• Journal of the Ergonomics Society of Korea
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• v.36 no.5
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• pp.601-607
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• 2017

Objective: A method to assess the risk level of agricultural works considering work posture and working time was suggested, and the method was applied to the major fruit crops. Background: It is not complete to analyze only work postures when assessing risk level of agricultural works. Method: $3{\times}3$ matrix was employed, in which the severity level was taken from the REBA method and exposure level was taken from the working time, using the criteria of caution zone/hazard zone. Results: Among the 5 major fruit crops(apple, pear, grape, peach, persimmon), the highest level of ergonomic risk was found in the apple and pear, while medium level was found in other 3 crops, mainly because the working time was less in the 3 crops. Conclusion: It was found that when assessing the overall ergonomic risk of agricultural works, work posture and working time should be considered at the same time. Application: The suggested method could be applied to other non-cyclic tasks.

• Journal of Korean Biological Nursing Science
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• v.19 no.3
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• pp.206-213
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• 2017

Purpose: The purpose of the study was to compare salivary cortisol levels, self-reported occupational stress, and anxiety before duty to those after duty in the shift and regular work nurses, and the relationships among them. Methods: Thirty nurses working in a tertiary hospital participated in the study. Salivary specimens were collected before and after daytime duty for 2 days. The occupational stress and state anxiety were also evaluated using self-report questionnaires. Results: The average level of salivary cortisol was $0.40{\mu}g/dL$ before duty and $0.20{\mu}g/dL$ after duty in Korean nurses. Overall levels of salivary cortisol, self-reported occupational stress, and anxiety were higher in shift working nurses than regular working nurses. In shift working nurses, the salivary cortisol gap between before and after duty was attenuated on the first day of daytime duty. Significant positive correlation was found between the level of cortisol before duty and anxiety after duty. Conclusion: Strategies to alleviate occupational stress and anxiety are needed for shift working nurses, especially for those with elevated levels of cortisol. It seems to require 3days to recover from attenuated cortisol rhythm during nighttime duty in shift working nurses.

• Child Health Nursing Research
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• v.13 no.3
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• pp.329-337
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• 2007

Purpose: This study was done to describe the essential structure of the lived experience of working women raising children. Method: Data were collected from 10 employed women with children who were under 2 years of age. The analysis of the data was done using the phenomenological analytic method suggested by Colaizzi (1978). Results: In this study, 6 essential themes were extracted: 'knowing by intuition child-rearing is difficult', 'having guilt-conscious of not being able to perform duties as a mother', 'hard work of maintaining two jobs', 'Lost self', 'realizing that one has become amother', 'thirsting for a social support system'. Conclusion: With a rapidly increasing number of working women, the significance of this study in the field of nursing is in understanding the child-rearing experience of working women. The findings indicate the need for a systemic and emotional support system for working women raising children.

• Phonetics and Speech Sciences
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• v.3 no.4
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• pp.95-102
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• 2011

The purpose of this study was to identify the characteristics of the phonological discrimination ability and phonological working memory of 10 typically developing children aged 4, and 10 other children with Specific Language Impairments whose language age is similar. In orders to compare their phonological discrimination ability among phonological awareness, discrimination tasks were conducted at the syllable and phoneme levels. Also, in order to compare their phonological working memory, the subjects repeated nonsense syllables. The research results may be summarized as follows: First, the children with Specific Language Impairments demonstrated a lower performance than the typically developing children in phonological discrimination ability at both syllable and phoneme levels, and the difference between the groups was statistically significant. Second, the children with Specific Language Impairments exhibited a lower phonological working memory performance in all syllables compared with normal children. Although there was no significant difference in 2 and 3 syllables, a significant difference appeared as the length of the syllables became longer from 4 to 6 syllables. It is deemed necessary to conduct research into qualitative and quantitative differences through an formal assessment of the phonological awareness and phonological working memory of children with Specific Language Impairments.

• Tribology and Lubricants
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• v.26 no.4
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• pp.230-239
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• 2010

Mechanical face seal installed in boiler feedwater pump prevents leakage of working fluid using thin fluid film between stator and rotor. If the leakage of working fluid exceeds the allowable volume, serious malfunction of boiler feedwater pump will be happen. The thinner fluid film exists between stator and rotor, the less working fluid leaks out. However, if the thickness of fluid film is not enough, the wear of seal face will be increased. And it causes the decrease in life of mechanical face seal. Therefore appropriate design is necessary to maximize the performance and life of mechanical face seal. In this study, numerical analysis using finite volume method was conducted to investigate the static characteristics of wavy mechanical face seals which have 4 different wavy surface profiles on rotor. As a result, opening force, leakage volume of working fluid and friction torque were obtained. For the same minimum film thickness, the static characteristics of mechanical face seal were affected by the wavy surface profile which can change the thickness of working fluid film and pressure distribution.

