• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.7
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• pp.1067-1074
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• 1994

This paper deals with the combined levitation and guidance EDS(Electrodynamic Suspension) Maglev system. Levitation and guidance forces generated in figured-of-eight coil are examined. End effect of Superconducting magnets is considered in that the air gap flux has been calculated using the finite number of magnets. Induced emfs and currents of ground coils are given as results. Eletromagnetic forces vary according to the built-in position of magnets. Levitation forces of the first magnet pair are the smellest and those of the second one are the largest. This result shows that the end effect of SCMs should be considered in a concentrated magnet system.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.735-737
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• 2000

An axial-flux permanent-magnet machine(AFPM) topology with coreless winding is proposed. In the proposed AFPM configuration. the winding consists of a hexagon-shaped coils encapsulated in fiber-reinforced epoxy resin. Due to the lack of the iron core. the overall machine structure has high compactness and lightness. The simplified design calculation of the back emf was obtained. In this study, motor design was carried out using the software package Maxwell. This paper discusses the basic design of coil winding of AFPM motor. Experimental results were taken form a prototype machine rated 0.4 Nm, 2000 rpm.

• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.235-237
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• 1999

This paper has proposed a method to estimate effective length of a 30 KVA super-conducting generator using 3-dimensional FEM program. Flux linkage of the stator coil is calculated by the FEM program and the induced voltage is computed using the simple Faraday's law.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.666-668
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• 2000

The LIMs performance on-line monitoring system is proposed by using LabVIEW software and A/D board. The on-line monitoring system set-up can measure input voltage. current, power, power factor, electromagnetic thrust, and efficiency etc. This paper reports data on LIM performance measured by the proposed on-line monitoring system.

• Proceedings of the KIEE Conference
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• 1998.07a
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• pp.250-253
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• 1998

This paper has proposed a method to analyze a 30 KVA superconducting generator using 3-dimensional FEM program. 3 kinds of 3D formulation methods are employed such as scalar potential in core region, reduced scalar potential in air region and T-${\omega}$ formulation in stator coil region. As results of the simulation, various parameters of the generator have been analyzed like air gap flux density, induced voltage, inductance, etc.

• Nuclear Engineering and Technology
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• v.38 no.8
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• pp.753-762
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• 2006

In this paper, works related to enhancement of the CHF are reviewed in terms of fundamental mechanisms and practical applications. Studies on CHF enhancement in forced convection are divided into two categories, CHF enhancement of internal flow in tubes and enhancement of CHF in the nuclear fuel bundle. Methods of enhancing the CHF of internal flows in tubes include enhancement of the swirl flow using twisted tapes, a helical coil, and a grooved surface; promotion of flow mixing using a hypervapotron; altering the characteristics of the heated surface using porous coatings and nano-fluids; and changing the surface tension of the fluid using additives such as surfactants. In the fuel bundle, mixing vanes or wire wrapped rods can be employed to enhance the CHF by changing the flow distributions. These methods can be applied to practical heat exchange systems such as nuclear reactors, fossil boilers, fusion reactors, etc.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.11
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• pp.658-663
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• 2004

According to the improvement of the HTS wires performance, several tapes of HTS superconducting machines are being developed. Stacked HTS tapes are used as conductor that can flow high current for the HTS power machines. To develop the HTS power machines, the critical current characteristics of a stacked HTS tapes in external filed and AC losses should be examined. In this paper, we present characteristic of the stacked HTS tapes and AC losses of HTS pancake windings with stacked tapes. AC loss of the pancake winding were measured and compared with the calculated loss by using AC loss data of the stacked samples and the magnetic flux density in the HTS winding under operating conditions. We can see that measured results generally agree well with the calculated results by using AC loss data of 4-stacked sample.

• Proceedings of the KIEE Conference
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• summer
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• pp.776-778
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• 2004

In this paper, we present effect of the stacked HTS tapes. AC losses of HTS pancake windings with stacked tapes are shown. Magnetic flux density in the HTS winding under operating conditions was calculated by FEM. AC loss of the pancake winding were measured and compared with the calculated loss by using AC losses of the stacked samples. Test results show that measured results generally agreed well with the calculated value by using AC loss of 4-stacked sample data.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.1
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• pp.21-26
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• 2006

This paper deals with the dynamic analysis and experiments of moving-magnet linear actuator with/without spring. On the basis of two dimensional (2-D) analytical solutions and experiments, control parameters such as thrust constant, back-emf constant, inductance and resistance are obtained. And then, dynamic simulation algorithm is established from the voltage and motion equation. Finally, for various values of frequency, dynamic simulation results for characteristics of current and displacement of moving-magnet linear actuator with and without spring are presented and confirmed through the experiments. In particular, This paper applies the PWM voltage waveform obtained from a DSP for bidirectional voltage drive to the actuator.

• Proceedings of the KIEE Conference
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• 1999.07g
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• pp.3328-3330
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• 1999

In this paper, the fabrication of a micro actuator with a micro electromagnet and an actuator diaphragm is presented. The micro electromagnet consists of a magnetic core and a micro inductive planar coil. The actuator diaphragm is the p+ silicon diaphragm on both sides of which magnetostrictive materials are deposited by sputtering. The micro electromagnet is fabricated by sputtering, evaporating, etching and electroplating. The magnetic flux density of the micro electromagnet is measured by using the gauss meter. The deflection of the actuator diaphragm is measured by using the laser vibrometer and optic microscope.