• Journal of the Korean Ceramic Society
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• v.50 no.1
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• pp.70-74
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• 2013

Dependence of microwave dielectric properties on the crystallization behaviors of $CaMgSi_2O_6$ (diopside) glass-ceramics was investigated with different heat treatment methods (one and/or two-step). The crystallization behaviors of the specimens, crystallite size and degree of crystallization, were evaluated by differential thermal analysis (DTA), scanning electron microscope (SEM) and X-ray diffraction (XRD) analysis by combined Rietveld and reference intensity ratio (RIR) methods. With an increase in heattreatment temperature, the dielectric constant (K) and the quality factor (Qf) increased due to the increase of the crystallite size and degree of crystallization. The specimens heat-treated by the two-step method had a higher degree of crystallization than the specimens heat-treated by the one-step method, which induced improvement in the quality factor (Qf) of the specimens.

• Journal of the Optical Society of Korea
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• v.20 no.4
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• pp.524-529
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• 2016

Diagnostic sensors are demanded during plasma processes. Holograms of plasma taken with laser light without a reference beam were used to monitor behaviors of charged particles produced in nitrogen plasma as a function of electrode temperature ranging between 50 and 300℃. Holograms were characterized as a function of the pixel sum and grayscale value. Pixel sum calculated in identified grayscale ranges strongly correlated with ion density and emitted light intensity measured with a langmuir probe and optical emission spectroscopy, respectively. The performance was further evaluated with data acquired as a function of N₂ and NH₃ flow rates and improved correlations were observed in the new grayscale range. The confirmed correlations indicate that a hologram is a viable means to diagnose behaviors of plasma particles such as ions. Underlying principles are discussed in view of particle and charge composing vacuum and light.

• Korean Journal of Childcare and Education
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• v.14 no.5
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• pp.65-84
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• 2018

Objective: This study investigated the effects of discussion using personality picture books on young children's self-regulation ability and pro-social behaviors. Methods: Participants consisted of thirty-nine 5-year-old children who were going to a kindergarten in Gwangju metropolitan city. Nineteen children belonged to the experimental group and twenty children to the comparative group. The experimental group carried out discussion using personality picture books, and the comparative group carried out conversation activities. Results: The results of this study demonstrated that the experimental group scored higher than the comparative group in self-regulation ability and pro-social behaviors. That is to say, the experimental group scored higher than the comparative group in three sub factors of self-regulation ability and seven sub factors of pro-social behaviors. Conclusion/Implications: It is significant that this study provides useful information about discussion using personality picture books with young children that can be used in the early childhood field.

• Journal of Environmental Health Sciences
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• v.45 no.6
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• pp.613-621
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• 2019

Objectives: This study was performed to examine the relationship between health behaviors, living environment, and asthma in adolescents in Korea. Methods: Information on adolescents' characteristics, including demographic factors, health behaviors, and doctor's diagnosis of asthma was obtained from the Korean Youth Risk Behavior Web-based Survey (2015). In total, 68,043 middle and high school students participated. Environmental characteristics, including city park area and outdoor PM₁₀ concentrations in 2015 were obtained from the Korean Statistical Information Service. The adolescents' and environmental characteristics were merged by local information. Multiple logistic regression models were used to investigate the risk factors affecting asthma in adolescents. Results: The prevalence of asthma in adolescents in 2015 was 8.8%. In the multiple logistic regression analysis, adolescents who were male, attended middle school, suffered obesity, experienced tobacco smoking, had physical activity levels of 2 to 4 days, had higher stress levels, and lived in areas with outdoor PM₁₀ concentrations more than 47 ㎍/㎥ were more likely to have asthma, while adolescents who had middle levels of family economic status were less likely to do so. Conclusions: The fact that PM₁₀ concentration can affect asthma is an important point in this study. Risk factors identified in this study could be used as basic data for the prevention and management of asthma in Korea.

• Journal of the Korean Ceramic Society
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• v.39 no.6
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• pp.528-534
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• 2002

CaO ceramics were prepared by conventional sintering process and their hydration behaviors were evaluated by measuring weight increment on saturated water vapor pressure at ambient temperature. CaCO$_3$ and limestone were used as CaO source materials and $Al_2$O$_3$, MgO and SiO$_2$ were added as sintering agents. $Al_2$O$_3$ was a liquid phase sintering agent to increase densification and grain growth rates, whereas MgO and SiO$_2$, densification and grain growth inhibitors. Regardless of composition, all of the prepared CaO ceramics showed the improved hydration resistance as bulk density increased. Especially, when bulk density was more than 3.0 g/㎤, there was no weight increment after 120 h of hydration. Therefore, to decrease contact area between CaO and water vapor by increasing bulk density with the $Al_2$O$_3$ sintering additive was effective for the improvement of CaO hydration resistance.

