• Journal of the Korean Society of Safety
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• v.16 no.4
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• pp.103-108
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• 2001

Explosive limit is one of the major physical properties used to determine the fire and explosion hazards of the flammable substances. Explosive limits are used to classify flammable liquids according to their relative flammability. Such a classification is important for the safe handling of flammable liquids which constitute the solvent mixtures. Explosive limits of all compounds and solvent mixtures can be calculated with the appropriate use of the fundamental laws of Raoult, Dalton, Le Chatelier and activity coefficient models. In this paper, Raoult,s law and van Laar equation(activity coefficient model) are shown to be applicable for the prediction of the explosive limits in the flammable ethylacetate-toluene system. The values calculated by the proposed equations were a good agreement with literature data within a given percent. From a given results, by the use of the proposed equations, it is possible to predict explosive limits of the other flammable mixtures. It is hoped eventually that this method will permit the estimation of the explosive Properties of flammable mixtures with improved accuracy and the broader application for other flammable stances.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.7 no.4
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• pp.589-599
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• 1995

The frictional pressure drop of a capillary tube flow is experimentally investigated for pure refrigerants such as R32, R125, and R134a and refrigerant mixtures such as R32/R134a(30/70 by mass percent), R32/R125(60/40), R125/R134a(30/70), and R32/R125/R134a(23/25/52). The binary interaction parameters for the calculation of viscosities of refrigerant mixtures are found based upon the data in the open literature. Several homogeneous flow models predicting the viscosity of two-phase region are compared to select the best model. Cicchitti's equation is known to be the most adequate for the prediction of the viscosity for refrigerant mixtures, which is used in the analysis of adiabatic capillary flows. A model for the prediction of the frictional pressure drop of single and two-phase flow is developed for refrigerant mixtures in this study. This model may be used to design and analyze the performance of a capillary tube in the refrigerating system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.227-228
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• 2007

Although many studies have been carried out about binary gas mixtures with $SF_6$, few studies were presented about breakdown characteristics of $SF_6/CF_4$ mixtures. At present study the breakdown characteristics of SFJCF4 mixtures in uniform field was performed. The experiments were carried out under AC and standard lightning impulse (SLI) voltages. The sphere-sphere electrode whose gap distance was 1 mm was used in a test chamber. $SF_6/CF_4$ mixtures contained from 0 to 100% $SF_6$ and the experimental gas pressure ranged from 0.1 to 0.4 MPa. The results show that addition of $SF_6$ to $CF_4$ increase AC and SLI breakdown voltages. Under AC voltages the breakdown voltages of each mixture were linearly increased according to the quantity of $SF_6$. However under SLI voltages the breakdown voltages of each mixture were similar.

• Journal of Integrative Natural Science
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• v.14 no.3
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• pp.99-106
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• 2021

A mixture of alcohol and water is commonly used as antifreeze, liquor, and the fundamental solvents for the manufacture of cosmetics, pharmaceuticals, and inks in our daily life. Since various properties of alcohol water mixtures such as density, boiling or melting point, viscosity, and dielectric constant are determined by their mixing ratio, it is very important to know the mixing ratio to predict their properties. One of simple method to find the mixing ratio is measuring the density of the mixtures. However, it is not easy to predict the mixing ratio from the density of the mixtures because the relationship between mixing ratio and density has not been established well. The relationship is dependent on the relative sizes of solute and solvent molecules, and their interactions. Recently, an empirical model to predict the density of glycerol water mixture from their mixing ratio has been introduced. The suggested model is simple but quite accurate for glycerol water mixture. In this article, we investigated the applicability of this model to different alcohol water mixtures. Densities for six different alcohol water mixtures containing various alcohols (e.g., ethylene glycol, 1,3-propane diol, propylene glycol, methanol, ethanol, and 1-propanol) were simulated and compared to experimentally measured ones to investigate the applicability of the model proposed for glycerol water mixtures to other alcohol water mixtures. The model predicted the actual density of all alcohol water mixtures tested in this article with high accuracy at various ratios. This model can probably be used to predict the mixing ratio of other alcohol water mixtures from their densities beyond 6 alcohols tested in this article from their densities.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.1
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• pp.47-54
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• 2006

[ $CO_2$ ] and propane mixtures were chosen as promising alternative refrigerants and their performance potentials were evaluated experimentally in an air-conditioning system. Pure $CO_2$ and 85/15, 75/25 and 60/40 binary blends by the charged mass percentage of $CO_2/propane$ were selected as working fluids. The effect of the inlet temperature of the secondary fluids and degree of superheat on the cooling performance was tested and discussed. The charging amounts of refrigerants were adjusted to make the system show the maximum COP. Comparisons among different refrigerants were carried out on the same compressor speed basis for a given operating condition. In addition, the temperature gliding effect of zeotropic mixtures on the system performance were analyzed based on the drop-in test results.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.03b
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• pp.37-37
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• 2010

