• Korean Journal of Psychosomatic Medicine
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• v.29 no.2
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• pp.111-120
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• 2021

Objectives : Shift work has been known to cause various health problems by making it difficult for humans to adapt to their natural circadian rhythms. In particular, shift workers tend to complain of sleep difficulties associated with work schedules, and sometimes use alcohol as a self-medication to induce sleep. To date, no clear mechanism has been identified regarding the link between shift work and sleep, between shift work and drinking. This study aims to confirm the relationship between shift work and sleep, and to analyze whether the change in sleep caused by shift work causes drinking. Methods : This study included 11360 people (5704 men and 5656 women) among the Korean National Health and Nutrition Survey data in 2014, 2016 and 2018. The work type between 6am-6pm was defined as day work, and other work types were defined as shift work. Using logistic regression analysis, the relationship between shift work and sleep quality, shift work and high risk drinking, drinking amount at 1 time, drinking frequency were analyzed. In addition, we analyzed whether sleep mediates the relationship between shift work and drinking using mediated analysis. Results : Shift work showed a significant negative relationship with sleep quality in men and women (male OR=1.37, 95% CI 1.11-1.70, female OR=1.26, 95% CI=1.05-1.50). There was no significant relationship between shift work and alcohol in the case of men, but in the case of women, there was a significant positive relationship between shift work and the number of alcohol consumption (OR=1.34, 95% CI=1.04-1.72). When mediation analysis was conducted, it was found that women's sleep quality partially mediated the relationship between shift work and the frequency of drinking. Conclusions : The results of this study suggest that shift work causes sleep difficulties, and in the case of women, drinking can be induced through the partial mediating effect of sleep. Considering that women are more likely to choose drinking as a coping method for sleep problems, more active interventions for female shift workers are needed.

• Safety and Health at Work
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• v.4 no.3
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• pp.160-165
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• 2013

Background: Occupational accidents are unplanned events that cause damage. The socio-economic impacts and human costs of accidents are tremendous around the world. Many fatalities happen every year in workplaces such as electricity distribution companies. Some electrical injuries are electrocution, electric shock, and burns. This study was conducted in an electricity distribution company (with rotational 12-hour shift work) in Iran during an 8-year period to survey descriptive factors of injuries. Methods: Variables collected included accident time, age of injured worker, employment type, work experience, injury cause, educational background, and other information about accidents. Results: Results indicated that most of the accidents occurred in summer, and 51.3% were during shift work. Worker negligence (malpractice) was the cause of 75% of deaths. Type of employment had a significant relationship with type of injuries (p < 0.05). Most injuries were electrical burns. Conclusion: High rate of accidents in summer may be due to the warm weather or insufficient professional skills in seasonal workers. Shift workers are at risk of sleep complaints leading to a high rate of work injuries. Acquiring knowledge about safety was related to job experiences. Temporary workers have no chance to work all year like permanent workers, therefore impressive experiences may be less in them. Because the lack of protective equipment and negligence are main causes of accidents, periodical inspections in workshops are necessary.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1998.03a
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• pp.148-153
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• 1998

In order to control thermal deformation of machine origin of machine tools due to internal and external heat sources, the real-time compensation system has been developed. First, GMDH models were constructed to estimate thermal deformation of machine origin for a vertical machining center through the measurement of deformation data and temperature data of specific points on the machine tool. Thermocouples and gap sensors are used respectively for measurement. These models are nonlinear equations with high-order polynomials and implemented in a multilayered perceptron type network structure. Secondly, work origin shift method were developed by implementing digital I/O interface board between CNC controller and IBM-PC. The work origin shift method is to shift the work origin by the compensation amounts which is calculated by pre-established GMDH model. From the experimental result, thermal deformation of machine origin was reduced to below $\pm$5${\mu}{\textrm}{m}$.

