• Korean Journal of Applied Biomechanics
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• v.26 no.3
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• pp.249-255
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• 2016

Objective: This purpose of this study was to analyze the relationship between dimensionless leg stiffness and kinetic variables during gait performance, and its modulation with body weight. Method: The study sample consisted of 10 young women divided into 2 groups (Control, n=5 and Obese, n=5). Four camcorders (HDR-HC7/HDV 1080i, Sony Corp, Japan) and one force plate (AMTI., USA) were used to analyze the vertical ground reaction force (GRF) variables, center of pressure (COP), low limb joint angle, position of pelvis center and leg lengths during the stance phase of the gait cycle. Results: Our results revealed that the center of mass (COM) displacement velocity along the y-axis was significantly higher in the obese group than that in control subjects. Displacement in the position of the center of the pelvis center (Z-axis) was also significantly higher in the obese group than that in control subjects. In addition, the peak vertical force (PVF) and dimensionless leg stiffness were also significantly higher in the obese group. However, when normalized to the body weight, the PVF did not show a significant between-group difference. When normalized to the leg length, the PVF and stiffness were both lower in the obese group than in control subjects. Conclusion: In the context of performance, we concluded that increased dimensionless leg stiffness during the gait cycle is associated with increased velocity of COM, PVF, and the change in leg lengths (%).

• Korean Journal of Applied Biomechanics
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• v.26 no.3
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• pp.303-308
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• 2016

Objective: This study evaluated the vertical and horizontal forces in the frontal plane acting on a pedal due to the vertical alignment of the lower limbs. Method: Seven male subjects (age: $25.3{\pm} 0.8years$, height: $175.4{\pm}4.7cm$, weight: $74.7{\pm}14.2kg$, foot size: $262.9{\pm}7.6mm$) participated in two 2-minute cycle pedaling tests, with the same load and cadence (60 revolutions per minute) across all subjects. The subject's saddle height was determined by the height when the knee was at $25^{\circ}$ flexion when the pedal crank was at the 6 o'clock position (knee angle method). The horizontal force acting on the pedal, vertical force acting on the pedal in the frontal plane, ratio of the two forces, and knee range of motion in the frontal plane were calculated for four pedaling phases (phase 1: $330{\sim}30^{\circ}$, phase 2: $30{\sim}150^{\circ}$, phase 3: $150{\sim}210^{\circ}$, phase 4: $210{\sim}330^{\circ}$) and the complete pedaling cycle. Results: The range of motion of the knee in the frontal plane was decreased, and the ratio of vertical force to horizontal force and overall pedal force in the complete cycle were increased after vertical alignment. Conclusion: The ratio of vertical force to horizontal force in the frontal plane may be used as an injury prevention index of the lower limb.

• Fashion & Textile Research Journal
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• v.14 no.1
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• pp.109-121
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• 2012

This study aims at developing ergonomics patterns for the sleeve of structural firefighting protective clothing through 3D motion analysis in order to ensure efficiency and safety of firefighters who are exposed to harmful environment at work. A new research pattern was developed by applying the total results of 3D motion analysis, changes of body surface length measurements, and 2D data on 3D body shape analysis on the size 3 patterns of the existing coat sleeve. For the sleeves, we used the body surface length of the range of shoulder's flexion and the joint angle of the range of wrist's ulnar deviation. And for the production of structural firefighting protective clothing using the research pattern, we recruited a recognized producer of structural firefighting protective clothing designated by KFI. Unlike everyday clothes, structural firefighting protective clothing should be able to fully protect the wearers from the harmful environment that threatens their lives and should not cause any restrictions on their movement. Therefore, the focus of research and development of such protective clothing should be placed on consistent development of new technologies and production methods that will provide protection and comfort for the wearer rather than production cost reduction or operational efficiency. This study is meaningful as it applied 3D motion analysis instead of the existing methods to develop the patterns. In particular, since 3D motion analysis enables the measurement of the range of motion, there should be continuous research on the development of ergonomics patterns that consider workers' range of motion.

