• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 춘계학술대회 논문집 디스플레이 광소자분야
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• pp.81-83
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• 2003

We have investigated the generation of pretilt angle for a nematic liquid crystal (NLC) alignment with rubbing alignment method on polyimide surfaces using thin plastic substrates. It was found that monodomain alignment of LNC is obtained with rubbing alignment method on polyimide surfaces using thin plastic substrates. The generated NLC pretilt angles are about $3^{\circ}$ by the rubbing alignment method on thin plastic substrates, However, the pretilt angle measured at about $1.7^{\circ}$ lower on the glass substrate than by thin plastic substrate. It is considered that this alignment may be attributed to roughness of micro groove substrate. The tilt angle increases with increasing baking temperature for making polyimide layer using glass substrate. It was concluded that pretilt angle in the polyimide surface is attributable to the increasing of imide rato.

• 한국전기전자재료학회논문지
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• 제26권9호
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• pp.686-689
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• 2013

The carbon nanowall (CNW) is a carbon-based nanomaterials and it was constructed with vertical structure graphenes and it has the highest surface density among carbon-based nanostructures. In this study, we have checked the growth properties of CNW according to the substrate angle. Microwave plasma enhanced chemical vapor deposition (PECVD) system was used to grow CNW on Si substrate with methane ($CH_4$) and hydrogen ($H_2$) gases. And, we have changed the substrate angle from $0^{\circ}$ to $90^{\circ}$ in steps of $30^{\circ}$. The planar and vertical conditions of the grown CNWs according to the substrate angle were characterized by a field emission scanning electron microscopy (FE-SEM) and energy dispersive spectroscopy (EDS). In case of the growth angle increases, our experimental results showed that the length of the CNW was shortened and the content of carbon component was decreased.

• 한국전기전자재료학회논문지
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• 제16권12호
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• pp.1110-1114
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• 2003

We have investigated the generation of pretilt angle for a nematic liquid crystal (NLC) alignment with rubbing alignment method on polyimide surfaces using thin plastic substrates. It was found that monodomain alignment of NLC is obtained with rubbing alignment method on polyimide surfaces using thin plastic substrates. The NLC pretilt angles generated are about 3$^{\circ}$ by the rubbing alignment method on thin plastic substrates, However, the pretilt angle are at about 1.7$^{\circ}$ lower on the glass substrate than on thin plastic substrate. We obtain that AFM (atomic force microscope) image of rubbed PI surface with polymer film has formed the micro-groove structure at the low curring temperature (120$^{\circ}C$). However, no grooves are obtained on the glass substrate at the same temperature. It is considered that this alignment may be attributed to roughness of micro-groove substrate. The tilt angle increases with increasing baking temperature for making polyimide layer using glass substrate. It was concluded that the pretilt angle in the polyimide surface is attributable to the increasing of imidization rato.

• 한국전기전자재료학회논문지
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• 제17권3호
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• pp.329-332
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• 2004

ZnO thin films were grown with different plume-substrate angles by pulsed laser deposition (PLD) to control the amount of ablated species arriving on a substrate per laser shot. The angles between plume propagation direction and substrate plane (P-S angle) were 0$^{\circ}$, 45$^{\circ}$ and 90$^{\circ}$. The growth time was changed in order to adjust film thickness. From the XRD pattern exhibiting a dominant (002) and a minor (101) XRD peak of ZnO, all films were found to be well oriented along c-axis. From the AFM image, it was found that the grain size of ZnO thin film was increased, as P-S angle decreased. UV intensity investigated by PL (Photoluminescence) increased as P-S angle decreased.

• Transactions on Electrical and Electronic Materials
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• 제6권3호
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• pp.106-109
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• 2005

We have investigated the generation of pretilt angle for a nematic liquid crystal (NLC) alignment with in-situ photoalignment method on polyimide (PI) surfaces using polymer films. Especially, we studied in-situ photoalignment changing heating temperature from $50^{\circ}C\;to\;120^{\circ}C$ on the polymer film. The LC aligning capabilities and pretilt angle on the polymer substrates were better than those on the glass substrate using in-situ photoalignment method. It is considered that this increase in pretilt angle may be attributed to the roughness of the micro-groove substrate induced by the in-situ photoalignment. As temperature of heated subtrate and UV exposure time increase, pretilt angle of the cell used polymer film increased. It is considered that the heating temperature of substrate is attributed to generate pretilt angle. Also, electro-optical performances of the in-situ photoaligned TN cell using the polymer substrate are almost the same as that of the TN cell using the glass substrate.

• 한국기계가공학회지
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• 제21권6호
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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.

• Current Optics and Photonics
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• 제5권1호
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• pp.45-51
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• 2021

The effect of the out-of-plane retardation (Rth) of a substrate film on the viewing-angle dependence of transmittance (TR) in a display device was investigated. When the polarization state of input light deviates from the transmission axis of the polarizer, Rth of the substrate film induces inhomogeneous viewing-angle dependence of TR. The inhomogeneity of TR gets worse for greater values of of Rth. The inhomogeneous TR profile can be eliminated by inserting compensation films, which convert the input polarization state to the linear polarization state parallel to the transmission axis of the polarizer.

• Journal of Electrical Engineering and Technology
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• 제10권4호
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• pp.1738-1745
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• 2015

Radiation characteristics of a probe-fed rectangular microstrip patch antenna printed on a finite grounded high permittivity substrate are investigated systematically for various square grounded dielectric substrate sizes with several thicknesses and dielectric constants by experiment and full wave simulation. The effect of the substrate size on the radiation characteristics of a rectangular patch antenna is mainly determined by the effective dielectric constant of surface waves on a grounded dielectric substrate. As the effective dielectric constant of surface waves increases, the substrate sizes for the maximum broadside gain and the required onset for a large magnitude of squint angle decrease, while the variations of the broadside gain, the front-to-back ratio, and the magnitude of squint angle versus the substrate size increase due to the increase of the power of the surface wave.

• 한국전기전자재료학회논문지
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• 제17권5호
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• pp.526-529
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• 2004

The nematic liquid crysta](NLC) aligning capabilities using a-C:H thin film deposited at the three kinds of rf bias condition were investigated. A high pretilt angle of NLC on low substrate rf bias applied a-C:H thin films was observed and the low pretilt angle of the NLC on high substrate rf bias applied a-C:H thin films was observed. Consequently, the high NLC pretilt angle and the good aligning capabilities of LC alignment by the IB alignment method on the a-C:H thin film deposited at 1 W rf bias condition can be achieved. It is considered that pretilt angle of the NLC may be attributed to substrate rf bias condition and IB energy time. Therefore, LC alignment is affected by topographical structure forming strong IB energy.

• 한국정밀공학회지
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• 제30권4호
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• pp.414-420
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• 2013

We developed inkjet based measurement system for micro-droplet behavior on a substrate. By using the inkjet dispenser, a droplet, which is as small as few pico-liter in volume, can be jetted and the amount can be controlled. After jetting, the droplet image on the substrate is acquired from side view camera. Then, droplet profile is extracted to measure droplet volume, contact angle and evaporation characteristics. Also top view image of the droplet is acquired for better understanding of droplet shape. The previous contact angle measurement method has limitations since it mainly measures the ratio of height and contact diameter of droplet on a substrate. Unlike previous measurement system, our proposed method has advantages because various behavior of droplet on substrate can be effectively analyzed by extracting the droplet profile.