• The Journal of Korean Physical Therapy
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• v.22 no.5
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• pp.57-61
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• 2010

Purpose: The purpose of this study was to identify the effect of active foot arch support on the muscles of lower extremity electromyographic activity during squat exercise in persons with pronated foot. Methods: The study subjects were 16 persons with pronated foot. They have no history of surgery in lower extremity and trunk and limitation of range of motion or pain when performing squat exercise. Each subject was measured the navicular drop (ND) to determine the pronated foot. And then the subjects were asked to perform three repetitions of a $90^{\circ}$ knee flexion squat in both conditions which are 1) preferred squat and 2) squat with active foot arch support. Results: Paired t-test revealed that squat with active foot arch support produced significantly greater EMG activities in abductor hallucis (p=0.00), proneus longus (p=0.03) and gluteus medius (p=0.04) than preferred squat. But the EMG activities of tibialis anterior, vastus medialis oblique and vastus lateralis were not showed significantly different between the both squat conditions. Conclusion: The findings of this study suggest that active foot arch support during squat increase the activities of lower extremity muscles which are the abductor hallucis, proneus longus and gluteus medius. Also, the abductor hallucis which is one of the planter intrinsic muscle and peroneus longus play a role in support of the foot arch and active foot arch support induced the increase of the activity of gluteus medius. Therefore active foot arch support can change the lower extremity biomechanics as well as passive foot support such as foot orthotics and taping.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.10a
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• pp.24-24
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• 2003

For the elderly, achieving a close-to-normal ambulation is important for activities of daily life. Recent researches of SE(Silver Engineering) restoring physical ability would help the elderly by developing the advanced gait assisting devices and orthoses. For the applications using the advanced technologies, the gait characteristics of the elderly must be understood. However, a few studies were performed to investigate the physiological or pathological gaits. The purpose of this study is to provide the gait analysis data and also to investigate relationships between alignment of the lower limb, foot progression angle and knee joint moments in the healthy elderly. By participating a total of 20 healthy elderly persons in this study, the following facts were found: 1) Cadence showed 114.8 steps/min, gait speed showed 1.05 m/s, time per a stride showed 1.06 sec, time per a step showed 0.53 sec, single-supporting phase was 0.41 sec, double-supporting phase was 0.24 sec, stride length was 1.04m, Step length was 0.56m; 2) The maximum knee flexion angle through swing phase showed left 46.82$^{\circ}$, right 40.19$^{\circ}$ and the maximum knee extension angle showed left -1.32$^{\circ}$, right 2.01$^{\circ}$. Knee varus showed left 26.90$^{\circ}$, right 30.93$^{\circ}$; 3) The maximum knee flexion moment showed left 0.363 Nm/kg, right 0.464 Nm/kg, The maximum knee extension moment showed left 0.389 Nm/kg, right 0.463 Nm/kg. The maximum knee adduction moment showed left 0.332 Nm/kg, right 0.379 Nm/kg. The maximum internal rotational moment showed left 0.13 Nm/kg, right 0.140 Nm/kg; 4) The subjects who had varus alignment of the lower extremity had statistically higher in knee adduction moment in mid stance phase; and 5) The subjects who had large foot progression angle had statistically lower in knee adduction moment in late stance phase.

• Journal of the Korean Society of Physical Medicine
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• v.11 no.2
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• pp.53-62
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• 2016

PURPOSE: The purpose of this study was to investigate the effects of a supplementary Ki-hap technique and verbal encouragement on the activation of abdominal muscles during performance of crunch exercise in healthy subjects. METHODS: 93 subjects were randomly allocated to three group, crunch exercise group (CG), crunch exercise with Ki-hap group (CKG), and crunch exercise with Ki-hap and verbal encouragement group (CKVG), with 31 subjects in each group, respectively. The interventions were conducted over three trials in each group, and measurements were performed on each subject by one examiner in three trials. The activation of rectus abdominis (RA), external oblique (EO), and internal oblique (IO) muscles were evaluated using electromyography (EMG) during performance of crunch exercise with non-Ki-hap, Ki-hap and Ki-hap combined with verbal encouragement. RESULTS: Our results showed a significantly greater increase in the EMG patterns of all muscles during performance of crunch exercise in the CKG (p<0.05) compared to the CG and CKVG. The results also showed that there were significantly greater increase in the activation of EO and IO muscles in those of the CKVG (p<0.05) compared with the CG. CONCLUSION: These findings demonstrated that addition of the Ki-hap technique and verbal encouragement during performance of crunch exercise, at the same time, would suggest positive evidence for improving activation of abdominal muscles.

