• Clinics in Shoulder and Elbow
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• v.14 no.1
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• pp.35-45
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• 2011

Purpose: The purpose of this study was to document the structural features of the tendinous portions within the non-pathologic subscapularis muscle by performing high resolution MR imaging of the shoulder. Materials and Methods: Between April 2007 and May 2010, we retrospectively obtained the MR scans of 88 consecutive young patients (88 shoulders) who were in their twenties. MRI and MR arthrography were performed using a 3.0-T system for the evaluation of glenohumeral instability and nonspecific shoulder pain. None of the patient in this study had any evidence of injury to the tendon or muscle belly of the subscapularis. On MR images, we recorded the transverse length of a stout tendinous band and the total tendinous portion of the subscapularis. In addition, we recorded the number of intramuscular tendinous slips of the susbscapularis. Results: The mean transverse length of the tendinous band was 15.0 mm (range: 8 to 20 mm). The mean transverse length of the total tendinous portion was 48.9 mm (range: 40 to 60 mm). The number of intramuscular tendinous slips on the base of the glenoid fossa was 3 in 20 (22.72%), 4 in 45 (51.14%) and 5 in 23 shoulders (26.14%). On the lateral portion, the intramuscular tendinous slips became gradually rounder and thicker and they gave converge in the superior direction. Conclusion: In this study, the structural features of the tendinous portions of the subscapularis on the MR scans were identified. This will in return give good justification for the lines to be pulled during biomechanical stimulation and also for the surgical approach to restore the biomechanical function.

• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.2
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• pp.228-235
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• 2004

The development and proliferation of the mandibular condyle can be altered by changes in the biomechanical environment of the temporomandibular joint. The biomechanical loads were varied by feeding diets of different consistencies. The purpose of the present study was to determine whether changes of masticatory forces by feeding a soft diet can alter the trabecular bone morphology of the growing mouse mandibular condyle, by means of micro-computed tomography. Thirty-six female, 21 days old, C57BL/6 mice were randomly divided into two groups. Mice in the hard-diet control group were fed standard hard rodent pellets for 8 weeks. The soft-diet group mice were given soft ground diets for 8 weeks and their lower incisors were shortened by cutting with a wire cutter twice a week to reduce incision. After 8 weeks all animals were killed after they were weighed. Following sacrifice, the right mandibular condyle was removed. High spatial resolution tomography was done with a Skyscan Micro-CT 1072. Cross-sections were scanned and three-dimensional images were reconstructed from 2D sections. Morphometric and nonmetric parameters such as bone volume(BV), bone surface(BS), total volume(TV), bone volume fraction(BV/TV), surface to volume ratio(BS/BV), trabecular thickness(Tb. Th.), structure model index(SMI) and degree of anisotropy(DA) were directly determined by means of the software package at the micro-CT system. From directly determined indices the trabecular number(Tb. N.) and trabecular separation(Tb. Sp.) were calculated according to parallel plate model of Parfitt et al.. After micro-tomographic imaging, the samples were decalcified, dehydrated, embedded and sectioned for histological observation. The results were as follow: 1. The bone volume fraction, trabecular thickness(Tb. Th.) and trabecular number(Tb. N.) were significantly decreased in the soft-diet group compared with that of the control group (p<0.05). 2. The trabecular separation(Tb. Sp.) was significantly increased in the soft-diet group(p<0.05). 3. There was no significant differences in the surface to volume ratio(BS/BV), structure model index(SMI) and degree of anisotropy(DA) between the soft-diet group and hard-diet control group (p>0.05). 4. Histological sections showed that the thickness of the proliferative layer and total cartilage thickness were significantly reduced in the soft-diet group.

