• Journal of the Korean Applied Science and Technology
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• v.29 no.2
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• pp.278-285
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• 2012

Effects of ion species on the expansion behavior of Poly(styrene sufonic acid)(PSSA) hydrogel were investigated in aqueous solution of selected anions, cations and hydrophobic ions. The deexpansion extent of Poly(stylene sulfonic acid) gel follow the sequence $SCN^-$<$Br^-$<$Cl^-$<$F^-$ in low concentration solutions due to the destabilization of anions to hydrogen bond between ${SO_3}^-$ and water. The deexpansion in cations followed the sequence of counterion interactions between ${SO_3}^-$ and cations. It was discussed the effects of ions on the hydrogen bonding through ${SO_3}^-$ and phenyl ring in salt solutions. Other interactions, such as the cation-${\pi}$ interaction, hydrophobic interaction, and dispersion force, contributed to the ion specific swelling of PSSA hydrogel.

• Journal of Photoscience
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• v.10 no.3
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• pp.219-223
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• 2003

Phloxine B (2,4,5,7-tetrabromo-4,5,6,7-tetrachlorofluorescein disodium salt), also referred as D&C red dye no. 28, is phototoxic to many insects such as Tephritidae fruit flies. Sunlight photolysis of phloxine B in aqueous solutions was a first order kinetic reaction at low concentrations. But it turned to be more complex reactions with the increase of phloxine B concentration. The half-lives of phloxine B (6-120 ${\mu}$M) were 18-41 and 52-289 hours in oxygenated and deaerated distilled water, respectively. The photolysis rate constants increased as the phloxine B concentrations increased. The singlet oxygen formation positively correlated with the concentrations of phloxine B and humic acid in oxygenated distilled water. The formation of singlet oxygen did not stop even after the complete degradation of phloxine B, which suggested an involvement of photoproduct-mediated reactions. The results showed that singlet oxygen mediated photooxidation was a dominant reaction for phloxine B dissipation in an aqueous solution, and the self-sensitized and photoproduct-mediated reactions were also involved at the higher concentrations. Iodide and bromide ions significantly decreased phloxine B photolysis rate constants, which were in relation to the decrease of singlet oxygen formation.

• Journal of the Korean Chemical Society
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• v.38 no.5
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• pp.351-358
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• 1994

The spectrophotometric determination of trace selenium(Ⅳ) using its catalytic reaction has been studied in aqueous solutions. The catalytic reaction of phenylhydrazine hydrochloride with selenium(Ⅳ) in an acidic aqueous medium produces benzenediazonium ion which will be converted into a red-coloured azo dye by coupling with H-acid(8-amino-1-naphtol-3,6-disulfonic acid disodium salt). For the reaction, the experimental conditions such as amounts of the reagents and pH of the sample solutions were optimized. After 15 ml of the sample solution was treated with 1 ml of 0.1 M EDTA solution to mask $Fe^{3+}$, etc., 1 ml of 0.06 M phenylhydrazine hydrochloride, 1 ml of 0.02 M H-acid, and 3 ml of 0.3 M-$KClO_3$ were added into the solution, sequentially. The solution was adjusted to pH 1.4 with HCl. After it was heated in a steam bath for 30 minutes, the solution was cooled down to a room temperature and then diluted to 25 ml with deionized distilled water. A blank solution for the absorbance measurement was prepared from the deionized water. The absorbance was measured at 527 nm. Using the above procedure, the trace amount of selenium was determined in natural waters such as tap, river and pond waters by a standard curve method and recoveries of Se spiked to samples were also obtained. From the recoveries of 104 to 111%, it could be concluded that this method was applicable to the quantitative determination of ng/ml level of selenium in natural waters.

• Applied Biological Chemistry
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• v.43 no.4
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• pp.253-259
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• 2000

In order to study the effects of the maturing temperature of kanjang(Korean traditional soy sauce) mash on the distributions of chemical compositions and sensory characteristics of kanjang, test kanjang mash prepared by mixing one part of meju and three parts of 20% salt solutions was matured at 15, 30 and $45^{\circ}C$ for 60 days respectively. It was found that although the higher the maturing temperature upto $45^{\circ}C$ for 60 days of maturing the higher total nitrogen, total free amino acids and pigment content in kanjang could be obtained, better quality kanjang containing the lower acetic acid, butyric acid and pyroglutamic acid with the higher ratio of the glutamic acid to the total free amino acids and the higher sensory evaluation scores could be prepared by maturing kanjang mash at $15^{\circ}C$.

• Membrane Journal
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• v.28 no.5
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• pp.361-367
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• 2018

In this study, the nanofiltration (NF) composite membranes for the low pressure use were prepared using polyvinylidene fluoride (PVDF) hollow fiber membrane as a supporter. Poly styrene sulfonic acid (PSSA) and polyethyleneimine (PEI) were coated onto the PVDF membrane by both layer-by-layer and salting-out methods. To characterize the prepared NF membranes in terms of the flux and salt rejection, 100 mg/L feed solutions of NaCl, $MgCl_2$, and $CaSO_4$ were used at the flow rate of 1 L/min and the operating pressure of 2 bar at room temperature. The NF membranes coated with 20,000 ppm PSSA (ionic strength 1.0) solution for 3 minutes and then 30,000 ppm (ionic strength 0.1) solution for 1 minute were observed the best performance. The permeability and salt rejection were 38.5 LMH, 57.1% for NaCl, 37.9 LMH and 90.2% for $MgCl_2$ and 32.4 LMH and 54.6% for $CaSO_4$, respectively.