• Journal of Korean Neurosurgical Society
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• v.29 no.8
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• pp.1055-1062
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• 2000

Objectives : Burst fracture of the lower lumbar spine(L3-L5) is rare and has some different features compare to that of thoracolumbar junction. Lower lumbar spine is flexible segments located deeply, and has physiologic lordosis. All of these contribute to making surgical approach difficult. Generally, lower lumbar burst fracture is managed either anteriorly or posteriorly with various fixation and fusion methods. But there is no general guideline or consensus regarding the proper approach for such lesion. We have tried to find out the influencing factors for selecting the surgical approach through the analysis of lower lumbar burst fractures treated for last 4 years(1994.3-1998.3). Method : This study includes 15 patients(male : 10, female : 5, age range 20-59 years with mean age of 36.7 years, L3 : 8 cases, L4 : 5 cases, L5 : 2 cases). Patients were classified into anterior(AO) and posterior operated(PO) groups. We investigated clinical findings, injured column, operation methods, and changes in follow-up radiologic study (kyphotic angle) to determine the considerable factors in selecting the surgical approaches. Results : There were 5 AO and 10 PO patients. Anterior operation were performed with AIF with Kaneda or Z-plate and posterior operation were done with pedicle screw fixation with PLIF with cages or posterolateral fusion. Canal compression was 46.6% in AO and 38.8% in PO. The degree of kyphotic angle correction were 10.7 degree(AO) and 8.5 degree(PO), respectively. There was no statistical difference between anterior and posterior operation group. All patients showed good surgical outcome without complications. Conclusion : Anterior operation provided good in kyphotic angle correction and firm anterior strut graft, but it difficulty arose in accessing the lesions below L4 vertebra. While posterior approach showed less correction of kyphotic angle, it required less time and provided better results for accompanied adjacent lesion and pathology such as epidural hematoma. The level of injury, canal compression, biomechanics, multiplicity, and pathology are considered to be important factors in selection of the surgical approach.

• The Journal of the Korea Contents Association
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• v.13 no.10
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• pp.523-532
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• 2013

When the golf club hits the ground prior to making contact with the golf ball, we define it as 'fat shot'. The aim of this research was to investigate the difference between normal shot and fat shot in golf. Five candidates playing as recreational golfer participated in this research and they were all right-handed people. Time phase between each event, wrist cocking angle, elbow extension-flexion angle, backswing height, pelvis angle, thorax angle, L-GRF, R-GRF, pelvis linear velocity, pelvis angular velocity and COG path were calculated. For statistical analysis the paired T-test was used. An early un-cocking, an early right elbow extension and impact with leaving their weight behind foot were not reasons of fat shot. Backswing height, X-Factor, pelvis angle and thorax rotation angle were not different between normal shot and fat shot. But we could find a pattern of abrupt pelvic movement and weight shift to target direction just before impact in case of fat shot. In addition fat shot showed time-delayed and small value of pelvis linear velocity pattern to upward during downswing phase as against normal shot.

