• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.6
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• pp.504-510
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• 2002

Recently, thin film capacitors of high dielectric constant and low leakage current are applied to integrated devices. In this study, (Ba, Sr)$TiO_3$ (BST) thin films for low cost were prepared by Sol-Gel method. BST solution was spin-coated on Pt/$SiO_2$/Si substrate at 4,000 rpm for 10 seconds. Coating process was repeated 3 times and then sintered at $700^{\circ}C$ for 30 minutes. Structural and electrical characteristics of each specimen were analyzed by TG-DTA, SEM, fractal phenomenon, voltage-current and dielectric factor. Thickness of BST ceramics thin films are about 2,600~2,800 ${\AA}$ at depositing 3 times. Dielectric constant of thin films was decreased in 1 kHz~1 MHz. Dielectric constant and loss to frequency were 250 and 0.02 in $(Ba_{0.7}Sr_{0.3})TiO_3$ (BST3). Leakage current of BST3 was $10^{-9}\sim10^{-11}$/ A under 3 V.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.336-336
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• 2013

Zinc oxide (ZnO) based transparent oxide semiconductors have been studied due to their high transmittance and electrical conductivity. Pure ZnO have unstable optical and electrical properties at high temperatures but doped ZnO thin films can have stable optical and electrical properties. In this paper, transparent oxide semiconductors of Y-doped ZnO thin films prepared by sol-gel method. The ionic radius of $Y^{3+}$ (0.90 A) is close to that of $Zn^{2+}$ (0.74 A), which makes Y suitable dopant for ZnO thin films. The Sn-doped ZnO thin films were deposited onto quartz substrates with different atomic percentages of dopant which were Y/Zn = 0, 1, 2, 3, 4, and 5 at.%. These thin films were pre-heated at $150^{\circ}C$ for 10 min and then annealed at $500^{\circ}C$ or 1 h. The structural and optical properties of the Y-doped ZnO thin films were investigated using field-emission scanning electronmicroscopy (FE-SEM), X-ray diffraction (XRD), UV-visible spectroscopy, and photoluminescence (PL).

• Journal of the Korean Ceramic Society
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• v.38 no.9
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• pp.777-781
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• 2001

$LiCoO_{2}$ thin films have received attention as cathodes of thin film microbatteries in these days. In this study, $LiCoO_{2}$ thin films are fabricated by a sol-gel spin coating method followed by a post-annealing process. The thermal decomposition behaviour of precursor is investigated by TG/DTA analysis. The change of crystallinity, microstructure and electrochemical properties of final films as the drying temperature changes are also studied by XRD, SEM and galvanostatic charge/discharge cycling test. The relationship between the discharge capacity and the drying temperature are intensively investigated in this work.

• Korean Journal of Materials Research
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• v.4 no.6
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• pp.704-709
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• 1994

The $(LaS)_xCrS_2(x \approx 1.20$) of the incommensurate misfit layer was systhesized from reactant mixture of$La_S_3$,Cr and S at 1273K. Powder X-ray diffration of $(LaS)_xCrS_2(x \approx 1.20$) was indexed as a complex structure consisted with a monoclinic LaS-sublattice, a triclinic $CrS_{2}$-sublattice and their superlattice. The temperature dependence of sublattice dimension was investigated by the X-ray diffraction analysis at low temperature. The magnetic susceptibility of $(LaS)_xCrS_2(x \approx 1.20$) was measured between 77K and room temperature using a Faraday balance method. $(LaS)_xCrS_2(x \approx 1.20$) was paramagnetic on a $\sigma$-H plot at room temperature. The observed effective magnetic moment( p dr) was in fair agreement with the value calculated by spin-only contribution for $Cr^{3+}$ and spin and orbital contribution for $La^{3+}$.

