• 한국운동역학회지
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• 제16권3호
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• pp.9-18
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• 2006

These studies show that I applied to functional insole (a specific S company) for minimizing shocks and sprain people's ankle arising from running. How to an effect on human body which studied a kinematics and kinetics from 10 college students during experiments. This study imposes several conditions by barefoot, normal running shoes and put functional insole shoes ran under average $2.0{\pm}0.24$ meter per second by motion analysis, ground reaction force and electromyography that used to specific A company. First of all, Motion analysis was caused by Achilles tendon angle, Angle of the lower leg, Angle of the knee, Initial sole angle and Barefoot angle. Second, Contact time, Vertical impact force peak timing, Vertical active force and Active force timing, and Maximum loading rate under impulse of first 20 percent and Value of total impulse caused Ground reaction force. Third. The tendon fo Quadriceps femoris, Biceps femoris, Tibialis anterior and gastronemius medials caused. electromyography. 1. Ground reaction force also showed that statically approximates other results from impact peak timing (p.001), Maximum loading rate(p<.001), Maximum loading rate timing (p<.001) and impulse of first 20 percent (p<.001). 2 Electromyography showed that averagely was distinguished from other factors, and did not show about that. Above experiment values known that there was statically difference between Motion analysis and Ground reaction force under absorbing of the functional insole shoes which was not have an effect on our body for kinetics and kinematics.

• 한국운동역학회지
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• 제32권1호
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• pp.9-16
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• 2022

Objective: The purpose of this study was to investigate how the chronic ankle instability affects postural control during forward jump landing. Method: 20 women with chronic ankle instability (age: 21.7 ± 1.6 yrs, height: 162.1 ± 3.7 cm, weight: 52.2 ± 5.8 kg) and 20 healthy adult women (age: 21.8 ± 1.6 yrs, height: 161.9 ± 4.4 cm, weight: 52.9 ± 7.2 kg) participated in this study. For the forward jump participants were instructed to stand on two legs at a distance of 40% of their body height from the center of force plate. Participants were jump forward over a 15 cm hurdle to the force plate and land on their non-dominant or affected leg. Kinetic and kinematic data were obtained using 8 motion capture cameras and 1 force plates and joint angle, vertical ground reaction force and center of pressure. All statistical analyses were using SPSS 25.0 program. The differences in variables between the two groups were compared through an independent sample t-test, and the significance level was to p < .05. Results: In the hip and knee joint angle, the CAI group showed a smaller flexion angle than the control group, and the knee joint valgus angle was significantly larger. In the case of ankle joint, the CAI group showed a large inversion angle at all events. In the kinetic variables, the vGRF was significantly greater in the CAI group than control group at IC and mGRF. In COP Y, the CAI group showed a lateral shifted center of pressure. Conclusion: Our results indicated that chronic ankle instability decreases the flexion angle of the hip and knee joint, increases the valgus angle of the knee joint, and increases the inversion angle of the ankle joint during landing. In addition, an increase in the maximum vertical ground reaction force and a lateral shifted center of pressure were observed. This suggests that chronic ankle instability increases the risk of non-contact knee injury as well as the risk of lateral ankle sprain during forward jump landing.

• 한국운동역학회지
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• 제28권2호
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• pp.143-149
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• 2018

Objective: This study aimed to investigate the influence of landing foot orientations on biomechanics of knee joint in order to identify vulnerable positions to non-contact knee injuries during single-legged landing. Method: Seventeen men (age: $20.5{\pm}1.1 years$, height: $175.2{\pm}6.4cm$, weight: $68.8{\pm}5.8kg$) performed single-leg drop landings repeatedly with three different landing foot orientations. They were defined as toe-in (TI) $30^{\circ}$ adduction, neutral (N, neutral), and toe-out (TO) $30^{\circ}$ abduction positions. Results: The downward phase time of TI was significantly shorter than those of N and TO. The flexion and valgus angle of N was greater than those of TI and TO at the moment of foot contact. At the instance of maximum knee flexion, N showed the largest flexion angle, and TO position had the largest varus and external rotation angles. Regarding ground reaction force (GRF) at the moment of foot contact, TO showed the forward GRF, while others showed the backward GRF. TI indicated significantly larger mediolateral GRF than others. As for the maximum knee joint force and joint moment, the main effect of different foot positions was not significant. Conclusion: TI and TO might be vulnerable positions to knee injuries because both conditions might induce combined loadings to knee joint. TI had the highest mediolateral GRF with a shortest foot contact time, and TO had induced a large external rotation angle during downward phase and the peak forward GRF at the moment of foot contact. Conclusively, N is the preferred landing foot orientation to prevent non-contact knee injuries.

