• Journal of the Korean Applied Science and Technology
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• v.34 no.4
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• pp.705-716
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• 2017

In this study, Indium-Titanium hydroxide particle with 0.5, 1.0, 1.5 wt% of $TiO_2$ were synthesized by sol process and adding the base, ITiO(Indium Titanium Oxide) particles were obtained by gelling at $200^{\circ}C$ and $500^{\circ}C$. The ITiO particle's size with gel process at $200^{\circ}C$ was smaller than ITiO particle's size with gel process $500^{\circ}C$. The ITiO particle with gel process at $200^{\circ}C$ was used to fabricate dense ITiO target. ITiO targets with 0.5, 1.0, 1.5 wt% of $TiO_2$ were fabricated and used to obtain ITiO thin films onto glass by sputtering. Among those sputtered ITiOs' thin films, ITiO thin film with 0.4 % of $O_2$ and 0.5 wt% of $TiO_2$ showed the lowest specific resistance, highest charge mobility and lowest carrier concentration. It was found the light transmittance of the ITiO film were increased highly compared to light transmittance of ITO (Indium Tin Oxide) thin film over Infrared wavelength ranges.

• Herbal Formula Science
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• v.31 no.4
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• pp.215-230
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• 2023

Objectives : Schisandra chinensis (Turcz.) Baill contains many nutrients and exhibits high physiological functions. It has been shown that Schisandra seed and pamace contains more nutrients than fruits and thus have higher antioxidant efficacy. In this study, seed and pamace of Schisandra chinensis (Turcz.) Baill (SPSC) were treated with hot-melt extrudate (HME) extrusion to produce water-soluble nanoparticles. Methods : SPSC was treated with HME to prepare nanoparticles. In this process, excipients (hydroxypropyl methylcellulose, pullulan, 2-hydroxylpropyl-beta-cyclodextrin, lecithin) were added to prepare a hydrophilic polymer matrix. To compare and analyze the antioxidant effect and schizandrin content, total flavonoid content, total phenol content and ABTS assay were measured. To confirm the effect of increasing the water solubility of the particles, particle size and water solubility index measurements were performed. The molecular of the material was analyzed using Fourier transform infrared spectroscopy (FT-IR). Results : The particle size of HME extrudates decreased, while total phenols, flavonoids, schizandrin, antioxidant effect, and solubility increased. Through FT-IR, it was confirmed that the SPSC and the extrudate exhibit the same chemical properties. In addition, it was confirmed that when extracted with water, it exhibited a higher antioxidant effect than the ethanol extract. Conclusions : HME technology increased the solubility of SPSC, which are processing by-products, and improved their antioxidant effect to a higher degree. It was confirmed that SPSC could be used as an eco-friendly, high value-added material.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.6 no.6
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• pp.457-460
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• 2005

Nano-sized titanium oxide and zirconium oxide powders were synthesized by hydrolysis of titanium isopropoxide $[Ti(OC_3H7)_4]$ and zirconium tetrachloride ($ZrC1_4$) via a sol-gel technique. Lead titanate powders were prepared by mixing $TiO_2$ precursors with PbO slurry made with dilute $NH_4OH$. Lead zirconate titanate powders were, then, synthesized by mixing $PbTiO_3$ with $ZrO_2$ powders. The goal of this research was to obtain the $PbZrTiO_3(PZT)$ powders and sintering these powders at low temperature. The $PbTiO_3$ and PZT powders after firing were analyzed by X-ray diffraction(XRD) and transmission electron microscopy(TEM) was utilized to observe the shape and size of the synthesized nano-particles. In the XRD pattern, the well-crystallized PZT phase could be obtained in consequence of firing at $900^{\circ}C$. SEM micrographs also showed that grains of PZT were relatively well grown with the size of the range of $2{\~}4{\mu}m$. The densified perovskite structure of $PbZrTiO_3$ could be obtained by sintering at temperature as low as $900^{\circ}C$. Characterization of the samples showed improved piezoelectric properties.

• Journal of the Korean Ceramic Society
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• v.41 no.4
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• pp.284-288
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• 2004

To improve mechanical properties of $Al_2$O$_3$/ZrO$_2$composites have been controlled dispersion of ultra low size ZrO$_2$ particles in $Al_2$O$_3$ ceramics by polymeric precursor method (Pechini process). In case of coprecipitation or mechanical mixing of ZrO$_2$ powders with $Al_2$O$_3$, homogeneous dispersion and controlling the ZrO$_2$ size were relatively difficult due to high sintering temperature. So the polyesterization process of Zr/Y(NO$_3$)$_3$-citric acid solution in ethylene glycol with the commercial sub-micron sized o(-alumina powder (Sumitomo AES-11(0.4 ${\mu}{\textrm}{m}$)) was adopted in order to obtain homogeneous dispersion of ZrO$_2$ in A1203. By this partial polyesterization process, the homogeneous dispersion of relatively low sized ZrO$_2$in $Al_2$O$_3$/ZrO$_2$composites was achieved at 1450∼1$600^{\circ}C$ of sintering temperature range and their mechanical properties were measured.

