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Search Results: 1 - 10 of 342777 matches for " Kwang S. Kim "
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Nonstationary theory of magnetic field induced current for molecular spin nanojunction
M. Jouravlev,Kwang S. Kim
Physics , 2009,
Abstract: For the study of molecular spin junctions, we take into account two types of couplings between the molecule and the metal leads: (i) electron transfer that gives rise to net current in the biased junction and (ii) energy transfer between the molecule and the leads. Using a rotating wave approximation in the Heisenberg representation, we derive a set of differential equations for the expectation values of relevant variables: electron and phonon populations and molecular polarization. A magnetic field control method to enhance the charge transfer at spin nanojunctions, which characterizes the molecule feature, is discussed. An approximate analytical solution of the resulting dynamical equation is supported by numerical solution. The magnetic control by charge transfer is described by transient pseudo-fermions of electrons interacting with spins. The rapid adiabatic passage of the energy between the molecule and the leads is taken into account. The current for molecular spin nanojunctions is derived.
Carbon nanotube, graphene, nanowire, and molecule-based electron and spin transport phenomena using the non-equilibrium Green function method at the level of first principles theory
Woo Youn Kim,Kwang S. Kim
Physics , 2007, DOI: 10.1002/jcc.20865
Abstract: Based on density functional theory (DFT), we have developed algorithms and a program code to investigate the electron transport characteristics for a variety of nanometer scaled devices in the presence of an external bias voltage. We employed basis sets comprised of linear combinations of numerical type atomic orbitals and k-point sampling for the realistic modeling of the bulk electrode. The scheme coupled with the matrix version of the non-equilibrium Green function method enables determination of the transmission coefficients at a given energy and voltage in a self-consistent manner, as well as the corresponding current-voltage (I-V) characteristics. This scheme has advantages because it is applicable to large systems, easily transportable to different types of quantum chemistry packages, and extendable to describe time-dependent phenomena or inelastic scatterings. It has been applied to diverse types of practical electronic devices such as carbon nanotubes, graphene nano-ribbons, metallic nanowires, and molecular electronic devices. The quantum conductance phenomena for systems involving quantum point contacts and I-V curves are described for the dithiol-benzene molecule in contact with two Au electrodes using the k-point sampling method.
Uncertainties in Gapped Graphene
Eylee Jung,Kwang S. Kim,DaeKil Park
Physics , 2011,
Abstract: Motivated by graphene-based quantum computer we examine the time-dependence of the position-momentum and position-velocity uncertainties in the monolayer gapped graphene. The effect of the energy gap to the uncertainties is shown to appear via the Compton-like wavelength $\lambda_c$. The uncertainties in the graphene are mainly contributed by two phenomena, spreading and zitterbewegung. While the former determines the uncertainties in the long-range of time, the latter gives the highly oscillation to the uncertainties in the short-range of time. The uncertainties in the graphene are compared with the corresponding values for the usual free Hamiltonian $\hat{H}_{free} = (p_1^2 + p_2^2) / 2 M$. It is shown that the uncertainties can be under control within the quantum mechanical law if one can choose the gap parameter $\lambda_c$ freely.
Monte Carlo estimates of thermal averages and analytic continuation
Sharif D. Kunikeev,Kwang S. Kim
Physics , 2012,
Abstract: The Monte Carlo (MC) estimates of thermal averages are usually functions of system control parameters $\lambda $, such as temperature, volume, interaction couplings, etc. Given the MC average at a set of prescribed control parameters $\lambda_{0}$, the problem of analytic continuation of the MC data to $\lambda $-values in the neighborhood of $\lambda_{0}$ is considered in both classic and quantum domains. The key result is the theorem that links the differential properties of thermal averages to the higher-order cumulants. The theorem and analytic continuation formulas expressed via higher-order cumulants are numerically tested on the classical Lennard-Jones cluster system of N=13, 55, and 147 neon particles.
The Aesthetic Turn in Everyday Life in Korea  [PDF]
Kwang Myung Kim
Open Journal of Philosophy (OJPP) , 2013, DOI: 10.4236/ojpp.2013.33054
Abstract: We are living in the transitional age from the rational, analytical, and scientific to the cultural, sensitive, and aesthetic. The aesthetics of everyday life lies at the center of this age. There is no boundary between art and life in contemporary art. Almost all the contents and objects of everyday life became a work of art in the condition of searching for the aesthetic. Since aesthetic theory was shifted from the artist-centered or a work of art-centered to the audience, spectator or beholder-centered, art and everyday life were more closely related to each other. So aesthetic attention or attitude is not specific to art, but pervasive broadly in everyday life. We can embrace the aesthetic concerns in everything we make and use every day. In the long tradition of Korean art, it can be seen that aesthetic consciousness is steeped in day-to-day life as well as the arts. I want to consider the problems of everydayness, Korean aesthetic consciousness in daily life, and contemplation in the aesthetic consciousness. Korean art was characterized by its “lack of refinement” and “nonchalance”. The characteristics of Korean art as the qualities of “technique without technique”, “Planning without plan”, “asymmetrical symmetry” have dominated the everyday consciousness of Korean people as well as Korean art. The extension of aesthetic emotion through experimentation shows us the change of aesthetic consciousness as a new possibility of interpretation. We stand in an urgent situation of the need for a new theory of art. It will be related to the future of aesthetics. For this reason, I think we have to consider the meaning of the aesthetic turn in everyday life.
