• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.7
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• pp.589-594
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• 2009

We have studied electro-optic characteristics as a function of passivation thickness existing between common electrode and pixel electrodes in the fringe-field switching (FFS) mode using the LC with positive dielectric anisotropy. A steep increase in the transmission is observed with increase in the passivation layer from $0.29{\mu}m$ to $1.09{\mu}m$ and thereafter it almost saturates over the $1.09{\mu}m$ of passivation layer. This saturation is mainly associated with correlation between transmittance at the center region of pixel electrode and at the center region between pixel electrodes. From the results, optimal thickness of passivation layer can be defined.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.11
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• pp.725-728
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• 2016

We investigated the characterizations of carbon films fabricated by dual magnetron sputtering under various film thickness for the electrodes in TCO-less DSSC (dye-sensitized solar cells). Carbon films prepared at various conditions were exhibited smooth and uniform surfaces without defects. Also, the rms surface roughness of carbon films was decreased from 2.25 nm to 1.0 nm with the increase of film thickness. The sheet resistance as the electrical properties are improved from $11.2{\times}10^{-3}$ to $2.28{\times}10^{-3}$ with the increase of film thickness. In the results, the performance of TCO-less DSSC critically depended on the film thickness of working electrodes, indicating the conductivity of carbon films.

• Progress in Superconductivity and Cryogenics
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• v.15 no.2
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• pp.9-11
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• 2013

We have investigated the effect of thickness of the MgB2 film on the grain growth direction as well as on their superconducting properties. $MgB_2$ films of various thicknesses were fabricated on c-cut $Al_2O_3$ substrates at a temperature of $540^{\circ}C$ by using hybrid physical-chemical vapor deposition (HPCVD) technique. The superconducting transition temperature ($T_c$) was found to increase with increase in the thickness of the $MgB_2$ film. X-ray diffraction analysis revealed that the orientation of grains changed from c-axis to a-axis upon increasing the thickness of the $MgB_2$ film from 0.6 to 2.0 ${\mu}m$. $MgB_2$ grains of various orientations were observed in the microstructures of the films examined by scanning electron microscopy. It is observed that at high magnetic fields the 2.0-${\mu}m$-thick film exhibit considerably larger critical current density ($J_c$) as compared to 0.6-${\mu}m$-thick film. The results are discussed in terms of an intrinsic-pinning in $MgB_2$ similarly as intrinsic-pinning occurring in high-Tc cuprate superconductors with layered structure.

• Journal of the Korean institute of surface engineering
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• v.1 no.1
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• pp.14.1-18
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• 1967

The characteristics of sulfuric acid anodized layer was studied under various Conbitions, acid concentration : 5-20%, temperature : 5-25$^{\circ}C$, bath voltate : 16 volts , bath agitain : mech agitation : mechanical . The Al+++ ion increase in anodizing baty, the film thickness under microscope, the comparative porosity and the thickness were determined. It was found that film thickness and the porosithy which are the main factors of determining andoized layet quality, rule the corrosing and abrasiion tesistance of the film, and that the porosity is increasing in the outerlayer. The formation mechanism was assumed as follows : The film thickness -increase is due to OH_ ion diffusion into compact non-conductive layer and Al+ + OH_ \longrightarrowAl(OH), Al(OH)+ + OH_ \longrightarrowAl(OH)+$_2$ , Al(OH)+$_2$ + OH_ \longrightarrowAl(OH)$_3$., the strong adhesion force is alse due to Al(OH) or Al(OH)$_2$ in transtion layer. And the pore-nucleation is produced by volume change between Al and Al$_2$O$_3$ and activated H$_2$O gas created by large reaction heat of Al+(x) +OH_ \longrightarrowAl(OH)x.

• Journal of the Korean institute of surface engineering
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• v.32 no.6
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• pp.695-702
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• 1999

We have explored the factors affecting the resistivity of Cu (Mg) alloy, which was prepared by sputtering. The results show that the resistivity is a function of Mg content, annealing temperature, annealing time, and Cu-alloy thickness. Addition of Mg to copper increases the resistivity through solute scattering. In addition, increasing Mg content promotes the interfacial reaction between Mg and SiO$_2$ to produce the free silicon and the generated free silicon dissolves into copper, resulting in a significant increase of resistivity. Furthermore, increasing oxidation temperature rapidly decreases the resistivity at the initial stage of oxidation and then continues to increase the resistivity to the saturation value with increasing oxidation time. The saturation value depends on the residual Mg content and the thickness of the alloy. TEM and AES analyses reveal that dense, uniform MgO grows to the limiting thickness of about $150\AA$. However, interfacial MgO does not show the limiting thickness, instead continues to grow until Mg is completely exhausted. From these facts, we proposed the maximum available Mg content needed to from the dense MgO on the surface and suppress the excessive interfacial reaction.

