• Journal of the Korean Applied Science and Technology
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• v.34 no.4
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• pp.827-838
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• 2017

Twenty male soccer players volunteered as the experimental subjects. The subjects were randomly assigned to the "Winter training with Cornus officinalis extract intake group"(WCI; n=10) and "Winter training group"(WT; n=10). The variables of blood fatigue substance, muscle damage and liver function where measured in all the subjects before the start of the Cornus officinalis intake after at the end of the 4 weeks winter training. Winter training program was proceeded with 6 days a week for 4 weeks. Exercise intensity was measured using the HRR(70~95%). Changes in the heart rate were also measured with the Polar. WCI group were ingested 80 mL of Cornus officinalis extract after every breakfast and dinner for 4 weeks. The test data were analyzed by paired t-test, and independent t-test(%diff), and the alpha level of p<.05 was set for all tests of significance. Lactate in WCI group had significantly decreased, and the changes between the groups were significantly lower in the WCI group than in the WT group. Ammonia in WCI group had significantly increased. CK in WCI group had significantly decreased. LDH in both group had significantly decreased. AST in WCI group had significantly decreased, and the changes between the groups were significantly lower in the WCI group than in the WT group. ALT in WCI group had significantly decreased. In conclusion, the results of this study show that Cornus officinalis extract seem to have a positive influence on blood fatigue substance, muscle damage and liver function. Therefore Cornus officinalis extract is considered to be able to contribute an ergogenic aids.

• Tuberculosis and Respiratory Diseases
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• v.44 no.3
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• pp.583-591
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• 1997

The functional derangement of skeletal muscles which may be attributed to chronic hypoxia has been accepted as a possible mechanism of exercise impairment in patients with chronic obstructive pulmonary disease (COPD). The metabolic changes in skeletal muscle in patients with COPD are characterized by impaired oxidative phosphorylation, early activation of anaerobic glycolysis and excessive lactate and hydrogen ion production with exercise. But the cause of exercise limitation in patients with chronic lung disease without hypoxia has not been known. In order to evaluate the change in the skeletal muscle metabolism as a possible cause of the exercise limitation in chronic lung disease patients without hypoxia, we compared the muscular metabolic data of seven male patients which had been derived from noninvasive $^{31}P$ magnetic resonance spectroscopy(MRS) with those of five age-matched normal male control persons. $^{31}P$ MRS was studied during the sustained isometric contraction of the dominant forearm flexor muscles up to the exhaustion state and the recovery period. Maximal voluntary contraction(MVC) force of the muscle was measured before the isometric exercise, and the 30% of MVC force was constantly loaded to each patient during the isometric exercise. There were no differences of intracellular pH (pHi) and inorganic phosphate/phosphocreatine(Pi/PCr) at baseline, exhaustion state and recovery period between two groups. But pHi during the exercise was lower in patients group than the control group (p < 0.05). Pi/PCr during the exercise did not show significant difference between two groups. These results suggest that the exercise limitation in chronic lung disease patients without hypoxia also could be attributed to the abnormalities in the skeletal muscle metabolism.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.10
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• pp.4917-4926
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• 2012

This study was designed to assess the factor of influence to occupational stress who work in the field of firefighters and questionnaire was uesd to analyse the stress scores and find the primary factors influence to occupational stress. The number of respondents were 408 who received the refresher training and period of investigation was august 2011 through october 2011. A structured questionnaire was employed to evaluate the participants' socio-demographics, job-related factors, health-related behaviors, occupational stress, reaction factor (fatigue, job satisfaction) and buffer factor (social support). Occupational stress and fatigue were assessed using the Korean Occupational Stress Scale-Short Form (KOSS-SF) and the Multidimensional Fatigue Scale (MFS), respectively. The analysis showed that we found a strong correlation between fatigue, job satisfaction and occupational stress. Occupational stress was associated with an increased risk of fatigue and decreased the job satisfaction. In the multiple regression analysis(stepwise), main factor that influence to occupational stress were job satisfaction, gender, age, processing number for a day, exercise. In logistic regression analyses, a higher occupational stress was associated with higher odds of fatigue(High) and the odds was down by 15.0% after adjustment for job satisfaction, gender, age, processing number for a day, exercise. Thus, a job satisfaction promote program for the reduction of occupational stress and the promotion of firefighters's health is strongly recommended.

