• Korean Security Journal
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• no.31
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• pp.7-24
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• 2012

In this study a practical guarding work is carried out for 180 minutes as the same as the actual guarding work that is done by nine students of the department of security services in K University in order to investigate changes in circadian rhythms during long hour guarding in bodyguards at practical sites. In the results of the tests of the heart rate variation and autonomic nervous system with the interval of 30 minutes using HRV (Heart rate variability), there are no significant differences in HRV and SDNN and that leads to maintain it stably during the guarding work for 180 minutes. In the case of TP which reflects the overall activity level in the autonomic nervous system, it shows a high significant difference (p<.05) at 90 and 120 minutes compared to that of normal states. Also, it shows a significant decrease in the level after a lapse of 120 minutes and that shows a decrease in the activity of the autonomic nervous system for the guarding work more than 120 minutes. Although differences in VLF, LF, and HF are not significant levels, these are influenced on the change in TP. The LH/HF ratio that represents the balance between the sympathetic nerve and the parasympathetic nerve shows a significant high level (p<.05) after a lapse of 30 minutes. Thus, it is considered that the concentration of the guarding work after a lapse of 120 minutes is decreased and there are some tensions and excitations after a lapse of 30 minutes since the beginning of the guarding work.

• Science of Emotion and Sensibility
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• v.1 no.1
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• pp.93-103
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• 1998

In this paper, we present change of human sensiblity when the 26 healthy female subjects were exposed with visual picture stimulus. We used Intermational Affective Picture System as the visual stimulus. The methods are AutoRegressive(AR) spectrum which is a linear method and Return Map which is a nonlinear mithod. SR spectrum may variability(HRV). The LF/HF of HRV and the variation of Return Map were analyzed from ECG signal of the female subjects. Return Map of RR intervals were analyzed by computiong the variation. When the subjets were stimulated by the pleasant pictures, LF/HF and variation were decreased compared with unpleasant stimulus, We may obtain good parameters for the measurement of the change of human sensibility for the visual picture stimulus.

• Journal of Oriental Neuropsychiatry
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• v.18 no.2
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• pp.25-34
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• 2007

Objective : This study was done to investigate the differences of HRV(Heart Rate Variability) change as the response to the emotional stimulus in each Sasang constitutions. Method : We investigated 44 healthy volunteers consisted of 10 Soyangin, 14 Soeumin and 20 Taeumin. After diagnosing the Sasang constitution by specialist of Sasang medicine, we measured the baseline emotional state(100 sec) before the stimulus, the changing emotional state(100 sec) while fearful film was being played. And we rechecked the emotional state(100 sec) while taking a rest. At last, volunteers checked the questionnaire for emotional response. We analysed ECG data with HRV-time domain and frequency domain analysis. Results : (1) There were no significant difference in Mean-RR , SDNN between each groups. (2) LF of Taeumin group significantly increased by the emotional stimulation compared with other groups. (3) There was no significant difference in TP, HF, normalized LF, normalized HF, but the variation of each period in Taeumin group was bigger than those of other groups. (4) Soeumin group reported that they felt significant disgust-emotion in the questionnaire compared with other groups. Conclusion : Taeumin group showed significant emotional changes on HRV by fear stimulus film.

• Journal of Preventive Medicine and Public Health
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• v.37 no.2
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• pp.182-189
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• 2004

Objectives : The objective of this study is to compare the circadian patterns of heart rate variability assessed by 24-hour ambulatory electrocardiographic (ECG) recordings during day shift and night shift among the workers in the 5 days-concecutive-12-hour shift in an automobile factory in Korea. Methods : The study population consisted 300 workers, who were randomly selected among the 8700 total workers in one car factory. To analyse circadian variation, the 24-hour ECG recordings (Marquette) were measured during day shift (08:00-20:00 h) and night shift (20:00-08:00 h). Analysis was performed for all time and frequency domain measures of HRV. 233 workers completed taking 24-hour ECG recordings. Results : This study shows that the 24 hourcircadian variation mainly follows work/sleep cycle rather than day/night cycle among shift workers. This study also shows that among the night shift, the circadian variation between work and sleep cycle decreased compared to the work/sleep cycle among day shift workers. All time and frequency domain parameters (except LF/HF ratio) show significantly different between work and sleep in the day shift and night shift. Conclusion : These changes in heart rate variability circadian rhythms reflect significant reductions in cardiac parasympathetic activity with the most marked reduction in normal vagal activity among the shift workers. Especially, it suggests the circadian rhytm has blunted among the night workers. The quantification of the circadian variation in HRV can be a surrogates of workers' potential health risk, as well as suggests possible mechanisms through which the shift works compromise workers' health.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.47 no.2
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• pp.43-49
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• 2010

Autonomic nervous system (ANS) acts as a control system functioning largely below the level of consciousness, and controls visceral functions. The activity of the ANS has been assessed by means of the heart rate variability (HRV). It has been reported that HRV is dependent on sex, age, body mass index, and smoking, etc. However, the effects of posture and sleep deprivation on HRV have rarely been reported. Objective of our work was to find out which posture is appropriate for stable HRV. We measured the number of sleep deprivation and HRV using power spectrum in six stages for 30 minutes. Increased low frequency (LF) power and high frequency (HF) power indicate enhanced sympathetic and parasympathetic activity, respectively. We determined the LF/HF ratio to minimize individual difference. It was found that sleep deprivation by awakening up subjects was affected by posture, which resulted in changes of LF/HF. Although LF/HF varied with time, it was more stable in sitting than in supine. In conclusion, we recommend sitting posture when measuring HRV because of less sleep deprivation resulting in less variation in LF/HF.

