• Journal of the Korean Crystal Growth and Crystal Technology
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• v.20 no.6
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• pp.272-277
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• 2010

The glass-ceramics containing bottom ash (B/A) which was a by-produced from an electrical power plant was fabricated and its crystalline phase, microstructure and mechanical properties were analyzed. At first, the glass was fabricated by adding modifier oxide $Li_2O$ to lower the melting temperature of coal bottom ash. The glass obtained was heat-treated by using a 2-stage process to crystallize, that is to say, to increase the degree of crystallization in the glass-ceramics, the first heat treatment for nucleation was performed followed by the secondary one for the growth of nucleates. The main crystalline phase formed in the glass-ceramics was ${\beta}$-spodumene and the secondary phase was $L_2SiO_3$. It was recognized that the degree of crystallization of glass-ceramics was increased with a holding time of the secondary heat treatment stage. In the case of the specimens hold up to 3 hour, the crystallization was not completed and the microstructures and morphologies of crystalline phase were not uniform. In the specimens of holding time over 9 hours, the cracks were generated inside of it, so its compressive strength would decrease due them. In conclusion, it was able to obtain the optimum condition to fabriate the glass-ceramics having the properties of high crystallization degree, uniform microstructures and morphologies and the high mechanical strength.

• Journal of the Korean Electrochemical Society
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• v.2 no.3
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• pp.150-155
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• 1999

The Electrochemical stabilities of the Brewer-Engel type intermetallic compounds of Co-Mo $(35 wt\%)$ and Ni-Mo$(35 wt\%)$ manufactured by the arc-melting method for the hydrogen electrode of $H_2-O_2$ alkaline fuel cell were investigated. Effects of temperature and concentration on the electrochemical behavior of the electrodes in the $80^{\circ}C$ 6 N KOH solution deaerated with $N_2$ gas were studied by electrochemical methods. The effect of overpotential on the electrochemical stabilities of Co-Mo and Ni-Mo intermetallic compounds was also discussed under the normal operation condition of AFC. It was shown that Co-Mo electrode had lower electrochemical stability as compared to Ni-Mo. In the case of Co-Mo electrode, a simultaneous dissolution of cobalt and molybdenum has occurred at low anodic overpotential form equilibrium hydrogen electrode potential, but the dissolution of cobalt was serious, and Co(OH)l layer on the electrode surface formed at the high anodic overpotential. In contrast the Ni-Mo electrode had high electrochemical stability because formation of the dense and thin protective $Ni(OH)_2$ layer prevented the dissolution of molybdenum.

• Korean Journal of Food Science and Technology
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• v.25 no.6
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• pp.716-723
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• 1993

To utilize effectively fish skin wasted from fish processing, a yellowfin sole skin gelatin was prepared by alkaline extraction method and the physico-chemical properties were examined. Conditions for the suitable extraction and decolorization for gelatin preparation from yellowfin sole skin are as follows: the skin is limed with 1.5% calcium hydroxide solution at $5^{\circ}C$ for 5 days, washed throughly with tap water, extracted with 6 volumes of water ($pH5.0{\sim}7.0$) to dehydrated skin for 3 hours at $50^{\circ}C$, and then bleached with 3% activated carbon. Though yellowfin sole skin gelatin was prepared under above condition, the physico-chemical property values such the melting point and gelling point of that were lower than those of pork skin gelatin. Therefore, the purified yellowfin sole skin gelatin requires a suitable modification operation for more a good quality gelatin manufacture.

• The Journal of the Petrological Society of Korea
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• v.4 no.2
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• pp.153-167
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• 1995

Emplacement ages for the granite plutons of the Jurassic and the Cretaceous times in the central Ogcheom Fold Belt were determined by Rb-Sr whole rock and mineral isocheon methods. In addition mineral ages for the plutons were determined by K-Ar and fission track methods. In turn, thermal histories and uplifting rates of the granitic bodies are elucidated from the isotopic ages. The Jecheon(~203 Ma) and Mungyeong(at lest~200 Ma) granites of the Jurassic and the Muamsa, Wolagsan and Daeyasan granites(~110 Ma) of the Cretaceous show high strontium initial ratios [$(^{87}Sr/^{86}Sr)_1$0.7100],suggesting that the granitic magmas have been generated by partial melting of crustal materials (S-type), or by mixing of mantle and crustal materials. Only mineral ages of the Sogrisan and Hyeongjebong granites (~90 Ma) were determined by K-Ar method, and petrogenesis of them were not defined yet. The two Jurassic granite plutons were cooled rapidly down to $300^{\circ}C$, right after the plutons were slowly cooled down since then, due to their deep emplacment. During the Middle Cretaceous period, the Jurassic Mungyeong granitic pluton was intruded and thermally affected much by the surrounding Wolagsan and Daeyasan granites. Accordingly the Rb-Sr mineral age, K-Ar hornblende and biotite ages of the Mungyeong granite appear to be reduced or reset due to the thermal effects above their blocking temperatures. All the cretaceous granites have been cooled much ore simply and rapidly down than the Jurassic ones below $300^{\circ}C$, owing to their shallow emplacement.

