• Korean Journal of Applied Biomechanics
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• v.27 no.3
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• pp.189-195
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• 2017

Objective: The aim of this study was to examine the effect of foot landing type (forefoot vs. rearfoot landing) on kinematics, kinetics, and energy absorption of hip, knee, and ankle joints. Method: Twenty-five healthy men performed single-leg landings with two different foot landing types: forefoot and rearfoot landing. A motion-capture system equipped with eight infrared cameras and a synchronized force plate embedded in the floor was used. Three-dimensional kinematic and kinetic parameters were compared using paired two-tailed Student's t-tests at a significance level of .05. Results: On initial contact, a greater knee flexion angle was shown during rearfoot landing (p < .001), but the lower knee flexion angle was found at peak vertical ground reaction force (GRF) (p < .001). On initial contact, ankles showed plantarflexion, inversion, and external rotation during forefoot landing, while dorsiflexion, eversion, and internal rotation were shown during rearfoot landing (p < .001, all). At peak vertical GRF, the knee extension moment and ankle plantarflexion moment were lower in rearfoot landing than in forefoot landing (p = .003 and p < .001, respectively). From initial contact to peak vertical GRF, the negative work of the hip, knee, and ankle joint was significantly reduced during rearfoot landing (p < .001, all). The contribution to the total work of the ankle joint was the greatest during forefoot landing, whereas the contribution to the total work of the hip joint was the greatest during rearfoot landing. Conclusion: These results suggest that the energy absorption strategy was changed during rearfoot landing compared with forefoot landing according to lower-extremity joint kinematics and kinetics.

• Korean Journal of Applied Biomechanics
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• v.23 no.3
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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.

• Korean Journal of Applied Biomechanics
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• v.17 no.3
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• pp.181-188
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• 2007

The purpose of this study was to investigate the biomechanical effects of wearing different type of insole shoes on gait characteristics in patients with knee osteoarthritis. Seven patients with knee osteoarthritis (Grade 3 & 4 by Kellgren & Lawrence) were participated in the study. They wore two different type of shoes (with Gel-type Insole: GIS, with Normal insole: NIS) during gait. Three dimensional cinematography and Ground Reaction Force(GRF) data were used to get the maximal value of horizontal distance between the center of pressure in GRF and knee joint center, GRF in mediolateral direction, peak value of GRF in frontal plane, vertical compressive force and adduction moment in knee joint. The results were as follows: The maximal value of horizontal distance between the center of pressure in GRF and knee joint center was smaller in GIS than NIS. The peak value of GRF in mediolateral direction was found in 30% of gait cycle, five subjects wearing GIS showed lower value of peak GRF in mediolateral direction than wearing NIS. The peak value of GRF in frontal plane and vertical compressive force in knee joint did not show any difference between GIS and NIS. The adduction moment in GIS decreased in the late stance of gait and the mean value of the adduction moment in GIS smaller than that in NIS. GIS may help to move quickly knee joint center to the center of pressure in GRF, therefore it may prevent increasing the adduction moment in knee joint.

• Korean Journal of Applied Biomechanics
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• v.21 no.3
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• pp.327-334
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• 2011

The objective of this study was to develop a scientific approach for investigating Korean dance in detail, and to examine the intense expressions and various movements, which are based on Danjeon breathing. For the purpose, we analyzed the movement changes and distribution of forces resulting from the switch in movement between exhalation and inhalation while bending, which is the most basic movement in Korean dance. The following conclusions were drawn from this study. In Korean dance, bending with breathing involves less back-and-forth-movement and more up-and-down movement, as compared to bending without breathing; this indicates greater body stability and a wider range of movements while bending with breathing. In addition, less time is required for bending with breathing at the point of switching from exhalation to inhalation, and it involves less movement of the supporting leg; thus, vending with breathing involves faster switching from bending movements to extending movements. While bending, the raised leg goes through a less smooth curve while breathing, which indicates stronger movement of the toes. Bending with breathing requires a greater braking force than bending without breathing, and the vertical force, generated by switching from exhalation to inhalation, is transferred to extending movements using the ground load. The results of this study can be potentially employed to investigate the expressions used in Korean dance on th basis of its principle of forces. Korean dance has evolved into various creative forms, and basic analytical studies of these diverse forms and related breathing methods re required in the future.

• International journal of advanced smart convergence
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• v.9 no.2
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• pp.38-48
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• 2020

The shaking-off the dust from balustrade of higher stories may cause the higher risk of falling accident rate. Main purpose of this study was to quantify an effect of balustrade heights and blanket types on possibility of falling accident relative to one's motor controllability during shaking-off the dust of the blanket from balcony. Female participants, who consisted of total 10 under condition of balustrade height of 3 kinds (90 cm, 110 cm, 130 cm) and blanket types (0.4 kg, 1.6 kg, 3 kg, 200^⁎230 cm), performed repetitively the task of shaking-off the dust of the blanket. Vertical position and velocity of center of mass due to increase of blanket weigh in case of balustrade height of 90 cm was increased, but vertical ground reaction force was decreased swiftly. That is, the higher balustrade height was, the less distance difference between center of mass and center of pressure was.

