• 대한기계학회논문집A
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• 제25권11호
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• pp.1802-1812
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• 2001

The theoretical method is developed to investigate the effects of ring stiffeners on free vibration characteristics and transient response for the ring stiffened composite cylindrical shells subjected to the impulse pressure Loading. In the theoretical procedure, the Love's thin shell theory combined with the discrete stiffener theory to consider the ring stiffening effect is adopted to formulate the theoretical model. The concentric or eccentric ring stiffeners are laminated with composite and have the uniform rectangular cross section. The modal analysis technique is used to develop the analytical solutions of the transient problem. The analysis is based on an expansion of the loads, displacements in the double Fourier series that satisfy the boundary conditions. The effect of stiffener's eccentricity, number, size, and position on transient response of the shells is examined. The results are verified by comparison with FEM results.

• 대한기계학회논문집A
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• 제23권11호
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• pp.2040-2049
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• 1999

The Rayleigh-Ritz method is used to investigate the natural frequencies and mode shapes of the ring stiffened cylindrical shells with a rectangular cutout. The cutout is located on the center of the shell. The Love's thin shell theory combined with the discrete stiffener theory is adopted to formulate the analytical model of the shell. The effect of stiffener eccentricity, number, and position on vibration characteristics of the shell is examined. Also the effect of cutout size is examined. By comparison with previously published analytical and new FEM results, it is shown that natural frequencies and mode shapes can be determined with adequate accuracy.

• 부모자녀건강학회지
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• 제10권2호
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• pp.172-181
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• 2007

The purpose of this study was to review the concept, type and factors that affect child rearing attitude of parents and suggest desirable child rearing attitude of parents. Child rearing attitude of parents not only decide the quality of parent-child relationship but also affect child intellectual, emotional, social development and character. Many theorists suggest the type of child rearing attitude of parents, Schaefer's theory is commonly accepted. This model divided into 4 types, affectional-automatic attitude, affectional-controling attitude, rejecting-automatic attitude, rejecting-controling attitude. Through this study, confirmed factors that affect child rearing attitude of parents were family social position, parent's age and educational level, child gender. And other factors were mother has a job or not, marriage satisfaction, number of child and etc. Desirable parent's child rearing attitude were parent's consistency, understanding and acceptance of parents, parent's ideal behavior, democratic attitude of parents, parent's love for their children.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집A
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• pp.883-888
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• 2001

The theoretical method is developed to investigate the effects of ring stiffeners on free vibration characteristics and transient response for the ring stiffened composite cylindrical shells subjected to the impulse pressure loading. In the theoretical procedure, the Love's thin shell theory combined with the discrete stiffener theory to consider the ring stiffening effect is adopted to formulate the theoretical model. The concentric or eccentric ring stiffeners are laminated with composite and have the uniform rectangular cross section. The modal analysis technique is used to develop the analytical solutions of the transient problem. The analysis is based on an expansion of the loads, displacements in the double Fourier series that satisfy the boundary conditions. The effect of stiffener's eccentricity, number, size, and position on transient response of the shells is examined. The theoretical results are verified by comparison with FEM results.

• Steel and Composite Structures
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• 제37권5호
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• pp.621-632
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• 2020

This research deals with the study of vibrational behavior of armchair and zigzag single-walled carbon nanotubes invoking extended Love shell theory. The effects of different physical and material parameters on the fundamental frequencies are investigated. By using volume fraction for power law index, the fundamental natural frequency spectra for two forms of single-walled carbon nanotubes are calculated. The influence of frequencies against length-to-diameter ratios with varying power law index are investigated in detail for these tubes. To discretize the governing equation in eigen-value form, wave propagation approach is developed. Complex exponential functions have been used and the axial model depends on boundary condition that has been described at the edges of carbon nanotubes to calculate the axial modal dependence. Computer software MATLAB is utilized for the frequencies of single-walled carbon nanotubes and current results shows a good stability with comparison of other studies.

• Structural Engineering and Mechanics
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• 제88권4호
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• pp.355-368
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• 2023

Employing the non-local strain gradient theory (NSGT), this paper investigates the nonlinear resonance characteristics of functionally graded material (FGM) nanoshells with initial geometric imperfection for the first time. The effective material properties of the porous FGM nanoshells with even distribution of porosities are estimated by a modified power-law model. With the guidance of Love's thin shell theory and considering initial geometric imperfection, the strain equations of the shells are obtained. In order to characterize the small-scale effect of the nanoshells, the nonlocal parameter and strain gradient parameter are introduced. Subsequently, the Euler-Lagrange principle was used to derive the motion equations. Considering three boundary conditions, the Galerkin principle combined with the modified Lindstedt Poincare (MLP) method are employed to discretize and solve the motion equations. Finally, the effects of initial geometric imperfection, functional gradient index, strain gradient parameters, non-local parameters and porosity volume fraction on the nonlinear resonance of the porous FGM nanoshells are examined.

