• Annals of Occupational and Environmental Medicine
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• v.35
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• pp.21.1-21.11
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• 2023

Background: Recently, irregular working hours have become controversial issues in Korea. The health impact of irregular working hours on the work-related musculoskeletal pain (MSP) is scarcely researched before. We sought to investigate the association between irregular working hours and work-related MSP among South Korean workers. Methods: This study used data from the sixth Korean Working Conditions Survey in 2020. The prevalence of work-related MSP was analyzed using the χ² test. A multiple logistic regression analysis was conducted to assess the association between irregular working hours and work-related MSP. We conducted stratified analysis by gender, weekly working hours, and workers' control over their working hours. We calculated the adjusted odds ratios (ORs) of work-related MSP for irregular working hours combined with weekly working hours. Results: The OR for work-related MSP was significantly higher in the population with irregular working hours than in the population with regular working hours (OR: 1.43, 95% confidence interval [CI]: 1.29-1.58). Irregular and long (> 52 hours/week) working hours have the highest risk of work-related MSP in both genders (in men, OR: 3.48 [95% CI: 2.53-4.78]; in women, OR: 2.41 [95% CI: 1.46-4.00]). Conclusions: Irregular working hours were associated with work-related MSP in Korea. The association was magnified with long working hours. Reform of the Korean Labor Standards Act leading to increase irregular working hours may induce adverse health outcome.

• Journal of the Korean Society of Food Culture
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• v.35 no.4
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• pp.323-332
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• 2020

This study examined Korean employees' meal structure characterized by mealtime, meal places, and companions. The data from 19,692 time diaries, recorded by 9,846 employees aged 19-64 years for two days in the 2014 Korean Time Use Survey, were analyzed for working days and non-working days. Approximately two-thirds of Korean employees ate meals three times a day on both working and non-working days. The breakfast and lunch-times on working days were distributed within two hours, but the dinner time on working days and all three meals on non-working days were dispersed across a three-hour range. Male employees spent three minutes on meal preparation on working days, whereas females spent 30 minutes. On working days, 88% of breakfasts and 67% of dinners were eaten at home. For lunches, 46% were eaten at restaurants, and 42% were at workplaces. The breakfast on working days showed the highest percentage of eating alone (40%) and the dinner on non-working days appeared highest in the percentage of eating with families (69%). The characteristics of Korean employees' meal structure appeared different on working days and non-working days. Such characteristics should be considered in the process of planning nutrition policies and programs for employees.

• Annals of Occupational and Environmental Medicine
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• v.35
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• pp.8.1-8.12
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• 2023

Background: Prolonged use of visual display terminal (VDT) can cause eyestrain, dry eyes, blurred vision, double vision, headache and musculoskeletal symptoms (neck, shoulder, and wrist pain). VDT working hours among workers have greatly increased during the coronavirus disease 2019 (COVID-19) pandemic. Therefore, this study aimed to investigate the relationship between VDT working hours and headache/eyestrain in wage workers using data from the sixth Korean Working Conditions Survey (KWCS) (2020-2021) conducted during the COVID-19 pandemic. Methods: We analyzed the sixth KWCS data of 28,442 wage workers aged 15 years or older. The headache/eyestrain that occurred in the last year was assessed. The VDT work group included workers who use VDT always, almost always, and three-fourth of the working hours, while the non-VDT work group included workers who use VDT half of the working hours, one-fourth of the working hours, almost never, and never. To analyze the relationship between VDT working hours and headache/eyestrain, the odds ratios (ORs) and 95% confidence interval (CI) were calculated using logistic regression analysis. Results: Among the non-VDT work group, 14.4% workers experienced headache/eyestrain, whereas 27.5% workers of the VDT work group experienced these symptoms. For headache/eyestrain, the VDT work group showed adjusted OR of 1.94 (95% CI: 1.80-2.09), compared with the non-VDT work group, and the group that always used VDT showed adjusted OR of 2.54 (95% CI: 2.26-2.86), compared with the group that never used VDT. Conclusions: This study suggests that during the COVID-19 pandemic, as VDT working hours increased, the risk of headache/eyestrain increased for Korean wage workers.

