• Transactions on Electrical and Electronic Materials
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• v.13 no.5
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• pp.241-244
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• 2012

Antimony doped tin oxide (ATO) thin films on glass substrate were prepared by the chemical solution deposition (CSD) method, using sol-gel solution synthesized by non-alkoxide precursors and the sol-gel route. The crystallinity and electrical properties of ATO thin films were investigated as a function of the annealing condition (both annealing environments and temperatures), and antimony (Sb) doping concentration. Electrical resistivity, carrier concentration, Hall mobility and optical transmittance of ATO thin films were improved by Sb doping up to 5~8 mol% and annealing in a low vacuum atmosphere, compared to the undoped tin oxide counterpart. 5 mol% Sb doped ATO film annealed at $550^{\circ}C$ in a low vacuum atmosphere showed the highest electrical properties, with electrical resistivity of about $8{\sim}10{\times}10^{-3}{\Omega}{\cdot}cm$, and optical transmittance of ~85% in the visible range. Our research demonstrates the feasibility of low-cost solution-processed transparent conductive oxide thin films, by controlling the appropriate doping concentration and annealing conditions.

• ETRI Journal
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• v.25 no.2
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• pp.73-80
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• 2003

This paper describes an effective method for forming silicon oxide on silica-on-silicon platforms, which results in excellent characteristics for hybrid integration. Among the many processes involved in fabricating silica-on-silicon platforms with planar lightwave circuits (PLCs), the process for forming silicon oxide on an etched silicon substrate is very important for obtaining transparent silica film because it determines the compatibility at the interface between the silicon and the silica film. To investigate the effects of the formation process of the silicon oxide on the characteristics of the silica PLC platform, we compared two silicon oxide formation processes: thermal oxidation and plasma-enhanced chemical vapor deposition (PECVD). Thermal oxidation in fabricating silica platforms generates defects and a cristobalite crystal phase, which results in deterioration of the optical waveguide characteristics. On the other hand, a silica platform with the silicon oxide layer deposited by PECVD has a transparent planar optical waveguide because the crystal growth of the silica has been suppressed. We confirm that the PECVD method is an effective process for silicon oxide formation for a silica platform with excellent characteristics.

• Journal of the Korean Vacuum Society
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• v.6 no.S1
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• pp.1-15
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• 1997

Titanium oxide films were prepared by ion beam enhanced deposition where the films were synthesized by deposition titianium atoms and simultaneously bombarding with xenon ion beam at an energy of 40 keV in an $O_2$ environ,ent. Structure and composition of titanium oxide films were investigated by X-ray Doffractopm (XRD) Ritjerfprd Backscattering Spectroscopy (RBS) and X-ray Diffraction(XRD) Rutherford Backscattering Spectroscopy (RBS) and X-ray photoelectron spectroscopy (XPS) The results show that thestructure of the prepared films exhibit a rutile phase structure wit high(200) orientation and the O/Ti ratio of the titanium oxide films was about 2:1 XPS anlysis shows that $Ti^{2+},Ti^{3+}\;and\;Ti^{4+}$ chemical states exist on the titanium oxide films. the blood compatibility of the titanium oxide films was studied by measurements of blood clotting time and platelet adhesion. The results show that the anticoagulation property of titanium oxide films improved significantly and better than that of LTI-carbon which was widely used to fabricate artificial heart valve.

• Archives of Pharmacal Research
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• v.27 no.12
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• pp.1233-1237
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• 2004

The effects of four tanshinones isolated from Tanshen (the root of Salvia miltiorrhiza Bunge, Labiatae) were tested for their inhibition of nitric oxide production in macrophage cells, and the underlying molecular mechanisms studied. Of the four tanshinones used, 15, 16-dihydrotanshinone- I, tanshinone-IIA and cryptotanshinone, but not tanshinone I, demonstrated significant inhibition of the LPS-induced nitric oxide production in RAW 264.7 cells, with calculated $IC_{50}$ values of 5, 8, and 1.5 ${\mu}M$ , respectively. Tanshinones exerted inhibitory activities on the LPS-induced nitric oxide production only when applied concurrently with LPS, and tanshinone- IIA and cryptotanshinone were found to inhibit LPS-induced NF-$_KB$ mobilization and extracellular- regulated kinase (ERK) activation, respectively. These results suggest that tanshinones inhibit LPS-induced nitric oxide generation by interfering with the initial stage of LPS-induced expression of certain genes. NF-$_KB$ and ERK could be the molecular targets for tanshinones for the inhibition of LPS-induced nitric oxide production in macrophage cells.

• Journal of the Korean institute of surface engineering
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• v.30 no.3
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• pp.191-201
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• 1997

Non-passivated electrolytic tinplates withour conventinal chemical treatment self-oxidize in ambient atmosphere to from yellow stain on the outermost surface during the long-term storage. The degree of yellowness of the stain increased linerly with the oxide thickness due to the interfeefence color of the $SnO_2$ Even though the thickness of the oxide layer was very thin, less than 100$\AA$ , it exerts an undesirable influence on the can-making processes, particularly the stripping behavior after ironing. Investigations were carried out on the morphologies of the coating layer, the changes in oxide thickness during successive can-making processes and the averge friction coefficients with the different oxide thinkness. These oxide layers were broken up and distributed within the bulk tin coating during the ironing process. This redistribution of the oxide layer prvented smooth pressing-aside of the tin coating layer, resulting in an increase in the ironing friction coefficient. As the friction was increased, the residual stress along the can wall thinkness(i.e., the hoop stress) was also increased. Due to both the oxibe layer accumulation, which increased the friction coefficient, and the hoop stress, can stripping efficiency without roll-back is reduced.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.37-40
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• 1999

