• 한국초전도학회:학술대회논문집
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• 2008.08a
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• pp.56-56
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• 2008

• 한국초전도학회:학술대회논문집
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• 2007.07a
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• pp.44-44
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• 2007

• Progress in Superconductivity
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• v.8 no.2
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• pp.127-131
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• 2007

We have measured the Hall conductivity (${\sigma}_{xy}$) of c-axis-oriented $MgB_2$ thin films as functions of temperatures and magnetic fields. We found that the Hall conductivity (${\sigma}_{xy}$) is expressed by the sum of two terms, ${\sigma}_{xy}=C_l/H+C_3H$, where the coefficient $C_1\;and\;C_3$ are independent of the magnetic fields and have positive values. The coefficient $C_1$ is strongly dependent on the temperature, while the $C_3$ is weakly dependent on the temperature. We have obtained that the $C_1$ is proportional to $(1- T/T_c)^n$ with n = 4.2, which is consistent with the data observed in $La_{2-x}Sr_xCuO_4$ superconductors with low anisotropy ratio.

• 한국초전도학회:학술대회논문집
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• 2008.08a
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• pp.45-45
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• 2008

• Proceedings of the Korean Vacuum Society Conference
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• 2002.06a
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• pp.151-151
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• 2002

• 한국초전도학회:학술대회논문집
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• v.16
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• pp.49-49
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• 2006

• Journal of Surface Science and Engineering
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• v.44 no.2
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• pp.44-49
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• 2011

The films formed on AZ31B magnesium alloy were prepared from alkaline solution composed of potassium permanganate and sodium hydroxide. The immersion tests were carried out at the different concentration of sodium hydroxide and pre-treatment method in 5 minute. The morphology and the phase composition of the film were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The corrosion behavior of the film in 5.0% NaCl solution was evaluated using potentiodyanmic polarization. Open circuit potential in developing film was examined with time. The thin and transparent film was mainly composed of MgO and $Mg(OH)_2$. The film with the best corrosion resistance was obtained at $70^{\circ}C$ bath temperature, 1.6 M concentration of sodium hydroxide and chemical pre-treatment.

• 한국초전도학회:학술대회논문집
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• v.10
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• pp.35-39
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• 2000

Large-area high-temperature superconducting (HTS) films, filter design and damage-free processing technique have been developed to fabricate low insertion loss and sharp skirt filters. Further, long life cryocooler, low temperature low noise amplifier (LNA) and cryocable have been developed to assemble HTS filter subsystem for IS-95 and IMT-2000 mobile telecommunication. The surface resistance of the films was about 0.2 milli-ohm at 70 K, 12 GHz. An 11-pole HTS filter for IS-95 telecommunication system and a 16-pole HTS filter for IMT-2000 telecommunication system were designed and fabricated using 60 {\times}$ 50 mm$^2$ and one half of 3-inch diameter YBCO films on a 0.5-mm-thick MgO substrate, respectively. We have assembled the filter and low temperature LNA in a dewar with the cryocooler. Ultra low-noise (noise figure: 0.5 dB at 70 K) and ultra sharp-skirt (40 dB/1.5 MHz) performance was presented by the IS-95 filter subsystem and the IMT-2000 filter subsystem, respectively.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1858-1860
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• 1999

To fabricate superconducting multiplexers with narrow pass band characteristics and reduce the physical size of device, we have designed multiplexer using hair-pin type filters with the center frequency of 13.6 GHz. Multiplexers have been fabricated superconductor(HTS), because It has low surface resistance. The $YBa_2Cu_3O_{7-{\delta}}$(YBCO) films were deposited on MgO substrates$(20{\times}20{\times}0.5mm^3)$ by using pulsed laser deposition and conventional photo-lithographic methods were used to pattern the multiplexer. Epitaxial YBCO films were grown on(100) MgO substrates and showed strongly c_axis orientations observed by X-ray diffraction technique. Superconducting transition temperatures were measured to be about 89K. Simulated results of superconducting multiplexer consisting of hair-pin type filters show the insertion loss of about 1.2dB. The measured frequency response will be compared with the simulated results.

• Journal of Sensor Science and Technology
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• v.5 no.3
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• pp.87-92
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• 1996

The PLT thin films on (100) cleaved MgO single crystal substrate have been fabricated by rf magnetron sputtering using a PbO-rich target. The dependence of physical and electrical properties on the degree of c-axis orientation has been studied. The degree of c-axis orientation of PLT thin films depends on fabrication conditions. Fabrication conditions of the PLT thin films were such that substrate temperature, working pressure, gas ratio of $Ar/O_{2}$, and rf power density were $640^{\circ}C$, 10 mTorr, 10 seem, and $1.7\;W/cm^{2}$, respectively. In these conditions, the PLT thin film showed the Pb/Ti ratio of 1/2 at the surface, the resistivity of $8{\times}10^{11}{\Omega}{\cdot}cm$, and dielectric constant of 110. The pyroelectric infrared sensors with these PLT thin films showed the peak to peak voltage of 450 m V and signal to noise ratio of 7.2.