• Korean Journal of Exercise Nutrition
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• v.25 no.3
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• pp.8-15
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• 2021

[Purpose] Excessive reactive oxygen species (ROS) induced by prolonged high-intensity exercise can cause structural and functional damage. Antioxidant polyphenol supplementation, which reduces ROS levels, may improve high-intensity exercise performance. We evaluated the effect of lychee fruit extract, which contains high levels of low-molecular-weight oligomerized polyphenols, on high-intensity exercise performance. [Methods] Ten male athletes were included in an open-label trial that consisted of control and intervention phases, with a 7-day washout period between phases. The participants were administered oligomerized lychee fruit extract for seven days, whereas no intervention was given in the control phase. High-intensity intermittent exercise and the Wingate test were performed. The power output, blood lactate levels, reactive oxygen metabolite levels, biological antioxidant potential, heart rate, and rate of perceived exertion were measured. [Results] The average power output was significantly higher in the intervention phase than in the control phase (P < 0.01), while the change in blood lactate levels was significantly lower in the intervention phase than in the control phase (P < 0.05). The average heart rate was significantly higher in the intervention phase than in the control phase (P < 0.05), without changing the rate of perceived exertion. Although there was no difference in reactive oxygen metabolite levels between the phase, the change in biological antioxidant potential was larger in the intervention phase than in the control phase (P = 0.06). The Wingate test showed no significant differences between the phase. [Conclusion] Short-term loading with oligomerized lychee fruit extract may increase performance during high-intensity intermittent exercise by improving metabolism.

• Journal of the Ergonomics Society of Korea
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• v.15 no.2
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• pp.51-62
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• 1996

This research utilized the psychophysical methodology, where secrw drivers are used, to determine the effects of i) the location and orientation of work objects, and ii) wearing gloves, on ratings of perceived exertion at various body parts. The validity of the psychophysical methodology in determining a preferred work pace was also studied. The subjects drove screws with a screw driver into thick wooden sheet at three vertical and three horizontal locations. They drove serews for 3 minutes at each location and assessed the condition using the psychophysical scale. The results showed that only the vertical location was a significant factor in determining the discomfort ratings. Driving screws at elbow height on the vertical surface and with the lower arm close to the body on the horizontal surface were the work locations with the smallest ratings of perceived discomfort. Wearing gloves had significant effects on reducing the pain of the hand. From the experiment in which a comfortable work pace was identified using 20 minute psychophysical adjustment, it was found that the psychophysical method is sensitive to workers perception of the physical stress when the upper limbs are employed. This was confirmend by the high correlation between the psychophysical results and EMG measurement.

• Journal of Life Science
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• v.18 no.9
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• pp.1263-1270
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• 2008

The purpose of this study is to investigate the effect of exercise mode and anti-hypertensive drug responding status on the cardiovascular response and perceived exertion in acute coronary syndrome (ACS) patients. Seventy-five patients who participated in six-week exercise rehabilitation therapy performed a treadmill running and a cycle ergometer exercise at intensities of 60%HRR and 85%HRR respectively. Systolic and diastolic blood pressure, mean arterial blood pressure (MAP), rate pressure production (RPP), and ratings of perceived exertion (RPE) were measured. The results of cardiovascular response by the different exercise modes with moderate and intensive intensity of anti-hypertensive drug responder and nonresponder ACS patients were following: First cycle ergometer exercise induced significantly higher SBP, DBP, MAP, RPP and MAP than treadmill running exercise at the intensities of 60%HRR and 85%HRR in both anti-hypertensive responder and nonresponder ACS patients (p<0.05). Secondly anti-hypertensive nonresponder ACS patients had significantly higher DBP and MAP that anti-hypertensive responder ACS patients at all the exercise modes (p<0.05). Finally there was no difference of RPP between anti-hypertensive responder and nomresponder ACS patients, although anti-hypertensive nonresponder ACS patients showed higher blood pressure and RPP than anti-hypertensive responder ACS patients. In conclusion, cycle ergometer induced increased cardiovascular response at same intensities of treadmill running exercise and anti-hypertensive nonresponder ACS patients had even more increased cardiovascular response than anti-hypertensive responder ACS patients with no difference in perceived exertion during exercise. These results suggested that cycle ergometer exercise should be greatly careful with the risk of higher blood pressure, especially for those who are patients with hypertensive blood pressure.

• Design Convergence Study
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• v.14 no.5
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• pp.157-169
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• 2015

In this study, three axillary crutches(Mobilegs, KM crutch, Pro In-motion) were tested with 12 healthy male subjects by measuring the EMG activity of the latissimus dorsi and gastrocnemius and the user-perceived levels focusing on the comfort and ease of use. The result showed that the EMG activity of the gastrocnemius was significantly reduced during ambulation using Mobilegs and Pro In-motion compared with the ambulation using KM crutch, a conventional crutch. However, no statistically significant difference was found for EMG activity of the latissimus dorsi. Subjects perceived the Mobilegs to be more comfortable and easy to use than the other crutches. Theses result may delivered mostly from the characteristics of spring-loaded axillary pad and ergonomic crutch handle. The results indicate that ambulation using the spring-loaded crutch is much easy with asking less exertion at gastrocnemius. In addition, the characteristics of crutch design, such as embedded spring, makes muscles to consume less energy. When the reasonable structure and form of the axillary pad and crutch handle are applied herein, the ambulation using the crutches are perceived to comfort.

