• Structural Engineering and Mechanics
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• v.18 no.5
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• pp.541-563
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• 2004

For reaching large inelastic deformations without a substantial loss in strength, the potential plastic hinge regions of the reinforced concrete structural members should be confined by adequate transverse reinforcement. Therefore, simple and realistic representation of confined concrete behaviour is needed for inelastic analysis of reinforced concrete structures. In this study, a trilinear stress-strain model is proposed for the axial behaviour of confined concrete. The model is based on experimental work that was carried out on nearly full size specimens. During the interpretation of experimental data, the buckling and strain hardening of the longitudinal reinforcement are also taken into account. The proposed model is used for predicting the stress-strain relationships of confined concrete specimens tested by other researchers. Although the proposed model is simpler than most of the available models, the comparisons between the predicted results and experimental data indicate that it can represent the stress-strain relationship of confined concrete quite realistically.

• Korean Journal of Child Studies
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• v.35 no.5
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• pp.135-154
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• 2014

This study examined the causal relationships between parenting stress and self-efficacy of Korean mothers with an infant according to employment status using the second through fourth wave data of the Panel Study of Korean Children (PSKC). Autoregressive cross-lagged modeling was performed to test the longitudinal reciprocal relationships between the two constructs. Our results indicated that both maternal parenting stress and self-efficacy were consistent over time. The results also indicated that there was a significant cross-lagged effect of maternal parenting stress on their self-efficacy, rather than vice versa. No differences between working and non-working mothers were found in the relationship between the two constructs.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.500-503
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• 2011

Blood flow simulations in an idealized carotid bifurcation model with considering wall compliance were carried out to investigate the effect of wall elasticity on the wall shear stress and wall solid stress. Canonical waveforms of flowrates and pressure in the carotid arteries were imposed for the boundary conditions. Comparing to rigid wall model, generally, we could find an increased recirculation region at the carotid bulb and an overall reduced wall shear stress. Also, there was appreciable change of flowrate and pressure waveform in longitudinal direction. Solid and wall shear stress concentration occurs at the bifurcation apex.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.3
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• pp.547-553
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• 1990

With alumina ceramics to copper brazement of cylindrical shape, the thermal stress analysis was carried out by finite element method. Elastic and plastic behaviour was considered to copper, but only elastic behaviour was considered to alumina. Also material properties of alumina and copper were considered in not constant values but variable functions dependent on temperature. The result of analysis is shown that maximum tensile longitudinal stress is occurred at perimeter of alumina side interface and maximum compressive radial and tangential stresses are occurred at center of alumina side interface. Because of bending effect, tensile raidial and tangential stresses are occurred at near bottom of alumina, far from interface.

• Journal of the Korean Society of Mechanical Technology
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• v.13 no.4
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• pp.15-21
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• 2011

The safety at this study is investigated by flow or stress analyses due to configuration or installation direction of fuel tank in the existing CNG bus. In case of the lower ceiling with sharp type, the equivalent stress due to the explosion of fuel tank is less than the type of flat or arc. it becomes safer on passenger. In case of the installation direction of fuel tank in the existing CNG bus, the stress applied on the lower ceiling at transverse direction becomes less than at longitudinal direction. It is more stable on the safety of passenger. The harm on the explosion accident can be prevented by use of the analysis result at this study.

• Korean Journal of Occupational Health Nursing
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• v.18 no.2
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• pp.153-164
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• 2009

Purpose: This study investigates the relationship between job stress, depression, health-related behavior and type A behavior patterns among male workers at a steel factory. Methods: The study was done on 171 male workers, using the structured questionnaire. The data were collected in April, 2009 and analyzed by descriptive statistics, t-test, ANOVA, and pearson correlation coefficient. Results: The results showed that 65.5% of workers were under moderate stress, 25.7% high stress and 0.6% extremely high stress. The overall score of these workers' occupational stress was 41.9, lower than the Korean workers' average. Occupational stress was correlated with depression, type A behavior patterns, a very poor physical condition without sufficient sleep. Conclusion: Stress management program is strongly needed for these subjects working over 45 hours a week, with a very poor subjective physical condition, insufficient sleep, type A behavior patterns and signs of severe depression. Further longitudinal study is recommended to show the effect of such worker's stress management program to mitigate job-related stress.

