• Bulletin of the Korean Chemical Society
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• v.31 no.12
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• pp.3553-3560
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• 2010

A new hydrazone derivative compound has been synthesized and characterized by IR, $^1H$-NMR, $^{13}C$-NMR and UV-vis. spectroscopy techniques, elemental analysis and single-crystal X-ray diffraction (XRD). The new compound crystallizes in monoclinic space group C2/c. In addition to the crystal structure from X-ray experiment, the molecular geometry, vibrational frequencies and frontier molecular orbitals analysis of the title compound in the ground state have been calculated by using the HF/6-31G(d, p), B3LYP/6-311G(d, p) and B3LYP/6-31G(d, p) methods. The computed vibrational frequencies are used to determine the types of molecular motions associated with each of the observed experimental bands. To determine conformational flexibility, molecular energy profile of (1) was obtained by semi-empirical (AM1) calculation with respect to a selected degree of torsional freedom, which was varied from $-180^{\circ}$ to $+180^{\circ}$ in steps of $10^{\circ}$. Molecular electrostatic potential of the compound was also performed by the theoretical method.

• Bulletin of the Korean Chemical Society
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• v.30 no.11
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• pp.2617-2620
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• 2009

Using Coulomb-Yukawa like correlated interaction potentials of integer and noninteger indices the series expansion formulae in terms of multicenter overlap integrals of three complete orthonormal sets of ${\psi}^{\alpha}$‒exponential type orbitals and linear combination coefficients of molecular orbitals are established for the potential of electrostatic field produced by the charges of molecule, where $\alpha$ = 1, 0, ‒1, ‒2,${\cdots}$. The formulae obtained can be useful for the study of interaction between atomic--molecular systems containing any number of closed and open shells when the ${\psi}^{\alpha}$‒exponential type basis functions and Coulomb-Yukawa like correlated interaction potentials are used in the Hartree-Fock-Roothaan and explicitly correlated approximations. The final results are valid for the arbitrary values of parameters of correlated interaction potentials and orbitals. As an example of application, the calculations have been performed for the potential energy of interaction between electron and molecule $H_2O$ using combined Hartree-Fock-Roothaan equations suggested by the author.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.327-334
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• 2004

Spectroscopic and electrostatic probe measurements were made to examine plasma characteristics with or without a metal plate for a 10-㎾-class direct-current arcjet Heat fluxes into the plate from the plasma were also evaluated with a Nickel slug and thermocouple arrangement. Ammonia and mixtures of nitrogen and hydrogen were used. The NH$_3$ and $N_2$+3H$_2$ plasmas in the nozzle and in the downstream plume without a plate were in thermodynamical nonequilibrium states. As a result, the H-atom electronic excitation temperature and the $N_2$ molecule-rotational excitation temperature intensively decreased downstream in the nozzle although the NH molecule-rotational excitation temperature did not show an axial decrease. Each temperature was kept in a small range in the plume without a plate except for the NH rotational temperature for NH$_3$ gas. On the other hand, as approaching the plate, the thermodynamical nonequilibrium plasma came to be a temperature-equilibrium one because the plasma flow tended to stagnate in front of the plate. The electron temperature had a small radial variation near the plate. Both the electron number density and the heat flux decreased radially outward, and an increase in H$_2$ mole fraction raised them at a constant radial position. In cases with NH$_3$ and $N_2$+3H$_2$ a large number of NH radical with a radially wide distribution was considered to cause a large amount of energy loss, i.e., frozen flow loss, for arcjet thrusters.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2022-2024
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• 2005

Electrical double-layer capacitor (EDLC) is an electrochemical energy storage device in which electric charges only accumulated by a pure electrostatic attraction force are stored on the electrolyte-electrode interface in a form of double layer and separated by the electrolyte. The composite was prepared by mixing nanosize $TiO_2$ and activated carbon through a means of ultrasonic vibration in ethanol solution for 30 min in various mass ratios of $AC:TiO_2$ to form activated carbone-semiconducting oxide composites. Either 1.0 M $LiClO_4/EC-DEC$ or $Et_4NBF_4$/EC-DEC was used as the electrolyte. It was found that with modification of $TiO_2$, the specific capacitance of activated carbon measured at $1mA/cm^2$ was increased from 40 to 50 F/g. This method is unique in comparison the conventional method because it uses semiconducting TiO2 other than electrochemically active materials such as $RuO_2$. The increase in specific capacitance could be attributed to the decrease in electric polarization, caused by the introduction of $RuO_2$.

• Resources Recycling
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• v.16 no.4
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• pp.47-60
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• 2007

Plastic supply and recycling are increasingly becoming matters of social concern. In our country, Extended Producer Responsibility(EPR) system has been adopted in 2003 to expand recycle and reuse of waste resources at producer side, and due to expansion of the EPR system, amount of the mixed plastic waste generation has been drastically increased. Plastic-plastic separation is most fundamental technique to achieve effective plastic recycling. This paper reviews recent developments in plastic-plastic separation techniques and describe future tasks. The mechanisms of each separation which contain gravity separation, electrostatic separation, flotation, and separation of automotive shredder residue are described, and commercial scale and lab-scale results are introduced.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.144.2-144.2
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• 2013

With the synthesis of graphene sheets as large-scale and high quality, it is essentially important to develop suitable graphene patterning process for future industrial applications. Especially, transfer or patterning method of CVD-grown graphene has been studied. We report simple soft lithographic process to develop easily applicable patterning method of large-scale graphene sheets by using chemically functionalized polymer stamp. Also important applications, the prototype capacitors with graphene electrode and commercial polymer dielectrics for the electrostatic-type touch panel are fabricated using the developed soft lithographic patterning and transfer process.