• Applied Chemistry for Engineering
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• v.10 no.4
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• pp.497-501
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• 1999

The changes of properties were studied for the polypropylene(PP)/Nylon6 blends containing different kinds of compatibilizer made by either reactive extrusion of solution reaction. The compatibilizers were PP grafted with maleic anhydride (MAH) made by reactive extrusion and solution reaction. The grafted MAH contents were 0.3 wt %, and 2.7 wt %, respectively. The composition of the PP/nylon6 blend was fixed at 75/25 by weight. Blending was carried out with twin-screw extruder (L/D=30, ${\psi}=30$) at 300 rpm. As the content of PP-g-MAH was increased, the crystallization peak of Nylon6 decreased gradually then finally disappeared. Disappearance of crystallization peak of Nylon6 was mostly affected by grafted MAH content rather than the preparation method and the amount of compatibilizer. The portion of Nylon6 that could not crystallize in its normal crystallization temperature crystallized together with PP at the crystallization temperature of PP. So called concurrent crystallization was observed. Meanwhile two more peaks were observed during heating cycle. One was exothermic peak at $193^{\circ}C$ near to crystallization temperature of Nylon6, the other was endothermic peak at $215^{\circ}C$ that was $5^{\circ}C$ lower than normal endothermic peak of Nylon6. To analyze the peaks, nylon6 was annealed in the differential scanning calorimeter. As a result, the peak at $193^{\circ}C$ was crystallization peak of imperfect crystalline of Nylon6 and the other peak at $215^{\circ}C$ was melting peak of imperfect crystalline of nylon6.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.211-211
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• 1999

Titanium nitride (TiN) thin films have useful properties including high hardness, good electrical conductivity, high melting point, and chemical inertness. The applications have included wear-resistant hard coatings on machine tools and bearings, decorative coating making use of the golden color, thermal control coatings for widows, and erosion resistant coatings for spacecraft plasma probes. For all these applications as feature sizes shrink and aspect ratios grow, the issue of good step coverage becomes increasingly important. It is therefore essential to manufacture conformal coatings of TiN. The growth of TiN thin films by chemical vapor deposition (CVD) is of great interest for achieving conformal deposition. The most widely used precursor for TiN is TiCl4 and NH3. However, chlorine impurity in the as-grown films and relatively high deposition temperature (>$600^{\circ}C$) are considered major drawbacks from actual device fabrication. To overcome these problems, recently, MOCVD processes including plasma assisted have been suggested. In this study, therefore, we have doposited Ti(C, N) thin films on Si(100) and D2 steel substrates in the temperature range of 150-30$0^{\circ}C$ using tetrakis diethylamido titanium (TDEAT) and titanium isopropoxide (TIP) by pulsed DC plamsa enhanced metal-organic chemical vapor deposition (PEMOCVD) method. Polycrystalline Ti(C, N) thin films were successfully grown on either D2 steel or Si(100) surfaces at temperature as low as 15$0^{\circ}C$. Compositions of the as-grown films were determined with XPS and RBS. From XPS analysis, thin films of Ti(C, N) with low oxygen concentration were obtained. RBS data were also confirmed the changes of stoichiometry and microhardness of our films. Radical formation and ionization behaviors in plasma are analyzed by optical emission spectroscopy (OES) at various pulsed bias and gases conditions. H2 and He+H2 gases are used as carrier gases to compare plasma parameter and the effect of N2 and NH3 gases as reactive gas is also evaluated in reduction of C content of the films. In this study, we fond that He and H2 mixture gas is very effective in enhancing ionization of radicals, especially N resulting is high hardness. The higher hardness of film is obtained to be ca. 1700 HK 0.01 but it depends on gas species and bias voltage. The proper process is evident for H and N2 gas atmosphere and bias voltage of 600V. However, NH3 gas highly reduces formation of CN radical, thereby decreasing C content of Ti(C, N) thin films in a great deal. Compared to PVD TiN films, the Ti(C, N) film grown by PEMOCVD has very good conformability; the step coverage exceeds 85% with an aspect ratio of more than 3.

