• Korean Journal of Applied Biomechanics
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• v.25 no.3
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• pp.275-281
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• 2015

Objective : In order for Taekwondo athletes to perform destructive kicking performance, they are expected to have Taekwondo-specific muscle properties such as high muscle strength and power. The purpose of this study was to investigate the joint angle-dependent force-producing property of Taekwondo athletes' knee extensor muscles, which is one of the primary muscle groups involved in kicking performance. Method : Ten Taekwondo male athletes (age: $19.9{\pm}0.7yrs$, height: $180.6{\pm}6.2cm$, body mass: $75.9{\pm}8.9kg$, career: $9.2{\pm}2.9yrs$.) and 10 healthy male non-athletes (age: $26.3{\pm}2.6yrs$, height: $174.2{\pm}4.8cm$, body mass: $72.8{\pm}7.7kg$) participated in this study. Subjects performed maximum isometric knee extension at knee joint angles of $40^{\circ}$, $60^{\circ}$, $80^{\circ}$, and $100^{\circ}$ (the full knee extension was set to $0^{\circ}$) with the hip joint angles of $0^{\circ}$ and $80^{\circ}$ (the full extension was set to $0^{\circ}$). During the contractions, knee extension torque using an isokinetic dynamometer simultaneously with muscle activities of the rectus femoris (RF), and the vastus lateralis (VL) and vastus medialis (VM) using surface electromyography were recorded. Based on the torque values at systematically different knee-hip joint angles, the joint torque-angle relationships were established and then the optimal joint angle for the knee extensor was estimated. Results : The results of this study showed that the isometric knee extension torque values were greater for the Taekwondo athletes compared with the non-athlete group at all hip-knee joint angle combinations (p<.05). When the hip joint was set at $80^{\circ}$, the peak isometric torque was greater for the Taekwondo athletes compared with the non-athlete group ($313.61{\pm}36.79Nm$ and $221.43{\pm}35.92Nm$, respectively; p<.05) but the estimated optimum knee joint angles were similar ($62.33{\pm}5.71^{\circ}$ and $62.30{\pm}4.67^{\circ}$ for the Taekwondo athletes and non-athlete group, respectively). When the hip joint was set at $0^{\circ}$, the peak isometric torque was greater for the Taekwondo athletes compared with the non-athlete group ($296.29{\pm}45.13Nm$ and $199.58{\pm}25.23Nm$, respectively; p<.05) and the estimated optimum knee joint angle was larger for the Taekwondo athletes compared with the non-athlete group ($78.47{\pm}5.14^{\circ}$ and $67.54{\pm}5.77^{\circ}$, respectively; p<.05). Conclusion : The results of this study suggests that, compared with non-athletes, Taekwondo athletes have stronger knee extensor strength at all hip-knee joint angle combinations as well as longer optimum muscle length, which might be optimized for the event-specific required performance through prolonged training period.

• Journal of Life Science
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• v.16 no.6
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• pp.890-897
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• 2006

The purpose of this study is to investigate the effects of BCAA and additional OKG or albumin supplementation on energy metabolism and hormone changes in prolonged submaximal exercise. The subjects of this study were 5 male college students, and they took participated in each experiment. In each experiment (control, BCAA, BCAA+OKG, BCAA+albumin), the subject ran for 90 minutes on the treadmill. Blood was drawn and analyzed as glucose, FFA, ammonia, growth hormone, insulin, cortisol, $T_3$, and $T_4$. The obtained results were analyzed via two-way repeated ANOVA using SPSS program. A value of p<.05 was considered statistically significant. The concentration of glucose was the lowest in the BCAA supplement group, and there was significant difference between times of exercise (p<.05). In concentration of FFA, there was a significant difference between times of exercise and supplemented groups (p<.05). The concentration of blood ammonia was the lowest in the BCAA+albumin supplement group, and was the highest in the BCAA supplement group. Concentration of growth hormone, cortisol, $T_3$ and $T_4$ were increased as exercise progressed and decreased after all exercise. But concentration of insulin was decreased as exercise progressed. In these results, BCAA and additional OKG or albumin supplement with BCAA may make better effect to the increasing energy generation and inhibiting protein degradation during prolonged submaximal exercise.

