• 한국운동역학회지
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• 제18권1호
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• pp.147-158
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• 2008

본 연구의 목적은 우수 고등학교 테니스 선수 7명을 대상으로 테니스 서브 스탠스 유형(pinpoint stance, platform stance)에 따른 서비스 동작의 운동학적인 분석을 통하여 빠른 서브를 구사할 수 있도록 지도할 기초자료를 제공하는데 있다. Pinpoint Stance는 백스윙국면에서 뒷발을 앞발방향으로 이동하기 때문에 신체중심(COM)과 라켓의 많은 움직임으로 인해 소요시간이 Platform Stance 보다 0.04초 길게 소요되었다. 발을 이동하면서 골반부위를 앞으로 이동시켜서 몸을 활처럼 많이 휘게 함으로써 백스윙부터 임팩트까지 파워를 낼 수 있는 구간을 넓혀 COM과 라켓의 속도를 빠르게 하여 서브의 속도를 증가시키는데 기여하는 스탠스임을 알 수 있었다. Platform Stance는 백스윙국면에서 발의 이동이 없기 때문에 COM과 라켓의 작은 움직임으로 인해 소요시간이 Pinpoint Stance 보다 0.04초 짧게 소요되었다. 발의 이동이 없어서 파워를 낼 수 있는 구간을 좁혀 COM과 라켓의 속도가 느리게 나타났지만 중심의 안정감을 높여 서브의 성공률을 높이는데 기여하는 스탠스임을 알 수 있었다.

• 해양환경안전학회지
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• 제15권3호
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• pp.223-228
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• 2009

2003년 태풍 매미로 인하여 안전한 피항지로 여겨졌던 진해만에서도 강풍에 의한 주묘로 좌초, 충돌 등 많은 해양사고가 발생하였다. 투묘에 대한 사항이나 주묘를 예측하기 위해서는 외력과 대항력에 대한 비교 검토가 필요하다. 하지만 풍압력에 대한 부분에서 스윙현상으로 인한 풍압면적 적용에 대한 연구가 진행되고 있으나, 여전히 논란의 대상이 되고 있다. 따라서 실습선 한바다호를 대상으로 선체에 작용하는 외력과 외력에 대한 대항력을 수치적으로 계산하고, 이를 실제로 주묘가 발생했던 실선계측자료와 상호 비교 분석함으로써 묘박 중선박에 가해지는 풍압력에 대한 평가를 실시하였다.

• 대한의용생체공학회:의공학회지
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• 제28권2호
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• pp.187-194
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• 2007

The purpose of this study is to determine the characteristics of ground reaction force(GRF) in golf swing for various slopes of flat lie and uphill lies of 5 and 10 degrees. Five right-handed professional golfers were selected for the experiment and the 7 iron club was used. We used four forceplates to measure GRF and synchronized with the three-dimensional motion analysis system. Results showed that slope did not affect the total time for golf swing, but the time until the impact had a tendency to slightly increase for the uphill lie(p<0.05). The medial-lateral GRF of the right foot increased toward the medial direction during back swing, but less increases were found with the angle of uphill lie(p<0.05). The GRF of the left foot increased rapidly toward the medial direction at the uncocking and the impact during down swing, but decreased with the increase in the angle of uphill lie(p<0.05). The anterior-posterior GRF of both feet showed almost the same for different slopes. With the slopes, the vertical GRF of the right foot increased, but the vertical GRF of left foot decreased(p<0.05). Uphill lies would have negative effect to provide the angular momentum during back swing, restricting pelvic and trunk rotations, and to provide the precise timing and strong power during down swing, limiting movements of body's center of mass. The present study could provide valuable information to quantitatively analyze the dynamics of golf swing. Further study would be required to understand detailed mechanism in golf swing under different conditions.

