• Journal of Biomedical Engineering Research
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• v.31 no.2
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• pp.151-161
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• 2010

Soft Golf is a newly developed recreational sport in our research team aimed to become a safe and easy-to-learn sport for all ages. The advantage of Soft Golf stems from lighter weight of the club and much larger area of the sweet spot. The purpose of this study is to analyze ground reaction force(GRF) and joint angle during soft Golf club and regular golf club swing. The GRF of golf swing was recorded by 3-D motion analysis system and forceplate. The joint angle of golf swing was obtained from computer simulation model. The GRF and joint angle of golf swing are used to analysis of golf swing pattern. The pattern of GRF and joint angle during soft golf club swing was similar to that during regular golf club swing. This result means that soft golf club reduces the risk of injury and has an effect on similar entertainment of regular golf.

• Korean Journal of Applied Biomechanics
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• v.32 no.4
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• pp.147-152
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• 2022

Objective: The purpose of this study was to analyze the effects of club head and golf ball kinematics and body alignment according to the swing plane during golf driver swing. Method: Sixteen college golfers participated in this study. Kinematic data of the club head and golf ball were collected using golf swing analysis system (Trackman Ver. 3e). The body alignment variables were collected using 8 motion capture system. An Independent samples t-test was used for comparison between the Out-to-In group and In-to-Out group, and the statistical significance level was set at .05. Results: For the club head related variables, club path and club face angle showed higher values in Out-to-In swing plane than In-to-Out swing plane. For the kinematic variables of the golf ball, the total distance showed a higher value in the In-to-Out swing plane than that of the Out-to-In swing plane. For the body alignment, the In-to-Out swing plane showed higher values than the Out-to-In swing plane for the pelvis rotation angle and trunk rotation angle. Conclusion: This study suggest that it would be more effective to use the In-to-Out swing plane for increasing the total distance during the golf driver swing.

• Korean Journal of Applied Biomechanics
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• v.17 no.2
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• pp.145-156
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• 2007

The purposes of this study were to investigate kinematic parameters of racket head and upper extremities during squash back hand stroke and to provide quantitative data to the players. Five Korean elite male players were used as subjects in this study. To find out the swing motion of the players, the land-markers were attached to the segments of upper limb and 3-D motion analysis was performed. Orientation angles were also computed for angular movement of each segment. The results were as follows. 1) the average time of the back hand swing (downswing + follow-through) was 0.39s (0.24 s + 0.15 s). 2) for each event, the average racket velocity at impact was 11.17m/s and the velocity at the end of swing was 8.03m/s, which was the fastest swing speed after impact. Also, for each phase, 5.10m/s was found in down swing but 7.68m/s was found in follow-through. Racket swing speed was fastest after the impact but the swing speed was reduced in the follow-through phase. 3) in records of average of joints angle, shoulder angle was defined as the relative angle to the body. 1.04rad was found at end of back swing, 1.75rad at impact and it changes to 2.35 rad at the end of swing. Elbow angle was defined as the relative angle of forearm to upper arm. 1.73rad was found at top of backswing, 2.79rad at impact, and the angle was changed to 2.55rad at end of swing. Wrist angle was defined as the relative angle of hand to forearm. 2.48rad was found at top of backswing, 2.86rad at impact, and the angle changes to 1.96rad at end of swing. As a result, if the ball is to fly in the fastest speed, the body has to move in the order of trunk, shoulder, elbow and wrist (from proximal segment to distal segment). Thus, the flexibility of the wrist can be very important factor to increase ball speed as the last action of strong impact. In conclusion, the movement in order of the shoulder, elbow and the wrist decided the racket head speed and the standard deviations were increased as the motion was transferred from proximal to the distal segment due to the personal difference of swing arc. In particular, the use of wrist (snap) may change the output dramatically. Therefore, it was concluded that the flexible wrist movement in squash was very important factor to determine the direction and spin of the ball.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.2
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• pp.297-304
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• 1997

This paper presents a systematic design method of an anti-swing control law for overhead cranes. A velocity servo system for the trolley of a crane is designed based on the dynamics of the trolley and its load. The velocity servo system compensates for the effects of load swing on the trolley dynamics so that the velocity servo is independent of load swing. The velocity servo system is used for the design of a position servo system for the trolley via the loop shaping method. The position servo system and the swing dynamics of the load are then used to design an angle control system for load swing based on the root locus method. The combined position servo and the angle control systems constitute the overall control system. In the presence of low frequency disturbances, the proposed control law guarantees accurate position control for the trolley and fast damping for load swing. Furthermore, the performance of the proposed control law is independent of the mass of the load. Experimental results on a prototype crane show the effectiveness of the proposed anti-swing control law.

