• Korean Journal of Applied Biomechanics
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• v.12 no.1
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• pp.31-46
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• 2002

The purpose of this research is to provide scientific training guides and the basis for preventing injuries in performing tango backward walk by comparing the effects the height and shape of a heel will have on leg muscles and determining the difference between skilled and unskilled dancers through EMG analysis according to different types of shoes Total eight female athletes were selected for this research. Four with six years of professional dancing experience and another four with one year of dance sports experience. Utilizing the EMG system, rectus femoris, biceps femoris, anterior tibialis, gastrocnemius were measured under different heights (0cm, 5cm, 7cm, 9cm) and shapes (flat, fine, wide) of a heel. Experiments were conducted calculating EMG peak value and muscle load ration under different types of shoes in order to analyze the EMG of leg muscles and Erector Spinae when performing tango backward walk. The result was as follows: 1. The EMG peak value of leg muscles showed significant difference under different heights of a heel in anterior tibialis(p<.001) and gastrocnemius(p.<01) in case of skilled dancers, and in biceps femoris(p.<01) in case of unskilled dancers. 2. The EMG peak value of leg muscles showed significant difference under different shapes of a heel in anterior tibialis(p<.001) and gastrocnemius(p<.001) in case of skilled dancers, and showed no significant difference in case of unskilled dancers. 3. The muscle load ration of leg muscles showed different degrees of muscle contribution between skilled and unskilled dancers. The muscle load ration was in the order of anterior tibialis, rectus femoris, biceps femoris, and gastrocnemius in case of skilled dancers and anterior tibialis, gastrocnemius, biceps femoris, and rectus femoris in case of unskilled dancers.

• Clinics in Shoulder and Elbow
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• v.5 no.2
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• pp.110-117
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• 2002

Purpose: We compared the results of open and arthroscopic Bankart repair in traumatic recurrent anterior dislocation ,3f the shoulder. Materials and methods: We analysed 7 cases underwent open Bankart repair (group I) and 13 cases underwent arthroscopic Bankart repair (group Ⅱ). The average follow-up period was 68.1 months (51-113 months) in group I and 41.1 months (16~57 months) in group Ⅱ. All patients in group I and Ⅱ were non-athletes. We analyzed statistically objective evaluation, such as the stability of shoulder joint, the range of motion, pain, impaired throwing, Bankart rating system by Rowe and subjective evaluation, visual analog scale (VAS) between two groups. Results: In terms of dominant and non-dominant shoulders, the age at initial episode of dislocation, the elapsed time from injury to surgery, the number of preoperative dislocations associated with susceptibility to apprehension. respectively, there was no statistically significant differences between two groups. In group I the average Rowe's scortls was 84.3 and 3 cases (43%) had excellent results,4 cases (S7cfo), good ones. In group H the average Rowe's scores was 87.3 and 7 cases (54%) had excellent results,6 cases, good ones. There was tendency to show more excellent results in group ll, but there was no statistically significant differences. The average VAS were 90.3 points in group I and 88 points in group Ⅱ, which showed also no statistically significant differences. Conclusion: Open and arthroscopic Bankart repairs had no significant difference and showed also good results in travinatic recurrent anterior dislocation of shoulder.

• Korean Journal of Applied Biomechanics
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• v.15 no.1
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• pp.127-142
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• 2005

The purpose of this study was to analysis biomechanics of the lower extremities injury the heights(40cm, 60cm, 80cm) of jump box as performed depth jump motion by 6 females aerobic athletes and 6 non-experience females students. The event of depth jump were set to be drop, landing and jump. The depth jump motions on the force plate were filmed using a digital video cameras, and data were collected through the cinematography and force plate. On the basis of the results analyzed, the conclusions were drawn as follows: 1. The landing time of skill group was shorter than unskill group at 40cm, 60cm drop height during drop-landing-jump phase especially. The landing time of 60cm drop height was significant between two group(p<.05). 2. The peak GRF of sagittal and frontaI direction following drop height improve was variety pattern and the peak vertical force of 40cm drop height was significantly(p<.05). 3. The magnitude of peak passive force was not increase to change the drop height. 4. The peak passive forces was significant at 40cm drop height between two groups(p<.05)

