• Korean Journal of Applied Biomechanics
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• v.17 no.2
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• pp.207-216
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• 2007

The purpose of this study was to biomechanical analysis Judo's Kuzushi throwing motion in order to increase the effectiveness of Nage-waja(throwing technique). The Tori was a Judo player with 18 years experience(4th degree) while the Uke was a player with 2 years experience(1st degree). The kinematic data was captured using the Vicon motion system (7 cameras) and the kinetics were recorded by force plates(2 AMTI). The following were the results; While leaning to the front the subject's trunk's angle was $14.5^{\circ}$, the lower limbs angle was $23.8^{\circ}$, knee angle was $179.6^{\circ}$ and the vertical reaction of the left leg was 325.42N(BW 0.34) and the right leg was 233.7N(BW 0.47). While leaning back the subject's trunk's angle was $11.3^{\circ}$, the lower limbs angle was $4.1^{\circ}$, knee angle was $1761^{\circ}$ and the vertical reaction of the left leg was 299.53N(BW 0.43) and the right leg was 441.7N(BW 0.64). While leaning to the left the subject's trunk's angle was $30.8^{\circ}$, the lower limbs angle was $2.7^{\circ}$, knee angle was $175.2^{\circ}$ and the vertical reaction of the left leg was 711N(BW 1.03) and the right leg was 9.2N(BW 0.01). While leaning to the right the subject's trunk's angle was $36.5^{\circ}$, the lower limbs angle was $10.4^{\circ}$, knee angle was $175.2^{\circ}$ and the vertical reaction of the left leg was 13.2N(BW 0.02) and the right leg was 694.7N(BW 1.01). While leaning to the left front corner the subject's trunk's angle was $19.8^{\circ}$ (front) and $15.1^{\circ}$ (left), the lower limbs angle was $17.8^{\circ}$ (front) and $2.4^{\circ}$ (left), knee angle was $177.8^{\circ}$ (front) and $173.9^{\circ}$(left), and the vertical reaction of the left leg was 547.4N(BW 0.8) and the right leg was 117.8N(BW 0.17). While leaning to the right front corner the subject's trunk's angle was $15.4^{\circ}$ (front) and $17.7^{\circ}$ (right), the lower limbs angle was $21.1^{\circ}$, (front) and $5.7^{\circ}$ (right), knee angle was $175.5^{\circ}$ (front) and $178.9^{\circ}$(right), and the vertical reaction of the left leg was 53N(BW 0.08) and the right leg was 622.4N(BW 09). While leaning to the left rear corner the subject's trunk's angle was $9.2^{\circ}$ (back) and $13.8^{\circ}$ (left), the lower limbs angle was $2^{\circ}$, (back) and $5.7^{\circ}$ (left), knee angle was $175.5^{\circ}$ (back) and $172.8^{\circ}$(left), and the vertical reaction of the left leg was 698.2N(BW 1.02) and the right leg was 49.6N(BW 0.07). While leaning to the right rear corner the subject's trunk's angle was $8.9^{\circ}$ (back) and $19.6^{\circ}$ (right), the lower limbs angle was ${0.6^{\circ}}_"$ (back) and $3.1^{\circ}$ (right), knee angle was $174.6^{\circ}$ (back) and $175.6^{\circ}$(right), and the vertical reaction of the left leg was 7.2N(BW 0.01) and the right leg was 749.4N(BW 1.09). It was observed that during the Judo motion Kuzushii the range of the COM varied from $26.5{\sim}39.9cm$. It was concluded that the upper body leaned further than the lower body as there was knee extension. There was high left leg reaction forces while leaning to the left and likewise for the right side. It was therefore deduced that the Kuzushi was a more effective throwing technique for the left side.

• Korean Journal of Applied Biomechanics
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• v.12 no.1
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• pp.63-87
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• 2002

