The Experts below are selected from a list of 1596 Experts worldwide ranked by ideXlab platform
In Seok Kang - One of the best experts on this subject based on the ideXlab platform.
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electrical charging of a conducting water droplet in a dielectric fluid on the electrode surface
Journal of Colloid and Interface Science, 2008Co-Authors: Yongmi Jung, Hyunchang Oh, In Seok KangAbstract:Abstract It has been conceived that a charged droplet driven by Coulombic Force can be used as a droplet-based microreactor. As a basic research for such applications, electrical charging of a conducting water droplet is studied experimentally. The effects of electric field, medium viscosity, and droplet size are investigated. It is found that the amount of electrical charging increases with the droplet size and the electric field. However, the medium viscosity does not have a significant effect in the range of the present study. A scaling law is derived from the experimental results. Unlike the case of a perfect conductor, the estimated amount of electrical charge ( Q est ) of a water droplet is proportional to the 1.59 power of the droplet radius (R) and the 1.33 power of the electric field strength (E). (For a spherical perfect conductor, Q is proportional to R 2 and E.) In order to understand these differences, numerical simulations are performed for the idealized droplets of perfect conductor. Comparison of the numerical and experimental results suggests that the differences are mainly due to incomplete charging of a water droplet resulted from the combined effect of electrochemical reaction at electrode and the relatively low conductivity of water.
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deformation and motion of a charged conducting drop in a dielectric liquid under a nonuniform electric field
Journal of Colloid and Interface Science, 2007Co-Authors: Jungim Kim, Yongmi Jung, In Seok KangAbstract:As a tool for transporting a drop inside another fluid, a charged conducting drop driven by Coulombic Force is considered. Specifically, deformation and motion of a charged conducting drop under nonuniform electric fields are studied using the perturbation method. For simplicity in analysis, the applied electric field is assumed to be expressed as the sum of a uniform field and a linear field and the flow is assumed to be in the Stokes flow range. The deformed drop shape due to electrical stress is computed to the first order of the electrical Weber number (W). Then the electric Force and the hydrodynamic drag are computed to derive the formula of the translation velocity, which is valid up to O(W). Several important results have also been obtained for the effect of drop deformation on the electric and hydrodynamic Forces exerted on the drop.
Kwan Hyoung Kang - One of the best experts on this subject based on the ideXlab platform.
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Force acting on a dielectric particle in a concentration gradient by ionic concentration polarization under an externally applied dc electric field
Journal of Colloid and Interface Science, 2005Co-Authors: Kwan Hyoung KangAbstract:There is a concentration-polarization (CP) Force acting on a particle submerged in an electrolyte solution with a concentration (conductivity) gradient under an externally applied DC electric field. This Force originates from the two mechanisms: (i) gradient of electrohydrodynamic pressure around the particle developed by the Coulombic Force acting on induced free charges by the concentration polarization, and (ii) dielectric Force due to nonuniform electric field induced by the conductivity gradient. A perturbation analysis is performed for the electric field, the concentration field, and the hydrodynamic field, under the assumptions of creeping flow and small concentration gradient. The leading order component of this Force acting on a dielectric spherical particle is obtained by integrating the Maxwell and the hydrodynamic stress tensors. The analytical results are validated by comparing the surface pressure and the skin friction to those of a numerical analysis. The CP Force is proportional to square of the applied electric field, effective for electrically neutral particles, and always directs towards the region of higher ionic concentration. The magnitude of the CP Force is compared to that of the electrophoretic and the conventional dielectrophoretic Forces.
Yongmi Jung - One of the best experts on this subject based on the ideXlab platform.
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electrical charging of a conducting water droplet in a dielectric fluid on the electrode surface
Journal of Colloid and Interface Science, 2008Co-Authors: Yongmi Jung, Hyunchang Oh, In Seok KangAbstract:Abstract It has been conceived that a charged droplet driven by Coulombic Force can be used as a droplet-based microreactor. As a basic research for such applications, electrical charging of a conducting water droplet is studied experimentally. The effects of electric field, medium viscosity, and droplet size are investigated. It is found that the amount of electrical charging increases with the droplet size and the electric field. However, the medium viscosity does not have a significant effect in the range of the present study. A scaling law is derived from the experimental results. Unlike the case of a perfect conductor, the estimated amount of electrical charge ( Q est ) of a water droplet is proportional to the 1.59 power of the droplet radius (R) and the 1.33 power of the electric field strength (E). (For a spherical perfect conductor, Q is proportional to R 2 and E.) In order to understand these differences, numerical simulations are performed for the idealized droplets of perfect conductor. Comparison of the numerical and experimental results suggests that the differences are mainly due to incomplete charging of a water droplet resulted from the combined effect of electrochemical reaction at electrode and the relatively low conductivity of water.
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deformation and motion of a charged conducting drop in a dielectric liquid under a nonuniform electric field
Journal of Colloid and Interface Science, 2007Co-Authors: Jungim Kim, Yongmi Jung, In Seok KangAbstract:As a tool for transporting a drop inside another fluid, a charged conducting drop driven by Coulombic Force is considered. Specifically, deformation and motion of a charged conducting drop under nonuniform electric fields are studied using the perturbation method. For simplicity in analysis, the applied electric field is assumed to be expressed as the sum of a uniform field and a linear field and the flow is assumed to be in the Stokes flow range. The deformed drop shape due to electrical stress is computed to the first order of the electrical Weber number (W). Then the electric Force and the hydrodynamic drag are computed to derive the formula of the translation velocity, which is valid up to O(W). Several important results have also been obtained for the effect of drop deformation on the electric and hydrodynamic Forces exerted on the drop.
