• Journal of the Korean Vacuum Society
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• v.5 no.3
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• pp.223-228
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• 1996

$SiO_2$ insulator layers on InSb have been prepared by remote PECVD system a low temperature below $200^{\circ}C$. The effects of deposition pressure, temperature, and gas flow ratio on the physical and electrical characteristics of the $SiO_2$ were studied. The InSb MIS device using $SiO_2$ was fabricated and measured its current-voltage and capacitance-voltage characteritance-voltage charateristics at 77K. The films evaluated Auger electron spectroscopy showed that composition atoms were distributed uniformaly throughout the oxide film and the outdiffusion of substrate atoms into the oxide were few. The leakage current density of the MIS device was about 6.26nA/$\textrm{cm}^2$ at 0.75MV/cm , and the breakdown voltage was about 1MV/cm. The interface-stage density at mid-bandgap extracted from 1MHz C-V measurement was $54\times 10^{11}\textrm{cm}^2-2V^{-1}$.

• Journal of Conservation Science
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• v.2 no.2 s.2
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• pp.25-30
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• 1993

Materials (refractory, stone) of iron making furnace excavated from Kalcheon were investigated by the scanning electron microscopy(SEM) with an energy dispersive X-ray analysis (EDAX), X-ray fluorescence(XRF), and X-ray diffraction(XRD). Chemical composition of the refractory materials were $SiO_2(68.74\%),\;Al_2O_3(18.40\%),\;CaO(0.42\%),\;MgO(1.04\%)\;and\;K_2O(2.26\%)$ in weight ratio, which were the typical components presented in common clay. The results of chemical analysis for the stone and the glaze coated, alkali ion(K, Na, Ca) components of the glaze contained high concentration than that the stone. It was suggested that this change had a close relationship with the kinds of fuels used.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1991.10a
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• pp.20-23
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• 1991

In this study, 0.05Pb(Mn$\_$1/3/Nb$\_$2/3/)O$_3$+ 0.95Pb(Zr/Ti)O$_3$+x[wt%]Cr$_2$O$_3$piezoelectric ceramics were fabricated by Hot-press method, and its structural, dielectrical, piezoelectrical properties, temperature stability and aging characteristics were investigated. Among the MPB and tetragonal compositions, the specimens with 0.2, 0.3 and 0.4 [wt%] Cr$_2$O$_3$ additive amount had the poisson ratio more than 1/3. At tetragonal phase, the aging was small, and the temperature stability was improved by Cr addition. The specimen most suitable to the HF device substrate was the one with the composition of 47/53 (Zr/Ti) an 0.4 [wt%] Cr$_2$O$_3$addition.

• Journal of the Korean Ceramic Society
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• v.23 no.1
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• pp.27-32
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• 1986

This study is aimed at synthsizing high dielectric material (Ba, Sr)$TiO_3$ through direct wet process. Pure and ultra fine particle of (Ba, Sr)$TiO_3$ Powder was synthesized from $BaCl_2$ $SrCl_2$ and TiCl4 aqeous solution at KOH Solution in the $N_2$ gas atmosphere. $BaCl_2$ $SrCl_2$ and TiCl4 were Mixed with the mole ratio of 1:9, 3:7:10, 5:5:10, 7:3:10, 9:1:10 and sythesized at 4$0^{\circ}C$~9$0^{\circ}C$ for 10min~15hrs. The particle size particle shape crystallinity and synthesis condition of (Ba, Sr)$TiO_3$ powder with the variation of temperature and reaction time in the aqueous solution studied by the exprimental instruments of DTA. TGA, X-ray diffratometer SEM.

