• Proceedings of the KIEE Conference
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• 2004.04a
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• pp.68-70
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• 2004

This paper deals with comparison of magnetic field distribution in LOA with slotless/slot stator. We derived magnetic field solutions in terms of vector potential and cylinderical coordinates. In particular this paper accounts for slotting effect due to stator slot opening by introducing a 2-D relative permeance function. The results of predictions from the analysis are compared with corresponding finite element analysis.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.719-720
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• 2008

This paper deals with analytical approach for rotor loss prediction of permanent magnet synchronous generator(PMSG). The rotor losses of synchronous generator are induced by the magnets. Since stator of our model is skewed, slotting effect can be negligible for our PM wind turbine generator. In order to calculate eddy current, this paper derives analytical solutions by the magnetic vector potential. Finally this paper compared analytical result with eddy current density obtained from finite element(FE) calculations using phase current harmonics analysis.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.752-753
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• 2008

The analytical expressions for magnetic field distributions considering slotting effects, cogging torque and back-emf considering skew effects are established. On the basis of magnetic field solutions, electrical parameters such as back-emf constant and winding inductance are obtained. The predicted results are validated extensively by non-linear finite element (FE) analyses. In particular, test results such as back-emf, cogging torque, inductance and resistance measurements are given to confirm the analyses. Finally, generating performances are investigated by applying estimated parameters to equivalent circuit (EC) of the permanent magnet generator (PMG) and validated extensively by FE calculations and measurements.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.794-795
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• 2015

This paper deals with back-EMF characteristic comparison of Vertical and Halbach array double-sided linear generator with coreless type. On the basis of a magnetic vector potential and Maxwell's equations, governing equations are obtained, and magnetic modeling is predicting characteristic analysis by using the Fourier series expansion. And then, we obtained magnetic field solutions and calculated resistance, back-EMF constant. The analytical results used by 2-D cylindrical coordinate system. The analytical method used in this paper is confirmed by comparing with finite element analysis results.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.742-743
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• 2015

Magnetic couplings are do not require any mechanical contact with the power transmitted to the secondary side according to the primary side. For this reason, well-suited for isolated systems such as vacuums or high pressure. So, this paper presents the force characteristic analysis of the permanent magnet (PM) linear coupling with vertical magnetized using an analytical magnetic field calculations. Based on the definition of governing equations and magnetic vector potential, we obtained the analytical solutions according to the boundary condition for each of the regions. Also, we derived from the force generated in the permanent magnet surface using the Maxwell stress tensor. The analytical results are proved the validity by comparing to the finite element method (FEM).

• Journal of computational fluids engineering
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• v.3 no.2
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• pp.17-26
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• 1998

The three-dimensional incompressible Navier-Stokes equations have been solved by a node-centered finite volume method with unstructured hybrid grids. The pressure-velocity coupling is handled by the artificial compressibility algorithm and convective fluxes are obtained by Roe's flux difference splitting scheme with linear reconstruction of the solutions. Euler implicit method with Jacobi matrix solver is used for the time-integration. The viscous terms are discretised in a manner to handle any kind of grids such as tetragedra, prisms, pyramids, hexahedra, or mixed-element grid. Inviscid bump flow is solved to check the accuracy of high order convective flux discretisation. And viscous flows around a circular cylinder and a sphere are studied to show the efficiency and accuracy of the solver.

• Journal of Mechanical Science and Technology
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• v.16 no.4
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• pp.522-531
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• 2002

In order to study the thermal-hydraulic behavior of the cable-in-conduit-conductor (CICC), a numerical model has been developed. In the model, the high heat transfer approximation between superconducting strands and supercritical helium is adopted. The strong coupling of heat transfer at the front of normal zone generates a contact discontinuity in temperature and density. In order to obtain the converged numerical solutions, a moving mesh method is used to capture the contact discontinuity in the short front region of the normal zone. The coupled equation is solved using the finite element method with the artificial viscosity term. Details of the numerical implementation are discussed and the validation of the code is performed for comparison of the results with thse of GANDALF and QSAIT.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.7
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• pp.1590-1596
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• 1995

The energy release rates for a dynamically growing crack in orthotropic materials are expressed explicitly in terms of dynamic stress intensity factors. The stress functions suitable for the problem are found and the evaluation of the J-integral for the theoretical singular crack tip fields yields energy release rates. The present results are simpler than the existing ones and can be reduced to the well known solutions in special cases. Examples of extracting stress intensity factors from the finite element solution using the present results are given for the dynamically growing crack problem of orthotropic materials.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.3 s.258
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• pp.313-321
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• 2007

In this work, the prior indentation theory for a bulk material is extended to an indentation theory for evaluation of thin-film material properties. We first select the optimal data acquisition location, where the strain gradient is the least and the effect of friction is negligible. A new numerical approach to the thin-film indentation technique is then proposed by examining the finite element solutions at the optimal point. With this new approach, from the load-depth curve, we obtain the values of Young's modulus, yield strength, strain-hardening exponent. The average errors of those values are less than 3, 5, 8% respectively.

• Water for future
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• v.20 no.3
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• pp.219-228
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• 1987

Shallow water equations were applied to the flow in and through the opening to a coastal bay with different open boundary conditions. The open boundaries, shaped like a semi-circle, have various radii. the open boundaries therefore are defined in terms of radius given by multiple of the opening width, 2B. It was found from numerical experiments that for adequate results proper radius of the boundary is 3B or greater and that for radius greater than 3B the solutions become stable. For the solution of the shallow water equations a typical Galerkin's finite element method was used.