Is Kang - One of the best experts on this subject based on the ideXlab platform.
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Deformation and motion of a charged conducting drop in a dielectric liquid under a nonuniform electric field
'Elsevier BV', 2019Co-Authors: Jg Kim, Ym Jung, Is KangAbstract:As a tool for transporting a drop inside another fluid, a charged conducting drop driven by Coulombic Force is considered. Specifically, deformation and motion of a charged conducting drop under nonuniform electric fields are studied using the perturbation method. For simplicity in analysis, the applied electric field is assumed to be expressed as the sum of a uniform field and a linear field and the flow is assumed to be in the Stokes flow range. The deformed drop shape due to electrical stress is computed to the first order of the electrical Weber number (W). Then the electric Force and the hydrodynamic drag are computed to derive the formula of the translation velocity, which is valid up to O(W). Several important results have also been obtained for the effect of drop deformation on the electric and hydrodynamic Forces exerted on the drop. (c) 2007 Elsevier Inc. All rights reserved.X1120sciescopu
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Electrical charging of a conducting water droplet in a dielectric fluid on the electrode surface
'Elsevier BV', 2019Co-Authors: Ym Jung, Is KangAbstract:It has been conceived that a charged droplet driven by Coulombic Force can be used as a droplet-based microreactor. As a basic research for such applications, electrical charging of a conducting water droplet is studied experimentally. The effects of electric field, medium viscosity, and droplet size are investigated. It is found that the amount of electrical charging increases with the droplet size and the electric field. However, the medium viscosity does not have a significant effect in the range of the present study. A scaling law is derived from the experimental results. Unlike the case of a perfect conductor, the estimated amount of electrical charge (Q(est)) of a water droplet is proportional to the 1.59 power of the droplet radius (R) and the 1.33 power of the electric field strength (E). (For a spherical perfect conductor, Q is proportional to R-2 and E.) In order to understand these differences, numerical simulations are performed for the idealized droplets of perfect conductor. Comparison of the numerical and experimental results suggests that the differences are mainly due to incomplete charging of a water droplet resulted from the combined effect of electrochemical reaction at electrode and the relatively low conductivity of water. (C) 2008 Elsevier Inc. All rights reserved.X1158sciescopu
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Application of electrokinetic instability for enhanced mixing in various micro-T-channel geometries
'AIP Publishing', 2018Co-Authors: Park J, Sm Shin, Ky Huh, Is KangAbstract:We present simple effective micromixer designs utilizing electrokinetic instability (EKI) with downstream cavity structures in a micro-T channel. The amount of free charge increases at each corner of the cavities where inhomogeneous flow stream meets the electric field curved along the concentration gradient. The resulting Coulombic Force enhances the instability and leads to a repetitive evolutionary flow pattern from one cavity to the next, yielding a higher mixing efficiency. The mixing efficiency is found to increase by about 15% for the channel with herringbone-shape cavities as compared with the straight channel. (c) 2005 American Institute of Physics.X111921sciescopu
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Electric charge-mediated coalescence of water droplets for biochemical microreactors
'AIP Publishing', 2018Co-Authors: Ym Jung, Is KangAbstract:This work proposes the use of charged droplets driven by the Coulombic Force as solution-phase reaction chambers for biological microreactions. A droplet can be charged near an electrode under dc voltage by direct contact to the electrode. This process is called electrical charging of droplet (ECOD). This charged droplet can then be transported rapidly between electrodes following the arc of an electric field line by exploiting electrostatic Force. As on-demand electrocoalescence, both alkalization of phenolphthalein and bioluminescence reaction of luciferase in the presence of adenosine triphosphate are studied to test the feasibility of the biochemical microreactors using ECOD. Two oppositely charged droplets are merged to have a color change immediately after microchemical reaction. The applicability of an ECOD-driven droplet to measurement of glucose concentration is also tested. The glucose concentration is measured using a colorimetric enzyme-kinetic method based on Trinder's reaction [J. Clin. Pathol. 22, 158 (1969)]. The color change in the merged droplet is detected with an absorbance measurement system consisting of a photodiode and a light emitting diode. (C) 2010 American Institute of Physics. [doi:10.1063/1.3427356]X111611sciescopu
Ritsuko Watanabe - One of the best experts on this subject based on the ideXlab platform.
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dynamic behavior of secondary electrons in liquid water at the earliest stage upon irradiation implications for dna damage localization mechanism
Journal of Physical Chemistry A, 2016Co-Authors: Akinari Yokoya, Masatoshi Ukai, Kentaro Fujii, Ritsuko WatanabeAbstract:To clarify the formation of radiation damage in DNA, the dynamic behavior of low-energy secondary electrons produced by ionizing radiation in water was studied by using a dynamic Monte Carlo code that considers the Coulombic Force between electrons and their parent cations. The calculated time evolution of the mean energy, total track length, and mean traveling distance of the electrons indicated that the prehydration of the electrons occurs competitively with thermalization on a time scale of hundreds of femtoseconds. The decelerating electrons are gradually attracted to their parent cations by Coulombic Force within hundreds of femtoseconds, and finally about 12.6% electrons are distributed within 2 nm of the cations. The collision fraction for ionization and electronic excitation within 1 nm of the cation was estimated to be about 40%. If these electrons are decelerated in a living cell, they may cause highly localized lesions around a cation in a DNA molecule through additional dissociative electron t...
