• The Journal of Korean Physical Therapy
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• v.25 no.5
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• pp.316-321
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• 2013

Purpose: The aimed of this study was to investigate muscle activation related to postural stability according to different frequency of whole body vibration during quiet standing, to identify the most effective training conditions that cause the highest neuromuscular responses, and to evaluate the difference of EMG activation according to the anatomical position of the muscle - proximal or distal from the vibration platform. Methods: Eighteen healthy subjects voluntarily participated in this single-group, repeated-measures study in which EMG data from upper trapezius, rectus abdominalis, external oblique abdominalis, elector spinae, gluteus maximus, rectus femoris, semitendinosus, and gastrocnemius were collected over different frequencies (0-5-10-15-20-25Hz) for each subject during quiet standing. Results: We observed a statistically significant difference in the mean values of %RVC of muscular activation according to different frequencies of whole body vibration during quiet standing in all muscles (p<0.05). Conclusion: Our results indicate that lower frequencies of vibration result in low muscular activation, and higher frequencies elicit high muscular activation. However, the most effective training condition that caused the highest activation was 20 Hz. In addition, the proximally located lower extremity muscles (GCM, RF, ST, GM) showed higher activation than the distally located trunk and neck muscles (ES, EO, RA, UT) together with increasing frequency.

• Korean Journal of Applied Biomechanics
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• v.14 no.2
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• pp.15-26
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• 2004

The purpose of this study was to investigate the kinematic variables of peters motion in parallel bars. The subjects were 3 male national gymnasts. For this study, kinematic data were collected using video camera. Coordinate data were low-pass filtered using a fourth-order Butterworth with cutoff frequency of 6Hz. Each valuables analyzed was used to compare kinematic features between the subjects. The conclusions were as follows; 1. For a stable regrasp motion, the subjects appeared to increase horizontal and vertical displacement during the DS phase because it induce a vertical elastic of body and reaction of bar for the US phase. 2. For a stable hand standing motion of the regrasp, the subjects appeared to maintain the fast vertical and horizontal velocity during the DS phase, but in contrary during the US and Air phase the vertical and horizontal velocity appeared to do decrease. 3. When the arm lean angle and the trunk lean angle maintain a big angle during the DS phase, the subjects appeared to do a stable performance to release in a high position.

• Korean Journal of Applied Biomechanics
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• v.20 no.3
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• pp.311-318
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• 2010

This study examined the double piked dismount among the landing techniques of parallel bars based on three-dimensional motion analysis. Four male national gymnasts were the subjects. This study was performed to provide quantitative data highlighting players strengths and weaknesses to enable more stable landing technique. The variables analyzed were the position and velocity of center of gravity(CG) and angles of shoulder joints, hip joints, and trunk. The results are as follows: S1 secured the height of flight with fast vertical rise. After the easy spin in the air, he conducted a stable landing maintaining a proper hip joints angle. S2, S3, and S4, however, began the backward somersault already before leaving the bars, so they moved backward greatly making it more difficult to achieve a higher flight path. As a result, they couldn't control the velocity of their backward movement at landing. For a stable landing, they have to maintain the negative shoulder angle when rising, minimize both antero-posterioror side-to-side movements by doing a strong tap using hip joints, to secure the height of flight before the somersault. Results also show that at the descent, they should conduct rapid spinning by increasing their shoulder and hip joints to the maximum while controlling their velocity.

• Korean Journal of Applied Biomechanics
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• v.20 no.3
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• pp.261-266
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• 2010