• Korean Journal of Applied Biomechanics
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• v.20 no.4
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• pp.407-414
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• 2010

The purpose of this study was to evaluate the effect of taping-tape with or without using spiral taping on vertical jump. The subjects for this study were about 20 years old healthy male college students without muscloskeletal diseases. Data for EMG activity and Ground Reaction Force(GRF) were estimated at three knee angles(i.e., 45, 90 & full degree). As a result, there was no statistical significance in max GRF at 90 and full degree regardless of spiral taping-tape. On the other hand, statistical significance was found when vertically jumping at 45 degree knee angle(p<.05). All the data for EMG activity at the three knee angles were not statistically significant, but there was a trend for a decrease in average EMG activity in elector spinae & Medial gastrocnemius at 90 degree knee angle. Based on these data, initial flexor action of knee was stabilized with spiral taping-tape when vertically jumping, resulting in improved muscular activity in Medial gastrocnemius. In conclusion, taping technique for jumping ability associated muscles like quadriceps is also required to develop.

• 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)

• Korean Journal of Applied Biomechanics
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• v.29 no.1
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• pp.9-13
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• 2019

Objective: The aim of this study was to compare gait patterns of elementary school male students in higher grades according to their character styles. Method: 4 extroverted character male subjects (height: $141.35{\pm}7.75cm$, weight: $43.65{\pm}5.80kg$) and 4 introverted character male subjects (height: $145.38{\pm}8.94cm$, weight: $42.15{\pm}10.71kg$) participated in this study. Results: As for walk styles of elementary school male students in higher grades according to their character patterns, there was not significant differences in gait cycle, stride width, stride length and walking speed. According to examination of average ratio of maximum vertical ground reaction force according to their characters divided by weight, elementary school male students in higher grades with extroverted character showed 114.69% of weight and students with introverted character showed 122.82% of weight, which exhibited that students with introverted character had larger ratio as much as 8.13% than students with extroverted character. The statistical significance level was 0.000 showing significant difference. Conclusion: Our results indicated that male students in higher grades with introverted character press ground hard and walk with strong steps. On the other hand, male students with extroverted character walk with light steps.

• Journal of Electrical Engineering and Technology
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• v.11 no.3
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• pp.733-740
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• 2016

To achieve bipedal walking in real human environments, a bipedal robot should be capable of modifiable walking both on uneven terrain with different heights and on flat terrain. In this paper, a novel walking pattern generator based on a 3-D linear inverted pendulum model (LIPM) is proposed to achieve this objective. By adopting a zero moment point (ZMP) variation scheme in real time, it is possible to change the center-of-mass (COM) position and the velocity of the 3-D LIPM throughout the single support phase. Consequently, the proposed method offers the ability to generate a modifiable pattern for walking on uneven terrain without the necessity for any extra footsteps to adjust the COM motion. In addition, a control strategy for bipedal walking on uneven terrain with unknown height is developed. The torques and ground reaction force are measured through force-sensing resisters (FSRs) on each foot and the foot of the robot is modeled as three virtual spring-damper models for the disturbance compensation. The methods for generating the foot and vertical COM of 3-D LIPM trajectories are proposed to achieve modifiable bipedal walking on uneven terrain without any information regarding the height of the terrain. The effectiveness of the proposed method is confirmed through dynamic simulations.

• Korean Journal of Applied Biomechanics
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• v.28 no.2
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• pp.101-108
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• 2018

Objective: The aim of this study was to investigate gender differences in ground reaction force (GRF) components among different speeds of running. Method: Twenty men ($age=22.4{\pm}1.6years$, $mass=73.4{\pm}8.4kg$, $height=176.2{\pm}5.6cm$) and twenty women ($age=20.7{\pm}1.2years$, $mass=55.0{\pm}8.2kg$, $height=163.9{\pm}5.3cm$) participated in this study. All participants were asked to run on an instrumented dual belt treadmill (Bertec, USA) at 8, 12, and 16 km/h for 3 min, after warming up. GRF data were collected from 30 strides while they were running. Hypotheses were tested using one-way ANOVA, and level of significance was set at p-value <.05. Results: The time to passive peaks was significantly earlier in women than in men at three different running speeds (p<.05). Further, the impact loading rates were significantly greater in women than in men at three different running speeds (p<.05). Moreover, the propulsive peak at 8 km/h, which is the slowest running speed, was significantly greater in women than in men (p<.05), and the vertical impulse at 16 km/h, which is the fastest running speed, was significantly greater in men than in women (p<.05). The absolute anteroposterior impulse at 8 km/h was significantly greater in women than in men (p<.05). In addition, as the running speed increased, impact peak, active peak, impact loading rate, breaking peak, propulsive peak, and anteroposterior impulse were significantly increased, but vertical impulse was significantly decreased (p<.05). Conclusion: The impact loading rate is greater in women than in men regardless of different running speeds. Therefore, female runners might be exposed to the risk of potential injuries related to the bone and ligament. Moreover, increased running speeds could lead to higher possibility of running injuries.