• Journal of Bio-Environment Control
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• v.12 no.1
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• pp.12-16
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• 2003

The effect of humidifying methods on the mean size of droplets ejected from humidifier and distributions of relative humidity in a graft-taking enhancement system (GTES) was investigated. The mean sizes of droplets ejected from an ultrasonic humidifier and a steam humidifier with electrodes were 7.58$\pm$0.14 and 9.01$\pm$0.06 $\mu$m, respectively. Assuming that the particles ejected from humidifiers were mutually combined with distance, the mean diameter of droplets became larger as the distance apart from the outlet of humidifiers increased. When the relative humidity in GRS was controlled at 90％ using the ultrasonic humidifiers, the average relative humidity at the height of 0.4, 1.1 and 1.8 m were 92.1$\pm$5.3, 90.9$\pm$5.6, and 89.7$\pm$6.8%, respectively. However, the average relative humidity using the steam humidifier with electrodes showed 93.4 $\pm$5.4, 90.7$\pm$5.9, and 89.3$\pm$7.0%, respectively. Therefore, it was concluded that humidification by ultrasonic humidifier would be appropriate for the uniform distribution of relative humidity in GTES.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.4
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• pp.359-366
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• 2022

In this paper, the effect of compression levels on the strengths of porous concrete using bottom ash aggregates was analyzed. Coal bottom ash (CBA) was used as aggregate in porous concrete in this study. The aggregate size types used in the CBA concrete mixtures were catagorized into two different ones. One included only a single aggregate particle size and the other included hybrid aggregate particles mixed at a ratio of 8:2 volume proportion. The water-binder ratio was fixed at 0.30, and the compression levels were applied at 0.5, 1.5, and 3.0 MPa valu es to fabricate a porou s concrete specimen. The total porosity, compressive, splitting tensile, and flexural tensile strengths were tested and analyzed. When the compression level increased, the total porosity decreased, meanwhile the compressive, split tensile, and flexural tensile strengths increased. The total porosity of concrete using hybrid aggregate was lower and the strength was larger than those of concrete using single-type aggregate. Finally, the correlation between the total porosity, compressive, split tensile, and flexural tensile strengths of porous concrete were presented. The total porosity and strength characteristics showed an inversely proportional correlation.

• Journal of the Korea Organic Resources Recycling Association
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• v.29 no.4
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• pp.47-54
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• 2021

In this study, the performance of a honeycomb-type hydrogen oxidation catalyst to remove hydrogen in a hydrogen economy society to secure leaking hydrogen. The Pd/TiO₂ catalyst was prepared based on a liquid phase reduction method that is not exposed to a heat source, and it was showed through H₂-chemisorption analysis that it existed as very small active particles of 2~4 nm. In addition, it was found that the metal dispersion decreased and the active particle size increased as the reduction reaction temperature increased. It was meant that the active metal particle size and the hydrogen oxidation performance were in a proportional correlation, so that it was consistent with the hydrogen oxidation performance reduction result. The prepared catalyst was coated on a support in the form of a honeycomb so that it could be applied to the hydrogen industrial process. When 20 wt% or more of the AS-40 binder was coated, oxidation performance of 90% or more was observed under low-concentration hydrogen conditions. It was showed through SEM analysis that long-term catalytic activity can be expected by enhancing the adhesion strength of the catalyst and preventing catalyst desorption. It is a basic research that can secure safety in a hydrogen society such as gasification, organic resource, and it can be utilized as a system that can respond to unexpected safety accidents in the future.

• Journal of Korea Multimedia Society
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• v.8 no.4
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• pp.554-568
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• 2005

We suggest the dynamic stroke generation algorithm that provides frame-to-frame coherence in 3D non-photorealistic animations. We use 3D particle system to eliminate the visual popping effect in the animated scene. Since we have located particles on the 3D object's surface, the coherence is maintained when the object or the camera is moving in the scene. Also, this algorithm maintains the coherence when camera is zooming in/out. However, the brush strokes on the surface also zoom in/out. This result(too large or too small brush strokes) can not represent hand-crafted brush strokes. To remove this problem, we suggest stroke generation algorithm that dynamically maintains the number of brush stroke and its size during camera zoom in/out.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.6
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• pp.447-452
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• 2011

In this study, the polymeric membrane module is used as a diffuser and an image analysis technique based on visual information is applied to get bubble characteristics. The bubble size generated passed through polymeric membrane module was smaller from 30 to 64% than that of air stone, and bubble volume over 70% was ranged from 0.2 to 0.82 mm. But over 80% the bubbles from air stone diffuser ranged from 0.77 to 1.08 mm. The air stone and polymeric membrane module used as diffuser for a flotation system. The floc size inside the flotation reactor using air stone diffuser was bigger than that of the polymeric membrane module, which means that the micro-bubbles generated from polymeric membrane module could provide better opportunities for collisions between colloidal particles than those from air stone diffuser. Therefore, there is a possibility to apply the polymeric membrane module as a diffuser to increase the removal efficiency in the flotation process. Also, the image analysis technique used in this study could be applied as a useful analytical tool for acquisition of an information about the bubble characteristic.

• Journal of the Korean Electrochemical Society
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• v.10 no.1
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• pp.48-51
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• 2007

In order to investigate the effects of particle size and specific surface area(BET area) of spinel powder, $LiMn_2O_4$ were synthesized using metal oxide precursor by co-precipitation method(CoP) and solid state reaction (SSR) .X-ray diffraction(XRD) patterns revealed that the both prepared powder has a well developed spinel structure with Fd3m space group. The $LiMn_2O_4$ prepared by co-precipitation showed spherical morphology with narrow size distribution. However, the $LiMn_2O_4$ prepared by solid state reaction showed relatively smaller particles with irregular shape. The measured BET areas of the powers are $0.8m^2g^{-1}$ (CoP) and $3.6m^2g^{-1}$(SSR). The electrochemical performance of the Prepared $LiMn_2O_4$ powders was evaluated using coin type cells(CR2032) at elevated temperature ($55^{\circ}C$). The $LiMn_2O_4$ prepared by co-precipitation showed the better cycling performance(82.3%capacity retention at $50^{th}$ cycle) than that of the $LiMn_2O_4$(68.3%) prepared by solid state reaction at elevated temperature.