• 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.

• 대한물리치료과학회지
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• 제19권1호
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• pp.63-69
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• 2012

Background : The purpose of this study was to investigate the frequency domain characteristics of ground reaction forces during quiet standing on inclined surfaces twenty healthy individuals(10 elderly women $68.78{\pm}3.29$ years and 10 young women $20.90{\pm}0.74$ years) participated. Methods : Subjects stood in quiet stance over a force platform positioned in one of three different fixed positions: flat, down and up. Healthy participants completed with eyes open for 120 s trials. Evaluation of postural control were generally based on the interpretation of center of pressure(COP) time series. The COP have been determined using an experimental setup with 3D kinematic and the ground reaction force system. All the data were expressed means and standard deviation by using SAS package program. Results : SEF 50% were not significant in AP and ML direction according to surface slope of both groups. SEF 95% were showed highest frequency in AP direction on down slope of both groups. MEF were not significant all direction according to surface slopes of elderly women. There was no difference between young and elderly women. Conclusion : Elderly women used to ankle strategy during a quiet stance according to COP perturbation of AP direction showed more expanded than ML direction. SEF 95% were showed highest frequency on down slope in elderly women who showed more used ankle strategy for postural control on down slope.

• 한국운동역학회지
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• 제19권1호
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• pp.87-98
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• 2009

본 연구는 남자고등학생 숙련자와 비 숙련자의 던지기 동작을 역학적으로 비교 분석하기 위해 3차원 영상분석 및 지면반력분석을 수행하였다. 연구 결과 숙련자는 공 던지기 동작의 총 소요 시간이 비숙련자보다 짧게 나타났으며, 숙련자는 (1) 왼발 착지 시 신체중심의 수평속도 (2) 전 구간에서 전완 분절의 수평속도 (3) 착지 시 손 분절의 수평속도가 비숙련자보다 빠르게 나타난 반면, 비숙련자는 (1) 착지이후에 신체중심의 수평속도 (2) 왼발이 지면에 닿는 시점에서 손 분절의 수평속도가 숙련자보다 빠르게 나타났다. 전후경각도에서 숙련자는 전 구간에서 후경자세를 취하는 것으로 나타났으나, 비 숙련자는 릴리즈 전까지는 후경자세를 취하다 릴리즈 순간에서는 전경자세를 취한 형태에서 릴리즈를 하는 것으로 나타났다. 또한 숙련자는 공 던지기 동작에서 (1) 어깨각도 (2) 이지 후 오른발의 착지에서 팔꿈치 각도 (3) 최대수직지면반력 (4) 오른발의 착지 시 최대전후지면반력이 비숙련자보다 크게 나타났다. 이와 같은 결과에서 숙련자는 비숙련자보다 안정된 자세로 신체의 중심을 후방에 위치시키는 후경자세를 유지하고 신체의 중심이동을 부드럽게 전환하는 효과적인 던지기 동작이 이루어짐을 알 수 있다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 추계학술대회 논문집
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• pp.549-550
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• 2006

• 한국운동역학회지
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• 제19권2호
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• pp.273-286
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• 2009

본 연구는 고등학교 여자선수들을 대상으로 3차원 영상분석을 이용하여 스윙시 나타나는 각 신체분절 및 클럽의 직임을 운동학적 및 운동역학적 변인들을 산출하여 성공과 실패시에 대한 중요변인들을 비교 분석함으로써 정량적 자료의 추출과 더불어 정성적 평가를 하는데 목적이 있다. 운동학적 변인으로써 위치변화, 속도, 각도에 대한 3차원 분석과 지면반력에 대한 분석을 하였다. 그 결과 스윙시 클럽헤드는 어드레스와 톱스윙시 전후 이동(X축)이 매우 적게 나타남으로써 안정적 스윙이 유지 되는 것으로 나타났다. 또한 좌우방향(Y)의 신체중심이동속도는 성공적인 스윙 동작 시 실패동작시보다 임팩트시 매우 빠른 속도를 나타냄으로써 운동량 증가에 많은 기여를 하였으며 코킹각은 톱스윙에서부터 임팩트까지의 성공시가 코킹각을 더 크게 풀어 줌으로써 임팩트시 선속도 증가에 영향을 주어 비거리 증가에 유리하게 작용할 것으로 판단된다. 지면반력(GRF)은 전후방(X축)과 좌우방향(Y축)에서 안정적인 지지율로 나타남으로써 성공적 스윙으로 연결된 것으로 나타났다.