• Journal of the korean academy of Pediatric Dentistry
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• v.37 no.2
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• pp.246-251
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• 2010

Impactions can occur because of malpositioning of the tooth bud or obstruction in the path of eruption. However, the exact mechanism is still unknown. The impaction of mandibular first molar is rare with prevalence rates of 0.01~0.25%, but it is important to deimpact the tooth as soon as possible to avoid complications such as dental caries, root resorption, and periodontal problems on the adjacent teeth. Several biomechanical strategies have been proposed for uprighting mesially tipped mandibular first molars. However, most of these have had problems with movement of the anchorage unit because of the reciprocal force. The recent development of skeletal anchorage system(SAS) allows direct application of precise force systems to the target tooth or segment, producing efficient tooth movement in a short time. In this case, an impacted mandibular left first molar with dilacerated roots was treated with a miniplate, which provided skeletal anchorage to upright the tooth. The miniplate was installed in the mandibular ramus, and 10 months after the application of orthodontic force, the impacted tooth was exposed in the oral cavity and uprighted. At this point, the mandibular left first molar was included in the orthodontic appliance with fixed mechanotherapy, the tooth could achieve a normal occlusion. Therefore, the use of SAS simplified the orthodontic procedures and reduced the orthodontic treatment period, and had few side effects.

• Korean Journal of Applied Biomechanics
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• v.26 no.1
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• pp.21-30
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• 2016

Objective: This study aimed to examine the characteristics of joint kinematics and synchronicity of rowing motion between elite and non-elite rowers. Methods: Two elite and two non-elite rowers performed rowing strokes (3 trials, 20 strokes in each trial) at three different stroke rates (20, 30, 40 stroke/min) on two stationary rowing ergometers. The rowing motions of the rowers were captured using a 3-dimensional motion analysis system (8-infrared camera VICON system, Oxford, UK). The range of motion (RoM) of the knee, hip, and elbow joints on the sagittal plane, the lead time ($T_{Lead}$) and the drive time $T_{Drive}$) for each joint, and the elapsed time for the knee joint to maintain a fully extended position ($T_{Knee}$) during the stroke were analyzed and compared between elite and non-elite rowers. Synchronicity of the rowing motion within and between groups was examined using coefficients of variation (CV) of the $T_{Drive}$ for each joint. Results: Regardless of the stroke rate, the RoM of all joints were greater for the elite than for non-elite rowers, except for the RoMs of the knee joint at 30 stroke/min and the elbow joint at 40 stroke/min (p < .05). Although the $T_{Lead}$ at all stroke rates were the same between the groups, the $T_{Drive}$ for each joint was shorter for the elite than for the non-elite rowers. During the drive phase, elite rowers kept the fully extended knee joint angle longer than the non-elite rowers (p < .05). The CV values of the TDrive within each group were smaller for the elite compared with non-elite rowers, except for the CV values of the hip at all stroke/min and elbow at 40 stroke/min. Conclusion: The elite, compared with non-elite, rowers seem to be able to perform more powerful and efficient rowing strokes with large RoM and a short $T_{Drive}$ with the same $T_{Lead}$.

• Korean Journal of Applied Biomechanics
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• v.20 no.4
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• pp.469-477
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• 2010

The purpose of this study was to evaluate the effects of insole-equipped ankle-foot-orthoses (AFO) on gait. 10 healthy males who had no history of injury in the lower extremity participated in this study as the subjects. The foot of each subject was first scanned, and the insole fit to the plantar was made using BDI-PCO(Pedcad Gmbh, Germany). The subject then was made to walk on a treadmill under four experimental conditions: 1) normal walking, 2) walking wearing AFO, 3) walking wearing AFO equipped with the insole, 4) walking wearing pneumatic-ankle-foot-orthosis (pAFO) equipped with the insole. During walking, foot pressure data such as maximum force, contacting area, peak pressure, and mean pressure was collected using Pedar-X system (Novel Gmbh, Germany) and EMG activity of lower limb muscles such as gastrocnemius medial head, gastrocnemius lateral head, and soleus was recorded using MP150 EMG module (BIOPAC System Inc., USA). Collected data was then analyzed using paired t-test in order to investigate the effects of the insole. As a result of the analysis, when insole was equipped, overall contacting area was increased while both the highest peak pressure and the mean pressure were significantly decreased, and EMG activity of the lower limb muscles was decreased. On the contrary, the cases of wearing AFO showed the decreased contacting area and the increased pressures. Therefore, the AFO equipped with a proper insole fit well to the foot can help comfortable walking by spreading the pressure over the entire plantar.

