• Journal of Korean Academy of Nursing
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• v.21 no.2
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• pp.129-149
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• 1991

Circadian rhythm is entrained in the 24-hour time interval by periodic factors in the environment, known as zeitgeber. But most rotating work schedules are outside the range of the entrainment of the pacemaker timing the human circadian sleep - wake cycle. It has been postulated that physiological and emotional disturbances occur in most human functions when the circadian rhythm is disturbed. So application of circadian principles to the design of shift schedules can aid in maintaining the temporal integrity of the circadian system and thereby minimize for the shift worker any detrimental consequences of circadian disruption. This study was a quasi-experimental study to test the effect of shift intervals for the clinical nurse on the circadian rhythm. Twenty nurses newly employed in general units of two hospitals were selected as an experimental group and twelve college nursing students as a control group. Both groups were selected according to an established criteria using a purposive sampling technique. Ten subjects were assigned to a weekly shift group and another ten to a biweekly shift group engaged in a semi -continuous shift schedule(sunday off) with a backward direction, that is, morning -evening - night shift. The control group worked a morning shift for 42 days. Oral temperature rhythm, waking tim, sleep - wake cycle, fatigue, and mental performance were measured during the experimental period. The data collection period was from April 30, 1990 to June 10, 1990. MANOVA, paired t-test, ANOVA, and Student Newman Keuls method were used for statistical analysis. The results are summarized as follows. 1. Phase delay in the acrophase of temperature rhythm was shown according to the backward rotating shift. A complete adaptation to work on the night shift was achieved between the sixth and ninth day of the night shift. 2. There was no difference in either waking time or sleep- wake cycle according to the duration of the working day for every shift group. Significant difference was found in the waking time and the sleep -wake cycle for subjects on the morning, evening, and night shift in both of the shift groups(weekly shift group : λ＝0.121, p＜0.01, λ＝0.112, p＜0.01, biweekly shift group : λ＝0.116, p＜0.01, λ＝0.084, p＜0.01). 3. There was no difference in fatigue between the first working day and the last working day for the control group and for the biweekly shift group. In the weekly shift group, physical fatigue was significantly different for the first day and the sixth day of the night shift(t＝-2.28, p＜0.05). Physical fatigue and total fatigue on the first day of the night shift showed a significant difference among the control group, the weekly shift group, and the biweekly shift group(F＝5.79, p＜0.01, F＝4.56, p＜0.05). There was a significant difference between the shift groups and the control group(p＜0.05), Physical fatigue, neurosensory fatigue and total fatigue on the last day of the night shift showed a significant difference among the control group, the weekly shift group, and the biweekly shift group(F＝12.65, p＜0.01, F＝7.77, p＜0.01, F＝9.68, p＜0.01). There was a significant difference between the shift groups and the control group(p＜0.05). 4. No difference in mental performance was seen between the first day and the last day of work in each case. An arithmatic test on the first day of the night shift revealed a significant difference among the control group, the weekly shift group, and the biweekly shift group(F＝3.79, p＜0.05). There was a significant difference between the shift groups and the control group(p＜0.05) . The digital symbol substitution test and the arithmetic test on the last day of the night shift showed a significant difference among the control group, the weekly shift group, and the biweekly shift group(F＝3.68, p＜0.05, F＝5.55, p＜0.01), and both showed a significant difference between the shift groups and the control group(p＜0.05). Accordingly, this study showed that during night duty, the waking time, sleep- wake cycle, and fatigue increased and mental performance decreased compared with morning and evening duty. It was also found that the weekly shift group had a higher fatigue score on the sixth day of night duty as compared to the -first day, but the waking time, sleep- wake cycle, and mental performance revealed no difference for the duration of the night duty or between shift groups, and complete adaptation of temperature rhythm was achieved between the sixth and ninth day of night duty. It is possible to conclude from these results that for intermediate circadian type in a healthy young woman, a biweekly shift system is more compatible with the circadian timing system than weekly shift system.