• Safety and Health at Work
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• v.15 no.1
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• pp.102-109
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• 2024

Background: In today's modern world, longer working hours, shift work, and working at night have become major causes of the disruption of our natural circadian rhythms. This study aimed to investigate the effects of the type of shift work (rotating vs. fixed day), duty period (on-duty vs. off-duty), and working period within each shift (nighttime vs. daytime) on the circadian rhythm characteristics of nurses who provide direct patient care. Methods: This cross-sectional study used a purposive sampling method. Cosinor analysis was applied to analyze the actigraphy data of nurses providing direct patient care for seven consecutive days. The linear mixed effects model was then used to determine any variances between shift type, duty period, and working period within each shift for the nurses. Results: The mesor value did not differ according to nurses' shift type, duty period, and working period within each shift. The amplitude was statistically higher in on-duty nurses and in daytime working hours. The acrophase was significantly delayed in nighttime working hours. As well as nurses in rotating shift had experience. Conclusion: Our findings revealed that the peak activity of nurses occurs significantly later at night while working and nurses working during nighttime hours may have a weaker or less distinct circadian rhythm. Thus, this study suggests that limits be placed on the number of rotating nighttime shifts for nurses.

• Safety and Health at Work
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• v.15 no.1
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• pp.73-79
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• 2024

Background: This study aimed to investigate the relationship between work-related communication devices use during work outside of regular working hours and depressive symptoms in wage workers. Methods: Data from 50,538 workers aged 15 years or older who had participated in the 6th Korean Working Condition Survey (KWCS) were used. The final sample was 32,994 wage workers. The questionnaire asked the respondents how often they used communication devices for work during work outside of regular working hours. Depressive symptoms were assessed using WHO-5 Well-Being Index. Multiple logistic regression analysis was used to analyze the association between work-related communication devices use during work outside of regular working hours and depressive symptoms. Results: The rate of depressive symptoms was highest among workers who did not use work-related communication devices during work outside of regular working hours. After adjusting for socio-demographic and work-related factors, the odds ratio of depressive symptoms among workers who used communication devices when working outside of regular working hours was 1.20 (95% CI: 1.09-1.32); the odds ratio of depressive symptoms in the group not using communication devices for free-time work was 1.66 (95% CI: 1.37-2.00), which was higher than that of the reference group, that is, workers who did not work outside of regular working hours, and was statistically significant. Conclusion: Regardless of whether work-related communication devices are used, working outside of regular working hours increases depressive symptoms. The use of work-related communication devices during work outside of regular working hours can reduce the rate of depressive symptoms.

• Safety and Health at Work
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• v.8 no.4
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• pp.343-346
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• 2017

Background: Long working hours adversely affect worker safety and health. In 2004, Korea passed legislation that limited the work week to 40 hours, in an effort to improve quality-of-life and increase business competitiveness. This regulation was implemented in stages, first for large businesses and then for small businesses, from 2004 to 2011. We previously reported that average weekly working hours decreased from 2006 to 2010, based on the Korean Working Conditions Survey. Methods: In the present study, we examine whether average weekly working hours continued to decrease in 2014 based on the 2014 Korean Working Conditions Survey. Results: The results show that average weekly working hours among all groups of workers decreased in 2014 relative to previous years; however, self-employed individuals and employers (who are not covered by the new legislation) in the specific service sectors worked > 60 h/wk in 2014. Conclusion: The Korean government should prohibit employees from working excessive hours and should also attempt to achieve social and public consensus regarding work time reduction to improve the safety, health, and quality-of-life of all citizens, including those who are employers and self-employed.

• Korean Journal of Radiology
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• v.1 no.1
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• pp.19-24
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• 2000

