• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.1
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• pp.29-34
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• 2009

PLZT thin films were deposited on platinized silicon (Pt/$TiSiO_2$/Si) substrate by RF magnetron sputtering. A $TiO_2$ buffer layer was fabricated, prior to deposition of PLZT films. the layer was strongly affected the crystallographic orientation of the PLZT films. X-ray diffraction was performed on the films to study the crystallization of the films as various substrate temperatures (Ts). According to increasing Ts, preferred orientation of films was changed (110) plane to (111) plane. The ferroelectric, dielectric and electrical properties of the films were also investigated in detail as increased substrate temperatures. The PLZT films deposited at $400^{\circ}C$ showed good ferroelectric properties with the remnant polarization of $15.8{\mu}C/cm^2$ and leakage current of $5.4{\times}10^{-9}\;A/cm^2$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.34 no.1
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• pp.39-43
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• 2021

In the case of ZnO:Al thin films, it is the best material that can replace ITO that is mainly used as a transparent electrode in electronic devices such as solar cells and flat-panel displays. In this study, ZnO:Al films were fabricated by using the RF dual magnetron sputtering method at various substrate temperatures. As the substrate temperature increased, the crystallinity of the ZnO:Al thin films was improved, and the electrical conductivity and electrical properties of the thin film improved owing to the increase in grain size. In addition, the surface roughness of the ZnO:Al thin films increased due to changes in the surface and density of the thin films. Moreover, the substrate temperature increased the density of thin films and improved their transmittance. To be applied to solar cells and other several electronic devices in the future, the hardness and adhesion properties of the thin film improve as the substrate temperature increases.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.6
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• pp.50-59
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• 2022

The design of the substrate significantly affects the thermal history and the residual stress formation in the vicinity of a repaired region by a directed energy deposition (DED) process. The occurrence of defects in the repaired region depends on the thermal history and residual stress formation. The objective of this study was to investigate the influence of the inclined angle and depth of the substrate on the thermal and residual stress characteristics in the vicinity of a repaired region by a DED process through two-dimensional finite element analyses (FEAs). The temperature and residual stress distributions in the vicinity of the repaired region were predicted according to the combination of the inclined angle and depth of the substrate. The effects of the inclined angle and depth on the depth of the heat affected zone and the maximum value of the residual stress were examined. A proper combination of the inclined angle and depth of the substrate was estimated to decrease the residual stress in the vicinity of the repaired region.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.93-93
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• 2016

Large scale integrated circuits (LSIs) has been improved by the shrinkage of the circuit dimensions. The smaller chip sizes and increase in circuit density require the miniaturization of the line-width and space between metal interconnections. Therefore, an extreme precise control of the critical dimension and pattern profile is necessary to fabricate next generation nano-electronics devices. The pattern profile control of plasma etching with an accuracy of sub-nanometer must be achieved. To realize the etching process which achieves the problem, understanding of the etching mechanism and precise control of the process based on the real-time monitoring of internal plasma parameters such as etching species density, surface temperature of substrate, etc. are very important. For instance, it is known that the etched profiles of organic low dielectric (low-k) films are sensitive to the substrate temperature and density ratio of H and N atoms in the H2/N2 plasma [1]. In this study, we introduced a feedback control of actual substrate temperature and radical density ratio monitored in real time. And then the dependence of etch rates and profiles of organic films have been evaluated based on the substrate temperatures. In this study, organic low-k films were etched by a dual frequency capacitively coupled plasma employing the mixture of H2/N2 gases. A 100-MHz power was supplied to an upper electrode for plasma generation. The Si substrate was electrostatically chucked to a lower electrode biased by supplying a 2-MHz power. To investigate the effects of H and N radical on the etching profile of organic low-k films, absolute H and N atom densities were measured by vacuum ultraviolet absorption spectroscopy [2]. Moreover, using the optical fiber-type low-coherence interferometer [3], substrate temperature has been measured in real time during etching process. From the measurement results, the temperature raised rapidly just after plasma ignition and was gradually saturated. The temporal change of substrate temperature is a crucial issue to control of surface reactions of reactive species. Therefore, by the intervals of on-off of the plasma discharge, the substrate temperature was maintained within ${\pm}1.5^{\circ}C$ from the set value. As a result, the temperatures were kept within $3^{\circ}C$ during the etching process. Then, we etched organic films with line-and-space pattern using this system. The cross-sections of the organic films etched for 50 s with the substrate temperatures at $20^{\circ}C$ and $100^{\circ}C$ were observed by SEM. From the results, they were different in the sidewall profile. It suggests that the reactions on the sidewalls changed according to the substrate temperature. The precise substrate temperature control method with real-time temperature monitoring and intermittent plasma generation was suggested to contribute on realization of fine pattern etching.

• Korean Journal of Materials Research
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• v.12 no.11
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• pp.856-859
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• 2002

To investigate effects of heat treatments including grain size control in substrate aluminum on nanopore arrays in anodic alumina template, aluminum was heat treated at $500^{\circ}C$ for 1h. The heat treated aluminum was anodized by two successive anodization processes in oxalic solution and the nanopore arrays in anodic alumina layer were studied using TEM and FE-SEM. The highly ordered porous alumina templates with 110 nm interpore distance and 40 nm pore diameter have been observed and the pore array of the anodic alumina has a uniform and closely-packed honeycomb structure. In the case of alumina template obtained from heat treated aluminum substrate, the well- ordered nanopore region in anodic alumina increased and became more homogeneous compared with that from non-heattreated one.

