• 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.

• Korean Journal of Labor Studies
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• v.17 no.1
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• pp.37-70
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• 2011

The 40-hour work week system has brought positive impact on shortening working hours, eliminating long-time work, increasing leisure-time with family, etc. And this has brought about an increase in leisure-life satisfaction and happiness level. The type of leisure activities has changed from passive activities such as rest to active activities such as sports, tourism. And the 40-hour work week system has positive impact on social activities such as participation in volunteer work and, club activities. Thus all efforts need to be made to establish 40-hour work week system as soon as possible in all workplace. Firstly, 40-hour work week system needs to be introduced to every workplace with less than 5 persons, enlarge 5-day school week system into every primary and secondary school, and create conditions for positive leisure activities. Secondly, labor standards supervision and administration needs to be strengthened to eliminate long-time work over 52 hours per week, below-minimum wage work.

• Safety and Health at Work
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• v.6 no.2
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• pp.104-113
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• 2015

Background: Given the long hours on the road involving multiple and interacting work stressors (i.e., delivery pressures, irregular shifts, ergonomic hazards), commercial drivers face a plethora of health and safety risks. Researchers goal was to determine whether and to what extent long-haul trucker work schedules influence sleep duration and quality. Methods: Survey and biometric data collected from male long-haul truck drivers at a major truckstop in central North Carolina over a six month period. Results: Daily hours worked (mean = 11 hours, 55 minutes) and frequency of working over government-mandated daily HOS regulations (23.8% "frequently or always") were statistically significant predictors of sleep duration. Miles driven per week (mean = 2,812.61), irregular daily hours worked (63.8%), and frequency of working over the daily hour limit (23.8% "frequently or always") were statistically significant predictors of sleep quality. Conclusion: Implications of findings suggest a comprehensive review of the regulations and operational conditions for commercial motor vehicle drivers be undertaken.

• Korean Journal of Biological Psychiatry
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• v.29 no.2
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• pp.46-55
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• 2022

Objectives Many studies have reported noticeable increases in the proportion of employees working either relatively short or relatively long hours. Such trends have been accompanied by an increasing concern that how much subjective mental well-being of employees would be influenced by their hours of work. The aim of this study was to investigate the association between work hours and clinically relevant depressive symptoms with demographic variables adjusted. Methods Participants were employees of a total of 56 private companies and local government organizations in Korea, aged 19 to 65 years. A self-report questionnaire that included items on working hour, job stress, levels of depression, and socio-demographic factors was administered to 15360 Korean employees, with 14477 valid responses. Hierarchical linear regression analyses, adjusted for sociodemographic factors, job related demographic factors, job stress, were used additionally to estimate the association between working hours and depressive scores. Results We found that working more than 40 hours per week correlated positively with the level of depressive symptoms after adjusting for demographic variables and the level of job stress. Furthermore, working 40 or fewer hours per week correlated negatively with the level of depressive symptoms. Being younger (β = -0.078, β = -0.099), being a female (β = 2.770, β = 1.268), and possessing a lower level of education (β = -0.315, β = -1.125) were significantly associated with higher level of depressive symptoms in all respondents. Conclusions Both of working excessively long or short hours is significantly associated with the prevalence of depressive symptoms. Establishing proper office hours for employees is critical to improving the quality of working conditions and maintaining good mental health in the workplace.

• Solar Energy
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• v.18 no.4
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• pp.101-110
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• 1998

The purpose of this research is to study the charateristics and manufacture of a composite heat pipe system with rotational and static pipe. A composite heat pipe system were tested to obtain the relationship between the expansion injector and auxiliary expansion for the motion of the working fluid by the experimental results. In addition the heat transport characteristics were found based on wall temperature of rotor, expansion injector, storage tank and vapor temperature. Water is used as working fluid of heat pipes. As the results of experiments, the composite heat pipe was operated for long times, 10 hour above with various rotational speed in performance. There were a few unexpected data by the capillary pumped loop at small working fluid, but as a whole the testing was successful.

• Journal of Venture Innovation
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• v.4 no.2
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• pp.97-108
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• 2021

Labor contracts appear in form as an exchange relationship between labor products and wages, but since they transcend the level of simple barter, they can be economically identified as "trading" and can be identified as "rental." From a legal point of view, a legal device that legally supports and imposes binding force on commodity exchange relations is a contract. Such a labor contract led to a relationship in which wages were received and a certain amount of time was placed under the direction and supervision of the employer as a counter benefit to the receipt of wages. Since working hours are subordinate hours with one's labor under the disposition authority of the employer, long hours of work can be done for the health and safety of workers and furthermore, it can be an act that violates the value to enjoy as a human being. The reduction of working hours needs to be shortened in terms of productivity and enjoyment of workers' culture so that they can expand and reproduce, but users' corporate management labor and production activities should also be compatible compared to those pursued by capitalist countries. Working hours can be seen as individual time and time in society as a whole, and long hours of work at the individual level are reduced, which is undesirable at the individual level, but an increase in products due to an increase in production time at the social level can help social development. It is necessary to consider working hours in terms of finding the balance between these individual and social levels. If the regulation method of working hours was to regulate the total amount of working hours, flexibility and elasticity of working hours are a qualitative regulation method that allows companies to flexibly allocate and organize working hours within a certain range of up to 52 hours per week. Accordingly, it is necessary to shorten working hours, but expand and implement the flexible working hours system according to the situation of the company. To this end, it is necessary to flexibly operate the flexible working hours system, which is currently limited to six months, handle the selective working hours by agreement between employers and workers, and expand the target work of discretionary working hours according to the development of information and communication technology and new types based on the 4th industrial revolution.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.29 no.3
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• pp.383-393
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• 2019

