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

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.652-655
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• 2002

The embedded atom method based on the density functional theory is used for calculating ground state properties of realistic metal systems. In this paper, we had corrected constitutive formulae and parameters on the palladium for the purpose of doing Embedded Atom Method analysis. And then we have computed the properties of the palladium on the fundamental scale of the atomic structure. In result, simulated ground state properties, such as the lattice constant, elastics constants and the sublimation energy, show good agreement with Daw's simulation data and with experimental data.

• Journal of Photoscience
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• 제1권1호
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• pp.15-23
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• 1994

The absorption and fluorescence spectral properties of piroxicam (PRX) in the hydrogenbonding solvents show the most sensitive dependence on the concentration ranging from 8 x 10$^{_5}$ to 2 x10$^{_5}$ M. These are attributed to both the solvent-mediated ground-state intermolecular proton transfer (GSIerPT) leading to formation of the ground state anion and the excited-state intmmolecular proton transfer (ESIraPT). The concentration dependences of the time-resolved emission kinetics at both room temperature and 77 K have also been investigated. It is shown that in the excited state, the ESIraPT of PRX is the dominant process to form a keto tautomer at the high concentration, whereas at the low concentration the excited-state conformational change of the anion is an additional process leading to formation of a zwitterion. The ESI~PT of PRX in the hydrogenbonding solvent is coupled with the ultrafast excited-state solvent reorganization.

• Journal of Photoscience
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• 제12권3호
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• pp.119-122
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• 2005

The photophysical properties of coumarin 6 laser dye have been studied in two solvents; ethanol and acetonitrile using steady-state fluorescence depolarization technique. The experimentally measured reorientation time of coumarin 6 is more or less the same in given solvents at particular temperature. It is found that coumarin 6 rotates slower in acetonitrile than in ethanol especially at higher values of viscosity over temperature. We also measure the ground and excited state dipole moments of coumarin 6 by solvent perturbation method. The results found that excited state dipole moment is greater than ground state dipole moment, which indicates that excited state is more polar than the ground state.

• Geomechanics and Engineering
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• 제33권5호
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• pp.439-451
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• 2023

The construction of shield tunnelling in urban sites is facing serious risks from complex and changeable underground conditions. Construction problems in the sand-clay mixed ground have been more reported in recent decades for its poor control of soil loss in tunnel face, ground settlement and supporting pressure. Since the limitations of observation methods, the conventional physical modelling experiments normally simplify the tunnelling to a plane strain situation whose results are not reliable in mixed ground cases which exhibit more complicated responses. We propose a new method for the study of the mixed ground tunnel through which mixed lays are simulated with transparent soil surrogates exhibiting different mechanical properties. An experimental framework for the transparent soil modelling of the mixed ground tunnel was established incorporated with the self-developed digital image correlation system (PhotoInfor). To understand better the response of face stability, ground deformation, settlement and supporting phenomenon to tunnelling excavation in the sand-clay mixed ground, a series of case studies were carried out comparing the results from cases subjected to different buried depths and mixed phenomenon. The results indicate that the deformation mode, settlement and supporting phenomenon vary with the mixed phenomenon and buried depth. Moreover, a stratigraphic effect exists that the ground movement around mixed face reveals a notable difference.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2007년도 정기 학술대회 논문집
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• pp.199-204
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• 2007

This research aimed at to develop a quantitative assesment technique which uses the measured displacements at the excavated plane during tunnel construction. Tunnel structure has a feature with long extents comparing to the excavated section so that the tunnel safety assesment is more effective by using the measured data of displacements. Tunnel structures show different structural behaviors due to the mechanical characteristics of ground and supports themselves, excavation methods and construction methods of supports, etc. From this point of view, it has very important meanings on the practical aspects that the measured data from the construction cite represent the features of the interaction effects between ground and supports as they are. In this study, both the stress state and the properties of surrounding ground are analyzed by newly incorporated feedback analysis technique which can use the measured displacements directly. Then, the stress state and the properties of ground will be used to obtain the strain distribution of surrounding ground. Finally the tunnel safety can be assessed by comparing the estimated strain through the analysis to the allowable strain of ground quantitatively.

• Journal of Magnetics
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• 제13권4호
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• pp.128-131
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• 2008

We have investigated the electronic structures and magnetic properties of both undoped and doped bcc Ni using the full-potential linearized augmented plane wave (FLAPW) band method. A ferromagnetic ground state is obtained at the equilibrium volume of bcc Ni. When the system is under strain, the nonmagnetic ground state is stabilized. When the Ni is doped with V, the $Ni_{16-x}V_x$ material loses its magnetic properties when x > 2. We have also discussed the possible superconducting properties of $Ni_{16-x}V_x$.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.572-575
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• 1997

The embedded atom method based on density functional theory was developed as a new means for calculating ground state properties of realistic metal system by Murray S. Daw, Stephen M. Foiles and Michael I. Baskes. In the paper, we had corrected constitutive formulae and parameters on the nickel for the purpose of doing Embedded Atom Method analysis. And then we have computed the properties of the nickel on the fundamental scale of the atomic structure. In result, simulated ground state properties, such as the lattice constant, elastics constants and sublimation energy, show good agreement with Daw's simulation data and with experimental data.

• Journal of the Korean Physical Society
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• 제73권11호
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• pp.1612-1618
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• 2018

In this work, the ground-state properties of an interacting electron gas confined in a two-dimensional quantum dot system with the Gaussian potential ${\upsilon}(r)=V_0(1-{\exp}(-r^2/p))$, where $V_0$ and p are confinement parameters, are determined numerically by using the Thomas-Fermi approximation. The shape of the potential is modified by changing the $V_0$ and the p values, and the influence of the confining potential on the system's properties, such as the chemical energy, the density profile, the kinetic energy, the confining energy, etc., is analyzed for both the non-interacting and the interacting cases. The results are compared with those calculated for a harmonic potential, and excellent agreement is obtained in the limit of high p values for both the non-interacting and the interacting cases.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2006년도 동계학술연구발표회 및 자성 스핀트로닉스 국제학술대회
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• pp.2-3
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• 2006