• Korean Journal of Applied Biomechanics
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• v.16 no.1
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• pp.81-88
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• 2006

Present study is to know the relation with throwing speed according to the uniform torque by the shoulder joint, over 20 persons of professional baseball, and were measured the uniform torque by the shoulder joint accordance with throwing speed between (A-low speed) and (B-high speed) of each group. In the present study, three components were measured, and analyzed with having an approximated output value appearing by changing angular velocity, and in $30^{\circ}/sec$, the maximum strength of muscles was measured, and in$210^{\circ}/sec$, the points of endurance strength of muscles were measured and analyzed, and the following result could be obtained. 1. In muscles strength (peak torque)of inner rotation, and outer rotation for respect to each speed of shoulder joint, though there did not appear outstanding difference between A group and B group in the $30^{\circ}/sec$, it showed that group B has priority in a little. Also in outer rotation by shoulder joint, though there appeared the same difference between A group and B group, B group is tended to be prior to A group in a little. 2 In the view of muscles strength (peak torque)of inner rotation, and outer rotation for respect to each speed of shoulder joint, though there did not appear outstanding difference between A group and B group in the $30^{\circ}/sec$, it showed that group B has priority in a little. Also in outer rotation by shoulder joint, though there appeared the same difference between A group and B group, B group is tended to be prior to A group in a little. 3. In the view of muscles strength(peak torque)of inner rotation, and outer rotation for respect to each speed of shoulder joint, though there did not appear outstanding difference between A group and B group in the $30^{\circ}/sec$, it showed that B group has priority in a little. Also in outer rotation by shoulder joint, though there appeared the same difference between A group and B group, B group is tended to be prior to A group in a little. 4. In the view of peak torque for respect to the weight accordance with each velocity of shoulder joint, there did not appear outstanding difference between A group and B group. In outer rotation by the shoulder joint, there was not appeared clear difference between A group and B group. 5. In the concern of the peak torque for respect to the weight accordance with each velocity of shoulder joint, there did not appear outstanding difference between A group and B group in $30^{\circ}/sec$. In outer rotation by the shoulder joint, there was not appeared clear difference between A group and B group. 6. In the concern of the peak torque for respect to the weight accordance with each velocity of shoulder joint, there did not appear outstanding difference between A group and B group in $210^{\circ}/sec$. In outer rotation by the shoulder joint, there was not appeared clear difference between A group and B group. As conclusion, there did not appear a correlation of uniform torque by shoulder joint versus the speed throwing by a pitcher of professional base ball.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.4
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• pp.532-539
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• 2007

The 7075-T651 Al alloy was welded by friction stir welding. Microstructure, macro behaviors and fracture type in the nugget, thermo-mechanically affected zone(TMAZ) and heat affected zone(HAZ) of the welded part were compared to base metal. The microsturctures of nugget zone were compared with tool rotation speeds and various tool transition speed. When the rotation speeds were decreased and transition speeds were increased, the hardness of nugget zone were decreased. Also, the optimal microstructure was observed at the low rotation speed of 800rpm and the high transition speed of 124mm/min. The transgranular dimple and quasi-cleavage at fractured part of nugget zone were investigated.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.5
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• pp.1-6
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• 2016

Image rotation is one of main pre-processing step in image processing or image pattern recognition. It is implemented with rotation matrix multiplication. However it requires lots of floating point arithmetic operations and trigonometric function calculations, so it takes long execution time. We propose a new high speed image rotation algorithm without two major time-consuming operations. It use just 2 shear translation operations, so it is very fast. In addition, we apply a parallel computing technique with CUDA. CUDA is a massively parallel computing architecture using prevailed GPU recently. As GPU is a dedicated graphic processor, it is exellent for parallel processing of pixels. We compare the proposed algorithm with the conventional rotation one with various size images. Experimental results show that the proposed algorithm is superior to the conventional rotation ones.

• Korean Journal of Applied Biomechanics
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• v.16 no.1
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• pp.55-63
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• 2006

The purpose of this study is to prove the kinematical characteristics of Deff motion, the high bar performance, in terms of flying phases so that we can provide basic sources for improving gymnastic performance. To do this, we selected and analyzed the performance of two athletes who did Deff motion in the high bar competition of male artistic gymnastic in the 22nd Universiade 2003 Daegu. We drew the conclusions from the kinematical factors that were came out through analyzing three-dimensional cinematography of the athletes' movements, by using a high speed video camera. To make a successful performance, a performer releases the bar at a height of a high bar vertically and at a height of 82cm horizontally, and the flying performance should be made without moving forward, as maintaining the proper balance, in order to rise over 118cm high during the flying phase. When the performer is releasing the bar, an increase of the vertical speed in the center of the body and extension of a knee joint and a hip joint contribute to increasing a flying height. And when the moving body is twisted, leaning to left side is caused by the winding movement of a knee joint, which causes an unstable bar grasp. To grasp the bar stably, just before releasing the performer should gain propulsive force from twisting rotation through increasing the speed of shoulder rotation. And before the peak point, the performer should make sure of a body rotation distance over $164^{\circ}$ so that he or she can do an aerial rotary performance smoothly. When grasping the high bar, the center of the body should be above the bar and the angle of shoulder rotation should be maintained close to $540^{\circ}$ simultaneously. he high point performance(S1) has more speed on an ascending phase and less speed on a descending phase than the low point performance (S2). At the peak point, both the rotation angle of the body and that of the shoulder in high point performance are big as well. In conclusion, it is shown that a performer can make a jump toward the high bar easily with the body straight because the performer can hold the upper part of the body erect early in a descending phase.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.27 no.2
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• pp.37-43
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• 2004

