• Korean Journal of Applied Biomechanics
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• v.15 no.4
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• pp.13-24
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• 2005

The purpose of this study was to compare kinematic data between experts and novices, and identify difference kinematic parameters changing direction to kick in penalty kick of soccer play. Novice subjects were 5 high school students Who has never been experienced a soccer player, and expert subjects were 5 competitive high school soccer players. The 3-d angle was calculated by Euler's Angle by inertial axis and local axis with three-dimensional cinematography. Kinematic parameters in this study consisted of angles of knee joints, hip joints, lower trunk and upper trunk when the support foot was contacted on ground and kicking foot impacted the ball. The difference of angle of knee joints in the flexion/extension was insignificantly showed below $4{\sim}9^{\circ}$ in groups and directions of ball at the time of support and impact. But the difference of angle of hip joint was significant in groups and directions of ball at the time of support and impact. Specially the right hip joint of experts were more flexed about $12^{\circ}$($43.99{\pm}6.17^{\circ}$ at left side, $31.87{\pm}4.49^{\circ}$ at right side), less abducted about $10^{\circ}$ ($-31.27{\pm}4.49^{\circ}$ at left side, $-41.97{\pm}6.67^{\circ}$ at right side) at impact when they kicked a ball to the left side of goalpost. The difference of amplitude angle in the trunk was significantly shown at upper trunk not lower trunk. The upper trunk was external rotated about $30^{\circ}$ (novice' angle was $-16.3{\pm}17.08^{\circ}$, expert's angle was $-43.73{\pm}12.79^{\circ}$) at impact. Therefore the significant difference of kinematic characteristics could be found at the right hip joint and the upper trunk at penalty kick depending on the direction of kicking.

• PNF and Movement
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• v.13 no.2
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• pp.95-102
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• 2015

Purpose: The purpose of this study was to analyze the effect of arm flexion patterns of proprioceptive neuromuscular facilitation on muscle activation in the contralateral lower extremity. Open kinematic chain and closed kinematic chain positions were used. Methods: This study used an electromyogram (MP150, Biopac Systems, USA) to measure muscle activation in 20 healthy male students. Comparative analysis was completed on muscle activation of the vastus lateralis, biceps femoris, tibialis anterior, and gastrocnemius of the contralateral lower extremity. Open kinematic chain and closed kinematic chain positions were used with a unilateral arm flexion-abduction-external rotation pattern. Paired t-tests using the SPSS 12.0 for Windows analyzed the data produced by the electromyogram. Results: There was a statistically significant difference in muscle activation in the biceps femoris, gastrocnemius, and tibialis anterior when the open kinematic chain and closed kinematic chain positions were compared (p < 0.05). Conclusion: The biceps femoris, gastrocnemius, and tibialis anterior muscles showed greater muscle activation in the closed kinematic chain position when compared to the open kinematic chain position.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.1840-1843
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• 1997

The task environment of a robot is changing rapidly and task itself becomes complicated due to current industrial trends of multi-product and small lot size production. A convenient user-interfaced off-line programming(OLP) system is being developed in order to overcome the difficulty in teaching a robot task. Using the OLP system, operators can easily teach robot tasks off-line and verify feasibility of the task through simulation of a robot prior to the on-line execution. However, some task errors are inevitable by kinematic differences between the robot model in OLP and the actual robot. Three calibration methods using image information are proposed to compensate the kinematic differences. These methods compose of a relative position vector method, three point compensation method, and base line compensation method. To compensate a kinematic differences the vision system with one monochrome camera is used in the calibration experiment.

• The Journal of Korean Physical Therapy
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• v.25 no.5
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• pp.297-302
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• 2013

