• Journal of the Korean Society of Safety
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• v.23 no.5
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• pp.119-124
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• 2008

Many automobile assembly workers often do several cycles of tasks continuously, i.e., without breaks, to get a longer break. This is not recommended since the dose of fatigue increases exponetially with time and it takes much longer time to recover. In this study, a laboratory experiment was conducted to investigate the effect of work/rest schedules on workload of a repetitive upper-limb task. Eleven male subjects participated in the experiment, in which simulated screw driving tasks were carried out repetitively with 3 different work/rest schedules: standard breaks(1 cycle of work at a time, 60 20-s breaks), medium breaks(5 cycles of work at a time, 12 100-s breaks), and long breaks(10 cycles of work at a time, 6 200-s breaks). The result showed that medium- and long-breaks schedules significantly increased the level of perceived discomfort and %HRR as compared to the standard-break schedule. The subjects' preference was not statistically different among work/rest schedules, which might be caused from the absolutely low level of workload of the experimental tasks. From the results, it is recommended to have frequent and shorter breaks rather than infrequent and longer breaks to decrease the level of physical workload. A more expanded studies, however, should be carried out to provide more practical safety guidelines on the work practice of continuous working without breaks among automobile assembly workers.

• Korean Journal of Rural Living Science
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• v.9 no.1
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• pp.1-7
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• 1998

The purpose of this study is to investigate the effect of wearing sweat suit on sweating rate during jogging. 4 healthy female students served as subjects in the experimental chamber which was controlled 22$\pm$1$^{\circ}C$, 60$\pm$10%RH and no wind. The experimental clothes were Sweat Suit (SS) and General Suit (GE), SS was the product of R sports wear company which was consisted of long-sleeved jumper (100% polyester) and full length trousers (100% polyester) and GE were consisted of long sleeved shirt (100% cotton) and full length trousers (100% cotton). The subject wore same socks and shoes in both experimental clothes SS and GE. The subject reported at the experimental chamber at the same time on each experimental day. exchanged their clothes to the experimental clothes SS or GE, wore all sensors for the physiological measurements and had a rest in a sitting posture about 40 minutes. After rest, the subject carried out 30 min jogging on the tread mill with the speed 3.6miles/hour and during the jogging rectal temperature, skin temperatures (7 sites of the skin surface), heart rate, VO2, and evaporative weight loss were measured continuously and compared between two experimental clothes SS and GE. The major findings were as follows : The increase in rectal temperature during 30 min jogging was higher in experimental clothes SS than in GE and mean slim temperature kept higher in SS than in GE. VO2 and heart rate were a little bit higher in the later period of jogging in SS than in GE. The evaporative weight loss was greater in SS than in GE. These results indicate that the thermophysiological responses and sweating rate differs according to the wearing suit even though the subject performed same exercise.

• Journal of International Academy of Physical Therapy Research
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• v.2 no.1
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• pp.237-243
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• 2011

This study was to examine on the respiratory variables, heart rate and muscle activity between the static recovery and dynamic recovery after progressive resistance exercise to maximal point. Subjects were 15 students enrolled in N University. All were tested two times (static recovery and dynamic recovery) and were requested to perform a walking on a treadmill after progressive resistance exercise to maximal point. Electromyography(EMG) was used to monitor the muscle activity(TA: Tibialis Anterior, MG: Medial Gastrocnemius) during gait. CPEX-1 was used to measure the respiratory variables and heart rate. The dynamic recovery group was shown the significant lower heart rate than that of static recovery group at during gait. Respiratory rate showed statistically a significant difference. Electromyography(RMS, root mean square) showed a non-significant difference. But the dynamic recovery group of muscle activity was found highly in TA and MG. This study indicated that the dynamic recovery method evidenced more faster than the static recovery method. And this type of dynamic rest by walking can be a help of recovery after exercise.

• Journal of Biomedical Engineering Research
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• v.28 no.1
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• pp.1-7
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• 2007

To determine the effect of posture change on autonomic activity and to investigate valid parameters to reflex the autonomic activity from time-series pupil size data, a posture-related experiment was performed with 15 subjects, which involved measuring their electrocardiograms and pupil sizes. The experimental procedure consisted of three-sequence postures-supine, sitting and upright-for 5 minutes each, with rest sessions between postures. The subjects were notified of the entire experimental procedure. The parameters of the subjects' heart rate variability showed significant differences between the postures (heart rate: 63-70-80 beat, normalized low frequency power: 28-50-75, normalized high frequency power: 72-49-25 and ratio: 0.5-1.2-4.4 in supine-sitting-upright position respectively) as did the parameters of their mean pupil sizes (41300-53900-53700 pixels respectively) and the major frequencies (the third trend: 0.23-0.2-0.18 Hz respectively) of their pupil size variability according to changes in their autonomic activities induced by posture change. The experiment thus proved that posture change affects autonomic activity and that such activity can be estimated by the parameters of pupil size as similar as heart rate variability.

