• Structural Engineering and Mechanics
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• v.38 no.3
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• pp.333-347
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• 2011

This paper shows the solution for an orthotropic disk under the plane strain condition obtained with complex stress functions. These stress functions were induced by Lekhnitskii and expanded by one of the authors. Regarding diametrical compression test, the finite element method poses difficulties in representing the concentrated force because the specimens must be divided into finite elements during calculation. On the other hand, the method shown in this study can exactly represent this force. Some numerical results are shown and compared with those obtained under the plane stress condition for both stress and displacement. This comparison shows that the differences between the tensile stresses occurred under the plane strain condition and also that the differences under a plane stress condition increase as the orthotropy ratio increases for some cases.

• Perspectives in Nursing Science
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• v.13 no.1
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• pp.10-16
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• 2016

Purpose: This study aimed to investigate differences in drinking scores according to stress and depression. Methods: A secondary analysis of the 5th and 6th Korea National Health and Nutrition Examination Surveys was conducted. Complex sampling design data analysis was performed in order to identify differences in Alcohol Use Disorder Identification Test (AUDIT) scores according to stress and depression among 1,732 unmarried women. Results: The average AUDIT score was 6.14 in unmarried women. There were significant differences in AUDIT scores in terms of stress and depression. Conclusion: Practical programs that can prevent alcohol drinking for unmarried women are suggested. Programs for alcohol-related problems should include stress and depression management.

• Journal of muscle and joint health
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• v.28 no.1
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• pp.61-69
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• 2021

Purpose: This study investigated the mediating effect of perceived stress in the relationship between subjective health and depression in patients with coronary artery disease. Methods: This secondary analysis study used data from the 2016-2018 Korea National Health and Nutrition Examination Survey (KNHANES). Study participants included 466 patients over 20 years of age with coronary artery disease. Measures included questions about general characteristics, subjective health, perceived stress, and depression. The data were analyzed using complex sample design, descriptive analysis, Rao-Scott ��2 statistic, and multivariate logistic regression analysis with the SPSS 24.0 program. Results: Subjective health influenced depression, and perceived stress partially mediated it. Conclusion: To prevent depression in patients with coronary artery disease, it is necessary to develop effective stress management strategies.

• Journal of Biosystems Engineering
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• v.39 no.3
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• pp.244-252
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• 2014

Purpose: The development of an efficient in vitro cell culture device to process various cells would represent a major milestone in biological science and engineering. However, the current conventional macro-scale in vitro cell culture platforms are limited in their capacity for detailed analysis and determination of cellular behavior in complex environments. This paper describes a microfluidic-based culture device that allows accurate control of parameters of physical cues such as pressure. Methods: A microfluidic device, as a model microbioreactor, was designed and fabricated to culture Saccharomyces cerevisiae and Chlamydomonas reinhardtii under various conditions of physical pressure stimulus. This device was compatible with live-cell imaging and allowed quantitative analysis of physical cue-induced behavior in yeast and microalgae. Results: A simple microfluidic-based in vitro cell culture device containing a cell culture channel and an air channel was developed to investigate physical pressure stress-induced behavior in yeasts and microalgae. The shapes of Saccharomyces cerevisiae and Chlamydomonas reinhardtii could be controlled under compressive stress. The lipid production by Chlamydomonas reinhardtii was significantly enhanced by compressive stress in the microfluidic device when compared to cells cultured without compressive stress. Conclusions: This microfluidic-based in vitro cell culture device can be used as a tool for quantitative analysis of cellular behavior under complex physical and chemical conditions.

• Applied Microscopy
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• v.38 no.3
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• pp.213-219
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• 2008

The plasticity of nervous system is generated not only due to changes in neurons but also due to changes in neuroglial cells. Astrocyte is important for maintaining the normal brain function and controlling the neuronal functions. The amygdala receives an array of important sensory information of danger signals. This information is further transduced and integrated to produce the highly adaptive emotion, fear. In this study, morphometric changes in the cell bodies of astrocytes in the amygdala, induced by prenatal stress and restraint stress were examined. For this purpose. rats were classified into 4 groups; control group (CON), only restraint-stressed (starting on P90 for 3 days) group (CONR), prenatally-stressed group (PNS), and prenatally and restraint (on P90 for 3 days) stressed group (PNSR). Astrocytes were verified with anti-GFAP immunohistochemistry, counter stained with methylene blue/azure II and were examined using the Neurolucida. Results showed that astrocytes in the amygdala of PNS rats had significantly larger cell bodies than did CON rats and this was enhanced further by restraint stress. Thus this data showed that hypertrophy of the astrocytic cell bodies of amygdala complex is induced by prenatal and restraint stress.

