• Nuclear Engineering and Technology
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• v.46 no.6
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• pp.863-868
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• 2014

The evaluation of thermal properties of actinide oxide fuels is a problem of high importance for the development of new generation reactors. In the present study, an expression obtained for n-dimensional Debye functions is used to derive a simple analytical expression for the specific heat capacity of nuclear fuels. To test the validity and reliability of this expression, the analytical expression is applied to $UO_2$, $NpO_2$, $ThO_2$, and $PuO_2$. It is seen that the formula was in agreement with the experimental and theoretical results reported in the literature.

• Journal of the Korean Chemical Society
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• v.29 no.1
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• pp.3-8
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• 1985

Molecular electronegativity (EN) values are calculated employing the density functional definition of EN: the negative of the chemical potential in the density functional theory. Calculations are limited to the use of valence electrons (valence electron approximation). Our formula for the EN is given in terms of Hartree-Fock(HF) orbital energies. Resulting EN values for molecules as well as atoms exhibit a remarkable correlation with other existing scales. For molecules, we have achieved electronegativity equalization principle (Sanderson's principle).

• Journal of the Korean Chemical Society
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• v.14 no.1
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• pp.127-131
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• 1970

The variational approach for the direct evaluation of the energy difference ${\Delta}$E is studied. The method is based on the differential equation corresponding to the integral Hellmann-Feynman formula. The ${\Delta}$E is given by the expectation value of the Hermitian operator which does not involve the 1/$r_{ij}$ term. Because of its variational nature of the method, the coupling problem of the differential equations which are encountered in perturbation treatment does not occur. The method is applied to the evaluation of the electric polarizabilities of the Helium isoelectronic series atoms. The result is in good agreement with the experiment. The method is compared with the recent works of Karplus et al.

• Journal of the Korean Vacuum Society
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• v.5 no.4
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• pp.292-300
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• 1996

The scattering of incident ions and target atoms in the amorphous solid matters are calculated by Monte Carlo simulation method. The experimentally derived universal scattering cross-section of Kalbitzer and Oetzmann is used to describe nuclear scattering. For electronic energy loss, the Lindhard-Scharff and Bethe formula are used. Comparing the ion scattering formulas and ranges with the known results of experiment and other programs, we find our results are good agreement with others.

• Journal of Ocean Engineering and Technology
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• v.18 no.1
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• pp.41-46
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• 2004

This paper describes a study on the tearing damage of a ship's bottom plating, during a grounding. It is widely known that different scaling laws are applied for bodies undergoing simultaneous plastic flow and crack propagation in the deformation of plate tearing. Specifically, the basic scaling law is not followed for the fracture. In this study, in order to verify the problem, plate cutting experiments for geometrically similar models have been performed. From the experimental results, it has been observed that the cutting forces and energy for the larger models are significantly lower than those of the smaller models. A simplified analytical method for the estimation of tearing is proposed, based on the experiments. It has been observed that the results of the present formula are highly correlated with the experiments.

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.4
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• pp.417-424
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• 2007

This paper presents a solution that an analytical model for an induction motor and the formula of regenerative power and instantaneous torque are derived. based on the spiral vector. The torque is controlled linearly through variations of the slip angular velocity, based on the field acceleration method (FAM). And also PWM inverter fed induction motor drives is schemed to be easily a regenerative drive. The voltage source inverter fed induction motor drives that regenerative power occurs with back current type is presented, to easily controlled the feedback power and to proper the adaption of energy shaving drives. The experimental tests verify the performance of the FAM, proving that food behavior of the drive is achieved in the transient and steady state operating condition, and are discussed to save the power that regenerative power is measured at the operating acceleration or deceleration of servo system.

• Bulletin of the Society of Naval Architects of Korea
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• v.19 no.4
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• pp.19-29
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• 1982

Galerkin's finite element method is applied to a two-dimensional heat convection-diffusion problem arising in the hydrodynamic lubrication of thrust bearings used in naval vessels. A parabolized thermal energy equation for the lubricant, and thermal diffusion equations for both bearing pad and the collar are treated together, with proper juncture conditions on the interface boundaries. it has been known that a numerical instability arises when the classical Galerkin's method, which is equivalent to a centered difference approximation, is applied to a parabolic-type partial differential equation. Probably the simplest remedy for this instability is to use a one-sided finite difference formula for the first derivative term in the finite difference method. However, in the present coupled heat convection-diffusion problem in which the governing equation is parabolized in a subdomain(Lubricant), uniformly stable numerical solutions for a wide range of the Peclet number are obtained in the numerical test based on Galerkin's classical finite element method. In the present numerical convergence errors in several error norms are presented in the first model problem. Additional numerical results for a more realistic bearing lubrication problem are presented for a second numerical model.

• Proceeding of EDISON Challenge
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• 2016.03a
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• pp.368-372
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• 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.

• Journal of the Korean Society of Safety
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• v.8 no.2
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• pp.87-93
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• 1993

Many methods to assess hazards caused by the risks increased with the growth of petrochemical industry. The manual of International Atomic Energy Agency which was much more applied to quantitative analysis of the real situation and the CPQRA is introduced to verify the theoretical background of this manual. Than other methods, as a result, we can see that this manual, which is simple to use and requires a little information, shows similar results to those of calculation by numerical formula. Also, the program code of this manual was materialized and if it is possible to obtain adequate parameters to our circumstance, the manual will be quite useful in early risk analysis.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1466-1467
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• 2007

A new parameter W/R for the class I test have been introduced in the IEC 61643-1 published in 2005. One of the possible test impulses which meets the parameters for class I test is the 10/350 [${\mu}s$] waveshape proposed in IEC61312-1. 10/350 [${\mu}s$] waveshape meets parameters for class I test in the IEC 61643-1. The impulse generator for making the 10/350 [${\mu}s$] waveshape is consist of IVG, ICG, crowbar coil and crowbar switch. The electric change Q and the specific energy W/R were measured and calculated using the exclusive use measuring software according to the formula of IEC 611643-1. We verified the correspondence between measured results using impulse generator and recommended parameters by IEC 61643-1.