• Korean Journal of Construction Engineering and Management
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• v.6 no.5 s.27
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• pp.139-147
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• 2005

During a typical construction project, a contractor nay often find that the time originally available or normally expected to perform its work has been severely reduced. To finish the project by the completion date, the contractor is forced to find a way to speed up the progress of its work to compensate for the reduction in available time. The most frequent initial reaction of contractors to this situation is to increase on-site manpower by working longer time (overtime), adding more workers (overmanning), or implementing shift work (shift work) to increase the rate of progress. The goals of this study were to investigate how these three methods affect labor productivity and to quantify their impact on labor productivity by analyzing real project data collected from sheet metal contractors and mechanical contractors in the US.

• Annals of Occupational and Environmental Medicine
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• v.35
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• pp.4.1-4.11
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• 2023

Background: Shift work has been shown to increase the risk of cardiovascular disease (CVD) based on several evidences. The classic risk factors of CVD include age, hypertension, smoking, obesity and diabetes. Recently, the serum homocysteine level has been reported to be a valuable indicator of CVD risk. This study aimed to determine the variation in serum homocysteine level as a cardiovascular risk indicator among female workers according to shift work. Methods: The data of regular health examination of workers at an electronic manufacturing services company in Yeongnam region, South Korea in 2019 were examined in this study. The investigation was based on a cross-sectional study conducted on 697 female workers (199 day workers and 498 shift workers). The sociodemographic and biochemical characteristics were compared between day workers and shift workers. Through a logistic regression analysis, the odds ratio (OR) of the increased serum homocysteine level in relation to shift work was determined. Results: Compared to female day workers, female shift workers showed significantly higher level of serum homocysteine (8.85 ± 2.16 vs. 9.42 ± 2.04 μmol/mL; p = 0.001). The OR of day workers against shift workers was 1.81 (95% confidence interval [CI]: 1.25-2.63). With the adjustment of variables that may influence the level of serum homocysteine, the adjusted OR was 1.68 (95% CI: 1.09-2.60). Conclusions: The serum homocysteine level was significantly higher in shift workers than in day workers. It is thus likely to be a useful predictor of CVD in shift workers.

• Korean Journal of Occupational Health Nursing
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• v.33 no.1
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• pp.1-11
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• 2024

Purpose: This study aimed to analyze the factors influencing the well-being of middle-aged non-shift female workers using health-determinant models. Methods: This study analyzed data from the fifth Korean Working Conditions Survey (KWCS), involving 5,449 participants. A hierarchical multiple regression analysis was employed to examine the relationships between various factors and well-being. Results: The analysis identified key factors affecting well-being in middle-aged female non-shift workers, including supervisor support, presenteeism, satisfaction with the working environment, autonomy in working hours, support from coworkers, workplace discrimination, occupation, work-life balance, sleep problems, workplace size, weekly work hours, and sickness absence. This study confirms that the well-being of middle-aged non-shift female workers is influenced by factors at the individual, social, and community levels as well as by conditions related to love. Conclusion: To enhance the well-being of middle-aged female non-shift workers, it is essential to reinforce positive factors such as support from coworkers and superiors. Additionally, addressing and mitigating negatively influencing factors such as workplace discrimination and sleep problems is crucial in promoting well-being. By implementing measures to improve these aspects, organizations and policymakers can contribute to a healthier and more supportive work environment for middle-aged, non-shift female workers.

• Journal of Preventive Medicine and Public Health
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• v.54 no.1
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• pp.46-54
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• 2021

Objectives: This study explored the relationship between shift intensity and insomnia among hospital nurses. Methods: The participants were 386 female hospital nurses who underwent a special health examination for night workers in 2015. The Korean Insomnia Severity Index (ISI), indices of shift work intensity, and other covariates such as amount of exercise, level of alcohol consumption, employment duration, and hours worked were extracted from the health examination data. The indices for shift intensity were (1) number of 3 consecutive night shifts and (2) number of short recovery periods after a previous shift, both assessed over the prior 3 months. Multiple logistic regression analysis adjusted for the aforementioned covariates was performed to evaluate the association of shift intensity with insomnia, defined as an ISI score of ≥8. Results: The nurses with insomnia tended to be younger (p=0.029), to have worked 3 consecutive night shifts more frequently (p<0.001), to have experienced a greater number of short recovery periods after the previous shift (p=0.021), and to have worked for more hours (p=0.006) than the nurses without insomnia. Among the other variables, no statistically significant differences between groups were observed. Experiences of 3 or more consecutive night shifts (odds ratio [OR], 2.33; 95% confidence interval [CI], 1.29 to 4.20) and 3 or more short recovery periods (OR, 2.01; 95% CI, 1.08 to 3.73) were associated with increased odds of insomnia. Conclusions: The results suggest that decreasing the shift intensity may reduce insomnia among hospital nurses working rotating shifts.

• 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.

