• Korean Journal of Food Science and Technology
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• v.36 no.1
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• pp.58-63
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• 2004

Cell-separating enzymes were used to investigate enzymatic maceration of watermelon and muskmelon containing single cells. Watermelon and muskmelon were macerated with Macerozyme A and Sumyzyme MC for 30-120min. Changes in maceration properties such as yields, color, viscosity, total sugar, total pectin, total polyphenol, particle size distribution, minerals, and free amino acids of suspensions after enzymatic disintegration were investigated. Contents of biochemical components in the supernatant of suspensions increased with increasing treatment time. Suspensions containing single cells showed good thermal stability without affecting original qualities. Mineral content of single-cell suspension was higher than those of watermelon and muskmelon juices. Potassium contents of single-cell suspension and juice were 240.8 and 172.7 mg%, respectively. Results suggest single-cell suspensions of watermelon and muskmelon can he utilized as ingredients for new beverages.

• YAKHAK HOEJI
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• v.36 no.6
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• pp.538-547
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• 1992

Optimal synthetic condition of barium sulfate were investigated from the viewpoint of yield and bulkiness according to a randomized complete block design proposed by G.E.P. Box and K.B. Wilson. Barium chloride and magnesium sulfate were utilized as reactants in order to prepare barium sulfate in this study. It was found that optimum temperature range of reactant solutions was $60{\sim}100^{\circ}C$ and the optimum concentration range of the reactant solutions was $10{\sim}17.3%$ and $10{\sim}20%$ respectively, on the viewpoint of yield and bulkiness. The optimum mole ratio of $BaCI_2$ to $BaSO_4$ was in the range of $1.50{\sim}2.0$ and the optimum mole ratio of $BaCI_2$ to $BaSO_4$ was in the range of $1.50{\sim}2.0$ and the optimum reacting time range was $15{\sim}20$ minutes. The optimum drying temperature range was $110{\sim}130^{\circ}C$ from the viewpoint of yield, but it was $90{\sim}110^{\circ}C$ on the basis of bulkiness. Apparent viscosity of barium sulfate suspensions dispersed in various concentrations of Na. CMC was measured by using Brookfield synchrolectric viscometer model LVT, the relative equation, log ${\eta}_{sp}=A+B.{\phi}$ was examined and the equation was found to agree fairly well. 1 w/v% Na. CMC aqueous solution and 0.1 volume fraction of $BaSO_4$ powder were optimum in the preparation of $BaSO_4$ suspension showing highest viscosity at infinite shearing.

• Journal of the Korean Ceramic Society
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• v.56 no.4
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• pp.360-364
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• 2019

PZT suspensions for photo-curable 3D printing were fabricated and their characteristics were evaluated. After mixing the PZT, photopolymer, photo-initiator, and dispersant for 10 min by using a high-shear mixer, the viscosity characteristics were investigated based on the powder content. To determine an appropriate dispersant content, the dispersant was mixed at 1, 3, and 5 wt% of the powder and a precipitation test was conducted for two hours. Consequently, it was confirmed that the dispersibility was excellent at 3 wt%. Through thermogravimetric analysis, it was confirmed that weight reduction occurred in the photopolymer between 120? and 500?, thereby providing a debinding heat treatment profile. The fabricated suspensions were cured using UV light, and the polymer was removed through debinding. Subsequently, the density and surface characteristics were analyzed by using the Archimedes method and field-emission scanning electron microscopy. Consequently, compared with the theoretical density, an excellent characteristic of 97% was shown at a powder content of 87 wt%. Through X-ray diffraction analysis, it was confirmed that the crystallizability improved as the solid content increased. At the mixing ratio of 87 wt% powder and 13 wt% photo-curable resin, the viscosity was 3,100 cps, confirming an appropriate viscosity characteristic as a stereolithography suspension for 3D printing.

