• Steel and Composite Structures
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• v.50 no.4
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• pp.403-418
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• 2024

In this paper, vibration and energy absorption characteristics of a nanostructure which is composed of two embedded porous annular/circular nanoplates coupled by a viscoelastic substrate are investigated. The modified couple stress theory (MCST) and the Gurtin-Murdoch theory are applied to take into account the size and the surface effects, respectively. Furthermore, the structural damping effect is probed by the Kelvin-Voigt model and the mathematical model of the problem is developed by a new hyperbolic higher order shear deformation theory. The differential quadrature method (DQM) is employed to obtain the out-of-phase and in-phase frequencies of the structure in order to predict the dynamic response of it. The acquired results reveal that the vibration and energy absorption of the system depends on some factors such as porosity, surface stress effects, material length scale parameter, damping and spring constants of the viscoelastic foundation as well as geometrical parameters of annular/circular nanoplates. A bird's-eye view of the findings in the research paper offers a comprehensive understanding of the vibrational behavior and energy absorption capabilities of annular/circular porous nanoplates. The multidisciplinary approach and the inclusion of porosity make this study valuable for the development of innovative materials and applications in the field of nanoscience and engineering.

• Korean Journal of Social Welfare
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• v.62 no.2
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• pp.135-159
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• 2010

This study is thing about marital adjustment of marriage migration females. This research inspected relational and influential factors that has consequences for the marital adjustment. The subjects of research are 172 marriage migration females lived in Busan. Data were analyzed by MANOVA, Multiple Regression. The results are following: First, this study found that marriage migration female's marital satisfaction are significantly influenced by spousal support, family stress, level of communication. And marriage migration female's divorce intention are significantly influenced by children number, family stress. And marriage migration female's couple loving are influenced by length of marriage, spousal support, level of communication. Second, family stress is the most powerful factor to predict marital adjustment. Therefore the lower family stress is the better marital adjustment. And through this study I found that marital adjustment is more important family stress than acculturative stress.

• Journal of Families and Better Life
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• v.20 no.6
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• pp.49-60
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• 2002

This study focused on family stresses and coping strategies among commuting couples. The participants of this study consisted of a national samples of 134 couples(268 individuals), who had been commuting for at least six months. The major findings obtained from the study are summarized in the following: First, the degree of family stresses among commuting couples was 2.98, when the maximal stress value was set to 5.0. No difference in the level of stress was detected from the roles of the wife and those of the husband. The most stressful aspect for the commuting couples came from the role of parents who care for their children. The second stressful aspect was their responsibility for their own parents, and finally the stress from the housework and maintenance of their marital lives followed next. There was no difference between the wives and husbands on the stressors. Secondly, the level of the coping strategies developed by the commuting couples themselves against their stresses was 3.37, when the maximal stress coping value was set to 5.0. Again, there was no difference in this level between wives and husbands. Among the strategies, they used ‘cognitive restructuring’the most frequently; sharing their responsibilities with other members in family life came next; and developing their own techniques to manage their stresses followed. Thirdly, the ages of the couple, the age of the first child, type of jobs, duration of the marriage and commute, and frequency of meeting affected the level of family stress among commuting couples. Finally, commuting couples developed quite different strategies to cope with their family stresses, and religion and family type affected significantly the type of coping strategies.

• Journal of Families and Better Life
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• v.21 no.2
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• pp.175-185
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• 2003

The purpose of this study was to investigate whether there is any difference between the dual residence couples and the single residence couples in terms of the situation of child care, development of their child and mother's parenting guilty or parenting stress. Also, this study aimed to explore the variables which influence parenting guilty and parenting stress of dual residence mothers. The 178 mothers of three to eight tear-old participated the survey. Half of them were dual residence mothers and another half were those of single residence. These two groups were matched in terms of the occupation of the mother and the age of the child. Major finding were as follows. 1) Compared with single residence couples, dual residence couples used multiple methods of child care. And they depended maternal families more than paternal ones as a care-giver. They also payed much more for the child care than single residence couples. 2) Children of the dual residence couples did not differ with those of the single residence couples in terms of cognitive and social development. 3) Dual residence mothers had more parenting guilty than those of single residence while these two groups did not differ in terms of parenting stress. 4) While dual residence mother's parenting guilty was significantly related with the amount of information provided by the paternal families, their parenting stress was significantly related with the frequencies of communicating with the husband, the mother's age, the flexibility of time in the mother's work place, the mother's orientation to the career, and the supports of the husband. In conclusion, dual residence families in Korea were not so negative as expected. Furthermore, this study suggests that the parenting difficulties of the dual residence mothers could be decreased by the change of social and economic situations and the psycho-social support of the husband.