• Journal of the Korean Society of Food Culture
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• v.35 no.2
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• pp.156-166
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• 2020

In this study, 594 questionnaires administered to men and women residing in the capital metropolitan area who work night shifts were analyzed in order to study the effect of health information cognition on healing needs in accordance with the type of food selection criteria of the night worker. The results of confirmatory factor analysis in deriving food selection type identified four categories, a safety seeking type, a food exploratory type, a habitual seeking type, and a rational type, and the cognition types on health information were classified into physical cognition and psychological cognition. The need for healing, which was the investigated factor, was found to have a high correlation between questionnaire items with high reliable consistency. The results of this study were as follows. First, the food selection types of safety seeking type and habitual food seeking type had significant positive effects on the cognitive level of physical health information, and food exploratory type and habitual seeking type had significant positive effects on the cognitive level of psychological health information. In addition, it was shown that food exploratory type and rational type had significant positive effects on healing needs. As a result of this study, it was found that the cognition level of physical and psychological information was different according to food selection type, and the higher the cognitive level, the higher the healing needs. In particular, the result that the level of psychological health information significantly affected healing needs signifies that there is a demand to develop programs and menus that satisfy various needs related to healing and recovery from fatigue. In addition, further interest and study on the health and healing of night workers are required.

• Journal of the Korean Dietetic Association
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• v.29 no.1
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• pp.13-30
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• 2023

This study investigates the effect of working hours on the dietary behaviors and dietary quality of male industrial workers employed in rotating shifts. The survey was conducted from February to March 2022, enrolling 209 male workers operating in rotational shifts at industries in the Chungcheongnam-do region. Eating behavior and health awareness were investigated during the morning shift, afternoon shift, and night shift for the same subjects. The shift timings were found to be associated with dietary behavior, which had an impact on the dietary quality of workers. Negative effects of shift timings on diet and health were also perceived by the shift workers. The frequency of alcohol consumption was high during the morning shift, and the frequency of night time snack intake was high during the afternoon shift. During the night shift, there was decreased vegetable intake and increased ramyeon intake. Compared to the morning shift, a significant decrease in dietary quality scores was found during the night shift. The workers recognized that rotating shift work negatively affected health, eating habits and sleep. There was a high demand for providing a variety of menus and healthy night snacks in the company cafeteria. When nutritional counseling and educational health services were provided, the willingness to participate was high. Therefore, to improve the health and dietary quality of shift workers, there is a need to provide diets suitable for the working environment and the characteristics, and to provide nutrition management services.

• Safety and Health at Work
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• v.10 no.4
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• pp.512-517
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• 2019

Background: Rest breaks at work are reported to reduce fatigue and job stress. Apartment janitors in Korea who perform night shift work and work long hours can be exposed to various health problems (HPs). However, few studies have evaluated relationships between their rest breaks and HPs. This study was conducted to examine the relationships between long working hours, shift work, and insufficient rest breaks and HPs among Korean apartment janitors. Methods: Data on 1,212 selected male apartment janitors were obtained from the 3rd and 4th Korean Working Conditions Surveys. Demographic and occupational characteristics were collected using self-reported questionnaires. Rest breaks at work were classified as "sufficient" or "insufficient." Long working hours were considered as working more than 60 hours per week. Zero-inflated negative binomial (ZINB) regression was performed to investigate the effects of shift work and long working hours on HPs and the effects of rest breaks on relationships between HPs and long working hours and shift work. Results: Among those with insufficient rest breaks at work, significant associations were found between long working hours and the risk of HPs [odds ratio (OR) = 1.489; 95% confidence interval (CI) = 1.038-2.136] and work-related HPs (WRHPs) [OR 1.621; 95% CI = 1.156-2.272], and between shift work and HPs [OR = 1.603; 95% CI = 1.084-2.372]. These relationships became nonsignificant when sufficient rest breaks were provided. Conclusion: It is important to provide breaks at work to reduce HPs because of long working hours and shift work among aged workers such as apartment janitors.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.25 no.3
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• pp.418-427
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• 2015

