• 한국초전도학회:학술대회논문집
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• 2007.07a
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• pp.24-24
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• 2007

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.295-295
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• 2008

This study introduced waste water treatment method applied superconductor HGMS(High Gradient Magnetic Separation). HGMS method treat high efficient method for various waste water. we have surveyed superconducting magnetic separation technology and reviewed the status of related industries using applied superconductivity. We fabricated the prototypes of magnetic matrix filter consisting of stainless steel mesh, which is a core component in the magnetic separation system. In our basic preliminary experiment using HGMS, it was made clear that the fine para-magnetic particles in the rolling colling wasted water obtained from rolling process of POSCO can be separated with high efficiency.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.4
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• pp.98-105
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• 1996

The design method of 85 GHz-115 GHz band single side-band filter using the principle of martin-puplett inteferometer is described. It has been designed by this method and also manufactured and tested. From the test results, not only the ratio of image singal rejection of 19 dB is obtained, but also the theoretical and experimental results of center frequency of pass-band and rejection-band show the validity of the theory. This manufactured filter was installed on 100GHz band SiS (superconductor insulator superconductor ) receiver for observing cosmic radio waves and tested. We found that this filter can be used a single side-band as well as double side-band mode. The design method which is presented in this paper can be used a single side-band filter for a heterodyne type sub-milimeter wave receiver.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.787-789
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• 2000

High temperature superconducting YBCO films have been grown on MgO substrates by pulsed laser deposition (PLD) with Nd:YAG laser Superconducting microwave filter was fabricated by conventional photolithography method. We have designed filter with the center frequency of 14 GHz. We have measured the center frequency of filter at 77 K and its critical temperature 89K. Also we have designed another filter to compare frequency responses. The measured frequency responses will be presented.

• Progress in Superconductivity
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• v.13 no.3
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• pp.195-202
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• 2012

In this paper, we designed Active Magnetic Bearing (AMB) for large scale Superconductor Flywheel Energy Storage System (SFESS) and PD controller for AMB. And we experimentally evaluated SFESS including hybrid type AMB. The radial AMB was designed to provide force slew rate that was sufficient for the unbalance disturbances at the maximum operating speed. The thrust AMB is a hybrid type where a permanent magnet carries the weight of the flywheel and an electromagnetic actuator generates the dynamic control force. We evaluated the design performance of the manufactured AMB through comparison of FEM analysis and the results of experimental force measurement. In order to obtain gains of PD controller and design a notch filter, the system identification was performed through measuring frequency response including dynamics for the AMBs, a power amp and a sensor using a sine swept test method after levitating the flywheel. Through measuring the current input of the AMBs and the orbit of a flywheel according to rotational speed, we verified excellent control performance of the AMBs with small amount current for the large scale SFESS.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2002.02a
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• pp.159-162
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• 2002

The eleventh-order coupled line lowpass filter(LPF) was designed to suppress harmonics and spurious signals. The microstrip type LPF was fabricated using a high-$T_{c}$ superconductor(HTS) $YBa_{2}$$Cu_{3}$$O_{7-x}$(YBCO) thin film with the $CeO_{2}$ buffer layer which was deposited on the sapphire ($Al_{2}O_{3}$) substrate of 30 x 30 $mm^{2}$. The coupled-line type LPF was designed for 1.2 GHz of cutoff frequency with 0.01 dB of ripple level at passband. The fabricated HTS LPF shows excellent attenuation characteristics in stopband of 1.2~9.5GHz (7-attenuation poles in the stopband), and shows low insertion loss (0.2 dB) and return loss (17.1 dB) in the pass- band. These measured results match well with those obtained by the EM simulation. This clearly demonstrates that the HTS LPF can suppress harmonics and spurious signals effectively.

• Progress in Superconductivity
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• v.1 no.1
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• pp.42-46
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• 1999

A high-temperature superconducting 1.78 GHz bandpass filter, designed for PCS applications, is presented. The structure consists of microstrip pseudo-lumped elements, which enables miniaturization of the filter. A 5-pole microstrip filter could be realized on a 37 mm $\times$ 9 mm $LaAlO_3$ substrate, using double-sided high-temperature superconducting $YBa_2Cu_3O{7-\delta}$ thin film. This filter showed 0.7 % fractional bandwidth, 0.3 dB insertion loss, and 12 dB return loss in the passband at 60 K.

• Progress in Superconductivity and Cryogenics
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• v.6 no.4
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• pp.46-50
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• 2004

The Experimental results of the in-line type inertance tube pulse tube cryocooler for cooling superconductor RF filter are presented in this paper. The pulse tube refrigerator, which has no moving parts at its cold section, is attractive in obtaining higher reliability, simpler construction, and lower vibration than any other small refrigerators. The purpose of this study is to analyze the characteristics of in-line type inertance tube pulse tube refrigerator (IPTR), and to get main factor to improve the performance of the in-line type IPTR. Firstly, design parameters of the in-line IPTR are discussed by ARCOPTR program, and then to find optimal conditions of in-line type IPTR, cool down characteristics according to the variations of the charging pressure, inertance tube volume, regenerator volume and pulse tube volume are measured by the experiment. The lowest temperature of the cold end was about 50 K. Cooling capacity was the highest in the charging pressure of 32 atm. and 5W at 72K. On the other hand, COP of the in-line type IPTR was the highest in the charging pressure of 21 atm. and 0.018 at 77K.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.794-797
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• 2000

The fabrication of high quality superconducting thin films using pulsed laser deposition (PLD) has been reported to find optimized processing conditions and to make the millimeter-wave devices. High temperature superconducting (HTS) YBCO films were prepared on MgO (10${\times}$10${\times}$0.5mm) substrates by the PLD. The 3 pole bandpass filter with the center frequency of 22 GHz for satellite communication was designed consisting of hairpin coupled-lines to reduce the configuration in size. YBCO films are c-axis oriented and show superconductive transition temperatures of 88∼89 K with the transition widths < 0.5 K. The insertion loss of passband at 70 K was about 5 dB. The measured frequency response of superconducting filter will be compared with the simulation result.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.05a
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• pp.26-30
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• 1995

We describe the preparation and characterization of epitaxial thin films made with high temperature superconductor, $YBa_2Cu_3O_{7-\delta}$. The influence of processing parameters for YBCO thin films on MgO substrates in-situ grown by the pulsed laser deposition, including parameters of a laser beam energy, oxygen pressure, substrate temperature, target-substrate dis-tance is discussed. The characteristics of YBCO thin films were analyzed by using XRD, R-T measurement, AFM, crosssectional TEM, and RBS. For examples of microwave device applications, The fabrication and characterization of the microstrip lowpass filter and bandpass filter are also presented.