• 한국체육학회지인문사회과학편
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• v.58 no.2
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• pp.405-416
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• 2019

This study aimed to identify the efficiency of short track-related sports injury prevention program consisted of muscle strength and neuromuscular training on non-contact injury incidence and characteristics in knee and ankle joints and low back for elite short track speed skaters. Twenty-five short track athletes who belonged to G-City Team were participated in this study from Nov. 2017 to Jul. 2018. Information on their sports injuries occurred were collected and injury prevention program was applied in their warm-up every training sessions and competition. Also their symptom-level of knee and ankle joint and low back were measured by using OSTRC overuse injury questionnaire and Cumberland ankle instability(CAIT). The injury incidence rate after application of prevention program was 2.79 injuries/1,000 hour exposures(HEs), which was lower than before (3.04 injuries/1,000HEs). The OSTRC score (30.89±28.34 and 23.84±23.61, respectively) in knee and low back after application of prevention program were lower than before (58.47±26.77 and 52.36±21.55, respectively), and the CAIT score (13.47±6.07) in ankle joint after application of program was higher than before (16.26±7.28), which means that their symptom-level was alleviated with sports injury prevention program. In conclusion, the sports injury prevention program designed for short track's motion and characteristic can have positive influences on the occurrence of non-contact injury for short track speed skaters.

• Korean Journal of Applied Biomechanics
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• v.25 no.2
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• pp.175-182
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• 2015

Objective : The purpose of this study was to investigate difference in fascicle behavior of the medial gastrocnemius during the locomotion with varying intensities, such as gait and one-legged and two-legged vertical jumping. Methods : Six subjects (3 males and 3 females; age: $27.2{\pm}1.6yrs.$, body mass: $62.8{\pm}9.8kg$, height: $169.6{\pm}8.5cm$) performed normal gait (G) at preferred speed and maximum vertical jumping with one (OJ) and two (TJ) legs. While subjects were performing the given tasks, the hip, knee and ankle joint motion and ground reaction force was monitored using a 8-infrared camera motion analysis system with two forceplates. Simultaneously, electromyography of the triceps surae muscles, and the fascicle length of the medial gastrocnemius were recorded using a real-time ultrasound imaging machine. Results : Comparing to gait, the kinematic and kinetic parameters of TJ and OJ were found to be significantly different. Along with those parameters, change in the medial gastrocnemius (MG) muscle-tendon complex (MTC) length ($50.57{\pm}6.20mm$ for TJ and $44.14{\pm}5.39mm$ for OJ) and changes in the fascicle length of the MG ($18.97{\pm}3.58mm$ for TJ and $20.31{\pm}4.59mm$ for OJ) were observed. Although the total excursion of the MTC and the MG fascicle length during the two types of jump were not significantly different, however the pattern of length changes were found to be different. For TJ, the fascicle length maintained isometric longer during the propulsive phase than OJ. Conclusion : One-legged and two-legged vertical jumping use different muscle-tendon interaction strategies.

• Korean Journal of Applied Biomechanics
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• v.17 no.2
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• pp.113-121
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• 2007

The purpose of this study was to determine the effect of three different plates($0^{\circ}$, $10^{\circ$}, $20^{\circ}$)under heels on the lower limb muscles and erector spinae during squat exercise. Ten high school korean traditional wrestling players(age: $18.5{\pm}0.7$, weight: $1972.2{\pm}128.5N$, height: $177.8{\pm}6.0cm$, weight of barbell: $1004.5{\pm}132.4N$) performed squat exercise using three different tilting plates under heels at a cadence of 40beats/sec with 80% one repetition maximum load. Surface electrodes were placed on the participants' left and right erector spinae, and rectus femoris, vastus medialis, vastus lateralis, tibialis anterior, biceps femoris, medial gastrocnemius, and lateral gastrocnemius in the right lower extremity. One S-VHS camcorder(Panasonic AG456, 60fields/s) was placed 10m to the side of the participant. To synchronize the video and EMG data, a synchronization unit was used for this study. Average and Peak IEMG values were determined for each participant. For each variable, a one-way analysis of variance was used to determine whether there were significant differences among three different tilting plates under heels. When a significant difference was found in plates type, post hoc analyses were performed using the Tukey procedure. A confidence level of p<.05 was used to determine statistical significance. As a result of this study, maximum nEMG values of the tibialis anterior in $0^{\circ}$ plates was significantly higher than the corresponding values for the other plates during the knee extension. This increased activation in the tibialis anterior muscle indicates an increase in displacement of center of gravity of body. It is very likely that additional muscle activation are needed to stop the forward and backward movement. The results also showed that muscular activities of quadriceps femoris and erector spinae were decreased with increasing angle of plates. This suggests that increasing angle of plate may help to sustain the balance and posture of squat exercise. It is considered that very few significant differences were found among three different plates($0^{\circ}$, $10^{\circ}$, $20^{\circ}$) since elite players with much experience in squat exercise, were chosen as a participant of this study. In order to obtain meaningful results regarding the tilting angle of heel plates in squat exercise, kinetic and 3D kinematic analysis will be needed in the future study.

