• Journal of the Korean Chemical Society
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• v.10 no.1
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• pp.25-31
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• 1966

It is well known that the coloration and structural changes in thermal treatment of polyacrylonitrile are due to the formation of partly hydrogenated naphthylidine-type ring involving the pendant nitrile groups. Any quantitative study of the reaction, in the sense of kinetics and/or statistics, however, has never been reported. This paper presents that, at first, the disappearance of the nitrile groups follows the first order kinetics, which indicates clearly that nitrile groups do not disappear by a long chain reaction-the kinetic chain length is very short. This observation rules out the long intramolecular and intermolecular propagation chain through which most of the nitrile groups disappear. From the evidence that a similar reaction occurs in propylene carbonate solutions without gel formation, one may conclude that the coloration and structural changes are not necessarily intermolecular reaction. Secondly, a finite amount of nitrile groups remains unreacted at the extrem of reaction-not contributed to the formation of naphthylidine-type ring. The concentration of this unreacted nitrile groups is 19∼22% which is good agreement with the statistically calculated value of 19.2%.

• Journal of the Korean Chemical Society
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• v.40 no.3
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• pp.187-195
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• 1996

Ab initio SCF calculations have been carried out for the five conceivable trimers formed between one hydrogen cyanide and two hydrogen fluorides using a basis set of TZ＋P quality. Several ground state properties of these trimeric complexes have been evaluated, and compared with those of isolated monomers and appropriate dimers. Computed equilibrium geometries, stabilization energies, and dipole moments are given in order to suppliment the available experimental data. At this level of approximation, intramolecular bond distances are consistently shorter than experimental ones. However, intermolecular distances upon complex formation, and dipole moments are overestimated compared with experimental ones. HCN$(HF)_2$ trimer appears to be the most favourable among the five kinds of trimer complex, and also more stable than $(HCN)_2HF$. The typical features of the non-additivity of intermolecular interaction are relatively strong in the HCN$(HF)_2$ trimer.

• Bulletin of the Korean Chemical Society
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• v.31 no.4
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• pp.881-886
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• 2010

A novel Schiff base N-(2,4-dinitro-phenyl)-N'-(1-phenyl-ethylidene)-hydrazine has been synthesized and structurally characterized by X-ray single crystal diffraction, elemental analysis, IR spectra and UV-vis spectrum. The crystal belongs to monoclinic with space group P21/n. The molecules are connected via intermolecular O-$H{\cdots}O$ hydrogen bonds into 1D infinite chains. The crystal structure is consolidated by the intramolecular N-$H{\cdots}O$ hydrogen bonds. weak intermolecular C-$H{\cdots}O$ hydrogen bonds link the molecules into intriguing 3D framework. Furthermore, Density functional theory (DFT) calculations of the structure, stabilities, orbital energies, composition characteristics of some frontier molecular orbitals and Mulliken charge distributions of the title compound were performed by means of Gaussian 03W package and taking B3LYP/6-31G(d) basis set. The time-dependent DFT calculations have been employed to calculate the electronic spectrum of the title compound, and the UV-vis spectra has been discussed on this basis. The results show that DFT method at B3LYP/6-31G(d) level can well reproduce the structure of the title compound.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2678-2683
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• 2007

The interaction between metal molecules and liquid metal molecules was modeled in the molecular scale and simulated by the molecular dynamics method in order to understand behaviors of the cluster on metallic surface in collision process. Lennard-Jones potential had been used as intermolecular potential, and only attraction 때 d repulsion had been used for the behavior of the cluster on the metal surface. As results, the behavior of the cluster was so much influenced by the cluster of liquid metal temperature and function of molecules forces, such as attraction and repulsion, in the collision progress. These results of simulation will be the foundation for the micro fabrication manufacturing by using spray application technology.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2702-2707
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• 2007

