• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.5
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• pp.486-491
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• 2004

Dimensionally stable anode(DSA) can be used for the hydro-metallurgy of non-ferrous metals like as Zn, and the electrolysis of sea water. MnO$_2$ electrode satisfies the requirements of DSA, and has a good cycle life and a low overpotential for oxygen evolution. MnO$_2$ electrodes based on Ti matrix were prepared by using thermal decomposition method and also MnO$_2$ was coated on Ti and Pb matrix with DMF and PVDF compositions. The MnO$_2$ electrodes prepared by thermal decomposition method had very weak adhesive strength onto Ti matrix and MnO$_2$ layer was removed out so that electrochemical properties for MnO$_2$ were not investigated. The viscosity of solvent used as a binder of MnO$_2$ Powder increased with the increasing PVDF contents. The thickness of the MnO$_2$ layer on Pb matrix in DSA, which was prepared with 5 times dipping at the solution mixed with PVDF : DMF = 1 : 9, was 150${\mu}{\textrm}{m}$. When the ratio of PVDF to MnO$_2$ was lower than 1 : 6, the Pb electrode didn't show any reaction irrespective of the concentrations of DMF. However, When the ratio of PVDF to MnO$_2$ was higher than 1: 6, the Pb electrode showed constant current reactions and homogeneous cyclic voltammetry even though at a high cycle. The reason for the high current and homogeneous cyclic voltammetry is the good catalytic reactions of MnO$_2$ powder in electrode.

• Korean Journal of Food Science and Technology
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• v.16 no.4
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• pp.451-456
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• 1984

Rheological properties of gelatinized rice starch solutions were investigated with Brookfield rotational viscometer. The 8% starch solution showed thixotropic behavior with yield stress. The alkali gelatinized starch was more thixotropic than the thermal gelatinized one. The time dependent characteristics of starch solutions followed Tiu's model. The value of rate constant $(a_1)$ in Tiu's model increased linearly with shear rate, and was exponentially dependent on concentration and temperature. Temperature dependency of rate constant and apparent viscosity followed Arrhenius type equation and the activation energy were about 14.3 and 6.8 Kcal/g mole, respectively. The $a_1-value$ was found to be useful to evaluate changes in structaral decay on the shearing time of gelatinized rice starch solutions.

• Korean Journal of Food Science and Technology
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• v.19 no.2
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• pp.102-106
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• 1987

In order to examine the appropriateness of types of pigskin as a raw material for gelatin production, comparison was made on the quality of gelatins made from raw and scalded pigskins. Raw and scalded pigskins were acidified in 1.7% HCl solution for 15-18 hr and then washed by tap water for 10 hr. After washing, pigskins were extracted at $60^{\circ}C$, $70^{\circ}C$ and $80^{\circ}C$ to produce gelatins. Gelatins from raw pigskins appeared to be better in gel strength than those from scalded ones at all extraction temperatures. Gelatin yield was higher with raw than with scalded pigskins. With the increase of extraction temperature, the decrease in gel strength and viscosity was resulted in. More colored gelatins were produced with increasing extraction temperature in both raw materials. Electrophoretic pattern of gelatins showed that higher molecular weight fractions decreased with the increase of extraction temperature and pigskin gelatin had more complicated molecular composition than that of type B gelatin (alkali-treated gelatin).

• Korean Journal of Food Science and Technology
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• v.20 no.3
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• pp.441-446
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• 1988

Alkaline treatment during preparation of anchovy extracts was studied for its changes in some of the physicochemical and sensory qualities. The dried anchovy was blended in 0-0.5N NaOH solutions and then incubated at $60^{\circ}C$ for 6 hours. After extraction the suspensions were neutralized and centrifuged. The results showed that the yields of solids and protein were increased by 3-5 fold of those of water extract as alkaline concentration and treatment time increased. The intrinsic viscosity showed little changes for the extracts prepared with 0-0.2N NaOH solution while the extracts prepared with over 0.3N NaOH resulted a initial small decrease followed by a rapid increase to the maximum point. The changes in color expressed as Hunter 'L', 'a' and 'b' values showed that the L value increased rapidly until 3 hours of treatment followed by a decrease, and 'a' and 'b' values were increased a little. The intensities of odor and taste were markedly increased by 2-3 fold for all of the descriptions investigated where clam-like odor and taste and sea complex odor were particularly significant.

• The Korean Journal of Food And Nutrition
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• v.20 no.2
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• pp.195-201
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• 2007

This study were investigated the changes in chemical components, quality characteristics of the fermented broth, and physiological functionality during fermentation period of fruit, vegetables, and medicinal herbs. pH and $^{\circ}$Bx gradually decreased and the viscosity increased. The chromaticity of L, a, and b all increased. The total number of germs dropped from $10^5{\sim}10^6\;to\;10^2{\sim}10^3$ CFU/ml, and that of lactobacilli also decreased noticeably. According to the result of the effect on fat oxidation, a very low level of TBARS was shown. After thirty days of fermentation, the amount of each fermentation broth increased more or less, but as it declined considerably after ninety days, it was found that the binding effect of $Fe^{2+}$ ion was small and insignificant. The electron donating ability, though not reaching 0.5% ascorbic acid, showed a high level of activity from $33.71{\sim}72.15%$ before fifteen days and $44.76{\sim}75.20%$ ninety days after fermentation. Among them, the fruit fermentation solution showed the highest activity. It was also found that the organic functions for each fermentation broth decreased more or less depending on the fermentation period and the thirty-days-old fermentation broth were favored most. On the basis of the above experiment results, it can be concluded that the optimum fermentation period for fruit, vegetables, and medicinal herb is thirty to ninety days.

