• Progress in Superconductivity and Cryogenics
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• v.18 no.2
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• pp.37-41
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• 2016

This paper presents the developed quench analysis code and protection circuit design for a superconducting magnet system of 28GHz electron cyclotron resonance (ECR) ion source. The superconducting magnet is composed of a hexapole magnet and four solenoid magnets located outside of the hexapole one. All magnets are wound with NbTi composite wire and impregnated by epoxy. By using the developed characteristic analysis code, the normal zone resistance, decaying current and temperature rising can be estimated during quench. Also, the stored magnetic energy is successfully consumed from the series resistor of the designed protection circuit. The analytical results are compared with the experimental results to verify the developed quench analysis code and protection circuit.

• KIEE International Transactions on Electrophysics and Applications
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• v.11C no.2
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• pp.18-22
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• 2001

The thin films of high permitivity in ferroelectric materials using a capacitor are applied to DRAMs and FRAMs. (Ba, Sr)TiO$_3$ thin as ferroelectric materials were prepared by the sol-gel method and made by spin-coating on the Pt/Sio$_2$/Si substrate at 4,000 [rpm] for 10 seconds. The structural characteristics of the surface were analyzed by fractal dimension. The thickness of BST ceramics thin films was about 260∼280 [nm]. The property of the leakage current was stable with 10-9∼10-11[A] when the applied voltage was 0∼3[V]. BST thin films ha low leakage current properties when fractal dimension was low and a coating area was high.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.05a
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• pp.344-349
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• 2001

This paper was to investigate of a adhesiveness for the plasma sprayed coating materials did salt spray by acoustic emission method in tensile loadings. The powders used for the coating were nickel aluminum composite powder Ni-4,5wt.%Al and titanium dioxide powder Ti02. These powders were coated on a carbon steel S45C by plasma spray method. The salt solution was a 5% NaCl and the salt spray times were 2, 5 and 10 hours respectively. The salt solution penetrated into the surface of the substrate through pore of the coating layer built in the process of plasma spay. Corrosion productions formed on the surface of substrate. The adhesiveness between the substrate and the coating layer is weaken by corrosion and the exfoliation initiated chiefly at the corrosion surface of the substrate. The AE events and energy of the corroded coating specimens decreased as the salt spray times increased.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.118-121
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• 1999

PLZT thin films were fabricated with different energy density by pulsed laser deposition. PLZT films deposited on Pt/Ti/SiO$_2$/Sr substrate. This PLZT thin films of 5000$\AA$ thickness were crystallized at $600^{\circ}C$, 200mTorr $O_2$ pressure for 2 J/$\textrm{cm}^2$ laser energy density. 14/50/50 PLZT thin film showed a maximum dielectric constant value of $\varepsilon$$_{r}$=1289.9 P-E hysteresis loop of 14/ 50/50 PLZT thin film was slim ferroelectric. Leakage current density of 14/50/50 PLZT thin film was 10/ sup -7/=A/$\textrm{cm}^2$.>.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.89-90
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• 2006

Austenitic stainless steel has been used as a corrosion resistance material. However, austenitic stainless steel has poor wear resistance property due to its low hardness. In this investigation, we apply powder composite process to obtain hard layer of Stainless steel. The composite material was fabricated from planetary ball milled SUS316L stainless steel powder and WC powder and then sintered by Pulsed Current Sintering (PCS) method. We also added TiC powder as a hard particle in WC layer. Evaluations of wear properties were performed by pin-on-disk wear testing machine, and a remarkable improvement in wear resistance property was obtained.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.150-151
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• 2006

Laser pyrolysis is a very suitable method for the synthesis of a wide range of nanoparticles. A pilot unit based on this process has been recently developed at CEA. This paper reports results showing the possibility to produce SiC and $TiO_2$ nanoparticles at rates of respectively 1 and 0.2 kg/h and also the possibility to adjust the mean grain size of the particles and their structure by changing the laser intensity and reactants flow rates. First tests of liquid recovery have been also successfully performed to limit the risks of nanoparticles dissemination in the environement during their recovery.