• Structural Engineering and Mechanics
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• v.33 no.2
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• pp.257-260
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• 2009

• Women's Health Nursing
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• v.27 no.2
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• pp.141-152
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• 2021

Purpose: This study was conducted to develop a couple-centered antenatal education program and to test the program's feasibility. Methods: With a preliminary-experimental study design, 33 pregnant couples who were expecting their first child participated in this study. The program consisted of four sessions (1 hour/session/week) of education and counseling. Data were collected before and after the intervention from September 2018 to April 2019 at a women's hospital in Daejeon, Korea, with demographic data forms, the Edinburgh Postnatal Depression Scale, Perceived Stress Scale, Maternal-Fetal Attachment Scale, Korean Newborn Care Confidence Scale, Wijma Delivery Expectancy/Experience Questionnaire, and Dyadic Adjustment Scale-10. Results: The pregnant women and their husbands were on average 32.30±3.10 and 33.21±6.25 years old, respectively. The mean marriage duration was 2.34±1.63 years, the gestational age was 31.30±2.66 weeks, and 78.8% of the couples had a planned pregnancy. After the program, both the pregnant women and their husbands showed significant improvements in attachment to the fetus and confidence in providing infant care. Prenatal depression, prenatal stress, and fear of childbirth in pregnant women significantly decreased after completing the program. However, the dyadic adjustment score did not change significantly either in the pregnant women or their husbands. Conclusion: A couple-centered antenatal education program seems to be effective for couples adjusting to parenthood, but further studies should explore ways to have a positive impact on couples' relationships.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.05a
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• pp.209-212
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• 2001

It is known that the mim forming processes show somewhat different phenomena compared with the conventional metal forming processes, namely, the size effect, enhanced friction effect and etc. Such typical phenomena, however, are not predicted by the conventional finite element analysis, which has been an efficient numerical tool to predict the metal forming processes. It is due to the fact that the constitutive relations used does not describe the microstructural characteristics of the materials. In the present investigation, the finite element formulation using the rate-dependent rigid plastic crystal plasticity model of the face-centered cubic materials is conducted to predict the micro mechanical behaviors during the mim forming processes. The finite element analysis, however, provides mesh-dependent solutions for the intragranular deformations. Therefore, the couple stress energy is additionally introduced into the variational principle and formulated within the framework of the rigid plastic finite element method to obtain mesh-independent solutions. Micro deformations of single crystal and bicrystal with various orientations are calculated to show the potential of the developed formulation.

• Structural Engineering and Mechanics
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• v.61 no.2
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• pp.209-220
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• 2017

The purpose of this paper is to study the geometrically nonlinear free vibration of functionally graded nano/micro beams (FGNBs) based on the modified couple stress theory. For practical applications, some analytical expressions of nonlinear frequencies for FGNBs on a nonlinear Pasternak foundation are developed. Hamilton's principle is employed to obtain nonlinear governing differential equations in the context of both Euler-Bernoulli and Timoshenko beam theories for a comprehensive investigation. The modified continuum theory contains one material length scale parameter to capture the size effect. The variation of two-constituent material along the thickness is modeled using Reddy's power-law. Also, the Mori-Tanaka method as an accurate homogenization technique is implemented to estimate the effective material properties of the FGNBs. The results are presented for both hinged-hinged and clamped-clamped boundary conditions. The nonlinear partial differential equations are reduced to ordinary differential equations using Galerkin method and then the powerful method of homotopy analysis is utilized to obtain the semi-analytical solutions. Eventually, the presented analytical expressions are used to examine the influences of the length scale parameter, material gradient index, and elastic foundation on the nonlinear free vibration of FGNBs.

• Structural Engineering and Mechanics
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• v.70 no.3
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• pp.351-365
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• 2019

In this paper, free vibration of Cooper-Naghdi micro sandwich cylindrical shell with saturated porous core and reinforced carbon nanotube (CNT) piezoelectric composite face sheets is investigated by using first order shear deformation theory (FSDT) and modified couple stress theory (MCST). The sandwich shell is subjected to magneto-thermo-mechanical loadings with temperature dependent material properties. Energy method and Hamilton's principle are used for deriving of the motion equations. The equations are solved by Navier's method. The results are compared with the obtained results by the other literatures. The effects of various parameters such as saturated porous distribution, geometry parameters, volume fraction and temperature change on the natural frequency of the micro-sandwich cylindrical shell are addressed. The obtained results reveal that the natural frequency of the micro sandwich cylindrical shell increases with increasing of the radius to thickness ratio, Skempton coefficient, the porosity of the core, and decreasing of the length to radius ratio and temperature change.

• Advances in nano research
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• v.12 no.6
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• pp.567-581
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• 2022

The free and forced vibration in addition to electric energy harvesting of a piezoelectric disk resting on two-parameter foundation modeled by modified couple stress as well as Kirchhoff plate theory is probed. The governing equations and boundary conditions are obtained using Hamilton's principle. Then, the free and forced vibration are solved using numerical solutions, generalized differential quadrature method (GDQM) and Newmark-beta method. The forced vibration is resulted from a base excitation load. Also, the possible voltage which can be harvested from this system is obtained using generalized integral quadrature method. The validity of the formulation and solution procedure is confirmed using a compassion study. The impact of parameters such as length effect, inner to outer radius ratio, and foundations parameters on the free and forced vibration as well as energy harvesting is investigated in detail. This paper can be a basis for future studies in the area of piezoelectric harvesters in small scales.