• Journal of Microbiology and Biotechnology
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• v.14 no.6
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• pp.1129-1133
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• 2004

The effects of Pluronic F-68, a non-ionic surfactant, on the growth and physical characteristics of Digitalis lanata suspension cultures were investigated in aqueous two-phase systems (ATPSs) composed of $4.5\%$ polyethylene glycol (PEG) 20,000 and $2.8\%$ crude dextran. In the range of 0.1-10.0 g $1^{-1}$, Pluronic F-68 enhanced the maximum cell density in a medium with ATPSs, even though Pluronic F-68 did not affect cell growth in a normal growth medium. In terms of physical properties of ATPSs with cell suspension cultures, 0.2 g $1^{-1}$ of Pluronic F-68 reduced viscosity by up to $40\%$, while 0.1 g $1^{-1}$ of Pluronic F-68 significantly enhanced the oxygen transfer rate. In addition, we successfully performed aqueous two-phase cultivation in a 5-1 stirred tank bioreactor with 0.5 g $1^{-1}$ of Pluronic F-68, and discovered that cell growth in ATPSs was similar to that in normal growth medium.

• Korea-Australia Rheology Journal
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• v.18 no.4
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• pp.171-181
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• 2006

We present a short review for authors' previous work on direct numerical simulations for inertialess hard particle suspensions formulated either with a Newtonian fluid or with viscoelastic polymeric fluids to understand the microstructural evolution and the bulk material behavior. We employ two well-defined bi-periodic domain concepts such that a single cell problem with a small number of particles may represent a large number of repeated structures: one is the sliding bi-periodic frame for simple shear flow and the other is the extensional bi-periodic frame for planar elongational flow. For implicit treatment of hydrodynamic interaction between particle and fluid, we use the finite-element/fictitious-domain method similar to the distributed Lagrangian multiplier (DLM) method together with the rigid ring description. The bi-periodic boundary conditions can be effectively incorportated as constraint equations and implemented by Lagrangian multipliers. The bulk stress can be evaluated by simple boundary integrals of stresslets on the particle boundary in such formulations. Some 2-D example results are presented to show effects of the solid fraction and the particle configuration on the shear and elongational viscosity along with the micro-structural evolution for both particles and fluid. Effects of the fluid elasticity has been also presented.

• Korean Journal of Optics and Photonics
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• v.15 no.5
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• pp.449-454
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• 2004

The optical limiter is an optical component which reduces laser beam intensity for the protection of eyes and light sensors. Carbon nanotube is now known as a highly efficient optical limiting material. Optical limiting effect of the multi-walled carbon nanotube suspensions, in several kinds of solvents such as distilled water, chloroform, ethanol and ethylene glycol, were measured in the range from room temperature to near to the boiling points of the solvents. The pulsed Nd:YAG laser whose wavelength is 1064 nm and pulse duration is 6 ns was used as a light source. The experimental result shows that the limiting efficiency was reduced as the temperature increased, and the suspension which has lower boiling point, viscosity and surface tension has highest efficiency.

• Journal of radiological science and technology
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• v.26 no.1
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• pp.39-44
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• 2003

The aim of this study is to evaluate a efficient w/v% barium suspension and w/v% sodium carboxy methyl cellulose (SCMC) for small bowel examination. Between november 2001 and june 2002, 370 patients were examined small bowel examination with oral administration of barium suspension mixed with SCMC. we classified into six groups including A(fine type 40% $BaSO_4$ mixed 0.5% SCMC and 600 ml 0.5% SCMC administration), B(fine type 30% $BaSO_4$ mixed 0.5% SCMC), C(fine type 20% $BaSO_4$ mixed 0.5% SCMC), D(fine type 25% $BaSO_4$ mixed 0.5% SCMC), E(D mixed coarse type 25% $BaSO_4$ mixed 0.5% SCMC), F(D mixed coarse type 25% $BaSO_4$ mixed 0.75% SCMC). We measured transparency rate of contrast media transit time, administration dose, viscosity and particle size. The transparency rate was higher then 80 kV and 90 kV in 100 kV in the same 20 mAs condition. Transit time was the fastest in A group(mean trans time 56 minutes) and the slowest in E group(mean 100 minutes), Administration dose was the smallest in A group(mean dose 541 ml and the most in E group(mean 1,100 ml), viscosity was the lowest in E(125.1 mpa/s) and the highest in A(375.5 mpa/s), and particle size was $1.0\;{\mu}m$ in A, B, C, and D group, $0.6\;{\mu}m,\;1.0\;{\mu}m,\;10.0\;{\mu}m$ in E, F group. In conclusion, we propose that the efficient condition for small examination is high voltage technique, high density $BaSO_4$, and 0.625% w/v SCMC.