• Journal of International Academy of Physical Therapy Research
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• v.1 no.2
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• pp.162-168
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• 2010

Low back pain is a common phenomenon among the golfers. In an attempt to understand low back pain, the kinematic changes and golf swing motion analysis has been performed to focus on lumbar spine in pro. golfers. According to the swing pattern, significant variations of the lumbar joint forces and loads has related with muscles activities so the motion analysis of lumbar spine were discussed. The purpose of this study was to analyze motion of lumbar spine and it was to compare joint force during golf swing in pro. golfers. The swing motion of the subjects was tracked using a 3D motion analysis system by Motion Analysis Ltd. and SIMM software. The angle changes of lumbar spine rapidly in vx direction during the top back swing and the finish and in vy direction during the follow through and in vz direction during the down swing and the impact(Subject A). The angle changes of lumbar spine rapidly in vx direction during the top back swing and in vy direction during the down swing, the impact and the follow through and in vz direction during the down swing(Subject B). In conclusion, subject A and B both show sudden angle changes between 1st-3rd lumbar spine and 4th-5th lumbar spine during the stage from address to top back swing which caused by over upper body twisting.

• Korean Journal of Applied Biomechanics
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• v.16 no.3
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• pp.85-94
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• 2006

The purpose of this study was to analyze the kinematics variables of during forehand stroke by stance patterns. Eight high school tennis players were chosen for the study, who have never been injured for last six months, in Busan. They performed horizontal swing and vertical swing that it was done each five consecutive trial in the condition of square, open and semi-open stance. It was filmed by 6 video camera and used with 3-dimensional motion analyzer system. The following kinematic variables were analyzed in relation to angle of segment( shoulder, hip and knee joint). The conclusion were as follow: 1. The angle of hip joint represented at impact that horizontal swing was not significant difference by stance patterns but vertical swing was increased in open stance than square and semi-open stance. 2. The angle of both knee was not significant difference between all stance types and swing patterns. 3. The angle of shoulder, hip and knee joint rotation showed that open stance was increased than square and semi-open stance in all swing types and event.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.54 no.3
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• pp.133-138
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• 2005

This paper presents a characteristics of horizontal swing angle in V type suspension string sets for 765kV T/L. The design of V type suspension string set does not differ from that of general string set for general towers, but it prevents instabilities from swing motion by the horizontal angle and by the wind pressure. We were designed specially 6 conductor yoke, arcing horn and earth horn. And we were decided to 550mm for a distance of strings. We were carried out characteristics of horizontal swing test and movement of mass center test for V-string sets of 400kN single, 300kN double and 400kN double. This products will be used for 765kV T/L of 1 circuit in suspension towers.

• Proceedings of the KIEE Conference
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• summer
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• pp.627-629
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• 2004

V type suspension string sets prevent instabilities from swing motion by the horizontal angle and by wind pressure. These installation conditions are controled mainly 3 items - normal swing angle by horizontal angle of line, unusual swing angle by strong wind, minimum vertical loads. We calculated and analysed that factors for the 765kV transmission line condition. And we were tested swing characteristics of V-string sets in real size test situation. So, we find to installation condition for the V type suspension string sets. This results will be used to design of V type suspension string set and to decision of the installation condition.

• Proceedings of the KIEE Conference
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• 2001.04a
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• pp.116-118
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• 2001

It is important to determine of tower type whether suspension or tension tower in overhead transmission lines. When we select to tower type, we have need to check of swing angle for suspension string sets. And jumper wire of T/L in the strong wind area have to analysis of swing angle in order to clearance or length of tower arms. This paper is summarized the methods to calculate of swing angle for suspension string sets and jumper wires, and is calculated the swing angle. The calculated result have proposed to improved design specifications of overhead transmission line.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.9
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• pp.166-171
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• 1999

An overhead crane system consists of trolley, girder, rope, object, trolley motor, girder motor, and hoist motor. An analytic model which derived from the modelling of the overhead crane system is nonlinear model which includes the swing and the twist angle of the object. this model consists of the equation of motion for motors and object. If the swing angle and the acceleration of Z for the object are small, this model becomes a simple nonlinear model which doesn't include the swing and the twist angle of the object. From the results of computer simulation, the characteristics of an actual overhead crane system could be predicted by the simple nonlinear model.