Objectives: This study evaluated the association between work related characteristics and hypertension among white collar workers in Korea. Materials and methods: This study was based on the Third Korean Working Conditions Survey(KWCS) conducted in 2011 among workers 15 years of age or older. The total number of individuals included in the analysis was 10,365 white collar workers. Results: The prevalence rate of hypertension was 3.7% among men and 1.0% among women. In multiple logistic analysis the adjusted odds ratio showed statistically effective association to hypertension. For work related characteristics, 1.73 (95% confidence interval, 1.22-2.46) resulted for large-company workers compared with the small-company group, 2.14 (95% CI, 1.22-3.75) for the long working hours group (61 or above) compared with short working hours group(52 or below), 1.78(95% CI, 1.08-2.95) for night shift workers compared with day workers, and 1.54 (95% CI, 1.18-2.01) for high job stress workers compared with low job stress workers. Conclusions: This study showed that it is important for workers to manage their work environment in order to prevent hypertension by modifying their types of work.

• Journal of the Korea Safety Management & Science
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• v.14 no.2
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• pp.91-101
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• 2012

To decrease employees' job stress in the viewpoint of occupational health is very important to improve the productivity and quality of labor. In this study, the job stress, and it's influence on job commitment and organizational commitment were investigated by the questionnaire survey of 259 industrial workers. As results, the majority of workers were under job stress resulted from job demand, job control, and coworker's support. The work times per a week and night work had significant relationships with job demand, and the maximum negative relationship between the work times per a week and job continuous commitment was found. Job demand had the significant relationship with job affective and normative commitment, and job control had the significant relationship with job normative commitment and organizational affective commitment. Moreover, job affective and normative commitment had the significant relationship with organizational continuous commitment. Finally, it was found that cyclic organic chain was composed of work times per a week, night work, salary, job demand, job control, job affective and normative commitment, and organizational affective and continuous commitment. The results of this study indicates that reducing cyclic organic chain is urgently necessary to increase employees' job satisfaction and company commitment.

• Journal of the Korean Society of Fashion and Beauty
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• v.5 no.4
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• pp.149-157
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• 2007

Hair style was mean of visual symbol that display position or wealth about human life. Also, have spoken for cultural value as human body plastic art that speak for the age. I wished to study about modeling of hair style and interrelationship of color by analyzing systematically laying stress on color through contest creation work consisted in beauty art congress. Urpose of this study is as following. First, examines domestic' outside great council work head change by era, and studies Hair Work's change in work head. Second, Hair Color's change that appear in domestic' outside contest work head studies effect that get in work. Method of study runs parallel literature study and supporting research, utilized domestic' outside literature, connection paper, magazine, picture data etc. To literature study, and work picture data examined laying stress on work that is choosesed picture dataworld beauty use association (OMC) data etc. that appear in domestic' outside beauty art magazine to examine closely specification and stability of beauty art game style and participates in domestic and world beauty art contest. In this study, domestic' characteristic, and effect that collar gets in work head of collar that collects outside contest participating in an athletic contest hair style by ($1981{\sim}$until present) by year and appears in contest work head and in work since analyzing study forward $2007{\sim}2008$ year direction of collar. First, stream of whole color of the 1980s Brown gave highlight color point partially to basis, and was consisted of creative style and do Gold base color on the whole in Hair by Night item. Second, various Hair color was popularized in the 199Os, and Tuton's color appeared in beauty art game work, and I contributed to improve technique that step-up gradation color appears and does technique to highlight in neon orange in creative style and Hair by Night item by entrance on the stage of neuter gender color.

