curved regions. We derived the governing equations of this mechanism. Active movements and motion control are developed.