• Journal of the Korean Society of Physical Medicine
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• v.8 no.1
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• pp.41-48
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• 2013

PURPOSE: This study was to determine the effect of the plane of movement (sagittal plane vs. scapular plane) and shoulder flexion angle ($90^{\circ}$ vs. $130^{circ}$) during scapular protraction exercises in healthy subjects by investigating the elecromyographic (EMG) activities of the serratus anterior (SA), upper trapezius (UT), and pectoralis major (PM). METHODS: Twenty-one healthy subjects participated in this study. Subjects performed maximal scapular protraction at the $90^{\circ}$ or $130^{\circ}$ shoulder flexion angles in the sagittal or scapular planes. Surface EMG was recorded from the SA and UT, and PM muscles. Dependent variables were examined by 2 (plane) ${\times}$ 2 (angle) repeated measures of analysis of variance (ANOVA). RESULTS: Significantly increased EMG activities in the SA and UT were found during scapular protraction exercise at the $130^{\circ}$ shoulder flexion angle in the sagittal and scapular plane. Also, EMG activity of the PM significantly decreased at the $130^{\circ}$ shoulder flexion angle in the sagittal plane and the $90^{\circ}$ and $130^{\circ}$ shoulder flexion in the scapular plane. CONCLUSION: we recommend scapular protraction exercise at the $90^{\circ}$ shoulder flexion in the sagittal plane to selectively strengthen the SA muscle with limitation of upper trapezius activity and at the $130^{\circ}$ shoulder flexion in the scapular plane to selectively strengthen the SA muscle with limitation of pectoralis major activity.

• Korean Journal of Applied Biomechanics
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• v.30 no.3
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• pp.275-283
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• 2020

Objective: The purpose of this study was to investigate the effect pf flexibility of hip flexor muscles on a conventional deadlift movement. Method: Eighteen healthy male were participated in this study and were divided into normal group (NG: age: 24.0±1.8 yrs, height: 174.5±2.37 cm, body mass: 74.4±5.5 kg, 1RM: 138.0±23.8 kg) and restricted group (RG: age: 24.6±1.7 yrs, height: 171.5±5.3 cm, body mass: 74.0±5.7 kg, 1RM: 137.5±18.3 kg) by Thomas test, which measure flexibility of hip flexor muscles. A 3-dimensional motion analysis with 8 infrared cameras and 3 channels of EMG was performed in this study. A two-way ANOVA (group x load) with repeated measure was used for statistical verification. The significant level was set at α=.05. Results: RG revealed significantly increased muscle activation in erector spinae on 70% and 90% of 1RM and decreased muscle activation in gluteus maximus on 90% of 1RM compared to NG (p<.05). For the muscle activation ratio for agonist to synergist, erector spinae showed the difference in 90% of 1RM while hamstring was observed differences in all loads (p<.05). Conclusion: Our results indicated that hip flexibility affects conventional deadlift movement. Therefore, it is necessary to assess the flexibility of the hip flexor muscles before performing the movement and, as needed, to train to address the lack of flexibility.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.12
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• pp.1489-1495
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• 2012

In this study, we perform the structural analysis of a floating offshore wind turbine tower by considering the dynamic response of the floating platform. A multibody system consisting of three blades, a hub, a nacelle, the platform, and the tower is used to model the floating wind turbine. The blades and the tower are modeled as flexible bodies using three-dimensional beam elements. The aerodynamic force on the blades is calculated by the Blade Element Momentum (BEM) theory with hub rotation. The hydrostatic, hydrodynamic, and mooring forces are considered for the platform. The structural dynamic responses of the tower are simulated by numerically solving the equations of motion. From the simulation results, the time history of the internal forces at the nodes, such as the bending moment and stress, are obtained. In conclusion, the internal forces are compared with those obtained from static analysis to assess the effects of wave loads on the structural stability of the tower.

