• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.04a
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• pp.222-224
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• 1997

This study is about a connective method of High Tc wire for long wire. We prepared silver-sheathed BiPbSrCaCuO wires by the powder-in-tube method. Since the superconducting wires are ceramic, it is very hard to connect each other. In this study, we used a silver sleeve to contract wires and pressed them by various preasures. Then optimum preasure was 9,000 Kgf/$\textrm{cm}^2$ to get the high critical current. The higest critical current was 10A.

• The Korean Journal of Ceramics
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• v.5 no.3
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• pp.239-244
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• 1999

Ultrafine lead magnesium niobate $Pb(Mg_{1/3}Nb_{2/3}) O_3$ (PMN) powders have been successfully prepared via a micro-emulsion processing technique. By stepwise hydrolysis using aqueous as the precipitant, hydroxide precursor was obtained from nitrate solutions dispersed in the nanosized aqueous domains of a microemulsion consisting of cyclohexane, non-ionic surfactant (NP5+NP9) and an aueous phase. Upon calcination of the microemulsion-derived precursor at $800^{\circ}C$, PMN powders with 100% perovskite phase was obtained.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.115-118
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• 2003

The sensor at liquid nitrogen temperature showed the increase of electrical resistance by applying magnetic field. Actually, the voltage drop across the sensor was changed from zero to a value more than $100\;{\mu}V$ by the applied magnetic field. The change of electrical resistance depended on magnetic field. The sensitivity of this sensor was $2.9\;{\Omega}/T$. The sensing limit was about $1.5{\times}10^{-5}\;T$. The increase of electrical resistance by the magnetic field was ascribed to a modification of the Josephson junctions due to the penetrating magnetic flux into the superconducting material. 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.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.585-588
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• 2001

Thin. Boron-doped conducting diamond films are expected to be excellent electrodes for industrial electrolysis. Boron-doped conducting diamond films were used as anode for generating ozone gas by electrolysis of acidic solution. In this work, we have studied ozone generating system using Boron-doped Diamond electrode. Electrochemical cell and ozone generating system were designed for decreasing the temperature of the system. which was elevated during the reaction. by circulation of electrolyte in the system. In order to determine the ozone generation properties of diamond electrode. experimental conditions, electrolyte concentration, temperature, flow rate and reaction time were varied diversely. As a result, we could confirm that ozone gas was generated successfully and the performance of diamond electrode was stable while $PbO_2$ electrode was disintegrated. Actually we are found that ozone amount increased by lowering the temperature of electrolyte.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1988.05a
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• pp.88-91
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• 1988

In this paper, PLZT Ceramics were fabricated by two stage sintering method whose first stage vacuum hot pressing and second stage PbO atmosphere sintering. Using Graphite Mould instead of Alumina Mould in first stage prevented the adhision between PLZT substrate and the mould. The grain sizes of PLZT Ceramics were controlled by varying the hot pressing time and second sintering time.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2014.11a
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• pp.89-90
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• 2014

인쇄회로기판 패턴도금 박리공정 중 발생하는 폐솔더 박리액은 주석, 구리, 철, 납 등 유가금속이 함유된 질산계 폐액이다. 본 연구에서는 이러한 폐솔더 박리액에서 질산과 유가금속을 체계적으로 회수하는 기술을 개발하고자 하였다. 먼저 폐액을 $80^{\circ}C$에서 3시간 정도 반응시켜 주석을 $SnO_2$ 상태로 90% 이상 회수가 가능하였다. 주석이 회수되고 구리, 철, 납만이 존재하는 질산계 폐솔더 박리액에서 확산투석을 이용하여 질산을 94% 이상 회수가 가능하였고 회수된 질산의 농도는 5.1 N 이었다. 질산을 추출한 폐액에서 침전제로 옥살산(Oxalic acid)을 사용하여 구리를 구리옥살레이트 상태로 침전시켜 타금속이온과 선택적으로 분리하였다. 마지막으로 폐액 중 용해되어있는 납을 $65^{\circ}C$이상에서 철 스크랩을 이용한 세멘테이션을 통하여 회수하였다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.10
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• pp.855-860
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• 1998

This paper presents a new structure for a piezoelectric transformer, operating in thickness extensional vibration mode. Modified $PbTiO_3$ family ceramics were used for the piezoelectric transformer, because it was a material with large anisotropy between elecromechanical coupling factors $K_t$ and $K_p$ . The size of piezoelectric transformer was 20mn long, 20mm wide and 3.1mm thick. The second harmonic resonant frequency of thickness extensional vibration mode was 0.72MHz at loading resistance 100[$\omega$], And Voltage gin of piezoelectric ceramics showed 0.53 at resonant frequency of sencond thickness extensional vibration mode.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1477-1479
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• 2000

The annealing treatments on rf magnetron sputtered PZT($Pb_{1.05}(Zr_{0.52},Ti_{0.48})O_3$) thin films(4000${\AA}$) have been investigated for a structure of PZT/Pt/Ti/ITO coated glass. Crystallization properties of PZT films were strongly dependent on RTA(Rapid Thermal Annealing) annealing temperature and time. We were able to obtain a perovskite structure of PZT at 650$^{\circ}C$ and 10min. P-E curves of Pd/PZT/Pt capacitor demonstrate typical hysteresis loops. The measured values of $P_r$, $E_c$ were 15.8[${\mu}C/cm^2$], 95[kV/cm] respectively. Polarization value decrease about 10% after $10^9$ cycles.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.585-588
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• 2001

Thin, Boron-doped conducting diamond films are expected to be excellent electrodes for industrial electrolysis. Boron-doped conducting diamond films were used as anode for generating ozone gas by electrolysis of acidic solution. In this work, we have studied ozone generating system using Boron-doped Diamond electrode. Electrochemical cell and ozone generating system were designed for decreasing the temperature of the system, which was elevated during the reaction. by circulation of electrolyte in the system. In order to determine the ozone generation properties of diamond electrode, experimental conditions, electrolyte concentration, temperature, flow rate and reaction time were varied diversely. As a result, we could confirm that ozone gas was generated successfully and the performance of diamond electrode was stable while PbO$_2$ electrode was disintegrated. Actually we are found that ozone amount increased by lowering the temperature of electrolyte.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.11
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• pp.885-891
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• 2001

Ring/dot-type step-down piezoelectric transformer was manufactured by using Pb[(Mn$\sub$1/3/Sb$\sub$2/3)$\sub$0.05/Zr$\sub$0.475/Ti$\sub$0.475/]O$_3$ ceramics, which have excellent high-power piezoelectric properties. The characteristics of step-down piezoelectric transformer as a function of load resistance at output terminal was examined. Voltage gain was greatly dependent on drive frequency and load resistance, and showed maximum voltage gain at the resonance frequency. The output voltage was linearly increased as the input voltage increased. Voltage gain of the step-down piezoelectric transformer with respect to input voltage was very stable when the load resistance was in the range of 50-500 $\Omega$ .