• Journal of rehabilitation welfare engineering & assistive technology
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• v.12 no.1
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• pp.1-9
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• 2018

This study is intended to identify how horseback riding affect the bone density of the elderly. A total of 31 normal senior citizens participated in the research, who were randomly divided into two groups: 15 in horseback riding exercise group and 16 in horseback riding machine exercise group. A horseback riding exercise program was carried out for 25 minutes twice a week for 12 weeks. A pre-test was conducted before starting the program and two post-tests were conducted 6 weeks and 12 weeks after exercises in the same way as the pre-test. Measured items were bone density of lumbar vertebrae and femur. In order to identify the changes in measurement variables before exercises and 6 weeks and 12 weeks after exercises, two-way repeated analysis of variance were used. The comparison of changes in the bone density in both groups revealed that there were significant differences in lumbar vertebrae L3, L4, femur trochanter in both groups over time. This study suggests that three-dimensional movements of horses through horseback riding exercises induce normal movements of senior citizens, providing positive effects on their bone density. If appropriate horse riding exercise programs are used considering the health status, time and economic conditions, and preferences of senior citizens, it would improve their quality of life.

• Journal of computational fluids engineering
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• v.21 no.3
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• pp.71-76
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• 2016

In speed skiing, aerodynamic forces play an important role in determining performance of the skier. To predict aerodynamic effects of the posture of the skier on alpine downhill skiing, we constructed equation of motion of the skier and performed the corresponding CFD simulations. Comparing drag and lift of three different skier postures, it has been shown that drag decreases significantly by tucking upper body to lower body and stretching arms forward. Also, aerodynamic lift which worked as downforce in standing posture worked upward in tuck posture, reducing friction force between snow and ski. This indicates that tuck posture have advantages over standing posture in dual mechanism, namely by reducing drag and also increasing lift. By this two-dimensional initial study we could reveal the general tendency of the aerodynamic force over the skier's body. This study not only provides a theoretical foundation for the athletes to understand the aerodynamic effects of skier postures but also shed a light on towards more accurate and rational three-dimensional CFD simulation of skiers in the near future study.

• Journal of the Korean Academy of Clinical Electrophysiology
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• v.10 no.1
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• pp.45-52
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• 2012

Purpose : This study is carried out to investigate the effect of asymmetric exercises on soccer players' vertebral abnormality and weight bearing. Methods : A total of 40 soccer players were divided into either a group of 20 players who use a unilateral foot or a group of 20 players who use both feet. 3-dimensional spine structure analyzer was used to analyze body inclination, pelvic inclination, pelvic torsion, turning of spinal segment, spinal curvature, thoracic kyphosis curvature, lumbar lordosis curvature, left/right weight distribution, and front/back weight distribution. Results : The result of the two groups showed that there were significant differences (p<0.05) for every item except turning of spinal segment and lumbar lordosis curvature. Conclusion : From this result, we can find that spinal and pelvic deformity and body weight are unilaterally supported for soccer players with asymmetric exercises.

• Physical Therapy Korea
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• v.16 no.3
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• pp.9-15
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• 2009

The purpose of this study was to examine contraction of abdominal muscles on surface electromyographic (EMG) activity of superficial cervical flexors, rib cage elevation and angle of craniocervical flexion during deep cervical flexion exercise in supine position. Fifteen healthy subjects were participated for this study. All subjects performed deer cervical flexion exercise with two methods. The positions of two methods were no volitional contraction of abdominal muscles in hook-lying position with 45 degree hip flexion (method 1) and 90 degrees hip and knee flexion with feet off floor for inducing abdominal muscle contraction (method 2). Surface EMG activities were recorded from five muscles (sternocleidmastoid, anterior scaleneus, recuts abdominis, external oblique, internal oblique). And distance of rib cage elevation and angle of craniocervical flexion were measured using a three dimensional motion analysis system. The EMG activity of each muscle was normalized to the value of reference voluntary contraction (%RVC). The EMG activities, distance of rib cage elevation. and angle of craniocervical were compared using a paired t-test between two methods. The results showed that the EMG activities of sternocleidmastoid and anterior scaleneus during deep cervical flexion exercise in method 2 were significantly decreased compared to method 1 (p<.05). Distance of rib cage elevation and angle of craniocervical flexion were significantly decreased in method 2 (p<.05). The findings of this study indicated that deep cervical flexion exercise with contraction of abdominal muscles could be an effective method to prevent substitute motion for rib cage elevation and contraction of superficial neck flexor muscles.

