• Korean Journal of Materials Research
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• v.2 no.5
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• pp.320-329
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• 1992

In 2Y-TZP powders calcined at temperature range of 80$0^{\circ}C$0 to 150$0^{\circ}C$, the effect of stabilization and the transformability of tetragonal phase on the tetragonal to monoclinic transformation have been investigated. The transformability of tetragonal phase in calcined powders shows maximum at the calcination temperature of 130$0^{\circ}C$. This result is explained by a combined effect of the increase of particle size and of constrained force among the particles with increasing the calcination temperature. The amount of transformed monoclinic phase with calcination temperature after quenching in liquid nitrogen, stress induction and isothermal aging at 25$0^{\circ}C$is also explained by the transformability of tetragonal phase determined by the sum of particle size effect and constraint effect.

• Journal of Korean Society for Atmospheric Environment
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• v.4 no.2
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• pp.20-27
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• 1988

A simple two stage aerosol filter sampler which allows simultaneous and fractional collection of two different-size particles, coarse and fine, was constructed and applied to the collection of Seoul atmospheric particulate for inorganic analysis. The sampler consist of two 47-mm diameter filter holder, a pneumatic pump, and a flowmeter. Filtering rate normally runs around 20$\ell$/min for 8 hrs. Using the sampler, a series of seasonal aerosol samples were collected from June 1986 to March 1988 at Yonsei University campus, Seoul and subsequently analysed for ten environmentally important metals using an atomic absorption spectrometer and an inductively coupled plasma emission spectrometer. The analysed metals are Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb, V, and Zn. The analytical results showed the following order of metal abundance; Al > Fe > Zn > Pb > Mn > Cu > V > Ni > Cr > Cd. Based upon their size distribution pattern, the analyzed matals could be clasified into two groups, those present primarily in coarse particle and those in fine particle. Fe, Al, Mn, V, and Cr belong to the former group while the rest to the latter. Most metal concentration were highest in spring or winter, and lowest in autumn. Statistical analysis showed strong correlations between Al and Fe, Pb and Zn, and Cu and Mn.

• Applied Chemistry for Engineering
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• v.16 no.3
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• pp.385-390
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• 2005

In this study, nano sized colloidal Ag was made by using a seed sol method. Colloidal Ag solution was spouted on the surface of the inorganic pigment using the hybridizer system and spray nozzle. Then, the surface of the inorganic pigment was modified by $TiO_2$ to obtain the antibacterial ability. In the manufacturing process of nano sized colloidal Ag, it was confirmed that the size of particles increased by addition of $AgNO_3$ and increased the reaction time. The antibacterial measurement of the inorganic pigment showed that the growth of fungus decreased as the reaction time was increased. After the antibacterial ability appeared, in 5~7 h of the antibacterial inoculation experiment, it was measured that the antibacterial activity was excellent at a fixed time frame. The photodecomposition of benzene using $TiO_2$ as the photocatalyst showed 60~70% efficiency in about 80 min. reaction time. It was shown that more than 90% of this efficiency was achieved in the reaction time of about 30 min.

• Journal of Conservation Science
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• v.35 no.6
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• pp.600-611
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• 2019

Yellow to reddish brown soil is generally referred to as hwangto and is used in various industries in Korea. Despite the fact that it is used as an inorganic pigment in dancheong, limited studies have been conducted on the properties of pigments associated with soil and on the mineralogical characteristics of hwangto. This study examines how the pedological and mineralogical features of hwangto affect pigment properties. Results indicate that reddish and yellowish soils have differences in terms of soil texture, mineral composition, oil absorption and stability under light. Reddish soil is mostly found in clay regions, whereas Ulleungdo hwangto is found in loam regions. Yellowish soil is mostly present in the clay loam to loam zones. whereas Haenam hwangto exists in the sandy clay loam zone. As a result of a mineralogical analysis, reddish soil is classified into the feldspar group and clay soil. The major minerals in the yellowish soils are similar however these soils differ in terms of clay mineral compositions. results of the characteristics of pigments prepared by the traditional method revealed that the average particle size is in the range of 10-20 ㎛, reddish soil has an average of 20 ml/100 g higher oil absorption than yellowish soil. In addition, reddish soil is more susceptible to discoloration and deterioration under light than yellowish soil. This study confirms that the soil and mineral characteristics of hwangto affect the physical properties and stability of produced pigments. These result can be used as basic data in future studies natural inorganic pigments using hwangto.