• Structural Engineering and Mechanics
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• v.76 no.4
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• pp.451-463
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• 2020

In this paper, a new semi-analytical solution for estimating the pull-in parameters of electrically actuated functionally graded (FG) nanobeams is proposed. All the bulk and surface material properties of the FG nanoactuator vary continuously in thickness direction according to power law distribution. Here, the modified couple stress theory (MCST) and Gurtin-Murdoch surface elasticity theory (SET) are jointly employed to capture the size effects of the nanoscale beam in the context of Euler-Bernoulli beam theory. According to the MCST and SET and accounting for the mid-plane stretching, axial residual stress, electrostatic actuation, fringing field, and dispersion (Casimir or/and van der Waals) forces, the nonlinear nonclassical equation of motion and boundary conditions are obtained derived using Hamilton principle. The proposed semi-analytical solution is derived by employing Galerkin method in conjunction with the Particle Swarm Optimization (PSO) method. The proposed solution approach is validated with the available literature. The freestanding behavior of nanoactuators is also investigated. A parametric study is conducted to illustrate the effects of different material and geometrical parameters on the pull-in response of cantilever and doubly-clamped FG nanoactuators. This model and proposed solution are helpful especially in mechanical design of micro/nanoactuators made of FGMs.

• Bulletin of the Korean Chemical Society
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• v.19 no.5
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• pp.569-575
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• 1998

Investigation of the structure of the gangliosides has proven to be very important in the understanding of their biological roles. We have determined the tertiary structure of asialoganglioside GM1 $(GA_1)$ using NMR spectroscopy and distance geometry calculations. All of the structures are very similar except the glycosidic torsion angles in the ring IV and ring III linkages. There are two low-energy structures for GA1, G1 and G2. G1 differs from G2 only in the IV-III glycosidic linkages and the orientation of acetamido group in ring III. There is a stable intramolecular hydrogen bond between the third hydroxyl group in ring I and the ring oxygen atom in ring II. Also, there may be a weak hydrogen bond between the second hydroxyl group in ring IV and the acetamido group in ring III. Small coupling constants of $^3J_{IH3,IOH3}\; and\; ^3J_{IVH2,IVOH2}$ support this result. Overall structural features of $(GA_1)$ are very similar to those of $(GM_1)$. It implicates that specificities of the sugar moieties in GM1 are caused not by their tertiary foldings, but mainly by the electrostatic interactions between the polar sialic acid and its receptors. Since it is evident that $(GA_1)$ is more hydrophobic than $(GA_1)$, a receptor with a hydrophobic binding site can recognize the $(GA_1)$ better than $(GA_1)$. Studies on the conformational properties of $(GA_1)$ may lead to a better understanding of the molecular basis of its functions.

• Journal of the Korean Magnetic Resonance Society
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• v.22 no.4
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• pp.139-143
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• 2018

Short antimicrobial peptide, A4W, have been studied by molecular dynamics (MD) simulation in an explicit dodecylphosphocholine (DPC) micelle. Peptide was aligned with DPC micelle and transferred new peptide-micelle coordinates within the same solvent box using specific micelle topology parameters. After initial energy minimization and equilibration, the conformation and orientation of the peptide were analyzed from trajectories obtained from the RMD (restrained molecular dynamics) or the subsequent free MD. Also, the information of solvation in the backbone and the side chain of the peptide, hydrogen bonding, and the properties of the dynamics were obtained. The results showed that the backbone residues of peptide are either solvated using water or in other case, they relate to hydrogen bonding. These properties could be a critical factor against the insertion mode of interaction. Most of the peptide-micelle interactions come from the hydrophobic interaction between the side chains of peptide and the structural interior of micelle system. The interaction of peptide-micelle, electrostatic potential and hydrogen bonding, between the terminal residues of peptide and the headgroups in micelle were observed. These interactions could be effect on the structure and flexibility of the peptide terminus.

• Korean Journal of Metals and Materials
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• v.46 no.2
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• pp.105-110
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• 2008

Process of the hydroxyapatite (HA) formation on bioactive titanium metal prepared by NaOH treatment in a modified-simulated body fluid (mSBF) containing bovine serum albumin (BSA) was investigated by high resolution transmission electron microscope attached with energy dispersive X-ray spectrometer (EDX). The amorphous titanate, which was formed on titanium surface by NaOH treatment, combined with the calcium ions in the liquid to form an amorphous calcium titanite. With increasing of soaking time in the liquid, an amorphous calcium titanite combined with the phosphate ions to form an amorphous calcium phosphate with low Ca/P atomic ratio, and it grows as aggregates of plate (or needle)-like substance on titanium surface. The crystalline apatite layers, which are needle-shaped with the c axis parallel to the long axis, are formed in an amorphous calcium phosphate with further increase in soaking time. The formation of needle-shaped apatite layers can be explained by electrostatic effects and difference of concentration between calcium, phosphate, and albumin ions.