• 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 the Korean Society of Costume
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• v.41
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• pp.185-206
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• 1998

The purpose of this study was to improve productivity for maximum effects with the present equipments and staff. This study compared and analyzed the mea-sured time by using stop watch method and MTM, which was the new measuring method. The flow and results of this study were as follows: 1. This study investigated the theoretical background the efficiency for production management, and the way of productivity improvement through documentary research. 2. Setting up the standard flow on the experi-mental company production, making out a process chart and measuring the actual working hour. 3. The study measured the allowance time applying work sampling. 4. Each process of the movement analysis was filmed by video to use basic data. 5. MTM analysis was taken by choosing 10 processes from front bodice according to the basic movement of MTM. Through the results, this study exclude unneccesary movements and suggest a method for working ways. 6. Using the actual working hour measured by a stop watch calculated the pitch time and presumed the amount of daily productivity. 7. The result of the work sampling came out as 38% of allowance rate. It was 13% higher than the standard amount of woman's jacket allowance rate, which was 25%. The most influencing factor was work discussion. That was because there were commuication problem of the work way between the operator and leader. More adequate use of flow table and level passing table was needed. There were the problems that inappropriate places and sizes made the distance of movements longer and often needed more adjustment of works and surroundings. To prevent breakdowns equipments check ups were necessary before works. 8. The results of MTM analysis were as follow : the time was reduced 40% than the actual measured time by a stop watch. This was because the leveling of the operator was included in the real calculation. Also, leveling was included in MTM analysis and all the conditions were standarized. Therefore MTM method was a scientidic measuring way of establishing the standard time. The presented method of this study, suggested an ideal method eliminating unneccesary motions, and presented standardization of works. Improvement of working methods, work condition and simplifying motions in each 10 processes reduced the working time from total 656 seconds to 301 seconds. 9. The way and time of working was linked together in the MTM analysis methods. Thus data from MTM help suggest not only establishing standard time but also establishing stan-dard work. Plus it includes various ability for improvements of working ways. So it is an objective method which can be widely used in other work studies. 10. The function of a time study is to determine the amount of work produced with a given method. The work rate is used to establish the cost of labor. The wage of worker must be calculated per unit time which is deter-mined before the time study is made. This study tried to introduce the incentive rule for deciding wages according to the standard time by MTM method.

• 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.

• Particle and aerosol research
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• v.12 no.4
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• pp.161-168
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• 2016

The purpose of this study is to determine the performance characteristics of the paint particulate and volatile organic compounds(VOCs) simultaneous removal from the spraying paint booth in the laboratory and real site by sticky paint particulate and VOCs simultaneous removal demonstration unit. The sticky paint particulate and VOCs simultaneous removal unit is composed of the horizontal type pleated filter modules and the zig-zag type granular activated carbon packing modules. The test conditions at the laboratory are $50.15g/m^3$ of average paint aerosol concentration and 300 ppm of VOCs concentration which were same as the working conditions of spraying paint booth in the real site. But, the demonstration conditions at the real site are varied according to the working condition of spraying paint booth for the kind of passenger car bodies. The test results at the laboratory obtained that 99% of total particulate collection efficiency at 0.62 m/min of filtration velocity and 84% at 1.77 m/min of filtration velocity. The VOCs removal efficiencies are 97% at $3500hr^{-1}$ of gas hour space velocity and 59% at $10,000hr^{-1}$ of gas hour space velocity. In the real site test, the average removal efficiency of PM10 was measured to be 99.65%, the average removal efficiency of PM2.5 was 99.38%, the average removal efficiency of PM1 was 98.52%, and the average removal efficiency of VOCs was 89%.

• Journal of Technologic Dentistry
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• v.32 no.3
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• pp.211-220
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• 2010

Purpose: The purpose of this study was to analyze dental laboratory's working environment and turnover intention level and to examine its correlation. Methods: 180 dental technicians in Seoul, Incheon, and Chungnam area were selected. Survey was carried out from April 6, 2009 to May 20, 2009 by using self-administered questionnaire. As for the tools for this study, the structured questionnaire was used with its proven reliability and feasibility, and the contents of questionnaire consisted of 43 questions on the basis of related references. The questionnaire consisted of total 32 questions which included general attribute of subjects(14 questions), working Environment(20 questions) and turnover intention(9 questions). The data analysis was processed by computerized system with SPSS 12.0. Statistical analysis techniques included frequency, percentage, T-test, F-test analysis and regression analysis. Results: As a result of analyzing the research subjects' working environment level, there was significant difference in the item of health(P<0.05). The average in the working environment was indicated to be high with 1.53. As a result of analyzing the research subjects' turnover intention level, there was difference in the item of working hours a day(Hour), job satisfaction level, plan for task continuity, most difficulty given task(P<0.05). The average of turnover intention was indicated to be high with 2.85. Conclusion: Correlation between working environment and turnover intention, most of variables were indicated to have reverse correlation, thereby having been shown that the worse working environment leads to the more turnover intention.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.27 no.5
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• pp.358-363
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• 2015

As a preparation process for successful establishment of demonstration offshore wind farm, analyses have been made for working time at the construction site where working time is defined as the time available for marine operation to take place under given weather conditions. Data used are hourly wave and wind data from met mast, HeMOSU-1, and 3 hour numerical model data from Korea Meteorological Administration (KMA). Seasonal results show the minimum working time during winter and moderate during autumn and spring. The most working time was seen during summer on average. Monthly analyses show the most working time in May, June, and August which was higher than the working time in July and September. Working time reaches at steady state and no significant change was seen above wave height of 1.5 m and wind speed of 8 m/s.

