• Korean Journal of Applied Biomechanics
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• v.28 no.4
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• pp.199-205
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• 2018

Objective: The purpose of this study was to examine the effect of increase in barbell weight on closely related variable to the anterior cruciate ligament (ACL) injury which are knee joint kinematics, joint load, joint moment, and maximum load attainment point during snatch of the weight lifting. Method: The subjects of the study were 10 male Korean national weight lifting athletes (69 kg 5, 77 kg 5; age: $21.80{\pm}3.91yrs.$, height: $168.00{\pm}4.06cm$, weight: $75.00{\pm}4.02kg$, career: $7.8{\pm}3.99yrs.$, snatch records: $168{\pm}4.06kg$). The weight of the barbell during the snatch operation was set at 70%, 75% and 80% of the highest records for each subject studied. Results: The result obtained from the one-way repeated measure ANOVA are as follows: With increased barbell weight, the extension moment of the left knee joint was higher in the 80% condition than the 70% (p<.001). However, other variables were not statistically significant difference. According to the factor analysis of the variables related to maximum load attainment point of the ACL major injury variables, the first sub-factor was the internal shear force, the posterior shear force, the abduction moment, and the muscle activity of the VL. The second sub-factor was the extension moment of the knee joint, compressive force, adduction moment, and the third sub-factor was the muscle activity of BF. Conclusion: These results indicate that the possibility of ACL injury can be lowered when performing a stable snatch movement.

• Korean Journal of Applied Biomechanics
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• v.30 no.1
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• pp.37-49
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• 2020

Objective: The purpose of this study was to investigate the injury factors of Taekwondo jumping kick during landing phase according to the experience of injury and to suggest a stable landing movement applicable to free style Poomsae. Method: The participants were non-injury group (NG), n = 5, age: 20.5±0.9 years; height: 171.6±3.6 cm; body weight: 65.7±4.4 kg; career: 5.0±2.7 years. Injury group (IG), n = 9, age: 21.0±0.8 years; height: 170.9±4.6 cm; body weight: 67.1±7.0 kg; career: 8.6±5.0 years. The variables are impact force, loading rate, vertical stiffness, lower limb joint angle, stability, balance, and muscle activity in the landing phase. Results: NG was statistically larger than IG in the gluteus medius (p<.05). The impact force, loading rate and vertical stiffness decreased as the landing foot angle, the ROM of lower limb joint angle and COM displacement increased (p<.05). Conclusion: Based on the results, it means that the landing foot angle plays an important role in the impact reduction during landing phase. It is required the training to adjust the landing foot angle.

• Journal of Sport and Applied Science
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• v.3 no.2
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• pp.11-16
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• 2019

Purpose: New sports is a modified physical activity which is developed for participants to easily learn and play. This study is to analyze distribution channels and related strategies of Korea new sports and to discuss strategies for promoting Korea new sports, especially for two-two ball. Research design, data, and methodology: The study reviewed literatures including documents of Dae-Han two-two-ball association and new sports related research articles. Results: First, Dae-Han two-two-ball association has introduced two two ball to consumers via educational organizations such as schools and youth education sectors. Second, Dae-Han two-two-ball association has introducted two two ball to school teachers by teacher training sessions. Third, Dae-Han two-two-ball association has educated future instructors and provided certificates to them. Fourth, Dae-Han two two ball association has applied governmental projects and sought to promote domestic new sports. Finally, Dae-Han two two ball association has hosted national events every year for facilitating Korea new sports across nation. Conclusions: In conclusion, Korea new sports shoud be spread out by school teachers and educational organizations. Two-two ball association needs to develop a systematic educational and managerial process for training instructors. Finally, Two-two ball association needs to make opportunities of teacher training sessions. Future directions were discussed.

