• Proceedings of the Korean Vacuum Society Conference
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• 1995.02a
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• pp.28-28
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• 1995

• Proceedings of the Materials Research Society of Korea Conference
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• 1998.08a
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• pp.110.4-110
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• 1998

• Journal of Electrochemical Science and Technology
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• v.3 no.4
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• pp.185-189
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• 2012

A.c. impedances of mechanically polished CP-Ti specimens were measured at open-circuit potential (OCP) with immersion time and under applied anodic potentials between -0.2 and 1 $V_{Ag/AgCl}$ in 0.1 M NaOH solution. Capacitances of native oxide films ($C_{ox,na}$) grown naturally and capacitances of anodic oxide films ($C_{ox,an}$) formed under applied anodic potentials were obtained to examine the growth of native and anodic oxide films in 0.1 M NaOH solution and how to use $C_{ox,na}$ for the surface area measurement of Ti specimen. $1/C_{ox,na}$ and $1/C_{ox,an}$ appeared to be linearly proportional to OCP and applied potential ($E_{app}$), with proportional constants of 0.086 and 0.051 $uF^{-1}\;V^{-1}$, respectively. The $C_{ox,na}$ also appeared to be linearly proportional to geometric surface area of the mechanically polished CP-Ti fixture specimen, with proportional constants of 11.3 and $8.5{\mu}F\;cm^{-2}$ at -0.45 $V_{Ag/AgCl}$ and -0.25 $V_{Ag/AgCl}$ of OCPs, respectively, in 0.1 M NaOH solution. This linear relationship between $C_{ox,na}$ and surface area is suggested to be applicable for the measurement of real surface area of Ti specimen.

• Korean Journal of Medicinal Crop Science
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• v.21 no.3
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• pp.191-196
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• 2013

The effect on the antioxidant activity and Nitric Oxide activity production inhibitory activity of Taraxacum has not been known. Therefore, phenolics and flavonoid contents were investigated from the ethanol extracts of five different Taraxacum species. The results showed that, among the five Taraxacum, T. hallaisanensis contains the highest total phenolic and flavonoid contents. When the antioxidant activity was measured by DPPH, $ABTS^+$ and reducing power activity, the free radical scavenging activity of T. hallaisanensis was also the highest among five Taraxacum species. However, measurement by CCK-8 assay in Raw264.7 cells indicated that the extracts of Taraxacum species have no effect on cell viability. Moreover, we also investigated the effect of Taraxacum species on NO scavenging activity in lipopolysaccharide (LPS)-stimulated Raw264.7 cells. The results clearly showed that Taraxacum species inhibited NO production, and the inhibitory effect of T. hallaisanensis was the strongest. The above results suggested that Taraxacum species affected the antioxidant and NO scavenging activity, and among the five species, antioxidant and NO scavenging activity assay of T. hallaisanensis was significantly higher than those of other four Taraxacum species. Therefore, T. hallaisanensis could be used as a potential drug with anti-oxidant and anti-inflammatory effect.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.3_1spc
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• pp.544-550
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• 2013

A grooved surface with anisotropic wettability was fabricated on a silicon substrate using photolithography, reactive ion etching, and a KOH etching process. The contact angles (CAs) of water droplets were measured and compared with the theoretical values in the Cassie state and Wenzel state. The experimental results showed that the contact area between a water droplet and a solid surface was important to determine the wettability of the water. The specimens with native oxide layers presented CAs ranging from $71.6^{\circ}$ to $86.4^{\circ}$. The droplets on the specimens with a native oxide layer could be in the Cassie state because they had relatively smooth surfaces. However, the CAs of the specimens with thick oxide layers ranged from $33.4^{\circ}$ to $59.1^{\circ}$. This indicated that the surface roughness for a specimen with a relatively thick oxide layer was higher, and the water droplet was in the Wenzel state. From the CA measurement results, it was observed that the wetting on the grooved surface was anisotropic for all of the specimens.

