• Proceedings of the Computational Structural Engineering Institute Conference
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• 1998.04a
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• pp.449-456
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• 1998

A consistent finite element formation and analytic solutions are presented for spatial stability of thin-walled circular arch. The total potential energy is derived by applying the principle of linearized virtual work and including second order terms of finite semitangential rotations. As a result the energy functional corresponding to the semitangential rotation is obtained, in which the elastic strain energy terms are considered restrained warping effects. We have obtained analytic solution for the lateral buckling of monosymmetric thin-walled curved beam subjected to pure bending or uniform compression and it's boundary conditions are simply supported. For finite element analysis, the two node cubic Hermitian polynomials are utilized as shape Auctions. In order to illustrate the accuracy of this study, parameter studies for lateral buckling problems of circular arch are presented and compared with available solutions and numerical results analyzed by the FEM using straight beam element.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.22 no.50
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• pp.1-9
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• 1999

The purpose of this study is to establish a basis for assessing construct validity of measures used in organizational research. The classic Campbell and Fiske's(1959) criteria are found to be lacking in their assumptions, diagnostic information, and power. The inherent confounding of measurement error with systematic trait and method effects is a severe limitation for a proper interpretation of convergent and discriminant validity. The confirmatory factor analysis(CFA) approach overcomes most of the limitations found in Campbell and Fiske's(1959) method. However, the CFA approach confounds random error with unique variance specific to a measure. The second-order confirmatory factor analysis(SOCFA) was shown to harbor rather restrictive assumptions and is unlikely to be met in practice. The first-order, multiple-informant, multiple-item(FOMIMI) model is a viable option, but it may also be of limited use because of the large number measures.

• Smart Structures and Systems
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• v.26 no.3
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• pp.361-371
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• 2020

Exact solution for nonlinear behavior of clamped-clamped functionally graded (FG) buckled beams is presented. The effective material properties are considered to vary along the thickness direction according to exponential-law form. The in-plane inertia and damping are neglected, and hence the governing equations are reduced to a single nonlinear fourth-order partial-integral-differential equation. The von Kármán geometric nonlinearity has been considered in the formulation. Galerkin procedure is used to obtain a second order nonlinear ordinary equation with quadratic and cubic nonlinear terms. Based on the mode of the corresponding linear problem, which readily satisfy the boundary conditions, the frequencies for the nonlinear problem are obtained using the Jacobi elliptic functions. The effects of various parameters such as the Young's modulus ratio, the beam slenderness ratio, the vibration amplitude and the magnitude of axial load on the nonlinear behavior are examined.

• Korean Journal of Childcare and Education
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• v.14 no.4
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• pp.25-41
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• 2018

Objective: The purpose of this study was to examine the effects of parent-teacher relationships on mothers' parenting efficacy especially for toddlers. Methods: 225 mothers of toddlers completed questionnaires on parent-teacher relationships and parenting efficacy. This study used technical statistics, Pearson's correlation analysis, and multiple regression analysis in order to analyze the collected data. Results: First, there was a significant correlation between parent-teacher relationships and mothers' parenting efficacy. Second, the parent-teacher relationships was an important factor in predicting mothers' parenting efficacy. In particular, when a teacher and mother develop practical collaboration for caring for and educating a child, the mothers' parenting efficacy was higher. Conclusion/Implications: These findings indicate that the parent-teacher relationship is a significant factor in order to improve the quality of parenting. The results especially support the importance of collaboration between teachers and parents and suggest that we need to find practical ways for collaborating in the field. Limitations of this study and implications for future research were discussed.

• Bulletin of the Korean Chemical Society
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• v.10 no.5
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• pp.448-452
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• 1989

NADH analogs, 1-benzyl-3-substituted (X)-1,4-dihydropyridines 1-4 (1: X = $CONH_2$; 2: X = $CSNH_2$; 3: X = $COOCH_3$; 4: X = $COCH_3$) were synthesized. The second order rate constants for hydration reaction and oxidation reactions by $Cu^{2+}$, $Fe(CN)_6^{3-}$ or methylacridinium iodide (MAI) of the compounds were determined. For all reactions investigated, the rate constants increased with decreasing electronegative character of the 3-substituents of 1,4-dihydropyridines : the decreasing order of the reaction rates was 2>1>3>4. However, the sensitivity of the reaction rates on the 3-substituents differed among the reactions. This was explained in view of mechanisms of the reactions.