Objective: In order to investigate the functional brain anatomy associated with verbal and visual working memory, functional magnetic resonance imaging was performed. Materials and Methods: In ten normal right handed subjects, functional MR images were obtained using a 1.5-T MR scanner and the EPI BOLD technique. An item recognition task was used for stimulation, and during the activation period of the verbal working memory task, consonant letters were used. During the activation period of the visual working memory task, symbols or diagrams were employed instead of letters. For the post-processing of images, the SPM program was used, with the threshold of significance set at p < .001. We assessed activated brain areas during the two stimulation tasks and compared the activated regions between the two tasks. Results: The prefrontal cortex and secondary visual cortex were activated bilaterally by both verbal and visual working memory tasks, and the patterns of activated signals were similar in both tasks. The superior parietal cortex was also activated by both tasks, with lateralization to the left in the verbal task, and bilaterally without lateralization in the visual task. The inferior frontal cortex, inferior parietal cortex and temporal gyrus were activated exclusively by the verbal working memory task, predominantly in the left hemisphere. Conclusion: The prefrontal cortex is activated by two stimulation tasks, and this is related to the function of the central executive. The language areas activated by the verbal working memory task may be a function of the phonological loop. Bilateral prefrontal and superior parietal cortices activated by the visual working memory task may be related to the visual maintenance of objects, representing visual working memory.

• Journal of Drive and Control
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• v.13 no.4
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• pp.14-22
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• 2016

This paper presents a stochastic and predictive working-risk-assessment algorithm for excavators based on a one-layer laser scanner. The one-layer laser scanner is employed to detect objects and to estimate an object's dynamic behaviors such as the position, velocity, heading angle, and heading rate. To estimate the state variables, extended and linear Kalman filters are applied in consideration of laser-scanner information as the measurements. The excavator's working area is derived based on a kinematic analysis of the excavator's working parts. With the estimated dynamic behaviors and the kinematic analysis of the excavator's working parts, an object's behavior and the excavator's working area such as the maximum, actual, and predicted areas are computed for a working risk assessment. The four working-risk levels are defined using the predicted behavior and the working area, and the intersection-area-based quantitative-risk level has been computed. An actual test-data-based performance evaluation of the designed stochastic and predictive risk-assessment algorithm is conducted using a typical working scenario. The results show that the algorithm can evaluate the working-risk levels of the excavator during its operation.

• Anxiety and mood
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• v.18 no.1
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• pp.32-37
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• 2022

Objective : Impaired working memory has been known to play an important role in the pathophysiology of obsessive-compulsive disorder (OCD) with growing evidence. Delayed matching-to-sample task (DMST) is a working memory task which have an advantage in analyzing several different working memory processes in one task. However, most of the studies have failed to reveal the working memory impairment with the DMST. The aim of this study was to identify whether working memory deficit in OCD can be evaluated with the DMST. Methods : The participants included 20 OCD patients and 20 healthy volunteers. Working memory was evaluated with the DMST with two different working memory loads. Accuracy of response and mean response time were measured. Results : OCD patients showed a significantly longer reaction time and lower accuracy in DMST compared to healthy controls in the task with high working memory loads. Moreover, the difference in accuracy showed interaction with the working memory load. Conclusion : The present results indicate that working memory deficit in patients with OCD can be evaluated with the DMST. The findings also suggest that previous negative behavioral results using the DMST were from low working memory load of the task.

• Korean Journal of Biological Psychiatry
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• v.16 no.4
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• pp.238-245
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• 2009

Objectives : Mild Alzheimer's disease(AD) is uncertain to be related to visuospatial working memory subsystem dysfunction. We used the self ordered pointing test(SOPT) to find the characteristics of visuospatial working memory in mild AD. Methods : We compared the visuospatial working memory abilities of 20 patients with mild AD and 20 normal elderly controls(NC) using SOPT, of which stimuli consisted of two stimuli types(A : abstract, C : concrete) and two stimuli numbers(8 and 12). Therefore, working memory was tested using C8, C12, A8, and A12 stimuli conditions in SOPT. Mixed-model ANOVA was conducted with the AD and NC groups as between-subjects factor, with stimuli types and stimuli numbers as the within-subjects factors and with SOPT error rates as the dependent variable. Results : The AD group showed higher error rates in SOPT than the NC group. The NC group showed low error rates in concrete stimuli than in abstract stimuli and in small stimuli numbers than in large stimuli numbers. And the AD group showed no differences between stimuli types or stimuli numbers. Conclusion : AD patients showed a poor performance in visuospatial working memory using concrete stimuli. The result suggests that there is a non-transformation from visual input to phonological working memory in AD. Patients with AD showed a poor performance although in small stimuli number condition of SOPT. It suggests that in AD, visuospatial working memory is not working well although in low central executive loads.