• Journal of the Korean Society of Food Culture
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• v.34 no.4
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• pp.486-494
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• 2019

There are an increasing number of reports that job related factors are associated with hypertension, sleep deprivation, obesity and diabetes. This study analyzed the relationship of working type, working hours and the prevalence of metabolic syndrome. The study's subjects were 2,777 employees (1,446 males and 1,331 females) over 19 years old and their data was from the Korea National Health and Nutrition Survey (2015). The type of work was divided into day work and shift work. The working hours were divided into less than 40 hours, 40 to 49 hours, 50 to 59 hours and 60 hours or more per week. As a result of this study, the prevalence of metabolic syndrome was 26.4% of the males and 19.1% of the females. Generally there was no relationship between metabolic syndrome and type of work (day work and shift work). As a result of analysis of working hours and metabolic syndrome, the workers who worked 40-49 hr were associated with a decreased prevalence of metabolic syndrome as compared to that of workers who worked less than 40 hr (odds ratio: 0.47, 95% confidence interval: 0.24-0.95, p<0.05). Further, positive relationships were found between the number of work hours and the prevalence metabolic syndrome for specific females who worked over 40 hr/wk. It can be concluded from the results that it is important to help workers avoid metabolic syndrome through setting appropriate work hours.

• Annals of Occupational and Environmental Medicine
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• v.35
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• pp.30.1-30.13
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• 2023

Background: Dysmenorrhea and menstrual cycle changes occur in women working shifts. Circadian rhythm disruption and sleep disturbances associated with shift work leads to health problems. We identified chronotypes and the occurrence of insomnia among newly employed university hospital nurses and investigated the association of these factors with menstrual problems. Methods: We conducted pre-placement health examinations for shift workers using self-reported questionnaires between 2018 and 2020. A total of 463 nurses were included in the study. Sociodemographic data, shift work experience, and information on insomnia were collected from health examination data. In addition, details regarding chronotype, dysmenorrhea, irregular and abnormal menstrual cycles, amenorrhea, and contraceptive use were obtained from the questionnaire. Multiple logistic regression analysis was performed to study the association between chronotype, insomnia, and menstrual problems after controlling for age, body mass index, contraceptive use, amenorrhea, and prior shift work. Results: The prevalence rates of dysmenorrhea, irregular menstrual cycles, and longer menstrual cycles were 23.8%, 14.9%, and 4.1%, respectively. The risk of dysmenorrhea increased in the evening-type (odds ratio [OR]: 3.209; 95% confidence interval [CI]: 1.685-6.113) and those with insomnia (OR: 1.871; 95% CI: 1.074-3.261). Additionally, the risk of an irregular menstrual cycle (OR: 2.698; 95% CI: 1.167-6.237) increased in the evening-type, and the risk of a longer menstrual cycle (OR: 4.008; 95% CI: 1.354-11.864) increased in individuals with insomnia. Conclusions: Our findings suggest that dysmenorrhea is promoted in the evening-type and insomnia individuals. There may be an increased risk of irregular menstrual cycles among evening-type nurses and an increased risk of longer menstrual cycles among those with insomnia. Therefore, factors such as evening-type and insomnia should be considered for the prevention of menstrual problems in women performing shift work.

• Journal of Physiology & Pathology in Korean Medicine
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• v.18 no.2
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• pp.344-348
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• 2004

This study regarded irregular life styles such as nigh-shifts as contrary to the norm advised in the rules of Yang-saeng to analyze the problems brought about in relation to the concept of 'Yin-deficiency syndrome'. Yin-deficiency survey was given to sales workers on a big shopping mall in Seoul to compare the measurements of daytime workers to those of nigh-shift workers. The measurement of complaining symptoms related to Yin-deficiency of daytime workers and night-shift workers were compared, In comparison of the daytime workers and the night-shift workers, night-shift workers showed higher measurements than the daytime workers in the item of irritable fever on the five Hearts, flushing of the zygomatic region in the afternoon, tidal fever, dizziness, insomnia, yellow and scanty urination, and constipation. Especially tidal fever, insomnia, and constipation showed statistically significant difference. The total of ten items consisting of Yin-deficiency-related symptoms showed statistically significant high score in night-shift workers than the daytime workers. 'Factors for deficiency-type Heat' consisting of irritable fever on the five Hearts, flushing of the zygomatic region in the afternoon, tidal fever, and dried mouth and throat showed statistically significant high score in night-shift workers than the daytime workers. 'Accompanying factors' consisting of night sweats, emaciation, dizziness, insomnia, yellowish and scanty urination, and constipation also showed statistically and significantly high score in night-shift workers than the daytime workers. From the above results that night-shift workers show high degree of Yin-deficiency than daytime workers, and those overworking irregularly also show high degree of Yin-deficiency than those who work for adequate amount of time regularly implies that sitting up at night for work and sleeping at daytime, excessive work, and irregular life styles all function as high-risk factor for Yin-deficiency.

