프로와 아마추어골퍼의 스윙 평면 비교연구

장재관(Chang Jae-Kwan),여홍철(Yeo Hong-Chul) 한국체육과학회 2009 한국체육과학회지 Vol.18 No.1

The purpose of this study was to investigate the planar motion of the shaft in a golf swing and any differences between professional and amateur golfers. Four subject golfers were participated and the swing motions with s driver were videotaped and analyzed using three-dimensional techniques. The results can be summarized as follows. The distance from the shaft plane to hozel at address was 0.00㎝ and was raised up at top of the back swing with 62.15㎝, 46.56㎝, 96.04㎝ and -81.98㎝ respectively. This result was contradicted what Cochran & Stobbs's asserted as the golf club head and hand did move in a single plane during a golf swing. The hozel trajectory showed a similar shape with professional golfers but not with amateurs golfers. At P7 which was the impact position the shaft angles were more steeper than the address position with three out of four subjects.

골프 스윙 시 클럽헤드의 평면운동에 관한 고찰

장재관(Chang, Jae-Kwan),류재균(Ryu, Jae-Kyun) 한국체육과학회 2011 한국체육과학회지 Vol.20 No.5

The golf swing had been investigated mathematically with least mean square error method whether the club head could be swung in a single inclined plane. The recent findings suggest that the club head trajectory did not fit exactly to a single plane but could consider its motion as a plane with minor errors. The purpose of this study was to verify whether a single plane could be fitted to club motion with singular value decomposition method. Six professional golfers were participated and the swing movements with driver were analyzed by three-dimensional analysis techniques. The results can be summarized as follows. The orthogonal distances errors from the fitted plane to the center of the club head were shown between 2.6cm and 7.2cm. By considering Cochran & Stobbs"s assertion that 30 yards driving distance reduction with 1.8m mishit from the sweet spot the average distance error from the fitted swing plane to the club head center was 4.23cm at impact and the error could lead the club head mishit the sweet spot. As a result the club head trajectories were not fitted to a single plane.

세계랭킹에 영향을 주는 골프 경기력 요인 분석

장재관(Chang Jae-Kwan),여홍철(Yeo Hong-Chul) 한국체육과학회 2008 한국체육과학회지 Vol.17 No.4

The purpose of this study was to investigate professional golfer's technical factors which influenced to the official world golf ranking. The subjects were professional golfers who were ranked within 63th in the official world golf ranking in 2007. The research assumptions were as following, First, there would be a correlation between golf's technical factors and world ranking. Second, there would be some notable differences in golf's technical factors which would effect to 5 groups differently. The results could be summarized as follows. The average driving distance was 291.20 yards and the average scoring average was 70.01. The world golf ranking had a meaningful correlation both the putt per round and scoring average. The short game ability which was putt per round and scoring average was the key factor which influenced to the official world golf ranking. The scoring average factor had a meaningful effect less than 1% in the statistics level on the official world golf ranking. Performance Statistics are unlikely to able to predict the better performers in the official world golf ranking.

골프 스윙 시 클럽 헤드의 운동에너지에 대한 신체 분절의 기여도

장재관 ( Jae Kwan Chang ),류지선 ( Ji Seon Ryu ),윤석훈 ( Suk Hoon Yoon ) 한국운동역학회 2011 한국운동역학회지 Vol.21 No.3

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±24.35 J and the subject`s swing efficiency was shown as 31.82±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.

다운 스윙시 프로골프 선수들의 스윙평면에 관한 고찰

장재관(Chang, Jae-Kwan),류재균(Ryu, Jae-Kyun) 한국체육과학회 2014 한국체육과학회지 Vol.23 No.6

The golf swing has been investigated mathematically with least mean square error method whether the club head can be swung in a single inclined plane. The recent findings suggest that the club head do not move exactly in a single plane because of the minor errors at the beginning of the downswing. The aims of this study were to verify when the club head begun to the regression plane during the downswing. Four professional golfers were participated and the swing movements with 5 iron were analyzed by three-dimensional analysis techniques. The results can be summarized as follows. The orthogonal distances from the regression plane to the center of the club head were shown between 0.055m and 0.112m above the plane at position 2. So the golf instructor"s assertion that the extended line of the shaft pointing the ball flight line at position 2 was not correct. The angles of the right elbow at the top the back swing were shown between 83.6˚ and 89.2˚ for the participants so that the golf instructor"s assertion with 90˚ at the top of the back swing was supported. The conclusion was that the motion of club head during the downswing was not fitted to a single plane.

PGA 투어 선수들의 경기력 요인들이 평균타수와 상금획득에 미치는 영향

장재관(Chang, Jae-Kwan) 한국체육과학회 2014 한국체육과학회지 Vol.23 No.3

The purpose of this study was to investigate PGA professional golfer`s performance factors which influenced to the scoring average and money leader. The subjects were top one hundred eight money leaders of US PGA tour in 2013. The t-test and stepwise regression analysis of SAS 3.0 with significant (p<.05) were conducted to examine eight PGA professional golfer`s performance factors. The results could be summarized as follows. The PGA group players showed better performance in scoring average and money earning. The PGA group was influenced by sand save percentage, stroke gained in putting and driving accuracy while the WEB.com group was influenced by green in regulation, scrambling and money leader on scoring average. The PGA group was influenced by scoring average and stroke gained in putting while the WEB.com group was influenced by scoring average, green in regulation and scrambling on money leader.