Purpose: This study was conducted in order to investigate the kinematic gait parameter of lower extremities with different gait conditions (level walking, stair, ramp) in hemiplegic patients. Methods: Ten hemiplegic patients participated in this study and kinematic data were measured using a 3D motion analysis system (LUKOtronic AS202, Lutz-kovacs-Electronics, Innsbruk, Austria). Statistical analysis was performed using one-way repeated measure of ANOVA in order to determine the difference of lower extremity angle at each gait phase with different gait conditions. Results: Affected degree of ankle joint in the heel strike phase showed significant difference between level walking and climbing stairs, and toe off phase showed significant difference between level walking and climbing stairs, ramps, and climbing stairs. Affected degree of knee joint showed no significant difference in all attempts. Affected degree of hip joint in the toe off phase showed significant difference between level walking, ramps and stairs, and climbing ramps. Swing phase showed significant difference between sides for level walking and stairs, climbing ramps. Affected ankle joint of heel strike and toe off, and affected hip joint of toe off and the maximum angle of swing phase in the angle was increased. Unaffected side of the ankle joint, knee joint, and hip joint showed a significant increase in walking phase. Conclusion: These findings indicate that compared with level walking, different results were obtained for joint angle of lower extremity when climbing stairs and ramps. In hemiplegia patient's climbing ramps, stairs, more movement was observed not only for the non-affected side but also the ankle joint of the affected side and hip joint. According to these findings of hemiplegic patients when climbing stairs or ramps, more joint motion was observed not only on the unaffected side but also on the affected side compared with flat walking.

• Korean Journal of Applied Biomechanics
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• v.30 no.1
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• pp.17-25
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• 2020

Objective: The purpose of this study is to provide a better understanding of long turn mechanism by describing long turns after kinematic analysis and provide skiers and winter sports instructors with data through which they are able to analyze right postures for turns in skiing in a systematic, rational and scientific manner. Method: For this, a mean difference of kinematic variables (the center of gravity (CG) displacement of distance, trajectory, velocity, angle) was verified against a total of 12 skiers (skilled and unskilled, 6 persons each), regarding motions from the up-start to down-end points for long turns. Results: First, concerning the horizontal displacement of CG during a turn in skiing, skilled skiers were positioned on the right side at the upstart and edge-change points at a long turn. There was no difference in anteroposterior and vertical displacements. Second, in terms of CG-trajectory differences, skilled skiers revealed a significant difference during a long turn. Third, regarding skiing velocity, skilled skiers were fast at the edge-change and maximum inclination points in long turns. Fourth, there was no difference in a hip joint in terms of a lower limb joint angle. In a knee joint, a large angle was found at the up-start point among skilled skiers when they made a long turn. Conclusion: In overall, when skilled and unskilled skiers were compared, to make a good turn, it is required to turn according to the radius of turn by reducing weight, concerning the CG displacement. Regarding the CG-trajectory differences, the edge angle should be adjusted via proper inclination angulation. In addition, a skier should be more leaned toward the inside of a turn when they make a long turn. In terms of skiing velocity, it is needed to reduce friction on snow through the edging and pivoting of the radius or turn according to curvature and controlling ski pressure. Regarding a lower limb joint angle, it is important to make an up move by increasing ankle and knee angles instead of keeping the upper body straight during an up motion.

• Korean Journal of Applied Biomechanics
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• v.29 no.4
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• pp.219-226
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• 2019

Objective: The purpose of this study is to provide a better understanding of short turn mechanism by describing short turns after kinematic analysis and provide skiers and winter sports instructors with data through which they are able to analyze right postures for turns in skiing in a systematic, rational and scientific manner. Method: For this, a mean difference of kinematic variables (ski-hip angle, ski-shoulder twist angle, pole checking angle, the center of gravity (CG) displacement, trunk forward lean angle) was verified against a total of 12 skiers (skilled and unskilled, 6 persons each), regarding motions from the up-start to down-end points for short turns. Results: There was no difference in a ski-hip twist angle. The ski-shoulder twist angle was large at the up-start point while a pole-checking angle was high at the down-end point in skilled skiers. Concerning the horizontal displacement of CG, skilled skiers were positioned on the right side at the upstart point. No significant difference was observed in the trunk forward lean angle. Conclusion: According to the ski-shoulder twist angle and CG horizontal displacement results, the upper body should be kept leant toward the pole. In addition, big turns should be made via edging and angulation. During pole checking, the hand holding the pole should be thrown and released toward a vector direction of the forearm.

• The Journal of Korean Physical Therapy
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• v.31 no.1
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• pp.13-17
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• 2019

Purpose: This study examined the effects of flexible flatfeet on the accuracy of knee joint motions in closed and open kinetic chain tasks. Methods: Twenty-four healthy participants were recruited for this study. The subjects were divided into two groups using a navicular drop (ND) test: flexible flatfoot group (n=12, male: 6, aged $22.00{\pm}2.22years$) and age-matched control group (n=12, males: 6, aged $22.17{\pm}1.53years$). The accuracy of knee motion was measured quantitatively by tracing through the flexion and extension motion of the knee joints in the closed kinetic chain and the open kinetic chain. Results: There was a significant difference in the accuracy index between the groups in closed kinetic chain task, but there was no significant difference in the open kinetic chain task. In addition, there was a significant difference in the accuracy index between the closed kinetic chain and the open kinetic chain task in the flexible flatfoot group. In addition, a significant negative correlation was observed between the ND and accuracy index in the closed kinematic chain task, but there was no significant relationship between the ND and accuracy index in the open kinematic chain task. Conclusion: Flexible flatfeet can affect the accuracy of the adjacent joints, such as the knee joint in the closed kinematic chain.