Human body is hard to be in perfect balance during walking. Most of time the trunk is supported by one leg and the center of mass(COM) falls to the contralateral side. Thus, dynamic variables such as the velocity of the COM should be considered when gait stability is evaluated. The purpose of this study was to investigate whether the extrapolated center of mass(XCom) which utilized the COM position and its velocity, is appropriate to evaluate gait stability. Ten healthy adults participated in this study and performed 3 different types of gaits(normal(NG), hands on waists(HWG), and hands on shoulders(HSG)) onto 4 different types of obstacle(obstacle height: 0%, 30%, 40% and 50% of leg length). Medio-lateral Com-CoP and XCom-CoP inclination angle were calculated during support phase. For all condition, greater M-L XCoM-CoP inclination angles were found(p<.05) compared with those of matched obstacle height CoM-CoP. Especially, M-L XCoM-CoP inclination angle at 50% height revealed the best condition for monitoring dynamic stability. Significantly increased in M-L XCoM-CoP inclination angle was found(p<.05) as obstacle height increased on NG and HWG.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.576-583
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• 2000

A robust position control using a sliding mode controller is adopted for the stable dynamic walking of the biped. For the biped robot that is modeled with 14 degrees of freedom rigid bodies using the method of the multibody dynamics, the joint angles for simulation are obtained by the velocity transformation matrix using the given Cartesian foot and trunk trajectories. Hertz force model and Hysteresis damping element which is used in explanation of the energy dissipation during contact with ground are used for modeling of the ground reactions during the simulation. By the obtained that forces which contains highly confused noise elements and the system modeling uncertainties of various kinds such as unmodeled dynamics and parameter inaccuracies, the biped system will be unstable. For that problems, we are adopting a nonlinear robust control using a sliding mode controller. Under the assumption that the esimation error on the unknown parameters is bounded by a given function, that controller provides a successful way to preserve stability and achieve good performance, despite the presence of strong modeling imprecisions or uncertainties.

• Journal of Fashion Business
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• v.18 no.2
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• pp.54-65
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• 2014

This study developed basic pattern for competition figure skating wear for school girls. Figure skating wears are difficult for making basic patterns based on standard size chart, because girls' body size are slimmer and more slender compared to the general girl's and the competition wears such as, swim suit with sleeves are, closely in contact with the player's body. The competition wears for school girl was made with consideration of changing of the body shape, physical exercises, and various specificities according to stretch material. To raise artistic effect while doing beautiful motions, and to assist in facile technique motions, competition wears need to have enough ease on the side line from waist to armpit, from armpit to wrist, and in trunk girth including crotch girth. Also, to stand out in beauty, a costume designing has a proper skirt position, length, flare width, and a tight bodice according to the player's body proportion. Most of the customers are displeased at the high price, unfitness of size, insufficient design, and difficulty in access, since they are not sold in sporting goods store. Therefore, a competition wear's basic pattern was made through scientific and emotional process including concerns on material properties, room for activities, and ideal body proportion. Systemizing the basic patterns of production method will solve high repairing expenses, unsuitable sizing, and improve accessibility for purchase.

• Journal of the Korean Society of Physical Medicine
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• v.15 no.3
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• pp.21-27
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• 2020

PURPOSE: This study investigated the efficacy of interferential current (IFC) treatment on the improvement of pain, disability, and balance in patients with chronic nonspecific low back pain. METHODS: A double-blind randomized clinical trial was conducted with 40 patients with chronic nonspecific low back pain. The patients were randomly allocated into two groups: the IFC treatment group (n = 20) and the placebo treatment group (n = 20). The IFC group received 30 minutes of IFC treatment on the lumbar region, while the placebo group received IFC treatment without real electrical stimulation. The intervention was administered five days a week for two weeks. RESULTS: The primary outcomes of resting pain and pain during functional movement were measured by a visual analogue scale. The secondary measurements included the Oswestry disability index (ODI) for low back pain and postural sway. The measurements were performed before and after the two-week intervention period. Compared to the placebo treatment group, the IFC treatment group showed significantly greater improvement in pain during anterior trunk flexion in the standing position (p = .029), ODI (p = .039), and postural sway when subjects stood with their eyes closed (p = .010) at the end of the intervention. CONCLUSION: Our findings show that IFC treatment can improve pain, disability, and postural sway, thus, highlighting the benefits of somatosensory stimulation from IFC.

