• Bulletin of the Korean Chemical Society
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• v.35 no.2
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• pp.466-470
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• 2014

In this paper, organic solvent electrolytes were prepared by a mixture of propylene carbonate (PC), dimethyl carbonate (DMC), tetraethylammonium tetrafluoroborate ($TEABF_4$)s to evaluate the ionic properties of propylene carbonate (PC)/dimethyl carbonate (DMC) mixtures as solvents for a capacitor application, in view of improving the electrochemical performances. The bulk resistance and interfacial resistance of the mixture electrolytes were investigated using an AC impedance method. The morphology of carbon-based electrodes which were contained in different electrolytes was analyzed by scanning electron microscopy (SEM) method. From the experimental results, by increasing the FEC content, capacitance of electrodes was increased, and the interfacial resistance was decreased. In particular, by a content of 2 vol % FEC in 0.2 M $TEABF_4$ PC/DMC solvent, the electrolyte showed the superior capacitance. However, when FEC content exceeds 2 vol %, the capacitance was decreased and the interfacial resistance was increased.

• Journal of the Korean Electrochemical Society
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• v.18 no.4
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• pp.150-155
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• 2015

In this study polymer electrolytes containing ethylene carbonate group which have a high dielectric constant and poly(ethylene glycol) as branches were prepared by the Williamson reaction between poly(ethylene glycol) methyl ether and block copolymers composed of glycerol-1,2-carbonate and 4-chloromethyl styrene. Interestingly, the highest ionic conductivity of $1.75{\times}10^{-5}S\;cm^{-1}$ was observed from the polymer electrolyte having 7 mol% of ethylene carbonate and the [EO]:[Li] ratio of 32:1. Moreover, it was found that the electrochemical stability of polymer electrolyte was achieved up to 5.5 V because of the presence of ethylene carbonate.

• Geomechanics and Engineering
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• v.13 no.3
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• pp.371-384
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• 2017

Physical and mechanical properties of rocks are of interest in many fields, including materials science, petrophysics, geophysics and geotechnical engineering. Uniaxial compressive strength UCS is one of the key mechanical properties, while density and porosity are important physical parameters for the characterization of rocks. The economic interest of carbonate rocks is very important in chemical or biological procedures and in the field of construction. Carbonate rocks exploitation depends on their quality and their physical, chemical and geotechnical characteristics. A fast, economic and reliable technique would be an evolutionary advance in the exploration of carbonate rocks. This paper discusses the ability of ultrasonic wave velocity to evaluate some mechanical and physical parameters within carbonate rocks (collected from different regions within Tunisia). The ultrasonic technique was used to establish empirical correlations allowing the estimation of UCS values, the density and the porosity of carbonate rocks. The results illustrated the behavior of ultrasonic pulse velocity as a function of the applied stress. The main output of the work is the confirmation that ultrasonic velocity can be effectively used as a simple and economical non-destructive method for a preliminary prediction of mechanical behavior and physical properties of rocks.

• The Journal of the Petrological Society of Korea
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• v.10 no.1
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• pp.1-12
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• 2001

A small of carbonate rocks and spatially-associated ultramafic rocks uniquely occur in the ulsan iron-serpentine mine of the sourtheastern Kyungsang basin. The study of field geology, core drilling data and stable isotope analysis suggest that the carbonate rocks are carbonatite formed from the melt reflecting intrusive natures. Based on this study, the geology of the Ulsan iron-serpentinite mining area consists of Cretaceous sedimentary, volcanic, granitic ultramafic and carbonate rocks in ascending order. The carbonate and ultramafic rocks show concentric and ellipsoidal shapes at the outcrop and a funnel shape in the cross sectional view. Carbon and oxygen stable isotope analysis show a bimodal pattern rather than a typical mantle pattern, which may indicate that the melt was a secondary melt generated within the crus not in the mantle directly. The uprising of ultramafic melts would have melted lime-contained rocks forming a secondary carbonate melt in the upper crus. Then, the intrusion of the ultramafic melts would have melted lime-contained rocks forming a secondary carbonate melt in the upper crust. Then, the intrusion of the ultramafic melt was followed by the intrusion of the carbonate melt along deep-seated fractures. Well-developed major fractures in this area, fluid inclusion characteristics of the carbonate rocks, the spatial relation between the ultramafic and carbonate rocks and stable isotope data support interpreting the Ulsan carbonate rocks as carbonatite.

• Resources Recycling
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• v.17 no.6
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• pp.10-16
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• 2008

In this study, the crystallization of cerium carbonate from cerium chloride solution by addition of ammonium bicarbonate was investigated. The concentration of reactants such as cerium chloride(0.5-2M) and ammonium bicarbonate, and reaction temperature($20-60^{\circ}C$) have a great effect on the crystal types of cerium carbonate such as lanthanite-type cerium carbonate[$Ce_2(CO_3)_3{\cdot}8H_2O$] and tengerite-type cerium carbonate[$Ce_2(CO_3)_3{\cdot}2.5H_2O$]. The crystallinity of cerium carbonate changed from lanthanite to tengerite as the concentration of reactants and reaction temperature increased. Transformation of cerium carbonate hydrate was transformed to cerium hydroxy carbonate depended on the drying conditions. Cerium carbonate of lanthanite and tengerite has the shape of aggregates with plate type crystal, and the size of lanthanite and tengerite crystal was $3{\mu}m$ and $5{\mu}m$, respectively. Cerium hydroxy carbonate has the shape of aggregates with needle type crystal, and the crystal size was about $7{\mu}m$.