The purpose of this study is to calculate the behavior of molecules for the generation of homogeneous thin-films in the process of spray deposition. The calculation system was composed of a suface molecular region and droplet molecular region. The thin-film was generated when droplet molecules fell to surface molecules. Lennard-Jones potential had been used as intermolecular potential, and only attraction 때 d repulsion had been used for the behavior of the droplet on the solid surface. As results, the behavior of the droplet was so much influenced by the surface temperature in the spray deposition process. High temperature of surface has higher porosity and larger spread area. It was found that simulation results generally agreed well with previous the experimental results. This simulation result will be the foundation for the deposition processes of industry.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.1912-1915
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• 2007

The disjoining pressure is critical in modeling the transport phenomena in small scales. They are very useful in characterizing the non-continuum effects that are not negligible in heat and mass transports in the film of less than submicro-scales. We present he disjoining pressure of thin film absorbed on solid substrate using Molecular Dynamics Simulation (MD). The disjoining pressure with respect to the film thickness is accurately calculated in the resolution of a molecular scale. The characteristics of the pressure are discussed regarding the molecular nature of the fluid system like molecular diameter and intermolecular interaction. Also, the MD results are compared with those based on the macroscopic approximation of the slab-like density profile. Significant discrepancy is observed when the effective film thickness is less than several molecular diameter

• 한국연소학회:학술대회논문집
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• 2004.11a
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• pp.161-166
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• 2004

A study of argon droplet vaporization is conducted using molecular dynamics. Instead of using traditional method such as the Navier-Stokes equation. Molecular dynamics uses Lagrangian frame to describe molecular behavior in a system and uses only momentum and position data of all molecules in the system. So every property is not a hypothetical input but a statistical result calculated from the momentum and position data. This work performed a simulation of the first-order stability for phase transition of a three dementional submicron argon droplet within quiescent environment. Lennard-Jones 12-6 potential function is used as a intermolecular potential function. The molecular configuration is examined while an initially non-sperical droplet is changed into the spherical shape and droplet evaporates or condensates.

• Bulletin of the Korean Chemical Society
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• v.31 no.5
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• pp.1326-1330
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• 2010

Evidences have proved the versatile role of sulfur atom in supramolecular chemistry. $^1$Presence of S atom in the molecule usually results in the specific structural properties of molecules. In the present study, $S{\cdots}arene$, $N{\cdots}arene$, $CH{\cdots}{\pi}$, $CH{\cdots}S$ and $CH{\cdots}N$ type of weak interactions stabilize the conformation and self assembly of symmetrical as well as dissymmetrical molecules.

• Bulletin of the Korean Chemical Society
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• v.31 no.5
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• pp.1172-1176
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• 2010

Regioselective perfluorinated [3+2] cycloadducts and 1,2-adducts have been prepared by 1,3-dipolar cycloaddition between benzaldoxime NH-nitrone and perfluorinated alkene, perfluoro-2-methyl-2-pentene. Although the cycloaddition reaction is carried out at room temperature, the corresponding perfluorinated compounds are effectively produced in a high yield. In particular, the methoxy-substituted adducts (4 and 7a) show the self-assembled structure by intermolecular interactions. These derivatives were characterized by IR, $^1H$ and $^{19}F$ NMR, and the absolute structure of perfluorinated adducts was confirmed by X-ray crystallography.

• Archives of Pharmacal Research
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• v.7 no.2
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• pp.115-120
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• 1984

The crystals of bromhexine-HCl, $C_{14}$ H$_{21}$ N$_{2}$Br$_{2}$Cl, are orthohombic, space group Pca2 with a = 14.598(2)A, b=12.461(3)A, c =9 9.186(1) A and Z = 4. Intensity dat for 967 reflections (Fobs > 6.sigma.(F)) were collected on a Rigaku-Denki automatic four circle diffractometer. The structure was solved by the Patterson and Fourier methods. Refinements were carried out to the final R value of 0.082. The cyclohexane ring has a normal chair form and the benzene ring is planar. There are three independenet hydrogen bounds in the structure. One is an intermolecular hydrogen bond (N-H... Cl) and the others are intramolecular hydrogen bonds (N-H...Br, N$^{+}$-H...Cl$^{[-10]}$ ) Apart from the hydrogen bounding system the molecules are held together in the crystal by van der Waals force.e.