• Korean Journal of Materials Research
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• v.13 no.9
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• pp.572-580
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• 2003

Synthesizing behavior and microstructural evolution of $CaZrO_3$and $m-ZrO_2$in a thermal reaction process of $ZrSiO_4$-$xCaCO_3$mixtures, where x is 7 and 19, were investigated to determine the addition amount of CaO in CaO:$ZrO_2$:$SiO_2$ternary composition. CaZrO$_3$-Ca$_2$SiO$_4$precursor prepared by the mixture of $ZrSiO_4$and CaCO$_3$in aqueous suspending media was controlled to the acidic (pH=4.0) condition with HCI solution to enhance the thermal reaction. The addition amount of dispersant into the $ZrSiO_4$-$xCaCO_3$slip increased with increasing mole ratio of $CaCO_3$, which was associated with the viscosity of slip. Decarbonation reaction was activated with an increase of the addition amount of $CaCO_3$, showing different final temperatures in $ZrSiO_4$-$7CaCO_3$and $ZrSiO_4$-$19CaCO_3$mixtures as about 980 and 116$0^{\circ}C$, respectively, for finishing decarbonation reaction. The grain morphology was changed to spherical shape for all samples with an increase of sintering temperature. The grain size and phase composition of the synthesized composites depended on the mixture ratio of Zrsi04 and CacO3 powders, indicating that the main crystals were m-ZrO2 ($\leq$3 $\mu\textrm{m}$) and $CaZrO_3$ ($\leq$ 7 $\mu\textrm{m}$) in $ZrSiO_4$$>-7CaCO_3$and $ZrSiO_4$-$19CaCO_3$mixtures, respectively.

• Membrane Journal
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• v.8 no.3
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• pp.157-169
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• 1998

The effects of solvents (DMAc, NMP, 1,4-dioxane) and nonsolvents ($H_2O$, Methanol, n-hexane) on the morphology of 6FDA-p-TeMPD polyimide membrane, prepared by the wet phase inversion method, were studied. In the polymer/solvent/nonsolvent ternary system, the binodal curve, the coagulation value and the relative light transmission were measured, and the solubility parameter difference was calculated. The onset state and rate of liquid-liquid alemixing were predicted and the morphology of membrane was analyzed. It is found that the finger-like pores are formed within discontinuous polymer nodules when the binoclal curve is close to the polymer-solvent (P-S) axis, the coagulation value is small, the reduction of light transmission is easy to occur and the order of solubility parameter difference ($\Delta \delta_{i-j}$) is $\Delta \delta_{S-NS} > \Delta \delta_{P-NS} > \Delta \delta_{P-S}$. The dense skin with small nodules and the sponge type sublayer with macrovoid are formed in the case that the binodal curve is distant from the P-S axis, the onset time of liquid-liquid demixing is long and the order of $\Delta \delta_{i-j}$ is $\Delta \delta_{P-NS} >(\Delta \delta_{S-NS} < > \Delta \delta_{P-S})$. The thick layer of fine nodule coagulation and loosely grown sublayer of nodules appear when the binodal curve is distant from the P-S axis, the onset time of liquid-liquid demixing is very long and the order of $\Delta \delta_{i-j}$가 $\Delta \delta_{S-NS} > (\Delta \delta_{P-NS}$\lessgtr$ > (\Delta \delta_{P-NS} < >)\Delta \delta_{P-S}$ ).

• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.4
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• pp.287-294
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• 2019

GGBFS(Ground Granulated Blast Furnace Slag) has been widely used in concrete for its excellent resistance chloride and chemical attack, however cracks due to hydration heat and dry shrinkage are reported. In many International Standards, GGBFS with low fineness of 3,000 grade is classified for wide commercialization and crack control. In this paper, the mechanical and durability performance of concrete were investigated through two mix proportions; One (BS) has 50% of w/b(water to binder) ratio and 60% replacement ratio with low-fineness GGBFS, and the other (TS) has 50% of w/b and 60% replacement ratio with 4000 grade and FA (Fly Ash). The strength difference between TS and BS concrete was not great from 3 day to 91 day of age, and BS showed excellent performance for chloride diffusion and carbonation resistance. Two mixtures also indicate a high durability index (more than 90.0) for freezing-thawing since they contain sufficient air content. Through improvement of strength in low fineness GGBFS concrete at early age, mass concrete with low hydration heat and high durability can be manufactured.

