• Korean Journal of Food Science and Technology
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• v.14 no.4
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• pp.315-323
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• 1982

The measurement of cell constant in a diaphragm-cell method is the most important factor. In order to get the correct cell constant, the diffusion coefficients of potassium chloride were measured, at various concentration and temperature of potassium chloride solution, and at the stirring rate in the cell. The pseudo-binary diffusion coefficients of organic aroma component (benzaldehyde) in sugar solution has been measured at various concentration and temperature with the cell constant obtained above. Experimental results were compared and discussed with the semi-empirical epuations from literatures. And, especially, the diffusion coefficient of benzaldehyde, $D_{ba}$ for a small solute diffusing in a viscous solvent of larger molecules is proportional to the -0.82 power of the viscosity of aqueous sugar solution, ${\mu}$ at constant temperature, $D_{ba}{\mu}^{0.82}=constant$.

• Korean Journal of Food Science and Technology
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• v.7 no.4
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• pp.212-220
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• 1975

Cooking and eating qualities of two rice varieties in Korea, an Indica type 'Tongil' and a Japonica type 'Jinheung', were investigated to compare each other. Cooked rice of Tongil variety absorbed $4{\sim}6%$ more water at the same water-to-rice ratio, showed higher mechanical hardness and needed 20% higher water-to-rice ratio to maintain the same hardness as compared with Jinheung variety. Optimum water-to-rice ratios in cooking were shown to be 140% for Tongil and 120% for Jinheung as judged from the reciprocal hardness scale among textural parameters of cooked rice. When the degrees of gelatinization and retrogradation were determined from enzymic digestion, iodine colorimetric method and textural parameters, Tongil variety showed lower degrees of gelatinization and retrogradation than Jinheung variety did. Tongil variety exhibited a higher gelatinization temperature and lower maximum viscosity and breakdown in the amylograms of the rice powder than Jinheung variety did.

• Journal of Hydrogen and New Energy
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• v.30 no.6
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• pp.567-577
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• 2019

Due to the depletion of fossil fuels and environmental pollution, demand for alternative energy is gradually increasing. Among the various methods, a method to convert biomass into alternative fuel has been proposed. The bio-fuel obtained from biomass through pyrolysis process is called pyrolysis oil (PO) or bio-oil. Because PO is difficult to use directly in conventional engines due to its poor fuel properties, various methods have been proposed to upgrade pyrolysis-oil. The simplest approach is to mix it with conventional fossil fuels. However, due to their different polarity of PO and fossil fuel, direct mixing is impossible. To resolve this problem, emulsification of two fuels with a proper surfactant was proposed, but it costs additional time and cost. Alternatively, the use of alcohol fuels as an organic solvent significantly improve the fuel properties such as fuel stability, calorific value and viscosity. In this study, blends of diesel, n-butanol, and coffee ground pyrolysis oil (CGPO) which is one of the promising PO, was applied to diesel generator. Combustion and emissions characteristics of blended fuels were investigated under the entire load range. Experimental results show that ignition delay is similar to that of diesel at high load. Although, hydrocarbon and carbon monoxide emissions are comparable to diesel, significant reduction of nitrogen oxides and particulate matter emissions were observed.

• International Journal of Fluid Machinery and Systems
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• v.9 no.1
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• pp.66-74
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• 2016

Concerning the numerical simulation of high-speed water jet with intensive cavitation this paper presents a practical compressible mixture flow method by coupling a simplified estimation of bubble cavitation and a compressible mixture flow computation. The mean flow of two-phase mixture is calculated by URANS for compressible fluid. The intensity of cavitation in a local field is evaluated by the volume fraction of gas phase varying with the mean flow, and the effect of cavitation on the flow turbulence is considered by applying a density correction to the evaluation of eddy viscosity. High-speed submerged water jets issuing from a sheathed sharp-edge orifice nozzle are treated when the cavitation number, ${\sigma}=0.1$, and the computation result is compared with experimental data The result reveals that cavitation occurs initially at the entrance of orifice and bubble cloud develops gradually while flowing downstream along the shear layer. Developed bubble cloud breaks up and then sheds downstream periodically near the sheath exit. The pattern of cavitation cloud shedding evaluated by simulation agrees experimental one, and the possibility to capture the unsteadily shedding of cavitation clouds is demonstrated. The decay of core velocity in cavitating jet is delayed greatly compared to that in no-activation jet, and the effect of the nozzle sheath is demonstrated.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.9
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• pp.835-843
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• 2008

We have fabricated the source-drain electrodes for OTFTs by screen printing method and manufactured Ag pastes as conductive paste. To obtain excellent conductivity and screen-printability of Ag pastes, the dispersion characteristics of Ag pastes prepared from two types of acryl resins with different molecular structures and Ag powder treated with caprylic acid, triethanol amine and dodecane thiol as surfactant respectively were investigated. The Ag pastes containing Ag powder treated with dodecane thiol having thiol as anchor group or AA4123 with carboxyl group(COOH) of hydrophilic group as binder resin exhibited excellent dispersity. But, Ag pastes(CA-41, TA-41, DT-41) prepared from AA4123 fabricated the insulating layer since the strong interaction between surface of Ag powder and carboxyl group(COOH) of AA4123 interfered with the formation of conduction path among Ag powders. The viscosity behavior of Ag pastes exhibited shear-thinning flow in the high shear rate range and the pastes with bad dispersion characteristic demonstrated higher shear-thinning index than those with good dispersity due to the weak flocculated network structure. The output curve of OTFT device with a channel length of 107 ${\mu}m$ using screen-printed S-D electrodes from DT-30 showed good saturation behavior and no significant contact resistance. And this device exhibited a saturation mobility of $4.0{\times}10^{-3}$ $cm^2/Vs$, on/off current ratio of about $10^5$ and a threshold voltage of about 0.7 V.