• Journal of The Korean Society of Integrative Medicine
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• v.3 no.1
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• pp.81-90
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• 2015

Purpose: The purpose of this study was to investigate any visible difference in shoulder stability muscle activity along the bending angle($70^{\circ}$, $90^{\circ}$, $110^{\circ}$) to perform the open kinetic chain(OKC) and closed kinetic chain(CKC) exercise. Method: This study was performed on normal 20 males subjects. Exercise was carried out in two ways OKC and CKC. Shoulder stability muscles are examined activity in the bending angles. In the OKC and CKC exercise to subjects with stretched out waist straightened, and than push forward the shoulder. Muscular activation was examined using the WEMG-8. Result: The results of this study were as follows. 1. Only in the trapezius muscle, it showed specific interaction between exercise methods and angles. When it comes to muscle activity, there was no significant difference in all muscles except for the anterior fibers of the deltoid muscle during both CKC and OKC exercise. 2. The average value of maximum muscle activity was significantly increased with increasing order of angles. But in CKC exercise, the muscle activity of infraspinatus tended to decrease with increasing angles. Conclusion: To summarize the research results, the muscle activity in upper fibers of the trapezius, anterior fibers of the deltoid, and serratus anterior was significantly different depending on the angle of the shoulder in both CKC and OKC exercise.

• Journal of The Korean Society of Integrative Medicine
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• v.8 no.4
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• pp.171-181
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• 2020

Purpose : The purpose of this study was to investigate the effects of curl-up and proprioceptive neuromuscular facilitation (PNF) neck flexion exercises on stroke patients' trunk muscle activity, ability to control the trunk, and balance by comparing two exercise methods. Methods : The study involved patients who had been diagnosed with stroke based on the results of computerized tomography or magnetic resonance imaging at O Hospital in Daegu, South Korea, between January and July 2020. In total, 30 subjects were selected and by flipping a coin, randomly assigned to an experimental group (n=15) that performed PNF neck flexion exercises and a control group (n=15) that performed curl-up exercises. Both groups received traditional rehabilitation therapy for 30 minutes a day five times a week for a six-week period. In addition, the experimental group performed PNF neck flexion exercises and the control group curl-up exercises for 15 minutes a day five times a week over the same period. The subjects' muscle activity in the rectus abdominis (RA), external oblique (EO), and internal oblique (IO) were measured before and after the experiment. The subjects' trunk impairment scale (TIS) and Berg balance scale (BBS) scores were also assessed. Paired t test was performed to measure the amount of statistical change before and after intervention in both groups. An independent sample T test was performed to measure the amount of statistical change between the two groups. Results : Both groups experienced statistically significant increases in their RA, IO and EO muscle activity, total TIS scores, and total BBS scores after the intervention. No statistically significant differences in the changes before and after the intervention were found for any of the resulting values between the two groups. Conclusion : A comprehensive review of the study's results suggested that neck flexion exercises using the PNF irradiation concept and curl-up exercise are effective in increasing stroke patients' abdominal muscle activity and improving trunk control ability and balance in chronic stroke patients.

• PNF and Movement
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• v.18 no.3
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• pp.333-341
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• 2020

Purpose: The purpose of this study was to investigate the effect of open and closed kinetic chain exercises with a sling on neck flexor thickness during chin-in movement in office workers with forward head posture. Methods: Thirty-one selected subjects randomly performed chin-in movement in open kinetic chain and closed kinetic chain exercises using a sling. All subjects were measured for their neck flexor thickness using ultrasound measurement equipment during the performance of chin-in movement in open and closed kinetic chain exercised. A paired t-test was used to compare the thickness of the total neck flexor, superficial, and deep neck flexor, respectively, between open and closed kinetic chain exercises with chin-in movement. Results: The thickness of the superficial neck flexor diminished in size more greatly during the chin-in movement with the closed kinetic chain than the open kinetic chain, but this was not a statistically significant difference (p > 0.05). On the other hand, the thickness of the total neck flexor and deep neck flexor had more greatly increased during the chin-in movement with the closed kinetic chain than the open kinetic chain, and this was a statistically significant differences (p < 0.05). Conclusion: This study suggested that chin-in movement with a closed kinetic chain is more effective in activating the deep neck flexor than the open kinetic chain. Thus, we believe that the closed kinetic chain exercise using a sling is an effective intervention to correct the postural alignment of individuals with forward head posture.

