• Journal of the Korean Applied Science and Technology
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• v.26 no.2
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• pp.191-198
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• 2009

We have tested the stability of paeoniflorin, a new cosmetic ingredient, extracted from the roots of Paeoniae lactiflora. The stability of aqueous paeoniflorin solution at pH 3, 5 and 7 varied by adding buffer solution was tested at $0^{\circ}C,\;25^{\circ}C,\;40^{\circ}C,\;and\;65^{\circ}C$. The test was performed with or without UV light. The solution of paeoniflorin was stable at pH 3.0, however, the recovery rate of paeoniflorin was 40% at pH 7.0. The stability of paeoniflorin solution was decreased as the pH of paeoniflorin solution was increased by pH 7.0. The effect of storage temperature of paeoniflorin solution shows that the stability of paeoniflorin solution was decreased as the temperature was increased. The stability of paeoniflorin was rather good under UV light than the condition given above $40^{\circ}C$. The stability of paeoniflorin in W/O emulsions shows similar pattern to that of aqueous solution.

• Journal of Korean Society on Water Environment
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• v.33 no.2
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• pp.211-218
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• 2017

This experiment was carried out with the purpose of testing cadmium adsorption abilities of multi wall carbon nanotube (MWCNT), activated carbon, and synthesized layered double hydroxide (LDH). In the acidic condition, only MWCNT was effective for removing cadmium ion in the aqueous phase while other adsorbents rarely removed it. The MWCNT and cadmium ion adsorption reactions followed pseudo-first order kinetic. When the initial pH value was neutral (pH = 7), cadmium ion was rapidly removed by MWCNT and activated carbon in 4 hr (100% and 99.2%, respectively). Increasing adsorbent dosages affects the pH evolution and cadmium ion removal (0 to 99%). Cytotoxicity test showed that both MWCNT and LDH has low cytotoxic effects on three kind of human cells (A549, HS-294t, and HT-29).

• Journal of the Korean Ceramic Society
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• v.29 no.1
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• pp.74-82
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• 1992

Ultra-fine calcium phosphate powders were synthesized by the reaction of Ca(OH)2 suspension with various phosphoric aqueous solutions such as (NH4)2HPO4, H4P2O7 and H3PO4, and the characterization of powders was examined for each synthetic condition. When (NH4)2HPO4 and H3PO4 were used, hydroxyapatite powders with poor crystallinity were obtained. In the case of H4P2O7, amorphous calcium phosphate was obtained up to 0.3 mol/ι Ca(OH)2 suspension, but above the concentration, poor crystalline hydroxyapatite was produced. Crystalline phases of powders heat-treated at 80$0^{\circ}C$ were hydroxyapatite, $\beta$-tricalcium phosphate and $\beta$-tricalcium phosphate for the case of (NH4)2HPO4, H4P2O7 and H3PO4, respectively. SEM observation revealed that the shapes of synthesized powders were vigorously agglomerated spherical with the size below 100 nm, but TEM observation revealed that primary shapes of particles were rod for (NH4)2HPO4 and H3PO4 and were sphere for H4P2O7. There was no dependence of the concentration of Ca(OH)2 suspension. In the case that reaction temperature and pH of the suspension were raised, the inclination to the hydroxyapatite were remarkable. The amorphous calcium phosphate synthesized in this experiment contained water about 20% , and was crystallized to $\beta$-tricalcium phosphate at 69$0^{\circ}C$.

• The Korean Journal of Food And Nutrition
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• v.11 no.6
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• pp.595-599
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• 1998

A batch experiment was conducted to evaluate the removal capacity of welsh onion(Allium fistulosum L.), shallot (Allium ascalonicum L.), garlic (Allium sativum L.) roots as an adsorbent for Ni and Pb in aqueous solution. One gram of the dried Allium root powder was reacted in 100ml of solution containing 10mg of each heavy metal and effects of metal concentration, pH, temperature, and size of adsorbent on the removal efficiency were evaluated. The results were as follows ; The amount of adsorption of heavy metal ions were higher with the smaller particles size of adsorbent. Garlic root was high adsorption capacity of Pb, especially. The higher concentration of heavy metal solution was, the more amount of adsorption of heavy metals was. The adsorption ratio was differed from a kind of heavy metal. As the temperature increased, the amount of adsorption of Ni and Pb by shallot and welsh onion were decreased. The amount of adsorption of Ni was high under alkali conditions but the amount of adsorption of Pb was high under neutral and acidity condition.