• Journal of Convergence for Information Technology
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• v.9 no.8
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• pp.140-147
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• 2019

The purpose of this study is to find biomechanical parameters for optimal shoes production through an ergonomic usability assessment of five existing types of shoes preferred by B-BOY. Ten experts and ten non-experts participated in the experiment, and 12 infrared cameras (Qualis, Oqus), force plate (Kistler, 9286AA) and foot pressure plate (Zebris Gmbh, Zebris PDM-System) were used to obtain the data. The results of the study are as follows. First, P shoes with a friction coefficient of 0.38 and a free moment of 0.32 N/m/kg are desirable in terms of traction capability and safety. Second, on the cushion, it was found that the N shoes 2.51 N, sec/kg and non-expert, and 2.86 N and sec/kg were suitable. Third, it is deemed appropriate for C shoes with a forefoot average pressure of 10.11 KPa (right), 10.05 KPa (left), and V shoes with a rearfoot average pressure of 8.4 KPa (right) and 8.36 KPa (left). In conclusion, the combination of the structure and material of V shoes should be developed for traction and stability, N shoes for cushion, and walking balance for C and V shoes.

• Korean Journal of Applied Biomechanics
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• v.21 no.4
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• pp.437-447
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• 2011

In this study, the lower limbs joints were analyzed for features based on the biomechanical characteristics of landing techniques according to height and landing on the ground type (flats and downhill). In order to achieve the objectives of the study, changes were analyzed in detail contents such as the height and form of the first landing on the ground at different angles of joints, torso and legs, torso and legs of the difference in the range of angular motion of the joint, the maximum angular difference between joints, the lower limbs joints difference between the maximum moment and the difference between COM changes. The subjects in this study do not last six months did not experience joint injuries 10 males in 20 aged were tested. Experimental tools to analyze were the recording and video equipment. Samsung's SCH-650A model camera was used six units, and the 2 GRF-based AMTI were used BP400800 model. 6-unit-camera synchronized with LED (photo cell) and Line Lock system were used. the output from the camera and the ground reaction force based on the data to synchronize A/D Syc. box was used. To calculate the coordinates of three-dimensional space, $1m{\times}3m{\times}2m$ (X, Y, Z axis) to the size of the control points attached to the framework of 36 markers were used, and 29 where the body was taken by attaching a marker to the surface. Two kinds of land condition, 40cm and 60cm in height, and ground conditions in the form of two kinds of flat and downhill slopes ($10^{\circ}$) of the landing operation was performed and each subject's 3 mean two-way RM ANOVA in SPSS 18.0 was used and this time, all the significant level was set at a=.05. Consequently, analyzing the landing technique as land form and land on the ground, the changes of external environmental factors, and the lower limbs joints' function in the evaluation were significantly different from the slopes. Landing of the slop plane were more load on the joints than landing of plane. Especially, knee extensor moment compared to the two kinds of landing, slopes plane were approximately two times higher than flat plane, and it was statistical significance. Most of all not so much range of motion and angular velocity of the shock to reduce stress was important. In the further research, front landing as well as various direction of motion of kinetic, kinetic factors and EMG variables on lower limbs joints of the study in terms of injury-prevention-approach is going to be needed.

• Korean Journal of Applied Biomechanics
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• v.17 no.2
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• pp.177-185
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• 2007

Even though there were no clear definitions of the short game and short game distance, short game capability is crucial for a good golf score. Generally, chip shot and pitch shot are regarded as two principal components of the short game. Chip shot is a short, low trajectory shot played to the green or from trouble back into play. Pitch shot is a high trajectory shot of short length. Biomechanical studies were conducted usually to analyze full swing and putting motions. The purpose of the study was to reveal the kinematical differences between professional golfers' 30 yard $53^{\circ}wedge$ chip shot and $56^{\circ}wedge$ pitch shot motions. Fifteen male professional golfers were recruited for the study. Kinematical data were collected by the 60 Hz three-dimensional motion analysis system. Statistical comparisons were made by paired t-test, ANOVA, and Duncan of the SPSS 12.0K with the $\alpha$ value of .05. Results show that both the left hand and the ball were placed left of the center of the left and right foot at address. The left hand position of the chip shot was significantly left side of that of the pitch shot. But the ball position of the pitch shot was significantly right side of that of the chip shot. All body segments aligned to the left of the target line, open, at address. Except shoulder, there were no significant pelvis, knee, and feet alignment differences between chip shot and pitch shot. These differences at address seem for the ball height control. Pitch shot swing motions(the shoulder and pelvis rotation and the club head travel distance) were significantly bigger than those of the chip shot. Club head velocity of the pitch shot was significantly faster than that of the chip shot at the moment of impact. This was for the same shot length control with different lofted clubs. Swing motion differences seem mainly caused by the same shot length control with different ball height control.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.10
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• pp.1147-1155
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• 2014