• Journal of the Semiconductor & Display Technology
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• v.19 no.3
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• pp.30-35
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• 2020

A microlens has been fabricated by various methods such as a thermal reflow, hot embossing, diamond milling, etc. However, these methods require a relatively complex process to control the microlens shape. In this work, we report on a simple and cost-effective method to fabricate a cylindrical microlens (CML), which can diffuse light widely. We have employed a slot-die head with the dual plate (a meniscus guide with a protruded μ-tip and a shim with a slit channel) for coating of a narrow stripe using poly(methyl methacrylate) (PMMA). We have shown that the higher the coating gap, the lower the maximum coating speed, which causes an increase in the stripe width and thickness. The coated PMMA stripe has the concave shape. To make it in the shape of a convex microlens, we have applied the thermal reflow method. When the stripe thickness is small, however, its effect is negligible. To increase the stripe thickness, we have increased the number of repeated coating. With this scheme, we have fabricated the CML with the width of 223 ㎛ and the thickness of 7.3 ㎛. Finally, we have demonstrated experimentally that the CML can diffuse light widely, a feature demanded for light extraction efficiency of organic light-emitting diodes (OLEDs) and suppression of moiré patterns in displays.

• Journal of the Korean Ceramic Society
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• v.49 no.6
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• pp.642-647
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• 2012

$TiO_2$ thin films for a pulse power capacitor were deposited by RF magnetron sputtering. The effects of the deposition gas ratio and thickness on the crystallization and electrical properties of the $TiO_2$ films were investigated. The crystal structure of $TiO_2$ films deposited on Si substrates at room temperature changed to the anatase from the rutile phase with an increase in the oxygen partial pressure. Also, the crystallinity of the $TiO_2$ films was enhanced with an increase in the thickness of the films. However, $TiO_2$ films deposited on a PET substrate showed an amorphous structure, unlike those deposited on a Si substrate. An X-ray photoelectron spectroscopy(XPS) analysis revealed the formation of chemically stable $TiO_2$ films. The dielectric constant of the $TiO_2$ films as a function of the frequency was significantly changed with the thickness of the films. The films showed a dielectric constant of 100~110 at 1 kHz. However, the dissipation factors of the films were relatively high. Films with a thickness of about 1000nm showed a breakdown strength that exceeded 1000 kV/cm.

• Journal of the Korean Society of Safety
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• v.13 no.3
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• pp.11-23
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• 1998

In this study, collapse test of thin-walled structure is performed under axially quasi-static and impact load in collapse characteristic to develop the optimum structural member for a light-oriented automobile. Furthermore, the energy-absorbing capacity is observed according to the variety of configuration(circular, square), aspect ratio in aluminum specimen to obtain basic data for the improved member of vehicle. In both quasi-static and impact collapse test, Al circular specimens collapse, in general, with axisymmetric mode in case of thin thickness while collapse with non-axisynmetric mode according to the thickness increase. For Al rectangular specimens, they collapse with axisymmetric mode in case of thin thickness, with mixed collapse mode according to the increase of thickness. In terms of initial max. load, Al square specimen turns out the best member among specimens, and then Al square, circular and circular with large scaling ratio, respectively. In case of quasi-static compression test, the absorbed energy per unit volume and mass shows higher in Al circular specimen, and then Al square, circular with large scaling ratio, respectively, according to shape ratio the absorbed energy per unit volume and mass in case of max. impact compression load is higher than that of static load. But the absorbed energy per unit volume and mass shows that Al circular specimen is the best member. Especially, unlike max. compression loan, the absorbed energy per unit volume and mass in impact test turns out the low value.

• Nuclear Engineering and Technology
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• v.55 no.6
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• pp.2325-2334
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• 2023

To study the lubrication performance of tilting-pad thrust bearing (TPTBs) during start-up in nuclear pump, a hydrodynamic lubrication model of TPTBs was established based on the computational fluid dynamics (CFD) method and the fluid-structure interaction (FSI) technique. Further, a mesh motion algorithm for the transient calculation of thrust bearings was developed based on the user defined function (UDF). The result demonstrated that minimum film thickness increases first and then decreases with the rotational speed under start-up condition. The influence of pad tilt on minimum film thickness is greater than that of collar movement at low speed, and the establishment of dynamic pressure mainly depends on pad tilt and minimum film thickness increases. As the increase of rotational speed, the influence of pad tilt was abated, where the influence of the moving of the collar dominated gradually, and minimum film thickness decreases. For TPTBs, the circumferential angle of the pad is always greater than the radial angle. When the rotational speed is constant, the change rate of radial angle is greater than that of circumferential angle with the increase of loading forces. This study can provide reference for improving bearing wear resistance.

• Transactions of the Korean Society of Mechanical Engineers
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• v.7 no.1
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• pp.19-27
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• 1983

This paper deals with hardness and wear characteristics of ion-nitrided metal, and with ion-nitride processing which is concerned with the effects of added carbon content in gas atmosphere. A small optimal amount of carbon content in gas atmosphere increase compound layer thickness, as well as to increase diffusion layer thickness and hardness, and reduces wear rate when the applied wear load is small. It is found in the analysis that under small applied wear load, the critical depth where voids and cracks may be created and propagated is located at the compound layer, so that the abrasive wear where hardness is an important factor, is created and the existence of compound layer reduces the amount of wear. When the load becomes large, the critical depth is located below nucleation and propagation, is created and the existence of compound layer increase wear rate.