• Journal of the Korean Academy of Clinical Electrophysiology
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• v.9 no.1
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• pp.35-39
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• 2011

Purpose : The purpose of this study was to determine changes in muscle activity due to elastic taping at the rectus femoris, biceps femoris and tibialis anterior muscles using surface electromyography analysis. Methods : In this study 10 healthy university students in the Department of Taekwondo Studies were screened and individuals with a history of previous injury or surgery to their nerve, muscle, and skeletal systems, such as paresthesia and motor disorder, were excluded. Subjects were taped over the rectus femoris, biceps femoris, and tibialis anterior and their muscle activities were analyzed using the surface electromyography method during maximal voluntary isometric contraction. Results : The results of this study were as follows: muscle activities indicated a significant increase after elastic taping than before at the rectus femoris, biceps femoris, and tibialis anterior muscle. These results lead us to the conclusion that muscle activity were influenced by elastic taping at the rectus femoris, biceps femoris, and tibialis anterior muscles. Conclusion : The results of this study show that muscle activity can be improved by elastic taping at the lower limbs. These results suggest that elastic taping of muscles in the lower extremities has the capability to increase muscle activity in the body.

• Korean Journal of Applied Biomechanics
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• v.21 no.5
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• pp.561-571
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• 2011

The purpose of this study was to perform the kinematic analyses of the women's pole vault skills in IAAF World Championships Daegu 2011. Subjects were the 1st through 8th place finishers in the pole vault. The kinematic analyses were divided into four phases: two dimensional run up analysis, and three dimensional analyses for the remaining plant, swing up, and extension phases. Run-up variables consisted of run up distance, number of steps, average step length, ratio of step length to height, average velocity at the final 5~10 m, approach position. Three variables were analyzed during plant: pole angle, center of gravity (COG) velocity, and COG takeoff angle. Swing up phase variables included: pole flection angle, COG velocity (horizontal, vertical, resultant), COG trajectory and bar approach angle of COG. Compared to the 2009 World Championships in Berlin, the average vault height increased, while run up velocity and approach position were almost unchanged. However, horizontal velocity during the last two steps of the final approach decreased noticeably compared to speeds from 1990. These results reflect the change in both technique and physical fitness in pole vaulters. During extension, the peak height of COG surpassed the clearance height by an average of 0.11m. These specific results can help coaches and athletes modify training and improve performance.

• Korean Journal of Applied Biomechanics
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• v.21 no.5
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• pp.551-560
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• 2011

The purpose of this study was to perform the kinematic analyses of the men's pole vault skills in IAAF World Championships Daegu 2011. Subjects were the 1st through 8th place finishers in the pole vault. The kinematic analyses were divided into four phases: two dimensional run up analysis, and three dimensional analyses for the remaining plant, swing up, and extension phases. Run-up variables consisted of run up distance, number of steps, average step length, the ratio of step length to his height, average velocity at the final 6~11 m, approach position. Three variables were analyzed during plant: pole angle, center of gravity (COG) velocity, and takeoff angle of COG. Swing up phase variables included: pole flexion angle, COG velocity (horizontal, vertical, resultant), COG trajectory and bar approach angle of COG. Compared to the 2009 World Championships in Berlin, the average vault height, run up velocity and approach position increased. However, horizontal velocity during the last two steps of the final approach decreased dramatically compared to speeds from 1990. These results reflect the change in both technique and improved physical fitness in pole vaulters. During extension, the peak height of COG averaged 0.3m higher then COG height when the pole was released. These specific results can help coaches and athletes modify training and improve performance.