• Journal of Environmental Science International
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• v.21 no.1
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• pp.105-111
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• 2012

The effects of substrate size on the growth of microphytobenthos Achnanthes sp., Amphora sp., Navicula sp. and Nitzschia sp. were examined using glass beads in order for phytoremediation in the benthic layer of coastal waters. The glass beads used in this study were 0.09~0.15 mm (G.B 1), 0.25~0.50 mm (G.B 2), 0.75~1.00 mm (G.B 3) and 1.25~1.65 mm (G.B 4). No addition of glass bead used as control. The specific growth rate and maximum cell density of four microphytobenthos species were increasing with decreasing size of glass beads. Moreover, the control experiment without added attachment substrates showed the lowest specific growth rate and maximum cell density. Therefore, the suitable attachment substrates for mass culture of microphytobenthos seems to be important in order for phytoremediation using microphytobenthos.

• Journal of Sensor Science and Technology
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• v.13 no.4
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• pp.282-286
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• 2004

${\alpha}-Fe_{2}O_{3}$ films were prepared by ultrasonic spray pyrolysis (USP) on $SiO_{2}$ coated Si wafers using iron acetylacetonate as an iron precursor. The crystallographic properties and surface morphologies of the films were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. X-ray photoelectron spectroscopy (XPS) was carried out to determine the Fe oxidation states. In order to observe stability of the films to temperature, the resistance variation of the films with an ambient temperature was measured. The effects of substrate temperature on the structural and electrical properties of the ${\alpha}-Fe_{2}O_{3}$ films were studied. The films were densified from the substrate temperature of $350^{\circ}C$. The grain size of the films grown at $400^{\circ}C$ was shown to be increased abruptly comparing with that of $350^{\circ}C$. The films showed a low resistance variation between the ambient temperature of $300^{\circ}C$ and $350^{\circ}C$.

• Korean Journal of Microbiology
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• v.10 no.4
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• pp.167-174
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• 1972

Effects of 13 organic compounds including glucose, fructose, xylose, glutamate, succinate, malate, glycine, lactate, acetate, pyruvate, citrate, formate and cis-aconitate on the oxidation of thiosulfate and the availability of these compounds as the substrate for the respiration by Thiobacillus ocncretivorus, which is known to be an obligated autotroph, were studied. Malate nad glycine at 0.5 per cent concentration nearly doubled the thiosulfate oxidation compared to the control. No other organic substances enhanced the thiosulfate oxidation compared to the control. No other organic substances enhanced the thiosulfate oxidation. Moreover, some 30 to 40 per cent decrease was recorded by fructose, sulfate-salts medium, some 30 to 40 per cent decrease was recorded by fructose, citrate, xylose, malate, flucose, glutamate and succinate. No respiration could occur when formate and pyruvate were supplied as the substrate for respiration. But it was obvious that flucose, fructose, xylose, glutamate, malate, citrate and succinate could be used as the substrate for respiration to some extent, regarding the fact that some increase in respiration rates could be recorded compared to the result from the salts medium, where neither thiosulfate nor orgnic compounds were added. Thus, it was postulated that this organism could possibly be converted into mixotroph or hetrotroph if appropriate conditions could be prepared.

• Transactions on Electrical and Electronic Materials
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• v.14 no.5
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• pp.225-230
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• 2013

This paper presents a novel shunt radio frequency microelectromechanical system switch on a quartz substrate with stiff ribs around the membrane. The buckling effects in the switch membrane and stiction problem are the primary concerns with RF MEMS switches. These effects can be reduced by the proposed design approach due to the stiffness of the ribs around the membrane. A lower mass of the beam and a reduction in the squeeze film damping is achieved due to the slots and holes in the membrane, which further aid in attaining high switching speeds. The proposed switch is optimized to operate in the k-band, which results in a high isolation of -40 dB and low insertion loss of -0.047 dB at 21 GHz, with a low actuation voltage of only 14.6 V needed for the operation the switch. The membrane does not bend with this membrane design approach. Finite element modeling is used to analyze the stress and pull-in voltage.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.5
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• pp.684-689
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• 2006

The present study examined the effects of Tween 80 on the attachment and hydrolytic activity of a cellulase enzyme against ball-milled cellulose (BMC), using the whole component (native CBH I) and the catalysis module (core CBH I) of carbohydrolase I purified from Trichoderma viride (Meicelase, Meiji Seika, Tokyo, Japan). The effects were evaluated as protein concentrations in the supernatant after mixing enzyme and substrate with Tween 80 at room temperature. Tween 80 decreased the adsorption of native CBH I and core CBH I onto BMC (p<0.001) and increased the amount of reducing sugars released from BMC by native CBH I (p<0.001). However, Tween 80 did not enhance the hydrolytic activity of core CBH I. Observations using SEM revealed that Tween 80 caused cellulose filter paper to swell and enhanced surface cracks and filaments caused by native CBH I but not by core CBH I. These results suggested that Tween 80 decreases enzyme adsorption to its substrate but enhances enzymatic activity.