• Korean Journal of Occupational Health Nursing
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• v.18 no.1
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• pp.106-115
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• 2009

Purpose: Occupational stress is a determinant risk factor for cardiovascular disease and work disability. This study aims to describe occupational stress and identify its related factors among aged security guards. Methods: A random sample of 76 aged security guards were interviewed by three research assistants. The criteria of the subjects were as follows : 50 or older male with 40 or more working hours a week working with colleagues ranged from 3 to 50. The data were collected in September, 2007 and analyzed by multiple regression using SAS Version 9.1. Results: The mean score of occupational stress among aged security guards was 47.2. The mean scores of its sub-scales were 31.3(physical environment), 33.8(occupational demand), 80.8occupational control), 44.6(interpersonal conflict), 51.3 (occupational insecurity), 53.6(occupational system), 57.5(lack of reward), and 30.3(work environment). The scores of occupational control, interpersonal conflict, and occupational insecurity were higher than the scores of Korean average occupational stress sub-scales. Significant variables affecting occupational stress and its sub-scales were work place, work type, and employment type. Conclusion: In order to reduce occupational stress among security guards, sufficient occupational control and interpersonal conflict control, appropriate reward, and employment stability should be considered. Also long working hours and work shift should be improved.

• The Journal of the Korea Contents Association
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• v.17 no.3
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• pp.261-273
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• 2017

The purpose of study is to measure nurses' empathy levels and to examine the effects of their empathy levels on their life and job satisfaction. The questionnaire was administrated to 150 nurses working in hospitals in Busan. The questionnaire consists of three factors : empathy level, life satisfaction, and job satisfaction. Nurses are classed into two : shift work nurse and non-shift work nurse by their work type. 144 out of 150 questionnaires were used for the analysis with IBM SPSS Statistics 21. The shift work nurses with higher empathy levels showed higher job satisfaction. The non-shift work nurses with higher empathy level revealed higher life satisfaction. Interestingly, while empathy level had positive effects on shift work nurses' job satisfaction(${\beta}=.282$, p=.006), it also had impact on non-shift work nurses' life satisfaction positively(${\beta}=.252$, p=.048). As results show, nurses' life and job satisfaction were positively related to their empathy levels. Given the fact that lack of nurses' empathy often lead to conflicts with patients, in order to improve nurses' job performance, we need a new perspective of understanding the important role of empathy in nurses' job satisfaction and life satisfaction.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.178-187
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• 2021

This study is a descriptive correlation study to identify the factors affecting life satisfaction for shift service workers and is a secondary data analysis study using the raw data from the Fifth Korean Work Environment Survey. Five hundred and seventy-seven study subjects were selected from 20-year-old wage workers who had more than one year of work experience at the time of the survey and had worked more than 40 hours a week. The analysis used SPSS 23.0 WIN, including a t-test, one-way ANOVA by Scheffe test, Pearson's correlation oefficients, and Hierarchical multiple regression analysis. Regarding the general characteristics of the subjects, there was a difference in life satisfaction according to age, educational level, industrial type, and subjective health status. The higher the work-life balance and work satisfaction of the shift service worker, the higher the life satisfaction. In addition, social support had a moderating effect on the relationship between work-life balance and work satisfaction of shift service workers. Active social support, work satisfaction, and work-life balance improvement promotion programs were developed and applied to shift work service workers considering the factors influencing life satisfaction, thereby improving the life satisfaction of work shift service workers.

• Journal of applied mathematics & informatics
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• v.33 no.5_6
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• pp.485-502
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• 2015

A computational method for solving singularly perturbed boundary value problem of differential equation with shift arguments of mixed type is presented. When shift arguments are sufficiently small (o(ε)), most of the existing method in the literature used Taylor's expansion to approximate the shift term. This procedure may lead to a bad approximation when the delay argument is of O(ε). The main idea for this work is to deal with constant shift arguments, which are independent of ε. In the present method, we construct the formally asymptotic solution of the problem using the method of composite expansion. The reduced problem is solved numerically by using operator compact implicit method, and the second problem is solved analytically. Error estimate is derived by using the maximum norm. Numerical examples are provided to support the theoretical results and to show the efficiency of the proposed method.