• Journal of the Korean Chemical Society
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• v.34 no.4
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• pp.352-359
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• 1990

An effecient gas chromatographic method is described to be used routinely for the rapid profiling and identification of biochemically important organic acids. It involves the solid-phase extraction of organic acids from aqueous samples using Chromosorb P as the solid sorbent and diethyl ether as the eluting solvent, with subsequent triethylamine treatment. The resulting triethylammonium salts of acids were directly converted to volatile tert-butyldimethylsiyl derivatives, which were simultaneously analyzed by two capillary columns of different polarity, DB-5 and DB-1701, under the identical temperature programming condition. The retention index (RI) and area ratio (AR) values of each peak measured on DB-5 and DB-1701 enabled rapid identification of acids by computer RI library search and AR comparison. The application of the present method to the organic acid profiling of various complex samples is demonstrated.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.673-678
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• 2009

This paper presents the optimization process of liquid desiccant cooling cycle using LiCl aqueous solution as a working fluid. Operating conditions and design factors for heat exchangers were optimized by response surface method. As a result, we obtained the 7.297 kW of cooling capacity and 0.788 of COP at optimized condition. Effect of $dT_{hw}$ on system performances was also examined. As $dT_{hw}$ increases, the cooling capacity increases and COP decreases.

• 한국지구물리탐사학회:학술대회논문집
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• 2003.11a
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• pp.618-623
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• 2003

Solvent extraction experiments for separation of impurities from Ni-rich solution were carried out for manufacturing of high purity Ni compounds from acid leaching solution of spent Ni-Cd secondary battery. Artificial and leaching solutions were used as aqueous phases and PC88A saponified by sodium in kerosene were used as organic phase. The extraction order is Zn>Mn>Co>Ni and extraction percentage of metal ions was increased with increase of the concentration of extractant, initial pH of aqueous phase and ratio of O/A. The separation of cobalt, zinc and manganese from nickel was effectively accomplished at the condition of extraction stage=l, O/A=1 and initial pH 5.0 with 1.0 $mol/dm^3$ PC88A saponified to $50\%$ with NaOH.

• Textile Coloration and Finishing
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• v.10 no.4
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• pp.1-6
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• 1998

It is important in the durable water and oil repellent finishing for wool fabric what kinds of water-repellent agents will be used. Water repellent agents and its concentration were aleady chosen in the previous paper, one of the crosslinking agents which has less damages(harsh handle or yellowing) to the treated fabrics was a low molecular weight urethane-based resins(eg. Elastron BN-11). In repellent finishing, fabrics were padded in a bath which contained aqueous solution of water-repellent agents, and crosslinking agents, and wetting agents, followed by drying and curing. The most suitable treating condition for excellent repellency and durability to dry-cleaning was as follows ： Fabrics are padded at liquor pick-up ratio of 50%, with aqueous solution which contained $30g/\ell$ of water-repellent agents, and $1g/\ell$ of crosslinking agents, and 40g/s of wetting agents. And the padded fabrics were dried at $110^\circ{C}$ for 1 minute, and cured at $160^\circ{C}$ for 1 minute. For the fabrics, water and oil repellencies and durability to repeated dry-cleanings were observed. For enhancing the durability to dry-cleaning, the role of crosslinking agents was important for they bonds water-repellent agents and fibers to 3-dimensional net structure. Therefore, the most suitable drying and curing conditions should be selected according to the kinds of crosslinking agents.

• Journal of the Korean Ceramic Society
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• v.41 no.3
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• pp.242-246
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• 2004

Nano-sized a-alumina with a narrow distribution was prepared by using Flame Spray Pyrolysis (FSP). The microemulsion of water in oil (W/O) was prepared to make ultrafine droplets for FSP process. Kerosene (fuel) as a continuos phase and Al(NO$_3$)$_3$$.$9$H_2O$ (oxidizer) aqueous solution as a dispersed phase were prepared for microemulsification. The microemulsion with dispersion stability was obtained by adjusting the composition of 80 vol% kerosene, 10 vol% aqueous solution, and 10 vol% emulsifying agent. Microemulsion was sprayed onto the flame by using two-fluid nozzle spray gun under the condition of 0.03 ㎫ air pressure. The synthesized products were $\alpha$-alumina phase with the size of 20 to 30 nm.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2003.11a
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• pp.103-108
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• 2003

A method to determine chromium(III) ion in aqueous solution by chemiluminescence method using a lucigenin entrapped silica sol-gel film has been studied. An optical probe for chromium(III) ion has been prepared by entrapping lucigenin into silica sol-gel film coated on a glass support by dip coating. The chromium(III) optical sensor is based on the catalytic effect of chromium(IIII) ion on the reaction between lucigenin and hydrogen peroxide in basic solutions. The effects of Nafion, DMF and Triton X-100 were investigated to find the optimum condition to minimize cracking and leaching from the probe. The effects of pH and concentrations of lucigenin and hydrogen peroxide on the chemiluminescence intensity were investigated. The chemiluminescence intensity was increased linearly with increasing chromium(III) concentration from $2.5{\times}10^{-4}$M to $8.0{\times}10^{-7}$M and the detection limit was $4.0{\times}10^{-7}$M.