• Polymer(Korea)
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• v.30 no.6
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• pp.505-511
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• 2006

We tried to prepare polystyrene composite particles containing carbon black by suspension polymerization with water as a reaction medium. Hydrophobic silica was selected as a stabilizer and oil-soluble azobisisobutyronitrile (AIBN), as an initiator. All polymerization reactions were carried out at a fixed temperature of $75^{\circ}C$. Stabilizer concentration was varied from $0.17{\sim}3.33wt%$ compared to water, where particles with $7.96{\mu}m$ in average diameter were obtained at 1.57 wt% of stabilizer. Increase in divinylbenzene concentration, as a crosslinking agent, from $0.1{\sim}1.0 wt%$ compared to monomer exhibited a large increase in average particle diameter Incorporation of 1wt% of carbon black compared to monomer produced an increase in average diameter It is speculated that viscosity lower than that necessary to induce even dispersion of carbon black particles led to poor dispersion, and as a result, large particles. For a styrene mixture containing 3 wt% carton black compared to monomer, enhanced dispersion due to an increase in carbon black concentration reduced average particle diameters. For styrene mixtures containing 1 and 3 wt% carbon black compared to monomer, preparticles before polymerization and polymer composite particles after polymerization showed a similar tendency towards particle formation. When carbon black concentration compared to monomer was increased to 5 and 7 wt%, styrene mixtures exhibited a large increase in viscosity and thus better dispersion of carbon black particles, which led to a decrease in preparticle diameters. However, these particles experienced agglomeration in the polymerization process, and polystyrene composite particles increased in average diameter.

• Korean Journal of Food Science and Technology
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• v.36 no.5
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• pp.693-700
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• 2004

Viscometry was applied to identify irradiated corn starch (CS), sweet potato starch (SS), and potato starch (PS) from non-irradiated controls using Brookfield DV-III programmable rheometer. Effects of starch suspension concentration (7.0-9.5%) and spindle speed (25-125 rpm) were investigated. Established optimal viscosity-measuring conditions showed the highest correlation coefficient between irradiation dose (0-6.0 kGy) and corresponding viscosities for CS, SS, and PS. Threshold values for identifying irradiated starches were suggested. Viscosities of all samples significantly decreased with increasing irradiation dose (p<0.05) and spindle speed, while increased as suspension concentration increased. Optimal conditions for suspension concentration and spindle speed were 7.5% (6.7%, d.b.) and 125rpm in CS, 8.5% (7.3%, d.b.) and 125 rpm in SS, and 9.0% (7.3%, d.b.) and 100rpm in PS, respectively. Under these measuring conditions, threshold values for discriminating unknown samples were 0.313, 0.345, and 0.811 for CS, SS, and PS in 1.5 kGy-irradiated samples, compared with 0.521, 0.798, and 1.693 in non-irradiated samples, respectively, enabling identification of irradiated from non-irradiated starches.

• Tribology and Lubricants
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• v.14 no.2
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• pp.42-48
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• 1998

Electro-Rheological (ER) fluid is a class of functional fluid whose apparent viscosity can be varied by the applied electric field strength. The ER fluid is classified into two types; one is a dispersive fluid and the other is a homogeneous. Dispersive ER fluid is a colloidal suspension of fine semiconducting particles in a dielectric liquid and liquid crystal (LC) is classed as homogeneous type ER fluid. LC has been originally developed for some electronic display devices. Various mechanical components applying ER fluid have been developed, and the their performance typically depends on the characteristics of ER fluid which have generally been evaluated by a rotational viscometer. However, the ER fluid introduced into various mechanical components undergoes not only simple shear flow but press flow or oscillating flow. For the evaluation of ER fluid, the authors developed an reciprocating type viscometer. The amplitude is controlled on 5 mm at the frequency from 50 to 1000 Hz. In the present paper, the performance of several types of ER fluid is evaluated by the reciprocating type viscometer and compared with those evaluated by a rotational viscometer.