• Fire Science and Engineering
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• v.26 no.5
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• pp.8-12
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• 2012

The aim of study intends to investigate physical response of human body wearing Self Contained Breathing Apparatus and to provide the base data for the safety of firefighter. The results of the study are as follows. when wearing SCBA, the mean skin temperature (7 %), heart rate (28 %), rate of perceived exertion (65.4 %), metabolic equivalents (70.7 %) were significantly higher (p<.05), respiratory rate was not statistically significant. It is concluded that wearing SCBA causes significant stress to the physical systems.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.04a
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• pp.151-157
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• 1996

Postural tremor of the upper arm in a static posture was measured to provide guidelines of hand tool weight. Three types of camera recording postures were selected. Postural tremor was measured on five levels of tool weights; no weight, 400g, 800, 1200g, and 1600g. For each conditions, upper arm postural tremor was measured together with EMG of biceps, deltoid, and pectoralis major, and Borg's CR-20 scale ratings of perceived exertion. Results of the experiment are as follows; Frequency analysis of tremor revealed that increased amplitude of frequency band of 2-4Hz and 10-14Hz was observed. Postural tremor of the upper arm maintained the initial level until fatigue developed. After the development of fatigue, the rate of the change of postural tremor was significantly increased. Different tool weights and hand postures showed different rate of tremor increase. And time to fatigue and the corresponding endurance time was positively correlated with Borg's RPF scores.

• Journal of the Korean Society of Safety
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• v.13 no.1
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• pp.147-154
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• 1998

The objective of this study was to evaluate quantitatively the effects of handle types of garden tools on the ergonomic effectiveness, user satisfaction in terms of work performance, and subjective judgment of tactile feel and control. The approach was to compare garden tools with conventional wood handle and newly developed fiberglass handle, and to utilize three different tools: shovel, rake, and hoe. The hollow fiberglass handle was 12% more efficient than either the wood or solid fiberglass handle. The next important measure was the subjective ratings of the perceived exertion averaged across three different tools. The average ratings for the hollow fiberglass handle were the smallest. In conclusion, the hollow fiberglass handle showed better efficiency and better subjective acceptability for comfort, tactile feel, and especially decreased slipperiness.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.641-642
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• 2006

The purpose of this work is to investigate the effect of work load on heart rate variability (HRV) which is widely used marker of the autonomic nervous system activity. Average heart rate, rating of perceived exertion, and the power spectrum of heart rate variability were investigated in seven healthy males during exercise at various work loads. The subjects were divided into two groups according to the average heart rate during exercise, group 1 with lower heart rate and group 2 with higher heart rate. HF component showed decrease followed by increase with workload. Accordingly, the LF/HF ratio showed increase followed by decrease with workload. The peak in LF/HF ratio of group 1 was at the lower workload than that of group 2.

• Journal of the Korean Society of Clothing and Textiles
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• v.47 no.6
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• pp.1193-1203
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• 2023

This study aims to provide primary data regarding the thermal stress of disposable personal protective coveralls. Thermal stress and surface temperature measurements were taken among ten men wearing coveralls. The size of the ten men corresponds to a size eight in Size Korea. As a result of thermal stress, sensations of humidity and discomfort were higher when wearing Level C compared to Level D. Level D felt significant thermal stress in their upper body after exercise. However, they did not feel such stress in their lower body. Level C felt thermal stress in their upper and lower body after exercise. In addition, in Level C, the ratings of perceived exertion blood pressure and pulse rate after exercise were higher than those of Level D. Furthermore, the surface temperature of disposable personal protective coveralls among Level C was slightly higher than that of Level D.

• Journal of Korean Physical Therapy Science
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• v.13 no.3
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• pp.65-75
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• 2006

This study was to find out whether MBT shoes were more effective than general sporting shoes on the kinematic physiology. We comparatively analyzed energy consumption, heart rates, rating of perceived exertion, lactic acid density in blood and muscle activity with EMG. The subjects were 10 regular students of K Univ.(5 male and 5 female). They wore the general sporting shoes for stage 1(group 1), the MBT walking shoes for stage 2(group2) under the same conditions. There was one week interval between stages. 1. There was no significant difference in the energy consumption and the heart rates between two groups. Group 1 showed a higher energy consumption and heart rates than Group 2 under the speed of 4.0 mph. On the other hand, Group 2 showed higher ones over the speed of 4.0 mph. 2. There was no significant difference in the rating of perceived exertion and lactic acid density in blood between two groups. But Group 2 showed a lower fatigue strength than Group 1. 3. Group 2 showed a higher muscle activity with EMG than group 1, especially at the speed of 2.0, 2.5, 3.0, 3.5 mph in quadratus lumborum muscle and at 4.0mph in tibialis anterior muscle. In conclusion, we are less tired in MBT shoes than in general sporting shoes. Also, we can dorsiflex better in the ankle joint, straighten the lumbar region well and walk erect in MBT shoes. Specially, when it walks slowly, it is favorable in an erection walk and when it walks quickly, we have advantage of obesity management.