• Journal of the Korean Society for Precision Engineering
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• v.14 no.10
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• pp.164-169
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• 1997

The aim of this paper is to present some results of sensitivity analysis in frequency domain. The sensitivity fonctions in frequency domain is not depend on the external excitation but depend on the frequency of the system's resonance. The sensitivity functions are determined as function of partial derivatives of system transfer functions taken with respect to system design parameters. The logarithmic sensitivity function is the dimensionless sensitivity funciton available, making it useful to compare the influence of various parameters on system variables. Two degree of fredom system is used to illustrate the procedure for sensitivity analysis proposed in this paper.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.11
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• pp.42-47
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• 2007

In this paper, influence of lossy ground and gap variation between lossy ground and UWB antenna on impulse propagation in time domain for impulse ground penetrating radar (GPR) is numerically and experimentally investigated. For this study, a novel planar UWB fat dipole antenna is developed. First, influence of lossy ground and gap variation between lossy ground and UWB antenna is simulated. For verification, a test field of sand and wet clay soil is built and using the developed dipole antenna, transmission behavior is investigated at the test field. With an aid of IDFT (inverse discrete Fourier transform), time domain impulse response for transmission coefficient measured and simulated in frequency domain is obtained. Measurement and simulation show that the frequency of maximum transmission coefficient and transmission coefficient are increased with higher dielectric constant and larger gap distance. In time domain, it is shown that for higher dielectric constant, the amplitude of the received signal in time domain is higher and reflected signals are seriously modified. Also, it is found that variation of gap between antenna and ground surface makes timing of peak value changed.

• Korean Journal of Child Studies
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• v.35 no.2
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• pp.1-23
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• 2014

The purpose of this research was to investigate the most critical variables in the school adjustment of youth. In addition, this research assessed the impact of variables according to the categorization of individual, family, and school domains. To acquire the effect sizes, published studies between 1990 and 2012 were reviewed systematically and synthesized by meta-analysis. The major findings were as follows. First, this study identified a total of 34 variables which can have an influence on the school adjustment of youth and confirmed that 24 of those variables are significant. The most crucial variable that can influence school adjustment is that of a teacher's support. The next most important variables are self-resilience, relationships with friends, and self-efficiency. Focusing on the categorized elements, self-resilience is the most critical variable in the individual domain, the parent-child relation is the most crucial variable in the family domain, and a teacher's support is the most powerful variable in the school domain. Based on these results, this study suggested a number of the indispensable components in interventions to improve the youth's adjustment in school.

• Journal of Ocean Engineering and Technology
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• v.32 no.5
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• pp.333-340
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• 2018

This paper addresses the concept of the representative mean position, which was devised to improve the numerical efficiency of a time domain fatigue analysis of a mooring chain. To investigate the influence of an artificial offset of the floater on the fatigue of the mooring chain, a parametric study was performed on the moored FPSO under various combinations of offsets and environmental conditions. Tension time histories were calculated using the de-coupled analysis method, and fatigue damages were calculated to determine the influence of the offset. The parametric study was extended to a more realistic case to determine the actual effect of the representative mean position, where a comparison was made between the two different analysis results, one using the representative mean position and the other one using the actual mean position. It was confirmed that the application of the representative mean position guaranteed the conservatism of the fatigue damage with the enhanced numerical efficiency in the time domain fatigue analysis.

• Nano
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• v.13 no.12
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• pp.1850149.1-1850149.10
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• 2018

Ferroelectric particles have been applied in the photocatalytic field because the spontaneous polarization results in the internal electric field, which can accelerate the separation and migration of photogenerated carriers. In this study, the $BaTiO_3$ (BT) fibers are synthesized by electrospinning. The BT fibers calcined above $800^{\circ}C$ exhibit a strong ferroelectric property, which is verified by a typical butterfly-shaped displacement-voltage loop. It is found that the BT fibers with the single-domain structure exhibit better photocatalytic performance than that with the multi-domain configuration. When the single-domain transforms into multi-domain, the integrated internal electric field correspondingly breaks up, inducing that the internal electric field might cancel each other out and diminish the separation of photogenerated carriers. Also, the Au nanoparticles can improve the photocatalytic activity further on account of the surface plasmon resonance. Therefore, it is suggested that Au nanoparticles decorated on ferroelectric BT nanomaterials are promising photocatalysts.