• Journal of the Korean institute of surface engineering
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• v.50 no.3
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• pp.147-154
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• 2017

This research was conducted to investigate the electrochemical properties of the thin air-formed oxide film-covered AZ31 Mg alloy. Native air-formed oxide films on AZ31 Mg alloy samples were prepared by knife-abrading method and the changes in the electrochemical properties of the air-formed oxide film were investigated in seven different electrolytes containing the following anions $Cl^-$, $F^-$, $SO{_4}^{2-}$, $NO_3{^-}$, $CH_3COO^-$, $CO{_3}^{2-}$, and $PO{_4}^{3-}$. It was observed from open circuit potential (OCP) transients that the potential initially decreased before gradually increasing again in the solutions containing only $CO{_3}^{2-}$ or $PO{_4}^{3-}$ ions, indicating the dissolution or transformation of the native air-formed oxide film into new more protective surface films. The Nyquist plots obtained from electrochemical impedance spectroscopy (EIS) showed that there was growth of new surface films with immersion time on the air-formed oxide film-covered specimens in all the electrolyte. The least resistive surface films were formed in fluoride and sulphate baths whereas the most protective film was formed in phosphate bath. The potentiodynamic polarization curves illustrated that passive behaviour of AZ31 Mg alloy under anodic polarization appears only in $CO{_3}^{2-}$, or $PO{_4}^{3-}$ ions containing solutions and at more than $-0.4V_{Ag/AgCl}$ in $F^-$ ion containing solution.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.12
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• pp.1852-1858
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• 1990

The sheet resistance and thickness of Ti-Silicides treated RTA at 600, 700, 800\ulcorner was measured with amount of BF2 implanted in Si substrate. And the profile of BF2 was studied by SIMS. The formation of TiSi2 starts at 700\ulcorner. The Ti-Silicides almost consist of TiSi2 and have a low resistivity about 16列 cm at 800\ulcorner. The sheet resistances of Ti-silicides increase and thicknesses of it decrease with increasing dose of BF2. Considering the results of SIMS and the thickness of native oxide, the decrease of thickness of Silicides chiefly results from the increase of native oxide thickness with increasing dopants.

• Journal of the Korean Ceramic Society
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• v.28 no.11
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• pp.859-864
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• 1991

High quality lead titanate thin films were fabricated by spin coating on a silicon substrate. The resulting dried gel layers were uniform in thickness through 2$\times$2 $\textrm{cm}^2$ area, and polycrystalline perovskite structures developed almost crack free with a heat treatment above 50$0^{\circ}C$ in films with thickness above 360 nm. Metastable pyrochlore structures were observed in films with thickness of 160 nm when heat treated at 500 and $600^{\circ}C$, but these structure did not appear in films with thickness of 360 nm. The thickness dependence in crystal structure of films was studied. by varying the substrate condition and analyzing the interface between the film and substrate. In native oxide films on silicon stbstrates, amorphous dried gel layers were heterogeneously nucleated. Metastable cubic pyrochlore structure could be crystallized in amorphous native oxide.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.2
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• pp.423-428
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• 1999

Potato starches were hydroxypropylated with 2.5, 5.0, 7.5, and 10.0% propylene oxide(PO) to improve mechanical properties of starch polyethylene film. Starch polyethylene cast films were prepared that contained 5% or 10% of the hydroxypropylated potato starch. Mechanical properties of these films were measured and compared to those of the films containing native potato starch. DS(degree of substitution) increased proportionally as propylene oxide concentration increased. Relative crystallinity in X ray diffraction patterns was decreased and starch granule observed by scanning electron micro scopy was destroyed by severe hydroxypropylation. In color properties of films, b value was not significantly different in the films but 5% starch polyethylene films with 2.5 PO starch showed the lowest L and a value. Tensile strength and strain energy of the films except the film containing 10.0 PO starch were higher than those of the containing native starch.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.140.1-140.1
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• 2013

The native silicon-oxide (SiOx) layer at the metal/Silicon interface acts as an electrical resistance to the metal contact of devices. Various methods are proposed for removing this layer, such as sputtering before metal contact formation or high temperature annealing. We studied the chemical evolution of the Au/SiOx/Si system during the annealing at $500^{\circ}C$ using a spatially resolved photoelectron emission method. Scanning photoelectron emission microscopy (SPEM) and core level spectra from local area of the sample show the inhomogeneous oxidation and formation of silicide of Au, as well as valence band spectra reveals the role of Au atoms during the dissociation process of SiOx.