• Journal of Korean Society for Atmospheric Environment
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• v.19 no.4
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• pp.415-425
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• 2003

A single particle analysis, called low-Z electron probe X-ray microanalysis was applied to characterize the atmospheric aerosols collected during Asian Dust storm events in the year of 2000 and 2001. Most frequently encountered chemical species were the soil-originated species such as aluminosilicates, silicon dioxide, and calcium carbonate. Also various species such as carbon -rich, organics, sea salts, and some reacted calcium carbonate were identified. The observation of internally mixed particles oi calcium carbonate, calcium nitrate and/or calcium sulfate shows the occurrence of the heterogeneous reaction between Asian Dust particles and NO$_{x}$ and/or SO$_{x}$ species in the atmosphere.ere.

• YAKHAK HOEJI
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• v.31 no.2
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• pp.45-51
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• 1987

Methyl orange(MO) and cetyltrimethylammonium bromide(CTA) were mixed and added to 10ml of the buffer solution and then the solution was shaken for 5 minutes. The maximum absorption wavelength of the reaction product was 419nm. Dichloromethane was the best extracting solvent among the several organic solvents and the most suitable pH range was 2~8. When the CTA-MO calibration curve was made in the best experimental condition, the Lambert-Beer's law was obeyed in the range of CTA concentration of $1.5\times$$10^{-5}$~1.0$\times$$10^{-4}M$ by UV spectrophotometer. This method was possible to determine quaternary ammonium salts in the pharmaceutical preparations.

• Journal of Powder Materials
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• v.11 no.6 s.47
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• pp.467-471
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• 2004

In order to fabricate a high density sintered body of ITO, nano-sized ITO powders were synthesized by coprecipitation methods. Aqueous solutions of indium and tin salts were mixed and coprecipitated by changing their pH. Coprecipitated ITO powders possessed 20-30 nm crystallite size and a relatively high BET value ($35m^2/g$), however, aggregation of particles were occurred. Therefore, a novel recrystallization technique was applied in order to eliminate the aggregates. The recrystallized ITO material consists of a little bit larger needlelike crystals, $20nm{\times}80nm$, and it possesses a higher BET value $(57m^{2}/g)$ compared to the plain coprecipitated material $(35m^{2}/g)$. Metastable phase formation and higher content of aggregated particles were observed in the coprecipitated materials. Densification was 95% to 98% complete after 5 hour sintering at $1500^{\circ}C$ for the recrystallized powders while densities of the coprecipitated powders were below 75%.

• Journal of Plant Biotechnology
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• v.30 no.2
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• pp.185-188
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• 2003

In order to enhance shoot elongation and rooting of Anthurium andreanum 'Atlanta' in vitro, 15mL of liquid media containing various concentrations of activated charcoal, sucrose and MS salts were added in same vessels after small shoots were induced from the calli on mudium supplemented with 10.0mg/L BA and 0.1mg/L 2.4-D. The post-supplying of 15mL liquid medium containing MS macro and micro elements, 30g/L sucrose and 5.0∼10.0g/L activated charcoal was significantly stimulated the shoot elongation and rooting of regenerated shoots from calli. The medium addition was also resulted in the enhanced soil survival, elongation and rooting of plantlets in cultural soil mixed with perlite and vermiculite(1 : 1)

• YAKHAK HOEJI
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• v.35 no.1
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• pp.15-21
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• 1991

Quaternary amines which are widely used as medicines are nitrogen compounds. Metanil yellow(MY) and benzalkonium chloride(BKC) were mixed and added to 10ml of the buffer solution and then the solution was shaken for 5 minutes. The maximum absorption wavelength of the reaction product was 402 nm. Dichloromethane was the best extracting solvent among the several organic solvents and the most suitable pH range was 2~8. When the BKC-MY calibration curve was made in the best experimental condition, the Lambert-Beer's law was obeyed in the range of BKC concentration of 2$\times$$10^{-6}$~9$\times$$10^{-6}$M by UV spectrophotometer. This method was possible to determine quaternary ammonium salts in the pharmaceutical preparation.

• Carbon letters
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• v.2 no.2
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• pp.91-98
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• 2001

Porous carbons have been prepared from different parts of banana stems using two different routes, viz., by pyrolysing the mass at different temperatures as well as by treating the dried mass with chemicals followed by pyrolysis. The pyrolysis behaviour of all these materials has been studied up to $1000^{\circ}C$. Samples treated with acids exhibit more increase in surface area as compared to those treated with alkalies or salts. Analysis of BET surface area shows that the carbon prepared at low temperature shows mixed porosity, i.e., micro and mesopores. Samples heated to high temperature above $700^{\circ}C$ show decrease in macroporosity and increase in microporosity. Liquid adsorption studies have been made using methylene blue and heavy oil. The activated carbons so prepared exhibit higher oil adsorption mainly in the macro and mesopores.

