• International Journal of Control, Automation, and Systems
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• v.4 no.3
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• pp.325-332
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• 2006

The dynamic responses of human standing postural control were investigated when subjects were exposed to long-term horizontal vibration. It was hypothesized that the motion of standing posture complexity mainly occurs in the mid-sagittal plane. The motor-driven support platform was designed as a source of vibration. The AC Servo-controlled motors produced anterior/posterior (AP) motion. The platform acceleration and the trunk angular velocity were used as the input and the output of the system, respectively. A method was proposed to identify the complexity of the standing posture dynamics. That is, during AP platform motion, the subject's knee, hip and neck were tightly constrained by fixing assembly, so the lower extremity, trunk and head of the subject's body were individually immovable. Through this method, it was assumed that the ankle joint rotation mainly contributed to maintaining their body balance. Four subjects took part in this study. During the experiment, the random vibration was generated at a magnitude of $0.44m/s^2$, and the duration of each trial was 40 seconds. Measured data were estimated by the coherence function and the frequency response function for analyzing the dynamic behavior of standing control over a frequency range from 0.2 to 3 Hz. Significant coherence values were found above 0.5 Hz. The estimation of frequency response function revealed the dominant resonance frequencies between 0.60 Hz and 0.68 Hz. On the basis of our results illustrated here, the linear model of standing postural control was further concluded.

• Physical Therapy Korea
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• v.25 no.3
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• pp.12-18
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• 2018

Background: Passive straight leg raising (PSLR) is the common clinical test to measure of hamstring muscle length. Hip flexion angle contributes to change the lumbopelvic rotation during PSLR. Pressure biofeedback unit (PBU) is commonly used to detect lumbopelvic movement during lower limb movements. Thus, there may be the relationship between pressure of PBU and lumbopelvic motion during PSLR. Objects: The objective of this study was to determine the relationship between pressure of PBU and lumbopelvic motion during PSLR. Methods: Thirty two subjects participated in this study. A three-dimensional motion analysis system were used to measure the lumbopelvic angle during PSLR, while recording the pressure of PBU according to angle of PSLR by 10 degree increments. Pearson product moment correlations and linear regression analysis were used to describe the relationship between variables. Results: The results showed that there was a significant relationship between the lumbopelvic and angle of PSLR (Pearson's r=.83, p<.05), between the pressure of PBU and angle of PSLR (Pearson's r=.75, p<.05), and between lumbopelvic motion and pressure of PUB (Pearson's r=.83, p<.05). Linear regression equation using lumbopevic angle as an independent factor was as follows: Pressure of PBU = 47.35 + (2.55 ${\times}$ angle of lumbopelvic motion) ($R^2=.69$, p<.05). Conclusion: Results of the present study indicate that pressure of PBU can be used to indirectly detect the amounts of lumbobevic motion during muscle length test or stretching of hamstring.

• Journal of Fashion Business
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• v.15 no.6
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• pp.148-162
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• 2011

The purpose of this study is to analyze lower body types of women and provide information of body improvement of Korean adult female clothing product to ready-made clothes companies. As for the method of this study, it was conducted to measure the parts of the lower body of adult women at the age from 19 to 24 years, to analyze their characteristics and to categorize body types. For study, it was measured 150 female women in Seoul. Data was analyzed by used SPSS/WIN 19.0 Program. The results of this study are as follows. The means of the subjects in their early 20s are 159.8cm in height, 67.0cm in waist circumference, 91.6cm in hip and 52.0kg in weight. As a result of comparison with the $5^{th}$ Korean's human body size on measurement data, 20 items out of 33 items showed significant difference. Factor analysis was executed for 66 body measure and calculation items to draw the body construction factors of the women's lower body in their early 20s and principal component analysis was performed by orthogonal varimax rotation to clarify the measurement of factors and to derive explanatory factors. As result of Cluster analysis, body types' characteristics divide into 3 types. Type1 has tall and fat body form, type2 has shortest and curvy body form and type3 has average height and the most skinny body form.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.9
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• pp.1033-1039
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• 2012

Artificial joints are used when joints lose their function because of either the destruction or damage of the composing bones of the joints. To evaluate the primary stability of a femur-implant system, the relative displacement caused by a repeated load is measured immediately after the insertion of the artificial joint. For more accurate stability evaluation, the accurate measurement of the penetration displacement of the artificial joint to the bone and the rotation angle of the artificial joint is essential. In this study, to evaluate the primary stability of the femur-implant system, we propose a new relative displacement measurement method. By using this new method, we comparatively evaluate the primary stability for various surgical methods and the varying stiffness of the cadaver femur-implant itself.