In these days $SF_6$ mixtures and alternative gas has been studied because of global warming. so although many studies have been carried out about binary gas mixtures with $SF_6$, few studies were presented about breakdown characteristics of $SF_6/N_2$ mixtures. In this paper, breakdown experiment values and breakdown simulation value are compared. Streamer theory was used for predicting breakdown voltage. For accurate simulation, this simulation apply utilization factor using CST program. AC breakdown experiments in non-uniform field was performed to compare with the breakdown simulation values. But with gap lengths increasing, the breakdown voltage is saturated. So simulation need surface roughness factor.

• Journal of the Korean Chemical Society
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• v.15 no.2
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• pp.95-105
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• 1971

The apparent molal volumes ${\phi}_v$ of a series of homologous tetraalkylammonium chlorides, $Me_4NCl, Et_4NCl, Pr_4NCl,\;and\;Bu_4NCl$, in a series of isopropanol-water mixtures have been determined at $30^{\circ}C$ from precision density measurements using pycnometers. The values of ${\phi}_v$ extrapolated to infinite dilution give partial molal volumes $\={V}^{\circ}$s which are almost additive for successive homologues and enable one to determine the absolute individual ionic partial molal volumes. The experimental results are discussed in terrns of the varying size and surface charge of the ions and the structure of the binary solvent mixtures. The results indicate that at 0.1 mole fraction isopropanol the maximum structuredness of water causes a minimum in the tetraalkylammonium-cation partial molal volumes, while at 0.2 mole fraction the solvent structure is such that the free volumes is a minimum and the electrostrictive effect of chloride ion is a maximum.

• Bulletin of the Korean Chemical Society
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• v.18 no.9
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• pp.1017-1021
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• 1997

Solvolyses of p-methoxyphenyl chloroformate in water, D2O, CH3OD, 50% D2O-CH3OD, and in aqueous binary mixtures of acetone, ethanol and methanol are investigated at 25.0 ℃. Product selectivities are reported at 25 ℃ for a wide range of ethanol-water and methanol-water solvent compositions. The Grunwald-Winstein plots of first-order rate constants for p-methoxyphenyl chloroformate with YCl (based on 1-adamantyl chloride) show marked dispersions into three separate curves for the three aqueous mixtures with a small m value and a rate maximum for aqueous alcohol solvents. Third-order rate constants, kww, kaw, kwa and kaa were calculated from the observed kww and kaa values together with kaw and kwa calculated from the intercept and slope of the plot of 1/S vs. [alcohol]/[water]. The calculated rate constants, kcalc and mol % of ester agree satisfactorily with those of the observed rate constants, kobs and mol % of ester, supporting the stoichiometric solvation effect analysis. The kinetic solvent isotope effects determined in water and methanol are consistent with the proposed mechanism of the general base catalyzed carbonyl addition-elimination.

• Bulletin of the Korean Chemical Society
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• v.11 no.6
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• pp.508-511
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• 1990

The simple binary mixtures of pure phospholipids such as DPPC:DSPC and DPPC:DPPA were investigated with differential scanning calorimeter. The thermotropic properties of DPPC and DSPC mixtures did not deviate much from the ideal curves that was obtained on varying either the temperature or the relative proportions of phospholipids. This means that the two phospholipids are completely miscible in the liquid and solid phase. But the thermotropic properties of DPPC and DPPA mixture deviated much from the ideal phase diagram. It resulted from the repulsion between the head groups of acidic phospholipids. Heat capacity suggested by Harden McConell was calculated. The larger $C_p$ was, the sharper the endothermic peak became.

• Journal of the Korean Society of Industry Convergence
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• v.8 no.1
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• pp.37-45
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• 2005

Adsorption equilibrium data of pure solvent vapors (n-Hexane, Toluene, MEK) as well as their binary mixtures on activated carbon (sorbonorit $B_4$) were experimentally determined in the range of 293.2~323.2 K and beyond saturated vapor pressure corresponding to experimental temperature. Langmuir, Freundlich, LRC, W-VSM, FH-VSM were estimated for the predication of single component as well as binary mixtuer systems. The isosteric heat of adsorption at infinite dilution of pure n-hexane, toluene, MEK on activated carbon were 45.18, 25.85, 34.62 Kcal/mol, respectively, also, n-hexane-toluene binary adsorption of activated carbon formed an azeotrope at 293.2 K and total pressure 5.1~10.3 mmHg.