• Korean Chemical Engineering Research
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• v.56 no.5
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• pp.625-630
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• 2018

The electrostatic interactions were investigated between the zirconia and the 11-Mercaptoundecylphosphoric-acid layer formed on gold surfaces for their complex structures. For the investigation, the atomic force microscope was used to measure the surface forces between the surfaces as a function of the salt concentration and pH value. The forces were analyzed with the Derjaguin-Landau-Verwey-Overbeek theory to estimate the potential and charge density of the surfaces for each condition. The concentration dependence of the surface properties, found from the measurement at pH 4 and 8, was consistent with the prediction from the law of mass action. The pH dependence was explained with the ionizable groups on the surface. It was found that the 11-Mercaptoundecylphosphoric-acid layer had higher values for the surface charge densities and potentials than the zirconia surfaces at pH 4 and 8, which may be attributed to the ionized-functional-groups of the layer.

• Journal of the Semiconductor & Display Technology
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• v.22 no.3
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• pp.14-20
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• 2023

The electrostatic chuck is a technology that uses electroadhesion to attach objects and is widely used in semiconductor and display processes. This research conducted Maxwell by varying parameters to examine the distribution and variations of chucking force in a bipolar-type ESC. The parameters that were changed include the material properties of the dielectric layer and attachment substrate, applied voltage to the electrode, and the gap and width between the electrodes. The analysis results showed that as the relative permittivity of the dielectric layer and substrate increased, the chucking force also increased, with the relative permittivity of the substrate having a greater impact on the chucking force. And increasing the applied voltage led to an increase in both the chucking force and its rate of change. Lastly, as the gap between the electrodes increased, the chucking force rapidly decreased until a certain distance, after which the decrease became less significant. On the contrary, increasing the electrode width resulted in a rapid increase in the chucking force until a certain width, beyond which the increase became less pronounced, eventually converging to a chucking force of 1700 Pa. This paper is expected to have high potential for the development and research of ESC for OLED deposition.

• Journal of the Korean Chemical Society
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• v.56 no.2
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• pp.195-200
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• 2012

In this study we present a new approach for computing the partial atomic charge derived from the wavefunctions of molecules. This charge, which we call the "y_charge", was calculated by taking into account the energy level and orbital populations in each molecular orbital (MO). The charge calculations were performed in the software, which was developed by us, developed using the C# programming language. Partial atomic charges cannot be calculated directly from quantum mechanics. According to a partitioning function, the electron density of constituent molecular atoms depends on the electrostatic attraction field of the nucleus. Taking into account the Boltzmann population of each MO as a function of its energy and temperature we obtain a formula of partial charges.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.456-458
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• 2004

We proposed a novel triode-type carbon nanotube field emitter arrays in which extracted gate is surrounded by CNT emitters. We carried out 3-dimensional numerical calculations of electrostatic potential for the proposed CNT-FEAs using the finite element method and compared the results with those obtained from the structure of conventional CNT-FEAs. It was found that the proposed structure could reduce the turn-on voltage for electron emission and improve beam focusing.

• 한국전기화학회:학술대회논문집
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• 2005.07a
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• pp.329-334
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• 2005

In order to find out rational design and synthetic strategies toward efficient hydrogen storage materials, we performed quantum mechanical calculations on a series of the Metal-Organic Frameworks (MOFs) containing functionalized organic linkers. Based on the shape of frontier orbitals and the electrostatic potential map of various MOFs from density functional theory calculations, it was found that the delocalization of electron and asymmetric polarization of the organic linker play an important role in the hydrogen storage capacity of Metal-Organic Frameworks. The prediction of the modeling study could be supported by the hydrogen adsorption experiments using MOF-5 and amine substituted MOF-5, which showed more enhanced hydrogen storage capacity of amine substituted MOF-5 compared with that of MOF-5.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.410-415
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• 2004

Molecular dynamics simulations of nanoimprint lithography in which a stamp with patterns is pressed onto amorphous poly-(methylmethacrylate) (PMMA) surface are performed to study the deformation of polymer. Force fields including bond, angle, torsion, inversion, van der Waals and electrostatic potential are used to describe the intermolecular and intramolecular force of PMMA molecules and stamp. Periodic boundary condition is used in horizontal direction and $Nos\acute{e}$-Hoover thermostat is used to control the system temperature. As the simulation results, the adhesion forces between stamp and polymer are calculated and the mechanism of deformation are investigated. The effects of the adhesion force and friction force on the polymer deformation are also studied to analyze the pattern transfer in nanoimprint lithography. The mechanism of polymer deformation is investigated by means of inspecting the indentation process, molecular configurational properties, and molecular configurational energies.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.04c
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• pp.62-66
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• 2008

Spacecrafts such as most of commercial satellites that are operating in the geostationary orbit can be subjected to intense irradiation by charged particles. The surface made of dielectric materials can therefore become probable sites for damaging electrostatic discharges. Thanks to a specially equipped chamber, the spatial environment can be reproduced experimentally in the laboratory. In this paper, the behavior of high energy electrons injected in polymers such as PolyMethylMetaAcrylate (PMMA) and Kapton is studied. Results obtained by surface potential technique, pulse-electro acoustic device and a cell based on the split Faraday cup system are analyzed and discussed.

• Structural Engineering and Mechanics
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• v.62 no.5
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• pp.519-535
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• 2017

In this article, static analysis of a magneto-electro-elastic (MEE) beam subjected to various thermal loading and boundary conditions has been investigated. Influence of pyroeffects (pyroelectric and pyromagnetic) on the direct quantities (displacements and the potentials) of the MEE beam under different boundary conditions is studied. The finite element (FE) formulation of the MEE beam is developed using the total potential energy principle and the constitutive equations of the MEE material taking into account the coupling between elastic, electric, magnetic and thermal properties. Using the Maxwell electrostatic and electromagnetic relations, variation of stresses, displacements, electric and magnetic potentials along the length of the MEE beam are investigated. Effect of volume fractions, aspect ratio and boundary conditions on the direct quantities in thermal environment has been determined. The present investigation may be useful in design and analysis of magnetoelectroelastic smart structures and sensor applications.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.11a
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• pp.365-368
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• 1995

Charge decay, thermally stimulated current (TSC), charging and discharging currents(I) are measured for corona-charged composite insulating materials. In this study, We will make an experiment in charge decay on composite material surface, TSC, polarity effect and the others in order to analysis its mechanism. Especially, Fiber glass Reinforced Plastics(FRP) is the best composite material which has been so far. Therefore, Its worthy of notice to investigate its characteristic. And then some other materials will be focused on. This experiment measured characteristic of charge decay, dependence of discharging-time and other electrostatic characteristics on FRP.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1998.11a
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• pp.97-105
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• 1998

The goal of this study is to investigate the potential application of triboelectrostatic separation process for removing unburned carbon from fly ash. The process utilizes the difference in electrical charging characteristics between the organic material (carbon) and the mineral matter (fly ash). In the present work, dry separation tests have been conducted on Samchunpo fly ash samples using a bench - scale analytic separator. The test variables studied include air rate, feed rate, electric field strength, particle size, charger material and length, etc. The best separation results were obtained at the air rate 501/min, feed rate 15 g/min and voltage 15 ㎸. The fly ash with carbon content below 1 % was obtained with over 65% recovery.