• Journal of the Korean Society of Physical Medicine
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• v.16 no.2
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• pp.71-79
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• 2021

PURPOSE: Chronic low back pain is one of the main factors that affect the quality of life and cause problems of gait and balance in elderly people. This study investigated the correlation between the Oswestry disability index (ODI), Berg balance scale (BBS), and kinematic data measured while analyzing the gait of elderly people with chronic back pain. METHODS: A total of 29 subjects participated in this study. The ODI, BBS, and kinematic data of lower extremities were measured while walking. All data were analyzed using Pearson's correlation coefficients and the significance was measured at .05. RESULTS: ODI had a significant correlation with 1, 13, and 14 items of BBS (p < .05), and left hip external rotation and right ankle abduction respectively in the stance and swing phase of gait (p < .01). 13 items of BBS had a significant correlation with the right ankle abduction in the stance phase of gait (p < .01). In addition, 14 items of BBS had a significant correlation with right and left ankle abduction in the stance and swing phase of gait (p < .01). CONCLUSION: While attempting to predict chronic low back pain and balance issues, it may be useful to check the right ankle abduction in the stance and swing phase of gait. In the future, it would be helpful if some simple tests could be designed to assess balance in elderly people with chronic low back pain.

• Journal of the Korea Society of Computer and Information
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• v.24 no.5
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• pp.93-102
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• 2019

The nation's fraternity and elite players who have built up a global bicycle infrastructure often find it to be a problem with the bicycle's speed and speed reduction, pain in knees and hip joints, or even with the bike itself, or with the bike's own physical defects or a riding posture. However, we found that most cases of cleat adjustment errors were likely to be true. Accurate adjustment of the cleats is the most important of the entire fitting process and can be the basis for improving the ability of the bicycle rider and preventing injury. Therefore, the study was intended to give a prior study of bicycle fitting, which can improve bicycle efficiency and prevent injury when riding bicycle, and specific ways of adjusting bicycle shoe cleats, and the following results were obtained. First, the cleat characteristics of Shimano, LOOK and Speedplay, which are currently used in public, and the characteristics during the cleat adjustment process, were derived. In addition, the structure and characteristics of dedicated shoes using cleats and the method of using pedalling by the structure of shoes after adjusting the cleats were derived. Second, the position of the shoe and its relationship with torque in pedalling was discussed, and the method of adjusting front and back of cleats was derived. Third, leg length, ASIS, Q-Angle and Q-factor etc. were analyzed and the method of setting and adjusting cleat left and right values were derived. Fourth, the relationship between walking angle and cleat rotation was analyzed, the method was derived, and the torque size and angle behind the cleat adjustment were compared and analyzed using the spinner to indicate the torque and the effective mean torque angle after the cleat adjustment.

• Journal of the Korea Convergence Society
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• v.12 no.8
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• pp.61-66
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• 2021

The purpose of this study was to investigate the relationship between vertical jump and lower extremity muscle strength of elementary school baseball players. This study subjects were conducted with a total of 40 subjects. Vertical jump was measured using a vertical jump gauge, and a hand held dynamometer was used to measure lower extremity muscle strength. For the measurement of lower extremity muscle strength, flexion·extension·adduction·abduction·internal rotaiton·external rotation of both hip joint, flexion·extension of both knee joint, dorsi flexion·plantar flexion of both ankle joint were measured. pearson's correlation analysis was used to analyze the correlation between vertical jump and lower extremity muscle strength. From these results, it was found that the stronger the leg muscles except for the plantar flexion, the higher the vertical jump was, indicating a positive correlation. In future studies, follow-up studies on the relationship between batting ability and vertical jump & lower extremity muscle strength are needed.