• Journal of the Korean Society for Precision Engineering
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• v.9 no.1
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• pp.126-136
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• 1992

In this paper, a simple structured feedback compensation scheme for a electro-hydraulic servo system to keep the response characteristics unchanged regardless of the load variation is proposed. In electro-hydraulic servo system, servovalve is most important control element. But the relation between input corrent and output flowrate of the servovalve has properties as follows; firstly, in spite of constant input current, output flowrate decreases as load pressure increases, secondly, according to frequency response of typical servovalve, the characteristics of gain and phase shift is something like 2'nd order system. Load pressure feedback compensation method has been applied to eliminate the first influence, the second influence has been improved by phase lead compensation method. As a result of above compensation methods, regardless of variation load condition, spring and inertia load, the compensation scheme has been verified to be effective within the range of frequency less than 25Hz by static response and dynamic response in time domain and frequency domain through experiments.

• Structural Engineering and Mechanics
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• v.31 no.6
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• pp.717-735
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• 2009

The present problem is concerned with the study of deformation of micropolar thermoelastic medium with voids under the influence of various sources acting on the plane surface. The analytic expressions of displacement components, force stress, couple stress, change in volume fraction field and temperature distribution are obtained in the transformed domain for Lord-Shulman (L-S) theory of thermoelasticity after applying the integral transforms. A numerical inversion technique has been applied to obtain the solution in the physical domain. The numerical results are presented graphically. Some useful particular cases have also been deduced.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.357-364
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• 2006

The meshfree method is extended by the local partition of unity method to model the cohesive cracks in two dimensional continuum The shape function of a particle whose domain of influence is completely cut by a crack is enriched by the step enrichment function. If the domain of influence contains a crack tip inside, it is enriched by the branch enrichment function without the stress singularity. It is found that this method is more accurate and converges faster than the meshless methods for LEFM cracks based on the visibility concept Several staic and dynamic examples are solved to verify the method.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.507-512
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• 2007

A new type of extended element-free Galerkin method (XFEM) is proposed on this paper. The blending region which was inevitable in the extended finite element method and the extended meshfree method is removed in this method. For this end, two different techniques are developed. The first one is the modification of the domain of influence so that the crack tip is always placed on the edge of a domain of influence. The second method is the use of the Lagrange multiplier. The crack is virtually extended beyond the actual crack tip. The virtual extension was forced close by the Lagrange multiplier. The first method can be applied to two dimensional problems only Lagrange multiplier method can be used in both two and three dimensions.

• Journal of Families and Better Life
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• v.9 no.2
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• pp.191-207
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• 1991

The purpose of this study is to investigate the degree of socialization of household work and to analyze the influence of demographic and psycho-social variable on socialization of household work. For the purpose of this study, questionnaires were administrated to 314 housewives in Pusan. For the statistical analysis were as follows; 1)The degree of socialization in the domain of food showed significant difference by number of family, number of children, housewife's age, housewife's education, husband's education, income and sex-role attitude. The degree of socialization in the domain of housing showed significant difference by family pattern, housewife's education, husband's education, state of housewife employment. husband's occupation , income and sex-role attitude. The degree of socialization in the domain of clothing showed significant difference by housewife's age, housewife's education, husband's education , state of housewife employment. husband's occupation, income and sex-role attitude. The degree of socialization in the domain of family management showed significant difference by number of children, housewife's age. state of housewife employment, income, period of marriage life and sex-role attitude. The degree of socialization in the domain of home management showed significant difference by housewife's education, husband's occupation, sex-role attitude and share of household work. 2) The socialization in the domain of food was influenced husband's education, income, housewife's education and sex-role attitude. The socialization in the domain of housing was influenced husband's education, income, housewife's occupation and sex-role attitude. The socialization in the domain of clothing was influenced husband's education, income. housewife's occupation and sex-role attitude. The socialization in the domain of family management was influenced husband's education, shave of household work. and sex-role attitude. The socialization in the domain of home management was influenced husband's education, shave of household work, and sex-role attitude.