골프 스윙시 하지의 운동역학적 분석

장재관 ( Jae Kwan Chang ),류재균 ( Jae Kyun Ryu ) 한국운동역학회 2014 한국운동역학회지 Vol.24 No.4

The purpose of this study was to investigate joint torques of lower body segments on professional golfers. Three dimensional swing analysis was conducted on the seven subjects. Each subject was asked to swing with 45 inches of Callaway driver, where two force plates (9286AA, Kistler, Switzerland) were built, with his normal speed and tempo. The resultant joint moments of the lower extremities were computed using the kinematic variables of the segments, anthropometric measures and the ground reaction force data by inverse dynamics method. Based on the results of this study, the following conclusions were drawn; It was found that the left ankle joint torque at 3rd phase was increased toward extension on the X-axis and abduction on the Y-axis. The left knee joint torque was alternated from flexion to extension direction in order to lower down the body weight at the beginning of the downswing. The lumbar joint torque was alternated from flexion to extension in order to speed up the upper body rotation which could increase the club head speed ultimately

세계 정상급 여자 허들 선수들이 사용하는 허들 넘는 기술의 운동학적 분석

류재균 ( Jae Kyun Ryu ),장재관 ( Jae Kwan Chang ) 한국운동역학회 2011 한국운동역학회지 Vol.21 No.2

The purpose of this study was to evaluate the kinematic characteristics of 5th hurdle clearance during the 100m hurdle final competition at the 2010 Colorful DaeGu pre-championship meeting. This study was also intended to provide the technical data for better performance for preparing the 2011 world championship. Lee and Jung need to change technical movement by reducing the distance of the take-off point from the hurdle and by decreasing the vertical velocity of the C.G.(center of gravity) at the takeoff. Powell`s angle of the take-off leg showed bigger at the touchdown and smaller at the takeoff comparing to Lee`s and Jung`s. Furthermore, Powell`s horizontal velocity of the C.G. was maintained at the takeoff and touchdown. So, Lee and Jung need to change angle of the take-off leg the same as Powell`s. Both Lee and Jung need to increase the angle of landing leg at the touchdown. In addition to increasing the angle Jung needs to improve the knee and ankle velocity with the hurdling leg.

남자 고등부 포환던지기 선수들의 연도 별 기록에 따른 글라이드와 딜리버리 국면의 운동학적 차이

박재명 ( Jae Myoung Park ),장재관 ( Jae Kwan Chang ),김태삼 ( Tae Sam Kim ) 한국운동역학회 2013 한국운동역학회지 Vol.23 No.4

The purpose of this study was to provide high school male shot putters training methods of gliding and delivery motion through comparative analysis of kinematic characteristics. To accomplish this purpose, three dimensional motion analysis was performed for the subjects(PKC, KKH, YDL) who participated in high school male shot putter competition on 92nd (2011), 93rd (2013) National Sports Festival. The subjects were filmed by four Sony HXR-MC2000 video cameras with 60 fields/s. The three-dimensional kinematic data of the glide, conversion and delivery phase were obtained by Kwon3d 3.1 version. The data of the shoulder rotational angles and projection angles were calculated with Matlab R2009a. The following conclusions had been made. With the analysis of the gliding and stance length ratio, the gliding length was shorter at the TG than the SG with short-long technique but the gliding and stance length ratio was 46.8:53.2% respectively. The deviation of the shots trajectory from APSS(Athlete-plusshot-system) revealed that the PKC showed similar to “n-a-b-c-I” of skilled S-shape type, KKH and YDL showed “n-a-d-f-I`” of unskilled type. Furthermore, they showed smaller radial distance from the central axis of the APSS and the shots were away from the linear trajectory. From this characteristics, The PKC who performed more TG than SG had shorter glide with S-shape of APSS(skilled type) showed the better record than others with technical skill. But KKH and YDL had bigger glide ratio with “na-d-f-I`” of unskilled type and improved their records with technical factor. The projection factor had an effect on the record directly. Because PKC maintained more lower glide and transition posture with momentum transfer through COG`s rapid horizontal velocity respectively the subject possessed the characteristics of high horizontal and vertical velocity with large turning radius from shot putter to APSS.

여성 노인과 성인의 보행안정성 비교

이재훈 ( Jae Hoon Yi ),장재관 ( Jae Kwan Chang ) 한국운동역학회 2014 한국운동역학회지 Vol.24 No.3

The purpose of this study was to investigate the different patterns of the lower limb between elderly and adult females to reduce the rate of falls. Ten old females(age: 73.1±2.69 yrs, height: 151.9±4.82 cm, mass: 57.36±5.36) and ten adult females(age: 28±4.76 yrs, height: 160.6±6.83 cm, mass: 53.9±8.44) were participated in this experiment. The gait motions were captured with Qualisys system and variables were calculated with Visual-3D. The following results were found. The elderly female group showed bigger inclination angle between COM and COP than the adult female group so that the dynamic stability was reduced in walking for the compensation with a bigger stride width. The elderly female group ensure for the necessary forward movement of COM in order to replace the decreased function of ankle and knee joint. If the distance between COM and COP is closer and the energy reduction of a specific joint is reduced, they could prevent the elderly female``s falling rate by strengthening of muscles which were related the extension of ankle joint.