• Journal of Korean Society of Industrial and Systems Engineering
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• v.39 no.4
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• pp.117-124
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• 2016

Stress is resistance to stimuli to destroy a balance of mind and body in order to maintain an original steady state : A type of response and avoidance. Mild stress, which happens in tension, has a positive effect to improve concentration, but most of stress is likely to be a main factor to damage health. This is because it causes physical ailments and psychological diseases (e.g., depression, anger, frustration, loneliness, and anxiety). The purpose of this study is to analyze the difference between two groups, daytime and night university students, on ego-state, stressors, and stress coping types to improve their academic achievement by reducing their stress. There were 266 university students, who participated in a survey from November 30, 2015 until September 30, 2016. The study employed three measuring instruments : Ego-gram, stressor scale, and stress coping type scale. All the collected data were analyzed through regression analysis and t-test. The results of the regression analysis showed no significant differences in ego-state, stressors, and stress coping types between two groups. However, the results of t-test showed significant difference between the two groups : In terms of ego-state, a CP (Critical Parent) average of the night university students was significantly higher than the daytime university students'. Also, there is a significant difference in employment, future issues, and economic issues : the daytime university students considered employment and future issues more serious, while the night university students had more mental burdens of economic issues. When it comes to coping stress types, there was no significant difference between the two groups.

• Sleep Medicine and Psychophysiology
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• v.6 no.2
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• pp.116-125
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• 1999

Objectives: The purpose of this study is to investigate the effect of exercise load on sleep structure and stress hormone secretion during sleep. Methods: Five male physical education students were included in this study after giving their written, informed consents in the Research Institute for Sports Science at the University of Hanyang. All subjects have performed for at least 3 years in a regular aerobic exercises such as football, basketball, and running. The subjects were divided into three groups ; NOE(non-exercise), MDE(middle duration exercise), LDE(long duration excercise). MDE group maintained a total of 120 min exercise, and LDE group maintained a total of 300 min exercise by football, basketball or badminton. All subjects were acclimatized to the experimental sleep condition by spending one night under expermental conditions, including the placement of an intravenous catheter. During the subsequent night(24:00-08:00), somnopolygraphic sleep recordings were obtained, and blood for measuring growth hormone, cortisol, testosterone, and $\beta$-endorphin was collected every 120 min throughout the night. Blood samples were obtained from prominent forearm veins of subjects. Then, the samples were immediately placed in ice and centrifuged within 10 min at 3000 rpm at $4^{\circ}C$. Statistical analyses were performed using the SPSS/$PC^+$. Data were analyzed by one-way ANOVA with repeated measures. Results: No significant differences among groups were observed in sleep latency, total sleep time, stage 2 sleep, and slow wave sleep. However, daytime exercise produced significant changes in stage 1 sleep, REM sleep, stage 2 sleep latency, REM sleep latency and sleep efficiency. Stage 1 sleep, stage 2 sleep latency, and REM sleep latency significantly increased in LDE compared to those of NOE and MDE groups. But the amount of REM sleep significantly decreased in LDE. Sleep efficiency of MDE was higher than those of NOE and LDE. The blood concentrations of growth hormone, testosterone, and cortisol during night sleep were significantly lower in LDE than in NOE. $\beta$-endorphin concentrations in blood during night sleep were not different among groups. Conclusion: The daytime exercise load was significantly related to sleep structure and stress hormone secretion during night sleep. Long duration exercise showed a harmful effect on sleep structure and hormone secretion. However, middle duration exercise had a beneficial effect on sleep structure and hormone secretion during sleep.

• Journal of Korean society of Dental Hygiene
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• v.4 no.1
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• pp.1-17
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• 2004

