• Korean Journal of Applied Biomechanics
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• v.16 no.2
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• pp.135-144
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• 2006

This study was to investigate the kinematic analysis to score of the Yurchenko stretch skill according to phases in a horse vaulting. For this study, 8 male national gymnasts were participated in acquiring three dimensional kinematical imagining data with four Sony PD-150 video cameras After digitizing motion, the Direct Linear Transformation(DLT) technique was employed to obtain 3-D position coordinates. The kinematic factors of the distance, velocity and angle variable were calculated for Kwon3D 3.1. The following conclusions were drawn; 1) The COG resultant velocity of the less skilled group decreased in PRF phase because the less skilled group had a larger flexion-knee angle than the skilled group in BC phase, Because the less skilled group had larger flexion-shoulder angle than the skilled group in HTO phase, At blocking movement, the body inclined a moving direction. By means of it, COG lowered 2) The skilled group had a more rapid COG's vertical velocity than the less skilled group at HTD and HTO event in HC phase, because this was performed the blocking movement with body angle and contacted on a horse vaulting small and its time short by means of contacting hands on a horse vaulting quickly. Such blocking movement made the vertical up-flight movement easy at POF phase bringing out rapid COG's vertical velocity after take off a horse vaulting.

• Korean Journal of Applied Biomechanics
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• v.15 no.4
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• pp.131-142
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• 2005

This study was investigated the stability of the AK amputee gait through analysing the variability on kinematic variables between the sound leg and the prosthetic limb. The one male, AK amputee who could walk for himself with his prosthetic limb was participated in this study. Six cameras of the MCU 240 and the QTM(Qualisys Track Manager) software were used for data collecting in this study. The relative angle of both segments was the difference between the absolute angle of the distal segment and the absolute angle of the proximal segment. The coupling angles between the prosthetic limb and the sound leg were caculated on the thigh Flexion/Extension in relative to the shank Flexion/Extension and the shank Flexion/Extension n relative to the foot Flexion/Extension. In order to evaluate the variability of segment and joint angle, C.V. was used, and to evaluate the variability for coupling angles, the Relative motion calculated by vector coding method of the continuous methods was used. As stated, the gait pattern of the prosthetic limb was almost similar gait pattern of the sound leg, but the prosthetic limb showed that the gait pattern of the sound leg and the prosthetic limb were not stable against the sound leg.

• Korean Journal of Applied Biomechanics
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• v.20 no.2
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• pp.213-219
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• 2010

The purpose of this study is developing a method to analyze and evaluate a golf swing motion using the ground reaction force (GRF) data. Proper weight shifting is essential for a successful shot in golf swing and this could be evaluated by means of the forces between the feet and ground. GRF during the swing were measured from 15 low-handicapped male golfers including professionals. Four clubs(driver, iron 3, iron 5, and iron 7) were selected to analyze the differences due to different characteristics of club. Swings of each subject were taken using a high speed video camera and GRF data were taken simultaneously by two AMTI force platforms. To simplify the GRF data, forces of the three major component of GRF(vertical, lateral, anterior-posterior force) at 10 predefined temporal events for each trial were selected and the mean of each event were calculated and evaluated. Analyzed vertical GRF (VGRF) data could be divided into two different styles, one-legged and two legged. One-legged style shows good weight transfer to the target leg and most of the previous study shows this style as a typical pattern of good players. Therefore the data from the iron 5 swing obtained from 10 one-legged style golfers are provided as criteria for the evaluation of a swing.

• Korean Journal of Applied Biomechanics
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• v.13 no.2
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• pp.161-173
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• 2003

This study was performed to investigate the kinematic and kinetic differences between functional walking shoe(FWS) and general sports shoe(GSS). The subjects for this study were 4 male adults who had the walking pattern of rearfoot strike with normal feet. The movement of one lower leg was measured using force platform and 3 video cameras while the subjects walked at the velocity of 2/1.5 m/s. The findings of this study were as follows 1. The angle of lower leg-ground and angle of knee with FWS was greater than with GSS at the moment of strike the floor and the moment of second peak ground reaction force. The decreasing rate of angle of ankle was smaller in FWS from the strike phase to the second peak ground reaction force. These mean upright walking and round walking along the shoe surface. 2. The maximal Increased angle of Achilles tendon and the minimal decreased angle of rearfoot were smaller in FWS very significantly(p<0.001). Thus FWS prevent the excessive pronation of ankle and have good of rear-foot control. 3. The vortical ground reaction force and the rate of it to the BW were smaller in FWS statistically(p<0.001). The loading rate was smaller in FWS, too, and thess represent the reduction of load on ankle joint and prevention of injuries on it.

• Korean Journal of Applied Biomechanics
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• v.23 no.3
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• pp.225-233
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• 2013

The purpose of this study was to estimate the potential injury via analyzing ground reaction force components that were resulted from a prolonged-run-induced fatigue. For the present study, passive and active components of the vertical ground reaction force were determined from time and frequency domain. Shear components of GRF also were calculated from time and frequency domain. Twenty subjects with rear foot contact aged 20 to 30, no experience in injuries of the extremities, were requested to run on the instrumented tread-mill for 160 minutes at their preference running speed. GRF signals for 10 strides were collected at 5, 35, 65, 95, 125, and 155 minute during running. In conclusions, there were no significant difference in the magnitude of passive force, impact load rate, frequency of the passive and active components in vertical GRF between running times except the magnitude of active force (p<.05). The magnitude of active force was significantly decreased after 125 minute run. The magnitude of maximum peak and maximum frequency of the mediolateral GRF at heel strike and toe-off have not been changed with increasing running time. The time up to the maximum peak of the anteroposterior at heel-strike moment tend to decrease (p<.05), but the maximum peak and frequency of that at heel and toe-off moment didn't depend significantly on running time.