The purpose of this study was to analyze the kinematic variables when Uchi-mata(inner thigh reaping throw) performing by Kumi-kata(engagement position, basic hold) types A, B(A: grasping part-behind neck lapel, B: chest lapel) in Judo with three dimensional analysis technique DLT method by videography. The subjects were four male judokas who have been training in Yong-In University(YIU), on Korean Representative level and Uchi-mata is their tokui-nage(favorite technique), the throwing form was filmed on two S-VHS 16mm video camera( 30frame/sec. Panasonic). Kinematic variables were temporal, posture, and COG. The data collection was performing by Uchi-mata. Six good trials were collected for each condition (type A, B) among over 10 trials. The mean values and the standard deviation for each variable were obtained and used as basic factors for examining characteristics of Uchi-mata by Kumi-kata types. The results of this analysis were as follows : 1) Temporal variables The total time elapsed(TE) by Uchi-mata of types A, B were 1.45, 1.56 sec. respectively. Types A shorter than B. 2) Posture variables In performing of Uchi-mata, the range of flexion in type A, left elbow was $45^{\circ}$ and B was $89^{\circ}$ from Event 2(E2) to Event 6(E6). Type A and B were quite different in right elbow angle in Event1(E1). Left shoulder angle of type A was extended and type B was flexed in E4. Both types right shoulder angles were showed similar pattern. Also both hip angles(right/left) were showed similar pattern. When type A performed Uchi-mata the knee-angle of supporting foot showed $142^{\circ}$in the 1st stage of kake phase[KP], and extended to $147^{\circ}$in the 2nd stage of KP. And the foot-ankle angle of supporting foot showed $83^{\circ}$in the 1st stage of KP, and extended to $86^{\circ}$in the 2nd stage of KP. moreover, The knee angle of attacking foot showed $126^{\circ}$in the 1st stage of KP, and extended to $132^{\circ}$in the 2nd stage of KP, and the foot-ankle angle of attacking foot showed $106^{\circ}$in the 1st stage of KP, and extended to $121^{\circ}$in the 2nd stage of KP. When type B performed Uchi-mata the knee-angle of supporting foot showed $144^{\circ}$in the 1st stage of KP, and extended to $154^{\circ}$in the 2nd stage of KP. And the foot-ankle angle of supporting foot showed $83^{\circ}$in the 1st stage of KP, and extended to $92^{\circ}$in the 2nd stage of KP. moreover, The knee angle of attacking foot showed $132^{\circ}$in the 1st stage of KP, and extended to $140^{\circ}$in the 2nd stage of KP, and the foot-ankle angle of attacking foot showed $103^{\circ}$in the 1st stage of KP, and extended to $115^{\circ}$in the 2nd stage of KP. During Uchi-mata performing, type A showed pulling pattern and type B showed lift-pulling pattern. As Kumi-kata types, it were different to upper body(elbow, shoulder angle), but mostly similar to lower body(hip, knee, ankle angle) on both types. 3) C. O. G. variables When the subjects performed Uchi-mata, COG of type A, B up and down in vertical aspect was 71cm, 73.8cm in height from the foot in the 2nd stage of KP. As Kumi-kata types, it were different on medial-lateral direction aspect but weren't different in Kuzushi phase on vertical direction aspect.

• Korean Journal of Applied Biomechanics
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• v.12 no.2
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• pp.179-195
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• 2002

The purpose of this research is to provide a proper model by analyzing the sports biomechanical of physical movements on the basis of the two patterns(open-stance and cross-stance) at the ready-to-start pose. The subjects for this study are composed of five male handball players from P university and five female shooting players from S university. Three-way moving actions at start(right, left, and forward) are recorded with two high-speed video cameras and measured with two Force platforms and a EMG system. Three-dimensional action analyzer, GRF system, and Whole body reaction movement system are used to figure out the moving mechanisms at the start pose. The analytic results of the moving mechanism at the start pose were as follows. 1. Through examining the three-way moving actions at start, I have found the cross-stance pose is better for the moving speed of body weight balance than the open-stance one. 175 degree of knee joint angle at "take-off" and 172 degree of hip joint angle were best for the start pose. 2. The Support time and GRF data shows that the quickest center of gravity shift was occurred when cross-stanced male subjects started to move toward his lefthand side. The quickest male's average supporting time of left and right foot is 0.19${\pm}$0.07 sec., 0.26${\pm}$0.06sec. respectively. The supporting time difference between two feet is 0.07sec. 3. Through analyzing GRF of moving actions at start pose, I have concluded that more than 1550N are overloaded on one foot at the open-stance start, and the overloaded force may cause physical injury. However, at the cross-stance pose, The GRF are properly dispersed on both feet, and maximum 1350N are loaded on one foot.

• Korean Journal of Applied Biomechanics
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• v.12 no.2
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• pp.345-359
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• 2002

The purpose of the study was to provide the fundamental data to instruct athletes through the analysis athletes' movement in javelin. Three athletes in the level of national representative were participated in this study. The study analyzed kinematic variables(lead foot and releasing javelin) through 3-D analysis and obtained the following results. 1. During withdrawal, it is important to maintain of running horizontal velocity. 2. It was showed that throng average height was $84{\pm}3.3%$ and javelin adequative degree, Among the athletes, $S_2$ who had the best record was released the javelin with the fast velocity, but throw the javelin with the less releasing velocity. 3. $S_2$ released after lead foot were completely landed and therefore it is no problem in a kinematic aspect. However, $S_1$ angle was too small. it caused increase of release velocity to be prevented. 4. $S_2$ showing the best result indicated shorter in duration time. Generally, the shorter duration time in release phase showed the longer release distance. Especially $S_1$ and $S_3$ showing the worse result indicated the longer duration time in preparatory phase, causing the breakup of force. Therefore to improve the record, it should be decreased the duration time in preparatory phase. 5. Compared with $S_1$ and $S_3$, $S_2$ showing the best record indicated the higher velocity in center of mass, trunk, upper arm, lower arm and hand That is the higher velocity of upper arm at release leaded the better velocity transfer from upper arm to following lower arm and hand, these action should be considered to be helpful of better record. According to the above conclusion, when the athletic leaders cauch athletes, they should focus on maintaining knee angle, upper body and hip angle in a previous stage of release and throwing angle, throwing height, throwing velocity in a release stage.

