• Tribology and Lubricants
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• v.7 no.1
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• pp.55-60
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• 1991

The emulsion lubrication is expected to get the effects of cooling and lubrication in metal cutting. The purpose of this research was to investigate the lubrication characteristics of the emulsion in a region of the elastohydrodynamic lubrication by experiments using o/w type emulsion lubrication. With the line contact frictional experiment apparatus which is the model of a rolling mechanism, friction coefficient, and oil film thickness were measured. By analyzing these experimental data with the variables of emulsion concentration, load, and rolling velocity, the following results are obtained. Emulsion viscosity $\eta$ for the concentration and pressure can be calculated by the following equation $\eta=\eta_o e^{\alphap}\cdot e^{\beta \phi}$. Where $\beta = (-3.7242+\phi)/\phi, 5%\leq \phi \leq 15%$.

• Tribology and Lubricants
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• v.3 no.1
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• pp.26-30
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• 1987

The effects of high viscosity polybutene lubricant on the asperity contacts between a flat washer and a ball were tested using three balls/two flat washers rotational apparatus. The asperity contacts were dependent on the ratio of EHD flim thickness (h) and surface roughness($\sigma$). The viscosity-pressure coefficient of lubricant gave a significant effect on the film thickness and thereby on h/$\sigma$ ratio.

• Bulletin of the Korean Chemical Society
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• v.35 no.12
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• pp.3527-3531
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• 2014

In this paper, we report thermodynamic and transport properties (diffusion coefficient, viscosity, and thermal conductivity) of diatomic gases ($H_2$, $N_2$, $O_2$, and $Cl_2$) at 273.15 K and 1.00 atm by performing molecular dynamics simulations using Lennard-Jones intermolecular potential and modified Green-Kubo formulas. The results of self-diffusion coefficients of diatomic gases obtained from velocity auto-correlation functions by Green-Kubo relation are in good agreement with those obtained from mean square displacements by Einstein relation. While the results for viscosities of diatomic gases obtained from stress auto-correlation functions underestimate the experimental results, those for thermal conductivities obtained from heat flux auto-correlation functions overestimate the experimental data except $H_2$.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.4
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• pp.479-484
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• 2003

In this paper, film thickness and temperature distribution are measured in EHL point contact at high slip ratios. Infrared temperature mapping with two band pass fillers. proposed by Ausherman (1976). is used to measure temperature distribution. And the optical interferornetric method with two filters (red and green filters) is used to measure film thickness. Result of experiment showed that temperature rising at film and ball surface occurred very dramatically in Dimple zone. As slip velocity, slip ratio and load increased, size of Dimple and temperature rising became more large In addition, Position and shape of Dimple we changed by slip ratios, and increasing of Dimple size decreased traction coefficient. In short, it is appointed that the Dimple phenomenon be developed by the effect of viscosity wedge.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.12
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• pp.1095-1105
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• 2005

Numerical analysis has been carried out to investigate transient turbulent convective heat transfer in a vertical tube for supercritical water near the thermodynamic critical point. Heat transfer and fluid flow in the tube we strongly coupled due to the large variations of thermodynamic and transport properties such as density, specific heat, and turbulent viscosity. As pressure in the tube approaches to the critical pressure, the properties variation with time becomes larger. Heat transfer coefficient rapidly decreases along the tube near the pseudocritical temperature at the tube wall for $P_R<1.2$. Stanton number variation with time is largely reduced in the region of gas-like phase in comparison with Nusselt number. Turbulent viscosity ratio close to the wall increases near the pseudocritical temperature and it gradually decreases with time.

• Korean Chemical Engineering Research
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• v.47 no.4
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• pp.459-464
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• 2009

Gas-liquid mass transfer characteristics were investigated in pressurized three-phase slurry bubble columns with variation of column diameter. Effects of gas velocity, operating pressure, liquid viscosity, solid content in the slurry phase and column diameter on the gas-liquid volumetric mass transfer coefficient($k_La$) were determined. The effects of operating variables on the mass transfer coefficient tended to change with variation of column diameter. The mass transfer coefficient increased with increasing gas velocity or operating pressure but decreased with increasing column diameter, liquid viscosity or solid concentration in the slurry phase. The increase trend of $k_La$ value with increasing gas velocity and the decrease trend of $k_La$ value with increasing liquid viscosity, tended to decrease gradually with increasing column diameter. However, the effects of operating pressure and solid concentration in the slurry phase on the $k_La$ value did not change considerably with variation of column diameter. The values of $k_La$ were well correlated with operating variables with in this experimental conditions as $k_La=0.02D^{-0.26}U_G^{0.28}P^{0.43}{\mu}_L^{-0.04}S_c^{-0.35}$.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.21 no.1
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• pp.28-34
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• 1985

This paper describes that the characteristic of movement and the performance of the directional system of the liquid magnetic compass analyze and investigate in the kinds of compass and the coefficient of viscosity of the liquid of compass, which the horizontal magnetic field of the geo-magnetic is varied from the equator to the polar region (0.39 gauss-0.03 gauss) by use of apparatus generating artificial magnetic fields. The results are as follows; 1. It is confirmed that the measured values and the calculated values on the characteristic of damping curve by the type of compass and coefficient of viscosity has almost agree with one another. 2. As the horizontal magnetic force geo-magnetic field approaches around the equator (0.39 gauss), the horizontal magnetic field get near the polar region (0.03 gauss), its period is to be longer and the compass card prove not to be more stabilized. 3. The coefficient of viscosity of the liquid in the A, B, C, D and E compasses used in the experiment is estimated 0.03 poises, 0.02 poises, 0.02 poises, 0.015 poises and 0.048 poises respectively by computer simulation.

