• Progress in Superconductivity and Cryogenics
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• v.16 no.4
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• pp.53-56
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• 2014

A numerical method of magnetic field calculation for the air-core solenoid is presented in this paper. In application of the Biot-Savart law, the magnetic field induced from the source current can be obtained by a double integration ormula. The numerical method named composite Simpson's rule for the integration is applied to the program and the adaptive quadrature method is used to adjust the step size in the calculation according to the precision we need. When the target point is in the solenoid and the intergrand's denominator may be zeroin the process of calculation, the method sill can provide an appropriate result. We have developed a program which calculates the magnetic field with at least 1ppm precision and named it as rzBI() to implement this method. The method has been used in the design of an MRI magnet, and the result show it is very flexible and convenient.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2001.02a
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• pp.172-175
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• 2001

AC loss which is generated in an HTS wire varies with the direction of the external magnetic field. This paper calculates the AC loss in an HTS tape, where effects of the perpendicular direction of the magnetic field are considered. Brandt equation is used to calculate the loss by perpendicular magnetic field. In the calculation, current densities are varied along the variation of the magnitude of the external magnetic field. Results of calculation are compared with those of the conventional method.

• Progress in Superconductivity and Cryogenics
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• v.12 no.1
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• pp.28-31
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• 2010

A magnetic field calculation method for toroidal type winding which has circular section was developed. At first, the equation for magnetic field by single filament coil was extended using numerical integration to estimate the entire interesting region of solenoid, especially winding region itself. And then, the magnetic field by toroidal arrangement of solenoids was computed with a coordinate transformation of vector fields. The superconducting magnet with toroidal arrangement can be made up of several tens of solenoid type double pancake windings for some applications such as superconducting magnetic energy storage system(SMES). In this system, the field calculation on the high-Tc superconducting(HTS) tape itself is very important because the entire system can be reached to a fault by magnetic stress of conductor or the critical current of superconducting tape can be dramatically reduced under its self field condition. To make matters worse, 3-dimensional analysis is indispensable for this type of magnet and the most of commercial programs with finite element method can be taken too much time for analysis and design. In this paper, a magnetic field calculation method for toroidal type winding with circular section was induced.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.6
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• pp.309-315
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• 1999

Coupling loss is generated by the time-varying external magnetic field in the normal matrix of the multi-filamentary HTS tape. This paper calculates the coupling loss in the HTS tape. Analytic calculation of the coupling loss cannot consider the effect of the different shapes and the arrangement of the filaments. Numerical calculation by using finite element method and analytic calculation of the coupling loss have been done in this paper and results of two calculations have been compared. Transverse magnetic field and longitudinal magnetic field were considered as the external field.

• Progress in Superconductivity and Cryogenics
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• v.17 no.2
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• pp.45-49
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• 2015

It has been well known that a toroid is the inevitable shape for a high temperature superconducting (HTS) coil as a component of a large scale superconducting magnetic energy storage system (SMES) because it is the best option to minimize a magnetic field intensity applied perpendicularly to the HTS wires. Even though a perfect toroid coil does not have a perpendicular magnetic field, for a practical toroid coil composed of many HTS pancake coils, some type of perpendicular magnetic field cannot be avoided, which is a major cause of degradation of the HTS wires. In order to suggest an optimum design solution for an HTS SMES system, we need an accurate, fast, and effective calculation for the magnetic field, mechanical stresses, and stored energy. As a calculation method for these criteria, a numerical calculation such as an finite element method (FEM) has usually been adopted. However, a 3-dimensional FEM can involve complicated calculation and can be relatively time consuming, which leads to very inefficient iterations for an optimal design process. In this paper, we suggested an intuitive and effective way to determine the maximum magnetic field intensity in the HTS coil by using an analytic and statistical calculation method. We were able to achieve a remarkable reduction of the calculation time by using this method. The calculation results using this method for sample model coils were compared with those obtained by conventional numerical method to verify the accuracy and availability of this proposed method. After the successful substitution of this calculation method for the proposed design program, a similar method of determining the maximum mechanical stress in the HTS coil will also be studied as a future work.