• Journal of International Academy of Physical Therapy Research
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• v.7 no.2
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• pp.1051-1055
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• 2016

The purpose of this study was to investigate the effect of the screen size of smart devices on the bending angle of the cervical spine. The subjects of this study were 30 healthy adults(15 men and 15 women) who used smartphones and tablet PC(personal computer). The changes in the bending angle of the upper and lower cervical spine were measured in the subjects after they had used a smartphone and a tablet PC for 300 seconds each. To make sure that all subjects began in the same starting position, an angle-measuring instrument was used to set the angles of the ankle, knee, hip, and arm joints to 90 degree. The subjects were asked to keep the trunk straight. They were asked to hold a smartphone in their hand and to bend their neck so that they could look down at the screen. Once they began using the smartphone in this manner, they were free to change their posture. We used a paired t-test to compare the bending angle of the cervical spine on subjects who used smartphones and tablet PC in the long-term and short-term there production error of cervical and the significance level was cervical. The results showed that, when using a smartphone and a tablet PC for 300 seconds, there was no significant difference in the bending angle of the upper cervical spine(p>.05), although there was a significant difference in the bending angle of the lower cervical spine(p<.05).

• Korean Journal of Applied Biomechanics
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• v.16 no.3
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• pp.65-74
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• 2006

This study was attempted to Kinematical characteristics of the Endo $360^{\circ}$El-grip Swing on the horizontal bar. To do this, we selected and analyzed the performance of two athletes who did Endo $360^{\circ}$El-grip Swing in the horizontal bar competition of male artistic gymnastic in the 22nd Universiad Games 2003 Daegu. We drew the conclusions from the kinematical factors that were came out through analyzing three-dimensional cinematography of the athletes' movements, by using two video cameras. In point of analyzing the actual competition situation, it is expected that gymnastics and coaches have the effective informations, and the following conclusion had resulted. 1. When performing Endo $360^{\circ}$El-Grip, the average for entire required time was $1.93{\pm}0.06sec$. The average for descent phase time was $0.24{\pm}0.02sec$, ascent phase time was 0.22${\pm}0.07sec$, connecting phase time was $0.87{\pm}0.07sec$, and El-Grip phase time was $0.61{\pm}0.02sec$. The descent phase need short period of time but however to have a stable performance, ensuring ascent and connecting phase time are needed. El-Grip phase need short period of time to have a stable re-grasp. 2. To have a convenient preparation for El-Grip in descent and ascent phase, lowering CM, and ease up in sway and plunge from the High Bar would make descent and ascent even more faster and would have increase effect in trunk rotation. 3. In descent and ascent phase, if shoulder angle and arm slope is dwindling then it would effect rotation angle so might risk it from hitting a Bar when putting legs in and out. 4. In connecting phase, it requires some time to show stable performance when El-Grip phase is continued by using hip angle which would make trunk rotation angle bigger and make descent and ascent time slower. 5. In El-Grip phase, when doing motions like hand standing. using hip angle more than maximum would make CM even faster and it is stable position while performing.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.4 no.1
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• pp.53-61
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• 2010

In this paper, We investigated the characteristic analysis of flexibility and muscle strength for exercise to verify capacity in rehabilitation exercise of lumbar using lumbar strengthen exercise instrument. We have experiment in 20th years man and woman who are 20 subject with no medical history, we divided subjects into control group with no exercise and training group with lumbar strengthen exercise. We used Hi-Spine(Medicalscience.korea) also, provided exercise 40 minute a day, three days a week and progressed total four weeks. Moreover in our experiment, subjects exercised four postural position as lay down, sit, stand and stretch each ten minute. We measured trunk extension backward, trunk flexion forward, evaluation of based physical fitness and lumbar joint torque. The reults have shown that there more improved all for flexibility, based physical fitness and lumbar joint torque in training group than control group. We indicated that by rotating 3-D axis movement flatform of exercise instrument, muscle spindle in subject have been stimulated and these rotation direction and angle caused muscle tonus and contraction that makes muscle, flexibility and based physical fitness improve more. Our study can be used rehabilitation exercise program to aged people and patient with lumbar injury.