• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.5
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• pp.398-405
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• 2002

The degradation characteristics of MgO additive for the ZnO ceramic devices fabricated by the standard ceramic techniques are investigated in this study. These devices were made from basic Matsuoka's composition. Especially, MgO was added to analyze the degradation characteristics and devices were sintered in air at $1200^{\circ}C$. The conditions of DC degradation test were $115\pm2^{\circ}C$ for 12h. Using XRD and SEM, the phase and microstructure of samples were analyzed, respectively. The elemental analysis in the microstructures was performed by EDS, E-J analysis was used to determine $\alpha$. Frequency analysis was accomplished to understand the relationship between $R_G$ and $R_B$ with the electric stress at the equivalent circuit.

• Korean Journal of Metals and Materials
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• v.46 no.8
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• pp.489-494
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• 2008

The effect of drawing rate on the electrochemical properties of 3003 Al alloys in 5 wt.% NaCl solution was investigated by electrochemical techniques (potentiodynamic polarization test, potentiostatic polarization test, electrochemical impedance spectroscopy (EIS)) and surface analyses (OM, SEM, EDS). Four kinds of automotive pipe materials were prepared (raw material, drawing rate = 5, 10, 15%). As the drawing rate of Al alloy tube increased, the pitting corrosion resistance increased due to the enrichment of Al oxides on the surface.

• Journal of Conservation Science
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• v.28 no.4
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• pp.417-425
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• 2012

Bronze Mirror with fine linear designs in the bronze age shows the greatest alloy and casting skills of the day and presents the highest level of handcrafting and molding techniques. Lately, Lost-wax casting and sand-mould casting were used for the restoration of the national treasures of No. 141 and No. 143 Bronze Mirror with fine linear designs. Also the Principle Component Analysis, Microstructure Analysis, X-ray and SEM-EDS analysis were carried out on the restored Bronze Mirror with fine linear designs. Bronze Mirror that is made of sand-mould casting, hardly has a eutectoid and it is observed as a ${\alpha}$ dendrite. In contrast, Bronze Mirror that is made of lost-wax casting, the eutectoid has found through the ${\alpha}$ dendrite. As we compare lost-wax casting to the sand-mould casting through an analysis of restored Bronze Mirror, mostly, sand-mould casting has better castability and it seems that it brings a clear and equal Bronze Mirror as it has a low cooling rate. In this way, we are able to confirm that there is a big difference between the method by lost-wax casting and by sand-mould casting through an analysis of microstructure and restored Bronze Mirror. If such research will be continued, it will be an opportunity that investigates diverse methods of production techniques.

• Applied Chemistry for Engineering
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• v.9 no.1
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• pp.135-140
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• 1998

The constituents of deposits on paper machine and holes/spots in paper have been analyzed by a combination of analytical techniques, such as FTIR, Py-GC-MS, and EDS. FTIR spectroscopy was used prior to Py-GC-MS and EDS analysis, as a preliminary analysis. The analysis of organic components was carried out with a pyrolysis unit connected to a GC-MS, and inorganic components in ash were analyzed by SEM equipped with an EDS analyzer after pyrolysis at $590^{\circ}C$. The deposits on the dryer section were complex pitch, which was the mixture of the organic components of fatty acid ester and starch, and the inorganic components of talc, clay, and calcium carbonate. The complex pitch was estimated to come from the coated broke. We knew the deposits on the metering rod of sym-sizer were associated with the interaction of unstable alkyl keten dimer(AKD) and $CaCO_3$. The compositions of holes or spots varied considerably and were associated with chemical interaction within the system. The holes, spots, and blotches in the finished paper were PE and PP from pulp sources, complex pitch that were caused by the interaction of the different additives in the system, polymer such as flexible PVC that was used for the prop of palette, and hot melt as adhesives that came from the inadequate handling of broke. In addition, we identified that poly(caprolactam) which is used for forming fabrics or press felts, could be mixed with the raw materials by accident and results in streaks on coating.

• Journal of the Mineralogical Society of Korea
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• v.10 no.2
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• pp.139-147
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• 1997

The Janghang smelter is the first lead, zinc and copper smelting facility in Korea which was operated for a half century from 1936 to 1989. The clay minerals and their heavy metal association in the soil profile around the smelter have been studied using XRD, EPMA, SEM-EDS, TEM, EPR and sequential extraction techniques. The soils in A horizon are highly acidic showing pH 4.45. The pH is going up with increasing depth. They have residual water contents of 1.18-1.51 wt%, loss on ignition of 6.32-7.79 wt%, and carbon contents of 0.08-0.88 wt%. Soils consist of quartz, feldspar, muscovite, kaolinite, vermiculite, biotite, chlorite, goethite and hematite in the decreasing abundance. The contents of clay minerals, especially vermiculite and chlorite, decrease with increasing depth. Sequential extraction experiments for the profile samples show that heavy metals (Zn, Cu, Pb, Cd) are highly concentrated in the A horizon of the soil profile as water-extractable (mostly amorphous), MgCl2-extractable (exchangeable in clay minerals), and organic phases. The heavy metal contents decrease with increasing depth. It suggests that the heavy metals are mainly associate with clay minerlas in an exchangeable state. It is also noted that heavy metals are highly concentrated in the manganese and iron oxide phases.