• Korean Journal of Applied Biomechanics
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• v.18 no.1
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• pp.107-115
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• 2008

The purpose of this study was to investigate muscle activity and vertical ground reaction force(F) in children with Down syndrome(DS) during vertical jump. Six DS and one healthy child performed vertical jump. Four muscles(Biceps femoris, Rectus femoris, Tibialis anterior & Gastrocnemius) and F were analyzed. Gastrocnemius in DS showed lower muscle activity in a propulsive phase. Impulse during 0.3sec before toe-off in DS displayed lower value than that in the healthy child. The second peak of F in DS occurred later than that in the healthy child, so DS performed landing with their knee more flexed. The first and second peak of F and loading rate to the second peak of F in DS showed lower value than those in the healthy child. Therefore, DS might have lower ability to absorb the force while landing from a vertical jump.

• Journal of the Korean Academy of Clinical Electrophysiology
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• v.8 no.2
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• pp.25-31
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• 2010

Purpose : The purpose of this study was to investigate knee muscle strength, balance, and proprioception by walking while giving weight to the ankle joint at a load of 0%, 10%, and 15% gradient on a treadmill. Methods : Twenty-four subjects were divided into three groups. Group A walked on a 0% gradient while giving weight to the ankle joint as a load. Group B walked on a 10% gradient while giving weight to the ankle joint as a load. Group C walked on a 15% gradient while giving weight to the ankle joint as a load. This was performed three times per week for four weeks. The walking speed was set at 4km/hour and the walking time was set at 20 minutes. Measurements were performed before and after the experiment. Biodex medical system and Balance system SD were used as measuring instruments. Results : There was no significant difference between the gradients in muscle strength, balance and proprioception. However, there were differences in pretest and posttest measurements for muscle strength, balance and proprioception in each gradient. In particular, the gradient of 10% showed a significant difference. Conclusion : According to the results of this study, to use a 10% gradient is effective when walking while giving weight to the ankle joint as a load.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.11
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• pp.5019-5026
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• 2011

The purpose of this study was to investigate the effect of the increased sympathetic outflow on the changes of muscle tone and central nervous system excitability in the chronic stroke patients. This study was conducted from October 12th 2009 to December 4th 2009. 30 patients with chronic hemiplegia for at least 6 months were participated. Before and during the mental arithmetic, static handgrip and post-handgrip ischemia tasks, the central nervous system action potentials and global synkinesis level were compared. The central nerve action potentials were measured with H/Mmax ratio and V/Mmax ratio. To obtain global synkinesis level, surface electromyography data were digitized, processed to root mean square. In our study, The global synkinesis level during knee flexion and extension was decreased in the mental arithmetic and in the post-handgrip ischemia task(p<.05) but not in the grip task. Also, V/Mmax ratio was decreased all in the three task(p<.05). In conclusion, we know that the central nervous system excitability and the muscle tone in chronic hemiplegic patients were decreased by the increased sympathetic outflow.

