• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.2
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• pp.318-327
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• 2002

In this paper, heat transfer and pressure oscillation characteristics on oscillating capillary tube heat pipe(OCHP) according to input heat flux, mixture ratio of working fluid and inclination angle were investigated and were compared single working fluid(R-142b) with binary mixture working fluid(R-142b-Ethano1). OCHP was made to serpentine structure of loop type with 10 turns by drilling the channels of length 220mm, width 1.5mm, and depth 1.5mm on the surface of brass plate. In this study, R-l42b and R-l42b-Ethanol were used as working fluids, the charging ratio of working fluids was 40(vol.%), the input heat flux to evaporating section was changed from 0.3W/㎠ to 1.8W/㎠, and mixture ratio of working fluid was R(100%), R(95%)-E(5%), R(90%)-E(10%), and R(85%)-E(15%). From the experimental results, it was found that the effective thermal conductivity of single working fluid was better than that of binary mixture working fluid. But, in case of binary mixture working fluid, critical heat flux was higher than that of single working fluid. And, the higher the mixture ratios of working fluid, the lower heat transfer performance. In case of pressure oscillation, as the inclination angle was lower, pressure wave was more irregular. These phenomena were more serious when the working fluid was binary mixture. Besides, when mixture ratio was higher, saturated pressure was increased, more irregular wave was observed and the mean amplitude was increased. For the same input heat flux, inclination angle and charging ratio, when pressure oscillation has sinusoidal wave, mean amplitude was small, and saturated pressure was low value, the heat transfer was excellent.

• 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.

• Journal of Mechanical Science and Technology
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• v.16 no.9
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• pp.1102-1111
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• 2002

The study focuses on the heat transfer performance of two-phase closed thermosyphons with plain copper tube and tubes having 50, 60, 70, 80, 90 internal grooves. Three different working fluids(distilled water, methanol, ethanol) are used with various volumetric liquid fill charge ratio from 10 to 40%. Additional experimental parameters such as operating temperature and inclination angle of zero to 90 degrees are used for the comparison of heat transfer performance of the thermosyphon. Condensation and boiling heat transfer coefficients, heat flux are obtained using experimental data for each case of specific parameter. The experimental results are assessed and compared with existing correlations. The results show that working fluids, liquid fill charge ratio, number of grooves and inclination angle are very important factors for the operation of thermosyphons. The relatively high rate of heat transfer is achieved when the thermosyphon with internal grooves is used compared to that with plain tube. The optimum liquid fill charge ratio for the best heat transfer performance lies between 25% and 30%. The range of the optimum inclination angle for this study is 20$^{\circ}$～30$^{\circ}$ from the horizontal position.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.9
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• pp.2314-2333
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• 2023

It is significant to predict the performance degradation of complex electromechanical systems. Among the existing performance degradation prediction models, belief rule base (BRB) is a model that deal with quantitative data and qualitative information with uncertainty. However, when analyzing dynamic systems where observable indicators change frequently over time and working conditions, the traditional belief rule base (BRB) can not adapt to frequent changes in working conditions, such as the prediction of aeroengine performance degradation considering working condition. For the sake of settling this problem, this paper puts forward a new hidden belief rule base (HBRB) prediction method, in which the performance of aeroengines is regarded as hidden behavior, and operating conditions are used as observable indicators of the HBRB model to describe the hidden behavior to solve the problem of performance degradation prediction under different times and operating conditions. The performance degradation prediction case study of turbofan aeroengine simulation experiments proves the advantages of HBRB model, and the results testify the effectiveness and practicability of this method. Furthermore, it is compared with other advanced forecasting methods. The results testify this model can generate better predictions in aspects of accuracy and interpretability.

• Wind and Structures
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• v.8 no.4
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• pp.235-250
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• 2005

The paper describes the work of the Working Group on Wind Structure, one of the International Codification Working Groups set up by the International Association of Wind Engineering in 1999. The topics of terrain and exposure, shielding and shelter, topographic effects, tropical cyclone and hurricane wind structure, and thunderstorm wind structure, are described with emphasis on their codification in wind loading codes and standards. Recommendations from the working group are given.

