• Journal of the Korean Chemical Society
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• v.43 no.2
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• pp.172-181
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• 1999

To develop the manufacturing technique for the powder builder of amorphous solid types, the water glass mixed with caustic soda dispersed into the methanol. Thus soluble sodium silicate was made a form of amorphous solid powder. In order to examine characteristics of water soluble sodium silicate $SiO_2/Na_2O$ mol ratio, we investigated solubility, thermogram, SEM, and BET analysis. pH buffering capacity, calcium-ion binding capacity as temperature change, and surfactant loading capacity were examined for characteristics as laundry detergent builder. $SiO_2/Na_2O$ molar ratio of soluble sodium silicate was 1.0, 2.4, 2.8, and zeolite was used in order to investigate basic characteristics of laundry detergent builder. Silicate used with laundry detergent was good for pH buffering capacity and solubility. But calcium-ion binding capacity and surfactant adsorption ability were lower. $SiO_2/Na_2O$ mol ratio became higher, pH buffering capacity and ion exchange ability were lower and surfactant adsorption ability was a little higher.

• Korean Chemical Engineering Research
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• v.54 no.5
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• pp.587-592
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• 2016

Sodium borohydride, $NaBH_4$, shows a number of advantages as hydrogen source for portable proton exchange membrane fuel cells (PEMFCs). Properties of $NaBH_4$ hydrolysis reaction using unsupported Co-P-B Co-B, catalyst at high concentration $NaBH_4$ solution were studied. In order to enhance the hydrogen generation yield at high concentration of $NaBH_4$, the effect of catalyst type, $NaBH_4$ concentration and recovery of condensing water on the hydrogen yield were measured. The yield of hydrogen evolution increased as the boron ratio increased in preparation process of Co-P-B catalyst. The hydrogen yield decreased as the concentration increased from 20 wt% to 25 wt% in $NaBH_4$ solution during hydrolysis reaction using 1:5 Co-P-B catalyst. Maximum hydrogen yield of 96.4% obtained by recovery of condensing water and thinning of catalyst pack thickness in reactor using Co-P-B with Co-B catalyst and 25 wt% $NaBH_4$ solution.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.1
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• pp.60-68
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• 2011

[ $ZrO_2-TiO_2$ ]binary oxides with various Zr:Ti molar ratios were prepared by sol-gel method and Nafion$^{(R)}$/$ZrO_2-TiO_2$ composite membranes were fabricated for proton exchange membrane fuel cells (PEMFCs) at high temperature and low humidity. Water uptake, Ion exchange capacity (IEC), and proton conductivity of Nafion$^{(R)}$/$ZrO_2-TiO_2$ composite membranes were characterized and these composite membranes were tested in a single cell at $120^{\circ}C$ with various relative humidity (R.H.) conditions. The obtained results were compared with the unmodified membranes (Nafion$^{(R)}$ 112 and Recast Nafion$^{(R)}$). A Nafion$^{(R)}$/$ZrO_2-TiO_2$ composite membrane with 1:3 of Zr:Ti molar ratio showed the highest performance. The performance showed 500 mW/$cm^2$ (0.499V) at $120^{\circ}C$, 50% R. H., and 2 atm.

• Journal of the Korean Electrochemical Society
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• v.3 no.1
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• pp.57-62
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• 2000

Sulfonated Polysulfone (SPSF) cation-exchange membranes were synthesized by introducing various ratio of chlorosulfuric acid (CSA) onto the main chain of polysulfone (PSF). Properties such as ion exchange capacity, water content, liked ion concentration, and partition coefficient were measured, respectively. Through the analysis of DSC and TGA, it has been shown that glass transition temperature increased and weight loss decreased as sulfuric acid group concentration increased. Structure of membrane measured by AFM and SEM was seen to be asymmetric. Apparent diffusion coefficient of sodium ions through SPSF membrane by AC impedance was increased as sulfuric acid group concentration increased.

• Polymer(Korea)
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• v.25 no.6
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• pp.765-773
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• 2001

In In order to remove harmful trace elements such as $Co^{2+}$, $Ni^{2+}$ , $Cr_2O_7\;^{2-}$ from water, we synthesized AN-co-(MMA/IA) according to various mole ratio of monomers and spun by wet-spinning. And multi-functional PAN ion exchangers were prepared by hydrolysis. We observed structure, degree of functionalization, ion exchange capacity, distribution coefficient and mechanical properties for ion exchanger. Anion exchange capacity decreased in 4.5 ~ 4.2 meq/g with increasing of IA content and cation exchange capacity increased in 1.8 ~ 2.2 meq/g. Tensile strength of the ion exchanger increased up to 0.008 mol% IA content and appeared maximum value by 216$kg/cm^2$Distribution coefficient for AN-co-(MMA/IA) ion exchanger appeared maximum value for Co(II), Ni(II) in pH 5-6 range and for Cr(III) in pH 3-4 range. And the adsorption capacity was in the order of Cr(III) > Co(II) > Ni(II) for multicomponent in continuous process.