• Journal of Biomedical Engineering Research
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• v.40 no.2
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• pp.62-67
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• 2019

The purpose of this study was to evaluate the performance of deep neural network model in order to determine whether there is a risk factor for coronary artery disease based on the cardiac variation parameter. The study used unidentifiable 297 data to evaluate the performance of the model. Input data consists of heart rate parameters, which are SDNN (standard deviation of the N-N intervals), PSI (physical stress index), TP (total power), VLF (very low frequency), LF (low frequency), HF (high frequency), RMSSD (root mean square of successive difference) APEN (approximate entropy) and SRD (successive R-R interval difference), the age group and sex. Output data are divided into normal and patient groups, and the patient group consists of those diagnosed with diabetes, high blood pressure, and hyperlipidemia among the various risk factors that can cause coronary artery disease. Based on this, a binary classification model was applied using Deep Neural Network of deep learning techniques to classify normal and patient groups efficiently. To evaluate the effectiveness of the model used in this study, Kernel SVM (support vector machine), one of the classification models in machine learning, was compared and evaluated using same data. The results showed that the accuracy of the proposed deep neural network was train set 91.79% and test set 85.56% and the specificity was 87.04% and the sensitivity was 83.33% from the point of diagnosis. These results suggest that deep learning is more efficient when classifying these medical data because the train set accuracy in the deep neural network was 7.73% higher than the comparative model Kernel SVM.

• Journal of Environmental Science International
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• v.30 no.1
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• pp.1-10
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• 2021

The purpose of this study is to verify the physiological and psychological benefits of indoor garden to humans and to analyze the comparison according to Type A behavior pattern. The subjects included 18 male university students. Heart rate variation was used as a parameter of physiological assessment, and Semantic Differential (SD), Profile of Mood States-Brief (POMS), and State-Trait Anxiety Inventory (STAI) were used as tools for psychological evaluation. The participants were subjected to a psychological evaluation when they were present in a garden. As a result, the parasympathetic nervous activity was increased in the indoor garden. In the analysis of psychological evaluation, indoor garden improved the positive mood states and decreased negative feelings with significant changes only in Type A group. This study supported that indoor garden can have physiological and psychological relaxing effects, which could be more significant in Type A group than Type B.

• Science of Emotion and Sensibility
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• v.17 no.2
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• pp.85-90
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• 2014

The purpose of the study is to develop self-management system that people can enhance physical and psychological health through repeating by themselves to relieve work-related stress. The regular respiration can help homeostasis of heart to maintain. Also the effect can be stabilized from irregular heart rhythm by work-related stress. People have optimal respiration cycle to stabilize heart rhythm and repeat training using their RSP(respiration) time including expiration and inhalation. This system is not only offering optimal respiration training service but also finding optimal respiration cycle. The adults who have stress from work participated in verification experiment. This study expects to help those people who are workers related to call center jobs in emotional labor can relieve their stress. It can also help to enhance their own health and increase their work efficiency.

• Korean Journal of Community Nutrition
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• v.18 no.6
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• pp.599-610
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• 2013

This study was carried out to analyze the effect of a diet program for adult women on weight loss, BMI, eating habits, sleeping habits, health related indices. The subjects was 415 participants of the 10 weeks (20 time participation program). The data was collected by basic somatometry and HRV (Heart Rate Variability) / APG (Accelerated Plethysmograph) Analyzer. The average age, height, weight and BMI were 28.6 years, 162.1 cm, 62.8 kg and 23.9 $kg/m^2$, respectively. Their body types by BMI were under weight (1.2%), normal (45.8%), overweight (24.8%), mild obesity (22.7%) and obesity (5.5%). There were significant reductions of average weight (4.6 kg) and average BMI (1.75 $kg/m^2$) on the 10th week. There were positive changes in vascular age (50.4%), stress index (44.6%), fatigue index (43.9%), health index (54.5%) of the subjects during the program. There was a meaningful difference of the average variation for the vascular age, stress index, fatigue index, and health index between two groups; one improving the eating habit and the other did not (p<0.05), and also there was a meaningful difference of the average variation for the fatigue index in both groups improving the sleeping habit (p<0.05), but was not a meaningful difference of the average variation for the vascular age, stress index, and health index between two groups. There was a meaningful difference of the average variation for the vascular age, stress index, fatigue index, and health index between two groups improving both eating and sleeping habit (p<0.05). In conclusion, the weight loss program was effective on the weight loss and BMI reduction and health related indices.

• Journal of the Korean Society of Safety
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• v.28 no.3
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• pp.107-113
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• 2013

Problem solving and/or decision making process usually encountered in human living consists of a sequence of human behaviors based upon his/her knowledge. Thus, Rasmussen introduced Skill-Rule-Knowledge paradigm to countermeasure human errors that can occur in Nuclear Power Plants. Unfortunately however, it was not so easy as expected since objective evidence have not been obtainable with conventional research techniques. With the help of EEG band pawer ratio techniques, this study tried to get psycho-physiological symptoms of human errors, if any, while human beings perform knowledge-based behaviors such as simple arithmetic computations with different difficulty level. A set of simulated works was carried out with a computer station. Four kinds of arithmetic computation tasks were given to 10 health male under-graduate students on different day individually, and during the experiment, EEG and ECG was measured continuously for objective psycho-physiological analysis. According to the results, ${\alpha}$/(${\alpha}+{\beta}$) as well as ${\alpha}/{\beta}$ band power ratio were sensitive to task difficulty level which consistently decreased both. However, any one of them failed to reveal the influence of tasks with different difficulty level in the aspect of task duration time. On the contrary, Heart Rate Variability was more suggestive than expected. To make a conclusion, it can be said that band power of EEG waves will be helpful in not only assessment of work difficulty level but also assessment of workers' skill development if supported by cardiac function such as HRV.