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.3
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• pp.363-369
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• 2014

Purpose: Three-dimensional (3D) displays are very useful in many fields, but induce physical discomforts in some people. This study is to assess symptom type and severity of asthenopia with their habitual distance corrective spectacle (HDCS) and their binocular vision corrective spectacle lenses (BVCSL) in people who feel physical discomforts. Methods: 35 adult subjects (ages $32.2{\pm}4.4$ yrs) were pre-screened out of 98 individuals to have the highest symptom/asthenopia scores following 65 minutes of 3D television viewing with HDCS. These 35 individuals were then retested symptom/asthenopia scores during they watched 3D television for 65 minutes at a distance of 2.7 m with wearing BVCSL of horizontal, vertical or base down yoked prisms. A 4-point symptom-rating scale questionnaire (0=no symptom and 3=severe) was used to assess 11 symptoms (e.g., blur, diplopia, etc.) related to visual fatigue/visual discomfort. Distance and near lateral phoria were measured using Howell phoria card and vertical phoria were measured using Maddox rod. Symptoms induced by watching 3D TV were compared between wearing HDCS and BVCSL. Results: Asthenopia in watching 3D TV with wearing BVCS was significantly lower than wearing HDCS at 5, 25, 45, and 65 minutes (all p < 0.001, paired t-tests). In only refractive error power correction power group, all asthenopia was not significantly different between HDCS and BVCSL (all $p{\geq}0.05$, paired t-tests). In prism correction groups for binocular imbalance, symptoms of asthenopia, however, was significantly lower for when wearing BVCSL than when wearing HDCS (all p < 0.05). Conclusions: Correction of phoria/vergence-based binocular vision imbalance can reduce asthenopia during 3D television viewing. An individual with binocular vision imbalance need corrected/compensated glasses with appropriate prisms prior to prolonged viewing of 3D television displays to reduce asthenopia/visual fatigue.

• Journal of Life Science
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• v.25 no.11
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• pp.1324-1330
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• 2015

The present study was performed to analyze and review the physical and immune responses to overtraining syndrome in humans. Overreaching refers to the initial phage of overtraining syndrome and has been known as a physical fatigue which is mainly from metabolic imbalance. It has been known that overtraining also results in a loss of adaptability which may lead to an attenuation of exercise performance, sleeping disorder, central fatigue, neurohormonal changes, difficulty recovery to physical stress, and immunological changes. Additionally, overtraining syndrome is characterized by persistent fatigue, poor performance in sport due to the prolonged and strenuous physical training. Also, previous studies reported that endurance athletes experienced a high incidence of URTI during intense training and the post training. And also, high-performance athletes reported that suppression of cell mediated and anti-body mediated immune function. NK cell numbers were also reduced in the period of overtraining syndrome. Major components of prevention and treatment for the overtraining syndrome are screening, education, and detraining. Furthermore, the combination of these prevention and treatment strategies will be much helpful. Therefore, the current review will be helpful for athletes and individuals who are at the risk of overtraining syndrome.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.1
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• pp.42-48
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• 2014

Seasickness not only makes persons on board vessels to vomit but also causes vertigo, headache, sleepiness, fatigue, lethargy and other discomforts. This ailment leads to disturbance of biorhythm and decline of perception which would eventually cause reduction of situational awareness among ship's operators that leads to marine accident. This study is about the sensitivity of people onboard ships to seasickness and focused on deck or navigation officer cadets(apprentice officers) and engine officer cadets(apprentice engineers) who have no previous experiences on board. It is conducted by using motion sensor that can measure ship's X, Y, Z-axis motions and through the questionnaire survey, and evaluated each students' degree of seasickness symptoms. Through this study, in same circumstance, we have known that there are different degrees of motion sickness for wheel house worker and engine room worker, It also confirmed that seasickness have high relationship with degree of hull motion and also, with cycle of hull motion. In addition, we have confirmed that Z-axis hull movement has higher relationship with seasickness than X-axis and Y-axis hull movements. This study aims to initiate additional researches about X-axis and Y-axis of the ship's motion which it expects to greatly enhance safety of wheelhouse and engine room personnel, ship's livability and comfortable sailing.

