• Journal of the Semiconductor & Display Technology
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• v.6 no.4
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• pp.1-4
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• 2007

Carbon nanotube oscillators encapsulating copper nanowire were investigated by molecular dynamics simulations. The excess forces due to the carbon-carbon van der Waals interactions are higher than the excess force due to carbon-copper interactions. And the masses of copper atoms are higher than those of carbon atoms. So, the carbon atoms are easier accelerated than the copper atoms. When the encapsulated copper nanowire deforms the encapsulating nanotube, the frequency can not be estimated by the mass-frequency dependence in classical oscillation theory.

• Polymer(Korea)
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• v.25 no.1
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• pp.98-107
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• 2001

Dielectric properties and shape memory characteristics of SBS composites filled with carbon black as conductive filler and (Ba,Ca)$(Sn,Ti)O_3$ or $SrTiO_3$ as dielectrics were investigated for the development of phantom model. SBS/carbon black composite showed an increment of complex dielectric constant with increasing the content of carbon black and the frequency dependence that the dielectric constant decreases with the frequency. The complex dielectric constant and the conductivity of SBS/carbon black/dielectrics composites increased with the increase of dielectrics and the characteristics of the frequency dependence also occurred by the effect of carbon black. Phantom materials with the dielectric properties and the conductivity corresponding to human tissues for the measurement of specific absorption rate(SAR) within the frequency range of current mobile phones(775MHz~2GHz) could be developed by adjusting the composition ratios of carbon black, dielectrics and SBS and by controlling the characteristic of frequency dependence of composite. From thermomechanical cycling test good shape recoverability could be obtained in SBS composite even though the residual strain was increased by the effect of filler.

• Applied Microscopy
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• v.47 no.3
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• pp.121-125
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• 2017

This study deals the prediction of temperature effect on low-frequency dispersion of alternating current (AC) conductivity spectra of composite materials based on copolymer reinforced with carbon black (CB) particles. A sample of ethylene butylacrylate loaded with 13% of CB particles were prepared and investigated using the impedance spectroscopy representation in the frequency range from 40 Hz to 0.1 MHz and temperature range from $20^{\circ}C$ to $125^{\circ}C$. The dielectric constant, ${\varepsilon}^{\prime}$, and dielectric losses, ${\varepsilon}^{{\prime}{\prime}}$, were found to decrease with increasing frequency. The frequency dependence of the AC conductivity follows the universal power law with a large deviation in the high frequency region, the positive temperature coefficient in resistivity effect has been observed below the melting temperature which makes this composite potentially remarkable for industrial applications.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.2
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• pp.209-217
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• 2020

The purpose of this study was to compare the model-predicted and experimentally measured target strength (TS) of golden cuttlefish Sepia esculenta cuttlebones. Ultrasonic signals used to estimate frequency-dependent TS and the speed of sound in cuttlebones were measured by pulse-echo and through-transmission techniques, using a chirp sonar system and an ultrasonic pulser/receiver system under controlled laboratory conditions. The model appeared to slightly underestimate the predicted TS values in the frequency range of 100-160 kHz. However, there was good agreement between the predicted and measured TS values in the frequency range of 160-200 kHz. The significant similarity between the model-predicted and experimentally measured TS values supports the use of the Kirchhoff-ray mode (KRM) model for acoustic scattering analysis of cuttlebones. Accordingly, we concluded that the KRM model can be used as a tool to evaluate the frequency-dependent variability of TS due to changes in golden cuttlefish swimming depth.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.550-553
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• 2001

In this study, unity current gain frequency f$\_$T/ of GaAs MESFET is predicted with different temperatures up to 400 $^{\circ}C$. Temperature dependence parameters of the device including intrinsic carrier concentration n$\_$i/ effective mass, depletion width are considered to be temperature dependent. Small signal parameters such as gate-source, gate dran capacitances C$\_$gs/ C$\_$gd/ are correlated with transconductance g$\_$m/ to predict the unity current gain frequency. The extrinsic capacitance which plays an important roles in high frequency region has been taken into consideration in evaluating total capacitance by using elliptic integral through the substrate. From the results, f$\_$T/ decreases as the temperature increases due to the increase of small signal capacitances and the mobility degradation. Finally the extrinsic elements of capacitances have been proved to be critical in deciding f$\_$T/ which are originated from the design rule of the device.

