• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.2
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• pp.67-72
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• 2004

The microwave dielectric properties and microstructure of the (1-x)$Mg_4Ta_2O_{9-x}TiO_2$(X=0, 0.3, 0.4) ceramic were, investigated. The specimens were prepared by the conventional mixed oxide method with sintering temperature of $1350^{\circ}C$∼$1425^{\circ}C$. According to the XRD patterns, the (1-x)$Mg_4Ta_2O_{9-x}TiO_2$(X=0, 0.3, 0.4) ceramics have the $Mg_4Ta_2O_{9}$ phase(hexagonal). The dielectric constant($\varepsilon$$_{\gamma}$) and density increased with sintering temperature and mole fraction of x. To improve the quality factor and the temperature coefficient of resonant frequency, TiO$_2$($\varepsilon_{r}$=100, $Q{\times}f_{r}$=40,000GHz, $\tau$$_{f}$=＋450 ppm/$^{\circ}C$) was added in $Mg_4Ta_2O_{9}$ ceramics. In the case of the $0.7Mg_4Ta_2O_{9}$-$0.3TiO_2$ and the $0.6Mg_4Ta_2O_{9}$-$0.4TiO_2$ceramics sintered at $1400^{\circ}C$ for 5hr., the microwave dielectric properties were $\varepsilon$$_{\gamma}$=11.72, $Q{\times}f_{r}$=126,419GHz, $\tau_{f}$=-31.82 ppm/$^{\circ}C$ and $\varepsilon_{r}$=12.19, $Q{\times}f_{r}$=109,411GHZ, $\tau$$_{f}$= -17.21 ppm/$^{\circ}C$, respectively.

• Journal of the Korean Magnetics Society
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• v.11 no.5
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• pp.222-225
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• 2001

The planar type inductors have a good potential for the application of miniaturized low power DC-DC converters. For those high quality application, the reduction of coil loss and also magnetic films which have good high frequency properties are required. Fabricated inductor was consisted of FeTaN/Ti magnetic film and electroplated Cu coil thickness of 100$\mu\textrm{m}$ and $SiO_2$ as a insulating layer. The inductor was designed double rectangular spiral shape for magnetic field highly confining within the device. The measured value of inductance and resistance were 980 nH and 1.7 $\Omega$ at 1 MHz as operating frequency of device. The Q factor is 3.55 at 1 MHz.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.371-373
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• 1998

The SmBa$_2$Cu$_3$O$\sub$x/ single crystals were used as seeds to induced YBCO growth in MTG process. As the result, the large bulk oriented YBCO superconductors were prepared with dimension of plane 21mm and 32mm in diameter and 10mm in height. The typical Jc value of the sample is 6.5${\times}$10$^4$A/$\textrm{cm}^2$ and its flux float force is 4.6N/$\textrm{cm}^2$. The oxygen absorption in large bulk textured YBCO samples in pure oxygen was studied at several constant temperatures. It can be divided into two steps: a chemical reaction step and a diffusion step.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.491-493
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• 1998

The SmBa$_2$Cu$_3$O$\sub$x/ single crystals were used as seeds to induced YBCO growth in MTG process. As the result, the large bulk oriented YBCO superconductors were prepared with dimension of plane 21mm and 32mm in diameter and 10mm in height. The typical Jc value of the sample is 6.5${\times}$10$^4$A/$\textrm{cm}^2$ and its flux float force is 4.6N/$\textrm{cm}^2$. The oxygen absorption in large bulk textured YBCO samples in pure oxygen was studied at several constant temperatures. It can be divided into two steps: a chemical reaction step and a diffusion step.

• Korean Journal of Optics and Photonics
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• v.10 no.2
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• pp.152-156
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• 1999

We have developed the pulse-width variable Quenched Dye Laser (QDL). QDL consisted of the dye cell of 5 mm length containing a $2.5{\times}10^{-3}$[mol/l] solution of Rhodamine 6G and the cylindrical lens focal length of 150 mm and quenching mirror. QDL system was pumped by s XeCl excimer laser with 150 mJ pulse energy in a 20 ns pulse at 1 Hz repetition rate. Pulse-width of QDL was measured by a noncollinear intensity autocorrelator. The focused thckness was measured by changing the position of the focusing cylindrical lens. Pulse-width of QDL as a function of the focused thickness (273.0${\mu}{\textrm}{m}$~845.0${\mu}{\textrm}{m}$) varied continuously from 86 ps to 201 ps.