• Journal of the Microelectronics and Packaging Society
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• v.11 no.4 s.33
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• pp.55-59
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• 2004

We fabricates the $TiO_2$ thin film from anatase phase $TiO_2$ powder having good photocatalytic property using aerosol deposition method at room temperature. Aerosol deposition method, which sprays an aerosol powder with ultrasonic velocity and deposits a thin film on substrate at low temperature, has the advantages of low thermal stress and low cost. To fabricate the $TiO_2$ thin film, the aerosol bath pressure and chamber pressure were 500 torr and 0.4 torr, respectively. The difference of aerosol bath pressure and chamber pressure accelerated the $TiO_2$ nano powder to ultrasonic velocity through the nozzle of $0.4 mm{\times}10 mm$ and $TiO_2$ thin film was finally formed. SS mesh with diameter of 50 mm was used as a substrate to apply the $TiO_2$ thin film to water quality purification. The raw powder was dehydrated for the good dispersion of $TiO_2$ powder. To suppress the formation of second particle, the powder was dispersed for 90 min in alcohol bath by ultrasonic treatment and desiccated. The grain size of $1 {\mu}m$ was observed in $TiO_2$ thin film deposited on SUS mesh by scanning electron microscopy (SEM). The anatase phase of $TiO_2$ thin film was also observed by X-ray diffraction (XRD) and the anatase phase of raw powder was nicely maintained after aerosol deposition. The results are applicable to water treatment filter having photocatalytic reaction.

• Journal of the Korean Applied Science and Technology
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• v.37 no.5
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• pp.1159-1170
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• 2020

In this study, to improve the stability of fermented squalene developed using microorganisms, Microsome-SQ20 was prepared, and its physical behavior, properties, and efficacy were studied. The appearance of Microsome-SQ20 was a transparent liquid, no smell, and had a specific smell. The color was a transparent liquid, and the specific gravity was 0.928 and the pH was 5.82 (20% solution), forming a nano-emulsion suitable for use in cosmetics. It was confirmed that the content of the main component of squalene was 20.05%, which was stably sealed. The particle size measured by 0.1% aqueous solution of Microsome-SQ20 was 134.8 nm to obtain a bluish emulsified phase. The antioxidant effects of F-SQ and MF-SQ by DPPH radicals were 80.72% and 81.5%, respectively, showing superior effects compared to L-ascorbic acid. The cell viability of squalene (SQ), fermented squalene (F-SQ) and microsome squalene (MF-SQ) was at 10 ppm, respectively, showing 121.2%, 150.3%, and 129.9% cell viability. It was found that SQ, F-SQ, and MF-SQ had an elastase inhibitory ability of 8.7%, 10.33% and 8.7% at 10 ppm, respectively. In addition, the inhibitory ability of MMP-1 was 1.55%, 41.44%, 31.79% at 10 ppm for SQ, F-SQ, and MF-SQ, respectively, indicating that F-SQ significantly reduced the MMP-1 expression.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.8
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• pp.765-772
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• 2015

Cast iron is widely used in fields such as the transport and heavy industries. For parts where contact damage is expected to occur, it is necessary to understand the friction and wear characteristics of cast iron. In this study, we use cast iron plates as the specimens to investigate their friction and wear characteristics. We perform various experiments using a reciprocating type tribotester. We assess the frictional characteristics by analyzing the friction coefficient values that were obtained during the sliding tests. We observe the wear surfaces of cast iron and steel balls using a scanning electron microscope, confocal microscope, and 3d profiler. We investigate the friction and wear characteristics of cast iron by injecting sand and alumina particles having various sizes. Furthermore, we estimate the effect of temperature on the friction and wear characteristics. The results obtained are expected to aid in the understanding of the tribological characteristics of cast iron in industry.

• Journal of Oral Medicine and Pain
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• v.34 no.1
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• pp.39-48
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• 2009

Recently there is much interest in the antibacterial activity of nano-sized silver particle (nanosilver) since silver is known to be safe and effective as disinfectant for a long time. Oral malodor is considered to originate in the oral cavity primarily as a result of production of malodorous compounds by oral bacteria. Major compounds responsible for oral malodor are volatile sulfur compounds, which is thought to be generated by the G(-) anaerobic bacteria found normally in the oral cavity, especially on the dorsum of the tongue. The purposes of this study were to investigate the effect of nanosilver on growth of oral malodor generating microorganisms, including Fusobacterium nucleatum, Prevotella melaninogenica, Klebsiella pneumonia, and to determine the optimal culture condition of them. The results were as follows: 1. The optimal culture condition for P. melaninogenica was vacuum culture using desiccator after evacuation of air by vacuum pump in chopped beef meat media. 2. The growth of K. pneumonia was temporarily inhibited by nanosilver (5 ppm and 10 ppm). 3. The morphological alteration and cell damage caused by nanosilver were observed in K. pneumonia.

• Korean Chemical Engineering Research
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• v.50 no.1
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• pp.50-54
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• 2012

In this study, PANI and PANI/$TiO_2$ composites were prepared as electrode materials for a supercapacitor application. Cyclic voltammetry (CV) was performed to investigate the supercapacity properties of these electrodes in an electrolyte solution of 6 M KOH. The PANI/$TiO_2$ composites were polymerized by amount of various ratios through a simple in-situ method. The morphological properties of composites were analyzed by SEM and TEM method. The crystallinity of the composite and $TiO_2$ particle size were identified using X-ray diffraction (XRD). In the electrochemical test, The electrode containing 10 wt% $TiO_2$ content against aniline units showed the highest specific capacitance (626 $Fg^{-1}$) and delivered a capacitance of 286 $Fg^{-1}$ reversibly at a 100 $mVs^{-1}$ rate. According to the surface morphology, the increased capacitance was related to the fact that nano-sized $TiO_2$ particles (~6.5 nm) were uniformly connected for easy charge transfer and an enhanced surface area for capacitance reaction of $TiO_2$ itself.