• Advances in nano research
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• 제16권6호
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• pp.601-613
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• 2024

A new analytical buckling solution of a thermo-electro-magneto-elastic (TEME) cylindrical nano-shell made of BiTiO₃-CoFe₂O₄ materials is obtained based on Hamiltonian approach. The Winkler and Pasternak elastic foundations as well as thermo-electro-magneto-mechanical loadings are applied, and two different types of edge conditions are taken into the investigation. According to nonlocal strain gradient theory (NSGT) and surface elasticity theory in conjunction with the Kirchhoff-Love theory, governing equations of the nano-shell are acquired, and the buckling bifurcation condition is obtained by adopting the Navier's method. The detailed parameter study is conducted to investigate the effects of axial and circumferential wave numbers, scale parameters, elastic foundations, edge conditions and thermo-electro-magnetic loadings on the buckling behavior of the nano-shell. The proposed model can be applied in design and analysis of TEME nano components with multi-field coupled behavior, multiple edge conditions and scale effect.

• Journal of the Korean Data and Information Science Society
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• 제20권4호
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• pp.673-684
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• 2009

텔레마케팅의 영업특성상 전화 응대를 한 고객에게 초기 적절한 상품을 추천하여 보험가입을 유치하는 것이 가장 중요하다. 따라서 고객의 선호상품 및 선호시간을 고려한 고객 선별과 타겟팅을 어떻게 진행하느냐에 따라 거수보험료 차이가 발생한다. 본 연구는 데이터마이닝 기법 중 로지스틱회귀모형을 이용하여 생명보험사 아웃바운드 텔레마케팅 영업을 지원하는데 있어서 그 효과를 검증하고자 하였다. 기존의 가입상품에 대한 고객반응정보와 L생명보험사 영업 전략에 따라 연령을 구간화하고 가족사랑보험, 상해보험, 암보험 상품에 대한 모델링을 진행하였다. 설정된 모델을 바탕으로 캠페인 진행시 기존 마케팅 방식과 모델방식으로 고객을 추출하고 실행결과를 통해 모델의 우수성을 입증하였다. 또한 시간이 지남에 따라 설정한 모델이 노후화되고 영업이익이 줄어듦에 따라 지속적으로 영업이익을 극대화 할 수 있도록 모델갱신주기를 도출하였다.

• 동서간호학연구지
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• 제26권1호
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• pp.80-90
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• 2020

Purpose: Sex education should be given priority to address dating violence. Comprehensive sex education has been developed based on a nonviolent communication model between couples for the smooth resolution of problems with the opposite sex. The purpose of this study was to develop and apply Comprehensive Sex Education for unmarried couples in their 20s-30s and to examine the effects on sex communication, problem-solving communication, and relationship competence. Methods: This study developed a total of six web-based sex education sessions. A comprehensive sex education program combined with nonviolent communication between couples was developed based on the UNESCO Sex Education Guidelines. A pre- and post-equivalence control design was used to provide moderation-based sex education to compare the effects on gender communication, communication dissatisfaction, and relationship development. Results: We developed a comprehensive sex education program for couples that took three minutes per episode, on a web-based basis. Sex communication, problem-solving communication, and love relationship competence showed significant pre- and post-test differences between the experimental and control groups. Conclusion: The program of this study is an attempt to introduce Korea to comprehensive sex education, which has already been shown to be effective through numerous verification processes abroad and will provide assistance in forming future relationships between lovers.

• Smart Structures and Systems
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• 제14권2호
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• pp.71-83
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• 2014

The purpose of this paper is to investigate the flexible structure of parabolic shell using photostrictive actuators. The analysis is made to know its dynamic behavior and light-induced control forces for coupled parabolic shell. The effects of an actuator location as well as membrane and bending components under the control action have been analyzed considering the approximate spherical model. The parabolic membrane shell accuracy is being mathematically approximated and validated comparing the light induced control forces using approximate equivalent spherical shell model. The parabolic shell with kapton smart material and photostrictive actuators has been used to formulate the governing equation in the transverse direction. The Kirchhoff-Love assumptions are used to obtain the governing equation of shell with actuator. The mechanical membrane forces and bending moments for parabolic thin shell with actuator is used to analyze the dynamic effect. The results show that membrane control action is much more significant than bending control action. Photostrictive actuators oriented along circumferential direction (actuator-2) can give better control effect than actuators placed along longitudinal direction (actuator-1). The slight difference is observed between spherical and parabolic shell for a surface with focal length to the diameter ratio of 1.00 or more than unity. Space applications often have the shape of parabolical shells or shell of revolution, due to their required focusing, aiming, or reflecting performance. The present approach is focused that photostrictive actuators can effectively control the vibration of parabolical membrane shell. Also, the actuator's location plays an important role in defining the control force.