• Journal of the Korean Society of Physical Medicine
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• v.4 no.2
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• pp.93-100
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• 2009

Purpose：The purpose of this study was to examine the effects of self-controlled knowledge of result (KR) versus the yoked KR on learning of knee joint proprioception. Methods：Forty volunteer subjects (20 men and 20 women) were randomly assigned to each four groups: 1) self-controlled KR in open kinematic chain, 2) yoked KR in open kinematic chain, 3) self controlled KR in close kinematic chain, and 4) yoked KR in close kinematic chain. The difference between the angle of position and reproduction angle was determined as a proprioception error and measured using an angle reproduction test. The subjects in self-controlled groups were provided with feedback whenever they requested it, whereas the subjects in yoked groups were not provided with feedback. The data were analyzed using a one-way ANOVA. Results：The proprioception errors in close kinematic chain groups decreased significantly compared with those in close kinematic chain groups(p<.05). The proprioception errors in the self-controlled group decreased significantly compared with those in yoked groups during acquisition and retention test(p<.05). Conclusion：Self-controlled knowledge of result during open kinematic chain movement is considered to be a good method on motor learning.

• Water for future
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• v.27 no.4
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• pp.123-133
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• 1994

The kinematic and diffusion models using simplified momentum equations of the full dynamic equation have been frequently used for numerical flow simulations, because they have several computational advantages compared to the full dynamic model. In this paper, the more generally acceptable application ranges of the kinematic and diffusion finite difference models were investigated based on three major parameters, which are channel bed slopes So, dimensionless depth increasing numbers Gw at upstream boundary and Froude numbers Fr. The applicable ranges were obtained by comparing the relative magnitudes of the local acceleration, convective acceleration, pressure, gravity and friction terms in the full dynamic equation. In the simulations, a Courant number of 0.5 was used and the channel bed slopes were changed from 0.00001 to 0.05. Also, Froude numbers of 0.1, 0.5 and 0.9 were employed. In this paper, it is indicated that the applicable ranges of kinematic models are increased with increasing of Froude numbers. However, the applicable ranges of diffusion models are decreased with increasing of Froude numbers. Finally, 9 figures were proposed as a guideline in the application of kinematic and diffusion finite difference models based upon the allowable deviation compared to the full dynamic model. With applying the proposed criteria, it is expected that the flow simulations in the channels, streams or rivers are more efficiently achieved.

• Korean Journal of Applied Biomechanics
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• v.20 no.4
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• pp.447-455
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• 2010

The objective of this study was to analyze the difference in kinematic variables for successful and unsuccessful golf putting strokes. The study population included 8 male secondary school golf players who had played golf for over 3 years and whose handicap was 4 or lower. A hole was made on a 5-m-long artificial flat mat for practice, and an environment similar to that of a real green was created. The participants' motions were analyzed through 3D image analysis, and the difference in kinematic variables for successful and unsuccessful putting strokes in the same direction was determined. Data analysis revealed the following findings: The time spent for a segment of putting was the greatest for the backswing segment for both successful and unsuccessful strokes. During address and impact, the both changed to a larger extent. For successful putting strokes, the change in the elbow angle during the downswing was greater for the right elbow than for the left elbow. For both successful and unsuccessful putting strokes, the left shoulder angle increased during the segment from address to the turning point and decreased during the segment from the turning point to impact. In contrast, the right shoulder angle significantly differed between successful and unsuccessful putting strokes only during address. During successful and unsuccessful motions, the swing was executed with the moving displacement of the X-axis of the club head maintained almost constant along a straight light without back and forth movement. In the backswing segment, moving displacement of the Y- and Z-axes was greater in successful strokes than in unsuccessful strokes; however, this difference was very small for the Y-axis. The velocity of the club head for successful and unsuccessful motions significantly differed during address and at the turning point. The highest velocity of the ball was greater for successful than for unsuccessful putting strokes.