• Safety and Health at Work
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• v.12 no.4
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• pp.517-521
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• 2021

Background: This study aimed to investigate whether working long hours was related to infertility among female Korean workers, while taking age into consideration. Methods: We used data from the 2018 National Survey on Fertility and Family Health and Welfare in Korea that is a cross-sectional, nationally representative, and population-based survey. Infertility was defined as women who were not pregnant after regular unprotected intercourse for a year. Working long hours was classified as ≥52 hours, and subgroups as per age were classified on the basis of being younger or older than 40 years of age. Differences in infertility risk between the long working hour group and none were estimated in crude and fully adjusted logistic regression models with age-group stratification. Results: Of 5,909 Korean female workers, the crude and adjusted odds ratios (95% confidence intervals) of infertility for working long hours were 1.295 (0.948-1.737) and 1.303 (0.921-1.809), respectively. In the subgroup of patients below 40 years of age, the crude and adjusted odds ratios (95% confidence interval) were 1.957 (1.216-3.039) and 1.921 (1.144-3.120), whereas those aged 40 years or older had 0.994 (0.647-1.471) and 0.939 (0.560-1.501), respectively. The weighted prevalence of infertility increased as weekly working hours increased only for the younger than 40-year subgroup. Conclusions: Infertility is associated with working long hours, especially in young-aged workers. Thus, the working schedule must be structured to better suit young female workers.

• Journal of Preventive Medicine and Public Health
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• v.26 no.1 s.41
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• pp.37-48
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• 1993

This study was conducted to investigate the prevalence rate of low back pain during past one year and its risk factors. The data were collected from 1,384 manufacturing factory workers from March 1, 1992 to August 30, 1992. The results obtained were as follows: 1. The one year prevalence rate of low back pain by manufacturing company was 38.4% in textile manufacturing, 35.2% in concrete reenforcement, 31.0% in cigarette and 26.1% in metal part(P<0.01). 2. In textile manufacturing, age groups with high prevalence rate of low back pain were 30's(36.8%) and 40's(36.4%) (P<0.05), and the one year prevelence rates of low back pain by marital state were 34.9% in married workers and 28.5% in unmarried(P=0.0511). 3. The one year prevelence rates of low back pain by job part are 35.0% in labor workers and 26.1% in clerical(P<0.05), and by work hour per day it was 34.9% in 9 or more and 28.9% in 8 or less(P<0.05). 4. The highest group of low back pain by work posture was 43.5% in 'lifting and transfering materials', and it by fitness of chair was 56.0% in uncomfortable one, and by height of working board was 33.6% in low working one. 5. In logistic regression analysis, significant determinants with low back pain were marital state(p<0.05), work hour per day(P<0.05), height of working board(P<0.01), and work posture(P<0.01).

• Korean Journal of Labor Studies
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• v.17 no.1
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• pp.269-295
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• 2011

This paper is about the part-time work and related polices in Netherland, which increased the employment rate for the past 30 years with part-time job creation. Netherland has been successful in making part-time 'good' jobs. There were many factors which contributed to increaing part-time jobs such as market, institution, policies, and industrial relations. There was virtuous cycle between increase in the supply of female labor power and increase in the demand for part-time worker in the labor market. The policies were reinforced which protect part-time workers, introduced the incentive system which was favorable to part-time wokres, guaranteed the right to select working hours to workers. Particularly, the labor market, institutions and policies were created in the midst of the social dialogue. As the polder model has been persisted for almost 30 years, the switch to full-time work or long working-hour model would not be possible. As the poler model is a very specific model based on the Netherland's own social conditions, it is not easy to copy and transplant in other countries.

• Journal of Preventive Medicine and Public Health
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• v.10 no.1
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• pp.34-43
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• 1977

This study attempts to examine the performances of Myun Health Workers-the frontline workers in the Korean rural health care delivery system. The time-activity approach was mainly utilized as a measuring tool. This study was undertaken in September 1976 with 35 Myun Health Workers at the Kang Wha County. The pretested time-activity approach sheets were filled out daily for one month by those Myun Health Workers themselves. Statistical means and variances of analysis were utilized for statistical method in comparing some activities and functions converged into time distribution Findings: 1. The workers's average working hours derived in this study is 8 hours and 48 minutes per day, which takes half an hour longer than normal schedule. 2. They spend 56% working hour for direct services, in other words, the main function, 22% for supportive function, and 22% for other activities, the unrelated health services. 3. Considering the total working hours of main function, out-center activity is far more than in-center services with the ratio of 70% to 30% respectively, which proves, therefore, that the main activity of the workers is home visiting. 4. It takes 20 minutes purely for home visiting and takes 14 minutes for transportation. 5. This research also indicates that such factors as characteristics of the health workers and myun influence in shaping the structures of the worker's function and activity: a. The workers whose working site is located in myun office spend 15% among total working hours in carring out official myun activities, which is incidentally unrelated to health services, while the health subcenter have no rooms for administrative jobs for myun office. b. The workers whose office is in health subcenter contribute much time in doing main function and those working in special project distribute more time in performing supportive function. c. The types of workers are another dominant factor to influence the components of worker's functions and activities. MCH workers and MPW I spend much time for manipulating main function. d. MPW II, whose function is reorganized by special project in 2 myuns shows different pattern of time distribution compared to the TB worker orFP worker in the ordinary area. MPW II distributes their time evenly in performing MCH program, T.B. Program, F.P. program and education activity, while the unipurpose workers engage in carring out only their dominant role. e. Another variables which involve the variation of the worker's activity can be illustrated with the variables like target population, size of myun and convenience for transportation, among which the latter two are remarkable factors in determining the time for out-center service.