• Bulletin of the Korean Chemical Society
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• v.32 no.6
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• pp.1865-1872
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• 2011

This study investigates the sensitivity of a gas sensor to volatile organic compounds (VOCs) at various operating temperatures and catalysts. Nano-sized powdered $WO_3$ prepared by sol-gel and chemical precipitation methods was mixed with various metal oxides. Next, transition metals (Pt, Ru, Pd, and In) were doped on the surface of the mixture. Metal-$WO_3$ thick films were prepared using the screen-printing method. The physical and chemical properties of the films were studied by SEM/EDS, XRD, and BET techniques. The measured sensitivity to VOCs is defined as the ratio ($R_a/R_g$) of resistance ($R_{air}$) of $WO_3$ film in the air to resistance ($R_{gas}$) of $WO_3$ film in a VOCs test gas. The sensitivity and selectivity of the films were tested with various VOCs such as acetaldehyde, formaldehyde, methyl alcohol, and BTEX. The thick $WO_3$ film containing 1 wt % of Ru and 5 wt % of $SnO_2$ showed the best sensitivity and selectivity to acetaldehyde gas at an operating temperature of 300 $^{\circ}C$.

• Proceedings of the KAIS Fall Conference
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• 2011.05a
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• pp.327-331
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• 2011

Zinc oxide (5, 10 and 15 wt%) impregnated NaZSM-5 zeolite synthesized using rice husk ash as silica source was tested for $CO_2$ adsorption. The materials were characterized by XRD, SEM-EDS, $CO_2$-TPD and BET techniques. The heat of the reaction (${\Delta}$Hr) derived from DSC for ZnO(10%)/NaZSM-5 was found to be 495 Btu/lb and the maximum $CO_2$ adsorption capacity of ZnO(10%)/NaZSM-5 is 140 mg/g of sorbent. Extraction of silica from the agricultural waste, rice husk and its use in the zeolite synthesis is an added advantage in this study. Hence, from the study it is concluded that zinc oxide impregnated NaZSM-5 could be treated as novel material for $CO_2$ adsorption as they were found to be regenerable, selective and recyclable.

• 보존과학연구
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• s.14
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• pp.77-93
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• 1993

In order to study for the production techniques and the materials of using in Korean Lacquer Antiques, we examined the section structure by SEM and Microscope, the qualitative analysis of lacquer layer by XRF and XRD, the qualitative analysis of Golhae layer by XRF and XRD, the qualitative analysis of Golhae by EDS on the locquer-wares which was excavated from Anapchi Pond Site in Kyungju and Miruksa Temple Site in Iksan. In the lacquer-wares excavated from Anapchi Pond Site, the lacuqer-wares layers made by a cloth attached on the surface of wooden vessel and Golhae-a mixture of clay and lacquer-covered on the cloth and finally finished with the red lacqure, being mixed with pure mercury sulfide(HgS) and lacquer. And raw materials of Golhae made of clay. The lacquer-wares excavated from Miruksa Temple Site in Iksan, we presumed that the lacquer-wares used fine born grains in place of clay for the raw materials of Golhae. Expecially in case of black lacquer-tray, we found that lacquer put on the surface of wooden vessel without cloth attaching and Golhae covering and the production of wooden vessel was used power-driven machine.

• Corrosion Science and Technology
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• v.7 no.3
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• pp.152-157
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• 2008

New wrought magnesium alloys have increasingly been developed in recent years for the automotive industry due to their high potential as structural materials for low density and high strength/weight ratio demands. However, their poor mechanical properties and low corrosion resistance have led to a search for new kinds of magnesium alloys with better strength, ductility, and high corrosion resistance. The main objective of this research is to investigate the corrosion behaviour of new magnesium alloys: Mg-Zn-Ag (ZQ), Mg-Zn-Mn-Si (ZSM) and Mg-Zn-Mn-Si-Ca (ZSMX). These ZQ6X, ZSM6X1, and ZSM651+YCa alloys were prepared using hot extrusion. AC, DC polarization and immersion tests were carried out on the extruded rods. Microstructure was examined using optical and electron microscopy (SEM) and EDS. The addition of silver decreased the corrosion resistance. The additions of silicon and calcium also affected the corrosion behaviour. These results can be explained by the effects of alloying elements on the microstructure of Mg-Zn alloys such as grain size and precipitates caused by the change in precipitation and recrystallisation behaviour.

• 보존과학연구
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• s.27
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• pp.23-42
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• 2006

This study is about gilt bronze ornament, that is from Deok Cheon-Ri in Gyeong Ju, of conservation treatment process and of scientific analysis. This relic gathered with soil around the relic by Polyurethane foam. While the relic got rid of soil, Took X-rays. As the result, we decided to process reconstruction as condition that the relic was dug up. After the conservation treatment processed, we made a frame to display the relic. Investigated manufacture techniques of the relic after the conservation treatment processed, and thenexecuted scientific analysis of the relic for a chemical experiment. A analysis of the results of components for composition layers using the SEM-EDS can be briefly summarized as below; Firstly, the average contents of outer, inner and body corrosion layer have a Cu-60.9~39.3wt% and analyzed a little impurities material which is Fe-0.5wt%.Secondly, the average contents of body have a Cu-99.7wt% which was using manufactured by pure copper. Thirdly, gold layer have a mercury of 9.5wt% which indicate that layer was manufactured by mercury amalgam gilding technique.