• Journal of the Korean Electrochemical Society
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• v.13 no.4
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• pp.223-234
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• 2010

In this review, the theory and applications of the complex capacitance analysis, which can be utilized in analyzing capacitor-like electrochemical systems, were summarized. Theoretically, it was suggested that the imaginary capacitance plots (Cim vs. log f) can provide a simple way to analyze electrochemical characteristics of capacitive systems, without complicated mathematical calculations. The usefulness of the complex capacitance analysis has been demonstrated by applying it to analyze EDLC characteristics of practical porous carbon electrodes, ionic conductivities inside small pores, and ionic resistances in the catalyst layers of polymer electrolyte membrane fuel cells.

• Bulletin of the Korean Chemical Society
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• v.35 no.7
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• pp.2086-2092
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• 2014

Two novel coordination compounds $[Cu_2(pypya)_3(H_2O)_2]{\cdot}Cl{\cdot}(H_2O)_5$ (1) and $\{[Cd(pypya)(ta)_{1/2}]{\cdot}H_2O\}_n$ (2) (Hpypya=2-(3-(pyridin-2-yl)-1H-pyrazol-1-yl)acetic acid, $H_2ta$=terephthalic acid) were synthesized and characterized by single X-ray diffraction. Structure determination reveals that complex 1 and complex 2 crystallize in the triclinic system, with the P-1 space group. The asymmetric unit of 1 contains two Cu(II) ions, and their coordination modes are different. These units of complex 1 are linked together via hydrogen bonds and ${\pi}-{\pi}$ interactions, and the 3D structure of complex 1 was formed. Complex 2, a mononuclear Cd(II) coordination compound, has a 2D structure which was constructed via coordination bonds. TGA and fluorescence spectra analysis of complex 1 and complex 2 have also been studied. In addition, the geometry parameters of complex 1 have been optimized with the B3LYP method of density functional theory (DFT) to explain its coordination behavior. The electronic properties of the complex 1 and ligand Hpypya have been investigated based on the nature bond orbital (NBO) analysis at the B3LYP level of theory. The result verifies that the synergistic effect have occurred in the compound.

• Journal of Korean Society for Atmospheric Environment
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• v.13 no.6
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• pp.427-437
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• 1997

Complex terrain which is rather typical topographic character in Korea would greatly influence the dispersion of air pollutant. In this study, we investigated how the complex terrain in the vicinity of the coal-fired plant affects the air dispersion modeling results by using several US EPA models: SCREEN, CTSCREEN, ISCLT3, ISCST3, and RTDM. Screening analysis was followed by long-term analysis, and the plume movement over the terrain was precisely tracked for selected cases. Screening analysis revealed that the highest concentration of sulfur dioxide occurs at the downwind distance of 1.3 km under the unstable conditions with weak winds. However, this highest level of $SO_2$ could be raised by 4 times even in the presence of a hill of 170 m at a distance of 2 to 3 km. Seasonal and annual average concentrations predicted with the ISCLT3, ISCST3, and RTDM models showed a rapid incrase of $SO_2$ levels in front of the high mountains which are located more than 15 km away fromt the source. The highest concentrations predicted with ISCST3 were significantly higher than those with ISCLT3 and RTDM mainly because ISCST3 chooses simple-terrain model calculations for receptors between stack height and plume height. Although the highest levels under the stable conditions were usually found in the areas beyond 15 km or more, their absolute values were not so high due to enough dispersion effects between the source and the receptors.

• Journal of the Korean Vacuum Society
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• v.5 no.3
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• pp.194-198
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• 1996

Detailed expermental studies of theelectronic structure of the valence and conduction bands of the mixed conductor $\beta$-LiAlindicate that a quasi-gap opens at the Fermi level, and the conduction states are highlylocalized, as opposed to the theoretical band structure calculations that predict predominant metallic behavior. Evidence for complex lithium migration effects involving the surface of Lial , induced by particle (electron or ion) bombardment and mechanical treatment , has been obtained as a byproduct of these experiments.

• Bulletin of the Korean Chemical Society
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• v.24 no.10
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• pp.1521-1524
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• 2003

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.36.1-36
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• 2001

Recently the robot industry has developed quickly. There are robots carrying luggage at factories, the amusement robots (such as the pet-type robot) in the house, and so on. As the ability of computers improve, robot ability also improves, because mary calculations can be done in little time. Consequently robots can perform complex motions by various control methods. The robot in our laboratory was developed in order to assist various works in a hospital. We controlled our robot using PID control method. So this paper is written about PID control.

• Bulletin of the Korean Chemical Society
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• v.13 no.5
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• pp.538-541
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• 1992

An approximate scheme for evaluating total reaction probability is proposed. Semiclassical boundary conditions are imposed well before the asymptotic region in the reactant and product channels to calculate the Green's function and its derivatives. Propagations are confined to a limited regime near the activated complex. Calculations are made for one dimensional Eckart barrier model of H + $H_2$ reaction. Implications of the procedure in multi-dimensional systems are discussed.

• Bulletin of the Korean Chemical Society
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• v.19 no.6
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• pp.628-634
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• 1998

The properties of the n-type impurities nitrogen and phosphorus in diamond have been investigated by means of electronic band structure calculations within the framework of the semiempirical extended Huckel tight-binding method. For diamond with the nitrogen and phosphorus substitutional impurities, calculated density of states shows the impurity level deep in the band gap. This property can be derived from the substantial <111> relaxation of the impurity and nearest-neighbor carbon atoms, which is associated with the population of an antibonding orbital between them. The passivated donor property of the P-vacancy complex which lies deep in the gap is also discussed.

• Bulletin of the Korean Chemical Society
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• v.23 no.1
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• pp.48-52
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• 2002

Using several molecular modeling programs we have performed computer simulations to investigate the complexation behaviors of an ester derivative of p-tert-butylcalix[5]arene (1e) toward a variety of butylammonium ions. Semi-empirical AM1 method was used for calculating the binding energies and the formation enthalpies. MM and CVFF forcefields for molecular mechanics calculations were adapted to express the complexation energies of the host. Molecular dynamics were performed to the calculated complex systems to simulate the ionophoric behavior of the host-guest complexes. The absolute Gibbs free energies of the host (1e) complexed with four kinds of butylammonium ions have been calculated using the Finite Difference Thermodynamic Integration (FDTI) method in Discover. Calculation results show that the trend in complex formation is n-$BuNH_3^+$ > iso-$BuNH_3^+$ >> sec-$BuNH_3^+$ > tert-$BuNH_3^+$, which is in good agreement with the experimental results.

• Bulletin of the Korean Chemical Society
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• v.27 no.7
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• pp.1009-1014
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• 2006

Density functional theory calculations are applied to investigate the intramolecular proton transfer in the tautomers of thymine radical cation and its hydrated complexes with one water molecule. The optimized structures and energies for 6 tautomers and 6 transition states of thymine radical cation are calculated at the B3LYP/6-311++G(d,p) level. It is predicted that the order of relative stability for the keto and enol tautomers of thymine radical cation is the same with that of the neutral thymine tautomers, though the enol tautomers are more stabilized with respect to the di-keto form in the radical cation than in the neutral state. A new channel of proton transfer from >C5-$CH_{3}$ of thymine is found to open and have the lowest energy barrier of other proton transfer processes in thymine radical cation. The roles of hydration are also investigated with thymine-water 1 : 1 complex ions. The presence of water significantly lowers the barrier of the proton transfer, which clearly shows the assisting role of hydration even with one water molecule