• 대한기계학회논문집A
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• 제29권5호
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• pp.777-785
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• 2005

The swing motion control problem of a container hanging on the trolly is considered in the paper. In the container crane control problem, suppressing the residual swing motion of the container at the end of acceleration, deceleration or the case of that the unexpected disturbance input exists is main issue. For this problem, in general, many trolley motion control strategies are introduced and applied. In this paper, we introduce and synthesize a swing motion control system in which a small auxiliary mass is installed on the spreader made by ourselves. In this control system, the actuator reacting against the auxiliary mass applies inertial control forces to the container to reduce the swing motion in the desired manner. In many studies, the controllers used to suppress the vibration have been synthesized for the given mathematical model of plants. And, the designers have not been able to utilize the degree of freedom to adjust the structural parameters for the control object. To overcome this problem, so called 'Structure/control Simultaneous Method' is used. In this paper, the simultaneous design method is used to determine the optimum weight of moving mass such that the optimal system performance would be achieved. And the experimental result shows that the proposed control strategy is useful to the case of that the controlled system is exposed to the uncertainties and, robust to the unexpected disturbance inputs.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.903-906
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• 2005

The purpose of this study was to analyze the muscular force of swing using the soft golf club in comparison with the muscular force of swing using normal golf club. The subject was normal adult (twenties) and performed swing motion using normal and soft golf club. And then we compared muscular power soft golf club with normal golf club of the subject. The muscular power of the subject was measured by MP 100(BIOPAC Systems, Inc.). For the analysis of muscular power of swing using soft golf club, we measured EMG(Electromyography) of the subject. The position of muscle was deltoid, latissimus dorsi, external oblique and rectus abdominis of the upper limbs and rectus femoris, biceps femoris, gastrocnemius and soleus of the lower limbs. The result of experiment, muscle pattern of swing using soft golf club was similar to pattern of swing using normal golf club and muscular power of subjects using the soft golf was smaller than normal golf.

• 한국운동역학회지
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• 제15권2호
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• pp.41-55
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• 2005

In this study, weight carrying pattern analysis and comparison method of four foot region were suggested. We used three types of club(driver, iron7, pitching wedge). This analysis method can compare between top class golfer and beginner. And the comparison data can be used to correct the swing pose of trainee. If motion analysis system, which can measure the swing speed and instantaneous acceleration at the point of hitting a ball, is combined with this plantar foot force analysis method, new design development of golf shoes to increase comfort and ball flight distance will be available. 1. Regional change of force acting, in address, is evenly distributed on both feet. In back swing top, 76% on right foot, 75% on left foot as impact, and 86% on left foot as finish. As regional force acting, in address, pros get high marks on rare and inside of right foot and rare and outside for amateurs. In back swing top, it is higher as fore and inside of left foot, pros as rare part of right foot and amateurs as forefoot. In impact, it is higher for pros and amateurs in outside and rare part of left foot and fore and inside of right foot. In finish, for both pros and amateurs, it is higher for outside and rare parts of left foot. 2. For each club, forces are evenly distributed on both feet in address. In back swing top, the shorter a club is, the higher impact on right foot and the higher finish distribution on left foot. For all the clubs used, in each region, pros get higher on rare and inside of right foot and as amateurs on rare and outside of left foot in address. In back swing top, for all clubs, pros get higher on rare and outside of right foot as fore and outside for amateurs. In impact acting, for all clubs, rare and outside of left foot get higher. In finish, force concentrates on rarefoot. 3. On both feet force, right foot forces of amateurs is higher than those of pros in back swing top. In impact and finish, pros get higher on left foot.

• 한국운동역학회지
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• 제13권3호
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• pp.133-149
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• 2003

The purposes of present study were to determine the major check-points of golf swing from the review of previous studies, and to suggest additional information on the teaching theory of golf. The golf swing motion of 6 male and female elite university golf players were filmed with 16mm Locam II high speed cameras at the speed of 200f/s, and variables such as time, displacement, angle, velocity were calculated and analyzed by 3D Cinematography using DLT method. The results were: 1. Differences were shown in the ratio of weight distribution on the feet, cocking angle, take-back velocity, club-head velocity at impact depending upon the physical characteristics and club used for swing. 2. Time for the down-swing and impact were $0.27{\sim}0.29s$ in men and $0.29{\sim}0.32s$ in women, which was 1/3 of the time for the back-swing. Women showed longer total swing time than men because of longer time in back-swing, follow-through and finish. 3. Men showed larger range of motion in shoulder and knee joints than women, on the other hand women showed larger range of motion in hip joint than men. 4. Cocking motion and right elbow flexion were occurred at the top of back-swing and cocking release was occurred at the moment of impact. Maximum rotations of shoulder and hip joints were found between the top of back-swing and down-swing phase. 5. Women showed lower back-swing velocity than men, and men showed higher club velocity(men: $38.2{\sim}38.6m/s$, women: $35.1{\sim}36.4m/s$) than women.