• Korean Journal of Poultry Science
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• v.43 no.1
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• pp.31-38
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• 2016

Consumers demand fresh and high-quality eggs. Egg quality may be represented by shell color, shell weight, egg weight, shell thickness, shell density, albumen height, yolk color, albumen pH and viscosity. Various factors such as strain, age of hen, storage temperature, humidity, the presence of $CO_2$ and storage time affect egg quality. Therefore, we investigated the effects of storage time and temperature on egg quality to define the freshness of Korean market eggs. A total of 1,800 eggs were used for this experiment and were separated into 45 treatments with 40 eggs in each. The treatments were consisted of 15 storage periods (2 d to 30 d) and 3 storage temperatures ($2^{\circ}C$, $12^{\circ}C$, $25^{\circ}C$). Each egg was weighed and broken, and the height of the thick albumen, Haugh units (HU), egg shell color and yolk color were measured by a QCM+system. We also observed the physiochemical properties of eggs such as yolk pH, albumen pH and albumen viscosity. The egg weight, shell weight, albumen height, HU and albumen viscosity significantly decreased with increasing storage time and temperature. However, the albumen and yolk pH significantly increased with increasing storage period and temperature. The interaction effects between the storage period and temperature were significant for shell weight, shell density, egg weight, albumen height, HU, yolk color, yolk pH, albumen pH and albumen viscosity. In the analysis of the correlation with egg quality, the storage temperature exhibited a higher correlation coefficient than the storage period. In conclusion, storage time and temperature are the major factors affecting egg quality, but the storage temperature is a more sensitive determinant of egg quality deterioration compared with the storage period.

• Korean Journal of Food Science and Technology
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• v.22 no.5
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• pp.533-538
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• 1990

In polysaccharide fermentation with Aureobasidium pullulans, the aeration effects on the production of polysaccharide and the rheological properties of fermentation broth were studied. The increase of the aeration rates from 0.5 to 2.0vvm at 500 rpm yielded the maximum specific production rate of polysaccharide from 0.046 to $0.093 (hr^{-1})$, and the maximum specific growth rate of cells from 0.168 to $0.192 (hr^{-1})$. The viscosity behavior of fermentation broths at the different aeration rates followed the power-law ${\tau}= K({\gamma})^n$. The viscosity attributed by cells was about 10% of the total viscosity of fermentation broth and most of viscosity was attributed by the polysaccharide produced. The relationship between power-law parameters and the concentration of polysaccharide generally satisfied the etㄴrations with the regression coefficient greater than 0.980, $lnK(t)= ln({\tau})_o-n(t)\;ln({\gamma})_o\;and\;K(t)=A P(t)^B$.

• Journal of Life Science
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• v.7 no.4
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• pp.342-346
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• 1997

This experiment was carried out to clarify the effects of gibberellin(GA) aplication and bagging on repeening and quality in 'Delaware' grape berries. Treatments are 4 plots(2X2 factorial experiment); GA, GA+bagging, bagging and control. The clusters were dipped twice in 100 ppm GA with GA treatment : 10 days before and after the full bloom. The results obtained as follows: 1. GA treatment made the seedless grape berry reduced in the fresh weight but it hastened the ripening period about 2 weeks. 2. Total soluble solid(TSS), viscosity and pH value of berry juice increased with maturation. The concentration of TSS and viscosity were higher in GA treatment plot than GA non-treatment. 3. Berry-hardness, titratable acidity and alcohol inslouble solid(AIS) decreased with maturation. Expically berry-hardness and AIS decreased more greatly in GA non-treatment than GA treatment. 4. The concentration of anthocyanin increased with ripening but pectic substance didn't fluctuate nearly. These of anthocyanin and pectin were higher in GA non-treatment plot than GA treatment. 5. By analysis of factorial experiment GA treatment was highly significant with the $^{o}$Brix/Acidity ratio, juice viscosity and AIS, but high negatively, significant with berry-hardness and berry fresh weight. And it was significant with T S S and negatively, titratable acidity. Bagging was significant with $^{o}$Brix/Acidity ratio and AIS content, but negatively, titratable acidity. 6. Qualitative characters were high correlated with the $^{o}$Brix/Acidity ratio in simple correlation but direct effect by the path-coefficient analysis didn't coincide with simple correlation. The direct effect of pH was large and juice viscosity, the next. And that of berry-hardness was negligible but, AIS, small negatively.