• Journal of Korea Foundry Society
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• v.20 no.2
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• pp.129-140
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• 2000

This study aims at the phase-field modeling of the phase transformation in graphitization of the cast iron. As the first step, we constructed a phase-field model including the phases with negligible solubility. Under the dilute regular solution approximation, a simplified version of the phase-field model was obtained, which can be used for the phase transformation related with the stoichiometric phases. The results from the numerical calculation of the phase-field model was in good agreement with the exact analytic solution. The compositional shift due to Gibbs-Thomson effect can be reproduced within 0.5% error in the numerical calculation. The interface velocity, whereas, in numerical calculation of phase-field model appeared to be 15% larger than that from the analytic solution. This error is due to the shift of the interface position in phase-field model from the position with ${\phi}=0.5$.

• Nuclear Engineering and Technology
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• v.55 no.9
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• pp.3213-3228
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• 2023

As an important part of the digital reactor, the pin-by-pin wise fine coupling calculation is a research hotspot in the field of nuclear engineering in recent years. It provides more precise and realistic simulation results for reactor design, operation and safety evaluation. CORCA-K a nodal code is redeveloped as a robust pin-by-pin wise neutronics and thermal-hydraulic coupled calculation code for pressurized water reactor (PWR) core. The nodal green's function method (NGFM) is used to solve the three-dimensional space-time neutron dynamics equation, and the single-phase single channel model and one-dimensional heat conduction model are used to solve the fluid field and fuel temperature field. The mesh scale of reactor core simulation is raised from the nodal-wise to the pin-wise. It is verified by two benchmarks: NEACRP 3D PWR and PWR MOX/UO₂. The results show that: 1) the pin-by-pin wise coupling calculation system has good accuracy and can accurately simulate the key parameters in steady-state and transient coupling conditions, which is in good agreement with the reference results; 2) Compared with the nodal-wise coupling calculation, the pin-by-pin wise coupling calculation improves the fuel peak temperature, the range of power distribution is expanded, and the lower limit is reduced more.

• Journal of Electrical Engineering and Technology
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• v.10 no.5
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• pp.2077-2082
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• 2015

Based on Deutsch assumption, a calculation method on the electric field over the ground surface under HVDC transmission lines in the wind is proposed. Analyzing the wind effects on the electric field and the space charge density the existing method based on Deutsch assumption is improved through adding the wind speed to the ion flow field equations. The programming details are illustrated. The calculation results at zero wind speed are compared with available data to validate the code program. Then the ionized fields which resulted from corona of ±800kV HVDC lines are analyzed. Both the electric field and the current density on the ground level are computed under different wind direction and speed. The computation results are in good agreement with measurements. The presented method and code program can be used to rapidly predict and evaluate the wind effects in HVDC transmission engineering.

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2047-2050
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• 1999

This paper presents some of the results of current research on 300 kN Suspension Insulator Design. In this paper, authors first used 2-dimensional field calculation to solve the electric field distribution of an insulator unit and insulator strings, and then 3-dimensional field calculation in order to overcome the shortcomings of 2-dimensional field calculation in which an axis-symmetrical coordinate has been used. And, it was found that the environmental configuration of 300 kN Suspension Insulator String gives great roles to the field distribution of the insulators.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.147-149
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• 1994

In designing high efficiency electrical machines, calculation of iron loss is very important. And it is reported that in the induction motor and in the T-joint of 3 phase transformer, there occurred rotational magnetic field and much iron loss is generated owing to this field. In this paper, rotational power loss in the electrical machine under rotational magnetic field is discussed. Until now, loss analysis is based on the magnetic properties under alternating field. And with this one dimensional magnetic propertis, it is difficult to express iron loss under rotational field. In this paper, we used two dimensional magnetic property data for the numerical calculation of rotational power loss. We used finite element method for calculation and the analysis model is two dimensional magnetic property measurement system. We used permeability tensor instead of scalar permeability to present two dimensional magnetic properties. And in this case, we cannot uniquely define energy functional because of the asymmetry of the permeability tensor, so Galerkin method is used for finite element analysis.