• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.1
• /
• pp.559-562
• /
• 2004

The $high-T_c$ Superconducting(HTS) antenna which consists of "H" type resonator has the benefits for the miniaturization of antenna in comparison with the microstrip antenna of the similar dimension. To fabricate the "H" type antenna HTS $YBa_2Cu_3O_{7-x}$(YBCO) thin films were deposited on MgO substrates using rf-magnetron sputtering. Standard etching processes were performed for the patterning of the "H" type antenna. For comparison between normal conducting antennas and superconducting antennas, the gold antennas with the same dimension were also fabricated. An aperture coupling was used for impedance matching between $50\Omega$ feed line and HTS radiating patch. The diverse experimental results were reported in terms of the resonant frequency, the return loss and the characteristics impedance. The "H" type superconducting antenna showed the performance of 1.36 in SWR, 24 % in efficiency, and 14.6 dB in the return loss superior to the normal conducting counterpart.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
• /
• pp.282-283
• /
• 2005

Ion beam assisted deposition(IBAD) technique was used to produce biaxially textured polycrystalline MgO thin films for high critical current YBCO coated conductor. Hastelloy tapes were continuous electropolished with very smooth surface for IBAD-MgO deposition, RMS roughness of Hastelloy tape values below 2 nm and local slope of less than $1^{\circ}$. After the polishing of the tape an amorphous $Y_2O_3$ and $Al_2O_3$ are deposited Biaxially textured MgO was deposited on amorphous layer bye-beam evaporation with a simultaneous bombardment of high energy ions. We had developed the RHEED to measure in-situ biaxial texture of film surface as thin as tens angstrom. And also ex-situ characterization of buffer layers was studied using XRD and SEM. The full-width at half maximum(FWHM) out of plane texture of IBAD-MgO template is $4^{\circ}$.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2004년도 하계학술대회 논문집 C
• /
• pp.1745-1747
• /
• 2004

In order to anticipate gradual increase of fault current in electric power systems, current limiting technology and current limiting device has been investigated for a long time. But the commercial use of current limiting device was delayed due to the lack of effective method to insert impedance to the elective power systems without loss and surplus defects. However, novel current limiting device, which use superconducting materials, was considered as a dream technology to be applied in a distribution and transmission lines. LG Industrial systems and KERPI started to investigate resistive type superconducting fault current limiters in order to develop 154kV fault current limiters and this year, we succeed to test 3 phase 6.6kV/200A fault current limiters. Based on these achievements, 24kV superconducting fault current limiters will be realized withing 3 years which could be tested in a real fields. In this paper, the developments of fault current limiting module which use YBCO thin films, cryogenic systems, the structure and construction of 3 phase fault current limiters and finally the test results of 6.6kV superconducting fault current limiters will be introduced.

• 한국조명전기설비학회:학술대회논문집
• /
• 한국조명전기설비학회 2006년도 춘계학술대회 논문집
• /
• pp.467-470
• /
• 2006

Superconducting fault current(SFCLs) are expected to improve not only reliability but also stability of real power systems. The analysis on the single line-to-ground fault current of the integrated three phase flux-lock type SFCL, which consists of three flux-lock reactor wound on an iron core in each single phase and three YBCO thin films, was investigated in current limiting operating characteristics. We compared additive polarity winding with the subtractive one in the flux lock reactor. Its turns ratio each phase between the primary and the secondary coils is 63:42. When a single line-to-ground fault occurred in any phase, the peak value of line current in the fault phase of the additive polarity winding increased up to 31.44[A] during first-half cycle. On the other hand, the peak value in the subtractive polarity winding increased up to 81.77[A] under the same conditions. This is because the current flow between the primary and the secondary windings becomes to be additive or subtractive in each winding direction. We confirmed that the current limiting behavior in the additive polarity winding was more effective for a single-line-to ground fault.

• 한국전기전자재료학회논문지
• /
• 제17권11호
• /
• pp.1241-1245
• /
• 2004

Continuous physical vapor deposition (PVD) method is one of many processes to fabricate long length coated conductor which is required for successful large-scale application of superconducting power devices. Three film deposition systems (pulsed laser deposition, sputtering, and evaporation) equipped with reel-to-reel(R2R) metal tape moving apparatus were installed and used to deposit multi-layer oxide thin films. Both RABiTS and IBAD texture templates are used. IBAD template consists of CeO$_2$(PLD)/YSZ(IBAD) on stainless steel(SS) metal tape, and RABiTS template has the structure of CeO$_2$/YSZ/Y$_2$O$_3$ which was continuously deposited on Ni-alloy tape using R$_2$R evaporation and DC reactive sputtering in a deposition system designed to do both processes. 0.4 m-long coated conductor with Ic(77 K) of 34 A/cm was fabricated using RABiTS template. 0.5 m and 1.1 m-long coated conductor with Ic(77 K) of 41 A/cm and 26 A/cm were fabricated using IBAD template.