• Journal of Korean Biological Nursing Science
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• v.24 no.4
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• pp.235-242
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• 2022

Purpose: To investigate associations of perceived stress level, serum cortisol level, and telomere length of community-dwelling adults in Korea. Methods: Data of a total of 135 community-dwelling adults aged over 40 years living in D metropolitan city from December 2020 to March 2021 were collected. Perceived stress level over the past month were measured using the Perceived Stress Score. Serum cortisol level was analyzed using a chemiluminescent microparticle immunoassay. Telomere length was determined using quantitative real-time polymerase chain reaction. The statistical package SPSS 23.0 was used to perform Chi-square test, independent t-test, and Pearson's correlation coefficient analysis. Results: There was no association between perceived stress and serum cortisol level (r = .07, p= .402). Serum cortisol level was not significantly associated with telomere length either (r = -.15, p= .081). However, the higher the perceived stress level, the shorter the telomere length (r= -.29, p= .001). Conclusion: These results suggest that perceived stress might induce physiological stress, which might partially affect gene biology. Further longitudinal research is needed to investigate the effect of perceived stress on telomere length. Intervention for relieving stress should be included in stabilizing the genetic environment of adults.

• Structural Engineering and Mechanics
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• v.73 no.2
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• pp.167-179
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• 2020

This study provides a simplified method for the evaluation of shear lag stress in rectangular box T-joints. The occurrence of shear lag phenomenon in the box T-joint generates stress concentration localized at both web-flange junctions of the beam, which leads to cracking or failure in the weld region of the joint. To prevent such critical circumstance, peak stress at the weld region is required to be checked during a preliminary design stage. In this paper, the shear lag stresses in the T-joints were evaluated using least-work solution in which the longitudinal displacements of the beam flange and web were presumed. The evaluation process considered particularly the effect of column flange flexibility, which was represented by an axial spring model, on the shear lag stress distribution. A simplified method for stress evaluation was provided to avoid solving complex mathematical problems using a stress modification factor β_s from a parametric study. The results showed that the proposed method was valid for predicting the shear lag stress in the box T-joints manually, as well compared with finite element results. The results are further summarized, discussed, and clarified that more flexible column flange caused higher stress concentration.

• Journal of Korean Critical Care Nursing
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• v.12 no.1
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• pp.22-35
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• 2019

Purpose : This study was to determine the levels of environmental stressor, posttraumatic stress disorder, and quality of life in intensive care units (ICU) survivors after intensive care, and to explore the factors affecting posttraumatic stress disorder and quality of life. Methods: With a longitudinal survey design, data were collected from 116 patients who were discharged from the ICU of a university hospital. The environmental stressor, posttraumatic stress disorder, and quality of life were measured immediately following and 1 month after the ICU discharge. Results: Of all the subjects, 16.4% experienced posttraumatic stress disorder after discharge. Multiple regression analysis revealed that ICU environmental stressors, experience of ICU readmission, using psychotropic drugs and narcotic analgesics, and ICU admission after surgery or cardiac intervention accounted for 22.2% of posttraumatic stress disorder. Posttraumatic stress disorder and sedation status when entering ICU accounted for 28.3% of the quality of life 1 month after ICU discharge. Conclusion: Nursing interventions focused on ICU environmental stressors would not only reduce environmental stress but also contribute to the reduction of posttraumatic stress disorder and later improvement of quality of life.

• Journal of the Korea Concrete Institute
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• v.18 no.5 s.95
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• pp.695-702
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• 2006

The stress distribution and the critical stresses in concrete pavements were analyzed using formulations in the transformed field domains when dual-wheel single-, tandem-, and tridem-axle loads were applied. First the accuracy of the transformed field domain analysis results was verified by comparing with the finite element analysis results. Then, the stress distribution along the longitudinal and transverse directions was investigated, and the effects of slab thickness, concrete elastic modulus, and foundation stiffness on the stress distribution were studied. The effect of the tire contact pressure related to the tire print area was also studied, and the location of the critical stress occurrence in concrete pavements was finally investigated. From this study, it was found that the critical concrete stress due to multi-axle loads became larger as the concrete elastic modulus increased, the slab thickness increased, and the foundation stiffness decreased. The number of axles did not tend to affect the critical stress ratio except for a small foundation stiffness value with which the critical stress ratio became significantly larger as the number of axles increased. The critical stress location in the transverse direction tended to move into the interior as the tire contact pressure increased, the concrete elastic modulus increased, the slab thickness increased, and the foundation stiffness decreased. The critical stress location in the longitudinal direction was under the axle for single- and tandem-axle loads, but for tridem-axle loads, it tended to move under the middle axle from the outer axles as the concrete elastic modulus and/or slab thickness increased and the foundation stiffness decreased.