• Korean Journal of Optics and Photonics
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• v.9 no.4
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• pp.221-226
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• 1998

Ternary heavy metal oxide glasses in the $PbO-Bi_2O_3-Ga_2O_3$ system doped with $Er_2O_3$ were prepared and their spectroscopic properties, such as radiative transition probability, calculated and measured radiative lifetimes and cross-sections of 1.5 $\mu\textrm{m}$ and 2.7 $\mu\textrm{m}$ emissions were analyzed. Enhanced quantum efficiencies of some electronic transitions were evident mainly because of the low vibrational phonon energy ($~500cm^{-1}$) inherent in the host glasses. This seems to be the main reason for obtaining the 2.7 $\mu\textrm{m}$ luminescence which is normally quenched in the conventional oxide glasses. In addition, green and red fluorescence emissions were observed through the frequency upconversion processes of the 798 nm excitation. Non-radiative transition due to the multiphonon relaxation is a dominant lifetime-shortening mechanism in the 4f-4f transitions in $Er^{3+}$ ion except for the $^4S_{3/2}{\rightarrow}^4I_{15/2}$ transition where a non-radiative transfer to band-gap excitation of the host glasses is dominant. Melting of glasses under an inert gas atmosphere and (or) addition of the typical glass-network former into glasses is necessary in order to enhance the quantum efficiency of the transition.

• Journal of the Mineralogical Society of Korea
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• v.30 no.4
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• pp.219-227
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• 2017

Manganese (Mn) nodules in the Arctic Sea have been founded in the Kara Sea and Barents Sea, but mineral and chemical compositions have been rarely investigated. In this study, mineralogical and geochemical characteristics of Mn nodules obtained during the Arctic Expedition ARA07C in northern East Siberian Sea were identified, and then genesis of Mn nodules were estimated by using these characteristics. Main manganese oxide minerals constituting the manganese nodule were buserite, birnessite, and vernadite. The Mn nodules generally represent radiated and massive texture, and the layered texture was developed restrictively. The radiated texture, main feature of the manganese nodule in the East Siberian Sea, is mainly composed of cuspate-globular microstructure. Compared with the Mn nodules in Pacific and Indian Oceans, Mn nodules of the East Siberian Sea are abundant in Mn, but Fe is too scarce. There was no difference in the chemical composition and microstructures between outer and inner part of nodule. Therefore, nodules are most likely to have only one genesis during their growth, and all of nodules indicate the diagenetic in $Mn-Fe-(Cu+Ni+Co){\times}10$ ternary diagram. It is considered that the manganese nodules in the East Siberian Sea are characterized by high Mn contents because manganese contents in the Arctic Ocean were mainly resulted from river or coastal erosion and most of them are trapped in the Arctic Ocean.

• Elastomers and Composites
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• v.41 no.4
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• pp.260-267
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• 2006

SBR (styrene-butadiene rubber; 25 wt% of solid contents) nanocomposites reinforced with OLS(organically modified layered silicates) were manufactured via the latex method. Two types of OLS are prepared, i.e. dodecylamine (primary amine) modified montmorillonite (DA-MMT) and N, N-dimethyldodecylamine (tertiary amino) modified MMT (DDA-MMT). X-ray diffraction (XRD) and transmission electron microscopy (TEM) were employed to characterize the layer distance of OLS and the morphology of the nanocomposites. SBR nanocomposites reinforced with ternary phase filler (carbon black/silica/OLS) systems also manufactured. Dynamic mechanical thermal analysis (DMTA) was performed on these composites to determine the loss factor (tan $\delta$) over a range of temperature($-20^{\circ}C{\sim}80^{\circ}C$). The results showed that there was significant changes on the values or tan $\delta$ with the addition of small amount of the OLS. By increasing the contents of OLS, the values of tan $\delta$ at $0^{\circ}C$ increased but those of tan $\delta$ at $60^{\circ}C$ decreased with increasing OLS contents.

