• Korean Journal of Applied Biomechanics
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• v.24 no.3
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• pp.277-285
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• 2014

Nakcyguri is one of the offensive weapons most often used in Taekkyon games, The purpose of this study was to investigate kinetic factors on two types of Nakcyguri, one of which uses hip bending and the other uses little it. 12 taekkyoners (males) who are the students of Y University participated in this study. They have been practicing on Taekkyon for five years or more. Positions of CoM, the elapsed time of each phase, ROM of joint and segment angles, ground reaction forces, joint moments of supporting leg were analyzed for this study. The results were as follows; in Nakcyguri with hip bending than without hip bending, anterior/posterior ROM of pelvis, head and swing foot were larger by flexing-extending more, and both vertical and posterior components of GRF were larger during phase 4. It was considered that hip bending produced posterior momentum as well as vertical momentum of trunk during Nakcyguri. In conclusion hip bending was essential and so useful to the successful attack.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.1066-1069
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• 2002

Dynamic postural control varies with the environmental context, specific task and intentions of the subject. In this paper, dynamic postural control against forward-backward perturbations of a platform was estimated using tri-axial accelerometers and a force plate. Ten young healthy volunteers stood upright in comfortable condition on the perturbation system which was controlled by an AC servo motor. With anterior-posterior perturbations, movements of ankle, knee and hip Joints were obtained by tri-axial accelerometers. and ground reaction forces with corresponding displacements of the center of pressure(CoP) by the force plate. The result showed that the ankle moved first and the trunk forward, which implies that the mechanism of the dynamic postural control in forward-backward perturbations, occurred in the procedure of the ankle, the knee and the hip. Knee flexion and hip extension in the period of acceleration, constant velocity and deceleration phase is very important fur the balance recovery. These responses depends on the magnitude and timing of the perturbation. From the present study the accelerometry-system appears to be a promising tool for understanding kinematic accelerative In response to a transient platform perturbation. A more through understanding of balance recovery mechanism may aid in designing methods for reducing falls and the resulting injuries.

• The Journal of Korean Physical Therapy
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• v.21 no.2
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• pp.87-95
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• 2009

Purpose: This study reports the basic reference data of the specific gait parameters for Korean normal adults. Methods: The basic gait parameters were extracted from 73 Adults (35 men and 38 women), 18 to 33 years of age, using a Vicon MX motion analysis system. The segment kinetics, such as joint moment and power, was analyzed at the hip, knee and ankle. Results: The motion patterns are typically associated with a specific phase of the gait cycle. The temporal-spatial gait parameters of Korean normal adults, such as cadence, walking speed, stride length, single support and double support, were similar to the other western reference data. The kinetic parameters of Korean normal adults, such as joint moments of force, joint mechanical power generation or absorption and ground reaction forces, were also similar to other western reference datasets. Conclusion: This study demonstrates that objective gait analysis can be used to document the gait patterns of normal healthy adults. The techniques of 3-dimensional temporal-spatial gait parameters and kinematic parameters analysis can provide a detailed biomechanical description of a normal and pathological gait.

• Journal of Biomedical Engineering Research
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• v.24 no.5
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• pp.435-442
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• 2003

In this paper, biomechanical aspects of dynamic대학교postural responses against forward perturbations were experimentally determined simultaneous measurements of joint angles, accelerations. EMG activations, center of pressure(CoP) movements and ground reaction forces(GRF), Thirteen young healthy volunteers, stood on a flat platform, were translated into the forward direction by an AC servo-motor at two separate velocities(0.1m and 0.2m/s). In order to recover postural balance against the forward perturbation, joint motions were observed in the sequence of the ankle dorsiflexion, the knee flexion and then the hip flexion during the later acceleration phase. Both acceleration patterns at the heel and the sacrum were shown the forward acceleration pattern during the later acceleration phase and early of constant velocity phase as increasing platform velocity, respectively. Tibialis anterior(TA) for the ankle dorsiflexion and biceps femoris(BF) for the knee flexion. the primary muscle to recover the forward perturbation, was activated during the half of acceleration phase. Ankle strategy was used for slow-velocity perturbation, but mixed strategy of both ankle and hip used for the fast-velocity perturbation. In addition, parameters of perturbation such as timing and magnitude influenced the postural response against the perturbation.

• Korean Journal of Applied Biomechanics
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• v.17 no.1
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• pp.69-79
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• 2007

The purpose of this study was to examine the characteristics of throwing motion in the elementary school students from the developmental point of view. For the purpose of this, total of nine subjects(each of three students in five, third, and first grades) were participated. They were asked to throw the ball as far as they can and the motions were videotaped with the 30frames/sec and 1/500 shutter speed. The successful motions for each subject were selected for three dimensional analysis. The collected data were analyzed using DV express 1.0 and Kwon3D 3.0 softwares. The results obtained from this study were as follows; 1. Total time for the throwing motion of the first grade was longer than that of the fifth and third grades. 2. The resultant displacement and velocity of COM for the fifth and third grades were greater than that of the frist grade. 3. The first grade tended to flex the trunk forward excessively during the throwing motion. 4. The fifth grade tended to place the upper arm close to the sagital plane and move the forearm and hand freely. 5. Looking at the greater variability of the angular velocity of the hand segment, the fifth grade seemed to have faster and more flexible movement of the wrist. 6. There were somewhat differences in the patterns and magnitudes of ground reaction forces among the different grades.