• Korean Journal of Applied Biomechanics
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• v.27 no.3
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• pp.197-203
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• 2017

Objective: The purpose of this study was to determine how exercise intensity affects muscle activity and kinematic variables during squat. Method: Fifteen trainers with >5 years of experience were recruited. For the electromyography (EMG) measurements, four surface electrodes were attached to both sides of the lower extremity to monitor the rectus femoris (RF) and biceps femoris. Three digital camcorders were used to obtain three-dimensional kinematics of the body. Each subject performed a squat in different conditions (40% one-repetition maximum [40%1RM], 60%1RM, and 80%1RM). For each trial being analyzed, three critical instants and two phases were identified from the video recording. For each dependent variable, one-way analysis of variance with repeated measures was used to determine whether there were significant differences among the three different conditions (p<.05). When a significant difference was found, post hoc analyses were performed using the contrast procedure. Results: The results showed that the average integrated EMG values of the RF were significantly greater in 80%1RM than in 40%1RM during the extension phase. The temporal parameter was significantly longer in 80%1RM than in 40%1RM and 60%1RM during the extension phase. The joint angle of the knee was significantly greater in 80%1RM than in 40%1RM at flexion. The range of motion of the knee was significantly less in 80%1RM than in 40%1RM and 60%1RM during the flexion phase and the extension phase. The angular velocity was significantly less in 80%1RM than in 40%1RM and 60%1RM during the extension phase. Conclusion: Generally, the increase of muscle strength decreases the pace of motion based on the relation between the strength and speed of muscle. In this study, we also found that the increase of exercise intensity may contribute to the increase of the muscle activity of the RF and the running time in the extension phase during squat motion. We observed that increased exercise intensity may hinder the regulation of the range of motion and joint angle. It is suitable to perform consistent movements while controlling the proper range of motion to maximize the benefit of resistance training.

• Korean Journal of Applied Biomechanics
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• v.26 no.4
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• pp.361-367
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• 2016

Objective: The aim of this study was to compare three-dimensional kinematic changes of the lower extremity between the two different braking distances during snowplow in alpine skiing. Method: Six alpine ski instructors (age: $25.3{\pm}1.5yr$, height: $169.3{\pm}2.9cm$, weight: $66.2{\pm}5.9kg$, career: $4.2{\pm}2.9yr$) participated in this study. Each skier was asked to perform snowplow on the two different braking distances (2 and 4 m). Results: Snowplow and edging angles (p = .006 and p = .005), ankle adduction and inversion (p = .033 and p = .002), knee extension (p = .003), and hip abduction and internal rotation (p = .043 and p = .006) were significantly greater in the 2 m than in the 4 m braking distance. Conclusion: Based on our results, we suggest that skiers should make greater snowplow and edging angles on the shorter braking distance. In this situation, ankle joint adduction/inversion angle and hip joint internal-rotation make greater snowplow angle, and hip joint abduction make greater edging angle. In addition, greater knee joint extension angle may lead to more posteriorly positioned center of mass.

