• Journal of applied mathematics & informatics
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• v.17 no.1_2_3
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• pp.73-91
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• 2005

The application of Green's function in calculation of flow characteristics around submerged and floating bodies due to a regular wave is presented. It is assumed that the fluid is homogeneous, inviscid and incompressible, the flow is irrotational and all body motions are small. Two methods based on the boundary integral equation method (BIEM) are applied to solve associated problems. The first is a low order panel method with triangular flat patches and uniform distribution of velocity potential on each panel. The second method is a high order panel method in which the kernels of the integral equations are modified to make it nonsingular and amenable to solution by the Gaussian quadrature formula. The calculations are performed on a submerged sphere and some floating spheroids of different aspect ratios. The excellent level of agreement with the analytical solutions shows that the second method is more accurate and reliable.

• International Journal of Naval Architecture and Ocean Engineering
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• v.6 no.1
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• pp.132-150
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• 2014

In this study, the inertial properties of fully filled liquid in a tank were studied based on the potential theory. The analytic solution was obtained for the rectangular tank, and the numerical solutions using Green's 2nd identity were obtained for other shapes. The inertia of liquid behaves like solid in recti-linear acceleration. But under rotational acceleration, the moment of inertia of liquid becomes small compared to that of solid. The shapes of tank investigated in this study were ellipse, rectangle, hexagon, and octagon with various aspect ratios. The numerical solutions were compared with analytic solution, and an ad hoc semi-analytical approximate formula is proposed herein and this formula gives very good predictions for the moment of inertia of the liquid in a tank of several different geometrical shapes. The results of this study will be useful in analyzing of the motion of LNG/LPG tanker, liquid cargo ship, and damaged ship.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.12
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• pp.3227-3234
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• 1996

This paper proposes a new absorbing boundary condition(ABC) for the FDTD simulation of waveguide problems. It is based on the exact analytic expression for the time domain EM wave propatation in the waveguide. The ABC derived from the expression has a convolution form whose kernel (the discrete Green's function) has a simple, closed form formula. Also, it is applicable to the wide variety of waveguide types with conducting boundaries and complex cross-sectional shapes.

• Water for future
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• v.16 no.3
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• pp.181-185
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• 1983

The problem of hydrodynamic pressure on dams during transient earthquake is treated by considering water as being incompressible. A time dependent Green's function is introduced which allows surface waves. The formula of the hydrodynamic pressure due to horizontal and vertical earthquake is derived which permits quantitative determination of the effect of surface waves. Finally, it is found that surface waves may be ignored when the depth of reservoir is large.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.10a
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• pp.187-191
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• 2003

The motion and time-mean drift force of a 2-D floating BBDB in waves are studied with and without taking account of fluctuating air pressure in the air chamber. It has been found numerically that the drift for a of the BBDB is in the reverse direction of propagation of the incident waves over specific frequency ranges as found by McCormick through his experiment work. The drift force is calculated by Pinkster's near-field method. Since Maruo's formula method for the drift force is always positive, Maruo's formula is only approximate and should be replaced by the correct near-field method.

• Water for future
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• v.26 no.1
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• pp.71-79
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• 1993

Nonlinear characteristics of air pressure variation and wave transformation of a fixed air-chamber structure are discussed theoretically and experimentally. Two analytical methods(method I and II) based on the perturbation method and Green's formula are employed in order to evaluate nonlinearities by the submerged and semi-submerged air-chamber structure. Moreover, an air compression model is newly developed to estimate the dynamic air pressure in the air-chamber inside the structure, assuming the Boyle-Charles's law with adiabatic process in the air pressure variation. Theoretical values of the method I considering evanescent mode waves at an fictious boundary, are in good agreement with those of method II employing the fictious boundary which is not affected by evanescent mode waves. Both theoretical values are shown to agree well with experimental values.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.5 no.3
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• pp.204-211
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• 1993

Boundary element method is applied to simulate nonlinear water waves using Green's identity formula in a numerical wave flume. A system of linear equations is formulated from the governing equation and free surface boundary conditions in order to calculate velocity potential and water surface elevation at each nodal point. The velocity square terms are included in the dynamic free surface boundary condition. The free surface is treated as a moving boundary. the vertical variation of velocity potential being considered in calculating the time derivative of the velocity potential at the free surface. The present method is applied to simulate solitary wave and Stokes 2nd order wave, and shows excellent agreements with their theoretical values.

• Structural Engineering and Mechanics
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• v.25 no.2
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• pp.181-200
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• 2007

A decoupling technique for simulating near-field wave motions in two-phase media is introduced in this paper. First, an equivalent but direct weighted residual method is presented in this paper to solve boundary value problems more explicitly. We applied the Green's theorem for integration by parts on the equivalent integral statement of the field governing equations and then introduced the Neumann conditions directly. Using this method and considering the precision requirement in wave motion simulation, a lumped-mass FEM for two-phase media with clear physical concepts and convenient implementation is derived. Then, considering the innate attenuation character of the wave in two-phase media, an attenuation parameter is introduced into Liao's Multi-Transmitting Formula (MTF) to simulate the attenuating outgoing wave in two-phase media. At last, two numerical experiments are presented and the numerical results are compared with the analytical ones demonstrating that the lumped-mass FEM and the generalized MTF introduced in this paper have good precision.

• 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.

• Economic and Environmental Geology
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• v.19 no.spc
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• pp.121-130
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• 1986

In the Janggun mine, stannite occurs as anhedral grains, up to 500 micrometer in long dimension, closely associated with sphalerite, chalcopyrite, arsenopyrite, pyrrhotite, galena and rhodochrosite in the periphery of the South ore body. In reflected light, stannite is grayish yellow green in color and exhibits moderate bireflectance and strong anisotropism without any intenal reflections. Reflection; Rmax. =29.0, Rmin. =27.8 percent at a wavelength of 560nm, and VHN; 219~244kg/mm at a 50g load. The chemical composition on the average from 35 spot analyses by electron microprobe is, Cu 28.0, Fe 12.7, Zn 2.9, Mn 0.2, Sn 25.8, S 30.3, sum 99.9 (all in weight percent); the corresponding chemical formula as calculated on the basis of total atoms=8 is, Cu 1.88 Fe 0.97 Zn 0.19 Mn 0.02 Sn 0.93 S 4.01, which fulfills approximately the ideal formula of $Cu_2FeSnS_4$. The strongest reflections on the X-ray diffraction patterns are; $3.10{\AA}$ (10) (112), $2.72{\AA}$ (5) (020, 004), $1.922{\AA}$ (5) (024), $1.642{\AA}$ (3) (132), $1.244{\AA}$ (3) (143, 136, 235), $1.111{\AA}$(3) (244), $0.958{\AA}$ (1) (048, 422), the patterns are identical with those of literature. From the textural evidence of the microscopic observation, the mineral is considered to have been formed at the middle stage of hydrothermal lead-zinc-silver mineralization.