• Journal of Korean Academy of Nursing
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• v.29 no.2
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• pp.328-335
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• 1999

This study was designed to investigate the effects of exercise therapy on joint mobility, daily activity. pain and depression of patients with ankylosing spondylitis. 25 persons with the experimental group and 25 persons with the control group were conveniently sampled among out-patients diagnosed with ankylosing spondylitis at the rheumatism center of H University Medical Center. The control patients were matched to the experimental group and they were selected considering sex and age. The exercise therapy was developed by the author with the assistance of exercise specialists. The program includes muscle relaxation, flexibility, muscle strengths, breathing strengths and straight posture exercises. The 20-minute exercise therapy was carried out to the experimental group once a day for eight weeks from October. 1997 to February, 1998. Before and after the experiments, joint mobility, daily activity, pain and depression were measured respectively. Data were analyzed by $\chi$$^2$-test. t-test, paired t-test and unpaired t-test. The results were as follows : Joint mobility(cervical flexion, extension, shoulder flexion, abduction, hip abduction, knee flexion and fingertip to floor distance) and daily activity in the experimental group after the exercise were significantly increased than that in the control group. The pain and depression score in the experimental group after the exercise were significantly decreased than that in the control group. These findings may indicate that the exercise therapy is effective in increasing the joint mobility and daily activity, and also effective in decreasing pain and depression in patients with ankylosing spondylitis, Accordingly, the exercise therapy can be adopted as an effective nursing intervention for ankylosing spondylitis.

• Korean Journal of Acupuncture
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• v.28 no.3
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• pp.13-23
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• 2011

Objectives : The aim of this study was to develop the combined medical stimulus system consisted of the PEMFs (Pulsed electromagnetic fields) and LED which are able to stimulate local point such as acupoints and trigger points. Methods : To evaluate the therapeutic effect on the musculoskeletal disorders and the possibility of alternative method on manual acupuncture, we compared the fatigue recovery of two groups by analyzing the EMG and peak torque (non-stimulation and, stimulation group) after strenuous knee exercise. We chose the LR9 as a stimulation point. Results : The median frequency (MF) and fatigue index (F.I) of the stimulation group were recovered faster than those of the non-stimulation group. Also the peak torques of both groups were not restored until after 20 minutes. However, the peak torque of the stimulation group was regained higher than that of the non-stimulation group. Conclusions : We confirmed that the proposed combined stimulus system had useful effects as treatment instrument of musculoskeletal disorder using non-invasive method of PEMFs and LED.

• Journal of the Korean Society of Clothing and Textiles
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• v.41 no.1
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• pp.184-195
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• 2017

Baseball is a life sport that gives vitality to people. However, currently available leg guards do not have a variety of sizes and it is very difficult to purchase a leg guard that is suitable for the size of a specific consumer. Therefore, this study investigated the size system of a leg guard sold in the market and suggested a grading deviation suitable for the legs of Korean males. The results of the study were as follows. First, most brands were sold only in three size systems as children's, teenagers, and adults. Adult size systems were not subdivided. Second, Korean male legs were classified into Group 1 (large girth and height and lower body muscle) and Group 2 (small girth and height and low underbody muscle). Third, the size system is based on vertical items such as height and mid-thigh circumference. Each group produced 10 sizes. The smallest height or the largest height was also found to be about 4.5 to 5.0cm smaller or larger than the sample size for each group. The total length of the leg guard was about 2.5cm when the height was increased or decreased by one size. It was confirmed that the deviation of the circumference of the mid-thigh should be about 2.0cm larger or smaller than the sample size even if the height is the same. The deviation of the knee circumference and ankle circumference was smaller than the other circumference. In conclusion, the dimension combinations of the leg guard must be set differently to provide a leg guard with high size suitability according to leg type.

• The Journal of the Korea Contents Association
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• v.18 no.8
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• pp.338-344
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• 2018

The purpose of this study was to determine the optimal number of excitations(NEX) of diffusion weighted imaging(DWI) which is clinically useful in patients with musculoskeletal diseases while the scan time is relatively long. In this study, 30 patients underwent knee MRI using diffusion weighted image sequence using b values targeted on the bone and muscle. The NEX were varied from 1 to 5 and the ADC values were measured and analyzed. As a result of the study, 4 NEX and 2 NEX showed an statistically identical effect with the existing NEX on the bone and muscle diffusion weighted images, respectively. Also, it proved that the scan time could be significantly reduced by 21.2 % and 59.6 % compared to the established NEX which meant the optimal NEX could replace the existing NEX. In conclusion, applying the optimal NEX on the musculoskeletal bone and soft tissue DWI could improve the problems caused by the long scan time.