• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.3
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• pp.65-81
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• 1996

In this study forty-five X-bnd rectangular microstrip patch antennas fed by microstrip line using ${\lambda}$/4 transformer were fabricated on teflon substrates with low high permittivities and varous thickness (substrate thickness : 0.6 ~ 2.4 mm, permittivities : 2.15 ~ 10.0), and effects of permittivity and electrical thickness on antenna characteristics were studied with measured return loss (1/S$_{11}$) and resonant frequencies. When substrate electrical thickness was greater than 0.060 ${\lambda}_{0}$return loss was very good and genrally more than 20 dB, but resonance characteristics was somewhat unstable. The more than 0.088 ${\lambda}_{0}$ the thickness was, the more unstable it was. As a result, in the rest range except 12, 13 GHz we had very good mesured return loss iwth greater than 20 dB, and in the range 7 to 9 GHz resonant frequencies were within $\pm$2 % error, on ${\epsilon}_{r}$=5.0, height = 2.4 mm substrate.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.11
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• pp.932-937
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• 2000

The length extensional vibration mode of a piezoelectric ceramic substrate is used in fabricating the ultra-small size resonators and filters. In general, the three side ratios of the rectangular substrate affect the resonant characteristics of the resonator using its length extensional vibration. In this paper, their relationships are studied. We know that changing the ratio of its length to its width makes possible to change the resonant frequency of the width vibration without degrading the length extensional vibration. And frequency constant for length extensional vibration becomes slightly small as the substrate thickness becomes thin, but it does not change as its length changes. Electro-mechanical coupling factor for length extensional vibration, k$\_$31/ does not change as its length changes within length/width$\geq$4, but it becomes small as its width increases.

• Journal of Surface Science and Engineering
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• v.29 no.5
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• pp.577-584
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• 1996

Silicon oxide films with high hardness and water repellency were prepared by microwave plasma-enhanced CVD using four kind of organosilicon compound-fluoro-alkyl silane mixtures as source gases. An argon gas was used as a carrier gas for fluoro-alkyl silane. The substrate temperatures during deposition were controlled by resistant heating at a constant value between 50 and $300^{\circ}C$. The hardness of the films increased, but the deposition rate and the contact angle for a water drop decreased with increasing substrate temperature. The number of methoxy groups also affected the water repellency and hardness. The deposited films became more inorganic with increasing substrate temperature because of the thermal dissociation of reactants.

• Advances in materials Research
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• v.9 no.1
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• pp.33-48
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• 2020

With the use of differential quadrature method (DQM), forced vibrations and resonance frequency analysis of functionally graded (FG) nano-size beams rested on elastic substrate have been studied utilizing a shear deformation refined beam theory which contains shear deformations influence needless of any correction coefficient. The nano-size beam is exposed to uniformly-type dynamical loads having partial length. The two parameters elastic substrate is consist of linear springs as well as shear coefficient. Gradation of each material property for nano-size beam has been defined in the context of Mori-Tanaka scheme. Governing equations for embedded refined FG nano-size beams exposed to dynamical load have been achieved by utilizing Eringen's nonlocal differential law and Hamilton's rule. Derived equations have solved via DQM based on simply supported-simply supported edge condition. It will be shown that forced vibrations properties and resonance frequency of embedded FG nano-size beam are prominently affected by material gradation, nonlocal field, substrate coefficients and load factors.

• Journal of the Speleological Society of Korea
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• no.76
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• pp.61-66
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• 2006

The present report is the investigation of the effects of the HIP treatment on plasma-sprayed ceramic coating of $Al_2O_3$, $Al_2O_3-SiO_2$ on the metal substrate. These effects were characterized by phase identification, Vickers hardness measurement, and tensile test before and after HIPing.

• Korean Journal of Materials Research
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• v.5 no.6
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• pp.732-742
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• 1995

Effects of the substrate pretreatment on uncleation density of the diamond thin films have been investigated. The film was prepared using the hot-filament CVD reactor with the mixture of methane and hydrogen. The substrate pretreatment was done in three different ways: predeposition of carbon on the substrate, soot on the substrate, and graphite on the substrate. All three cases enhanced the nucleation density of diamond. And the effect was more marked in the first and the second cases than in the third one. In the first case where the substrate was predeposited by the carbon phase, a very smooth and uniform film of diamond could be obtained. Since the bound strength between the substrate and the predeposited carbon phase is relatively weak, separation of the diamond film layer from the substrate was found to be easy.