• Korean Journal of Human Ecology
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• v.9 no.1
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• pp.71-84
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• 2000

The objective of this research is to investigate the relation between the parenting stress, recognized by the working mothers, and associated variables systematically. For the purpose, I analyzed the demographic of the working mothers and surrounding variables at the levels of microsystem, mesosystem, and macrosystems, to relate with respect to the parenting stress problem. The research composes the sample space of working mothers having children less than 6 years old. The data were analyzed by the statistical method based on frequency, percentile, Pearson's correlation, hierachical and multiple regression. The main results of the research can be summarized as follows: According to the independent effects of diverse ecological systematic variables, there are shown that 11 independent variables can describe about 55.6% of the parenting stress of the working mothers. Among these variables, 'satisfaction about the child care' is the most significant factor, which covers about 34.5%. Additionally, the next significances are observed from such variables as 'temperament of children' (8.2%), 'satisfaction of marriage' (5.1%), 'support of spouse' (1.5%), 'level of education' (1.9%) and so on. In conclusion, it is strongly recommended to compensate and restructure the child care systems more systematically, to afford more reliable parenting environment to the dual earner mothers and fathers and children simultaneously.

• International Journal of Highway Engineering
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• v.14 no.4
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• pp.51-61
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• 2012

PURPOSES : This study deals with the working life of polymer concrete, which is typically used as a repair or overlay material for portland cement concrete pavements. METHODS : In the scope of this study, laboratory testing was conducted on fresh MMA modified UP polymer concrete, which uses an MMA monomer for viscosity adjustment and strength improvement of UP resin. The experimental variables were temperature (-20 to $+20^{\circ}C$) and binder components (MMA, MEKPO, and DMA). RESULTS : The result showed that the optimum binder ratios for polymer concrete production were 12, 11, and 10 wt.% when the MMA contents were 20, 30, and 40 wt.%, respectively. The working life of polymer concrete depending on temperature and binder components could be expressed by a logarithmic functional formula. The coefficient of variation for each binder component was the highest for DMA content while the lowest for MEKPO content. Also, the contents of each binder component for ensuring the working life of 60 minutes were proposed. CONCLUSIONS : Ultimately, the present study derived a linear regression equation estimating 60 minutes working life based on the setting times of each binder component.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.4
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• pp.298-303
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• 2013

In this study, the W-interconnected dye-sensitized solar cell (DSSC) modules composed of a number of rectangular cells connected in series were investigated, where neighboring cells are processed in reverse. The DSSC modules, a module of dimension about 200 mm ${\times}$ 200 mm, were fabricated with different working electrode width ranging from 5 mm to 21 mm. The short-circuit current of the module increased as the working electrode width increased. Whereas, the decrease in the working electrode width resulted in the increase of the conversion energy efficiency, fill factor, and open-circuit voltage, which is explained by the fact that the possibility that electrons are recombined along their path on the transparent conductive oxide substrate decreases. The module with the conversion energy efficiency of 3.59% was obtained with the working electrode width of 5 mm.

• Journal of the Korean Society for Heat Treatment
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• v.27 no.3
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• pp.121-126
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• 2014

High-nitrogen Fe-18Mn-18Cr-N austenitic steels with higher yield strength have been recently developed and used for generator retaining rings because they have non-magnetic, high strength, high ductility, and good corrosion resistance. In the present study, a high-nitrogen Fe-18Mn-18Cr-0.61N austenitic steel was fabricated and then tensile and Charpy impact tests were conducted on them in order to investigate the effect of cold working on the mechanical properties. Although the yield and tensile strengths usually increased with cold working, the ductility and impact toughness significantly decreased after cold working. On the other hand, the high-nitrogen austenitic steel exhibited a ductile-brittle transition due to unusual brittle fracture at low temperatures despite having a face-centered cubic structure. The ductile-brittle transition temperature obtained from Charpy impact tests could be remarkably increased by $60^{\circ}C$ after 20% cold working because of the enhanced cleavage-like brittle fracture.

• Journal of Biosystems Engineering
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• v.31 no.1 s.114
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• pp.16-23
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• 2006

Depth and working load control is one of the most important technique in control system for tractor rotary implement automation. Keeping the depth consistent is critical to bring along crops and to improve the efficiency and quality of the following operations. Keeping the load of engine consistent is an essential factor for the efficiency of operation and engine protection of tractor. In this study we investigated the possibility of application of depth and working load control system for tractor using a proportional valve through field tests. Depth control was implemented by the ascent and descent of 3 point linkage for the change of setting depth. There were 4 mm and 5.2 mm control deviations for setting depths of 50mm and 100mm, respectively. Load control was operated appropriately by the ascent and of descent of 3 point link for the change of setting working load. The standard deviations between setting load and engine load were 171 rpm at 1.3 km/h and 164 rpm at 2.3 km/h tractor travel velocity. The results of experiment showed that the characteristics of response was sufficient to be used as the implement depth and working load control system for tractor using proportional valve.