• Journal of Sensor Science and Technology
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• v.29 no.2
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• pp.118-122
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• 2020

This paper proposes a specific sensor-design strategy and the possibility of improving the sensing performance, which can be obtained by replacing part of the existing plasmonic sensor based on the Kretschmann configuration method with an effective refractive-index layer. By replacing the metal layer with an effective refractive-index layer composed of gold and the material to be sensed, an improvement in the detection performance, accompanied by an increase in the sensed incident angle, is observed, and the gold-composition ratio that demonstrates the best result is presented. Subsequently, an increase in the sensed incident angle generated in the previous step can be suppressed by randomly etching a portion of the prism adjacent to the metal layer in a sub-wavelength scale. Finally, this study analyzes the optimization of the metal-layer thickness in a given sensor structure. An effective refractive thin-film surface plasmon resonance sensor design that can achieve optimal sensing performance is then proposed.

• Proceedings of the KIEE Conference
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• 2008.10a
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• pp.171-172
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• 2008

$(Ba_{0.57}Sr_{0.33}Ca_{0.10})TiO_3$ (BSCT) thick films doped with 0.1 mol% $MnCO_3$ and $Yb_2O_3$ ($0.1{\sim}0.7$ mol%) were fabricated by the screen printing method on the alumina substrate. And the structural and electrical properties as a function of $Yb_2O_3$ amount were investigated. The lattice constants of the BSCT thick film doped with 0.1 mol% is 0.3955 nm. The specimen doped with 0.7 mol% $Yb_2O_3$ showed dense and uniform grains with diameters of about 6.3 mm. The thickness of all BSCT thick films was approximately 60 mm. The Curie temperature of the BSCT specimen doped with 0.1 mol% $Yb_2O_3$ was $18^{\circ}C$, and the dielectric constantand dielectric loss at this temperature was 4637 and 4.2%, respectively. The BSCT specimen doped with 0.1 mol% $Yb_2O_3$ showed the maximum value of $349{\times}10^{-9}C/cm^2K$ at Curie temperature. The figure of merit $F_D$ for specific detectivity of the specimens doped with 0.1 mol% $Yb_2O_3$ showed the highest value of $10.9{\times}10^{-9}Ccm/J$.

• The Journal of Korea Robotics Society
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• v.8 no.3
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• pp.156-163
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• 2013

This paper describes a flexible visuo-haptic display module. We have developed a flexible electro-active polymer (EAP) actuator and a thin flexible visual display with $3{\times}3$ array configuration via polymer technology. The flexible actuator consists of nine EAP cells vertically moving in response to change in their thickness. The flexible display uses polymer based optical waveguide allowing light to scatter only at specific area. The display film is transparent and identically designed to the array pattern to fit for the arrangement of actuator cells. A pressure sensor is installed under the integrated module. The performance of the actuator is proved to be sufficient for satisfying perceivable range of human touch sense. The integrated system can provide interactive haptic feedback such as key pressing, contact vibration sensations, and etc. in accordance with user input.

• Journal of Information Display
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• v.10 no.3
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• pp.131-136
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• 2009

This is a report on the fabrication of a flexible OTFT backplane for electrophoretic display (EPD) using a printing technology. A practical printing technology for a polycarbonate substrate was developed by combining the conventional screen and inkjet printing technologies with the wet etching and oxygen plasma processes. For the gate electrode, the screen printing technology with Ag ink was developed to define the minimum line width of ${\sim}5{\mu}m$ and the thickness of ${\sim}70nm$ with the resistivity of ${\sim}10^{-6}{\Omega}{\cdot}cm$, which are suitable for displays with SVGA resolution. For the source and drain (S/D) electrodes, PEDOT:PSS, whose conductivity was drastically enhanced to 450 S/cm by adding 10 wt% glycerol, was adopted. In addition, the modified PEDOT:PSS could be neatly confined in the specific S/D electrode area that had been pretreated with oxygen. The OTFTs that made use of the developed printing technology produced a mobility of ${\sim}0.13cm^2/Vs.ec$ and an on/off current ratio of ${\sim}10^6$, which are comparable to those using thermally evaporated Au for the S/D electrode.

• Journal of the Korean institute of surface engineering
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• v.41 no.1
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• pp.38-42
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• 2008

316L stainless steel welding tube was electrolytically polished and the inner surface characteristics of the tube were tested. Electro-polishing variables such as current, voltage, concentration of electrolyte and electropolishing time were changed to seek for optimum condition. These makes a optimum conditions for the electro-polishing as 4000 A, 9 V, 1.7 specific gravity of electrolyte, and 30 minute of electro-polishing time. It makes the surface roughness as Ra < $0.25{\mu}m$. XPS test resulted as the ratio of CrO/FeO equals or more to 3/1. AES test resulted as the thickness of CrO film of $38{\AA}$. DTA test resulted as the tube did not react with $N_2,\;H_2\;and\;O_2$ gas below 1073K. As summarize above results, the electro- polished 316L stainless steel welding tube satisfied the conditions to apply as a pipeline for semi- conductor production facility and clean room.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2005.09a
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• pp.201-212
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• 2005

