• Journal of the Korean Chemical Society
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• v.57 no.3
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• pp.370-376
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• 2013

A back propagation artificial neural network model with one hidden layer is established to correlate the liquid-liquid equilibrium data of hydrocarbon-water systems. The model has four inputs and two outputs. The network is systematically trained with 48 data points in the range of 283.15 to 405.37K. Statistical analyses show that the optimised neural network model can yield excellent agreement with experimental data(the average absolute deviations equal to 0.037% and 0.0012% for the correlated mole fractions of hydrocarbon in two coexisting liquid phases respectively). The comparison in terms of average absolute deviation between the correlated mole fractions for each binary system and literature results indicates that the artificial neural network model gives far better results. This study also shows that artificial neural network model could be developed for the phase equilibria for a family of hydrocarbon-water binaries.

• Archives of Pharmacal Research
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• v.10 no.1
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• pp.25-28
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• 1987

(+)-Ketoprofen was obtained form resolution with (S) (+)-2-amino-1-butanol and its absolute configuration was determined to be (S) by chemical correlation with (S) (+)-ethyl hydratropate using Beckmann rearrangement as a key step.

• Bulletin of the Korean Chemical Society
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• v.4 no.1
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• pp.25-28
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• 1983

The effect of internal rotation of methyl group in liquid perdeuterotoluene on nuclear quadrupole relaxation of methyl deuterons is investigated. A model of a spherical diffusor undergoing rotational diffusion is extended to include the extended diffusion of internal rotation. The overall reorientational correlation time in the presence of internal rotation is explicitly given as an analytical function of the angular momentum correlation time. Also, the degree of inertial effect in the internal rotation is evaluated.

• Bulletin of the Korean Chemical Society
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• v.14 no.1
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• pp.110-112
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• 1993

Molecular reorientation of oblate symmetric top molecules in the presence of internal rotation is investigated and an analytic expression for the overall reorientational correlation time is obtained. The overall reorientation of the symmetric top is treated by the anisotropic rotational diffusion and the internal rotation is analyzed by employing a model which describes jumps between several discrete states with different lifetimes. The lifetimes thus obtained can be compared with the internal angular momentum correlation time which appears when the internal rotation is treated by a modified extended rotational diffusion model.

• Bulletin of the Korean Chemical Society
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• v.8 no.5
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• pp.406-408
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• 1987

It has been shown that the distribution of relaxation times, H(ln $\tau$), in semi-logarithmic time scale can easily be calculated numerically from the derivative of the relaxation function in semilogarithmic scale. In that, ln$\tau$, the abscissa, is divided into N different segments of equal size, then H is considered to be a linear function of ln $\tau$within each segment. The technique has been applied to a Williams-Watts function as well as to the relaxation function obtained by photon correlation spectroscopy from atactic polystyrene glass. It has been demonstrated that the relaxation functions can be precisely reproduced from the calculated distribution functions.

• Bulletin of the Korean Chemical Society
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• v.4 no.5
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• pp.228-230
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• 1983

Molecular reorientation of oblate symmetric top molecules with internal rotation is investigated theoretically and an analytic expression for the overall reorientational correlation time in terms of the internal angular momentum correlation time is derived. This expression is quite different from the expression for prolate symmetric top molecules but reduces to the same expression in the spherical top limit. Fast internal rotation is treated by a modified version of the extended rotational diffusion while the bulky symmetric top mainbody is treated by the rotational diffusion model.

• Bulletin of the Korean Chemical Society
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• v.34 no.9
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• pp.2811-2814
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• 2013

• Journal of the Korean Chemical Society
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• v.16 no.1
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• pp.56-58
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• 1972

• Bulletin of the Korean Chemical Society
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• v.32 no.8
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• pp.2805-2808
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• 2011

• Journal of the Korean Chemical Society
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• v.45 no.6
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• pp.603-607
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• 2001