• Korean Journal of Applied Biomechanics
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• v.22 no.1
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• pp.55-63
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• 2012

The purpose of this study was to investigate the balance differences between skilled players and less-skilled players during Hakdariseogi motion of Keumgang Poomsae in Taekwondo. To achieve the study goal, total of 10 Taekwondo athletes; 5 skilled players(S, body mass: $67.0{\pm}5.7$ kg, height: $174.0{\pm}4.8$ cm, age: $20.0{\pm}2.0$ yrs) and 5 less-skilled players(LS, body mass: $73.0{\pm}4.9$ kg, height: $176.4{\pm}6.1$ cm, age: $20.8{\pm}1.3$ yrs) participated in this study. A three-dimensional motion analysis with 8 infrared cameras and one force plate whose sampling frequency as 30 Hz and 300 Hz, respectively, were performed. Participants' motion were divided into three phases which were preparation phase(P1), performing phase(P2) and maintaining phase(P3). The range and velocities of COP, the range and RMS of ground reaction torque and displacement between COM and center of BOS of each phase were computed. In this study, at P1 and P3 which were double and single stance, respectively, the range and M-L velocities of COP revealed significantly higher in LS compared with those of S(p<.05). At P2 which was single stance, LS indicated significantly higher in range of COP and ground reaction torque, and M-L velocities of COP than those of S(p<.05). The significantly shorter displacement between COM and center of BOS, however, was found in LS compared with that of S(p<.05). The results from our study indicated that S revealed more stable performance and a better posture control ability during performing Hakdariseogi motion.

• Korean Journal of Applied Biomechanics
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• v.20 no.2
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• pp.149-154
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• 2010

Intentional draw and fade shots could be good weapons for lowering golf score. But how to make such shots? To investigate deterministic variables generating different projectile paths of shots in square stance was the purpose of this study. Ten right-handed male collegiate athletes, showing 1.3 of averaged handicap, participated in this study. They were asked to intentionally perform three different shots such as the straight shot(control condition), draw shot, and fade shot. Swing path, pelvis rotation angle, thorax rotation angle and left forearm supination angle were determined for dependent variables on impact event at each trial. For statistical analysis one-way repeated measures ANOVA were used. The results showed that swing path was one of main factor making differences among three kind of shots. Straight shot vs. Draw shot, Straight shot vs. Fade shot and Draw shot vs. Fade shot showed differences on swing path. And left forearm supination angle revealed significant difference between draw shot and fade shot, showing a significant larger angle of draw shot than fade shot. No other significant difference was detected for the other variables. We found that the shot characteristics were influenced primarily by swing path and left forearm supination angle.

• Journal of Korean Orthopaedic Sports Medicine
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• v.1 no.1
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• pp.75-78
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• 2002

Avulsion of the hamstring tendon from the ischial tuberosity is common in many sports, especially with younger athletes. The injury results from a sudden forceful flexion of the hip joint when the knee is extended and the hamstring muscles powerfully contracted. Early diagnosis and surgical repair with reattachment of avulsed muscles to the ischial tuberosity restore function and correct deformity. But, a delay in the diagnosis and treatment leads to a poor result functionally and clinically. Complication, such as heterotopic ossification and failure of the fixation, etc., were reported following a surgical procedure for this injury. However, sciatic nerve injury has not been reported in the literature. We report our experience of a sciatic nerve palsy after surgery that was performed three months after that the initial injury.

• Korean Journal of Applied Biomechanics
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• v.23 no.2
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• pp.109-116
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• 2013

The purpose of this study was to provide fundamental information for the enhancement of performance through kinematic analysis of cornering according to the radius of curve course in short track speed skating. To perform this study, six skaters: three narrow radius players(N, body mass: $56.0{\pm}7.2$ kg, height: $163.7{\pm}5.1$ cm, age: $21.3{\pm}1.5$ yrs) and three wide radius players(W, body mass: $61.0{\pm}9.5$ kg, height: $169.0{\pm}4.4$ cm, age: $20.0{\pm}1.7$ yrs). Three-dimensional motion analysis was performed on the section from the forth block starting to show the change of radius to the sixth block using eight infrared cameras(sampling frequency of 100 Hz for N and W players). The time of push-off was greater for N than for W(p<.05) while the radius of center of mass was greater for W than for N(p<.05). The flexion and extension of knee and hip joint were greater for N than for W(p<.05). The external rotation of left knee joint was greater for N than for W(p<.05). Based on the findings, a small radius by increasing the range of the flexion and extension of knee and hip joint with greater external rotation of left knee joint would be related to more efficient run at curve. It is expected that these results will be useful in developing a training program for enhancing performance of short track speed skating athletes.