High speed machining is a machining process which cuts materials with the fast movement and rotation of a spindle in a machine tool. It reduces machining time because of the high feed and the high speed of a spindle. In addition it gets rid of post processes for high precision machining. When the high speed machining is applied to especially hardened steel, operators should select the proper parameters of machining. This can produce machining surfaces which is qualified with good surface roughness. This paper presents a method for selecting machining parameters to minimize surface roughness with high speed machining in cutting the hardened steels. Experimental data for surface roughness are collected in a machining shop based on the cutting feed and the spindle rotation. The data fits in hi-cubic polynomial surface of mathematical form. From the model this research minimize the surface roughness to find the optimal values of the feed and the spindle speed. This paper presents a program which automatically generates optimal solutions from the raw data of experiments.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.1
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• pp.51-57
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• 1998

In order to minimize vibration problems of rotating machinery rotors have been assembled through balancing machines. Since perfect balancing is impossible, residual unbalances cause serious vibration while the rotor is in high speed region. To minimize unbalance effects of magnetic bearing systems (AMB) during rotation on-line balancing methodology was studied. Unbalances were considered as disturbances of the system. The disturbance observer was used to estimate unbalance force from measurable state and input variables. Balancing inputs computed according to LQR and outputs of the observer were applied to eliminate unbalances during high speed rotation of the AMB. the effectiveness of the on-line balancing was verified through numerical simulations.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10a
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• pp.6-11
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• 1988

Alight-weight robot arm carrying a payload is modelled as a cantilever beam with a tip mass subjected to a high speed rotation. Equations of Motion, for modal control, are represented as discrete state variable form. Digital optimal control law with observer is developed to suppress the arm vibration and control the position of the joint angle. The effects of the number of controlled modes, weighting factors of the performance index, reference rotation time, and sampling time on the control performance are analyzed by computer simulation and experiments.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1583-1593
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• 2011

As we see the continuation of the increase in the speed of the High Speed railroad worldwide, there is a concern for a possible problem in the connecting transition zone in the railway infrastructure. Honam High Speed railroad's transition zone in the hub for the rotation structures and other supporting structures such as approach slab, sub slab, approach block, etc. Due to its increase in speed of the design speed, and its important role on the driving stability and credibility of the bearing ground performance, we must seek and fine a prevention plan for a cause of differential settlement, as well as the cause of the derailment. In this dissertation, domestic, as well as international design manuals and the applicability of the control standards are studied. Also through the study target, Honam High Speed railroad zone 4-1, we evaluated the connecting componant of the Yeon-Jeong bridge through the eigenvalue and weight transfer of the train when operated at 300km/h, 350km/h, 400km/h, 450km/h, and were able to achieve detailed assessment by checking track behaviors, looking at various components such as the rotation acceleration according to the inversion of the distance length, displace length, displacement and stress distribution. Through these studied, possibility of operating at 400km/h was evaluated based on the condition of the current design basis.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.328-330
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• 1994

The Ultrasonic motor(USM) has many good characteristics such as high torque at low speed range, large holding torque based upon frictional force, high speed response, flexible free ferns, compactness in size, low magnetic noise and silentness in motion. Because of having low speed rotation, USM is good as an actuator of a small size direct drive (DD) manipulator. The acturators for the DD manipulators must have good controllability on the speed and torque from zero to maximum value continuously. New method was developed for speed and torque control by the phase difference control of the two-phase driving signals of the motor. Then rule adjustable compliant and dumped motion was realized on the output shaft of the motor by PD control of the output shaft angle.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.5
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• pp.402-410
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• 2004

To obtain a good tracking performance in an optical disk drive servo system, it is essential to attenuate periodic disturbances caused by eccentric rotation of the disk. As an effective control scheme for enhancing disturbance attenuation performance, disturbance observers (DOBs) have been successfully applied to the track-following servo system of optical disk drives. In disk drive systems, the improvement of data transfer rate has been achieved mainly by the increase of disk rotational speed, which leads to the increase of the disturbance frequency. Conventional DOBs are no longer effective in disk drive systems with a high-speed rotation mechanism because the performance of conventional DOBs is severely degraded as the disk rotational frequency increases. This paper proposes a new DOB structure for effective rejection of the disturbance in optical disk drives with a very high rotation speed. Asymptotic disturbance rejection is achieved by adopting a band-pass filter in the DOB structure, which is tuned based on the information on the disturbance frequency. In addition, performance sensitivity of the proposed DOB to changes in disk rotational frequency is analyzed. The effectiveness of the proposed DOB is verified through simulations and experiments using a DVD-ROM drive.