• 전자공학회논문지A
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• 제29A권11호
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• pp.40-48
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• 1992

The wave-kinetic numerical method is used in simulating the irradiance scintillations of optical wave through a two-dimensional random medium containing weak Gaussian fluctuations of the refractive index. The results are compared to existing analytical or numerical results. The wave-kinetic method is a phase-space ray-tracing method for certain key ray trajectories, and the irradiance is calculated by reconstructing the entire beam from these trajectories. The strength of the wave-kinetic method lies in the fact that it can be applied to any type of random media.

• Kyungpook Mathematical Journal
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• 제52권3호
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• pp.327-346
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• 2012

In this paper, we present a simple explicit type numerical method for discretizations in time for solving one dimensional Burgers' equations. The proposed method does not need an iteration process that may be required in most implicit methods and have good convergence and efficiency in computational sense compared to other known numerical methods. For evidences, several numerical demonstrations are also provided.

• Nuclear Engineering and Technology
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• 제52권11호
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• pp.2422-2430
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• 2020

In order to improve calculational efficiency of the CAPP code in the analysis of the hexagonal reactor core, we have tried to implement a refined AFEN method with transverse gradient basis functions and interface flux moments in the hexagonal geometry. The numerical scheme for the refined AFEN method adopted here is the response matrix method that uses the interface partial currents as nodal unknowns instead of the interface fluxes used in the original AFEN method. Since the response matrix method is single-node based, it has good properties such as good calculational efficiency and parallel computing affinity. Because a refined AFEN method equivalent nonlinear FDM response matrix method tried first could not provide a numerically stable solution, a direct formulation of the refined AFEN response matrix were developed. To show the numerical performance of this response matrix method against the original AFEN method, the numerical error analyses were performed for several benchmark problems including the VVER-440 LWR benchmark problem and the MHTGR-350 HTGR benchmark problem. The results showed a more than three times speedup in computing time for the LWR and HTGR benchmark problems due to good convergence and excellent calculational efficiency of the refined AFEN response matrix method.

• 충청수학회지
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• 제6권1호
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• pp.25-43
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• 1993

This paper introduces a numerical method approximating the minimum norm solution to the first kind integral equation Kf = g with its kernel satisfying a certain property, where g belongs to the range space of K. Most of the existing expansion methods suffer from choosing a set of basis functions, whereas this method automatically provides an optimal set of basis functions approximating the minimum norm solution of Kf = g. Perturbation results and numerical experiments are also provided to analyze this method.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.706-711
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• 2003

A numerical method is presented for computing unsteady incompressible two-phase flows with immersed solids. The method is based on a level set technique for capturing the phase interface, which is modified to satisfy a contact angle condition at the solid-fluid interface as well as to achieve mass conservation during the whole calculation procedure. The modified level set method is applied for numerical simulation of bubble deformation in a micro channel with a cylindrical solid block and liquid jet from a micro nozzle.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.828-830
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• 2000

This paper describes BIEM(Boundary Integral Equation Method) for computation of three dimensional electric field distribution and numerical method that an equivalent charge density is unknown variable. After computing numerically the surface charge distribution. the distribution of both potential and electric field are obtained. Finally, this numerical method is applied to the concentric sphere and the coaxial cylindrical model and numerical result is compared to the analytic solution.

• Geomechanics and Engineering
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• 제2권1호
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• pp.45-56
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• 2010

The current study presents a mathematical model and numerical method for free vibration of tapered piles embedded in two-parameter elastic foundations. The method of Discrete Singular Convolution (DSC) is used for numerical simulation. Bernoulli-Euler beam theory is considered. Various numerical applications demonstrate the validity and applicability of the proposed method for free vibration analysis. The results prove that the proposed method is quite easy to implement, accurate and highly efficient for free vibration analysis of tapered beam-columns embedded in Winkler- Pasternak elastic foundations.

• Ocean Systems Engineering
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• 제7권4호
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• pp.399-412
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• 2017

The Gauss-Legendre integral method is applied to numerically evaluate the Green function and its derivatives in finite water depth. In this method, the singular point of the function in the traditional integral equation can be avoided. Moreover, based on the improved Gauss-Laguerre integral method proposed in the previous research, a new methodology is developed through the Gauss-Legendre integral. Using this new methodology, the Green function with the field and source points near the water surface can be obtained, which is less mentioned in the previous research. The accuracy and efficiency of this new method is investigated. The numerical results using a Gauss-Legendre integral method show good agreements with other numerical results of direct calculations and series form in the far field. Furthermore, the cases with the field and source points near the water surface are also considered. Considering the computational efficiency, the method using the Gauss-Legendre integral proposed in this paper could obtain the accurate numerical results of the Green function and its derivatives in finite water depth and can be adopted in the near field.

• 한국항해항만학회지
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• 제44권2호
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• pp.53-64
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• 2020

This paper discusses the hydrodynamic characteristics of a catamaran at low speed. In this study, the Delft 372 catamaran model was selected as the target hull to analyze the hydrodynamic characteristics by using the RANS (Reynold-Averaged Navier-Stokes) numerical method. First, the turbulence study and mesh independent study were conducted to select the appropriate method for numerical calculation. The numerical method for the CFD (Computational Fluid Dynamic) calculation was verified by comparing the hydrodynamic force with that obtained experimentally at high speed condition and it rendered a good agreement. Second, the virtual captive model test for a catamaran at low speed was conducted using the verified method. The drift test with drift angle 0-180 degrees was performed and the resulting hydrodynamic forces were compared with the trends of other ship types. Also, the pure rotating test and yaw rotating test proposed by Takashina, (1986) were conducted. The Fourier coefficients obtained from the measured hydrodynamic force were compared with those of other ship types. Conversely, pure sway test and pure yaw test also were simulated to obtain added mass coefficients. By analyzing these results, the hydrodynamic coefficients of the catamaran at low speed were estimated. Finally, the maneuvering simulation in low speed conditions was performed by using the estimated hydrodynamic coefficients.

• International Journal of Aeronautical and Space Sciences
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• 제3권2호
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• pp.46-58
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• 2002

An inverse method is introduced to construct benchmark problems for the numerical solution of initial value problems. Benchmark problems constructed through this method have a known exact solution, even though analytical solutions are generally not obtainable. The solution is constructed such that it lies near a given approximate numerical solution, and therefore the special case solution can be generated in a versatile and physically meaningful fashion and can serve as a benchmark problem to validate approximate solution methods. A smooth interpolation of the approximate solution is forced to exactly satisfy the differential equation by analytically deriving a small forcing function to absorb all of the errors in the interpolated approximate solution. A multi-variable orthogonal function expansion method and computer symbol manipulation are successfully used for this process. Using this special case exact solution, it is possible to directly investigate the relationship between global errors of a candidate numerical solution process and the associated tuning parameters for a given code and a given problem. Under the assumption that the original differential equation is well-posed with respect to the small perturbations, we thereby obtain valuable information about the optimal choice of the tuning parameters and the achievable accuracy of the numerical solution. Illustrative examples show the utility of this method not only for the ordinary differential equations (ODEs) but for the partial differential equations (PDEs).