• Korean Journal of Applied Biomechanics
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• v.17 no.2
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• pp.157-166
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• 2007

This study was to compare the major kinematic factors between the success and failure group on performing the back somersault motion in floor exercise. Three gymnasts(height : $167.3{\pm}2.88cm$, age : $22.0{\pm}1.0years$, body weight : $64.4{\pm}2.3kg$) were participated in this study. The kinematic data was recorded at 60Hz with four digital video camera. Two successful motions and failure motions for each subject were selected for three dimensional analysis. 1. Success Trail It was appear that success trail was larger than failure group in projection velocity, but success trail was smaller than failure trail in projection angle. Also it was appear that success trail was longer than failure group in the time required. Hand segment velocity and maximum velocity in success trail were larger than those in failure trail, and this result was increasing the projection velocity and finally increasing the vertical height of center of mass. At the take-off(event 2), flection amount of hip and knee joint angle was contributed to the optimal condition for the take-off and at the peak point, hip and knee joint angle was maximum flexed for reducing the moment of inertia. Also in this point, upper extremities of success trail extended more than those of failure trail. in this base, success trail in upward phase(p3) 2. Failure Trail It was appear that failure trail was smaller than success trail in projection velocity, but failure trail was larger than success trail in projection angle. Also it was appear that failure trail was more short than success trail in the time required. Hand segment velocity and maximum velocity in failure trail were smaller than those in success trail, and this result was reducing the projection velocity and finally reducing the vertical high of center of mass. At the take-off(event 2), flection amount of hip and knee joint angle wasn't contributed to the optimal condition for the take-off and at the peak point, hip and knee joint angle wasn't maximum flexed for reducing the moment of inertia. Also in this point, upper extremities of failure trail didn't extended more than those of success trail.

• Fashion & Textile Research Journal
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• v.24 no.6
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• pp.694-706
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• 2022

This study focusses on the development of a motion-sensing smart leggings prototype with the help of a module that monitors motion using a fiber-type stretch sensor. Additionally, it acquires data on Electrocardiogram (ECG), respiration, and body temperature signals, for the development of smart clothing used in online exercise coaching and customized healthcare systems. The research process was conducted in the following order: 1) Fabrication of a fiber-type elastic strain sensor for motion monitoring, 2) Positioning and attaching the sensor, 3) Pattern development and three-dimensional (3D) design, 4) Prototyping 5) Wearability test, and 6) Expert evaluation. The 3D design method was used to develop an aesthetic design, and for sensing accurate signal acquisition functions, wearability tests, and expert evaluation. As a result, first, the selection or manufacturing of an appropriate sensor for the function is of utmost importance. Second, the selection and attachment method of a location that can maximize the function of the sensor without interfering with any activity should be studied. Third, the signal line selection and connection method should be considered, and fourth, the aesthetic design should be reflected along with functional verification. In addition, the selection of an appropriate material is important, and tests for washability and durability must be made. This study presented a manufacturing method to improve the functionality and design of smart clothing, through the process of developing a prototype of motion-sensing smart leggings.

• Korean Journal of Applied Biomechanics
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• v.22 no.2
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• pp.151-158
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• 2012

The purpose of this study was to investigate variables of significantly difference as the structure of the spine, pelvic deviation and foot pressure between undergraduates and golf player subjects. The subjects of study were composed of 20 male golf players and 20 male undergraduates. Both groups were right handed persons. The measurement tools of this study were Formetric 4D(Diers, Germany) which is a three dimensional measure. The result are the follows: there were a significant difference between golf players and general students of trunk imbalance, pelvic tilt, pelvic torsion, pelvic rotation, surface rotation, lumbar lordotic curve, foot pressure(fore & behind foot), weight distribution(right & left foot). In conclusion, golf players might cause transform of spine and foot pressure due to golf exercise for several years. Such as imbalance affect to induce functional impairment and pain of musculoskeletal system, and appropriate evaluation and treatment were necessary for golf players.

• The Journal of Korean Physical Therapy
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• v.15 no.4
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• pp.82-89
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• 2003

Although many current low back pain exercise incorporate proprioceptive training, very little research has been performed on proprioception of the low back. To determine wether reposition error is different in male than female. Eighteen young individuals took part in the research, seven male and eleven female. The 3-dimensional position of the lumbar was measured with a CMS70P. Reposition error was calculated as the absolute difference between the neutral position and return position. No significant differences in reposition error were found between male and female. No significant correlations were identified between reposition error and movement direction.