• The Journal of Dong Guk Oriental Medicine
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• v.7 no.1
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• pp.99-117
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• 1998

Objective This experimental study was designed to investigate effects of Bo-joong-ik-gi-tang administration among long distance runners on changes of the energy and electrolyte metabolism. Materials and Methods All subjects were divided randomly with two groups, Bo-joong-ik-gi-tang Group (N=4) and control group (N=4) and performed to run the 400m track with 70% of HR max about 1 hour. The blood samples were collected from antecubital vein by 5ml syringes at before exercise, immediately after exercise, recovering-10 min. recovering-30 min, recovering-1 hour. These samples were used to analyze for the factors of the change on metabolic responses. First, the primary factors on the changes of the energy metabolism were checked ; Glucose, Free fatty acid, Lactate, LDH. Second, the primary factors on the changes of the electrolyte metabolism were checked ; Na+, CI-. K+. Results 1. The change of the energy metabolism 1) Glucose response was not shown significant difference between two groups. 2) Free fatty acid response in Bo-joong-ik-gi -tang group was significantly increased at recover-10 min. 3) Lactate response in Bo-joong-ik-gi-tang group was significantly decreased at immediately after exercise, recover-10 min, recover-30 min. 4) LDH response was not shown significant difference between two groups. 2. The change of the electrolyte metabolism 1) Na+ response in Bo-joong-ik-gi-tang group was shown significant difference between two groups at before exercise. 2) Cl- response in Bo-joong-ik-gi-tang group was significantly increased at before exercise, immediately after exercise. 3) K+ response in Bo-joong-ik-gi-tang group was significantly increased at recover-10 min. Conclusion According to the above results, it was shown that Bo-joong-ik-gi-tang had the positive effects on changes of the energy and electrolyte metabolism for the long distance runners.

• Journal of Life Science
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• v.25 no.7
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• pp.819-825
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• 2015

The use of fructose-containing sports beverage drinks has increased in recent years, especially at sport events, because of their reported ergogenic effects. However, the ingestion of low to moderate doses of caffeinated energy drinks has been associated with adverse side effects such as insomnia or increased nervousness. The purpose of this study was to investigate the effects of fructose beverage supplementation on cardiopulmonary function, blood lactate levels, and inflammatory reactions. We recruited 8 young adult subjects from D university and measured their cardiopulmonary functions before and after supplementation with sports beverage drinks. We also measured blood lactate and inflammatory reactions after a 20 min recovery period. Exercise time, maximal oxygen uptake (V0₂max), and AT HRmax were significantly increased (p<0.05) in the period of before and after sports beverage supplementation. However, no significant differences were observed in RPE, AT RER, V0₂max RER, AT V0₂max, and maximum heart rate (HRmax). Lactate levels also significantly decreased after 20 min recovery with sports beverage supplementation. Sports beverage supplementation therefore may enhance maximal V0₂max and increase the exercise duration time. These drinks may also be helpful in promoting rapid recovery of fatigue variables and increasing exercise performance time.

• Journal of Broadcast Engineering
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• v.17 no.1
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• pp.60-72
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• 2012

After the movie "AVATAR" became a good model of cash-cow in 3D movie, the profit of 3D-movie significantly reduced. One of the reasons why it happens comes from rare understanding of human factors for instance how viewers get immersed, but sometimes tired. Although 3D images should be more considered human visual system including eye, unfortunately most communication research ignored human factors. For those reasons this study observed the effect of 3D video on viewers' psychological response, especially for perceived eye movement, perceived characteristics, visual fatigue, and presence. With 90 participants, the results show that viewers' perceived feature effects on their presence. In detail, first, materiality and tangibility are more important factors than clarity in 3D video, and it means that when making 3D content or devices, materiality and tangibility should be considers that any other factor. Second, this study examined whether we perceive our eyes as media, and the result shows that as viewers' presence level became higher we perceive eye movements more, and as viewers' presence level became higher perceived visual fatigue became lower. This result means that when we move eyes, we interact with surrounded environment, so 3D content needs to provide vivid features to be more interactive. On the other hand, since level of presence increase visual fatigue, it must be balanced when producing and playing.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.11a
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• pp.33-39
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• 2004

A ship runs with various modes of motion due to waves. Among the modes, roll mainly influences on the safety of cargos and crew's fatigue. Therefore a ship equipped with anti-rolling devices are on an increasing trend. In this research, we developed a free running model ship to evaluate the performances of fin stabilizer and moving weight stabilizer. Also those performance tests were carried out through the proposed test procedure.