Biomechanical models are often used to predict muscle and joint forces in the human body. For estimation of muscle forces, the body and muscle properties have to be known. However, these properties are difficult to measure and differ from person to person. Therefore, it is necessary to predict the change in muscle forces depending on the body and muscle properties. The objective of the present study is to develop a numerical procedure for estimating the muscle forces in the human lower extremity under uncertainty of body and muscle properties during rising motion from a seated position. The human lower extremity is idealized as a multibody system in which eight Hill-type muscle force models are employed. Each model has four degrees of freedom and is constrained in the sagittal plane. The eight muscle forces are determined by minimizing the metabolic energy consumption during the rising motion. Uncertainty analysis is performed using a first-order reliability method. The one-standard-deviation range of agonistic muscle forces is calculated to be about 150-300 N.

• Journal of Korean Physical Therapy Science
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• v.8 no.1
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• pp.893-906
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• 2001

The purposes of this study were to compare pelvic tilt. range of motion(ROM) of hip rotation, and leg length difference before and after manipulation and to investigate correlation between changes of each variables after manipulation of sacroiliac pint in 31 low back pain patients(11 males, 20 females) with sacroiliac pint dysfunction. The sacroiliac pint of patients was manipulated on the side of anterior pelvic tilt, using the technique described by Stoddard(1962) and Greenmann (1996). I used this technique because it usually eliminated sacroiliac Pint dysfunction in one treatment session. SPSS for window computer system was used to analyze the data. Also t-test was performed for comparison of the variables before and after manipulation, and Pearson product-moment correlation analysis and regression analysis were performed for changes of each variables after manipulation. The result were as follows: 1. The pelvic tilt after manipulation was significantly decreased(mean=$2.79^{\circ}$) compared with the pelvic tilt before manipulation(p=.001). 2. The PROM of hip internal rotation ipsilateral to anterior pelvic tilt after manipulation significantly decreased (mean = $1.88^{\circ}$) compared with hip internal rotation before manipulation (p=.008). The PROM of hip internal rotation ipsilateral to posterior pelvic tilt after manipulation significantly increased(mean = $1.29^{\circ}$) compared with hip internal rotation before manipulation (p=.029). 3. The PROM of hip external rotation ipsilateral to anterior pelvic tilt after manipulation significantly increased(mean=$2.42^{\circ}$) compared with the hip external rotation before manipulation(p=$2.42^{\circ}$) compared with the hip external rotation ipsilateral to posterior pelvic tilt after manipulation significantly decreased(mean = $1.84^{\circ}$) compared with the hip external rotation before manipulation (p=.008). 4. Leg length difference after manipulation significantly decreased(mean=2.15 mm) compared with leg length difference before manipulation (p=.008). Regression analysis revealed that a fair correlation was found between change in leg length difference and change in anterior pelvic tilt after manipulation(p=.009). 5. Pearson product-moment correlation coefficient was used to assess differences of the variables after manipulation. A fair correlation was found between change in leg length difference and change in anterior pelvic tilt after manipulation(r=.462, p<.01). A fair correlation was found between change in anterior pelvic tilt and change in hip internal rotation ipsilateral to anterior pelvic tilt(r=.397, p<.05) and between change in anterior pelvic tilt and change in hip external rotation ipsilateral to anterior pelvic tilt(r=.516, p<.01). A fair correlation was found between change in posterior pelvic tilt and changes in hip internal rotation ipsilateral to posterior pelvic tilt (r=.441, p<.05) and between change in posterior pelvic tilt and change in hip external rotation ipsilateral to posterior pelvic tilt(r=.361, p<.05). A fair correlation was found between change in hip internal rotation ipsilateral to anterior pelvic tilt and change in hip external rotation ipsilateral to posterior pelvic tilt(r=.388, p<.05) and between change in hip internal rotation ipsilateral to posterior pelvic tilt and change in hip internal rotation ipsilateral to anterior pelvic tilt(r=.426. p<.05).