[ $Epoxy/BaTiO_3$ ] composite embedded capacitor films (ECFs) were newly designed fur high dielectric constant and low tolerance (less than ${\pm}15\%$) embedded capacitor fabrication for organic substrates. In terms of material formulation, ECFs are composed of specially formulated epoxy resin and latent curing agent, and in terms of coating process, a comma roll coating method is used for uniform film thickness in large area. Dielectric constant of $BaTiO_3\;&\;SrTiO_3$ composite ECF is measured with MIM capacitor at 100 kHz using LCR meter. Dielectric constant of $BaTiO_3$ ECF is bigger than that of $SrTiO_3$ ECF, and it is due to difference of permittivity of $BaTiO_3\;and\;SrTiO_3$ particles. Dielectric constant of $BaTiO_3\;&\;SrTiO_3$ ECF in high frequency range $(0.5\~10GHz)$ is measured using cavity resonance method. In order to estimate dielectric constant, the reflection coefficient is measured with a network analyzer. Dielectric constant is calculated by observing the frequencies of the resonant cavity modes. About both powders, calculated dielectric constants in this frequency range are about 3/4 of the dielectric constants at 1 MHz. This difference is due to the decrease of the dielectric constant of epoxy matrix. For $BaTiO_3$ ECF, there is the dielectric relaxation at $5\~9GHz$. It is due to changing of polarization mode of $BaTiO_3$ powder. In the case of $SrTiO_3$ ECF, there is no relaxation up to 10GHz. Alternative material for embedded capacitor fabrication is $epoxy/BaTiO_3$ composite embedded capacitor paste (ECP). It uses similar materials formulation like ECF and a screen printing method for film coating. The screen printing method has the advantage of forming capacitor partially in desired part. But the screen printing makes surface irregularity during mask peel-off, Surface flatness is significantly improved by adding some additives and by applying pressure during curing. As a result, dielectric layer with improved thickness uniformity is successfully demonstrated. Using $epoxy/BaTiO_3$ composite ECP, dielectric constant of 63 and specific capacitance of 5.1nF/cm2 were achieved.

• Composites Research
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• v.20 no.3
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• pp.8-16
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• 2007

Bending collapse of light-weight square tubes used for vehicle structure components is a dominant failure mode in oblique collision and rollover of vehicles. In this paper bending performances of aluminum-GFRP hybrid tube beams were evaluated in relation with bending deformation behavior and energy absorption characteristics. Aluminum/GFRP hybrid tube beams fabricated by inserting adhesive film between prepreg and metal layer were used in the bending test. Failure mechanisms of hybrid tubes under a bending load were experimentally investigated to analyze the bending performance as a function of ply orientation and composite layer thickness. Ultimate bending moments and energy absorption capacity of hybrid tube beams were obtained from the measured load-displacement corves. It was found that aluminum/GFRP hybrid tubes could be converted to rather stable collapse mode showing excellent energy absorption capacity in comparison to the pure aluminum tube beams. In particular, the hybrid tube beam with $[0^{\circ}/90^{\circ}]s$ composite layer showed a large improvement by about 78% in energy absorption capacity and by 29% in specific energy absorption.

• Journal of the Microelectronics and Packaging Society
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• v.27 no.4
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• pp.25-37
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• 2020

In this study, hybridization of graphene oxide and metal was carried out by the functional groups containing oxygen and thermal treatment for reduction in order to enhance the electrical conductivity and magnetic properties of graphene materials. Graphene-metal hybrid materials were synthesized using the oxygen-containing functional groups (-OH, -COOH and so on) on the surface of graphene oxide by replacing them with metal ions via ion exchange method as well as thermal reduction. The metals used in this study were Fe, Ag, Ni, Zn, and Fe/Ag, and it was confirmed that metal particles of uniform size were well dispersed on the graphene surface through SEM, TEM, and EDS. All of the metal particles on the graphene surface had an oxide-crystalline structure. To check the electrical properties, sheet resistance of the rGO-metal hybrid sample was measured on the PET film made by the dip-coating, and the specific resistance was calculated by measuring the thickness of the specimen through SEM. As a result, the specific resistance was in the range of 2.14×10-5 and 3.5×10-3 ohm/cm.

• Clean Technology
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• v.19 no.4
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• pp.410-415
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• 2013

The supercapacitors were fabricated using silver (Ag) nano paste and activated carbon paste on the polyimide (PI) film and 5% potassium polyacrylate (PAAK) was used for gel electrolyte. In this paper, the current collector film and the electrode film were fabricated using screen printing. The thickness of printed silver paste was $7.3{\mu}m$ and the sheet resistance has the range of $5-7m{\Omega}/square$. An activated carbon with a surface area of $1,968m^2/g$, an electronic conducting agent (SUPER P, TIMCAL) and poly (4-vinylphenol) were mixed in 2-(2-buthoxyethoxy) ethyl acetate (BCA) with a ratio of 7:1:3 to fabricate the electrode paste. To analyze electrochemical characteristics, cyclic voltammetry was performed to evaluate the stability of the devices under the voltage range of -0.5-0.5 V. The calculated specific capacitances were 44.04 and 8.62 F/g for 10 and 500 mV/s scan rates, respectively.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.14 no.5
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• pp.438-443
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• 2021

This paper uses a multiplex deposition sputter system and aims to improve transmittance and reduce production costs by depositing a CdS thin film on an ITO glass substrate. When manufacturing CdS thin films, we wanted to find excellent conditions when manufacturing solar cells by changing heat treatment time. It was observed that thickness and sheet resistance were not significantly different depending on heat treatment time changes. The specific resistance was measured from a minimum of 6.68 to a maximum of 6.98. When the heat treatment time was more than 20 minutes, the transmittance was measured to be more than 75%. When the heat treatment time was 10 minutes, the bandgap was 3.665 eV and more than 20 minutes was 3.713 eV, which was measured as the same result. The XRD analysis showed that the structure of CdS was hexagonal and only CdS thin films were deposited without any other impurities. The result of calculating the FWHM was a maximum of 0.142 when the heat treatment time was 20 minutes, and a minimum of 0.133 when the heat treatment time was 40 minutes, so there was no significant difference in the FWHM when the heat treatment time was changed. The particle size was measured at 11.65 Å when the heat treatment time was 40 minutes, and at 10.93 Å when the heat treatment time was 20 minutes.