• Korean Journal of Applied Biomechanics
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• v.12 no.2
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• pp.259-278
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• 2002

This study divided straight success, pade success and failure with 7male golfers who have experiences more than 3 years, analyzed kinematic factors of golf swing to suggest scientifically. The conclusions were follows. 1) The wrist angle has significant difference in straight success, pade success and failure when swing of every pattern. There is no significant difference in pade success and failure. 2) The body twist angle has no significant difference in straight success, pade success and failure when swing of every pattern. There is no significant difference in pade success and failure. 3) The shoulder joint rotation angle has no significant difference in success, pade success and failure when swing of every pattern. There is no significant difference in pade success and failure. 4) The left hip joint vertical angle has no significant difference in straight success, pade success and failure when swing of every pattern. There is no significant difference in pade success and failure. 5) The hip joint rotation angle has no significant difference in straight success, pade success and failure when swing of every pattern. There is no significant difference in pade success and failure. 6) The trunk angle has no significant difference in straight success, pade success and failure when swing of every pattern. There is no significant difference in pade success and failure. 7 )The left knee joint angle has no significant difference in straight success, pade success and failure when swing of every pattern. There is no significant difference in pade success and failure. This study divided golf swing motion of pattern change in straight success, pade success and failure and analyzed the kinematic factors by 3-dimension cinematography to improve performance. In the future, many researchers have to study kinematic analysis to improve performance in every events.

• Korean Journal of Applied Biomechanics
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• v.12 no.2
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• pp.159-177
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• 2002

The purpose of this study was to investigate the relations between the segments of the body, the three dimensional anatomical angle and the angular velocity of the air born phase and understand the control mechanism of the high-bar movement, the somersault, the double somersault, the double somersault with full twist. For this study seven well trained university gymnastic volunteered, Zatsiorky and Seluyanov(1983, 1985)'s sixteen segment system anatomical model was used for this study. For the movement analysis three dimensional cinematographical method(Arial Performance Analysis System : APAS) was used and for the calculation of the kinematic variables a self developed program was used with the LabVIEW 5.1 graphical profromming(Johnson, 1999) program. By using Eular's equations the three dimensional anatomical Cardan angles of the joint and angular velocity were defined. As a result of this study 1. As the rotation of the body increased in the air born phase the projection angle of the CM of the total increased, this resulted the increased of the max hight of the CM. 2. In three dimensional angular velocity the Z axis(vertical direction) projection angular velocity increased as the rotation of the body increased in the airborn phase, but the Y axis and the X axis projection angular velocity did not show significant differences. 3. As the rotation of the body increased in the air born phase the angular movement of the shoulder and the hip showed significant change. These movement act as the starter in the preparation phase. 4. The somersault angle, the twist angle, the tilt angle of the upper body related to the global reference frame in the releas phase the average somersault angle of the three types of high-bar movement was $57.7^{\circ}$, $38.8^{\circ}$, $39.7^{\circ}$, the average tilt angle was $-1.5^{\circ}$, $-5.4^{\circ}$, $-8.4^{\circ}$, the average twist angle was $13.4^{\circ}$, $10.6^{\circ}$, $23.3^{\circ}$. This result showed that the somersault with full twist had the largest movement.

• Korean Journal of Applied Biomechanics
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• v.12 no.2
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• pp.51-63
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• 2002