• Journal of the Korean Society of Physical Medicine
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• v.10 no.3
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• pp.95-100
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• 2015

PURPOSE: The purpose of this study is to investigate the effects of the angles of the knee and heel-off on the muscle activity during a bridge exercise. METHODS: 15 healthy adult men and women with the balance ability and joint working range required for performing a bridge exercise participated in this study, in which $120^{\circ}$, $90^{\circ}$ and $60^{\circ}$ angles of the knee-flexion and heel-off were applied during the bridge exercise. RESULTS: Our data showed that there were significant differences in muscle activities of elector spinae and rectus abdominis when $120^{\circ}$ and $60^{\circ}$ angles of the knee were applied, of internal oblique when $120^{\circ}$ and $60^{\circ}$ were applied, and external oblique when $90^{\circ}$ and $60^{\circ}$ were applied. When heel-off was applied, there were significant differences in muscle activities of elector spinae and rectus abdominis when $120^{\circ}$ and $60^{\circ}$ were applied, of internal oblique when $120^{\circ}$ and $60^{\circ}$ were applied, and external oblique when $90^{\circ}$ and $60^{\circ}$ were applied. CONCLUSION: In this study on an application of heel-off to the bridge exercise, we showed that the effect of the angles of the knee on the muscle activities of elector spinae, rectus abdominis, internal oblique and external oblique were all similar to the regular bridge exercise, but overall muscle activities were increased with heel-off when compared with the regular bridge exercise.

• The Journal of Korean Physical Therapy
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• v.30 no.2
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• pp.73-77
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• 2018

Purpose: The prefrontal lobe, supplementary motor area, cerebellum, and basal ganglia are activated during gait. In addition, gait is controlled by nerves, such as the corticospinal tract (CST) and corticoreticular pathway (CRP). In this study, the presence of an injury to the CST and CRP was identified by diffusion tensor imaging and the characteristics of the gait pattern were investigated according to inferior cerebral artery infarction. Methods: One patient and six control subjects of a similar age participated. A 69-year-old female patient had an injury to the left basal ganglia, insular gyrus, corona radiata, dorsolateral prefrontal cortex, and postcentral gyrus due to an inferior cerebral artery infarction. Diffusion tensor imaging (DTI) data was acquired 4 weeks after the stroke. The kinematic and spatio-temporal parameters of gait were collected using a three-dimensional gait analysis system. Results: On 4 weeks DTI, the CST and CRP in the affected hemisphere did not show injury to the affected and unaffected hemisphere. Gait analysis showed that the cadence of spatio-temporal parameter was decreased significantly in the patient. The angle of the knee joint was decreased significantly in the affected and unaffected sides compared to the control group. Conclusion: The results of diffusion tensor imaging showed that although the patient was evaluated to be capable of an independent gait, the quality and quantity of gait might be reduced. This study could help better understand the gait ability analysis of stroke patients and the abnormal gait pattern of patients with a brain injury.

• Korean Journal of Applied Biomechanics
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• v.19 no.4
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• pp.749-759
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• 2009

The purpose of this study was to provide basic information for improving a soft tennis forehand middle volley technique based on kinematic and kinetic analyses of volleys performed by four male national tennis players($33.3{\pm}2.16$ years). The results are as follows. The first phase of the stroke was the longest, covering 64.7% of the stroke time. The displacement of the center of gravity was 48.1% to the right and 54% to the front in the first phase. When impacted, the elbow joint showed the highest average velocity, 3.67m/s, and the upper arm segment displayed the highest angular velocity, $201^{\circ}/s$. The average of the elbow angle and the ball velocity were $149^{\circ}$ and 18.9m/s, respectively. In the ground reaction force, the left and right foot forces in both the x and y directions showed a statistically significant difference. This result seems to indicate that when the left foot is pushed to the right, the force of the right foot is proportional and symmetrical to the left, serving as a supporter.

