• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.342-343
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• 2009

Paper factories use a large amount of water and same amount of wastewater is generated. It is important to purity and recycle the wastewater because of water shortages and water pollution. The existing water treatment facilities like precipitation process need large-scale equipment and wide space to purity the wastewater of paper factory. High gradient magnetic separation (HGMS) system has the merits to purity rapidly because of large voids at filter and to occupy small space. In this paper, two types of superconducting magnets were used for HGMS systems. Cryo-cooled Bi-2223 superconducting magnet system with 70 mm room temperature bore and 200 mm of height was prepared. Cryo-cooled Nb-Ti superconducting magnet with 100 mm room temperature bore and 600 mm of height was used for magnetic separator. Magnetic filters were designed by the analysis of magnetic field distribution at superconducting magnets. The various magnetic seeding reactions were investigated to increase the reactivity of coagulation. The effects of magnetic separation of wastewater were investigated as variation of magnetic field strength and flow rate of wastewater.

• 한국초전도학회:학술대회논문집
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• v.12
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• pp.42-42
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• 2002

• Progress in Superconductivity
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• v.4 no.2
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• pp.132-136
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• 2003

Extremely selective high temperature superconducting (HTS) band -pass filters were developed for the base transceiver station applications of Digital Cellular communication Service (DCS). The filters have a bandwidth of 25 MHz at a center frequency of 834 MHz. There are 12 resonators which have spiral-meander microstrip-line structures in order to reduce far-field radiations with a reasonable tunability. As a result, the size of filters is 5 mm $\times$ 17 mm $\times$ 41 mm. Device characteristics exhibited a low insertion loss of -0.4 dB with a -0.2 dB ripple and a return loss better than -10 dB in the pass-band at 65 K. The out-of-band signals were attenuated better than 60 dB about 3.5 MHz from the lower band edge, and 3.8 MHz from the higher band edge.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.44-44
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• 2010

Conventional water treatment facilities like precipitation process need large-scale equipment and wide space to purify the wastewater of paper factory. In case of massive waste water, high gradient magnetic separation (HGMS) parts are more effective to purify it rapidly and to occupy relatively small space, since large voids at filter with HGMS are adopted. Cryo-cooled Nb-Ti superconducting magnet with room temperature bore in diameter of 100 mm and 600 mm in height was used for magnetic separator. Magnetic filters were designed by the analysis of magnetic field distribution at superconducting magnets.

• Progress in Superconductivity and Cryogenics
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• v.11 no.4
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• pp.8-11
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• 2009

This study introduced wastewater treatment method by High Gradient Magnetic Separation (HGMS). HGMS treatment was high efficient method for various industrial wastewaters. The system is currently research state, but we have surveyed commercialize the technology for industry. In rolling plate process, coolant wastewater was recycled by sedimentation and sand filter system. It needs several large reservoirs and long time to remove suspended solid (SS) like metal fines and iron oxide in hot rolling plate making process. If removing rate of suspended solid in rolling coolant wastewater is improved by using HGMS system, the productivity of working process can be increased and the area of reservoir can be reduced. We manufactured high temperature superconducting HGMS system that had a purpose to treatment of coolant wastewater in rolling plate process. We fabricated the prototypes of magnetic matrix filter consisting of stainless steel 430 mesh, which is a core component in the magnetic separation system, In our basic preliminary experiment using HGMS system, it has been clear that the fine paramagnetic particles in the coolant wastewater obtained from rolling plate process of POSCO can be separated with high efficiency.

• 한국초전도학회:학술대회논문집
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• v.9
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• pp.138-141
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• 1999

For the enhancement of communication system performance, high quality filters are required. Conventional metal filters made of copper can be substituted by high quality high temperature superconductivity(HIS) flms for better performance. In order to reduce the size of the filter for the integration of device in the limited area, we have fabricated hairpin type filters using pulsed laser deposition(PLD) technique. The superconducting YBCO thin films have been grown on MgO substrates by PLD with Nd:YAC laser. The YBCO films were patterned by conventional wet-etching process. We have compared YBCO filters and copper filters which were made with the same spec. Simulated and measured frequency responses reveal that HIS YBCO hairpin type bandpass filters show better performance than copper filters.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.12
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• pp.11-20
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• 1999

We have designed and fabricated direct-and gap-coupled microstrip hairpin-comb filters by patterning double-sided YBCO films on a single 50-mm-diameter, 0.5-mm-thick $LaAlO_3$ wafer. Both filters have a center frequency at 1.773 GHz, 12 MHz bandwidth, 0.5 dB minimum insertion loss in the passband, and very strong out-of- band rejection. Due to two attenuation poles below and above the passband, the direct-coupled hairpin-comb filter showed a better skirt characteristic than the gapcoupled hairpin-comb filter which had only one attenuation pole below the passband.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.958-960
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• 2002

High Temperature Superconducting (HTS) devices make it possible to operate with no electrical loss by resistance. If, however, the applied current is over its critical current, the phase of HTS devices is changed to normal state, so called, quench. In this case, since resistance of HTS is increased abruptly, it can not be avoidable to damage the whole apparatus. In this study, quench detector to protect HTS devices was proposed. We designed the quench detecting circuit and tested the performance of the circuit. The detecting circuit was consisted of Op-Amp and low pass filter etc, to detect very low voltage around $1{\mu}V$. The circuit detected effectively the low voltage when over current is applied to HTS tapes. At the next step, we are going to apply and test the circuit to protect the prototype HTS cable.