• 한국운동역학회지
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• 제26권2호
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• pp.197-204
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• 2016

Objective: The purpose of this study was to analyze the kinematic factors of motion during air pistol shooting. Method: This study aimed to investigate changes in forces during movement and determine the factors that affect changes in force during the first, middle, and last periods of shooting an air pistol. Two ground reaction force systems (force platform), SCATT (a shooting training system), and EMG (electromyogram) to measure the action potentials in the muscles of the upper body were used in this study. Four university air pistol players (age: 19.75 years, height: 175.50 cm, body mass: $69.55{\pm}11.50kg$, career length: $6.25{\pm}6years$) who are training to progress to a higher rank were enrolled. Results: In terms of the actual shooting results, the mean score in the middle section was $42.48{\pm}1.74$ points, higher than those in the first and the last periods when using SCATT. The gunpoint moved 13.48 mm more vertically than horizontally in the target trajectory. With respect to action potentials of muscles measured using EMG, the highest action potentials during the aiming-shooting segments, in order higher to lower, were seen in the trapezius (intermediate region), trapezius (superior region), deltoid (lateral), and triceps brachii (long head). The action potentials of biceps brachii and brachioradialis turned out to be high during grasping motion, which is a preparatory stage. During the final segment, muscle fatigue appeared in the deltoid (lateral), biceps brachii (long head), brachioradialis, and trapezius (intermediate region). In terms of the ground reaction force, during the first period of shooting, there was a major change in the overall direction (left-right $F_x$, forward-backward $F_y$, vertical $F_z$) of the center of the mass. Conclusion: The development and application of a training program focusing on muscle groups with higher muscle fatigue is required for players to progress to a higher rank. Furthermore, players can improve their records in the first period if they take part in a game after warming up sufficiently before shooting in order to heighten muscle action potentials, and are expected to maintain a consistent shooting motion continuously by restoring psychological stability.

• 한국운동역학회지
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• 제23권3호
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• pp.209-218
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• 2013

This study was to perform the kinetic analysis of forward $1\frac{1}{2}$ somersault on the platform diving. Six men's diving players of the Korea national reserve athletes participated in this study. The variables were analyzed response time, velocity, center of mass (COM), angle, center of pressure (COP) and ground reaction force (GRF) of motion. For measure and analysis of this study, used to synchronized to 4 camcorder and 1 force plate, used to the Kwon3D XP (Ver. 4.0, Visol, Korea) and Kwon GRF (Ver. 2.0, Visol, Korea) for analyzed of variables. The results were as follows; Time factor were observed in maximum knee flexion depending on the extent of use at phase 1 of take-off to execute the somersault. This enabled the subject to secure the highest possible body position in space at the moment of jumping to execute the somersault and prepare for the entry into the water with more ease. Regarding the displacement of COM, all subjects showed rightward movement in the lateral displacement during technical execution. Changes in forward and downward movements were observed in the horizontal and vertical displacements, respectively. In terms of angular shift, the shoulder joint angle tended to decrease on average, and the elbow joints showed gradually increasing angles. This finding can be explained by the shift of the coordinate points of body segments around the rotational axis in order to execute the half-bending movement that can be implemented by pulling the lower limb segments toward the trunk using the upper limb segments. The hip joint angles gradually decreased; this accelerated the rotational movement by narrowing the distance to the trunk. Movement-specific shifts in the COP occurred in the front of and vertical directions. Regarding the changes in GRF, which is influenced by the strong compressive load exerted by the supporting feet, efficient aerial movements were executed through a vertical jump, with no energy lost to the lateral GRF.