• Journal of Digital Convergence
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• v.18 no.8
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• pp.231-242
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• 2020

The thesis presents a system that continuously collects the human body's physiological vital information at rest with sensors and ICT information technology and predicts diabetes using the collected information. it shows the artificial neural network machine learning method and essential basic variable values. The study method analyzed the correlation between heart rate measurements of BCG and ECG sensors in 20 DM- and 15 DM+ subjects. Artificial Neural Network (ANN) machine learning program was used to predictability of diabetes. The input variables are time domain information of HRV, heart rate, heart rate variability, respiration rate, stroke volume, minimum blood pressure, highest blood pressure, age, and sex. ANN machine learning prediction accuracy is 99.53%. Thesis needs continuous research such as diabetic prediction model by BMI information, predicting cardiac dysfunction, and sleep disorder analysis model using ANN machine learning.

• Korean Journal of Applied Biomechanics
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• v.25 no.2
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• pp.141-147
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• 2015

Objective : This study aimed to understand how increased heart rates at the time of drop landing during a step test would affect biomechanical variables of the lower extremity limbs. Background : Ballet performers do more than 200 landings in a daily training. This training raises the heart rate and the fatigability of the lower extremity limbs. Ballet performance high heart rate can trigger lower extremity limb injury. Method : We instructed eight female ballet dancers with no instability in their ankle joints(mean ${\pm}$ SD: age, $20.7{\pm}0.7yr$; body mass index, $19.5{\pm}1.2kg/m^2$, career duration, $8.7{\pm}2.0yr$) to perform the drop landing under the following conditions: rest, 60% heart rate reserve (HRR) and 80% HRR. Results : First, the study confirmed that the increased heart rates of the female ballet dancers did not affect the working ranges of the knee joints during drop landing but only increased angular speeds, which was considered a negative shock-absorption strategy. Second, 80% HRR, which was increased through the step tests, led to severe fatigue among the female ballet dancers, which made them unable to perform a lower extremity limb-neutral position. Hence, their drop landing was unstable, with increased introversion and extroversion moments. Third, we observed that the increasing 80% HRR failed to help the dancers effectively control ground reaction forces but improved the muscular activities of the rectus femoris and vastus medialis oblique muscles. Fourth, the increasing heart rates were positively related to the muscular activities of the vastus medialis oblique and rectus femoris muscles, and the extroversion and introversion moments. Conclusion/Application : Our results prove that increased HRR during a step test negatively affects the biomechanical variables of the lower extremity limbs at the time of drop landing.

• Journal of Acupuncture Research
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• v.26 no.5
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• pp.49-56
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• 2009

Objectives : The purpose of this study was to assess the effect of Hwangryunhaedok-tang pharmacopuncture at $CV_{17}$ for reducing mental stress using power spectrum analysis of the heart rate variability(HRV). Methods : 30 healthy volunteers(control group: 15, experimental group: 15) participated in this study. After instrumentation and 5-minutes rest period, mental stress by operation was provided for 5-minutes. HRV was recorded before and after the mental stress. And then the control group rested for 15-minutes. The experimental group was injected Hwangryunhaedok-tang pharmacopuncture at $CV_{17}$ and rested for 15-minutes. And then HRV was recorded. Results : In simple rest group, LF norm and HF norm showed a significant change after mental stress. In pharmacopuncture group, LF norm, HF norm and LF/HF showed a significant change after mental stress. But there were no significant difference between two groups(p>0.05). In pharmacopuncture group, LF norm, HF norm and LF/HF showed a significant change after pharmacopuncture injection. There were significant difference between two groups(p<0.01). Conclusions : The result suggests that Hwangryunhaedok-tang pharmacopuncture at $CV_{17}$(Jeonjung) can regulate and prevent the alteration of autonomic nerve system due to mental stress.