• The Journal of Korean Physical Therapy
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• v.25 no.5
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• pp.239-245
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• 2013

Purpose: Osteoarthritis occurs in many different joints of the body, causing pain, stiffness, and decreased function. The knee is the most frequently affected joint of the lower limb. The aim of this study was to investigate the differences of biomechanics between independent gait and anterior walker dependent gait of patients with osteoarthritis of the knee. Methods: Lower limb joint kinematics and kinetics were evaluated in 15 patients with knee osteoarthritis when walking independently and when walking with an anterior walker. Participants were evaluated in a gait laboratory, with self-selected gait speed and natural arm swing. Results: When walking with a dependent anterior walker, participants walked significantly faster (p<0.01), using a longer stride length (p<0.01), compared to independent gait. When walking with a dependent anterior walker, participants exhibited significantly greater knee flexion/extension motion (p<0.01) and lower knee flexion moment (p<0.05) compared to independent gait. When walking with a dependent anterior walker, participants showed significantly greater peak ankle motion (p<0.01), ankle dorsiflexion/plantarflexion moments (p<0.01), and ankle power generation (p<0.05) compared to independent gait. Conclusion: These biomechanical properties of gait, observed when participants walked with a dependent anterior walker, may be a compensatory response to impaired knee function to allow sufficient power generation for propulsion. Therefore, rehabilitative strategies for patients with osteoarthritis of the knee are needed in order to improve not only knee function but also hip and ankle function.

• Progress in Medical Physics
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• v.2 no.2
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• pp.161-173
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• 1991

A statistical approach was carried out to analyze joint moments acting on the six subjects performing a right-handed seated task. The dynamic task analyzed consisted of moving a hand-held weight of lkg mass back and forth in front of a subject's chest at the shoulder level in an upright seated position. We used experimental data obtained in the Biomechanics Laboratory of the University of Michigan. Based on the acquired data from three trials by each subject, moments were calculated using a 3-dimensional biomechanical model at such articulations as wrist, elbow, shoulder, the third lumbar spine, hip, knee, and ankle joints. The linear correlation and the two way analysis of variance were applied to the calculated joint moments in order to investigate inter-subject and inter-trial varations. The results obtained showed that the largest magnitude and deviation of moment was found at the third lumbar spine, that any linear relationship could not be found between moment and its equivalents attempted in this study, and that the maximum value and deviation of moment acting on each joint were statistically the same for all three trials but those were statistically not the same for all six subjects.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.2
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• pp.169-176
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• 2015

The mechanical properties of living tissues have been major subjects of interest in biomechanics. In particular, the characteristics of very soft materials such as the brain have not been fully understood because experiments are often severely limited by ethical guidelines. There are increasing demands for studies on remote medical operations using robots. We conducted compression tests on brain-like specimens made of gelatin to find substitutes with the mechanical properties of brain tissues. Using a finite element analysis, we compared our experimental data with existing data on the brain in order to establish material models for brain tissues. We found that our substitute models for brain tissues effectively simulated their mechanical behaviors.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.10
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• pp.1139-1145
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• 2014

Creation of a human skeleton model and characterization of the variation in the bone shape are fundamentally important in many applications of biomechanics. In this paper, we present a parametric shape modeling method for femurs that is based on extracting the main parameter of variations of the femur shape from a 3D model database by using statistical shape analysis. For this shape analysis, principal component analysis (PCA) is used. Application of the PCA to 3D data requires bringing all the models in correspondence to each other. For this reason, anatomical landmarks are used for guiding the deformation of the template model to fit the 3D model data. After subsequent application of PCA to a set of femur models, we calculate the correlation between the dominant components of shape variability for a target population and the anatomical parameters of the femur shape. Finally, we provide tools for visualizing and creating the femur shape using the main parameter of femur shape variation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.10
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• pp.953-959
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• 2013

In this study, a multibody dynamic model of the cervical spine was developed for a virtual in-vitro cadaveric experiment. The dynamic cervical spine model was reconstructed based on Korean CT images and the material properties of joints and soft tissue obtained from in-vitro experimental literature. The model was validated by comparing the inter-segmental rotation, multi-segmental rotations, load-displacement behavior, ligament force, and facet contact force with the published in-vitro experimental data. The results from the model were similar to published experimental data. The developed dynamic model of the cervical spine can be useful for injury analysis to predict the loads and deformations of the individual soft-tissue elements as well as for virtual in-vitro cadaveric experiments.