• Bulletin of the Korean Chemical Society
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• v.26 no.3
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• pp.384-392
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• 2005

Solvent effects on the kinetics of bromophenol blue fading have been investigated within a temperature range in binary mixtures of methanol, ethanol, 1-propanol, ethylene glycol and 1,2-propanediol with water of varying solvent compositions up to 40% by weight of organic solvent component. Correlation of logk with reciprocal of the dielectric constant was linear. Finally a mechanism was proposed for the bromophenol blue fading upon SESMORTAC (study of effect of solvent mixture on the one-step reaction rates using the transition state theory and cage effect) model, by means of this model, the fundamental rate constants of the fading reaction in these solvent systems were calculated.

• Journal of the Korean Society of Safety
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• v.7 no.3
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• pp.53-59
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• 1992

A general theory is developed which enables closed-cup flash points of mixtures of flammable and non-flammable liquid to be estimated from a knowledge of a certain properties of flammability diagram by thermodynamic method. The estimated equations is shown the effect of both the flame inhibiting properties of the vapor of the non-flammable component and the relative volatility of that component. The vapor phase flame inhibition effect results in a even greater elevation of flash points than the rotative volatility of that component. Especially in cases of similar vapor phase flame inhibition of the non-flammable component, the rotative volatility is affected greater elevation of flash points(extinguishing effect).

• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.10a
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• pp.33-36
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• 2003

AC and DC conductivity of the MWNT(Multi walled nanotubes)/polyurethane composites were investigated with respect to the various oxidative conditions, where these means acid concentration, treatment temperature, and treatment time. We suppose that the conditions of oxidation of the MWNTS have a certain influence on the degree of functionalization, damages, and dispersion of the MWNT themselves. Futhermore, the electrical properties of the resulting composites strongly depend on the oxidative conditions of MWNTS. The conductivity of the composites produced by using the optimal condition was measured as a function of frequency with volume content of MWNTS. These experimental results were analyzed using percolation theory Electromagnetic interference shielding effectiveness (SE) of the mixtures of polyurethane (PU), optimized MWNTs, and silver (Ag) is measured in the frequency range from 10 MHz to 6 ㎓ by using ASTM D4935-89. The measured SEs of the mixtures could be controlled from about 55 dB to 85 dB with the compositions of Ag/MWNT and compounding methods(C1, C2).

• Solar Energy
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• v.17 no.3
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• pp.23-33
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• 1997

The theory on phase change temperature control and nucleation of PCM was suggested in this research. The crystallization model of PCM was established. And H2O-NaCl mixtures were selected as cold storage materials for agricultural products and thermo-physical properies of the PCM were analyzed with experimental processes including freeze-thaw cycles.

• Fire Science and Engineering
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• v.15 no.3
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• pp.14-20
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• 2001

The flash points are one of the most important fundamental properties used to determine the potential for fire and explosion hazards of flammable substances. A classification of the flash points is important for the safe handling of flammable liquids which constitute the solvent mixtures. Basic to all flash points behavior are vapor pressure and explosive limits(lower explosive limit and upper explosive limit). The flash points of flammable solvent mixtures can be calculated with the appropriate use of the fundamental laws of Raoult, Dalton, Le Chatelier and activity coefficient models. In this study, the reference values of lower flash points were compared with the calculated values by using Raoult's law and MRSM(modified response surface methodology) model. The lower flash points were in agreement with the predicted by Raoult's law and MRSM model. By means of this methodology, it is possible to evaluate reliability of experimental data of the flash points of the flammable mixtures.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.6C
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• pp.377-384
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• 2006

Theoretical and experimental study of the unconfined penetration (UP) test was conducted to suggest a new test method (referred to as IUP, Improved Unconfined Penetration) for determination of the tensile strength of compacted sand-bentonite mixtures. The tensile strength of compacted mixtures can be calculated from limit analysis based on the theory of perfect plasticity. The measurement errors in new test method were reduced by improving the UP device. Preliminary experiment results indicate that the tensile strength increases with increasing the disk size, loading rate and pH level. In addition, the disk diameter with 25.4 mm and the loading rate with 0.5%/min~1%/min are most suitable condition for the IUP test. The reliability of IPU test was verified by through the fact that good agreement between the IUP and conventional split tensile test results is observed.

• Journal of the Korean Wood Science and Technology
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• v.12 no.3
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• pp.3-8
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• 1984

It is shown that Paul and Jones' Rule of Mixtures modified by Smith and Cox's theory can be used for the fiber-reinforced, sulfur-based composites, when the constant for the linear regression equation is given. The computation results, programmed by Hewlett Packard 75C (HP 75C) using math rom pack for the linear regression form, expressed as $E_c=\frac{1}{3}aE_fV_f+bE_mV_m$, turn out to be a=3.27-3.54 b=-2.47~-2.80. This results indicate that the factors such as density of fiber mat and the amount of matrix used have nothing for affecting the numerical value of the constants a and b of the linear regression form. Conclusively this results also show that the Paul and Jones' Rule of Mixtures which has been used for the composites made by randomly-oriented long fiber can also be used for the composites made by short fiber with the same fiber orientation such as wood and lignocellulosic fibers.

• Korean Chemical Engineering Research
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• v.58 no.3
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• pp.498-498
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• 2020

• Communications for Statistical Applications and Methods
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• v.8 no.3
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• pp.867-873
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• 2001

In this paper we propose a family of skew- f distributions. The family is derived by a scale mixtures of skew-normal distributions introduced by Azzalini (1985) and Henze (1986). The salient features of the family are mathematical tractability and strict inclusion of the normal law. Further it includes a shape parameter, to some extent, controls the index of skewness. Necessary theory involved in deriving the family of distributions is provided and main properties of the family are also studied.

• Journal of the Korean Chemical Society
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• v.35 no.6
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• pp.730-736
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• 1991

In terms of the theory of Flory's Equation of State, the generalized condition for each case of partial miscibilities appearing in the polymer solutions or blends is given. And observing the changes of terms for energies and free volumes in ${\Delta}G_{mix}$ with increasing temperature, their effects on the partial miscibilities are generalized, and the effects of other parameters are also generalized.