• Journal of Power Electronics
• /
• 제19권6호
• /
• pp.1591-1600
• /
• 2019

In this paper, a practical SPICE model for an IGBT and a PiN diode is proposed based on the Finite Differential Method (FDM). Other than the conventional Fourier model and the Hefner model, the excess carrier distribution can be accurately solved by a fast FDM in the SPICE simulation tool. In order to improve the accuracy of the SPICE model, the Taguchi method is adopted to calibrate the extracted parameters. This paper presents a numerical modelling approach of an IGBT and a PIN diode, which are also verified by SPICE simulations and experiments.

• Progress in Superconductivity
• /
• 제3권2호
• /
• pp.235-240
• /
• 2002

In this paper, we investigated the current limiting characteristic in the magnetic shielding type fault current limiter(MSFCL). The circuit analysis was executed by using finite differential method(FDM). This paper suggests that the current limiting performance can be achieved in two ways (resistive and inductive one), according to design parameter. By comparing current limiting characteristics in two ways and surveying the important parameters which determine the operational way after fault occurs in the design of MSFCL, it is shown that the magnetic shielding type fault current limiter can be operated in either resistive or inductive way.

• Steel and Composite Structures
• /
• 제17권3호
• /
• pp.305-320
• /
• 2014

The lowest critical value of the compressive force acting in the plane of symmetrically laminated quasi-isotropic thin rectangular plates is investigated. The critical buckling loads of plates with different types of lamination and aspect ratios are parametrically calculated. Finite Differences Method (FDM) and Galerkin Method are used to solve the governing differential equation for Classical Laminated Plate Theory (CLPT). The results calculated are compared with those obtained by the software ANSYS employing Finite Elements Method (FEM). The results of Galerkin Method (GM) are closer to FEM results than those of FDM. In this study, the primary aim is to conduct a parametrical performance analysis of proper plates that is typically conducted at preliminary structural design stage of composite vessels. Non-dimensional values of critical buckling loads are also provided for practical use for designers.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2008년도 정기 학술대회
• /
• pp.2-7
• /
• 2008

A highly efficient moving least squares finite difference method (MLS FDM) for heat transfer analysis of composite material with interface. In the MLS FDM, governing differential equations are directly discretized at each node. No grid structure is required in the solution procedure. The discretization of governing equations are done by Taylor expansion based on moving least squares method. A wedge function is designed for the modeling of the derivative jump across the interface. Numerical examples showed that the numerical scheme shows very good computational efficiency together with high aocuracy so that the scheme for heat transfer problem with different heat conductivities was successfully verified.

• 한국초전도학회:학술대회논문집
• /
• 한국초전도학회 2001년도 High Temperature Superconductivity Vol.XI
• /
• pp.71-71
• /
• 2001

• 한국전산구조공학회논문집
• /
• 제20권6호
• /
• pp.779-787
• /
• 2007

본 연구는 계면경계에서 특이성을 갖는 이종재료 열전달문제를 효율적으로 해석할 수 있는 이동최소제곱 유한차분법을 제시한다 이동최소제곱 유한차분법은 격자망(grid)없이 절점만으로 이동최소제곱법을 이용하여 Taylor 다항식을 구성하고 차분식을 만들어 미분방정식을 직접 푼다. 초평면함수 개념에 근거한 쐐기함수를 이동최소제곱 센스(sense)로 근사식에 매입하여 쐐기거동과 미분 점프에 따른 계면경계 특성을 효과적으로 묘사하고 고속으로 미분을 근사하는 이동최소제곱 유한차분법의 강점을 발휘하도록 했다. 서로 다른 열전달계수를 갖는 이종재료 열전도문제 해석을 통해 이동최소제곱 유한차분법이 계면경계문제에서도 뛰어난 계산효율성과 해의 정확성을 확보할 수 있음을 보였다.

• 한국구조물진단유지관리공학회 논문집
• /
• 제9권4호
• /
• pp.159-168
• /
• 2005

본 연구는 다양한 적층 배열을 갖는 비등방성을 보이는 첨단 복합 신소재 판구조물의 유한 차분 비선형 해석을 수행한다. 복잡한 편미분 방정식으로 표현되는 역학문제들을 수치해석 하는 경우 본 연구에서 사용한 유한차분법은 유한요소법에 비하여 체눈 생성 및 수치적분 과정을 피할 수 장점을 갖는다. 유한차분법을 이용한 많은 연구들은 단지 에너지 방법을 사용한 고정 혹은 단순 경계조건에 대하여 수행되었다. 그러나 이러한 접근방법은 자유경계에 대하여 불가피하게 발생하는 가상점 문제를 충분히 만족시킬 수 없다. 그러므로 본 연구에서는 임의의 경계조건을 갖는 비등방성 복합 적층한의 비선형 거동 문제를 보다 효과적으로 해결할 수 있는 유한차분식을 정식화 하였다. 적층 배열 변화를 비롯한 다양한 매개변수에 대하여 본 연구에서 제안한 접근방법을 사용하여 적층판의 복잡한 비선형 거동을 분석하였다.

• 대한조선학회 특별논문집
• /
• 대한조선학회 2006년도 특별논문집
• /
• pp.34-39
• /
• 2006

In rough seas, water breaker of the sea-going ships is subject to high impact loads due to the green water and some ships' water breaker suffers structure damage. So, a substantial research on the structural response caused by green water impact is required. In this paper, the green water flow on bow deck is simulated by FDM(finite differential method). Using the results of green water simulation, impact loads on water breaker are calculated. Calculation results of the 6200TEU container ship's structural response to this green water impact pressure are shown and discussed for two condiered calculation conditions.

• Computers and Concrete
• /
• 제25권6호
• /
• pp.537-549
• /
• 2020

Geometrically nonlinear axisymmetric bending analysis of shear deformable circular plates on a nonlinear three-parameter elastic foundation was made. Plates ranging from "thin" to "moderately thick" were investigated for three types of material: isotropic, transversely isotropic, and orthotropic. The differential equations were discretized by means of the finite difference method (FDM) and the differential quadrature method (DQM). The Newton-Raphson method was applied to find the solution. A parametric investigation using seven unknowns per node was presented. The novelty of the paper is that detailed numerical simulations were made to highlight the combined effects of the material properties and the boundary conditions on (i) the deflection, (ii) the stress resultants, and (iii) the external load. The formulation was verified through comparison studies. It was observed that the results are highly influenced from the boundary conditions, and from the material properties.

• 한국정밀공학회지
• /
• 제22권1호
• /
• pp.89-96
• /
• 2005

This paper is concerned with a balancing motion formulation and control of the ZMP (Zero Moment Point) for a biped-walking robot that has a prismatic balancing weight or a revolute balancing weight. The dynamic stability equation of a walking robot which have a prismatic balancing weight is conditionally linear but a walking robot's stability equation with a revolute balancing weight is nonlinear. For a stable gait, stabilization equations of a biped-walking robot are modeled as non-homogeneous second order differential equations for each balancing weight type, and a trajectory of balancing weight can be directly calculated with the FDM (Finite Difference Method) solution of the linearized differential equation. In this paper, the 3dimensional graphic simulator is developed to get and calculate the desired ZMP and the actual ZMP. The operating program is developed for a real biped-walking robot IWRⅢ. Walking of 4 steps will be simulated and experimented with a real biped-walking robot. This balancing system will be applied to a biped humanoid robot, which consist legs and upper body, as a future work.