• Journal of Environmental Health Sciences
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• v.37 no.1
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• pp.29-43
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• 2011

The seasonal characteristics of atmospheric particulate matter (PM) were evaluated through the measurement of $PM_{10}$ (particles with an aerodynamic diameter of less than 10 ${\mu}m$) and $PM_{2.5}$ (particles with an aerodynamic diameter of less than 2.5 ${\mu}m$) collected in the downtown area of Iksan city over roughly two weeks in each season of 2004. During the sampling period, 54 samples of $PM_{10}$ and $PM_{2.5}$ were collected and then measured for mass concentrations of PM and its water-soluble inorganic ion species. The concentrations of $PM_{10}$ and $PM_{2.5}$ were highly variable on a daily time scale in all seasons, especially in fall. Annual concentrations of $PM_{10}$ and $PM_{2.5}$ were $54.7{\pm}21.6\;{\mu}g/m^3$ and $34.0{\pm}13.4\;{\mu}g/m^3$, respectively. The daily concentrations of the analyzed ions similarly showed a pronounced variation, although a difference between seasons existed. Among them, $SO_4^{2-}$, $NO_3^-$ and $NH_4^+$ were the most abundant ions in all seasons, contributing up to 32% of $PM_{10}$ and 39% of $PM_{2.5}$. The contribution of $SO_4^{2-}$ and $NO_3^-$ showed a seasonal variation, as $SO_4^{2-}$ was the highest during spring and summer and $NO_3^-$ was the highest during fall and winter. Non-seasalt $SO_4^{2-}$ and $NO_3^-$ were found to exist mainly as neutralized chemical components of $(NH_4)_2SO_4$ and $NH_4NO_3$ due to the high concentration of $NH_4^+$ in PM samples, which were a major form of airborne PM in all seasons. Seasonal characteristics of $PM_{10}$ and $PM_{2.5}$ in Iksan were described in relation to the temporal variations of daily concentration of PM and its inorganic ion species including inter-particle reactions.

• Applied Chemistry for Engineering
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• v.5 no.6
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• pp.1044-1055
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• 1994

The preparation of ZrC/SiC mixed powders from $ZrSiO_4/C$ and $ZrSiO_4/Al/C$ systems was attempted in the temperature range below $1600^{\circ}C$ under Ar or $Ar/H_2$ gas flow(100-500ml/min). The formation mechanism and kinetics of ZrC/SiC were suggested and the resultant powders were characterized. In $ZrSiO_4/C$ system, ZrC and SiC were formed by competitive reaction of $ZrO_2(s)$ and SiO(g) with carbon at temperature higher than $1400^{\circ}C$. The apparent activation energy for the formation of ZrC was approximately 18.5kcal/mol($1400-1600^{\circ}C$). In $ZrSiO_4/Al/C$ system, ZrC was formed by reaction of ZrO(g) with Al(l, g) and carbon at temperature higher than $1200^{\circ}C$, and SiC was formed by reduction-carbonization of SiO(g) with Al(l, g) and carbon at temperature higher than $1300^{\circ}C$. The products obtained at $1600^{\circ}C$ for 5h consisted of ZrC with lattice constant of $4.679{\AA}$ and crystallite size of $640{\AA}$, and SiC with lattice constant of $4.135{\AA}$ and crystallize size of $500{\AA}$. And also, the mean particle size was about $21.8{\mu}m$.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.30 no.2
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• pp.189-195
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• 2004