• Korean Journal of Food Science and Technology
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• v.26 no.2
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• pp.127-132
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• 1994

Removal of viscous materials, mainly alginate, from sea tangle extracts by $CaCl_2$ precipitation or ultrafiltration was investigated. The sea tangle extracts were prepared by enzymatic hydrolysis of polysaccharides followed by 2 hours of boiling in 1.5% NaCl or 2.0% sucrose solution. The $CaCl_2$ precipitation resulted in higher amount of total solid, amino-nitrogen and mannitol than those values of ultrafiltration, but protein extracted was less in the former. Both methods caused a significant decrease in the viscosity and turbidity of the extracts. The composition of four nucleotides showed that UMP and IMP were not detected in $CaCl_2$ precipitated extracts, while ultrafiltered extracts showed a fairly even distribution of them. Removal of viscous material, particularly ultrafiltration increased the glutamic acid in amino acid composition and reduced serine, histidine, lysine, glycine, phenylalanine and leucine.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.3
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• pp.47-55
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• 2013

Curved duct channel flow characteristics for non-Newtonian gel fluid is investigated. A simulant gel propellant mixed by Water, Carbopol 941 and NaOH solution has been chosen to analyze the gel propellant flow behavior. Rheological data have been measured prior to the flow analysis where water-gel propellant and water-gel propellant with $Al_2O_3$ nano particles are both used. The critical Dean number examined by the numerical simulation in the U-shape duct flow reveals that although water-gel-nano propellants have higher apparent viscosity, the critical Dean number do show no notable difference for both the two gel propellant. It is found that the power-law index may be a dominant parameter in determining the critical Dean number and that the gel with particles addition may be more vulnerable to Dean instability.

• Polymer(Korea)
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• v.36 no.5
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• pp.628-636
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• 2012

The polymer concentration dependence of depletion layer was investigated by means of dynamic light scattering after the very small amount of polystyrene spherical latex particles was added into the matrix solution of poly(vinyl alcohol)(PVA)/dimethyl sulfoxide. At the dilute regime, the magnitude of depletion layer kept constant at the level of $63{\pm}3%$ of the radius of gyration of the corresponding PVA chain. Next, at the early semi-dilute regime of $1.5{\leq}C[{\eta}]{\leq}3$, polymer concentration dependence of the layer thickness ${\delta}$ was obtained as ${\delta}{\sim}C^{-0.8}$, and this experimental value was very close to theoretical one of -0.75. However it was observed above $C[{\eta}]$ >3 that its thickness decreased abruptly, and this was ascribed to aggregation effect of latex particles which was driven by Oosawa type attractive interaction.

• YAKHAK HOEJI
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• v.41 no.1
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• pp.48-59
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• 1997

Sustained release matrix tablets, pellets, and coated pellets for the delivery of sulindac were prepared using cellulose derivatives at various ratios, and evaluated for the dis solution pattern. The release of sulindac, from matrix tablets prepared with low viscosity HPMC was relatively fast, and especially the tablets made of Metolose SM released all of sulindac within 1 hr. The release of drug from tablets made of other HPMC derivatives were retarded in the order of the following: Pharmacoat 645>Pharmacoat 606>Pharrnacoat 606+HPC-L>HPC-L. The most sustained release pattern was observed with the preparation of high viscous polymer. Metolose 90 SH. While release of sulindac, from matrix type pellet containing 10mg/cap of Metolose 90 SH or 60 SH was completed within 1 hr, a prolonged release formulation (30% in 1 hr) was obtained by the inclusion of EC. Pellets coated with HPMC showed a fast release pattern (${\geq}$ 80% within 2 hrs), whereas pellets coated with HPMC and EC (molar ratio 1 : 1) showed a sustained release pattern (${\geq}$ 80% in 12 hrs), vath the release from EC pellets being the most sustained. Fast (naked) and slow release pellets coated with EC, Metolose 60SH 50cps and propylene glycol. and enteric pellets coated with HPMCP 55 and Myvacet$^{\circledR}$ were prepared, and combined at various ratios for the assessment of dissolution pattern. The result indicates the possibility that the development of 24 hr sustained release delivery systems containing sulindac for oral administration could be achieved by means of combining sustained and fast release pellets at a proper portion.

• Corrosion Science and Technology
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• v.7 no.5
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• pp.283-287
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• 2008

The drag reduction agency (DRA) for gas pipeline, a novel method used for reducing friction or drag on a gas flowing to increase the transmission efficiency of gas pipeline, is a more flexible and economical technology than internal flow efficient coatings. In this paper, an effective DRA has been developed in Authors' Institute by analyzing the hydrodynamic friction resistance on internal gas pipeline and then studying the work mechanism and molecular structure of DRA. In the meantime, a group of property test for selecting DRA material has been determined, including viscosity, contact angle, volatility, corrosion, slab extending, and flow behavior in horizontal tube. The inhibition efficiency and drag reduction efficiency of the developed DRA have been investigated finally based on the relevant test methods. Results of corrosion test show that the developed DRA has very good inhibition effect on mild steel by brushing a thin layer of DRA on steel specimens, giving inhibition efficiency of 91.2% and 73.1% in 3%NaCl solution and standard salt fog environment respectively. Results of drag-reducing test also show that the Colebrook formula could be used to calculate friction factors on internal pipes with DRA as the Reynolds number is in the range of $0.75\times10^5\sim2.0\times10^5$. By comparing with normal industrial pipes, the friction resistance coefficient of the steel pipe with DRA on internal wall decreases by 13% and the gas flux increases by 7.3% in testing condition with Reynolds number of $2.0\times10^5$.