Problems of Expressiveness in Geoaesthetics  [PDF]
Kwang Myun Kim
Open Journal of Philosophy (OJPP) , 2014, DOI: 10.4236/ojpp.2014.44061
Abstract: Facing in the prospect of geo-environmental activities like volcanic explosions, earthquakes, floods, landslides, subsidence issues, tsunamis, etc., we have to reconsider a sustainable harmony between human beings and nature. Approaching the reality of the changing patterns of the earth’s surface and geological processes geoaesthetically will be helpful in establishing a more desirable relationship between human beings and nature. In this paper the author attempts to consider the meaning of expressiveness in relation to geoaesthetics, and further the author intends to reveal expressiveness through various phenomena of the earth. Expressiveness can evoke emotion as one experiences the aesthetic object. Empathy plays a role in drawing expression from expressiveness. One can find geoaesthetic expression through looking deeply into the expressiveness the earth presents. Earth itself is inanimate, but owing to its plentiful expressiveness it can restore the organic, animate world.
Problems and Prospects of Geoaesthetics  [PDF]
Kwang Myung Kim
Open Journal of Philosophy (OJPP) , 2015, DOI: 10.4236/ojpp.2015.51001
Abstract: Geoaesthetics is the project of making aesthetic sense of nature through geological phenomena. The aesthetic appreciation of nature has recently become urgent because of the serious influence of the natural environment on human beings. The author’s geoaesthetical research is categorized into three problems: art in geology or geology in the arts as the close relationship between art and geology, geological cognition of nature and natural cognition in environmental aesthetics, and the geoaesthetical approach through works of art. Geologic forces and processes have become significant materials for aesthetic sensations. Based on the geoaesthetic perspective, the author explores the ultimate purpose of art as a return to natural order. It seems partly to be related to the ontological problem of art. Here we can feel earthly dynamics, universal calmness, and the contemplative atmosphere simultaneously.
Infection of Human Endothelial Cells by Japanese Encephalitis Virus: Increased Expression and Release of Soluble HLA-E
Shwetank, Onkar S. Date, Kwang S. Kim, Ramanathapuram Manjunath
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0079197
Abstract: Japanese encephalitis virus (JEV) is a single stranded RNA virus that infects the central nervous system leading to acute encephalitis in children. Alterations in brain endothelial cells have been shown to precede the entry of this flavivirus into the brain, but infection of endothelial cells by JEV and their consequences are still unclear. Productive JEV infection was established in human endothelial cells leading to IFN-β and TNF-α production. The MHC genes for HLA-A, -B, -C and HLA-E antigens were upregulated in human brain microvascular endothelial cells, the endothelial-like cell line, ECV 304 and human foreskin fibroblasts upon JEV infection. We also report the release/shedding of soluble HLA-E (sHLA-E) from JEV infected human endothelial cells for the first time. This shedding of sHLA-E was blocked by an inhibitor of matrix metalloproteinases (MMP). In addition, MMP-9, a known mediator of HLA solubilisation was upregulated by JEV. In contrast, human fibroblasts showed only upregulation of cell-surface HLA-E. Addition of UV inactivated JEV-infected cell culture supernatants stimulated shedding of sHLA-E from uninfected ECV cells indicating a role for soluble factors/cytokines in the shedding process. Antibody mediated neutralization of TNF-α as well as IFNAR receptor together not only resulted in inhibition of sHLA-E shedding from uninfected cells, it also inhibited HLA-E and MMP-9 gene expression in JEV-infected cells. Shedding of sHLA-E was also observed with purified TNF-α and IFN-β as well as the dsRNA analog, poly (I:C). Both IFN-β and TNF-α further potentiated the shedding when added together. The role of soluble MHC antigens in JEV infection is hitherto unknown and therefore needs further investigation.
Large Orbital Magnetic Moment and Coulomb Correlation effects in FeBr2
S. J. Youn,B. R. Sahu,Kwang S. Kim
Physics , 2001, DOI: 10.1103/PhysRevB.65.052415
Abstract: We have performed an all-electron fully relativistic density functional calculation to study the magnetic properties of FeBr2. We show for the first time that the correlation effect enhances the contribution from orbital degrees of freedom of $d$ electrons to the total magnetic moment on Fe$^{2+}$ as opposed to common notion of nearly total quenching of the orbital moment on Fe$^{2+}$ site. The insulating nature of the system is correctly predicted when the Hubbard parameter U is included. Energy bands around the gap are very narrow in width and originate from the localized Fe-3$d$ orbitals, which indicates that FeBr2 is a typical example of the Mott insulator.
Poly-Bernoulli numbers and lonesum matrices
Hyun Kwang Kim,Denis S. Krotov,Joon Yop Lee
Mathematics , 2011, DOI: 10.1016/j.laa.2012.11.027
Abstract: A lonesum matrix is a matrix that can be uniquely reconstructed from its row and column sums. Kaneko defined the poly-Bernoulli numbers $B_m^{(n)}$ by a generating function, and Brewbaker computed the number of binary lonesum $m\times n$-matrices and showed that this number coincides with the poly-Bernoulli number $B_m^{(-n)}$. We compute the number of $q$-ary lonesum $m\times n$-matrices, and then provide generalized Kaneko's formulas by using the generating function for the number of $q$-ary lonesum $m\times n$-matrices. In addition, we define two types of $q$-ary lonesum matrices that are composed of strong and weak lonesum matrices, and suggest further researches on lonesum matrices. \
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