• Korean Chemical Engineering Research
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• v.40 no.6
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• pp.703-708
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• 2002

High pressure phase behavior data for poly(propyl acrylate) and poly(propyl methacrylate) with supercritical $CO_2$, ethylene, propane, butane, propylene, 1-butene, dimethyl ether, and $CHClF_2$ were measured in the temperature range from $23^{\circ}C$ to $186^{\circ}C$ and at pressures up to 2,400 bar. The cloud point were obtained at dissolved pressure below 2,070, 1,400, 1,880, 450, 2,200, 250, and 150 bar for poly(propyl acrylate) in supercritical $CO_2$, ethylene, propane, propylene, butane, 1-buthen, and dimethyl ether, respectively. The temperature range is $23-175^{\circ}C$. The poly(propyl methacrylate) does not dissolve in $CO_2$ at temperature of $240^{\circ}C$ and pressure 2,900 bar. The poly(propyl methacrylate)-propane, poly(propyl methacrylate)-butane, poly(propyl methacrylate)-propylene, poly(propyl methacrylate)-1-butene, and poly(propyl methacrylate)-$CHClF_2$ systems were dissolved at the pressures less than 2,390 bar, below 2,100 bar, below 570 bar, below 310 bar, below 300 bar, and below 170 bar, respectively. The temperature range shows from 40 to $186^{\circ}C$. The phase behavior of between binary poly(propyl acrylate)-$CO_2$ and poly(propyl acrylate)-dimethyl ether system were measured from upper critical solution temperature region to lower critical solution temperature region with added dimethyl ether concentrations of 5, 15 and 50 wt%.

• Korean Journal of Materials Research
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• v.11 no.8
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• pp.629-635
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• 2001

To improve the ductility of $A1_3Hf$ intermetallics, which are the potential high temperature structural materials, the mechanical alloying behavior. the effect of Cu addition on the $Ll_2$ phase formation and the behavior of vacuum hot-pressed consolidation were investigated. During the mechanical alloying by SPEX mill, the $Ll_2 A1_3Hf$ intermetallics with the grain size of 7~8nm was formed after 6 hours of milling in Al-25at.%Hf system. The $Ll_2$ Phase of Al_3Hf$ intermetallics with the addition of 12.5at.%Cu, similar to that of the binary Al-25at.% Hf, was formed, but the milling time necessary for the formationof the $Ll_2$ phase was delayed form 6 hours to 10 hours. The lattice parameter of ternary $Ll_2(Al+Cu)_3Hf$ intermetallics decreased with the increase of Cu content. The onset temperature of $Ll_2$ to $D0_{23}$ phase in $Al_3Hf$ intermetallics was around 38$0^{\circ}C$, the temperature upon completion varied from 48$0^{\circ}C$ to 5$50^{\circ}C$ as the annealing time. The onset temperature of $Ll_2$ to $D0_{23}$ phase transformation in $(Al+ Cu)_3Hf$ intermetallics increased with the amount of Cu and the highest onset temperature of $700^{\circ}C$ was achieved by the Cu addition of 10at.%. The relative density increased from 89% to 90% with the Cu addition of 10at.% in $Al_3Hf$ intermetallics hot-pressed in vacuum under 750MPa at 40$0^{\circ}C$ for 3 hours. The relative density of 92.5% was achieved without the phase transformation and the grain growth as the consolidation temperature increased from 40$0^{\circ}C$ to 50$0^{\circ}C$ in $(Al+Cu)_3Hf$ intermetallics hot-pressed in vacuum under 750MPa for 3 hours.