• Journal of the East Asian Society of Dietary Life
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• v.26 no.6
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• pp.559-564
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• 2016

We investigated the effect of calcium carbonate on the quality of wine obtained from Gaeryangmerou (Vitis. spp.), grapes, which are commonly used in wine making in Korea. Alcoholic fermentation was carried out at $25^{\circ}C$, for 7 days in the presence of 0.1%, 0.2%, and 0.3% calcium carbonate. As calcium carbonate concentration increased, the pH of wine increased, while its total acid content and redness decreased. Calcium carbonate treatment during precipitation and aging is more effective than during fermentation. Concentrations of alcohol, total anthocyanin, polyphenol, and tannin showed no significant differences between controls and deacidified groups. Tartaric and malic acids were found to be the major acids in Gaeryangmerou wine. Calcium carbonate reduced total acidity by precipitating tartaric acid. In the sensory evaluation of the acidity, and overall acceptability, wine treated with 0.1% calcium carbonate was the best. Higher calcium carbonate concentration, was associated with greater reduction in total wine acidity. However, it is necessary to maintain the calcium carbonate concentration within 0.1% since excessive amounts of calcium carbonate can have a negative effect on wine quality.

• The Journal of Engineering Research
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• v.5 no.1
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• pp.73-87
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• 2004

The synthesis and crystallization of amorphous calcium carbonate($CaCO_3$.$nH_2 O$) obtained from gas-liquid reaction between aqueous solution of calcium hydroxide and carbon dioxide at 15~$50^{\circ}C$ are investigated by electrical conductometry, XRD and TEM. The results are as follows: The initial reaction products prior to the formation of precipitated calcium carbonate is amorphous calcium carbonate. The electrical conductivity values in the slurry are decreased during the formation of amorphous calcium carbonate which covers particle surface of calcium hydroxide and retard the dissolution of calcium hydroxide into the solution. that amorphous calcium carbonate is unstable in the aqueous solution and crystallizes finally to calcite by the through-solution reaction. While amorphous calcium carbonate crystallizes into chain-like calcite, the conductivity values are recovered rapidly and the apparent viscosity of slurry containing higher concentration of calcium hydroxide increase. At below pH 9.5, chain-like calcite separates into individual particles to form precipitated calcium carbonate. The formation and synthetic temperature range of amorphous calcium carbonate is most suitable a primary decreasing step(a-step) at $15^{\circ}C$ in the electrical conductometry.

• Korean Chemical Engineering Research
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• v.50 no.5
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• pp.908-912
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• 2012

Lauan sawdust was gasified by steam reforming for hydrogen production from biomass waste. The fixed bed gasification reactor with 1m height and 10.2 cm diameter was utilized for the analysis of temperature and catalysts effect. Steam was injected to the gasification reactor for the steam reforming effect. Lauan sawdust was mixed with potassium carbonate, sodium carbonate, calcium carbonate, sodium carbonate + potassium carbonate and magnesium carbonate + calcium carbonate catalysts of constant mass fraction of 8:2 which was injected to the fixed gasification equipment. The compositions of production gas of gasification reaction were analyzed at the temperature range from $400^{\circ}C$ to $700^{\circ}C$. Fractions of hydrogen, methane and carbon monoxide gas in the production gas increased when catalysts were used. Fractions of hydrogen, methane and carbon monoxide gas were increased with increasing temperature. The highest hydrogen yield was obtained with sodium carbonate catalyst.

• Journal of the Korean Electrochemical Society
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• v.18 no.1
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• pp.1-6
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• 2015

In this study polystyrene derivative, VBCE, having a cyclic carbonate was synthesized by Williamson reaction and polymerized to poly(VBCE) successfully in an usual polymerization conditions. The obtained polymer was blended with PEGMA and the effect of composition on the ionic conductivity was investigated. Interestingly, the ionic conductivity was decreased from $4.2{\times}10^{-5}S\;cm^{-1}$ to $3.93{\times}10^{-6}S\;cm^{-1}$ with the poly(VBCE) contents of 5.8mol%. From the DSC study, it was found that the $T_g$ of the blend was increased from $-50^{\circ}C$ to $-21^{\circ}C$ by the addition of poly(VBCE). Therefore, it is believed that the presence of a polar cyclic carbonate makes polymer matrix harder and it is necessary to design new structures less hindered the mobility of the matrix.

• Journal of the Korean Geosynthetics Society
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• v.14 no.2
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• pp.1-9
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• 2015

In this study, the objective of the study is to evaluate the effect of calcium carbonate powder, produced by the microbial reactions, on the strength of soft ground (sand). To analyze the cementation effects of calcium carbonate powder produced by microbial reactions on the strength of the sand, six different types of specimens (untreated, calcium carbonate, cement, carbonate+cement (1:9, 3:7, 5:5)) were made. The specimen were tested after curing (7 and 28 days). Uniaxial compressive strengths were measured on $D5cm{\times}H10cm$ specimens. Based on the test results, as both the weight ratio and the curing period increase, calcium carbonate, cement, and calcium carbonate+cement specimens showed an increase in the strength. In addition, compared with the strength of the specimen with cement, the strengths of the specimens with mixing ratios of 1:9, 3:7, and 5:5 (carbonate : cement) were found to be 93.5~95.8%, 825.%, 65.2~70.6%.