• Korean Journal of Materials Research
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• v.20 no.8
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• pp.423-428
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• 2010

This study shows the effects of deionized (DI) rinse and oxide HF wet etch processes on silicon substrate during a photolithography process. We found a fail at the wafer center after DI rinse step, called Si pits, during the fabrication of a complementary metal-oxide-semiconductor (CMOS) device. We tried to find out the mechanism of the Si pits by using the silicon wafer on CMOS fabrication and analyzing the effects of the friction charge induced by the DI rinsing. The key parameters of this experiment were revolution per minute (rpm) and time. An incubation time of above 10 sec was observed for the formation of Si pits and the rinsing time was more effective than rpm on the formation of the Si pits. The formation mechanism of the Si pits and optimized rinsing process parameters were investigated by measuring the charging level using a plasma density monitor. The DI rinse could affect the oxide substrate by a friction charging phenomenon on the photolithography process. Si pits were found to be formed on the micro structural defective site on the Si substrate under acceleration by developed and accumulated charges during DI rinsing. The optimum process conditions of DI rinse time and rpm could be established through a systematic study of various rinsing conditions.

• Journal of Korean Society of Water and Wastewater
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• v.35 no.3
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• pp.197-204
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• 2021

In MBR, extracellular polymeric substance (EPS) is known as an important factor of fouling; soluble EPS (sEPS) affects internal contamination of membrane, and bound EPS (bEPS) affects the formation of the cake layer. The production of EPS changes according to the composition of influent, which affects fouling characteristics. Therefore, in this study, the effects of the F/M ratio on the sEPS concentration, bEPS content, and fouling were evaluated. The effects of F/M ratio on the amount and composition of EPS were confirmed by setting conditions that were very low or higher than the general F/M ratio of MBR, and the fouling occurrence characteristics were evaluated by filtration resistance distribution. As a result, it was found that the sEPS increased significantly with the increase of the F/M ratio. When the substrate was depleted, bEPS content decreased because bEPS was hydrolyzed into BAP and seemed to be used as a substrate. In contrast, when the substrate is sufficient, UAP (utilization-associated products) was rapidly generated in proportion with the consumption of the substrate. UAP has a relatively higher Protein/Carbohydrate ratio (P/C ratio) than BAP, and this means, it has a higher adhesive force to the membrane surface. As a result, UAP seems like causing fouling rather than BAP (biomass-associated products). Therefore, R_f (Resistance of internal contamination) increased rapidly with the increase of UAP, and R_c (Resistance of cake layer) increased with the accumulation of bEPS in proportion, and as a result, the fouling interval was shortened. According to this study, a high F/M ratio leads to an increment in UAP generation and accumulation of bEPS, and by these UAP and bEPS, membrane fouling is promoted.

• Journal of Hydrogen and New Energy
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• v.28 no.5
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• pp.440-446
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• 2017

This study was aimed at evaluating the effects of carbohydrate, protein and lipid content of substrate on hydrogen yields and microbial communities. The hydrogen yields were linearly correlated to carbohydrate content of substrates while others (content of proteins and lipids) did not make a significant contribution. The chemical composition of substrates produced effects on the final products of anaerobic hydrogen fermentation. Acetate and butyrate were the main fermentation products, with their concentration proving to correlate with carbohydrate and protein content of substrates. The result of microbial community analysis revealed that the relative abundances of Clostridium butyricum increased and Clostridium perfringens decreased as the carbohydrate content increased.

• Korean Journal of Materials Research
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• v.9 no.5
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• pp.509-514
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• 1999

Interest in the integrated capacitors, which make it possible to reduce the size of and to obtain improved electrical performance of an electronic system, is expanding. In this study, $Ta_2$O\ulcorner thin film capacitors for MCM integrated capacitors were fabricated on a Upilex-S polymer film by DC magnetron reactive sputtering and the effects of low temperature annealing at various atmospheres and substrate surface morphology on the capacitor characteristics were discussed. The low temperature($150^{\circ}C$) annealing produced improved capacitor yield irrespective of the annealing at mosphere. But the leakage current of the $O_2$-annealed film was larger than that of any other films. This is presumably mosphere. But the leakage current of the $O_2$-annealed film was larger than that of any other films. This is presumably due to the change of the $Ta_2$O\ulcorner film surface by oxygen, which was explained by conduction mechanism study. Leakage current and breakdown field strength of the capacitors fabricated on the Upilex-S film were 7.27$\times$10\ulcornerA/$\textrm{cm}^2$ and 1.0 MV/cm respectively. These capacitor characteristics were inferior to those of the capacitors fabricated on the Si substrate but enough to be used for decoupling capacitors in multilayer package. Roughness Analysis of each layer by AFM demonstrated that the properties of the capacitors fabricated on the polymer film were affected by the surface morphology of the substrate. This substrate effect could be classified into two factors. One is the surface morphology of the polymer film and the other is the surface morphology of the metal bottom electrode determined by the deposition process. Therefore, the control of the two factors is important to obtain improved electrical of capacitors deposited on a polymer film.