• Polymer(Korea)
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• v.35 no.2
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• pp.161-165
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• 2011

This study is related to the preparation of biocompatible gold nanoparticles (AuNPs) which are stable in aqueous solutions for a long time. Ultrasmall polyethyleneimine (PEI)-capped AuNPs (PEI-AuNPs) with limited agglomeration were prepared in aqueous solutions at room temperature, which were based on the roles of PEI as a reductant and a stabilizer. PEI-AuNPs with an average size of 8~12 nm formed highly stable nanocolloids with an average hydrodynamic cluster size of around 50 nm in aqueous media. At a low concentration of metal precursor hydrogen tetrachloroaurate (III), the particle size was reduced noticeably. The typical peaks of gold were observed in the X-ray diffraction pattern of AuNPs. The cell viability of 98% was obtained in the case of PEI-AuNPs, while PEI was cytotoxic. The PEI-AuNP is considered to be a potential candidate as a contrast agent for computed tomography.

• Journal of the Korean Chemical Society
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• v.54 no.2
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• pp.192-197
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• 2010

The spinel compound was obtained by the thermal decomposition of Zn-Co and Zn-Ni gel prepared by sol-gel method using oxalic acid as a chelating agent. The formation of spinel compound has been comfirmed by thermogravimetric analysis (TGA), x-ray powder diffraction (XRD) and infrared spectroscopy (IR). The particle size of 13 nm~16 nm was calculated by Scherrer's equation. The sol-gel method provides a practicable and effective route for the synthesis of the spinel compound at low temperature ($350^{\circ}C$). The kinetic parameters such as activation energy (Ea) and pre-exponential factor (A) for each compound were found by means of the Kissinger method and Arrhenius equation. The decomposition of spinel compound has an activation energy about 155 kJ/mol. Finally, the thermodynamic parameters (${\Delta}G^{\varphi}$, ${\Delta}H^{\varphi}$, ${\Delta}S^{\varphi}$) for decomposition of spinel compound was determined.

• Membrane Journal
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• v.26 no.5
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• pp.381-390
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• 2016

In this study, the natural mordenite (MOR) zeolite seeds were used for the synthesis of high purity mordenite crystals. The effect of seed concentration and crystallization time on the phase purity and surface morphology of MOR crystals has also been reported. The diffraction, elemental and scanning analysis of MOR zeolite particles obtained from 100 g hydrothermal solution batch containing 3 g natural seed, hydrothermally treated at $140^{\circ}C$ for 72 h reveal the high phase-purity of as-synthesized sample having crystals of uniform size ($1-2{\mu}m$). Moreover, high seed concentration leads to the production of mesoporous MOR particles composed of needle shape primary nano crystallites. The gases adsorption performances of as-synthesized MOR particle were carried out at $25^{\circ}C$ and 0-1 bar. Surprisingly, MOR particles show good adsorption potential for $CO_2$ (97.19 mg/g) compared to other gases. Thus it confirms that high purity MOR particles can be synthesized without using any organic template which gives an advantage of separation performance at lower price.

• Journal of the Mineralogical Society of Korea
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• v.20 no.2 s.52
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• pp.135-145
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• 2007

The needs for the ultra fine particles have been increased in preparation field of raw powders such as fine ceramics and high functional products. In this study, a series of wet grinding experiments were carried out on inorganic powders such as calcite, pyrophyllite and talc by a stirred ball mill. The particle size distribution of ground products of each test material fur a given grinding time was found to be expressed by the grinding rate (selection function) which was obtained from the grinding kinetics analysis. The median diameter decreased from 6.49 to $0.47{\mu}m$ in calcite, and decreased from 3.91 to $1.14{\mu}m$ in pyrophyllite. However, in talc, median diameter was decreased a little bit from 10.30 to $6.67{\mu}m$. The grinding rate changing on calcite and pyriphyllite were similar at the same conditions. However, in the case of talc, it was observed that the grinding rate was not increased compared to other samples.

• Journal of Sericultural and Entomological Science
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• v.49 no.1
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• pp.24-27
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• 2007

Silkworm fed on the mulberry leaf mixed with silver nanoparticle to produce silver-nanoparticle embedded cocoon. Comparative analysis of silver content of cocoon shell, percentage of pupation and percentage of cocoon-shell weight showed that the optimum concentration and the feeding period of mulberry leaf mixed with silver nanoparticle were 500 ppm and the period from 3 day 5 instar to mounting of silkworm. The silver content of cocoon was observed variously by silkworm breedings. C212 variety makes pale yellow cocoon with the highest silver content(69%). Using the scanning electron microscope, we showed that the size of silver nanoparticles in silk was observed from 26.98 to 99.81nm. Silver-nanoparticle embedded silk is expected to use as high valuable application owing to the different functional properties including antibiotic characteristics and mechanical and electronic properties. The applicable fields expected is antistatic and/or electronic products with biological degradable natural materials.