• Journal of the Korea Convergence Society
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• v.13 no.3
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• pp.327-335
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• 2022

This study aimed to compare functional recovery after rehabilitation exercise between isolated PCL reconstruction and combined PLC reconstruction. Patients were divided into two groups: those who had isolated PCL reconstruction (n = 16) and those who had combined PLC reconstruction (n = 16). We assessed knee joint ligament laxity, subjective questionnaires, and isokinetic muscle function before, after 12, and 24 weeks of a rehabilitation exercise program. In both groups, there were significant differences in knee joint laxity (p = 0.048), IKDC subject score (p < 0.001), Lysholm knee (p < 0.001), Tegner activity scale (p = 0.027), and isokinetic muscle deficit (p = 0.040) by estimated period. However, no significant difference between groups was observed (p > 0.05). These results suggest that rehabilitation exercise after isolated PCL and combined PLC reconstruction influenced structural, subjective, functional recovery positively.

• Journal of Navigation and Port Research
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• v.32 no.1
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• pp.109-114
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• 2008

This study is about the status and comparison of recreational scuba diving certification system in Southeast Asia countries. For the collection of the information, the contents of the numerous corresponding Internet sites were utilized, related documents were surveyed. And to supplement the information extensive interviews were held with the representatives of tourism department of many countries as well as staffs of diving associations, resort operators and diving instructors during various 2007 Dive Expos held in Southeast countries. In this paper, the relation between scuba certification and international standards were introduced for better understanding of the certification system. The research result shows that the scuba diving industry plays an important role in their country's tourism and the certification market of the Southeast Asia has grown to be greater than 30% of the world total market. However due to the facts that the scuba activity is originated from the western world and the controlling headquarters of the most certification agency are also located there, Southeast countries cannot take any leading roles in the scuba diving policies and systematic issues. Accordingly any modifications or improvements are expected to be very difficult. Also while Europeans and Americans have launched the programs and organizations for the quality assurance by cooperating with the international standards, but no such activity has yet appeared on the surface in Southeast Asia. According to the investigation the necessity will become bigger in near future.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.12
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• pp.4945-4953
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• 2010

The purpose of this study was to analyze the differences in perception levels of goals and concepts of physical education by the body image and gender of middle school students. Among 461 middle students randomly selected by a multistaged cluster sampling technique, 433 students(boys 267, girls 166) filled out questionnaires consisted of Figure Rating Scale and modified ones. To know the differences in the perception levels of goal and concept of physical education by sex, t-test was utilized. In order to find out the differences in the perception levels of goal and concept of physical education by body image, ANOVA was performed using the SPSS Windows 12.0. The results of this study revealed that boys had higher level of goal and concept of physical education than girls. Second, middle school students classified into normal body image was higher level of goal and concept of physical education that other body images such as very thin, thin, very obese, and obese ones. The results of this study indicated that curriculum of physical education focused on fragmentation of health, psychomotor, cognitive, affective, leisure, holistic human should make girls understand thoroughly and deeply goals and concepts of physical education and ideal body image.

• The Korean Journal of Physiology and Pharmacology
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• v.16 no.3
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• pp.175-180
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• 2012

Yoga has been known to have stimulatory or inhibitory effects on the metabolic parameters and to be uncomplicated therapy for obesity. The purpose of the present study was to test the effect of an 8-week of yoga-asana training on body composition, lipid profile, and insulin resistance (IR) in obese adolescent boys. Twenty volunteers with body mass index (BMI) greater than the 95th percentile were randomly assigned to yoga (age $14.7{\pm}0.5$ years, n=10) and control groups (age $14.6{\pm}1.0$ years, n=10). The yoga group performed exercises three times per week at 40~60% of heart-rate reserve (HRR) for 8 weeks. IR was determined with the homeostasis model assessment of insulin resistance (HOMA-IR). After yoga training, body weight, BMI, fat mass (FM), and body fat % (BF %) were significantly decreased, and fat-free mass and basal metabolic rate were significantly increased than baseline values. FM and BF % were significantly improved in the yoga group compared with the control group (p<0.05). Total cholesterol (TC) was significantly decreased in the yoga group (p<0.01). HDL-cholesterol was decreased in both groups (p<0.05). No significant changes were observed between or within groups for triglycerides, LDL-cholesterol, glucose, insulin, and HOMA-IR. Our findings show that an 8-week of yoga training improves body composition and TC levels in obese adolescent boys, suggesting that yoga training may be effective in controlling some metabolic syndrome factors in obese adolescent boys.