This study sought to identify the kinematic characteristics at entrance to the straight course from the curvilinear course in the 200m-track game. For this purpose, this study was conducted for 4 sprinters by setting the 10m-section combined from the curvilenear track to the straight course and shooting them with the camcorder. It was set up to include all the sections of analysis by using the framework of the control point knowing the coordinate of the space and actual analysis was conducted on the motion showing the best records by conducting it for each subject five times. As a result, the following conclusion was drawn: It was found that the subjects showed the average stride of 4.5${\pm}$0.41 times at the 10-meter section and the required time of 1.42${\pm}$0.04sec. They showed the ratio average stride to height of 1.25${\pm}$0.20% and the average speed of 7.06${\pm}$0.19m/s. The displacement in the center of gravity of the human body at the section combined from the curvilinear course to the straight course was moving along the inward course of the curvilinear course, and the displacement of the leg located at the outward direction(right) was found to be larger than that of the leg located at the inward direction(left). In the speed of the left and right hand segments, it was found that the speed of the right hand located in the outward direction was faster than that of the left hand located at the inward, and it was found that the subjects progressed in the curvilinear course. The subjects showed the larger angle of the shoulder joint when the upper arm was located in the forward direction than when the it was located in the backward direction. In the curvilinear course, they showed the lower value of the lateral angle of the trunk when the right foot located at the outward direction left the ground than when the left foot located at the inward direction left the ground. And it was found that the lateral angle of the trunk became lower with approaching the straight course.

• Korean Journal of Applied Biomechanics
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• v.12 no.2
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• pp.143-157
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• 2002

This study was to analyze the kinematic variables when the subjects performing Uchi-mata(inner thigh reaping throw) by Kumi-kata types((How to grasp A or B?) and two different opponent's height in Judo. Kinematic variables were temporal, posture. Data analysis was collective comparison of two-way ANOVA, t-test by type A&B and two different opponent's height. There were significant difference of Kumi-kata types(p<.05) in the time elapsed on Kake phase(KP : throwing phase) and hip, knee, ankle-angle of the attacking foot in the 1st stage of KP and knee, ankle-angle of the attacking foot and hip, knee ankle-angle of the supporting foot in the 2nd stage of KP. There were significant difference of two opponent's(p<.05) in the time elapsed on KP and hip-angle of the supporting foot in 1st stage of KP. Therefore, the interaction effect(p<.05) were in the time elapsed on KP and hip-angle of the supporting foot in the 2nd stage of KP. So, It could be suggested that Judoka hold on the part-behind neck lapel(type A) at the sleeve with the other of Judogi jacked when opponent's height was short. Because the time elapsed on KP of type B was not so fast as type A(p<.05) during performed Uchi-mata, and also the bigger hip-angle of the supporting foot in the 2nd stage of KP grew, the faster the time elapsed on KP became.

• Korean Journal of Applied Biomechanics
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• v.12 no.2
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• pp.17-32
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• 2002

The purpose of this study was to find the rational method to analyze golf swing with specific property of club shaft. Three subjects were filmed by two high speed digital cameras with 500 fps. The phase analyzed was downswing of each subject. The three-dimensional coordinates of the anatomical landmarks were obtained with motion analysis system Kwon3d 3.0 version and smoothed by lowpass digital filter with cutoff frequency 6Hz. From these data, kinematic and kinetic variables were calculated using Matlab(ver 5.0) The variables for this study were angular velocity and accelerations, which were calculated and following conclusions have been made : 1) Golf swing time of stiff club is faster than that of regular club. 2) In shoulder joint motion of swing with the stiff club, x-stiff showed mort rapid negative acceleration than that of regular club. 3) In regular club, the velocity of club head would be more effective velocity, which was increasing, than those of other clubs before impact. 4) In wrist joint motion of swing with stiff club, x-stiff club showed faster than regular club in the downswing and impact more rapid negative acceleration.

• Korean Journal of Applied Biomechanics
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• v.12 no.2
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• pp.91-107
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• 2002

This research got the following conclusion as result that analyzed high clear action kinematically to 4 C girls' junior high school badminton players who are situated in Chungchong-bukdo. 1. Most of the subject didn't rotate their right shoulder and elbow joint at back swing and moved speedy to shuttle cock. And an cooperation action of joint decreases displaying only a good action on both subject`s specification joint part. 2. When the subject S1 and S2 swing slowly and largely the joint of shoulder and elbow and then the speed of right wrist and racket head is fast, the cooperation action of joint is better than other subject. 3. An angle change of right shoulder showed angle that all subjects are great being caused in softness of joint and angular velocity was exposed that load enough Impact force and increase the speed of racket head as angular velocity decreases rapidly in Impact except subject S3. 4. All subjects of right elbow angle change showed similar form and was exposed that subject S2 sees form of impact stage serious bends from back swing and do not use force effectively in angular velocity. 5. Angle of right wrist appeared that the speed of shuttle cock is decelerated because fast bends of wrist is not formed shortly after Impact because all subject do not accomplish big angle shortly after back swing. Angular velocity can assume that the subject S1 and S4 are using and move fast strong snap shot offering angular velocity value of Impact stage sound (-). 6. While size of Impact stage knee angle accomplishes angle that is big both subject, hip joint angles sees small angle and is playing swing that do on upper body and arm without using strong waist force that is composition action with knee and hip joint.