• Journal of the Korean institute of surface engineering
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• v.34 no.5
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• pp.391-394
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• 2001

A new type plasma reactor is proposed to decompose CF4 diluted with N2 gas in atmospheric pressure. The arc plasmas is surrounded with a waterwall which acts as a source of water vapor, the solvent of HF, resultant product after decomposition, and conveyer to take away fluorine compound from exhaust gas. Abatement more than 99% is achieved by small size plasmas such as 1 cm in diameter, 25cm in length and 3.4KW of DC discharge power in such gas as the mixture of 100 sccm of CF4 and 15 slm of N2. Reactors of this type are to be expanded to such a system as Nitrogen flow of 50 slm with 200 sccm of CF4 and 7-8 KW discharge power.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.174-174
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• 2006

By condensing two different functional monomers, highly fluorescent aromatic polymers were prepared to produce a conjugated- conjugated spacer-type copolymer or conjugated-non-conjugated spacer-type copolymer. As synthesized polymers were soluble in an organic solvent and showed significantly enhanced optical properties compared to its monomer. Variation in the monomer composition afforded polymers having multifunctionaility such as photochromic-fluorescent polymers. Transparent thin films of the polymer as a solid medium were prepared using spin coating method and fabricated as a photoswitch, which showed photo-induced conductivity switching properties depending on the core monomeric unit in the polymers.

• Bulletin of the Korean Chemical Society
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• v.15 no.10
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• pp.836-841
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• 1994

The polymer matrix effect on the selectivity, response rate and reproducibility for coextraction type anion-selective optode membranes were investigated with DOA-plasticized PVC, PVC/hydroxylated PVC, PU/hydroxylated PVC and DOS-plasticized CTA matrices. Optode membranes were prepared with TDMACl and ETH2412 dissolved in one of the four solvent polymeric matrices. The PU/hydroxylated PVC and PVC-based membranes have almost the same selectivity coefficients, while the CTA-based membrane is more selective toward lipophilic anions. The membrane with PU/hydroxylated PVC adhered strongly to a glass surface, and showed highly reproducible and relatively rapid response. Very poor adhesion of PVC/hydroxylated PVC and CTA-based membranes limited the usability of those membranes as sensor components. Based on these results, and considering the biocompatibility for clinical samples, the optode made with PU/hydroxylated PVC was applied to determine the thiocyanate ion in human saliva. The results obtained with this simple device were comparable to those with rather complicated ISE methods.

• Journal of the Korean Applied Science and Technology
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• v.15 no.1
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• pp.99-108
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• 1998

Novel type surfactants containing two long-chain hydrophobic alkyl groups and two hydrophilic sulfonate groups were successfully synthesized by reactions of ethylene glycol diglycidyl ether with long-chain fatty alcohols, after then by reactions with 1,3-propane sultone and sodium hydride under THF solvent. All these compounds, so called Gemini surfactants, were purified by thin layer chromatography and column chromatography. Their structures were identified by FT-IR and $^{1}H$-NMR.

• Membrane Journal
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• v.3 no.3
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• pp.117-125
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• 1993

The CA reverse osmosis membranes were prepared and were studied the effects of parameters in membrane performance. The dope solutions were composed of polymer, formamide, acetone and 2-methoxyethanol. And it was prepared flat type membranes. The membranes were measured flux and rejection. The experimental factors such as polymer concentration, additive type, solvent evporation period, annealing temperture, and applied pressure were changed to investigate the effects of these on the membranes. And the transport parameters were also calculated at reverse osmosis medel for prepared membranes.

• Carbon letters
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• v.16 no.1
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• pp.51-56
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• 2015

Carbonate-type organic electrolytes were prepared using propylene carbonate (PC) and dimethyl carbonate (DMC) as a solvent, quaternary ammonium salts, and by adding different contents of 1-ethyl-3-methyl imidazolium tetrafluoroborate ($EMImBF_4$). Cyclic voltammetry and linear sweep voltammetry were performed to analyze conducting behaviors. The surface characterizations were analyzed by scanning electron microscopy method and X-ray photoelectron spectroscopy. From the experimental results, increasing the $EMImBF_4$ content increased the ionic conductivity and reduced bulk resistance and interfacial resistance. In particular, after adding 15 vol% $EMImBF_4$ in 0.2 M $SBPBF_4$ PC/DMC electrolyte, the organic electrolyte showed superior capacitance and interfacial resistance. However, when $EMImBF_4$ content exceeded 15 vol%, the capacitance was saturated and the voltage range decreased.