• Journal of Hydrogen and New Energy
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• v.26 no.1
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• pp.15-20
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• 2015

During the liquefaction of hydrogen, the ortho hydrogen is converted into the para form with heat release that evaporates the liquefied hydrogen into the gaseous one backwards. The ortho-para conversion catalysts are usually used during liquefaction to avoid such boil-off. In order to compare and analyze the performance of the ortho-para hydrogen conversion catalysts, in-situ FT-IR device was designed and manufactured to measure the para hydrogen conversion rate in real-time. $LaFeO_3$ and $La_{0.7}Sr_{0.3}Cu_{0.3}Fe_{0.7}O_3$ perovskite catalysts were prepared by the citrate sol-gel method and their spin conversion characteristics from ortho to para hydrogen were investigated by in-situ FTIR spectroscopy at 17K. It was found that the spin conversion was affected by surface area, particle size, and crystallite size of the catalysts. Thus, the $La_{0.7}Sr_{0.3}Cu_{0.3}Fe_{0.7}O_3$ perovskite catalyst that had higher surface area, higher crystallite size, and smaller particle size than $LaFeO_3$ showed the better spin conversion property of 32.3% at 17K in 120min interaction with the perovskite catalysts.

• Journal of the Korean Chemical Society
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• v.33 no.6
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• pp.607-613
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• 1989

The chemical equilibria of Ni(II)-tetraamine (tetraamine = 2,12-dimethyl-3,7,11,17-tetraazabicyclo-11,3,1-heptadeca-1(17),2,11,13,15-pentaene) complex ion in water, acetonitrile, acetone and nitromethane were investigated using spectrophotometric method, respectively. The equilibria between low-spin ($D_{4h}$) and high-spin ($O_h$) structures of Ni-tetraamine complex ion were presented in water, acetonitrile and acetone, but not in nitromethane. The eqilibrium constants, the reaction enthalpies and the reaction entropies were determined from analysis of the temperature dependence of the electronic spectra. The formation of the triplet species ($O_h$) was found to be exothermic. The solvent and electrolyte effects on the equilibrium constants could be explained by the dielectric constants of solvents and the reaction entropies.

• Journal of the Korean Magnetics Society
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• v.16 no.1
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• pp.1-5
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• 2006

The crystallographic properties and cation distribution of oxyspinels ferrite $Co_xFe_{1-x}O_4$ thin films have been explored by X-ray diffraction, vibrating sample magnetometer (VSM), and conversion electron $M\"{o}ssbauer$ spectroscopy (CEMS). Thin films are prepared by sol-gel method. Normal spinel structure is transformed to inverse spinel structure with increasing Co concentration CEMS results indicate that most of $Fe^{3+}$ ions are substituted to $Co^{3+}$ions. Accordingly $Co^{2+}$ ions on octahedral site migrate to tetrahedral site. Magnetic moment is decreased with increasing Co concentration, which means high spin $Fe^{3+}$ ions are replaced by low spin $Co^{3+}$.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.11 no.6
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• pp.252-258
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• 2001

($Ba_{0.7}Sr_{0.3})TiO_3$thin films were perpared on ITO-coated glass substrate by spin-coating method. The sol was sonicated in an ultrasonic bath to promote homogenization and the results were compared with untreated case. By application of the sonication process, crystallization temperatures of films were reduced, microstructers of films were more uniform and denser and the surface roughness of the films was lower from 8.4nm to 5.6nm. In addition, optical transmittances and electrical properties of films prepraed from sonicated sol were superior to those of films from untreated.

• Journal of the Korean Society of Systems Engineering
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• v.2 no.2
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• pp.39-44
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• 2006

With the advent of low cost, miniature and high-g hardened inertial sensors and actuators, many kind of smart munitions are becoming practical such as 1D or 2D TCM, SFM, Range Extended GPS guided munitions and so on. They have more complicated trajectory control algorithm than conventional munitions'. Therefore it is necessary to study the complicated operation algorithm of smart munitions with M&S in advance of developing them. The purpose of this paper is to introduce a practical M&S method to study an operation concept of smart munitions using PRODAS and Matlab.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.12 no.2
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• pp.54-61
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• 1998

Ladder Diagram(LD) is the most extensively used among Programmable Logic Controller(PLC) standard languages for the design of process control system with PLC. But LD has the disadvantages for data processing and maintenance. On the other hand, there is full support for describing sequences so that complete sequential behavior can be easily broken down using a concise graphical language called Sequential Function Chart(SFC). Inspite of those characteristics, SFC is not suitable for describing interlock logic. In this paper, we propose the method for implementing interlock logic by using conventional SFC compiler and verify the effectiveness by applying proposed scheme to the In-Line Spin Coater.Coater.