The purpose of this study is to investigate the actual condition of consciousness that the students in Dept. of dental hygiene who will be engaged in dental hygiene at a dental office in the future have about a clinical training, to see whether there is any difference between the results, and then to provide fundamental data which can be helpful to develop more effective clinical training programs. For this, we investigated consciousness, that 114 daytime school students and evening school students(76 daytime school students and 38 evening school students) in Dept. of dental hygiene in J college have, using questionnaires on clinical training with Self-Administrated Method. SPSS 12.0 for Windows was used to analyze all of the questionnaires, and the results analyzed at meaningful level a=.05 are like followings: 1. The degree of satisfaction on clinical training was high as average 3.30 ; it was high in case of night training as 3.34, and of a dental office in a general hospital and an university hospital as 3.83. The degree of stress caused by clinical training was high as average 3.30, and it means that they are under relatively heavy pressure ; it was shown they got the most heavy stress as 3.39 at night, as 3.68 at a dental clinic 2. The students showed the highest tendency to recognize that clinical training is needed "for learning various clinical case experiences" as average 3.54 ; the students trained at daytime showed the highest average 3.55, and at a clinical hospital, the highest average 3.64. 3. In the study on an actual condition of consciousness about clinical training according to class difference by time(at day time and at night), there is meaningful difference between two kinds of class ; the students trained at day time showed average 2.68 that they don't like to attend, on the other hand the students at night showed higher average 2.84(p<.05). In the study on an actual condition of consciousness about clinical training according to the institutions they are trained, there is meaningful difference at satisfaction on learning method and amount of assignment : they show the highest degree of satisfaction on the learning method in case of working at a dental office in a general hospital and an university hospital as average 3.3(p<.0.1) ; the amount of assignment was shown most high at a dental clinic and a dental office in a general hospital and an university hospital as average 3.00 each(p<.05). 4. In the study of the degree of satisfaction on the clinical training, it has relatively high connections with learning contents(r=.656), learning methods(r=.497), special lessons and supplementary lessons(r=.472), the case they don't like attend at work (r=-.439), discriminatory treatment(r=-.25l), respectability on the senior dental hygienists(r=.464), a social status of a dental hygienist(r=.213), the degree of satisfaction from the relationship with other dental hygienists(r=.274), the degree of understanding which clinical training institutions have on the trained students(r=.494), trainers' ability to teach the students(r=.499). enthusiasm on guiding (r=.523), the amount of assignment(r=.333). 5. In the study on stress they got from a clinical training, it has relatively high connections with learning contents(r=-.399). learning methods(r=-.536), comprehension on training program(r=-.208), special lessons and supplementary lessons(r=-.306), the case they don't like attend at work(r=.467), discriminatory treatment(r=.366), respectability on the senior dental hygienists(r=-.341), a social status of a dental hygienist(r=-.l97), the degree of satisfaction from the relationship with another dental hygienists(r=-.289), the degree of understanding which clinical training institutions have on the trained students(r=-.430), trainers' ability to teach the students(r=-.396), enthusiasm on guiding(r=-.495).

• Journal of Environmental Science International
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• v.28 no.12
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• pp.1101-1110
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• 2019

This study investigated Post-Occupancy Evaluation (POE) of cherry blossom trails 'Cherry Road' in Daegu Catholic Univ. campus, at Gyeonsan-city, Korea. The evaluation focused on image preference and satisfaction of users i.e., students, using questionnaire surveys. A total 201 questionnaire samples were analyzed and most of the respondents were in the age group of 20. Frequency analysis was conducted on demographics, use behavior, reliability, and means. Factor analysis and multiple regression analysis were conducted for user satisfaction and image preference. Over 80% of visitors came with companions during daytime. The most common motives for use were strolling and walking, event and meeting, passing. For user satisfaction the mean scores were highest for landscape beauty (4.22), image improvement (4.14), campus image (4.08). Night lighting facility received the lowest score (3.32). Factor analysis concerning user satisfaction was categorized into environment-human behavior and physical factors. Multiple regression analysis showed that the overall satisfaction of user was significantly influenced by five independent variables: 'harmonious' (β=.214), 'night lighting facility' (β=.173), 'landscape beauty' (β=.208), 'lawn care' (β=.154), and 'walking trails' (β=.123). The mean scores of image variables were highest for 'beautiful' (5.81), 'bright' (5.67), and 'open' (5.64). The lowest scores was for 'quiet' (4.47). Exploratory factor analysis led to three factors being categorized: aesthetics, comforts, and simplicity. Result of multiple regression analysis indicated that the preference of space image was significantly influenced by five variables: 'bright' (β=.397), 'refreshing' (β=.211), 'cool' (β=.219), 'clean' (β=.182), and 'natural' (β=.-142). Hence, Cherry Road has a high level of user satisfaction and image evaluation, which is interpreted as having various cultural events and value for students on campus. To improve the satisfaction of Cherry Road in the future, it is necessary to secure night lighting, to manage trash cans, and to secure rest space.

