• Korean Journal of Microbiology
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• v.43 no.4
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• pp.264-272
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• 2007

For the detection of human immunodeficiency virus (HIV), ultra-rapid real-time PCR methods were developed. The target DNA sequences were used 495 bp HIV-1-specific env gene (gi_1184090) and 294 bp HIV-2-specific env gene (gi_1332355). Ultra-rapid real-time PCR was peformed by $Genspector^{TM}$ (Samsung, Korea) using microchip-based, $6\;{\mu}l$ of reaction volume with extremely short running time in only 2 steps (denaturation, annealing/extension) in each cycle of PCR. Total reaction for 30 cycled ultra-rapid PCR detection including melting temperature analysis was completed in 7 min and 30 sec. The HIV-1-specific 117 bp-long or HIV-2-spe-cific 119 bp-long PCR products were successfully amplified from the minimum of template, $2.3{\times}10^3$ copies of each euv gene using 30 cycled two-steps ultra-rapid PCR. This kind of ultra-rapid real-time PCR method would be useful not only for the rapid-detection of HIV, but also rapid-detection of other pathogens.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.4
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• pp.431-443
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• 2007

Statement of problem: Injuries along with discomfort may result on the oral mucosa when non-rigid material is used as the major connector in construction of RPD, since nonrigid major connectors transmit unstable forces throughout the appliance. Titanium which recently draws attention as a substitute of Co-Cr had a difficulty in fabricating due to high melting temperature but the development of casting technique makes it possible to apply to the clinical case. Purpose: The purpose of this study was to investigate the rigidity and the castability of titanium upper major connector by design and make a comparison with Co-Cr major connectors which are widely used in clinical cases now. Material and methods: Casting was done using CP-Ti(Grage 2) (Kobe still Co., Japan) for the experimental groups, and 4 various designs namely palatal strap, U-shaped bar, A-P strap, and complete palatal plate were casted and 5 of each designs were included in each group. For the experimental group, Universal testing machine (Model 4502; Instron, Canton, Mass) was used to apply vertical torsional force vertically to the horizontal plane of major connector. In the second experiment, Vertical compressive force was applied to the horizontal plane of major connector. As a comparative group, Co-Cr major connector was equally manufactured and underwent the same experimental procedures Strain rate was measured after constant loading for one minute duration, and statistical analysis was done with SPSS ver.10.0 for WIN(SPSS. Inc. USA). From the one-way ANOVA and variance analysis (P=0.05), Scheffe's multiple comparison test implemented. Results: 1. Least amount of strain was observed with complete palatal plate followed by A-P bar, palatal bar, and the U-shaped bar having most amount of strain. 2. In all designs of titanium major connector, less strain rate was observed under compressive loading than under torsional loading showing more resistance to lateral force. 3. For titanium major connector, less strain rate was observed when the force is applied to the first premolar area rather than to the second molar area indicating more strength with shorter length of lever. 4. In Comparison of Co-Cr major connector with titanium major connector, palatal strap and U-shaped bar designs showed higher strength under torsional force that is statically significant, and under compressive force, no significant difference was observed expert for U-shaped bar. 5. In titanium major connector, complete palatal plate showed lowest success rate in casting when compared with the Co-Cr major connector. Conclusion: Above results prove that when using titanium for major connector, only with designs capable of generating rigidity can the major connector have almost equal amount of rigidity as Co-Cr major connector and show lower success rate in casting when compared with the Co-Cr major connector.

