• Journal of Magnetics
• /
• 제21권1호
• /
• pp.1-5
• /
• 2016

We investigated the half-metallicity and magnetism at the (001) and (110) surfaces of CsSe in cesium chloride and zinc-blende structures by using the all-electron full-potential linearized augmented plane wave method within the generalized gradient approximation. From the calculated local density of states, we found that all the surfaces preserve the half-metallicity of the bulk structures. The surfaces with a greater polarity have stronger ferromagnetic properties when terminated with Se atoms; the non-polar surfaces do not change their electronic or magnetic properties considerably as compared with the bulk structures.

• 한국생물물리학회:학술대회논문집
• /
• 한국생물물리학회 2003년도 정기총회 및 학술발표회
• /
• pp.79-79
• /
• 2003

SHG (Second harmonic generation) can be used to probe the surface of centrosymmetric particles suspended in bulk isotropic solution, because it is forbidden in centrosymmetric media under the dipole approximation. Using this technique, we can study the transport dynamics of small organic dye molecules across liposome bilayers. Because molecules adsorbed on the outer layer are in opposite direction with that on the inner layer by symmetry, the SH field is proportional to the difference between the number density of dye molecules on both sides of the bilayer, and the time dependence of the SH intensity is related to the time constant of the molecular transportation of dye molecules across liposome bilayers.

• 전기학회논문지P
• /
• 제57권1호
• /
• pp.22-29
• /
• 2008

In this paper, we propose an adaptive color enhancement algorithm. It is used for the flat panel displays (FPDs) such as LCD, PDP, and so on. The proposed algorithm consists of an adaptive linear approximation CDF(Cumulative Density Function) algorithm and an adaptive saturation enhancement algorithm. The one is for contrast enhancement which prevents an image from the distortion by luminance transient of an input image. The other is the algorithm which improves the saturation without the contour artifact and over-saturation, whose problems are generated during the enhancing saturation. In addition, it allows to achieve the high quality image using the saturation enhancement method for a preferred color of original image. Visual test and standard deviation of their histograms have been applied to evaluate the resultant output images of the proposed algorithm.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
• /
• pp.24-27
• /
• 2009

A hybrid model has been developed which adopts a fluid model for electrons and a particle-in-cell (PIC) model for ions. Using the hybrid simulation, the discharge characteristics are investigated with the diagnostics for the electric field and the wall charge profile, density distributions of charged and excited particles, distributions of ultraviolet lights on phosphor, and the visible lights emitted from the PDP cell. Also, energy and angle distributions of the ions at the MgO protective layer are obtained for the analysis of material effect. The comparison of hybrid simulation results with experimental results as well as that with the conventional fluid simulation shows that the new model is more adequate for the simulation of PDP cells.

• 대한기계학회논문집B
• /
• 제33권2호
• /
• pp.101-106
• /
• 2009

The disjoining pressure is an important physical property in modeling the small-scale transport phenomena on thin film. It is a very useful definition in characterizing the non-continuum effects that are not negligible in heat and mass transport of the film thinner than submicro-scales. We present the calculated values of disjoining pressure of He, Kr and Xe thin films absorbed on graphite substrate using Molecular Dynamics Simulation (MD). The disjoining pressure is accurately calculated in the resolution of a molecular scale of the film thickness. The characteristics of the pressure are discussed regarding the molecular nature of the fluid system such as molecular diameter and intermolecular interaction parameters. The MD results are also compared with those based on the continuum approximation of the slab-like density profile and the results on other novel gases in the previous study. The discrepancies of the continuum model with MD results are shown in all three configurations and discussed in the view point of molecular features.

• Journal of Magnetics
• /
• 제16권3호
• /
• pp.201-205
• /
• 2011

We performed total energy and electronic structure calculations for the basic ground state properties of Fe using the conventional generalized gradient approximation (GGA) and screened hybrid functionals as the form of the exchange-correlation functional. To that end, we calculated structural (equilibrium lattice constants, bulk moduli, and cohesive energies) and electronic (magnetic moments and densities of states) properties. Both functional calculations gave the correct ground state, the ferromagnetic bcc phase, in which the structural parameters agreed well with experimental results. However, the description of the cohesive energies and magnetic moments at the ground state exhibited different behavior from each other: the unusually small cohesive energy and large magnetic moment were observed in the screened hybrid functional calculations compared to the GGA calculations. The reason for the difference was examined by analyzing the calculated electronic structures.

• Journal of Magnetics
• /
• 제10권1호
• /
• pp.1-4
• /
• 2005

We investigated the electronic structures and the magnetic properties of Ti-based intermetallic system of CoTi/FeTi/CoTi(110) surface and interface by using the all-electron full potential linearized augmented plane wave (FLAPW) method within the generalized gradient approximation (GGA). The calculated magnetic moments of interface Co and Fe atoms are 0.65 and 0.15 μ/sub B/, respectively. Surface and interface magnetism of CoTi/FeTi/CoTi(110) are discussed using the calculated density of states (DOS) and the spin densities.

• 한국자기학회:학술대회 개요집
• /
• 한국자기학회 2000년도 International Symposium on Magnetics The 2000 Fall Conference
• /
• pp.461-461
• /
• 2000

We have investigated electronic structuresof antiferromagnetic YBaCo_2O_5 using the local spin-density approximation (LSDA) + U method. The charge and orbital ordered insulating ground state is correctly obtained with the strong on-site Coulomb interaction. Co^{2+} and Co^{3+} ions are found to be in the high spin (HS) and intermediate spin (IS) state, respectively. The tetragonal to orthorhombic structural transition is responsible for the ordering phenomena and the spin states of Co ions. The large contribution of the orbital moment to the total magnetic moment indicates that the effect of the spin-orbit coupling is very important in YBaCo_2O_5.

• EDISON SW 활용 경진대회 논문집
• /
• 제5회(2016년)
• /
• pp.368-372
• /
• 2016

In this paper, the physics-based analytical model of transition metal dichalcogenide (TMD)-based double-gate (DG) tunneling field-effect transistors (TFETs) is proposed. The proposed model is derived by using the two-dimensional (2-D) Landauer formula and the Wentzel-Kramers-Brillouin (WKB) approximation. For improving the accuracy, nonlinear and continuous lateral energy band profile is applied to the model. 2-D density of states (DOS) and two-band effective Hamiltonian for TMD materials are also used in order to consider the 2-D nature of TMD-based TFETs. The model is validated by using the tight-binding non-equilibrium Green's function (NEGF)-based quantum transport simulation in the case of monolayer molybdenum disulfide ($MoS_2$)-based TFETs.

• 전기학회논문지
• /
• 제63권10호
• /
• pp.1417-1422
• /
• 2014

Using a parallel plate DC plasma system was prepared. Using this equipment, we investigated the basic discharge characteristics of DC argon plasma in terms of electron density, temperature, voltage and current waveforms and plasma potential. The effects of the electrode gap distance, input voltage, ballast resistance and pressure were measured using electrostatic probe. Plasma simulation using fluid approximation has been performed. External circuit effects was included in the simulation. Measured and calculated current voltage characteristics show similar tendencies.