• Korean Journal of Applied Biomechanics
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• v.32 no.3
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• pp.80-86
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• 2022

Objective: The purpose of this study was to investigate the effects of three rotational jump conditions (standing jump, left rotational jump and right rotational jump) on stability through center of pressure (COP) and EMG variables analysis. Method: A total of 16 college students (age: 24.13 ± 7.17 years, height: 169.24 ± 8.23 cm, weight: 65.65 ± 13.88 kg) participated in this study. The study used wireless two COP plates and wireless eight channel EMG. The analyized variables were 11 variables for COP and RMS for EMG, which were analyzed using one-way analysis of variance with repeated measures according to three rotational jump conditions. Results: Among the COP variables, left rotational jump (LRJ) and right rotational jump (RRJ) were larger than standing jump (SJ) for left and right amplitude, area, total displacement, and average velocity for both feet among the variables of COP, and for area of the left foot, RRJ was larger than that of SJ. Among the EMG variables, there was no statistical difference between the muscle activations, but the muscle activity was significantly higher in the order of RRJ, LRJ, and SJ according to direction of rotation. Conclusion: Although the results of COP and EMG were not consistent through this study, it can be expected that the differences in COP was due to the amount of rotation during rotational jump-landing in the left and right directions, and that the EMG is determined by the lateral movements required for rotation.

• Korean Journal of Applied Biomechanics
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• v.17 no.2
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• pp.197-205
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• 2007

The purpose of this study is to analyze the muscle activations and Ground Reaction Force(GRF) in university judo players, and provide the guide of training in Judo. Using surface electrode electromyography(EMG), we evaluated muscle activity in 5 university judo players during the Judo Uke Movements. Surface electrodes were used to record the level of muscle activity in the Tibialis Anterior, Rectus Femoris, Elector Spinae, Gluteus Maximus, Gastrocnemius muscles during the Uke. These signals were compared with %RVC(Reference voluntary contraction) which was normalized by IEMG(Integrated EMG). The Uke was divided into four phases : Kuzushi-1, Kuzushi-2, Tsukuri, Kake. The results can be summarized as follows: 1. The effective Uke Movements needs to short time in the Kake Phase 2. The Analysis of Electromyography of Uke Movements in Supporting Leg; TA(Tibialis anterior) had Higher %RVC in the Kuzushi Phase, RF(Rectus Femoris) had Higher %RVC in the Tsukuri Phase, GM(Gluteus Maximus) had Higher %RVC in the Kake Phase 3. The ground reaction force for Z(vertical) direction was showed increase tendency in Kuzushi phase, Tsukuri phase and decrease tendency in Kake phase.

• Korean Journal of Applied Biomechanics
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• v.22 no.2
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• pp.253-259
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• 2012

The purpose of this study was to determine how smartphone use posture affects biomechanical variables and muscle activities. Eleven university students(age: $22.2{\pm}2.6$ yrs, height: $176.6{\pm}4.7$ cm, weight: $69.5{\pm}7.5$ kg) who have no musculoskeletal disorder were recruited as the subject according to having experience in using the smartphone for more than one year. Angular velocity, muscle activity, and thumb finger pressure were determined for each trial. For each dependent variable, a one-way analysis of variance (ANOVA) with repeated measures was performed to test if significant difference existed among different three conditions (p<.05). The result showed that rotational angular velocity of the first metacarpal were increased in DESK posture compared with STAND posture during SU phase. The average nEMG values of FDI(First dorsal interosseous) were less in SIT and DESK posture compared with STAND posture during SR phase. These indicated that smartphone postures may effect the thumb ROM(Range of motion) and muscle activity. This has led to suggestions of the need for further kinetic and EMG analyses to evaluate best assess and characterize with smartphone use.

• The Korean Journal of Physiology and Pharmacology
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• v.15 no.1
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• pp.37-41
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• 2011

Interstitial cells of Cajal (ICC) evoke pacemaker activities in many tissues. The purpose of this study was to investigate the relationship between interstitial cell and pacemaker activity in the human ureter through the recording of spontaneous contractions. Spontaneous contractions of eight circular and longitudinal smooth muscle strips of the human ureter to acetylcholine (ACh) and/or norepinephrine (NE) were observed. Human ureteral strips were divided into proximal and distal groups, and each group was subdivided into circular and longitudinal groups. The proximal group showed spontaneous activities of 3~4 times within 5 minutes in the longitudinal group. ACh ($10^{-4}\;M$) augmented the frequency of the spontaneous contractions. The cumulative application of NE also augmented the frequency in a dose-dependent manner. The effects of NE application were inhibited by concomitant application of $10^{-5}\;M$ glibenclamide. Receptor tyrosine kinase (c-kit) staining revealed abundant ICCs only in proximal tissues. Therefore, spontaneous contractions of the human ureter might be modulated by ICC in the proximal region, and the actions might be related with the activation of cholinergic and/or adrenergic system mediated by a glibenclamide-sensitive pathway.