• Proceedings of the KIEE Conference
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• 1997.07d
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• pp.1301-1303
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• 1997

This study was performed to investigate the deposition mechanism of $SiO_2$ by ArF excimer Laser(193nm) CVD with $Si_2H_6$ and $N_2O$ gas mixture and evaluate Laser CVD quantitatively by modeling. In this study, new model of $SiO_2$ deposition process by Laser CVD is introduced and deposition rates are simulated by computer with the basis on this modeling. And simulation results are compared with experimental results measured at various conditions such as reaction gas ratio, chamber pressure, substrate temperature and laser beam intensity.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.113-117
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• 1999

SrBi$_2$Ta$_2$$O_{9}$ (SBT) thin films were fabricatcd with different Sr/Bi ratios by MOD. SBT thin films of thickness 2500$\AA$ deposited on Pt/Ti/SiO$_2$/Si were crystallized at $700^{\circ}C$ ~85$0^{\circ}C$ using RTA method. As the Sr/Bi ratio was decreased, dielectric constant and remanent polarization were increased. SrBi$_2$Ta$_2$$O_{9}$ showed a maximum dielectric constant value of $\varepsilon$$_{r}$= 268, and maximum remanent polarization (2Pr) of ~9.86 $\mu$C/$\textrm{cm}^2$ when annealed at 8$0^{\circ}C$ for 8 min.min.n.

• Applied Chemistry for Engineering
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• v.16 no.5
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• pp.641-647
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• 2005

The partial oxidation of methane is one of important processes for hydrogen production. As a membrane reactor, palladium-silver (Pd-Ag) alloy membrane prepared by electroless plating technique was employed for partial oxidation of methane. The experimental variables were reaction temperature, $O_2/CH_4$ mole ratio, $CH_4$ feed rate, and $N_2$ sweep gas flow rate. The methane conversions increased with the reaction temperatures in the range of 350 to $730^{\circ}C$. The highest methane conversion and CO selectivity were obtained at the condition of $O_2/CH_4$ mole ratio of 0.5 and $730^{\circ}C$ using commercially available nickel/alumina catalyst. The Pd-Ag membrane reactor showed higher methane conversions, 10~40% higher, compared to those in a traditional reactor.

• Resources Recycling
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• v.7 no.5
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• pp.46-51
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• 1998

A study has been on the recovery of nitric acid and valuable metals such as Fe, Cu, Sn, Pb, from spent nitric etching solutions. The effects of extractant of extractant type, concentrations, phase raios and selectivity from Fe, Cu, Sn, Pb on nitric acid extraction were studied. The results showed that TBP as an extractant for recovering of nitric acid was more effective than Alamine336, and the optimal concentration of TBP was found to be 60~70% of organic phase. Also, the nitric acid were only extracted by TBP from the spent etching solutions and the heavy metals such as Fe, Cu, Sn, Pb were not extracted above 0.1N nitric acid in spent etching solutions, From the analysis of McCabe-Thiele diagram, the extraction of 95% nitric acid is attained at a ratio of O/A=3 with five stages by 60% TBP and the stripping of 98% nitric acid from 80 g/l nitric acid in organic phase is attained at a ratio of O/A=1 with four stages by distilled water.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.306.2-306.2
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• 2016

Niobium oxide thin films were synthesized by reactive rf magnetron sputtering. The target was metallic niobium with 2 inch in diameter and the substrate was n-type Si wafer. To control the surface properties of the films, Nb oxide thin films were obtained at various mixing ratios of argon and oxygen gases. Nb oxide thin films were analyzed with alpha step, scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The result of alpha step showed that the thickness of Nb oxide thin films were decreased with increasing the oxygen gas ratios. SEM images showed that the granular morphology was formed at 0% of oxygen gas ratio and then disappeared at 20 and 75% of oxygen gas ratio. The amorphous Nb oxide was observed by XRD at all films. The oxidation state of Nb and O were studied with high resolution Ni 2p and O 1s XPS spectra. And the change in the chemical environment of Nb oxide thin films was investigated by XPS with Ar+ sputtering.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.11
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• pp.2942-2953
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• 1996

This paper studies the effect of intersymbol interference due to sampling-time jitter on the worst-case bit error probability in a digital modultation over an additive white Gaussian noise channel, with the squared-root raised-cosine filters in the transmitter and the receiver. It derives approximation formulas using the Taylor series approximations. the principal results of this paper is the relationship between the worst-casse bit error probability, the degree of jitter, the roll factor of the raised cosine filter, and other quantities. Numerical results show, as expected, that the intersymbol interference decreases as the roll-off factor increases and the jitter decreases. They also show that the approximation formulas are accurate for smally intersymbol interference, i.e., for large roll-noise ratio $E_{b/}$ $N_{0}$.leq.7 dB and begin to lose accuracy for larger signal-to-noise ratio.o.o.