• Journal of Environmental Health Sciences
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• v.38 no.3
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• pp.195-203
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• 2012

Objectives: This paper aims to investigate the influence on stress hormones of job stress resulting from firefighting duties, as well as the degree of such influence. Methods: KOSS-26 and stress hormones such as norepinephrine (NE), epinephrine (EPI), adrenocorticotrophic hormone (ACTH), and cortisol were analyzed for 191 male firefighters from the western area of Incheon, the Incheon Industrial Complex, and Bucheon, Korea. Job stress and stress hormones were compared between a office working group and field-working group. Results: There was no significant difference in EPI and ACTH between the two groups. Change of stress hormones prior to engaging in typical duties, following typical duties, and immediately after field activities was examined. All the EPI, ACTH, and cortisol showed statistically significant changes with time, but not NE in the blood. In the field-working group, the cortisol levels in the blood of the firefighting and rescue groups showed notable differences depending on the time at which the measurements were taken. Conclusion: The differences in stress hormone levels depending on the type of duties of the firefighters were identified. Thus, interventions proper to job requirements is required in order to ease stress.

• International Journal of Naval Architecture and Ocean Engineering
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• v.8 no.6
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• pp.615-630
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• 2016

Complex stress distributions often exist in ocean engineering structures. This stress influences structural vibrations. Finite Element Methods exhibit some shortcomings for solving non-uniform stress problems, such as an unclear physical interpretation, complicated operation, and large number of computations. Analytical methods research considers mainly uniform stress problems, and often, their methods cannot be applied in practical marine structures with non-uniform stress. In this paper, an analytical method is proposed to solve the vibration of plates with general stress distributions. Non-uniform stress is expressed as a special series, and the stress influence is inserted into a vibration equation that is solved through decoupling to obtain an analytical solution. This method has been verified using numerical examples and can be used in arbitrary stress distribution cases. This method requires fewer computations and it provides a clearer physical interpretation, so it has advantages in some qualitative research.

• Molecules and Cells
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• v.39 no.1
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• pp.31-39
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• 2016

The peroxiredoxins (Prxs) constitute a very large and highly conserved family of thiol-based peroxidases that has been discovered only very recently. We consider here these enzymes through the angle of their discovery, and of some features of their molecular and physiological functions, focusing on complex phenotypes of the gene mutations of the 2-Cys Prxs subtype in yeast. As scavengers of the low levels of $H_2O_2$ and as $H_2O_2$ receptors and transducers, 2-Cys Prxs have been highly instrumental to understand the biological impact of $H_2O_2$, and in particular its signaling function. 2-Cys Prxs can also become potent chaperone holdases, and unveiling the in vivo relevance of this function, which is still not established, should further increase our knowledge of the biological impact and toxicity of $H_2O_2$. The diverse molecular functions of 2-Cys Prx explain the often-hard task of relating them to peroxiredoxin genes phenotypes, which underscores the pleiotropic physiological role of these enzymes and complex biologic impact of $H_2O_2$.

• Structural Engineering and Mechanics
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• v.77 no.5
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• pp.691-703
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• 2021

Reinforced concrete (RC) beams can be subjected to a complex combination of shear forces (V), torsional moments (T), flexural moments (M) and axial loads (N). This paper proposes a unified approach for the analysis of these elements. An existing model for the analysis of orthogonally reinforced concrete membrane elements subjected to in-plane shear and normal stresses is generalized to apply to the case of beams subjected to the complex loading. The combination of V and T can be critical. Torsion is modelled using the hollow-tube analogy. A direct equation for the calculation of the thickness of the equivalent hollow tube is proposed, and the shear stresses caused by V and T are combined using a simple approach. The development and the evaluation of the model are described. The calculations of the model are compared to experimental data from 350 beams subjected to various combinations of stress-resultants and to the calculations of the ACI and the CSA codes. The proposed model provides the most favorable results. It is also shown that it can accurately model the interaction between V and T. The proposed model provides a unified treatment of shear in beams subjected to complex stress-resultants and in thin membrane elements subjected to in-plane stresses.

• 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.