• Journal of the Microelectronics and Packaging Society
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• v.17 no.3
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• pp.51-57
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• 2010

Thermoelectric properties of the p-type $(Bi,Sb)_2Te_3$, hot-pressed with the $(Bi,Sb)_2Te_3$ powders fabricated by melting/grinding method, were characterized with variation of the hot-pressing conditions. Thermoelectric characteristics of the hot-pressed $(Bi,Sb)_2Te_3$ were also analyzed with addition of $ZrO_2$ as nano inclusions. With increasing the hotpressing temperature from $350^{\circ}C$ to $550^{\circ}C$, Seebeck coefficient and electrical resistivity decreased from 275 ${\mu}V$/K to 230 ${\mu}V$/K and 6.68 $m{\Omega}$-cm to 1.86 $m{\Omega}$-cm, respectively. The power factor decreased with addition of $ZrO_2$ nano powders more than 1 vol%, implying that the optimum amount of $ZrO_2$ nano inclusions to get a maximum power factor would be less than 1 vol%.

• Polymer(Korea)
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• v.27 no.5
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• pp.458-463
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• 2003

The effect of ozone surface treatment of montmorillonite (MMT) was investigated in thermal stabilities of polypropylene (PP) nanocomposites. Sodium montmorillonite (Na$\^$+/-MMT) was organically modified with dodecylammonium chloride. The surface properties of MMT, including the specific surface area (S$\_$BET/), equilibrium spreading pressure ($\pi$$\_$e/), and London dispersive component (${\gamma}$s$\^$L/), were studied by the BET method with $N_2$ adsorption. Also, the thermal stabilities of the nanocomposites were investigated in DSC and TGA. As experimental results, $\pi$$\_$e/ and ${\gamma}$s$\^$L/ of the ozonized dodecylammonium chloride (DA-MK ( $O_3$)) were increased in about 1.7 and 3.5 mJ/ $m^2$, resulting from the increasing of the micropores. From the DSC results, it was found that the melting temperature and crystallization temperature of PP/DA-MK and PP/DA-MK ( $O_3$) were higher that those of pure PP. These results were explained that dodecylammonium chloride of nano-scale led to a nucleation effect for PP crystallization. Also, it was found that E$\_$t/ of the PP/DA-MK ( $O_3$) nanocomposies was increased within about 64 kJ/mol. These results were probably explained by the improvement of dispersivity of DA-MK ( $O_3$) in a PP matrix.

• Journal of the Mineralogical Society of Korea
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• v.13 no.3
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• pp.164-170
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• 2000

Neutron single crystal and powder diffraction techniques have been applied to the structure analysis of yttria-stabilized zirconium, Z $r_{0.73}$ $Y_{0.27}$ $O_{1.87}$., prepared by the skull-melting method. The crystal structure has been determined to be cubic symmetry, space group Fm/equation omitted/ with a=5.155(2)$\AA$, V=136.99(5)$\AA$, Z=4, and R(F)=5.65%, $\omega$R(I)=10.57% for 70 integrated intensities of Bragg Peaks observed from single crystal of Z $r_{0.73}$ $Y_{0.27}$ $O_{1.87}$. The stabilizer atoms randomly occupy the zirconium sites and there are displacements of oxygen atoms with amplitudes of $\Delta$/a~0.033 and 0.11 along <110> and <100> directions from the ideal positions of the fluorite structure, respectively. There are no significant differences in crystallographic data between the single crystal and powder studies. Diffraction pattern after Rietveld refinement, using neutron powder data, has shown the evidence of a tetragonal impurity phase, or a slight tetragonal distortion.

• Korean Journal of Microbiology
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• v.43 no.2
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• pp.91-99
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• 2007

For the detection of Human Immunodeficiency Virus (HIV), multiple and ultra-rapid real-time PCR methods were developed. The target DNA sequences were deduced from HIV-1 specific 495bp partial env gene (gi_1184090) and from HIV-2 specific 294 bp partial env gene (gi_1332355), and were synthesized by using PCR-based gene synthesis on the reason of safety. Ultra-rapid real-time PCR was performed by $Genspector^{TM}$ using microchip-based, $1\;{\mu}l$ of reaction volume with extremely short time in each 3 step in PCR. The detection including DNA-amplification and melting temperature analysis was completed inner 15 minutes. The HIV-1 specific 117 bp-long and HIV-2 specific 119 bp-long PCR products were successfully amplified from minimum of template,2.3 molecules of each env gene. This kind of real-time PCR was designated as ultra-rapid real-time PCR in this study and it could be applied not only an alternative detection method against HIV, but also other pathogens using PCR-based detection.