• Fire Science and Engineering
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• v.34 no.2
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• pp.97-102
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• 2020

The purpose of this study was to investigate the effectiveness of a Tabata exercise program as an alternative for firefighters whose working environment makes it difficult to manage physical fitness. The Tabata exercise program, in which 16 people participated, led to increased muscle mass and reduced weight and body fat, which not only improved the health of the firefighters but also improved their cardiopulmonary endurance, muscle endurance, and muscle strength, which are essential elements during firefighting emergency relief activities. On the basis of these results, it is believed that developing and providing guidelines for scientific and systematic exercise programs to firefighters will lead to better work capability during fire and disaster situations.

• Health Policy and Management
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• v.27 no.2
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• pp.149-156
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• 2017

Background: This study was conducted to evaluate the performance of the Hierarchical Condition Category (HCC) model, identify potentially high-cost patients, and examine the effects of adding prior utilization to the risk model using Korean claims data. Methods: We incorporated 2 years of data from the National Health Insurance Services-National Sample Cohort. Five risk models were used to predict health expenditures: model 1 (age/sex groups), model 2 (the Center for Medicare and Medicaid Services-HCC with age/sex groups), model 3 (selected 54 HCCs with age/sex groups), model 4 (bed-days of care plus model 3), and model 5 (medication-days plus model 3). We evaluated model performance using $R^2$ at individual level, predictive positive value (PPV) of the top 5% of high-cost patients, and predictive ratio (PR) within subgroups. Results: The suitability of the model, including prior use, bed-days, and medication-days, was better than other models. $R^2$ values were 8%, 39%, 37%, 43%, and 57% with model 1, 2, 3, 4, and 5, respectively. After being removed the extreme values, the corresponding $R^2$ values were slightly improved in all models. PPVs were 16.4%, 25.2%, 25.1%, 33.8%, and 53.8%. Total expenditure was underpredicted for the highest expenditure group and overpredicted for the four other groups. PR had a tendency to decrease from younger group to older group in both female and male. Conclusion: The risk adjustment models are important in plan payment, reimbursement, profiling, and research. Combined prior use and diagnostic data are more powerful to predict health costs and to identify high-cost patients.

• Journal of the Korean Society of Physical Medicine
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• v.4 no.3
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• pp.141-148
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• 2009

Purpose：The purpose of this study was analyze the effect combination exercise program on plasma total antioxidant capacity and free oxygen radical according to exercise frequency of elderly. Age range of subject is 65~70 years. Methods：Subjects divided into three groups: control group(0-time), week-3 times group(3-times), week-5 times group(5-times). Each group were performed combination exercise during 8 weeks. Results：The results of each group by ANOVA free oxygen radical have a change(p<.05). We performed comparison of total antioxidant capacity and free oxygen radical pre-test and post-test on each groups. Total antioxidant capacity was increased in the 3-times and 5-times groups but there have not significant. Total antioxidant capacity is improve better than to 5-times. Free oxygen radical is significant increased in the 0-time (p<.05). But 5-times but 3-times is no significant decrease. Free oxygen radical is improve better than to 3-times. Conclusion：In the old people, exercise frequency week 3 times doing appeared effectively in improvement of the free oxygen radical and 5 times doing appeared effectively in improvement of the total antioxidant capacity. So rightly must apply a exercise frequency well in characteristic of old person each person.

• Journal of the Korea Convergence Society
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• v.11 no.6
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• pp.383-391
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• 2020

The purpose of this study was to identify the moderating effect of self-control in the relationship between online game addiction and depression among adolescents exposed to the online game environment. A total of 378 respondents who are high school students in K Metropolitan City were selected for the current study. The process macro program developed by Andrew F. Hayes was used to analyze for the moderating effect and the SPSS 25.0 program was used for frequency, descriptive statistics, and correlation analysis. The results showed that online game addiction in adolescents had a significant positive effect on depression and self-control had a negative effect on depression, and self-control had a moderating effect on the relationship between online game addiction and depression in adolescents. The higher the online game addiction among adolescents, the higher the depression, and the influence depends on the level of self-control.