• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.471-472
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• 2010

In this study, a new modeling framework for predicting temperature and structural behaviors of structures under fire condition is proposed. The proposed modeling framework including fire simulation, heat transfer and structural analysis is applied to simulate fire tests performed on the steel-concrete composite structures in Cardington, UK, for model validations. Good predictions are shown for spatial-temporal temperatures and deflections of fire-damaged steel-concrete structures.

• Wind and Structures
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• v.26 no.6
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• pp.343-354
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• 2018

A realistic FEM structural model is developed to predict the behavior, load transfer, force distribution and performance of a riverine platform under earthquake and environmental loads. The interaction between the transfer plate and the piles supporting the platform is investigated. Transfer plate structures have the ability to redistribute the loads from the superstructure above to piles group below, to provide safe transits of loads to piles group and thus to the soil, without failure of soil or structural elements. The distribution of piles affects the distribution of stress on both soil and platform. A materially nonlinear earthquake response spectrum analysis was performed on this riverine platform subjected to earthquake and environmental loads. A fixed connection between the piles and the platform is better in the design of the piles and the prospect of piles collapse is low while a hinged connection makes the prospect of damage high because of the larger displacements. A fixed connection between the piles and the platform is the most demanding case in the design of the platform slab (transfer plate) because of the high stress values developed.

• Journal of Microbiology
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• v.39 no.3
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• pp.149-153
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• 2001

The electron transfer reaction is one of the most essential processes of life. Not only does it provide the means of transforming solar and chemical energy into a utilizable form for all living organisms, it also extends into a range of metabolic processes that support the life of a cell. Thus, it is of great interest to understand the physical basis of the rates and reduction potentials of these reactions. To identify the major determinants of reduction potentials in redox proteins, we have chosen the simplest electron transfer protein, rubredoxin, a small (52-54 residue) iron-sulfur protein family, widely distributed in bacteria and archaea. Rubredoxins can be grouped into two classes based on the correlation of their reduction potentials with the identity of residue 44; those with Ala44 (ex: Pyrococcus furiosus) have reduction potentials that are ∼50 mV higher than those with Va144 (ex: Clostridium pasteurianum). Based on the crystal structures of rubredoxins from C. pasteurianum and P. furiosus, we propose the identity of residue 44 alone determines the reduction potential by the orientation of the electric dipole moment of the peptide bond between 43 and 44. Based on 1.5 $\AA$ resolution crystal structures and molecular dynamics simulations of oxidized and reduced rubredoxins from C. pasteurianum, the structural rearrangements upon reduction suggest specific mechanisms by which electron transfer reactions of rubredoxin should be facilitated.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.2
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• pp.367-373
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• 2007

The present study investigates numerically nonequilibrium energy transfer between electrons and phonons in metal thin films irradiated by ultrashort pulse lasers and it also provides the temporal and spatial variations of electron and phonon temperatures using the well-established two-temperature model(TTM) on the basis of the Boltzmann transport equation(BTE). This article predicts the crater shapes in gold film structures, and compares the results by using two-dimensional energy transport equation. From the results, it is found that nonequilibrium energy transfer between electrons and phonons takes place, and the equilibrium time increases with the increase of laser fluence. On the other hand, above threshold fluence the ablation time doesn't change nearly with increasing fluences. Compared with one-dimensional TTM, it also reveals that the temporal distributions of electron and phonon temperatures at the top surface estimated by using two-dimensional TTM have a similar tendency. The results show that two-dimensional TTM can simulate the crater shape of metals during the irradiation of femtosecond pulse lasers and the absorbed energy is propagated to z-direction faster than to r-direction.

• Korean Journal of Materials Research
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• v.12 no.5
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• pp.398-406
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• 2002

VAR process is required to control its various operating parameters. Heat transfer simulation has been accomplished to understand development of solidification micro and macro-structures during VAR process in Ti alloys. Optimum VAR process parameters could be also estimated in this study. It was found that macro-structures were closely related to the shape and depth of liquid pool, and solidification parameters, such as temperature gradient, heat flux, solid fraction. The cooling rates were higher at bottom, top, and center part respectively. As cooling rates increased, the $\alpha$ phase decreased in length, width and fraction. In order to evaluate which parameter affects the result of heat transfer calculation most sensitively, the sensitivities of input parameters to the simulation result were examined. The pool depth and cooling rate showed more sensitive to the temperature of the molten metal, heat transfer coefficient, and liquidus respectively. Also, these thermal properties became more sensitive at higher temperatures.