• Annals of Occupational and Environmental Medicine
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• v.35
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• pp.41.1-41.11
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• 2023

Background: Shift work has been reported to have several harmful effects on the human body. However, a small number of studies have evaluated the association between shift work and adverse effects on the thyroid. In our longitudinal study, we examined the causal association between shift work and the risk of hypothyroidism. Methods: A Kangbuk Samsung Cohort Study was conducted on 112,648 men without thyroid disease at baseline who were followed up at least once between 2012 and 2019. Shift work status and shift schedule types were categorized using standardized questionnaires. Hypothyroidism was defined using the reference ranges of serum thyroid-stimulating hormones and free thyroxine levels. Hazard ratios (HRs) and 95% confidence intervals (CIs) for incident hypothyroidism were estimated using Cox proportional hazards regression analyses with the daytime work group as the reference. Results: During the 501,237 person-years of follow-up, there were 6,306 incident cases of hypothyroidism (incidence density, 1.26 per 100 person-years). The multivariable-adjusted HR of incident hypothyroidism for the shift work total group that included all shifts compared with the daytime work group was 1.27 (95% CI: 1.15-1.40). For the fixed evening, fixed night, rotating shift, and other shift workers, the multivariable-adjusted HRs (95% CI) were 1.11 (0.76-1.61), 2.18 (1.20-3.93), 1.39 (1.23-1.56), and 1.00 (0.82-1.22), respectively. In subgroup analyses by age, the association between shift work and hypothyroidism was more pronounced in younger participants (< 40 years; HR: 1.31; 95% CI: 1.16-1.47). Conclusions: Our large-scale cohort study showed an association between shift work and the incidence of hypothyroidism, especially in younger workers with night shifts.

• Safety and Health at Work
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• v.11 no.3
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• pp.361-366
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• 2020

Background: This study aimed to identify the validity of breast cancer symptom questionnaire of worker's special health examination and its relationship with breast ultrasonography findings in young female night workers. Methods: The breast cancer symptom questionnaire data of worker's special health examination and breast ultrasonography results in young female shift workers who worked in one electronic manufacture company were collected from 2014 to 2018. Results: Of the 857 workers, 18 had a Breast Imaging Reporting and Database System category 4 or higher. Among other variables, shift work tenure alone was associated with the risk of having a Breast Imaging Reporting and Database System category higher than 4. The sensitivity, specificity, positive predictive value, and negative predictive value of the symptom questionnaire were 16.7%, 87.7%, 2.8%, and 98.0%, respectively. Conclusion: The current breast cancer symptom questionnaire of the worker's special health examination is inappropriate due to its low sensitivity and positive predictive value. In the future, female night workers will need alternative measures for more accurate screening for breast cancer.

• Sleep Medicine and Psychophysiology
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• v.9 no.1
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• pp.41-47
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• 2002

Objectives: In a number of simulated night shift studies, timed exposure to bright light improves sleep quality and work performance. We evaluated the effect of bright light on adaptation to night shift work with a field study. Methods: Five female nurses working shifts at Korea University Hospital were recruited for participation in this study. We investigated two series of six consecutive shift rotations comprising three day and three night shifts, using wrist Actigraphy, the Stanford Sleepiness Scale, Visual-analogue scales, STIM and tympanic membrane temperature for daytime sleep quality, alertness, subjective feeling, attention performance, and temperature rhythm. The subjects were exposed to bright light (2,500 lux) from 24:00 to 04:00 a.m. on three consecutive night shifts during the second series, whereas they worked under normal lightening (650 lux) conditions during the first series. Results: Actigraphic assessment of daytime sleep showed no significant difference between the first and third night shift in both baseline and light exposure phase. The mean lowest temperature shifted earlier during baseline phase but not during the light exposure phase. Also, the score for subjective feelings of depression, anxiety, physical discomfort and sleepiness was significantly higher in the third night shift than the first during baseline phase but not during the light exposure phase. Attention and attention switching ability was significantly improved in the third night shift compared to the first night during the light exposure phase but there were no significant changes during the baseline phase. Conclusion: This result suggests that there were no significant differences between the two phases in measures of quality of daytime sleep, but subjective feelings, attention and alertness were enhanced during light exposure. Although some placebo effects and learning effects might influence this result, bright light exposure between midnight and 4:00 a.m. may improve adaptation to night shift. In future, further controlled studies with a larger sample size, including melatonin measurement, are needed for real shift workers.