• Journal of The Korean Society of Integrative Medicine
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• v.11 no.2
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• pp.207-219
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• 2023

Purpose : This study was conducted to investigate the changes in trunk movement and ground reaction during sit to stand motion using visual feedback. Methods : Fifteen adults (average age: 23.53±1.77 years) participated in this study. An infrared reflective marker was attached to the body each participant for motion analysis, and the participants performed sit to stand motion while wearing a hat attached with a laser pointer, which provided visual feedback. First, the sit to stand action was repeated thrice without obtaining any visual feedback, followed by a three minute break. Next, the laser pointers attached to hats were irradiated on a whiteboard, located at a distance of 5 m in front of the chairs, on which the participants sat; a baseline was set, and the participants performed stand up movements three times under this condition. A visual feedback was provided to the participants to prevent the laser pointers from crossing the set baseline. During each stand-up movement, the position of the reflective marker attached to the subject's body was recorded in real time using an infrared camera for motion analysis. The trunk movement and ground reaction force were extracted through recorded data and analyzed according to the presence or absence of visual feedback. Results : The results indicated that in the presence of a visual feedback during the sit-to-stand movements, the range of motion of the trunk and hip joints decreased, whereas that of the knee and ankle joints increased in the sagittal plane. The rotation angle of the trunk in the horizontal plane decreased. The left and right movement speed of the center of pressure increased, the pressing force decreased, and the forward and backward movement speed of the trunk decreased. Conclusion : The results suggest that the efficiency and stability of the stand up movement of a body increase when a visual feedback is provided.

• Korean Journal of Applied Biomechanics
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• v.12 no.2
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• pp.259-278
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• 2002

This study divided straight success, pade success and failure with 7male golfers who have experiences more than 3 years, analyzed kinematic factors of golf swing to suggest scientifically. The conclusions were follows. 1) The wrist angle has significant difference in straight success, pade success and failure when swing of every pattern. There is no significant difference in pade success and failure. 2) The body twist angle has no significant difference in straight success, pade success and failure when swing of every pattern. There is no significant difference in pade success and failure. 3) The shoulder joint rotation angle has no significant difference in success, pade success and failure when swing of every pattern. There is no significant difference in pade success and failure. 4) The left hip joint vertical angle has no significant difference in straight success, pade success and failure when swing of every pattern. There is no significant difference in pade success and failure. 5) The hip joint rotation angle has no significant difference in straight success, pade success and failure when swing of every pattern. There is no significant difference in pade success and failure. 6) The trunk angle has no significant difference in straight success, pade success and failure when swing of every pattern. There is no significant difference in pade success and failure. 7 )The left knee joint angle has no significant difference in straight success, pade success and failure when swing of every pattern. There is no significant difference in pade success and failure. This study divided golf swing motion of pattern change in straight success, pade success and failure and analyzed the kinematic factors by 3-dimension cinematography to improve performance. In the future, many researchers have to study kinematic analysis to improve performance in every events.

• Korean Journal of Applied Biomechanics
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• v.12 no.2
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• pp.159-177
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• 2002

The purpose of this study was to investigate the relations between the segments of the body, the three dimensional anatomical angle and the angular velocity of the air born phase and understand the control mechanism of the high-bar movement, the somersault, the double somersault, the double somersault with full twist. For this study seven well trained university gymnastic volunteered, Zatsiorky and Seluyanov(1983, 1985)'s sixteen segment system anatomical model was used for this study. For the movement analysis three dimensional cinematographical method(Arial Performance Analysis System : APAS) was used and for the calculation of the kinematic variables a self developed program was used with the LabVIEW 5.1 graphical profromming(Johnson, 1999) program. By using Eular's equations the three dimensional anatomical Cardan angles of the joint and angular velocity were defined. As a result of this study 1. As the rotation of the body increased in the air born phase the projection angle of the CM of the total increased, this resulted the increased of the max hight of the CM. 2. In three dimensional angular velocity the Z axis(vertical direction) projection angular velocity increased as the rotation of the body increased in the airborn phase, but the Y axis and the X axis projection angular velocity did not show significant differences. 3. As the rotation of the body increased in the air born phase the angular movement of the shoulder and the hip showed significant change. These movement act as the starter in the preparation phase. 4. The somersault angle, the twist angle, the tilt angle of the upper body related to the global reference frame in the releas phase the average somersault angle of the three types of high-bar movement was $57.7^{\circ}$, $38.8^{\circ}$, $39.7^{\circ}$, the average tilt angle was $-1.5^{\circ}$, $-5.4^{\circ}$, $-8.4^{\circ}$, the average twist angle was $13.4^{\circ}$, $10.6^{\circ}$, $23.3^{\circ}$. This result showed that the somersault with full twist had the largest movement.