• 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.637-642
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• 1993

Changes in the physicochemical characteristics and triglyceride molecular species of corn oil under the following condition of hydrogenation; temperature $180^{\circ}C,\;H_{2}$, pressure $2.0{\pm}0.3bar$, the amount of Ni catalyst 0.048%(Ni/oil by wt.) and agitation speed 300 rpm. The rate of hydrogenation, expressed as the reduction rate of the iodine value with respect to time, is first order and high (K>0.01). When the reduction rate of the iodine value was 39.9%, hydrogenation time was 30 min, 18:1 was highest(77.06%), thereafter that was decreased and 18:0 increased. In the triglyceride composition, OLL, LLL were reduced markedly in 10 min, thereafter reduced slightly. And PLO, PLL, OLO were eliminated in first 30 min. On the other hand, POO, PLS(CN52) and OOO, SLO(CN54) were increased sharply, and then that showed little change. The melting point(MP) of hydrogenated corn oil were $27.8^{\circ}C\;and\;44.1^{\circ}C$ after 20 min and 60 min, respectively. Trans isomer content increased to 46.8% during 40 mins of hydrogenation and then decreased insignificantly. The solid fat content were linearly increased with hydrogenation time. Accordingly, it is confirmed that this condition of hydrogenation was selective, preferential elimination of polyunsaturated fatty acid went stepwise and trans isomer was formed promotedly. These results suggest that fat modification techniques can be used for practical application.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.5
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• pp.547-553
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• 2016

Black carbon (BC) contained in particulate matter (PM) originating from the exhaust gases of ships' diesel engines has been receiving great attention as a cause of glacial melting and warming in the polar regions. In this study, we took samples from various locations of PM emitted from the training ship (T/S) HANBADA's main engine, in cooperation with the Korea Maritime and Ocean University. We analyzed the structure and characteristics of these samples using high-resolution transmission electron microscopy (HR-TEM) and applied our findings as fundamental research for developing PM reduction technology. We also employed our results to determine appropriate preemptive action to meet upcoming PM/BC regulations. In addition, we confirmed the emission trend of pollutants from exhaust gases under various engine operating conditions using an exhaust gas analyzer. Results obtained from the analysis of HR-TEM images showed that the structure of the PM is chain-like wispy agglomerates consisting of a number of individual spherical particles. As the sampling location was moved away from the turbo charger (T/C) towards the funnel, more condensates were observed at a low temperature and the molecular structure of the PM lost its characteristic BC structure as an amorphous structure gradually appeared. Furthermore, through the analysis of exhaust gases, we predicted a decrease in PM concentration in the exhaust stream as engine rpm increase.

• 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.

• Journal of the Microelectronics and Packaging Society
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• v.15 no.4
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• pp.51-57
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• 2008

In this paper, wetting and interfacial reaction properties for low Ag containing Sn-Ag-Cu Pb-free solder alloy, i.e., Sn-0.3Ag-0.7Cu were investigated and compared with those of Sn-1.0Ag-0.5Cu and Sn-3.0Ag-0.5Cu. Melting behavior and stress-strain curves of some Sn-xAg-xCu alloys were also measured using a differential scanning calorimeter(DSC) and a tensile test machine, respectively. In order to enhance insufficient wetting properties of Sn-0.3Ag-0.7Cu alloy, the improvement of wetting properties were analyzed by applying fluxes containing higher content of halide or indium adding of 0.2wt.% into the solder alloy. It was concluded that the small addition of indium is more effective for the improvement of wettability in low temperature range of $230{\sim}240^{\circ}C$ than applying flux containing higher content of halide.

• 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%.

• Journal of the Korean Ceramic Society
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• v.39 no.8
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• pp.721-727
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• 2002

In order to overcome trade-off among compositions, process and properties of the glasses with high PbO-base composition for PDP Rib, we studied glass crystallization and crystallization kinetics by Differential Thermal Analysis(DTA). Glass powder was obtained through melting/cooling/grinding, with 3 wt%TiO2 addition for the crystal nucleation and growth in $62PbO-19B_2O_3-10SiO_2-9(Al_2O_3-K_2O-BaO-ZnO)$(in wt%) composition glass. This powder was heat-treated for 1 to 10 h at $445^{\circ}C$ for nucleation. DTA measurements were performed to obtain the crystallization peak with $5∼25^{\circ}C/min$ heating rates. DTA crystallization peak temperature increased with increasing the heating rate and decreased with increasing the heating time. Because the Avrami parameter (n) was approximately 1, the surface crystallization occurred. The maximum nucleation time was 2 h.