• Transactions on Electrical and Electronic Materials
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• v.11 no.6
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• pp.275-278
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• 2010

We have examined the Ferroelectric properties of $PbZr_{0.4}Ti_{0.6}O_3$ (PZT) grains by monitoring the surface potential through the utilization of Kelvin force microscopy. Hysteretic and time dependent behaviors of small and large grains were compared with each other. The smaller grain yields had smaller values of surface potential. However, the normalized voltage versus surface potential behavior indicates that the smaller grains became saturated earlier with respect to the writing voltages than did the larger grains. On the other hand, the surface potential hysteresis loop obtained from the smaller grains showed a similar shape to what might be obtained from a Zr rich PZT film. In contrast the hysteresis loop of the larger grain looks like that obtained from a Ti-rich film. In addition, the time dependent behaviors of the smaller grains also revealed a better response than the response of larger grains. The overall ferroelectric properties of the smaller grains seem better than corresponding properties for larger grains. The Ti/Zr ratio of the PZT film which was examined in this study was 60/40.

• Journal of Magnetics
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• v.21 no.2
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• pp.235-238
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• 2016

Microstructure and magnetization behaviors of $MnBi/Fe_3B/Nd2_Fe_{14}B$ nanocomposite alloy have been investigated. It was found that the coercivity increased firstly and then decreased, and saturation magnetization decreased with the additon of MnBi alloy. The addition of 40 wt.% MnBi powder enhanced the coercivity from 192.8 kA/m to 311.2 kA/m. The ${\delta}M$ and D(H)-H plots suggested the occurrence of a stronger exchange-coupling occurring between the hard and soft magnetic phase for this sample. The dependence of coercivity with temperature was discussed in 40 wt.% $Mn_{55}Bi_{45}$/ 60 wt.% $Nd_{4.5}Fe_{76.5}Nb_{0.5}B_{18.5}$ alloy powder, and a positive temperature coefficient was founded from 298 K to 350 K.

• Advances in nano research
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• v.1 no.4
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• pp.193-202
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• 2013

In this article, we present the effects of Ag doping and after-growth thermal annealing on the photoluminescence (PL) and thermoluminescence (TL) behaviors of $SnO_2$ nanoparticles. $SnO_2$ nanoparticles of 4-7 nm size range containing different Ag contents were synthesized by hydrothermal process. It has been observed that the after-growth thermal annealing process enhances the crystallite size and stabilizes the TL emissions of $SnO_2$ nanostructures. Incorporated Ag probably occupies the interstitial sites of the $SnO_2$ lattice, affecting drastically their emission behaviors on thermal annealing. Both the TL response and dose-linearity of the $SnO_2$ nanoparticles improve on 1.0% Ag doping, and subsequent thermal annealing. However, a higher Ag content causes the formation of Ag clusters, reducing both the TL and PL responses of the nanoparticles.

• Proceedings of the Safety Management and Science Conference
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• 2011.04a
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• pp.635-643
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• 2011

The purpose of this study was to examine the effects of goal-setting on Eco-driving behaviors. An additional purpose was to examine whether setting goals on target behaviors has spread effects on non-target Eco-driving behaviors. Three office workers who drive regularly participated in this study. An AB multiple baseline design was adopted. After baseline (A), participants set goals on two or three target behaviors(e.g., over speeding, put the gears in neutral, extreme acceleration) (B). Results showed that goal-setting was effective in increasing the targeted Eco-driving behaviors. In Addition, most of the non-target Eco-driving behaviors(e.g., extreme break, extreme acceleration) increased.

• Journal of the Korean Society of Safety
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• v.26 no.6
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• pp.124-129
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• 2011

The purpose of this study was to examine the effects of goal-setting on Eco-driving behaviors. An additional purpose was to examine whether setting goals on target behaviors had spread effects on non-target eco-driving behaviors. Three office workers who drive regularly participated in this study. An AB multiple baseline design was adopted. After baseline (A), participants set goals on two or three target behaviors(e.g., over speeding, put the gears in neutral, extreme acceleration) (B). Results showed that goal-setting was effective in increasing the targeted eco-driving behaviors. In addition, most of the non-target eco-driving behaviors(e.g., extreme break, extreme acceleration) increased.