• Journal of Oriental Neuropsychiatry
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• v.7 no.1
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• pp.39-48
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• 1996

This study was performed to investigate the effects of Qigong training after physical training stress in untrained college students For this study, 6 voluntary subjects(male 4, female 2) were chosen in untrained students of K University. they were trained by teachers during 6 weeks and tested just before Qingong training and after 6 weeks. Each subject was performed a treadmill exercise(model Q65, Quinton Co, U.S.A.) to the all-out state. During exercise stress test, electrocardiogram, heart rate were checked by stress test monitor(model Q4500, Quinton Co, U.S.A) and also oxygen uptake, maximal oxygen uptake analyzed continuously by automatic gas analysis(model QMC, Quinton Co, U.S.A). During physical training the serum were collected 3 times, pre-experimental rest time, and serum catecholamine were measured by HPLC.T-test of statistical analysis system was used in every experiment for statistical assessment. The results of T-test on these data were summarized as follow:1.Heart rate change during exercise stress test after Qigong training was shown more decreasing tendency than before training. Especially, heart rate change after Qigong training during resting periods was decreased significantly than before training.2. Oxygen uptake change during exercise stress test after Qigong training was shown more increasing tendency than before training, And also maximal oxygen uptake after Qigong training was shown more increasing tendency than before 6 weeks.3. Epinephrine level of after Qigong training was more decreased significantly than before training in all-out state. And norepinephrine level of after Qigong training was shown more decreasing tendency than before training in all-out state and after 30 minutes rest time. Above results indicate that Qigong training for 6 weeks could be effective to elevate the cardiopulmonary functions and diminish the stress responses of the physical stress.

• Korean Journal of Acupuncture
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• v.21 no.2
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• pp.161-176
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• 2004

Objectives : The purpose of this study was to investigate the effects of acupuncture stimulation and relaxation therapy on autonomic nervous system for students with examination stress by HRV, PSV and to find out relationship with anti-stress effect. Methods : The study group consists of 42 students were classified into three groups randomly : acupuncture stimulation group(male n=8, female n=6), relaxation therapy group(male n=8, female n=6) and rest group(male n=8, female n=6). Using heart rate variability and pupil size variability, we measured the value of HRT, SDNN, SDSD, LF norm, HF norm, LF/HF ratio, Pupil area, and compared the changes the sympathetic- parasympathetic activity. Measurement value were compared before and after, during midterm examination and normal times. Results : 1. HRT, LF/HF ratio, LF norm of acupuncture group was significantly decreased and HF norm were significantly increased in HRV after acupuncture stimulation at a term of examination. While variables of the other group were no significantly different. 2. SDNN of acupuncture group were significantly increased in HRV after acupuncture stimulation at normal times. 3. Pupil area, LF norm, HF norm of three group were no significantly different in PSV at a term of examination. 4. Pupil area of relaxation group were significantly decreased in PSV at normal times. While variables of the other group were no significantly different. 5. HRT of rest group were significantly decreased in HRV between three groups at a term of examination and normal times. 6. Pupil area of relaxation group were significantly decreased in PSV between three groups at a term of examination and normal times. Conclusion : The results suggest that acupuncture stimulation is associated with changed activity in the sympathetic and parasympathetic nervous system. Measurement values of HRV and PSV are suitable to estimate the activity of automatic nervous system.

• Journal of Acupuncture Research
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• v.29 no.3
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• pp.81-88
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• 2012

Objectives : The purpose of this study was to assess the effect of Taegeuk acupuncture on reducing mental stress by analyzing heart rate variability in Soyangin. Methods : Eight Soyangin-diagnosed women participated in this study. They were randomly divided into group A and group B. Each participant went through 3 sessions every week with 1 week of washout period in between each session. HRV was measured three times at every session; at baseline, after administering mentally stressful circumstances and after applying either one of simple rest, Soyangin Taegeuk acupuncture or Soeumin Taegeuk acupuncture. This study was designed as a crossover clinical trial. After same initial simple resting session for both groups at week 1, acupuncture for group A were executed in the order of Soyangin Taegeuk acupuncture and Soeumin Taegeuk acupuncture at week 2 and 3 respectively, with acupuncture for group B conducted in reverse order. Results : Simple rest and Soeumin Taegeuk acupuncture did not show the significant changes in response to LF(norm) and HF(norm) after stress stimuli. Soyangin Taegeuk acupuncture did, however, significantly decrease LF(norm) and increase HF(norm). Soyangin Taegeuk acupuncture, compared to Soeumin Taegeuk acupuncture, significantly stabilized autonomic nervous system. Conclusions : This study suggests that Soyangin Taegeuk acupuncture might be an effective means of stabilizing mental stress-induced imbalance of autonomic nervous system for Soyangin.