• 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.

• International Journal of Fluid Machinery and Systems
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• v.9 no.3
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• pp.265-276
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• 2016

Energy systems working coherently in different conditions may not have a specific design which can provide optimal performance. A system working for a longer period at lower efficiency implies higher energy consumption. In this effort, a methodology demonstrated by a jet pump design and optimization via numerical modeling for fluid dynamics and implementation of an evolutionary algorithm for the optimization shows a reduction in computational costs. The jet pump inherently has a low efficiency because of improper mixing of primary and secondary fluids, and multiple momentum and energy transfer phenomena associated with it. The high fidelity solutions were obtained through a validated numerical model to construct an approximate function through surrogate analysis. Pareto-optimal solutions for two objective functions, i.e., secondary fluid pressure head and primary fluid pressure-drop, were generated through a multi-objective genetic algorithm. For the jet pump geometry, a design space of several design variables was discretized using the Latin hypercube sampling method for the optimization. The performance analysis of the surrogate models shows that the combined surrogates perform better than a single surrogate and the optimized jet pump shows a higher performance. The approach can be implemented in other energy systems to find a better design.

• Journal of Korean Academy of Nursing Administration
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• v.18 no.3
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• pp.320-328
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• 2012

Purpose: Professional quality of life is the quality one feels in relation to their work as a helper. The purpose of this study was to describe professional quality of life among emergency nurses. Methods: A total of 15 emergency rooms were selected in three cities. Among 263 nurses working at these emergency rooms, 178 nurses consented to participate in this cross-sectional survey. Professional Quality of Life (ProQOL) Scale version 5 was used to measure compassion satisfaction, burnout and secondary traumatic stress. Cluster analysis was used to classify nurses according to professional quality of life. Results: The mean scores (SD) for compassion satisfaction, burnout, and secondary traumatic stress were 32.12 (5.45), 28.27 (4.28), and 28.20 (5.07), respectively. The result of cluster analysis according to standardized score of compassion satisfaction, burnout, and secondary traumatic stress yielded three clusters. Over 50% of participants showed low professional quality of life. Nurses who were included in a cluster representing low professional quality of life were younger, had shorter periods of nursing experience, and perceivedlower social support than other cluster. Conclusion: Education or support programs for emergency nurses are needed to enhance their professional quality of life.

• 대한공업교육학회지
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• v.42 no.2
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• pp.1-19
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• 2017

The purpose of this study is to analyze the job performance hours and reasonable job performance hours of teachers working at secondary level technical vocational education institutes. This study analyzed the differences in the job performance hours and reasonable hours that have been investigated according to special subject teachers and general subject teachers. Based on Job Specifications of Teachers Working at Secondary Level Technical Vocational Education Institutes, the development of research tool was finalized, and questionnaires were used as the research tool. The results of this study are as follows. First, the total job performance hours and total reasonable job performance hours perceived by teachers working at secondary level technical vocational education institutes were found to be 2,787.8 minutes and 2,934.7 minutes respectively with a difference of 146.9 minutes. In regards to the job category-specific job performance hours, they were found to be high in the order of lesson administration, extracurricular student guidance, school affairs and administrative duties, and lesson preparation and planning, while the reasonable job performance hours were found to be high in the order of lesson administration, lesson preparation and planning, extracurricular student guidance, and school affairs and administrative duties. As for the job categories with shorter reasonable job performance hours compared to job performance hours, they were found to be lesson administration, extracurricular student guidance, and school affairs and administrative duties. In other job categories, it was found that longer job performance hours are needed. Second, the job performance hours perceived by each subject teacher from other schools, they were found to be 2,888.3 minutes for special subject teachers and 2,536.1 minutes for general subject teachers, while showing 3,021.8 minutes for special subject teachers and 2,716.8 minutes for general subject teachers regarding reasonable job performance hours. The differences between the job performance hours and reasonable job performance hours perceived by teachers from other schools were found to be 133.5 minutes for special subject teachers and 180.7 minutes for general subject teachers.

• 대한공업교육학회지
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• v.42 no.1
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• pp.30-52
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• 2017

The purpose of this study is to investigate the duties of teachers working at secondary level technical vocational education institutes, and analyze job importance, difficulty and frequency of performance perceived by teachers. For deducing the duties of teachers working at secondary level technical vocational education institutes, they were theoretically devised by reviewing related legislations & regulations and domestic & overseas literatures. The devised duties were reviewed by 16 current teachers and 3 education experts to be revised and supplemented to complete the job model. Based on this, development of research tool was finalized, and questionnaires were used as the research tool. The results of this study are as follow. First, the job categories of teachers working at secondary level technical vocational education institutes consisted of 7 categories that are subject instruction, student instruction, class management, curriculum organization & administration, school affairs & administrative duties, PR & field practical training and expertise enhancement. Based on the CFA, they consisted of 46 sub-factors in 10 categories with 3 categories of lesson preparation & planning, lesson administration and academic evaluation for subject instruction, and 2 categories of extracurricular student guidance and school life guidance for student instruction, and class management, curriculum organization & administration, school affairs & administrative duties, PR & field practical training and expertise enhancement. Second, job importance perceived by teachers working at secondary level technical vocational education institutes was found to be high overall with 4.10, while above average in difficulty with 3.45 and average in frequency of performance with 3.12 (1-3 times a month). As for categories with high job importance, they were found to be in the order of academic evaluation (4.32), lesson preparation & planning (4.28), expertise enhancement (4.27), lesson administration (4.26), school life guidance (4.25), class management (4.17) and PR & field practical training (4.12). In regards to categories with high job difficulty, they were found to be in the order of PR & field practical training (4.07), curriculum organization & administration (3.73), expertise enhancement (3.55), school life guidance (3.48), academic evaluation (3.35) and extracurricular student guidance (3.22). As for categories with high frequency of job performance, they were found to be in the order of class management (3.88), lesson administration (3.77), school life guidance (3.52), school affairs & administrative duties (3.40) and lesson preparation & planning (3.17).