For the first time, charge trapping nonvolatile semiconductor memories with the deoxidized oxynitride gate dielectric is proposed and demonstrated. Gate dielectric wit thickness of less than 1 nm have been grown by postnitridation of pregrown thermal silicon oxides in NO ambient and then reoxidation. The nitrogen distribution and chemical state due to NO anneal/reoxidation were investigated by M-SIMS, TOF-SIMS, AES depth profiles. When the NO anneal oxynitride film was reoxidized on the nitride film, the nitrogen at initial oxide interface not only moved toward initial oxide interface, but also diffused through the newly formed tunnel oxide by exchange for oxygen. The results of reoxidized oxynitride(ONO) film analysis exhibits that it is made up of SiO$_2$(blocking oxide)/N-rich SiON interface/Si-rich SiON(nitrogen diffused tunnel oxide)/Si substrate. In addition, the SiON and the S1$_2$NO Phase is distributed mainly near the tunnel oxide, and SiN phase is distributed mainly at tunnel oxide/Si substrate interface.

• Carbon letters
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• v.27
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• pp.81-89
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• 2018

The present study aimed to prepare a novel efficient flame retardant additive for polypropylene. The new flame retardant was prepared by chemical grafting of melamine to graphene oxide with the aid of thionyl chloride. Fourier-transform infrared spectroscopy and thermogravimetric analysis proved that melamine had been successfully grafted to the graphene oxide. The modified graphene oxide was incorporated into polypropylene via solution mixing followed by anti-solvent precipitatio. Homogeneous distribution as well as exfoliation of the nanoplatelets in the polymer matrix was observed using transmission electron microscopy. Thermogravimetric analysis showed a significant improvement in the thermo-oxidative stability of the polymer after incorporating 2 wt% of the modified graphene oxide. The modified graphene oxide also enhanced the limiting oxygen index of the polymer. However, the amount of improvement was not enough for the polymer to be ranked as a self-extinguishing material. Cone calorimetry showed that incorporating 2 wt% of the modified graphene oxide lowered total heat release and the average production rate of carbon monoxide during burning of the polymer by as much as 40 and 35%, respectively. Hence, it was concluded that the new flame retardant can retard burning of the polymer efficiently and profoundly reduce suffocation risk of exposure to burning polymer byproducts.

• Journal of the Korean institute of surface engineering
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• v.54 no.2
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• pp.77-83
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• 2021

In this study, we investigated various coating methods of graphene oxide on the surface of a petri dish made of polystyrene and analyzed the physical and chemical properties of the coated surface. For coating, spinning, spraying and pressing methods were attempted. The coated surface was characterized by SEM, Raman Spectroscopy, AFM, FT-IR, UV-Vis Spectroscopy and Contact Angle measurement. By spin coating and spray coating, well distributed graphene oxide in the form of multiple islands on the plastic surface with an average size of 5 to 20㎛ are observed by SEM, and high binding energy between graphene oxide and plastic surface is measured by AFM. In case of hand press coating, graphene oxide of 10㎛ or more was observed, and low surface energy was measured. By FT-IR and Raman Spectroscopy analysis, surface coating of graphene oxide was confirmed.

• Korean Chemical Engineering Research
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• v.43 no.6
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• pp.740-744
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• 2005

Perovskite-type oxide $La_{1-x}Sr_xCo_{1-y}Fe_yO_{3-{\delta}}$ sols were prepared by sol-gel method using $La(NO_3)_3{\cdot}xH_2O$, $Sr(NO_3)_2$, $Co(NO_3)_2{\cdot}6H_2O$ and $Fe(NO_3)_3{\cdot}9H_2O$ as starting materials. The properties of the perovskite-type oxide sols were investigated by viscometer, FT-IR, TG-DTA and XRD. The prepared sols showed 1.16 cp in average viscosity, and a strong acidic condition of pH 0.5, irrespective of composition of the starting materials. The viscosity of sols at the same volume decreases, but the gelation time of sols, at which the sol viscosity increases rapidly, increases when increasing La concentration in composition of starting materials.

• Korean Chemical Engineering Research
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• v.49 no.1
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• pp.1-9
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• 2011

Platinum catalysts were prepared by impregnating platinum precursor on titania-, vanadia-, zirconia- and ceria-incorporated silicas followed by hydrogen peroxide treatment. The effects of the oxide incorporation and the hydrogen peroxide treatment in the preparation of the platinum catalysts on their platinum dispersion and catalytic activity in carbon monoxide oxidation were investigated. XRD, TEM, EXAFS, XPS and carbon monoxide chemisorption studies confirmed the high dispersion of platinum even on silica by the oxide incorporation and hydrogen peroxide treatment. However, the type of oxides incorporated on silica caused considerable variances in the adsorption and the catalytic activity in the oxidation of carbon monoxide on them. The incorporation of titania, zirconia and ceria on silica and further hydrogen peroxide treatment enhanced the platinum dispersion, resulting in the improved catalytic activities. Among the catalysts supported on the oxide-incorporated silicas, the platinum catalyst supported on zirconia-incorporated silica exhibited the highest activity because of the highest platinum dispersion due to the formation of Pt-O-Zr bonds.