Carbon black have not been used as pigment material in cosmetic because of very low density and dispersity, but carbon black have applicable character as black pigment because of non-toxic, stable physico-chemical property, and black colority. In this study, mesoporous silica samples were synthesized by sol-gel reaction using surfactants-template method; TEOS (tetraethoxysilane) - a) PEO/lecithin, b) PEO/polyethylene glycol, c) lecithin/polyethylene glycol in ethanol/water solution. Synthesized organic-inorganic hybrid - silica were heat-treated in N2 condition at 500$^{\circ}C$. Mesoporous silica with black carbon in pore have the effective density and show the good dispersity in both hydrophilic and hydrophobic solvent. Properties of the samples were measured; specific surface area (750㎡/g) and pore size (4-6nm) using BET, pore structure (cylindrical type) using XRD, morphology (spherical powder with 0.1-0.5$\mu\textrm{m}$ partical size) of the samples using SEM. Carbon-silica black color applied to mascara, it shows a dark black colority and good dispersity as compared with the general black color titania pigment. Moreover, it is possible to control the density of black color pigment because it is possible to control pore volume and particle size of mesoporous silica properly. It show the good volume effects in mascara. That is why possible to apply all kinds of cosmetic products.

• Journal of the Korean Electrochemical Society
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• v.22 no.3
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• pp.87-103
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• 2019

Nonaqueous organic electrolyte solution in commercially available lithium-ion batteries, due to its flammability, corrosiveness, high volatility, and thermal instability, is demanding to be substituted by safer solid electrolyte with higher cycle stability, which will be utilized effectively in large-scale power sources such as electric vehicles and energy storage system. Of various types of solid electrolytes, composite solid electrolytes with polymer matrix and active inorganic fillers are now most promising in achieving higher ionic conductivity and excellent interface contact. In this review, some kinds and brief history of solid electrolyte are at first introduced and consequent explanations of polymer solid electrolytes and inorganic solid electrolytes (including active and inactive fillers) are comprehensively carried out. Composite solid electrolytes including these polymer and inorganic materials are also described with their electrochemical properties in terms of filler shapes, such as particle (0D), fiber (1D), plane (2D), and solid body (3D). In particular, in all-solid-state lithium batteries using lithium metal anode, the interface characteristics are discussed in terms of cathode-electrolyte interface, anode-electrolyte interface, and interparticle interface. Finally, current requisites and future perspectives for the composite solid electrolytes are suggested by help of some decent reviews recently reported.

• Applied Chemistry for Engineering
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• v.17 no.4
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• pp.386-390
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• 2006

Colloidal silica which has high surface area and excellent surface properties are chemically stable inorganic materials and used for various applications in industry. Silica sol was prepared from sodium silicate solution by acid neutralization method and ion exchange treatment to remove sodium ions. Through the experimental analysis for controlling factors of particle growth rate, such as temperature, pH, and aging time, the uniform size distribution of silica sol could be obtained. The size distribution and shape of silica sol was measured by TEM and dynamic light scattering method. Zeta potential change and gelling phenomena of silica sol and its rheological properties also investigated.

• KIEE International Transactions on Electrophysics and Applications
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• v.4C no.1
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• pp.26-30
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• 2004

Orientation control of a polyoxometalate (POM) nanoparticle in its two-dimensional arrangement was attempted by Langmuir-Blodgett (LB) technique. For their uniorientation, two carboxyl groups were introduced on one side of the POM particle, and hydrophobic long chains were attached by esterification with the carboxyl groups (C18-POM). The C18-POM layer spread on water surface showed stability against surface pressure up to 60 mN/m. The pattern of the C18-POM isotherm was quite different from stearyl alcohol (C18-OH), while the POM itself did not show any development of surface pressure on water surface. The AFM images of C18-POM LB films showed some microcrystalline structures that were noticed as dot structures by Brewster angle microscopy. The microimages for C18-POM did not completely spread out as a monolayer on the water surface. The XPS spectra indicated the presence of POM structures and stearyl ester bonds formed from about 65% of the total carboxyls. The XRD spectra showed that the unioriented POMs were not positioned with the same lattice distance but rather in a wavy surface state.