• Analytical Science and Technology
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• v.25 no.2
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• pp.127-132
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• 2012

A test tool for self-leveling and flowing characters of coating materials used to semiconductors and electronic parts, especially for protection of LCD and PDP connectors, was designed, and the test tool was evaluated using polymeric siloxane coating materials which have various viscosities. The test results showed that the designed test tool was effective to measure self-leveling and flowing properties of coating materials. Therefore, considering that the viscosity is not directly correlated with self-leveling and flowing properties, we believe that this test tool will be a very useful tool for measurement instead of classical method using viscosities of coating materials. Particularly, the measurement of self-leveling and flowing properties using the test tool would be expected to be used in the area of selecting suitable protective coating materials for LCD (Liquid Crystal Display), PDP (Plasma Display Panel) and semiconductor connection parts.

• Journal of Astronomy and Space Sciences
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• v.4 no.1
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• pp.11-23
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• 1987

In dward nova we assume the primary star as a white dwarf and the secondary as the late type star which filled Roche lobe. Mass flow from the secondary star leads to the formation of thin accretion disk around the white dwarf. We use the $\alpha$ parameter as viscosity to maintain the disk form and propose that the outburst in dwarf nova cause the step increase of source term. With these assumptions we solve the basic equations of stellar structure using New-Raphson method. We show the physical parameters like temperature, density, pressure, opacity, surface density, height and flux to the radius of disk. Changing the value of $\alpha$, we compare several parameters when mass flow rate is constant with those of when luminosity of disk is brightest. At the same time, we obtain time-dependent variations of luminosity and mass of disk. We propose the suitable range of $\alpha$is 0.15-0.18 to the difference of luminosity. We compare several parameters of disk with those of the normal late type stars which have the same molecular weight of disk. These show the temperature and pressure of disk are similar to those of normal stars but the density of disk is lower. Maybe the outburst in dwarf nova is due to the variation of the $\alpha$ value instead of increment of mass flow from the secondary star.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.3
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• pp.1252-1257
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• 2013

This study was used homomixer as one of the manufacturing method to establish optimal manufacturing condition with magnesium chloride emulsion as coagulant. The more rotational speed of homomixer was fast, the more particle size of magnesium chloride emulsion was minute. The particle size was distributed between 1 and $5{\mu}m$. The more minute particle size of emulsion had an effect on increasing viscosity of emulsion and delay of oil phase separation during storage period, so the quality of magnesium chloride emulsion had correlation with dispersed phase particle size. After all the experiments, when manufacturing magnesium chloride emulsion, it used more than 10,000 rpm of rotational speed of homomixer, it showed the best result as coagulant according to the state of texture and the water separation ratio of soybean curd.

• Polymer(Korea)
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• v.26 no.5
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• pp.680-690
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• 2002

Implantable biodegradable wafers were prepared with pamidronate -loaded poly (L-lactide-co-glycolide) (PLGA, 75 : 25 mole ratio by lactide to glycolide, molecular weight : 20000 and 90000 g/mole) by direct compression method for the sustained release of pamidronate to investigate the possibility for the treatment of bone resorption. Pamidronate-loaded PLGA powders were prepared by means of physical mixing and spray drying with the control of formulation factors and characterized by scanning electron microscope and X-ray diffractometer. The pamidronate-loaded PLGA powders fabricated into wafers by direct compression under the constant pressure and time at room temperature. These wafers were also observed for their structural characteristic, release pattern, and degradation pattern. The release rate of pamidronate increased with increasing their initial loading ratio as well as increasing wafer thickness. The molecular weight of PLGA affects the release pattern : the higher molecular weight of PLGA, the faster release rate. It can be explained that the higher viscosity of high molecular PLGA solution at same concentration tends to aggregate PLGA and pamidronate resulting in unstable pharmaceutical dosage form. This system had advantages in terms of simplicity in design and obviousness of drug release rate and nay be useful as an implantable dosage form for the treatment of aural cholesteatoma.

• Nuclear Engineering and Technology
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• v.48 no.6
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• pp.1396-1403
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• 2016

In this study, fast-curing shielding materials were prepared with a two-component polyurethane matrix and a filler material of PbO through a one-step, laboratory-scale method. With an increase in the filler content, viscosity increased. However, the two components showed a small difference. Curing time decreased as the filler content increased. The minimum tack-free time of 27 s was obtained at a filler content of 70 wt%. Tensile strength and compressive strength initially increased and then decreased as the filler content increased. Even when the filler content reached 60 wt%, mechanical properties were still greater than those of the matrix. Cohesional strength decreased as the filler content increased. However, cohesional strength was still greater than 100 kPa at a filler content of 60 wt%. The ${\gamma}$-ray-shielding properties increased with the increase in the filler content, and composite thickness could be increased to improve the shielding performance when the energy of ${\gamma}$-rays was high. When the filler content was 60 wt%, the composite showed excellent comprehensive properties.