• Progress in Superconductivity
• /
• v.5 no.2
• /
• pp.141-143
• /
• 2004

For designing a flywheel system using superconductor, it is necessary to understand the basic characteristics of the classical superconductor bearing. It is difficult to expect the characteristics of superconductor bearings using models that have been introduced up to now. In the "Frozen image" concept, the farce between the permanent magnet and the superconductor can be divided into two forces between permanent magnet and two imaginary magnets in the superconductor; one represents attraction farce and the other represents a repulsion force. We calculated the characteristics of two superconductor bearings, such as an axial, the radial stiffness and the levitation force. This calculation method was very helpful to expect the characteristics of the superconductor bearings. Using this model, we established the optimum condition for the superconductor bearing.r bearing.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.58 no.4
• /
• pp.535-537
• /
• 2009

As a kind of high Tc superconductor application technique, a study on the development of energy storage device system using BiPbSrCaCuO superconductor was performed. Chemical melt process was developed to gabricate the high magnetization superconductor which is needed to develop the energy saving system and the effect of various process variable on the superconducting properties of the specimens were tested and analyzed. Magnetochemical interactions between superconductor and permanent magnet was also experimented.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.14 no.6
• /
• pp.491-498
• /
• 2001

The relationship between electrical properties of YBaCuO superconductor and externally applied magnetic field was studied to develop a magnetic field apolarity sensor. The electrical resistance of the superconductor was increased by applying external magnetic field and even after removal of the magnetic field. The behavior was related to the magnetic flux trapped in the superconductor, which penetrates through the materials by the external magnetic field. Some portion of the superconductor was changed to a normal state by the trapped magnetic flux. The appearance of the normal state yielded to enhance the electrical resistance. Electrical characteristics of the superconductor with trapped magnetic flux were extremely sensitive to the external magnetic field and showed different responses depending on the direction of the magnetic field. Considering the observed properties of the superconductor with trapped magnetic flux, a magnetic sensor was fabricated to detect simultaneously both the intensity and the direction of the magnetic field.

• Progress in Superconductivity
• /
• v.2 no.2
• /
• pp.57-64
• /
• 2001

We have calculated the tunneling density of states (TDOS) of a metal/d-wave superconductor proximity junction, where the metal stands fur the normal metal, 5-wave superconductor, and d-wave superconductor. The tunneling direction is through the ab-plane of the d-wave superconductor. Because of the sign change in the order parameter experienced in the multiple Andreev reflection, there appears a finite TDOS at zero bias for duty geometry, which results in the anomalous zero bias conductance peak(ZBCP). For $d_{x2-y2}$ geometry, however, no TDOS peak appears at zero bias. We have calculated TDOS for various crystal orientation of HTSC and compared with the experimental conductance.

• Progress in Superconductivity
• /
• v.14 no.1
• /
• pp.66-70
• /
• 2012

Superconductor flywheel energy storage system (SFESs) is an electro-mechanical battery with high energy storage density, long life, and good environmental affinity. SFESs have been developed for application to a regenerative power of train, the storage of distributed power sources such as solar and wind power, and a power quality improvement. As superconductor bearing is completely passive, it is not necessary to control a system elaborately but accurate analysis in mechanical properties of the HTS bearing is very important for application to SFESs. Stiffness and damping properties are the main index for evaluation the capacity of HTS bearings and make it possible to adjust rotordynamic properties while operating the rotor-bearing system. The superconductor bearing consists of a stator containing single grain YBCO bulks, a ring-type permanent magnet rotor with a strong magnetic field that can reach the bulk surface, and a bearing support for assembly to SFESs frame. In this study, we investigated the stiffness and damping properties of superconductor bearings in 35 kWh SFESs. Finally, we found that 35 kWh superconductor bearing has uniform stiffness properties depend on the various orientations of rotor vibration. We discovered total damping coefficient of superconductor bearing is affected by not only magnetic damping in superconductor bulk but also external damping in bearing support. From the results, it is confirmed that the conducted evaluation can considerably improve energy storage efficiency of the SFESs, and these results can be used for the optimal capacity of superconductor bearings of the SFESs.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.04a
• /
• pp.21-24
• /
• 2002

In this paper, for the study on the fabrication of YBCO superconductor wire, a double layered YBCO superconductor wire was fabricated by electrophoretic method on metal Ag wire(${\Psi}$0.8 mm). On the basis of previous researches for the fabrication of superconductor wire, the acetone suspension solution with 8 vol.% of 1% PEG(1000) was used and high molecular adhesive was experimentally performed for an improvement of the critical current density of superconductor wire. It was found that the Ag inter-layer deposited on the superconductor wire affect to the state of second YBCO film and its critical current density.

• Progress in Superconductivity and Cryogenics
• /
• v.3 no.1
• /
• pp.22-28
• /
• 2001

A vortical axis flywheel system was conceptualized, which uses a hybrid superconductor bearing set to carry the wheel part load. The multiple designs of magnetic bearing and superconductor bearing were analyzed by using conventional numerical magnetostatic analysis method The best medels were selected among four different types of Permanent magnet bearings for upper bearing and two types of superconductor bearing for lower bearing, respectively These results were discussed in regard of application to the flywheel system with a Passive hybrid magnetic bearing set.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.55 no.4
• /
• pp.213-216
• /
• 2006

The magnetic levitation effect a high Tc superconductor beneath the toroidal permanent magnet was examined by means of a improved magnetic seesaw method. Magnetic effects associated with penetration and pinning in superconductor. One of these was focussing of magnetic field by superconductor and the other was magnetic levitation. The existence of equilibrium was shown to be related to hysteresis observed in the force separation for a toroidal permanent magnet and superconductor. Obtained results indicate that magnetic levitation effect in the present case was mainly due to diamagnetic effect.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
• /
• 2003.02a
• /
• pp.137-139
• /
• 2003

The relationship between magnetic properties of BiPbSrCaCuO superconductor and externally applied magnetic field was studied to develop a magnetic field polarity sensor. The behavior was related to the magnetic flux trapped in the superconductor, which penetrates through the material by the external magnetic field. Some portion of the superconductor was changed to a normal state by the trapped magnetic flux. Electrical characteristics of the superconductor with trapped magnetic flux were extremely sensitive to the external magnetic field and showed different responses depending on the direction of the magnetic field.

• Proceedings of the KIEE Conference
• /
• 2003.07c
• /
• pp.1421-1423
• /
• 2003

The relationship between magnetic properties of BiPbSrCaCuo superconductor and externally applied magnetic field was studied to develop a magnetic field polarity sensor. The behavior was related to the magnetic flux trapped in the superconductor, which penetrates through the material by the external magnetic field. Some portion of the superconductor was changed to a normal state by the trapped magnetic flux. Electrical characteristics of the superconductor with trapped magnetic flux were extremely sensitive to the external magnetic field and showed different responses depending on the direction of the magnetic field.