• The Journal of Natural Sciences
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• v.8 no.1
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• pp.17-22
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• 1995

Dielectric constant was measured near the consolute point of a binary mixture of water and Poly[bis(methoxyethoxyethoxy)phosphazene], MEEP. Dielectric constant changed incontinously at phase separation temperature plotted against the concentration to abtain coexistence curve. The critical temperatures and the critical concentration were $71^{\circ}C$, 5.5% as determined from the coexistence curve, respectivley. The critical exponent of dielectric constant, $\theta$, was 0.85. The dependence of dielectric constant on frequency is discussed in this report.

• Journal of the Korean Chemical Society
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• v.66 no.4
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• pp.278-283
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• 2022

Using the Kirkwood's method, the free energy of a binary lattice solution consisting of two identical interpenetrating sublattices, such as a simple cubic lattice or a body-centered cubic lattice, was calculated up to the tenth order of the reciprocal of absolute temperature. Using this, liquid-liquid coexistence curves and critical solution temperatures for the binary lattice solutions were calculated to quantitatively investigate the effect of non-random mixing of molecules. And it was shown that the coexistence curve of the simple cubic lattice solution was in good agreement with the Monte-Carlo computer simulation result.

• Macromolecular Research
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• v.14 no.2
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• pp.220-229
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• 2006

Several equations of state for hard-sphere chains with various perturbation terms are reviewed. For each model, three characteristic parameters are required to represent phase equilibria of normal fluids and obtained from thermodynamic properties of pure saturated liquids. The models are then compared with computer simulation data to show the effect of attractive contribution forms employed. Calculated values of vapor-liquid equilibria (VLE) of hydrocarbons that can be reproduced for each model are also compared with experimental results. An additional parameter, ${\zeta}_{KB}$, is required to represent the VLE of pure water, which is ascertained to have a strong influence on the theoretical coexistence curve.

• Proceedings of the KAIS Fall Conference
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• 2011.05a
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• pp.306-309
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• 2011

A lattice model based molecular clusters is presented to improve a classical equation of state(EOS) for volumetric properties in the critical region. The term is based on the two assumptions: (1) The Helmholtz energy is individually divided into classical and long-range density fluctuation contribution (2) All molecules form cluster near the critical region due to long-range density fluctuation. To formulate such molecular cluster, we extended the Veytsman statistics originally developed for the cluster due to hydrogen bonding. The probability function in the statistics is modified to represent the characteristics of long-range density fluctuation vanishing far from critical region. The proposed fluctuation contribution was incorporated into the Sanchez-Lacombe EOS and the combined model with 6 adjustable parameters has been tested against experimental VLE data for pure compounds. The combined model is found to well represent flatten critical isotherm for methane and top of the coexistence curve for the tested components.

• Proceedings of the KAIS Fall Conference
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• 2010.05b
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• pp.961-964
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• 2010

A semi-empirical fluctuation term is presented to improve a classical equation of state (EOS) for volumetric properties in the critical region. The term is based on the two assumptions: (1) The Helmholtz energy is individually divided into classical and long-range density fluctuation contribution (2) All molecules form cluster near the critical region due to long-range density fluctuation. To formulate such molecular cluster, we extended the Veytsman statistics originally developed for the cluster due to hydrogen bonding. The probability function in the statistics is modified to represent the characteristics of long-range density fluctuation vanishing far from critical region. The proposed fluctuation contribution was incorporated into the Sanchez-Lacombe EOS and the combined model with 6 adjustable parameters has been tested against experimental VLE data. The combined model is found to well represent flatten critical isotherm for methane and top of the coexistence curve for the tested components. The prediction results for caloric data are in good agreement with the experimental data.

• Bulletin of the Korean Chemical Society
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• v.17 no.4
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• pp.358-362
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• 1996

The ionic strength dependent binding mode of 9-aminoacridine (9AA), a well-known DNA intercalator, to DNA is studied by flow linear dichroism, circular dichroism, fluorescence techniques and equilibrium dialysis. The DNA-bound 9AA exhibits spectral properties corresponding to the intercalative binding mode disregarding the salt concentrations; the angle between the long-axis transition moment of the 9AA molecule and DNA helix axis is calculated to be about 65°, indicating a significant deviation from the classical intercalation. At low salt concentrations, however, upwards bending curve in Stern-Volmer plot is observed (where 9AA is a fluorophore and DNA a quencher), indicating the coexistence of both static and dynamic quenching mechanisms or the existence of an additional binding site.

• Proceedings of the National Institute of Ecology of the Republic of Korea
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• v.4 no.4
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• pp.159-176
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• 2023

The conservation of the raccoon dog (Nyctereutes procyonoides) in South Korea requires the protection and preservation of natural habitats while additionally ensuring coexistence with human activities. Applying habitat map modeling techniques provides information regarding the distributional patterns of raccoon dogs and assists in the development of future conservation strategies. The purpose of this study is to generate potential habitat distribution maps for the raccoon dog in South Korea using geospatial technology-based models. These models include the frequency ratio (FR) as a bivariate statistical approach, the group method of data handling (GMDH) as a machine learning algorithm, and convolutional neural network (CNN) and long short-term memory (LSTM) as deep learning algorithms. Moreover, the imperialist competitive algorithm (ICA) is used to fine-tune the hyperparameters of the machine learning and deep learning models. Moreover, there are 14 habitat characteristics used for developing the models: elevation, slope, valley depth, topographic wetness index, terrain roughness index, slope height, surface area, slope length and steepness factor (LS factor), normalized difference vegetation index, normalized difference water index, distance to drainage, distance to roads, drainage density, and morphometric features. The accuracy of prediction is evaluated using the area under the receiver operating characteristic curve. The results indicate comparable performances of all models. However, the CNN demonstrates superior capacity for prediction, achieving accuracies of 76.3% and 75.7% for the training and validation processes, respectively. The maps of potential habitat distribution are generated for five different levels of potentiality: very low, low, moderate, high, and very high.

• Journal of the Korean Vacuum Society
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• v.20 no.1
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• pp.35-41
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• 2011

In this study, the interface soaking effect in InAs/GaAs strained-layer superlattice (SLS) on crystalline phase modulation has been analyzed by the x-ray diffraction (XRD) curve. The strain variation induced by As and/or Sb soaking was determined by the separation angle between the substrate peak and the 0th-order superlattice satellite peak in the XRD spectra. Contrated that the As/InAs soaking arises minor GaAs-like interfacial layer, the Sb/GaSb soaking induces InSb-like one. The Fourier-transformed curves of the Pendellosung interference oscillation shows that the optimum soaking times of As/InAs and Sb/GaSb are 2 sec and 12 sec, at which the highest crystallineity has, respectively. An anomalous twin-peak phenomenon that a satellite peak splits into two peaks was observed in the SLS structure co-soaked by As and Sb at InAs${\rightarrow}$GaSb interfaces. We suggest that it may be resulted from coexistence of two kinds crystalline phases of InAsSb and GaAsSb due to intermixing of In${\leftrightarrow}$Ga and Sb${\leftrightarrow}$As.