• Tribology and Lubricants
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• v.31 no.6
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• pp.251-257
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• 2015

Heavy oil production is receiving significant attention because of increased demands for thermal power generation systems of the diesel engine and boilers. However, asphaltene, which is a heavy oil components (6-8 wt%), reduces the heat efficiency of the fuels owing to its agglomerated sludge of asphaltene during the burning process. Therefore, for hassle-free operation, we should develop asphaltene dispersants to suppress the formation of the sludge. We prepare variable salt-type polymeric dispersants using poly(isobutenyl succinic anhydride) and poly(amine) through both condensation esterification and acid-base neutralization reactions, which we subsequently evaluate for dispersing performance, using Turbiscan measurement. Total acid number (TAN) and total base number (TBN) of 75Lec-25SynDis.2 composed of lecithin and the prepared polymeric salt having the ratio of 3 : 1 are 18.9 and 33.7 mg KOH/g, respectively, which are comparable to those of the commercial dispersants (15.8 and 26.5 mg KOH/g). We determine the initial turbidity observed for 15 min of the polymeric dispersant was determined with transmittance (%), which can be calculated to separability number (SN). The SN value of 75Lec-25SynDis.2 is close to zero, which is superior to that of commercial dispersants and lecithin (0.015 and 0.017).

• Biomolecules & Therapeutics
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• v.4 no.4
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• pp.419-427
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• 1996

To solubilize practically insoluble biphenyl dimethyl dicarboxylate (DDB), which has been used for the treatment of chronic hepatitis as tablets or hard capsules, the solubilities of DDB in various hydrophilic, oily and hydrocarbon vehicles, and aqueous surfactant solutions were measured by high performance liquid chromatography. It was found that, among the vehicles studied, polyethylene glycol (PEG) 300 revealed the best solvency, and the solubility reached 17.6 mg/ml at 37$^{\circ}C$. The addition of glycyrrhizic acid ammonium salt (GAA) to DDB-PEG 300 solution (5-20 mg/g) inhibited the formation of precipitates, and at the concentration of 10 mg/g, any precipitaction was not observed even after 2 years at 4$^{\circ}C$. Furthermore, GAA markedly enhanced the permeation of DDB through the rabbit duodenal mucosa in a concentration dependent manner. The addition of copolyvidone (ca. 1.0%) to DDB-GAA-PEG 300 system (1 : 0.5 97.5 w/w) was most effective in preventing the considerable precipitation of DDB-PEG 300 solution (7.5 mg/750 mg) when mixed with water of 300-900 ml at 37$^{\circ}C$. GAA showed a synergistic effect in the prevention of precipitate formation. This finding suggests that this DDB formulation may form less precipitation when DDB soft capsules disintegrate and diffuse into the gastrointestinal fluid, resulting in improving the bioavailability Dissolution rate of DDB (7.5 mg) from sort elastic capsules of DDB-GAA-PEG 300 system was rapid. The supersaturation state was maintained for 2 hr at the concentration of 7.35$\pm$3.3 mg in 900 ml of water without precipitation. The total amount of DDB dissolved from this new formulation was 5.3 and 6.1 times higher, when compared to marketed DDB tablets (25 mg) and capsules (7.5 mg), respectively.

• Journal of the Korean Applied Science and Technology
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• v.24 no.4
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• pp.399-409
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• 2007

Characteristics of polyaniline anti-corrosive coatings with various primer coating resins(epoxy resin, urethane resin, and others) and top coating resins(epoxy and acrylic urethane resins) were investigated through adhesion, acid resistance, alkaline resistance, water resistance, and anti-corrosion tests. As a result, the anti-corrosive properties of the prepared coatings using polyaniline varied with the types of primer and top coating resins. In this condition, the properties of adhesion, chemical resistance, and water resistance were found to be very satisfactory when using emeraldine base (EB) of polyaniline blended with single-packaged urethane and acrylic urethane resins as the primer coatings, and using acrylic urethane resin as the top coatings. Also, the anti-corrosive function of these anti-corrosive coatings was well preserved for 1000 hr in the salt spray experiment.

• Journal of the Korean Applied Science and Technology
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• v.15 no.3
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• pp.47-53
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• 1998

The polyimide film surface was modified with KOH aqueous solutions or sulfuric acid. The film thickness was increased by about 10% through the modification of film surface. Hydrolysis of amide bonds and hydration of water induced the increase. The polarity of the film surface increased and identified by contact angle measurement. The depth and roughness of modified was increased. After treatment of surface with water, alkyl and 4-pentyloxyaniline were introduced on the film surface by complex formation between anionic species formed on the imide surface and ammonium ion. The newly introduced alkyl group was identified by FT-IR spectroscopy. Surface polarity reduced dramatically and the roughness was increased after introduction of ammonium salt.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2003.10a
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• pp.371-374
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• 2003

The corrosion of steel reinforcing bar(re-bar) has been the major cause of the reinforced concrete deterioration. FRP(Fiber-reinforced polymer) reinforcing bar has emerged as one of the most promising and affordable solutions to the corrosion problems of steel reinforcement in structural concrete. In this study, long-term durability performance of FRP re-bar were evaluated. The mechanical and durability properties of two type of CFRP- and GFRP re-bar were investigated; the FRP re-bars were subjected to alkaline solution, acid solution, salt solution and deionized water. The mechanical and durability properties were investigated by performing tensile and short beam tests. Experimental results confirmed the desirable resistance of FRP re-bar to aggressive chemical environment.