• Korean Journal of Occupational Health Nursing
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• v.25 no.2
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• pp.96-107
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• 2016

Purpose: The purpose of this study was to investigate the effects of shift work and hours of sleep on metabolic syndrome in Korean workers. Methods: This study used the Korean National Health and Nutrition Examination Survey data of 2014. The study included 1,579 Korean workers aged over 20. $x^2$ test, t-test, and hierarchical multiple logistic regression were used for statistical analysis of data. Results: From the univariate analysis, hours of sleep, regular work, occupational group, sex, age, marital status, education, smoking, and self-rated health were significantly related to metabolic syndrome. After adjusting demographic, occupational, and health-related variables, workers with under 6 hours/day of sleep showed higher risk for metabolic syndrome (AOR: 1.56, 95% CI: 1.01~2.44), and shift work was not significantly related to metabolic syndrome. Male laborers and workers aged 40 or older also showed higher risk for metabolic syndrome. Conclusion: Results of this study suggest that workers with under 6 hours of sleep, male laborers and workers aged 40 or older are the risk groups of metabolic syndrome. Therefore, prevention and management program for metabolic syndrome should be implemented for this population.

• Safety and Health at Work
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• v.1 no.2
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• pp.112-123
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• 2010

The paper gives an overview of the problems to be tackled nowadays by occupational health with regards to shift work as well as the main guidelines at organizational and medical levels on how to protect workers' health and well-being. Working time organization is becoming a key factor on account of new technologies, market globalization, economic competition, and extension of social services to general populations, all of which involve more and more people in continuous assistance and control of work processes over the 24 hours in a day. The large increase of epidemiological and clinical studies on this issue document the severity of this risk factor on human health and well being, at both social and psychophysical levels, starting from a disruption of biological circadian rhythms and sleep/wake cycle and ending in several psychosomatic troubles and disorders, likely also including cancer, and extending to impairment of performance efficiency as well as family and social life. Appropriate interventions on the organization of shift schedules according to ergonomic criteria and careful health surveillance and social support for shift workers are important preventive and corrective measures that allow people to keep working without significant health impairment.

• Journal of Korean Clinical Nursing Research
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• v.25 no.2
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• pp.107-119
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• 2019

Purpose: The purpose of this study was to investigate the welfare status of nurses and the status of fixed night shifts and flexible work arrangements in both general hospitals and advanced general hospitals in Korea. Methods: A total of 167 hospitals participated in this study, done from April to October 2018. Results: There were 103 hospitals utilizing the fixed night shift system, 22 in the two-shift system, 3 in the fixed holiday shift, 79 in the fixed shift system, and 39 in the short-time working system. The average welfare benefits for nurses increased to 33.02 million won on average. However, welfare services for the nurses were poor: 41.8% of the respondents had a nurses' lounge, 81.7% were given dormitory space at their place of employment, 41.8% had access to welfare facilities, and 56.4% were provided with welfare support countermeasures. Conclusion: The results show an increasing trend of hospitals to utilize fixed night shift and flexible work arrangements. An institutional strategy at the national policy level should be established to implement flexible work arrangements including the fixed night shift system, which has a poor level of welfare.

• Korean Journal of Adult Nursing
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• v.20 no.6
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• pp.941-949
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• 2008

Purpose: This study was conducted to describe the effects of aroma inhalation on sleep and fatigue in night shift nurses. Methods: The research design was one group pre-posttest design. The subjects were 17 night shift nurses who work at neurosurgery intensive care unit of K hospital of C university in Seoul. During three consequent night shifts, the participants were worn the Actigraph to measure the sleep pattern on their wrist since their first night shift work. The quality of sleep and fatigue was measured by survey when they awoke at 6 pm after second night shift work. And these measures were repeated during the night shifts in second and third week. Aroma inhalation was applied before going to bed after finishing each night shift work during second and third week. SPSS 12.0 program was used for data analysis. Results: There were no statistically significant differences in sleep latency and total sleeping time. However, significant differences were found in the sleep efficiency, awakening number, sleep quality, subjective symptom and intensity of fatigue. Conclusion: These results showed that aroma inhalation had positive effects on the pattern and quality of sleep and reducing fatigue in night shift nurses.

• Safety and Health at Work
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• v.6 no.3
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• pp.240-248
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• 2015

Background: Recovery from fatigue is important in maintaining night workers' health. This study compared the course of self-reported recovery after 2-week 12-hour schedules consisting of either night shifts or swing shifts (i.e., 7 night shifts followed by 7 day shifts) to such schedules consisting of only day work. Methods: Sixty-one male offshore employees-20 night workers, 16 swing shift workers, and 25 day workers-rated six questions on fatigue (sleep quality, feeling rested, physical and mental fatigue, and energy levels; scale 1-11) for 14 days after an offshore tour. After the two night-work schedules, differences on the $1^{st}$ day (main effects) and differences during the follow-up (interaction effects) were compared to day work with generalized estimating equations analysis. Results: After adjustment for confounders, significant main effects were found for sleep quality for night workers (1.41, 95% confidence interval 1.05-1.89) and swing shift workers (1.42, 95% confidence interval 1.03-1.94) when compared to day workers; their interaction terms were not statistically significant. For the remaining fatigue outcomes, no statistically significant main or interaction effects were found. Conclusion: After 2-week 12-hour night and swing shifts, only the course for sleep quality differed from that of day work. Sleep quality was poorer for night and swing shift workers on the $1^{st}$ day off and remained poorer for the 14-day follow-up. This showed that while working at night had no effect on feeling rested, tiredness, and energy levels, it had a relatively long-lasting effect on sleep quality.