• Journal of Family Resource Management and Policy Review
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• v.6 no.2
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• pp.143-155
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• 2002

Nowadays, the conflict of work and family has become a common problem in families due to the increase of working parents. But in Korea, there is a little supporting system which can help them work. So, this study showed the necessity of family-friendly Policy and families' demands to it. Many capitalist countries which have insufficient welfare system effort to integrating work and family by offering a family-friendly policy for working parents. So, policies for family and women have to be family friendly, and all of the corporation, community, school, and government have to support the working families.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.18 no.1
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• pp.72-79
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• 2008

This study was surveyed to assess the status of safety accidents occurred in work-places and prepare the fundamental data and prevent the safety accidents. The authors reviewed and analysed the charts of accident cases treated at a primary care clinic in A city from January 1991 to December 2006. The data were classified according to the USA Standards Institute and International Labour Organization method. We analyzed the data using SPSS program. The results were as follows : 1. The total cases of accidents were 455 for 8 years. 2. Accidents were mostly common in the workers who are in thirties and forties age(84.4%). 3. As season variation, spring and summer were common than others, but there was no statistical significance on season, month and weekday. 4. The most frequent injured part of the body were hand and finger, which was 36.0% among total cases. 5. According to the accidents type, cases of caught in, under or between were most frequently observed as 53.9% of the total cases. 6. The most common source of injuries was power machine(50.5%). 7. According to the unsafe acts, cases of carelessness and unsafe information were most frequently observed as 71.2% of the total cases. 8. Admission rate(5.5%) and official report rate(2.2%) were very low rate. As above results, the authors recommend to prepare the systemic control programs on environmental and human factors of safety accidents such as improving the working conditions, working facilities, working methods and safety education, and control of working time for working day.

• Korean Journal of Health Education and Promotion
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• v.23 no.4
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• pp.105-124
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• 2006

Objectives: This study examined the reproductive health status and the work-related factors of female hairdressers. Methods: This study conducted by structured questionnaire from April 21th to May 20th. The study population of 316 were female hairdressers aged 15 to 60 years in Seoul. This study analysed the influencing factors, health related factors and work related factors on reproductive health using chi-square and multiple logistic regression analysis. Results: 1. The 81.7% of the subjects aged under 29 years have unhealthy behaviors. The 47% of hairdressers experienced smoking. Among the total, 37% of them answered they are smoking at present. Those results reveal their working conditions were very stressful to cope as young females. 2. The use of hair dyes(OR=2.89, 95%CI:1.17-7.12), counteractive solutions(OR=3.20, 95%CI:1.04-9.83) and not wearing protective gloves(OR=2.81, 95%CI:1.11-7.12) are significantly associated with menstrual pains. 3. The hairdressers not using perm liquids were three times as likely to report regular menstruation compared with the hairdressers using perm liquids. Wearing protective gloves also was associated with regular menstruation. Conclusion: This study revealed various risky working conditions of hairdressers was associated with their reproductive health. This study suggests that we should pay more attention to the protective working conditions for reproductive health. More comprehensive health management program including reproductive health for female hairdressers is required as well.

• The Journal of Korean Society for School & Community Health Education
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• v.15 no.1
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• pp.89-103
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• 2014

Objectives: The purpose of the study was to clarify the relationship between parenting, job related stress and child care using data from working mother's in Korea and Japan. Methods: In this study, we conducted a survey of 125 Korean mothers who used childcare facilities in two cities and 170 Japan mothers who used childcare facilities in two cities. The questionnaire sought information about the mother's age, age of the youngest child, family composition, mother's occupation, parenting stress, job stress, appropriate parenting behavior and child maltreatment. Based on this survey data, it was tried to reveal the effective paths between parenting stress, job stress, appropriate parenting behavior and child maltreatment in order to provide the rationale for intervention by using SEM. Results: Child care was statistically significantly affected by parenting stress and job stress for both Korean and Japanese working mother's. Conclusions: The results of the research suggest the need to establish work-life balance policies to improve the balanced lives of working mother's.

• Korea Journal of Hospital Management
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• v.23 no.4
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• pp.65-80
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• 2018

Purposes: The purpose of this study was to analyze the relationship between empowerment, job satisfaction and organizational commitment of the general hospital administrative staff working for customer interaction department. Methodology: For this purpose, this study sampled 260 administrative staff working for the general hospitals in Seoul and Gyeonggi-do. A total of 260 questionnaires were distributed to them, and 229 ones responded to the survey, which had been conducted from Mar. 9, through Mar. 30, 2018. 211 responses were used for the final analysis. The data collected were processed using the SPSS 18.0K for descriptive statistics, T-test, ANOVA and regression analysis. Findings: The results of this study can be summed up as follows. The empowerment of the subjects scored 3.73 on average on the 5-point scale. To be specific, the sub-factor 'meaning' scored the highest or 4.01, while the sub-factor 'impact' was lowest. Subjects' job satisfaction scored 3.37 and their organizational commitment scored 3.54 both on the 5-point scales. Practical Implications: Meaning and self determination of empowerment positively related to subjects' job satisfaction and organizational commitment, and particularly, meaning of empowerment was more strongly related. Hence, it is required of the general hospitals to operate a customized competence build-up program and educational courses on a continual basis. Besides, it would also be important to create a working environment wherein the administrative staff can demonstrate their deliberation, autonomy and independent services.