• Korean Journal of Applied Biomechanics
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• v.14 no.2
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• pp.167-178
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• 2004

The purpose of this study was to describe and compare the selected electromyographical muscle activities of trunk and hip during Professional and Amateur golfer's Iron swing. Using surface electromyography, we evaluated muscle activities in 6 male professional golfers and 6 male amateur golfers during the golf iron swing. Surface electrodes were used to record the level of muscle activity in the right abdominal oblique, left abdominal oblique, right erector spinae, left erector spinae, right rectus abdominis, left rectus abdominis, right gluteus maximus, left gluteus maximus muscles during the golfer's swing. These signals were compared with IEMG(Integrated EMG) which was normalized by %RVC(Reference voluntary contraction). The golf swing was divided into three phases: take away, forward swing-acceleration, follow-through. We observed patterns of trunk muscle activity throughout three phases of the golf swing. The results can be summarized as follows: LES(Left Erector spinae) had statistically significant difference in take away and forward swing-acceleration phases. It was showed no significant difference in follow-through phase.

• Korean Journal of Applied Biomechanics
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• v.13 no.1
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• pp.121-137
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• 2003

The purpose of this study was to investigate the effect of the stair heights on lower extremity joint moment in stair-ascent activity Data were collected by 3-D cinematography, force platform. six normal males were participated in this experiment. All subjects performed a stair-ascent in four different heights of stairs (10, 14, 18, 22cm) having a 5 step staircase. The moment of lower extremity joint was analyzed during stance phase. The results were as follows: First, the second increase of plantar flexion moment of ankle joint in the 'forward continuance' phase was not occurred for stair A and B. But it occurred for stair C and D. And the maximum plantar flexion moment increased as the stair height become higher. Second, it was shown that the maximum inversion moment of the ankle joint was the smallest at stair B and it increased significantly at stair C. Third, maximum extension moment appeared in the 'pull-up' phase. And it increased as the stair height become higher. Fourth, it was shown that the maximum abduction moment of the knee joint was the smallest at stair C and it increased significantly at stair C. Fifth, maximum extension moment of hip joint increased significantly at stair C. Sixth, remarkable value of adduction moment occurred at hip joints and maximum adduction moment increased at stair D.

• Fashion & Textile Research Journal
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• v.21 no.1
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• pp.46-58
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• 2019

This study analyzes the effects of lifestyle on wetsuits purchasing behavior and identifies various characteristics among lifestyle groups. A questionnaire survey of 213 domestic consumers with water sport activity and wetsuits experience indicated the following results: 1) Lifestyle factors were analyzed as 6 factors: social relation ships, development orientation, trend & appearance, domestic, positive acknowledgement of hobbies, pursuit of practicality. And the wetsuits selection criteria was 4 factors: wearing fitness, product information, design, reputation. 2) Social relationships, development orientation, positive acknowledgement of hobbies and pursuit of practicality factors had a positive effect fitness. Trend & appearance, development orientation, and pursuit of practicality factors had a positive effect on product information factors ; in addition, development orientation, and trend & appearance, a positive acknowledgement of hobbies factors had a positive effect design factors. Social relationships, trend & appearance, and pursuit of practicality factors had a positive effect on reputation factors. However, trend & appearance factors negatively affected the wearing fitness factors and the positive acknowledgement of hobbies factors had negative effect on product information, reputation factors. 3) The three groups of lifestyle factors showed differences in monthly average purchasing of clothes, average annual purchasing expenditures for water sports related products, number of water sport activity days and frequency, product selection criteria.