• Proceedings of the KIEE Conference
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• 1995.07b
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• pp.874-876
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• 1995

Force and compliance control has been used in the control of legged walking vehicles to achieve superior terrain adaptability on rough terrains. The compliance control requires distribution of the vehicle load over the supporting legs. However, the constraint equations for ground reaction forces of supporting legs are generally underdetermined, allowing an infinite number of solutions. Thus, it is possible to apply an optimization criteria in solving the force setpoint problem. It has been observed that the previous force setpoint optimization methods sometimes cause a system stability problem and/or the load distribution among supporting legs is not well balanced due to a memory effect on the solution trajectory, This paper presents an iterative force setpoint method to solve this problem using an interpolation technique. By simulation it was shown that an excessive load unbalance among supporting legs and the memory effect in the force trajectory are alleviated much with the proposed method.

• Journal of the Ergonomics Society of Korea
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• v.27 no.3
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• pp.93-101
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• 2008

Wedged soles and rocker soles are widespread shoe designs used to prevent the disorders and reduce the pain of the lower extremity caused by arthritis or diabetic feet. In this study, the effect of a shoe with a laterally wedged sole and a rocker sole simultaneously was analyzed on the kinematics and kinetics of the ankle joint during normal walking. Eight male participants without a history of lower extremity disorders were recruited. Each participant performed twenty walking cycles for each of three walking conditions: bare foot, wearing normal shoes and wearing shoes with laterally wedged rocker soles. The differences between the three walking conditions were statistically investigated including spatio-temporal variables, angular displacements, joint moments and ground reaction forces. The results showed that the laterally wedged rocker sole decreased the sagittal variation of angular displacements as well as the frontal/sagittal average moment on the ankle joints compared to the flat sole. In addition, the rate of angular displacements and loading decreased during the heel contact phase.

• Journal of the Korean Society of Physical Medicine
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• v.13 no.4
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• pp.51-58
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• 2018

PURPOSE: This study was conducted to determine if the Harrison hip score (HHS), a tool for assessing hip joint function, and the Burg balance scale (BBS), a general balance assessment tool, actually reflect the balance ability of total hip arthroplasty (THA) patients 3 months after surgery. In addition, this study investigated the initial weight distribution strategy for bilateral lower extremity after THA surgery to understand the balance of THA patients. METHODS: Fourteen 3-month THA patients performed static dual standing and sit-to-stand (STS) tasks. Ground reaction forces on each leg were collected to calculate the weight distribution symmetricity (SWD), and the HHS, functional HHS (f-HHS), and BBS were evaluated. Correlation analyses between SWD and the HHS (also f-HHS) and BBS were then applied to the THA patients. RESULTS: The correlations between functional evaluation tools (HHS, f-HHS, BBS) and SWD were weak strength for the static balance task, but moderate for the dynamic STS task. Among the evaluation tools used in the present study, f-HHS was most useful for evaluation of dynamic balance ability. CONCLUSION: The results suggest that use of HHS, f-HHS, and BBS as functional evaluation tools does not provide meaningful information regarding balance ability, but that they are useful for evaluating dynamic balance ability of THA patients. The dynamic balance ability at 3 months after THA seems to be under development.

• Korean Journal of Veterinary Service
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• v.46 no.2
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• pp.175-179
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• 2023

This study was conducted to find out the compensation strategy through kinetic gait analysis by comparing dog with congenital luxation of the shoulder joint and normal dog. Ground reaction forces were recorded for all limbs while normal poodle dog and poodle dog with shoulder joint luxation was allowed to walk on an instrumented platform. The dogs were evaluated for maximal vertical force (MVF), body load distribution (BLD), and symmetry index (SI). The MVF was increased in the contralateral forelimb of luxated shoulder joint. The SI was also increased in a dog with dislocated shoulder joints in the forelimbs. For BLD, the maximum load distribution increased centrally, but the total load distribution decreased in the ipsilateral forelimb paw. In contrast, total load distribution was increased in the contralateral forelimb paw. During forelimb lameness, changes in weight-bearing load showed compensatory load redistribution. These biomechanical changes may lead to changes in the musculoskeletal system in a dog with luxated shoulder.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1045-1049
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• 2005

In this paper, the dynamic crawling of a five-bar planar mechanism is investigated. One complete cycle of the crawling selected in this study consists of four different steps, i) sliding at one contact point between the mechanism and the ground, ii) changing its configuration without sliding at two contact points, iii) sliding at the other contact point, and iv) again changing its configuration without sliding at two contact points. In this type of crawling, the crawling mechanism maintains the shape of the parallel structure throughout a complete crawling cycle. The modeling algorithm for serial manipulators proposed by M. Thomas and et al.[1] is employed by introducing imaginary joints and links which represent the contact interfaces between the one end of the mechanism and the ground, while the other end of the mechanism is regarded as an end-effector of the imaginary serial manipulator which treats the reaction force and torque at the contact point as external forces. Then, a complete cycle of dynamic crawling of the mechanism is investigated through various computer simulations. The simulation result show that the stable crawling characteristics of the mechanism could be secured when the proper configurations depending on specified frictional constraints are met.