• Journal of the Microelectronics and Packaging Society
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• v.9 no.2
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• pp.19-25
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• 2002

Glass composed of $Li_2$O.MgO. $MgF_2$.$SiO_2$.$B_2O_3$ for the fabrication of green sheet was prepared by melting process, and glass ceramics was prepared by the process of nucleation and grystal growth for the glass of $Li_2$O.MgO. $MgF_2$.$SiO_2$.$B_2O_3$ system with Lithium fluorhectorite and Lithium boron fluorphlogopite crystal phase. Powderization of the glass ceramics was carried out by water swelling. The average particle size at this point was 2.574 $\mu\textrm{m}$. Slurry was prepared for green sheet using high viscous sol fabricated by water swelling, which shows cleavage phenomenon in prepared glass ceramics. The optimum ratio of powder to water for the tape casting was 18:100, and its viscosity was 11,000~14,000 cps.

• Macromolecular Research
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• v.14 no.5
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• pp.573-578
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• 2006

Three different, polymer-platinum conjugates (hydrogels, microparticles, and nanoparticles) were synthesized by complexation of cis-dichlorodiammineplatinum(II) (cisplatin) with partially succinylated glycol chitbsan (PSGC). Succinic anhydride was used as a linker to introduce cisplatin to glycol chitosan (GC). Succinylation of GC was investigated systematically as a function of the molar ratio of succinic anhydride to glucosamine, the methanol content in the reaction media, and the reaction temperature. By controlling the reaction conditions, water-soluble, partially water-soluble, and hydrogel-forming PSGCs were synthesized, and then conjugated with cisplatin. The complexation of cisplatin with water-soluble PSGC via a ligand exchange reaction of platinum from chloride to the carboxylates induced the formation of nano-sized aggregates in aqueous media. The hydrodynamic diameters of PSGC/cisplatin complex nano-aggregates, as determined by light scattering, were 180-300 nm and the critical aggregation concentrations (CACs), as determined by a fluorescence technique using pyrene as a probe, were $20-30{\mu}g/mL$. The conjugation of cisplatin with partially water-soluble PSGC, i.e., borderline between water-soluble and water-insoluble PSGC, produced micro-sized particles $<500{\mu}m$. Cisplatin-complexed PSGC hydrogels were prepared from water-insoluble PSGCs. All of the cisplatin-incorporated, polymer matrices released platinum in a sustained manner without any significant initial burst, suggesting that they may all be useful as slow release systems for cisplatin. The release rate of platinum increased with the morphology changes from hydrogel through microparticle to nanoparticle systems.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.609-611
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• 2004

Sodium salt of photoluminescent Eu-containing polyoxometalate (Eu-POM) was newly synthesized and its chemical structure and physical properties characterized. The Eu-POM was unstable outside the pH range 5.5-8.5, and a pH just over 7 gave the best yield. We have investigated the photoluminescent properties of Eu-POM with changing the reactants ratio of heteropolytungstate and $EuCl_3{\cdot}6H_2O}$. The Eu-POM was characterized by UV/Vis, FT-IR, $^1H$-NMR, PL and XPS. Eu-POM emits orange light of 590nm when excited with the light of 280nm. Furthermore, we made dodecyltrimethylammonium (DDTA) salt of Eu-POM (Eu-POM/DDTA) by exchange of the counter cation. The Eu-POM/DDTA is soluble in common organic solvents, while Eu-POM is only soluble in water. And it emits reddish orange light of 625nm when excited with light of 250nm.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2002.04a
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• pp.18-23
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• 2002

Liquid phase mixing of impinging injector is a resultant byproduct from the momentum exchange between a pair of impinging jets and penetration of opponent jet. Principal aim of the present study is revealing the liquid phase mixing mechanism of split triplet impinging injection sprays, and thus extending our understanding on this particular injection element. Overall mixing extent is estimated from patternation tests by the use of purified tap water and kerosene to simulate the real propellant components, respectively, and with the liquid jet momentum ratio, a controlling mixing parameter, in the range of 0.5 to 6.0. Emphasis is placed on the effect of liquid sheet superposition and disintegration, and the results with detailed spray visualization revealed the fact that superposed liquid sheet disintegration is the main pathway of liquid phase mixing of split triplet impinging injector to yield enhanced mixing qualities.

• Natural Product Sciences
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• v.4 no.2
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• pp.88-90
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• 1998

An acid polysaccharide (SFP), was extracted from alga Sargassum fusiforme in hot water, was purified by ion exchange chromatography on DEAE-cellulose. The PC, chemical analysis, electrophoresis and IR of SFP indicated that it was a kind of alginate with a mol. wt. of 13,000 and a molar ratio of mannuronic acid to guluronic acid 2.75. Pharmacological tests showed that SFP could prolong the survival duration of mice suffering from ascitic Sarcoma 180 with a rate of life prolongation of 63.44%.