• Imaging Science in Dentistry
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• v.38 no.1
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• pp.23-27
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• 2008

Purpose: The aim of this study was to evaluate the change in the position of the mandibular condyle within articular fossa by a CBCT after wearing complete denture (CD). Materials and Methods: CBCT of 34 temporomandibular joints were taken from 9 male and 8 female patients with CB $Mercuray^{TM}$ (Hitachi, Japan) before and after wearing a CD for rehabilitation. Position of mandibular condyle within articular fossa at centric occlusion was evaluated with $Vimplant2.0^{TM}$ (CyberMed, Korea) on the central parasagittal view and curved panoramic coronal view of the condylar head. A statistical evaluation was done with SPSS. Results: The range of anteroposterior positional rate (AP) of condylar head within articular fossa was -16-5 and -10-12 respectively on the right and left sides. Before wearing CD, the AP rate showed discrepancy between right and left sides (p<0.05). After wearing CD, both condyles showed a tendency to decrease in posterior condylar position (right side; p<0.05). The average discrepancy between right and left side in mediolateral positional rate (MD) was 15.5 and 4.5 respectively before and after wearing CD. The improvement was observed in mediolateral relationship of both condylar heads after wearing CD (p< 0.01). Before wearing CD, the average horizontal angle of long axis of condylar head was $79.6{\pm}2.7^{\circ}\;and\;80.1{\pm}5.7^{\circ}$ respectively on the right and left sides. After wearing CD, both condyles were rotated in the same direction in average on axial plane. Conclusion: We observed with CBCT the significant clinical evidence in case of positional change of mandibular condyle after wearing complete denture.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.21 no.1
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• pp.5-11
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• 2015

Background: The purpose of this study was to investigate the effects of Mulligan's straight leg raise with traction technique and hold-relax technique on flexibility of hamstring in people with shortened hamstring. Methods: Thirty two subjects participated in this study. The subjects were assigned to either the Mulligan's straight leg raise with traction technique group (n=16) or the hold-relax technique group (n=16). 90-90 straight leg raise test was performed for evaluation of hamstring shortening at initial time of study. After intervention, immediate effect (immediately after intervention) and lasted effect (60 min after intervention) were assessed. Results: In the both Mulligan's straight leg raise with traction technique and hold-relax technique groups, significant improvements on flexibility of hamstring was observed in immediately and 60 minute after intervention (p<.05). However, there are no significant difference was observed between groups (p>.05). Conclusion: In the results of this study, both Mulligan's straight leg raise with traction technique and hold-relax technique show immediately and 60 minute after evaluation effectiveness in flexibility of hamstring of people with shortened hamstring. In addition, although the difference is not statistically significant, Mulligan's straight leg raise with traction technique was more increased average extension angle of knee joint at 90-90 straight leg raise test than the hold-relax technique.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.11 no.4
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• pp.331-338
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• 2017

In this study, a portable x-ray generator was manufactured and a real-time image acquisition system was constructed using the image intensifier from the generated generator. We have developed a real - time position error verification system that can verify whether the artificial joint position is different from the initial image from the acquired image. The template image of the region of interest is extracted from the reference image using the pattern matching technique and compared with the image to be compared. As a result, It is shown that real - time position error verification is achieved by displaying the difference angle. This system is portable type, has a self-shielding facility, and the output of the irradiation device can be manufactured in a small size of 1kw and can be used as a portable type. In case of emergency patients in the non-destructive field for industrial use, It has proved effective for use in small areas such as feet.

• The Journal of Korean Physical Therapy
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• v.12 no.1
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• pp.73-78
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• 2000

The Sit-and-Reach Test (SRT) is commonly nea to assess flexibility of the spine and length of the hamstring muscle, The purpose of this study was to describe hamstring muscle length as reflected by use of the SRT, the Hip Joint Angle (HJA) and Sack length(from C7 to S2) in children, to examine the correlation between Back length, SRT and HJA measurements and to examine gender differences. The 162 subjects were participated without known musculoskeletal and neurological impairments of their spine or lower exeremities. In the Long-silting position, the Back length, SRT and HJA measurements were obtained. A mean Back length value of 46.2cm, a mean SRT value of 29.4cm and a mean HJA of 77,0 degrees were obtained including all subjects. There was a strong correlation between the SRT and HJA measurements (r=.66). There were a difference between boys and girls in Back(p=.0019) and HJA measurements (p=.015). The results of this study suggest that measurements for the SRT and HJA were correlated than Back. The HJA measurements guide treatment more effectively than do Back length and SRT measurements.