• Sleep Medicine and Psychophysiology
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• v.9 no.2
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• pp.106-114
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• 2002

Objectives: Daytime sleepiness is a common symptom and is associated with sleep behavior, sleep deprivation, and night shift, etc. It is also one of the most important symptoms of sleep disorders like obstructive sleep apnea (OSA). According to our survey on Korean literature, a few studies have dealt with daytime sleepiness, and we have not been able to locate any study comparing normal subjects with polysomnography-proven sleep disorder patients regarding daytime sleepiness. We aimed at comparing daytime sleepiness among normal healthy daytime workers, medical students being expected to have daytime sleepiness due to chronic sleep deprivation, and patients having sleep disorders diagnosed with polysomnography. We also studied the association between subjective daytime sleepiness and objective polysomnographic findings in patients with sleep disorders. Methods: One hundred three hospital workers, 137 medical students, and patients with sleep disorders were studied. Sleep disorders included OSA, periodic limb movements in sleep (PLMS), insomnia, and narcolepsy. The degree of subjective sleepiness in each group was measured by the Korean version of Epworth sleepiness scale and compared. The relationship between polysomnographic findings reflecting severity of sleep disorder in each patient group and subjective sleepiness was analyzed. As for patients with narcolepsy, the relationship between the mean sleep latency and subjective sleepiness was studied. Results: There was a significant difference of ESS score (F=68.190, dF=5.752, p<0.001) among daytime workers, medical students, and sleep disorder patients. In OSA patient group, the degree of the sleepiness had no significant correlation either with mean O2 satuaration (p=0.062) or with RDI (p=0.807). In PLMS patient group, there was no correlation between periodic limb movement index (PLMI) and subjective sleepiness (p=0.761). In narcolepsy patient group, the subjective sleepiness had no correlation with mean sleep latency measured with MSLT (p=0.055). Conclusion: We found a significant difference of subjective sleepiness among daytime workers, medical students, and patients with sleep disorders. However, no consistent correlation was found between severity of subjective sleepiness and objective polysomnographic findings reflecting severity of each sleep disorder. This research confirms that the evaluation of subjective sleepiness is important clinically, but it cannot substitute the objective measures such as nocturnal polysomnography and MSLT.

• Physical Therapy Korea
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• v.15 no.4
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• pp.43-49
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• 2008

The objective of this study was to compare the differences on the activity and power of the wrist flexors and extensors in subjects before the use of a wrist extension splint, after nighttime wearing of the splint, and after daytime wearing of the splint. Ten healthy male and ten healthy female students (mean: $22.4{\pm}1.2$ years old) volunteered to wear custom-made wrist splints either during the night or during the day, The hand force of the wrist flexor and extensor, and grip force were measured by PowerTrack II and Dynatron, respectively. At the same time, the activities of the wrist flexor and extensor were recorded by' surface electromyography. The maximal hand force and motor unit recruitment of the flexor carpi ulnatis (FCU) increased significantly (p<.05) when tile subjects wore the wrist splints during the daytime, but the maximal hand power of the FCU decreased with nighttime use of the splints. The maximal hand power and motor unit recruitment of the extensor carpi radialis (ECR) and the ECR/FCU ratio decreased both during nighttime and daytime use. The decrement of the ECR/FCU ratio was significant (p<.05). Wearing a wrist extension splint during nighttime led to the maintenance of a lengthened position of the wrist flexor, resulting in the wrist flexor becoming weak. Wearing a wrist extension splint during the day induced the wrist flexors to be greater. In healthy people, the imbalance between the wrist flexors and extensors may be caused by the use of a wrist extension splint. This study indicates that therapists have to consider whether a splint will be effective, as well as the wearing time, when prescribing splints to people with problems of the musculoskeletal system.

• Sleep Medicine and Psychophysiology
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• v.7 no.1
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• pp.51-59
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• 2000

Objectives: It is been reported that sleep patterns change significantly during the adolescent years. In Korea, the sleep patterns of adolescents have not been investigated systematically. The authors performed preliminary study about sleep patterns of middle and high school students in Seoul before nationwide study. Methods: The authors selected one of middle and high schools located in typical middle class area in Seoul. The study was performed during the periods when examination or vacation did not affect the sleep cycle. Fifty to one hundred male and female students were selected from one school year each. One of investigators explained the purposes and methods of this study to the students and gave additional explanation to the teachers in charge. We designed a questionnaire for subjects to describe the nap time, bedtime, sleep latency, total sleep time, rise time and sleep efficiency, and the students recorded sleep logs for seven days including weekend. Eight hundred three students answered the questionnaires. Among them, we selected the subjects who recorded sleep logs at least three days and filled up the questionnaires completely. Finally, seven hundred seventy one subjects were included in this study. Weekend was defined as the time from Saturday morning to Sunday morning, and Sunday sleep patterns were treated separately. Results: Across the six school years, school-night bedtimes were delayed one hundred twenty four minutes and school-ight rise times were advanced by thirty five minutes. School-night total sleep times were decreased by one hundred fifty eight minutes, and weekend bedtimes were delayed by one hundred twenty five minutes. The students tended to oversleep on weekends, and the mean of weekend oversleep was ninety six minutes. But, bedtime in weekends was not delayed. Daytime sleep, sleep latency and sleep efficiency were not changed greatly across six school years. Total sleep time of female students was decreased significantly between third middle school year and first high school year, but time of male students was decreased between first and second high school year. Conclusion: It is supposed that sleep deficiency of middle and high school students in Seoul was due to delayed bedtimes and advanced rise times across the school years.