• Journal of Korean Vacuum Science & Technology
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• v.2 no.2
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• pp.92-96
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• 1998

Ferroelectric Bi-layered oxides SrBi2Ta2O9 (SBT) thin films have been deposited on Pt/Ti/SiO2/Si substrates using multi-target sputtering. Structure, composition, and electrical properties have been investigated on films. The SBT films were deposited with the various bismuth sputtering powers. The SBT films deposited with the bismuth sputtering power of 20 W have the most dense microstructure and the remanent polarization (Pr) of 9.2 ${\mu}$C/cm and the coercive field (Ec) of 43.8 kV/cm at an applied voltage of 5V. The SBT films deposited with the bismuth sputtering power of 20W showed a fatigue-free characteristics up to 1.0${\times}$1010 cycles under 5V bipolar pulse and a leakage current density of 2.0${\times}$10-8 A/$\textrm{cm}^2$ at 200 kV/cm.

• Biotechnology and Bioprocess Engineering:BBE
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• v.9 no.5
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• pp.374-378
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• 2004

The effects of various environmental factors such as pH (5, 6, 7, 8 and 9), temperature (30, 37 and $40^{\circ}C$) and rotational speed (150, 200 and 250 rpm) on the growth and the hepatitis B core antigen (HBcAg) production of Escherichia coli W3110IQ were examined in the present Study. The highest growth rate is achieved at pH 7, $37^{\circ}C$ and at a rotational Speed of 250 rpm which is 0.927 $h^{-1}$. The effect of pH on cell growth is more substantial compared to other parameters; it recorded a $123\%$ different between the highest growth rate (0.927 $h^{-1}$) at pH 7 and lowest growth at pH 5. The highest protein yield is achieved at pH 9, rotational speed of 250 rpm and $40^{\circ}C$. The yield of protein at pH 7 is $154\%$ higher compared to the lowest yield achieved at pH 5. There is about $28\%$ different of the protein yield for the E. coli cultivated at 250 rpm compared to that at 150 rpm which has the lowest HBcAg yield. The yield of protein at $40^{\circ}C$ is $38\%$ higher compared to the lowest yield achieved at $30^{\circ}C$.

• Progress in Superconductivity
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• v.8 no.1
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• pp.75-80
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• 2006

[ $Yb_2O_3$ ] films were successfully deposited on a cube-textured Ni and(100) $SrTiO_3$(STO) single crystal substrates by metal organic chemical vapor deposition(MOCVD) method using $H_2O$ vapor as an oxidant. $H_2O$ vapor was used in order to avoid the oxidation of Ni substrate. The working pressure and Ar flow rate were 10 Ton and 600 sccm, respectively. $Yb_2O_3$ films on STO were formed at high temperatures above $900^{\circ}C$. While XRD peaks from $Yb_2O_3$ were hardly detected at $900^{\circ}C$, the $Yb_2O_3$(400) texture was developed fur the films grown at deposition temperatures above $950^{\circ}C$. The AEM surface roughness of $Yb_2O_3$ film, grown on STO, was in the range of $6{\sim}10nm$ for the film deposited at $950^{\circ}C$ with a $H_2O$ vapor partial pressure of 5.5 Ton and deposition times of 3 and 5 mins. For cube-textured Ni substrate, both $Yb_2O_3$(222) and $Yb_2O_3$ (400) textures were developed textures at deposition temperatures above $850^{\circ}C$.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1661-1663
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• 2000

This study was to measure the dielectric characteristics of 0.05Pb($Al_{0.5}Nb_{0.5}$)-0.95Pb($Zr_{0.52}Ti_{0.48})O_3$[PAN-PZT] system ceramics according to the variation of $Cr_{2}O_3$, $Fe_{2}O_3$ addition amount. 0.0$\sim$1.2[wt%] and according to sintering temperature after creating the specimens with a general sintering way. The results of this study were summarized as follows : the dielectric constant at 20[$^{\circ}C$] reduced dy increasing additive on the whole. The dielectric loss was minimum value of 12.77[%], sintered at 1200[$^{\circ}C$], dopped with $Cr_{2}O_3$ 0.3[wt%] and minimum value of 10.89[%], sintered at 1200[$^{\circ}C$], dopped with $Fe_{2}O_3$ 0.6[wt%]. The variation rate of dielectric constant according to the change of frequency was decreased slowly by increasing frequency. The temperature coefficient of capacitance turned out increasing the stability of the temperature, decreased $Cr_{2}O_3$ 0.3wt% showed its minimum value 0.59[%/$^{\circ}C$], the maximum value 0.9[%/$^{\circ}C$] with $Cr_{2}O_3$ 3wt%.