• Korean Journal of Applied Biomechanics
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• v.33 no.4
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• pp.147-154
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• 2023

Objective: This study aimed 1) to compare the Landing Error Scoring System (LESS) score and movement patterns during landing of the lesser dorsiflexion range of motion (LDFROM) group to that with the greater dorsiflexion range of motion group, and 2) to identify the correlation between the weight-bearing dorsiflexion range of motion (WBDF ROM), LESS score, and movement patterns during landing. Method: Fifty health adults participated in this study. WBDF ROM was measured using the weight bearing lunge test while movement patterns during landing was assessed using the LESS. The joint angles of the ankle, knee and hip joints during landing were analyzed using the 2D video analysis. After mean value of WBDF ROM was calculated, participants were divided into two groups (GDFROM and LDFROM) based on the mean value. The Mann-Whiteny 𝒰 test was used to identify differences in movement strategies during landing between two groups and the Pearson's correlation analysis was performed to determine relationships between WBDF ROM and movement strategies. Results: The LDFROM group showed the poorer LESS score and stiffer landing kinematics during landing compared to the GDFROM group (p<0.05). In addition, DFROM was significantly related to the LESS score and landing kinematics (p<0.05) except for total hip excursion (p=0.228). Conclusion: Our main findings showed that the LDFROM group had poorer landing quality and stiffer landing movements compared to the GDFROM group. In addition, increase of WBDF ROM significantly improved landing quality and soft-landing movements. To reduce shock during landing such as ground reaction forces, individuals need to better utilize WBDF ROM and lower extremity movements based on our findings. Therefore, intervention programs for safer landings should include exercises that increase WBDF ROM and utilize eccentric contraction.

• The Journal of the Convergence on Culture Technology
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• v.10 no.1
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• pp.19-23
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• 2024

Patients with amputations of both hands need prosthetic hands that serve both cosmetic and functional purposes, and research on prosthetic hands using electromyography of remaining muscles is active, but there is still the problem of high cost. In this study, an artificial prosthetic hand was manufactured and its performance was evaluated using low-cost parts and software such as a surface electromyography sensor, machine learning software Edge Impulse, Arduino Nano 33 BLE, and 3D printing. Using signals acquired with surface electromyography sensors and subjected to digital signal processing through Edge Impulse, the flexing movement signals of each finger were transmitted to the fingers of the prosthetic hand model through training to determine the type of finger movement using machine learning. When the digital signal processing conditions were set to a notch filter of 60 Hz, a bandpass filter of 10-300 Hz, and a sampling frequency of 1,000 Hz, the accuracy of machine learning was the highest at 82.1%. The possibility of being confused between each finger flexion movement was highest for the ring finger, with a 44.7% chance of being confused with the movement of the index finger. More research is needed to successfully develop a low-cost prosthetic hand.

• Journal of the Society of Naval Architects of Korea
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• v.49 no.2
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• pp.109-115
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• 2012

Slamming phenomenon may occur when a ship navigates a high sea region, where the response of ship can be expected as elastic behaviour and the resultant wave loads may increase. In this paper, numerical analysis of ship motions and wave loads including momentum slamming was performed using the strip theory with regular waves. In order to analyze the effect of slamming force on the global ship motions, time histories of each mode of displacement and forces were simulated by using Newmark-beta time integration scheme. The added mass and damping coefficients calculated by Lewis form method were compared with the results of given references. For verification of numerical results, the motion RAOs of a S175 containership were calculated as an example of application and time histories of respective displacement and vertical bending moment were compared with the results of ITTC workshop benchmark test.

• Journal of The Korean Society of Integrative Medicine
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• v.5 no.4
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• pp.31-39
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• 2017

Purpose : The purpose of this study was to examine the effects of short neck flexor strengthening in proprioceptive neuromuscular facilitation and neuromuscular electrical stimulation on swallowing function in patients with chronic stroke and to provide basic data for swallowing rehabilitation in stroke patients. Method : The study involved 30 chronic stroke patients who visited ${\bigcirc}{\bigcirc}$ General Hospital in Daegu Metropolitan City between March and July, 2017. The subjects were randomly assigned to either an experimental group (n=15) or a control group (n=15). Both groups underwent traditional swallowing rehabilitation therapy for 30 minutes five times a week over a six-week period. The experimental group performed short neck flexor exercises, which are part of the proprioceptive neuromuscular facilitation, for 30 minutes three times a week over a six-week period. The control group performed neuromuscular electrical stimulation for 30 minutes three times a week over a six-week period. Based on its results, changes in the patients' swallowing function and degree of food intake were analyzed. Result : In terms of the ASHA NOMS scale and new VFSS scale, the experimental group and the control group showed statistically significant changes in ten sub-items and six sub-items, respectively. Statistically significant differences in one sub-item were found between the groups. Conclusion : PNF-based short neck flexion exercise appear to be effective at improving swallowing function of stroke patients with dysphagia.