• Current Optics and Photonics
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• v.7 no.1
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• pp.28-32
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• 2023

Frequency characteristics of gain-saturated erbium-doped fiber amplifier (EDFA) are experimentally evaluated to mitigate the optical signal fluctuation induced by atmospheric turbulence in terrestrial freespace optical communication systems. Here, an acousto-optic modulator (AOM) is used to emulate optical signal fluctuations induced by atmospheric turbulence. The waveform which is generated in proportion to the refractive-index structural parameters is used to drive the AOM at various periodic frequencies. Thus, the dependence of the signal fluctuation suppression on the frequency is evaluated. The experiment is conducted using a periodic frequency sweep of the AOM driving voltage waveform and signal input power variation of the amplifier. It is observed that a low periodic frequency and high input signal power effectively suppress the optical signal fluctuation. This study evaluates the experimental results from the high-pass filter and gain-saturation characteristics of the EDFA.

• Proceedings of the Korean Magnestics Society Conference
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• 2007.05a
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• pp.143.2-143.2
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• 2007

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1988.10a
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• pp.12-13
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• 1988

• Korean Journal of Human Ecology
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• v.5 no.2
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• pp.131-143
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• 1996

The purpose of this study was to investigate clothing involvement and clothing behavior of women and to indentify the relationship between clothing behavior and clothing involvement. The data were analyzed using percentage, frequency, factor analysis, ANOVA, Scheffe test, t-test, and Multiple Regression. The results of the study were as follows: 1. Five dimensions of clothing involvement were derived by factor analysis such as fashion, interest pleasure, symbolism, and perceived buying risk. 2. There were significant relationships between clothing involvement dimensions and demographic characteristics such as age, educational background and family income level. Those who were younger and not married showed positive relationship among fashion, interest and pleasure of clothing involvement dimensions. Those who had higher educational background showed positive relationship with clothing involvement. Those who were empolyed showed higher clothing involvement with symbolism and perceived buying risk. 3. Age, marital status, and educational background showed important variables as factors that exert influence on clothing behavior: Those who were younger and not married attached importance to interest aesthetics, psychological dependence, and fashion. Those who were older and married attached importance to modesty and comfort. The more educated respondents were more concerned about interest aesthetics, symbolism, psychological dependence, and fashion. 4. The fashion of clothing involvement showed positive relationship in fashion, interest, symbolism, and psychological dependence of clothing behavior, and negative relationship in modesty and comfort. The interest of clothing involvement showed positive relationship in aesthetics and interest, and negative relationship in modesty and comfort of clothing behavior. The pleasure of clothing involvement showed positive relationship in psychological dependence, management, interest, and pleasure of clothing behavior. The symbolism of clothing involvement showed positive relationship in symbolism, modesty, conformity, psychological dependence, and fashion of clothing behavior. The perceived buying risk of clothing involvement showed positive relationship in management, conformity, and comfort and negative relationship in symbolism and fashion of clothing behavior.

• Journal of Industrial Convergence
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• v.22 no.6
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• pp.61-71
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• 2024

The study aimed to examine the mediating effect of ego resiliency and smartphone dependence in the relationship between children's attachment to mother and happiness. For the purpose, 1,143 research subjects were selected from the 12th data of the Korean Children's Panel surveyed by the Korea Institute of Child Care and Education. As for the analysis methods, frequency analysis, descriptive statistics analysis, and correlation analysis were executed, while the mediating effect was analyzed by applying Process Macro Model Number 4 analysis. The indirect effect of ego resiliency and smartphone dependence were verified by using boot-strapping. The findings are as follows. First, children's attachment to mother was found to increase their happiness. Second, ego-resilience was shown to play a partial mediating role in the relationship between children's attachment to mother and happiness. Third, the effect of children's attachment to mother on happiness was partially mediated by smartphone dependence. Based on the results, the study suggested the various practical programs to improve children's happiness.