• Korean Journal of Applied Biomechanics
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• v.28 no.2
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• pp.93-100
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• 2018

Objective: The purpose of this study is to analyze the kinematic characteristics of the national speed skaters in the curve phase of 500-m race. Method: Seven national skaters participated in the study. Race images were acquired using a high - speed camera, and the three-dimensional motion was analyzed. Results: For skaters, whose average velocity in the curve phase is high, the velocity of entry into the straight phase was also fast. The fast skaters showed a larger maximum angle of extension of the knee joints than the relatively slow skaters, and the trunk ROM was smaller. Fast skaters tended to match the timing of the movement of the lower limb with the pelvis, while slow skaters tended to rotate the left pelvis backward. The velocity of the curve phase did not show a clear relationship with stroke time, average trunk angle, and lap time. Conclusion: It is important to skate close to the inner line, keep the trunk ROM below 10 degrees, extend the knee angle to over 160 degrees, and match the movement of the pelvis and lower limb to accelerate in the curve phase. The average velocity of the curves was fast for many athletes, but the competition rankings were low. Therefore, it is possible to improve the performance by optimizing the start technique, the running characteristics of the straight phase, and the physical factors.

• Korean Journal of Applied Biomechanics
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• v.31 no.4
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• pp.234-240
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• 2021

Objective: The purpose of this study is to analyze the distance, number, duration, velocity of sprints generated during women's hockey competition by position to identify sprint patterns. Method: The data was collected in 17 matches between 2016 and 2018, 49 elite women's hockey players were tested using SPI-HPU to identify differences by position using SPSS 25.0. A total of 376 Sprint information was utilized. Results: First, women's hockey players all showed significant differences in the number of sprints, duration, distance, and max velocity depending on their positions. Second, there was a significant difference in the number of sprints in the difference between quarters. And the factors of duration, distance, and max velocity showed differences between positions. Third, according to the results, there were differences in the number of times, duration, distance, and max velocity in the difference between positions. Conclusion: These results can be confirmed the sprint patterns of depends on position during the women's hockey game and can be used as information for the development of physical and tactical training programs.

• Korean Journal of Applied Biomechanics
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• v.29 no.2
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• pp.97-104
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• 2019

Objective: The aim of this study was to investigate the strategies for avoiding moving and stationary walker using body segments during walking. Method: Ten healthy young adults (10 males, age: $24.40{\pm}0.49yrs$, height: $175.80{\pm}5.22cm$, body mass: $70.30{\pm}5.22kg$) participated in this study. Each participant was asked to perform a task to avoid collisions with another walker who was moving or stationary during walking on the 10 m walkway. Both walkers were performed at natural self-selected walking speed. Results: Medio-lateral avoidance displacement of the trunk and the pelvis were significantly increased when avoiding a stationary walker (p<.05). There were no significant differences in medio-lateral center of mass trajectory. Rotation angle of trunk, pelvis and foot on the vertical axis were significantly increased when avoiding a stationary walker (p<.05). Conclusion: Based on our results, when another walker moves continuously, the walker recognizes another walker as the object of social interaction and performs the avoidance strategies while expecting the cooperative distance. On the other hand, when another walker is stopped, it is determined that the walker has an obligation to avoid, and the walker performs a relatively safer avoidance strategy.

• Korean Journal of Applied Biomechanics
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• v.31 no.1
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• pp.59-63
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• 2021

Objective: Through comparative analysis of muscle activity for whole-body vibration, walking and running movements, it is to verify the training effect of whole-body vibration exercise in terms of amount of exercise and muscle activity characteristics. Method: Flat ground walking and slope walking (10 degrees) at a speed of 5 km/h, flat ground running and slope running (10 degrees) at a speed of 11 km/h for running were performed on treadmill, and squats were maintained at 12 Hz, 20 Hz, and 29 Hz conditions on Whole body vibration exercise equipment (Galileo). Muscle activity was analyzed through EMG analysis device for one minute for each condition. Results: The Anterior Tibialis and Erector Spinae show greater exercise effect in whole-body vibration than walking and running. The Rectus Femoris, Biceps Femoris, and Gluteus Maximus have the best effect of exercise in flat running. Whole-body vibration exercise showed greater muscle activation effect as the frequency increased, and exercise effect similar to walking during the same exercise time. Conclusion: The amount of exercise through Whole-body vibration exercise was similar to that of walking exercise, and the Anterior Tibialis and Erector Spinae shows better exercise effect than walking and running.

• Korean Journal of Applied Biomechanics
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• v.32 no.2
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• pp.37-42
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• 2022

Objective: The aim of this study is to analyze the effect of the strength of the ankle support on the walking characteristics and ankle joints when men with flexible flat feet walk. Method: 13 adult male subjects (age: 23.9 ± 2.4 yrs, height: 173.0 ± 5.0 cm, weight: 76.9 ± 13.2 kg, Navicular Drop Test (NDT): 10.2 ± 0.8 mm) participated in this study. Each participant had to walk with the 3 conditions, barefoot, soft arch support and hard arch support, along a walkway while their kinematics was recorded at 100 Hz. Results: Based on the results of this study, it is considered that men with flexible flat feet should use hard arch support rather than bare feet to induce normal arch shape, relieve foot damage caused by excessive ankle joint abnormalities and improve stability. Conclusion: Our results for men with flat flexibility, there was a significant difference in the value of step length when walking was performed using two arch supports with different strengths. The angle of ankle dorsiflexion was significantly increased, and the ankle eversion angle was significantly decreased.