• Analytical Science and Technology
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• v.17 no.6
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• pp.481-488
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• 2004

Solvent extraction of Ni(II) into a chloroform by using salen[N,N'-Bis (salicylidene)-ethylenediamine] as a ligand has been studied. Salen was synthesized from ethylenediamine and salicylaldehyde by simple condensation reaction in an ethanol. Salen formed a 1 : 1 complex with Ni(II) and its extraction constant was $10^{5.12}$. For the determination of Ni(II) in sea water samples, some experimental conditions such as pH of solution, amount of salen, acid type and concentration for back extraction, extraction time, and influence of foreign ions were optimized by using a synthetic sea water. The sea water of which the composition was similar to a natural sea water was synthesized in this laboratory. Trace Ni(II) was extracted into the chloroform in the weak basic solution above pH 8. And the nickel could be quantitatively extracted with the concentration of salen higher than $1.2{\times}10^{-4}mol/L$. This concentration was more than 180 times of Ni(II) in the solution with a mole ratio. Real samples of Korean coastal sea water were analyzed under optimized conditions. Even though Ni(II) was not detected in these samples. Recoveries more than 98% were obtained in the samples which 40 ng/mL of Ni(II) was spiked. And detection limit of proposed method was 1.3 ng/mL. From these results, it could be known that salen of this type would be applied for the determination of trace metals as an organic chelating reagent.

• Applied Chemistry for Engineering
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• v.18 no.2
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• pp.188-193
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• 2007

Semi-solvent type cleaning agents were prepared by mixing naphthenes, natural terpene oil, surfactant and water, and measured their physical properties. And also, cleaning efficiency for flux and grease was measured by gravimetric method. By measuring the physical properties, pH for cleaning agents were 6.0~6.7, surface tension, 27.4~28.4 dyne/cm, and wetting index, 8.65~12.46 (with water), 11.99~17.43 (without water). The cleaning agent composed of naphthene, 30 wt%, natural terpene oil, 45 wt%, surfactant, 13 wt%, co-surfactant, 12 wt%, and water, 0 wt% had the largest wetting index, and shown the most effective cleaning properties for flux (98.66%) and grease (93.44%). The conductivity with $0.5{\sim}0.9{\mu}s/cm$ to the cleaning agent containing small amount of water was found to form W/O type microemulsion.

• Journal of the Korean Applied Science and Technology
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• v.41 no.2
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• pp.508-519
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• 2024

In this study, in order to evaluate the possibility of using Jubak as a functional cosmetic material, evaluation of antioxidant activity according to fractions and anti-wrinkle efficacy in CCD-986sk cells, a human fibroblast, were conducted. As a result of confirming the antioxidant activity by measuring ABTS⁺ radical scavenging ability, Jubak's Ethyl Acetate fractions was found to be 75.5% at a concentration of 1,000 ㎍/ml, showing the highest antioxidant activity among the extraction solvents. The wrinkle improvement effect was confirmed by measuring the inhibitory activity of elastase and collagenase, and in both test results, Jubak's Ethyl Acetate fractions showed the highest efficacy at a concentration of 1,000 ㎍/ml. As a result of measuring the synthesis rate of pro-collagen type I in CCD-986sk cells induced by UVB, Jubak showed the highest efficacy in the order of Ethyl Acetate, Water, Acetonitrile, and Hexan fractions at the same concentration of 20 ㎍/ml. As a result of measuring the inhibition rate of MMP-1, a collagen degrading enzyme, all four solvent fractions showed an efficacy of more than 70% at 20 ㎍/ml. As a result of measuring the mRNA expression levels of pro-collagen type I, MMP-1, and MMP-3 in a real-time PCR experiment, the protein expression level of pro-collagen type I increased when treated with Jubak fractions compared to the UVB group alone. The mRNA expression levels of MMP-1 and MMP-3 were confirmed to be decreased, and Ethyl Acetate fractions was the most effective in improving wrinkles after the control group (EGCG). As a result, it was confirmed that the Ethyl Acetate fractions among Jubak's solvent fractions has an anti-wrinkle effect against photoaging caused by UVB stimulation, and is expected to be used as a natural material for cosmetics.

• Restorative Dentistry and Endodontics
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• v.35 no.5
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• pp.321-334
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• 2010

Objectives: The purpose of this study is to evaluate bonding efficacy by means of measuring the effect of remained solvent on Degree of conversion(DC) and ${\mu}TBS$ and FE-SEM examination. Materials and Methods: Two 2-step total etching adhesives and two single-step self etching adhesives were used in this study. First, volume weight loss of 4 dentin adhesives were measured using weighting machine in process of time in normal conditions and calculate degree of evaporation (DE). Reaction/reference intensity ratio were measured using micro-Raman spectroscopy and calculate DC according to DE. Then 2 experimental groups were prepared according to air-drying methods (under, over) and control group was prepared to manufacturer's instruction. Total 12 groups were evaluated by means of micro tensile bond strength and FE-SEM examination. Results: Degree of evaporation (DE) was increased as time elapsed but different features were observed according to the kind of solvents. Acetone based adhesive showed higher DE than ethanol and butanol based adhesive. Degree of conversion (DC) was increased according to DE except for $S^3$ bond. In ${\mu}TBS$ evaluation, bond strength was increased by additional air-drying. Large gaps and droplets were observed in acetone based adhesives by FE-SEM pictures. Conclusions: Additional air-drying is recommended for single-step self etching adhesive but careful consideration is required for 2-step total etching adhesive because of oxygen inhibition layer. Evaporation method is carefully chose and applied according to the solvent type.