• Bulletin of the Korean Chemical Society
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• v.18 no.11
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• pp.1153-1158
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• 1997

The powder characteristics of LiMn2O4 prepared by the citrate sol-gel method have been investigated. The optimum pH for the preparation of homogeneous citrate gel was calculated by the theoretical consideration of thermodynamic equilibrium constants for metal-citrate complexes and metal salts. The obtained citrate gel was prefired at 300 ℃ and calcined at 300-700 ℃ for 1 h. The obtained powders were characterized by TG/DSC, FT-IR spectrometer, X-ray diffractometer, SQUID magnetometer, SEM, and particle size analyzer. It was observed that the mixed phases of spinel LiMn2O4 and Mn3O4 were transformed into spinel LiMn2O4 phase and the vibrational bands due to the carbonate and nitrate were also disappeared over 400 ℃. At temperatures below 150 K, inverse molar susceptibilities of every sample began to show an antiferromagnetic ordering of Mn magnetic moments.

• Journal of Korea Soil Environment Society
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• v.3 no.1
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• pp.65-74
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• 1998

To enhance the washing efficiency of soil polluted by hydrophobic organic compounds, the effects of electrolytes and monomeric organic additives on micelle formation and washing efficiency of mixed surfactant solutions were investigated in this study. The surface tensions and critical micelle concentrations(CMCs) of the single and mixed surfactant solutions[$POE_5$/SDS] supplemented by NaCl were measured to investigate the effects on washing efficiency, and the composition ratios of surfactants and NaCl were optimized for the efficient soil washing system. As the mixing ratio of $POE_5$/SDS was increased to 80%, the mixed surfactant with 0.01M NaCl showed more proportional increase of washing efficiency than the mixed surfactant without any salts. The 3% solution of $POE_5$ and SDS(80%/2o%) with 0.01M NaCl showed the washing efficiency of 90%. However, the washing efficiency was not enhanced by NaCl addition to the single surfactant solution of $POE_5$. The CMC of SDS(0.049%) was higher than that of $POE_5$(0.016%), but the CMCs of mixed surfactants were decreased as the mixing ratio of $POE_5$ was increased. Alcohols having longer chain and branched carbon chain were found to be desirable for the soil washing additives.

• Analytical Science and Technology
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• v.26 no.1
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• pp.11-18
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• 2013

Perchlorate ($ClO{_4}^-$) is the material that is used as propellants of rockets and material of explosive as a form of ammonium perchlorate salts. Ammonium perchlorate solution of high concentration is recovered from expired rocket through demilitarization process by the water-jet method. If people take perchlorate in food and water, it interferes with adsorption of iodide which is the substance needed to synthesize thyroid hormone in the thyroid gland. It has an bad influence upon disturbing pregnancy and synthesis of growth hormone. So the effective method is necessary to remove perchlorate anion in water. By considering economic aspect, we studied effective desorption (regeneration) of perchlorate anion from adsorbent with studies on removal and adsorption of perchlorate anion. Desorption experiment was conducted as batch type. Depending on various conditions (concentration, pH, cation anion form) elution, we evaluated amount, efficiency of desorption(amount of adsorption/desorption ${\times}$ 100). Also, research confirmed the efficiency of mixed resins between anion exchange resin and activated carbon and expected synergic effect from advantages of both adsorbents.

• Journal of the Korean Ceramic Society
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• v.30 no.4
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• pp.325-331
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• 1993

Aqueous solutions of metallic salts, ZrO(NO3)2.2H2O and Y(NO3)3.5H2O were used as raw materials to synthesize crystalline submicron spherical powders of Zr0.94Y0.06O1.97 with tetragonal crystal phase. Each aqueous solution was mixed on the magnetic stirrer to homogenize for 12 hours. The concentration of the mixed solutionwas changed from 0.01mol/$\ell$ to 0.1mol/$\ell$ calculated as the concentration of Zr0.94Y0.06O1.97. Ultrafine droplets of starting mixed solution were sprayed by the ultrasonic vibrator and carried into the furnace kept at 55$0^{\circ}C$, $650^{\circ}C$, 75$0^{\circ}C$ and 85$0^{\circ}C$ using carrier gas of air (10$\ell$/min) and pyrolysed to form Y-TZP fine powders. The results of this exeriment were as follows. 1) Synthesized powders were nonagglomerated and spherical type. 2) Particle size distribution was narrow between 0.1${\mu}{\textrm}{m}$ and 1${\mu}{\textrm}{m}$. 3) Forming reaction Y-TZP was finished above synthetic temperature 75$0^{\circ}C$. 4) As the synthetic temperature rised from 55$0^{\circ}C$ to 85$0^{\circ}C$, the mean particle size decreased from 0.35${\mu}{\textrm}{m}$ to 0.22${\mu}{\textrm}{m}$ in the concentration of starting solution with 0.02mol/$\ell$. 5) At 75$0^{\circ}C$ of synthetic temperature, the concentration changes of starting solution from 0.01mol/$\ell$ to 0.1mol/$\ell$ increased the mean particle size from 0.24${\mu}{\textrm}{m}$ to 0.38${\mu}{\textrm}{m}$. 6) Chemical compositions of each synthesized particle were homogeneous nearly.