• Bulletin of the Korean Chemical Society
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• v.20 no.12
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• pp.1487-1492
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• 1999

The kinetics of oxidation of substituted styryl 4-biphenyl ketones and of substituted styryl 2-fluorenyl ketones by pyridinium chlorochromate (PCC) have been studied in 90% acetic acid- 10% water (v/v) containing perchloric acid and NaClO₄ at $10^0,\;20^0,\;30^0$ and 40℃. The reactions are first order in styryl ketones and PCC. The second order rate constants are well correlated only with σ$^+$ constants implying development of positive charge adjacent to benzene ring in the transition state. The effects of varying [HClO₄] and the percentage of acetic acid on the reactions have also been analysed. A mechanism involving nucleophilic attack of PCC leading to an unsymmetric intermediate from which epoxides are formed is proposed.

• Advances in environmental research
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• v.5 no.1
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• pp.37-50
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• 2016

The main objective of this study is to evaluate adsorptive removal of Methylene Blue (MB) dye from aqueous solution using pumice powder. The effects of pH, adsorption time, agitation speed, adsorbent dose, and dye concentrations on dye adsorption were investigated. Process kinetics and isotherm model constants were determined accordingly. The results showed that adsorbent dose, dye concentration and agitation speed are the important parameters on dye adsorption and the removal of MB did not significantly change by varying pH. A total adsorption process time of 60 min was observed to be sufficient to effectively remove 50 mg/L MB concentration. The MB adsorption data obeyed both pseudo first order and second order kinetic models. Adsorption of MB by pumice fitted well both Langmiur and Freundlich isotherms ($R^2{\geq}0.9700$), except for 150 rpm agitation speed that system fitted only Langmiur isotherm. The results of this study emphasize that pumice powder can be used as a low cost and effective adsorbent for dye removal.

• Journal of Family Resource Management and Policy Review
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• v.16 no.2
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• pp.1-18
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• 2012

This study analyzes the balance between work and family in married, working men and investigates their need to create this balance. Data from 253 married men was collected and analyzed. The index for the questionnaire was developed using the scale from the Second National Survey of Korean Families and related research. The results show that married, working men are slightly better at balancing their work and family lives than average. Furthermore, the effects of job-related variables were higher than the effects of other social-demographic variables. Job flexibility was the major variable that determined the balance between work and family. The highest need to balance between work and family was monetary support for caring and educating children. This paper concludes that in order to improve the work-family balance, the current working culture has to be changed, and various policies and strategies that encourage a family-friendly working culture must be implemented.

• Steel and Composite Structures
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• v.14 no.1
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• pp.1-20
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• 2013

This paper presents the formulation for a novel force-based 1-D compound-element that captures both material and second order P-${\Delta}$ nonlinearities in steel frames. At the nodal points, the element is attached to nonlinear rotational and a translational springs which represent the flexural and axial stiffness of the connections respectively. By decomposing the total strain in the material as well as the generalised displacements of the flexible connections to their elastic and inelastic components, a secant solution strategy based on a direct iterative scheme is introduced and the corresponding solution strategy is outlined. The strain and slope of the deformed element are assumed to be small; however the equilibrium equations are satisfied for the deformed element taking account of P-${\Delta}$ effects. The formulation accuracy and efficiency is verified by some numerical examples on the nonlinear static, cyclic and dynamic analysis of steel frames.

• Structural Engineering and Mechanics
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• v.36 no.1
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• pp.57-78
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• 2010

A novel flexibility-based 1D element that captures the material nonlinearity and second order P-$\Delta$ effects within a reinforced concrete frame member is developed. The formulation is developed for 2D planar frames in the modified fiber element framework but can readily be extended to 3D cases. The nonlinear behavior of concrete including cracking and crushing is taken into account through a modified hypo-elastic model. A parabolic and a constant shear stress distribution are used at section level to couple the normal and tangential tractions at material level. The lack of objectivity due to softening of concrete is addressed and objectivity of the response at the material level is attained by using a technique derived from the crack band approach. Finally the efficiency and accuracy of the formulation is compared with experimental results and is demonstrated by some numerical examples.