• Journal of Labour Economics
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• v.40 no.2
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• pp.31-68
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• 2017

This study examined the moonlighting behavior in Korea, to which relatively less attention has been paid. Based on the wage earners of 25 to 65 year old married, the results show that about 1.4% of the sample have dual jobs, working very long hours, on average 60 hours for a week combining both the primary job and the secondary job. The results of the fixed effects logit model on the moonlighting participation indicate that the wage rate and the hours of work in the primary job have a negative effect on moonlighting participation while the insecurity of the primary job appears to lead to a higher probability of taking a secondary job. The results of the moonlighting hours analysis suggest that hours worked in the primary job have a negative effect on moonlight hours while the wage of the primary job does not appear to have any significant effect on moonlighting hours. Interestingly enough, the wage of the secondary job appears to have a negative impact on moonlighting hours, which might be very plausible considering the long working hours moonlighters are engaged in.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.9 no.2
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• pp.145-157
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• 1999

Wood dust is created when machines are used to cut or shape wood materials. Industries of high risk of wood dust exposure are sawmills, dimension mills, furniture industries, and carpenters, etc. Health effects associated with wood dust exposure includes dermatitis, allergic respiratory effects and cancer. Health effects of wood dus t are mainly depend on the concentration, dust size and exposure time. This study were carried out to evaluate the concentration and particle size distribution of wood dust during working processes. The subjects of this study were 53 workers exposed to wood dust in 7 furniture factories and 5 musical instruments, and 5 sawmill factories. The average total wood dust concentrations measured by personal cascade impactor were $1.82{\pm}2.31mg/m^3$ in primary manufacture, $3.59{\pm}1.72mg/m^3$ in s econdary manufacture, $5.09{\pm}1.46mg/m^3$ in sanding operation. Mass median diameters of hardwoods dust were $3.36{\mu}m$ in primary manufacture, $4.25{\mu}m$ in secondary manufacture, $4.21{\mu}m$ in sanding operation. softwoods dust were $3.39{\mu}m$ in primary manufacture, $4.34{\mu}m$ in secondary manufacture. Particle size distributions showed a nearly the same pattern in each working processes. The sample concentration of all hardwood dust exceeded the Threshold Limit Value(TLV) and 20.8% of the softwood dust exceeded the Threshold Limit Value. The range of size distribution were $0.5-10{\mu}m$ in the soft and hardwood dust. The respirable dust of soft and hardwood took up 59% and above. Therefore new threshold limit value for wood dust should be needed in Korea. Also, it should be done for various studies on health effects related to occupational exposure of wood dust.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.3
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• pp.499-507
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• 2023

The core of the liquefied natural gas (LNG) carrier cargo containment system (CCS) is to store and transport LNG safely under temperatures below -163 degrees Celsius. The secondary barrier of the LNG CCS is adopted to prevent LNG leakage from CCS to the ship's hull structure. Recently, as the size of the LNG CCS increases, various studies have been conducted on the applied temperature and load ranges. The present study investigates the working condition-dependent bonding strength of the PU15 adhesives of the secondary barrier. In addition, the mechanical performance is analyzed at a cryogenic temperature of -170 degrees Celsius, and the failure surface and failure mode are investigated depending on the working condition of the bonded process. Even though the RSB and FSB-based fracture mode was confirmed, the results showed that all the tested scenarios satisfied the minimum requirement of the regulation.

• Research in Community and Public Health Nursing
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• v.28 no.4
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• pp.472-481
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• 2017

Purpose: The purpose of this study were to compare working condition, socioeconomic status, and health status between elderly and non-elderly workers and to examine the influencing factors of health status according to age groups. Methods: This study is a secondary analysis of data extracted from the 2014 Korean Working Conditions Survey. For the present analysis, 15,980 elderly workers over the age of 55 and 32,037 non-elderly workers under the age of 55 were selected. Results: The prevalence of subjective unhealthy status and poor mental health were significantly higher among the elderly workers than the non-elderly workers. The elderly workers were more likely to have lower level of education and income than the non-elderly workers. They also reported less support from colleagues and managers, however, have more decision authority. Among the elderly workers, long working hours, awkward posture, physical environmental risks, quantitative demand, decision authority, social support, age discrimination, education level, and income level were significant predictors of subjective health status or mental health. Conclusion: For keeping elderly workers healthy and productive, work environment needs to become more age-friendly. An age-friendly workplace may include: accommodative support, workers' participation, minimization of environment risk, etc.

• Korean Journal of Occupational Health Nursing
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• v.24 no.2
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• pp.132-141
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• 2015

Purpose: The purpose of this study was to investigate the relationships between psychosocial working conditions and psychological well-being depending on the gender among Korean interactive service workers. Methods: This study was a secondary analysis of the data extracted from the 2011 Korean Working Conditions Survey. For the present analysis, 15,669 workers who interact with others at work were selected. Based on the existing literature, a set of variables was chosen from the KWCS. Psychological well-being was measured using the WHO-5 well-being index. Results: The prevalence of poor psychological well-being was significantly higher among men (43.1%) than women (39.6%). Women were more likely to be exposed to demands for hiding emotions, bullying, and discrimination, whereas men were more likely to be exposed to psychological job demands, cognitive demands, demands for responsibility, role conflict and long working hours. Most factors were associated with poor well-being among women and men except demands for hiding emotions, skill discretion and development, physical violence, and sexual harassment. Conclusion: Based on these results, some practical suggestions are offered to help interactive service workers adjust to their duties.