• Journal of the Korean Society of School Health
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• v.36 no.3
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• pp.113-125
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• 2023

Purpose: The purpose of this study is to develop a model for predicting mental health risk among adolescents based on health behavior information by employing a hybrid machine learning method. Methods: The study analyzed data of 51,850 domestic middle and high school students from 2022 Youth Health Behavior Survey conducted by the Korea Disease Control and Prevention Agency. Firstly, mental health risk levels (stress perception, suicidal thoughts, suicide attempts, suicide plans, experiences of sadness and despair, loneliness, and generalized anxiety disorder) were classified using the k-mean unsupervised learning technique. Secondly, demographic factors (family economic status, gender, age), academic performance, physical health (body mass index, moderate-intensity exercise, subjective health perception, oral health perception), daily life habits (sleep time, wake-up time, smartphone use time, difficulty recovering from fatigue), eating habits (consumption of high-caffeine drinks, sweet drinks, late-night snacks), violence victimization, and deviance (drinking, smoking experience) data were input to develop a random forest model predicting mental health risk, using logistic and XGBoosting. The model and its prediction performance were compared. Results: First, the subjects were classified into two mental health groups using k-mean unsupervised learning, with the high mental health risk group constituting 26.45% of the total sample (13,712 adolescents). This mental health risk group included most of the adolescents who had made suicide plans (95.1%) or attempted suicide (96.7%). Second, the predictive performance of the random forest model for classifying mental health risk groups significantly outperformed that of the reference model (AUC=.94). Predictors of high importance were 'difficulty recovering from daytime fatigue' and 'subjective health perception'. Conclusion: Based on an understanding of adolescent health behavior information, it is possible to predict the mental health risk levels of adolescents and make interventions in advance.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.22 no.3
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• pp.182-191
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• 2011

Objectives: The aim of this study was to investigate the sleep patterns of South Korean elementary school children and whether the differences in sleep patterns were related to behavior, emotional problems, attention and academic performance. Method: This study included a community sample of 268 boys and girls from fourth-, fifth- and sixth-grade classes in a South Korean metropolitan city from November to December 2010. The primary caregivers completed a questionnaire that included information on demographic characteristics, as well as the Child's Sleep Habit Questionnaire (CSHQ), the Korean version of Child Behavior Checklist (K-CBCL), the Korean version of the Learning Disability Evaluation Scale (K-LDES), the Korean version of ADHD Rating Scale (K-ARS) and the Disruptive Behavior Disorder Scale (DBDS). We conducted analyses on the CSHQ individual items, between the subscales, on the total scores and on the K-CBCL, the K-LEDS, the K-ARS and the DBDS. Results: Based on the findings from the CHSQ, the subjects had significantly higher scores for bedtime resistance ($9.18{\pm}2.17$), delayed sleep onset ($1.32{\pm}0.62$), the sleep duration ($4.19{\pm}1.52$) and daytime sleepiness ($14.10{\pm}3.55$) than the scores from the previous reports on children from western countries. The total CHSQ score showed positive correlations to all subscales of the K-CBCL : withdrawn (r=0.24, p<.005), somatic complaint (r=0.24, p<.005) and anxious/depressive (r=0.38, p<.005). Bedtime resistance was associated with oppositional defiant disorder (r=0.15, p<.05) and a positive correlation was demonstrated between sleep anxiety and the oppositional defiant disorder score (r=0.13, p<.05), night waking and the conduct disorder score (r=0.16, p<.05). Delayed sleep onset was related with low performance on the K-LDES with respect to thinking (r=-0.17, p<.05) and mathematical calculation (r=-0.17, p<.05). Conclusion: The results of this study reconfirm Korean children's problematic sleep patterns. Taken together the results provide that the reduced sleep duration and disruption of sleep pattern can have a significant impact on emotion, behavior, performance of learning in children. Further studies concerning more diverse psychosocial factors affecting sleep pattern will be helpful to understanding of the sleep health in Korean children.