• 한국운동역학회지
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• 제21권3호
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• pp.317-325
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• 2011

The purpose of this study was to investigate the contributions of body joints to the kinetic energy of the clubhead in the golf swing. Three dimensional swing analysis was conducted on the seven KPGA golfers. The subjects were asked to swing with 45 inches of driver. The work done by body joints were computed by utilizing the inverse dynamics method. The order of work done by the body joints was lumbar > left hip > right shoulder > left wrist > right wrist > right hip at the first phase. At the second phase, the order of work done by the body joints was trunk > left elbow > right wrist > right shoulder > left wrist > right wrist. At the third phase, the order of work done by body joints was lumbar > right shoulder > left shoulder > left elbow > right wrist > right elbow. The sum of the work done by the body joints was lumbar > shoulder > wrist on the average. The kinetic energy of the club head was 430.11${\pm}$24.35 J and the subject's swing efficiency was shown as 31.82${\pm}$4.86% on the average. The contributions of body joints to the kinetic energy of the clubhead was the order of lumbar > upper right shoulder > left elbow > right wrist during the down swing.

• 한국운동역학회지
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• 제22권3호
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• pp.269-276
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• 2012

The purpose of This study's aim is to examine the difference in the changes of body segment movement, variables for ball quality, and carry at golf driver swing according to the ball quality using comparative analysis. Regarding the impact variables according to the ball quality using the track man and carry, club speed was the fastest at draw shot, ball speed was the fastest at straight shot, and smash factor was the lowest at draw shot. About the vertical launch angle, the fade shot showed the highest launch angle while the max height of the ground and ball was the highest at fade shot. And carry was the longest at draw shot. For the flight time, it was the longest at draw shot. The landing angle was the largest at fade shot. About the club head position change and trajectory, at the overall event point, the fade shot drew a more outer trajectory at the point of the follow through(E6) than the straight or draw shot. Regarding the angular speed of shoulder rotation, at the overall event point, the fade shot showed the greatest angular speed change in the follow through(E6). Also, about the angular speed of pelvic rotation, at the overall event point, the draw shot showed the greatest angular speed change at the point of down swing(E4). Concerning the stance angle change, both straight and fade shots were open as the concept of open stance whereas the draw shot was close as that of close stance. Regarding the previous study, the most important factor of deciding Ball Quality is the club face angle's open and close state at Impact. In short, the Ball Quality and carry were decided by this factor.

• 한국운동역학회지
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• 제20권1호
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• pp.83-90
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• 2010

The purpose of this study is to validate that change of impact by the Early Extension in during a golf driver swing. 13 golf players who were diagnosed with symptoms of Early Extension participated in a proactive corrective training programs that took place 3 times a week for a 4 month period. Data was collected by recording 5 pre and 5 post training driver swings and analyzing the data to calculate the change in velocity and its effect in the shot used the TRACK MAN. After the training, the changes of early extension were -0.21 cm in backswing section E2(take away), -0.64 cm in E3(halfway backswing), and -0.94 cm in E4(backswing top). The downswing section changes were -1.34 cm in event E5(halfway downswing), -1.74 cm in E6(impact). Impact force increased and thus club speed increased by 6.32 km/h, ball speed increased by 10.94 km/h, max height decreased by -6.22 m, carry increased by 10.85 m, carry side(left deviation) decreased by 4.84 m, flight time by increased by 0.4 sec, and total length increased by 17.96 m while landing angle decreased by -7.74 deg.