Objectives: The proportion of those working beyond 53 hours a week in 2018 has reached 16.8% of the total number of workers in the Republic of Korea (Statistics Korea, 2018). Although there are many studies that have dealt with the correlation of long working hours and increasing risk of work-related health problems, studies dealing with the factors impacting work-related health problems of workers according to their working hours are few. This study aims to ascertain factors impacting work-related health problems of workers based on their working hours through thorough research on their work environment. Methods: Necessary factors for this study were extracted from 'the 4th Korean Working Conditions Survey to analyze details on normal characteristics and work environments used for the study analysis, work hours, and health problems related to work. Results: The results are as follows: First, men showed a greater probability of exposure to work-related health problems than did women, especially in the 50s age group, which showed the highest potential for health problems from work among age groups. Second, service providers and sales professionals showed a higher probability of work-related health problems. Third, for the work environment, health problems at work related to vibration, noise, chemical and poison exposure, exhaustion, pain, standing position, and repeated motion showed a higher probability if the work hours are long. Conclusions: This study suggests that the minimization of overtime labor would prevent work-related health problems and diseases, improve the well-being of workers, and decrease the negative impact on workers in the subject area.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.375-375
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• 2006

The preparation methods are to be used as "melting method" and "absorption method", respectively. The reaction mixture in the reaction container was heating up the reaction mixture to $200^{\circ}C$ for 2 hour. The mixing time of lab scale preparation should be provided quit long, instead of the short working time in a compounder vessel. And The PP-PCM mixture in the reaction container was heating up the mixture around $60-80^{\circ}C$ for 2 hour. A melting method of frozen gel with 50/50 weight ratio of polypropylene-normal octadecane was prepared by adding PP chip and normal octadecane. An absorption method of frozen gel with 70/30 weight ratio of PP 4.8-normal n-octadecane was prepared by adding PP powder and normal octadecnae.

• Journal of Chest Surgery
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• v.27 no.9
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• pp.723-731
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• 1994

We have modified the isolated perfused working rabbit lung model [IPWL] by perfusing the isolated lung with a hollow fiber membrane deoxygenator.For assessment the stored lung was ventilated with FIO2 0.4 and perfused with 37$^{\circ}$C deoxygenated circulating blood at a rate 5ml/kg/min for several hours until lung failure.We chose to compare our developing solution which contained low potassium and pentastarch with the modified Euro-Collins solution .Experiments were divided into four groups[n=6] based on the type of flushing preservation solution and preservation time.The flushed lungs were then preserved into same solution at 8~10$^{\circ}$C with 100% O2 inflated condition for 1 or 20 hours.These following results were obtained.The IPWL model requires only one animal per experiment and allows for the continuous assessment of aerodynamic performance. This should therefore be used as screening test in lung preservation.One hour preservation groups, there were no significant difference in recovery rates of PaO2, PAP and Paw. Survival time in the one hour preservation groups were very significant long in the Group II[LPPS, p<0.01]. Twenty hours preservation groups, there were no significant difference in the recovery rates of PAP and Paw between Group III[m-ECS] and Group IV[NS], but PaO2 was significantly worse at onset of reperfusion in Group III when compared with Group IV [p<0.05]. And also survival time in the 20 hours preservation groups were significant long in the Group IV [p<0.05].

• Journal of the Korean Home Economics Association
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• v.31 no.3
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• pp.101-112
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• 1993

The purpose of this study is to examine the real life of married women employed in a manufacturing industry by analysis patterns of their time use. Data for 172 married working women were gathered from the use of face-to-face interview method. The results were shown as follows; 1) Married female production workers spend 8 hours 44 minutes a weekday, and 10 hours 39 minutes a Sunday on physiological activities, and on socio-cultural activities 1 hour 50 minutes(weekday), 5 hours 30 minutes (sunday). 10 hours 22 minutes, 2 hours 23 minutes were consumed for the employed time compared to 3 hours 4 minutes, 5 hours 28 minutes for household labor. 2) Married working women's employed labor time is excessively too long while for leisure and house work time is too short, which means the patterns of their time use are very unbalanced type.