• Journal of Soil and Groundwater Environment
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• v.14 no.4
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• pp.23-32
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• 2009

The sorption of europium (Eu (III)) onto kaolinite and the influence of humic acids over a range of pH 3 ~ 11 has been studied by batch adsorption experiment (V/m = 250 : 1 mL/g, $C_{Eu(III)}\;=\;1\;{\times}\;10^{-5}\;mol/L$, $C_{HA}\;=\;5{\sim}50\;mg/L$, $P_{CO2}=10^{-3.5}\;atm$). The concentrations of HA and Eu(III) in aqueous phase were measured by UV absorbance at 254nm (e.g., $UV_{254}$) and ICP-MS after microwave digestion for HA removals, respectively. Results showed that the HA sorption onto kaolinite was decreased with increasing pH and their sorption isotherms fit well with the Langmuir adsorption model (except pH 3). Maximum amount ($q_{max}$) for the HA sorption at pH 4 to 11 was ranged from 4.73 to 0.47 mg/g. Europium adsorption onto the kaolinite in the absence of HA was typical, showing an increases with pH and a distinct adsorption edge at pH 3 to 5. However in the presence of HA, Eu adsorption to kaolinite was significantly affected. HA was shown to enhance Eu adsorption in the acidic pH range (pH 3 ~ 4) due to the formation of additional binding sites for Eu coming from HA adsorbed onto kaolinite surface, but reduce Eu adsorption in the intermediate and high pH above 6 due to the formation of aqueous Eu-HA complexes. The results on the ternary interaction of kaolinte-Eu-HA are compared with those on the binary system of kaolinite-HA and kaolinite-Eu and adsorption mechanism with pH was discussed.

• Korean Journal of Heritage: History & Science
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• v.57 no.1
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• pp.146-159
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• 2024

In this study, a study on the production technology of the Buddha statue and the production of raw material origin was conducted through scientific analysis on the Bronze seated Bodhisattva Statue of Goseongsa Temple, a treasure. As a result of microstructure analysis through a metal microscope, it was confirmed that the microstructure of the Bronze seated Bodhisattva Statue of Goseongsa Temple was a process-type dendritic structure, and the casting structure of bronze was well represented, so it was manufactured through casting. Subsequently, as a result of analyzing the alloy composition ratio through SEM-EDS, it was identified as a ternary alloy with 81.26 wt% of copper (Cu) and 16.42 wt% of tin (Sn) and 1.72 wt% of lead (Pb). The results of the analysis of lead isotope ratios using a thermal ionization mass spectrometer (TIMS) were substituted into the distribution of lead isotope ratios on the Korean Peninsula, it was shown in corresponding to Jeolla-do and Chungcheong-do regions and North and South Gyeongsang Province. This suggests that the raw materials used in their production were likely sourced from the mines around Goseong Temple in Gangjin. Despite the fact that the statue is a medium and large Buddha with a total height of 51 centimeters, 1.72 wt% of lead (Pb) was found as a result of alloy composition ratio analysis, which showed a similar composition to the lead content ratio of small bronze and gilt-bronze Buddha statues. Therefore, we compared and analyzed the results of the analysis of the composition ratio of the alloys of bronze and gilt bronze statues, which has been scientifically analyzed with a compositional age similar to that of the Bronze seated Bodhisattva Statue of Goseongsa Temple. Comparison results, Various factors, such as the size of the Buddha statue as well as its stylistic characteristics and the age of composition, may exist in determining the alloy composition ratio of the bronze and gilt bronze Buddha statues, and it was confirmed that the alloy composition ratio or casting technology was properly adjusted when the Buddha statue was created. In other words, it is judged that a more comprehensive system of Buddha statue production technology should be investigated by conducting archaeological and art history studies on stylistic characteristics and age of composition, as well as scientific analysis results such as observation of internal structure, microstructure observation, and analysis of alloy composition ratio using radiation transmission irradiation.