• Earthquakes and Structures
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• v.13 no.1
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• pp.79-87
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• 2017

Seismic analysis of local site conditions is fundamental for a reliable site seismic hazard assessment. It plays a major role in mitigation of seismic damage potential through the prediction of surface ground motion in terms of amplitude, frequency content and duration. Such analysis requires the determination of the transfer function, which is a simple tool for characterizing a soil profile by estimating its vibration frequencies and its amplification potential. In this study, numerical simulations are carried out and are then combined with a statistical study to allow the characterization of design sites classified by the Algerian Building Seismic Code (RPA99, ver 2003), by average transfer functions. The mean transfer functions are thereafter used to compute RPA99 average site factors. In this regard, coming up seismic fields are simulated based on Power Spectral Density Functions (PSDF) defined at the rock basement. Results are also used to compute average site factor where, actual and synthetic time histories are introduced. In absence of measurement data, it is found that the proposed approach can be used for a better soil characterization.

• Steel and Composite Structures
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• v.49 no.5
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• pp.587-602
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• 2023

This article presents the numerical modelling of transient heat transfer in highly heterogeneous composite materials where the thermal conductivity, specific heat and density are assumed to be directional-dependent. This article uses a coupled finite element-finite difference scheme to perform the transient heat transfer analysis of unidirectional (1D) and multidirectional (2D/3D) functionally graded composite panels. Here, 1D/2D/3D functionally graded structures are subjected to nonuniform heat source and inhomogeneous boundary conditions. Here, the multidirectional functionally graded materials are modelled by varying material properties in individual or in-combination of spatial directions. Here, fully spatial-dependent material properties are evaluated using Voigt's micromechanics scheme via multivariable power-law functions. The weak form is obtained through the Galerkin method and solved further via the element-space and time-step discretisation through the 2D-isoparametric finite element and the implicit backward finite difference schemes, respectively. The present model is verified by comparing it with the previously reported results and the commercially available finite element tool. The numerous illustrations confirm the significance of boundary conditions and material heterogeneity on the transient temperature responses of 1D/2D/3D functionally graded panels.

• Bulletin of the Korean Chemical Society
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• v.27 no.7
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• pp.1009-1014
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• 2006

Density functional theory calculations are applied to investigate the intramolecular proton transfer in the tautomers of thymine radical cation and its hydrated complexes with one water molecule. The optimized structures and energies for 6 tautomers and 6 transition states of thymine radical cation are calculated at the B3LYP/6-311++G(d,p) level. It is predicted that the order of relative stability for the keto and enol tautomers of thymine radical cation is the same with that of the neutral thymine tautomers, though the enol tautomers are more stabilized with respect to the di-keto form in the radical cation than in the neutral state. A new channel of proton transfer from >C5-$CH_{3}$ of thymine is found to open and have the lowest energy barrier of other proton transfer processes in thymine radical cation. The roles of hydration are also investigated with thymine-water 1 : 1 complex ions. The presence of water significantly lowers the barrier of the proton transfer, which clearly shows the assisting role of hydration even with one water molecule

• Journal of Photoscience
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• v.10 no.1
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• pp.105-119
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• 2003

Fullerenes, $C_{60}$ and $C_{70}$, display interesting physicochemical properties in solutions, especially due to their unique chemical structures and their good electron accepting abilities. Solubility of fullerenes in different organic solvents and their unusual solvatochromic behavior, the ability of the fullerenes to form aggregates in solutions, and their electron transfer and charge transfer interactions with variety of electron donors, are the subjects of extensive research activities for more than one decade. Many research groups including ours have contributed substantially in the understanding of the solvatochromism, aggregation behavior, and the photoinduced electron transfer and charge transfer chemistry of fullerenes, in condensed phase. Present article is aimed to summarize the important results reported on the above aspects of fullerenes, subsequent to the earlier report from our group (D.K. Palit and J.P. Mittal, Full. Sci. & Tech. 3, 1995, 643-659).)., 643-659)..

• Journal of Magnetics
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• v.17 no.2
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• pp.115-123
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• 2012

Contactless electrical power transfer through an air gap is a revived technology for supplying energy to many movable applications including Maglev. In this paper, magnetic equivalent circuits and analytical models of contactless electrical power transfer systems are developed and evaluated through experiment. Overall coupling coefficient and overall efficiency are introduced as means for evaluating the systems' performance. Compensating capacitors in primary and secondary sides of the systems improve the overall coupling coefficient and overall efficiency. Using the analytical models, the effects of different parameters and variables such as air gap and load current are analyzed to give a high coupling coefficient and an improved efficiency of power transfer for different compensation structures.