• Journal of the Korean institute of surface engineering
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• v.52 no.2
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• pp.84-89
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• 2019

We fabricated durable anti-reflective(AR) layer with silica globular coating on polymer by two steps. Firstly, nano-protrusions of polymer were formed by plasma etching known as R.I.E(reactive ion etching) process. Secondly, silica globular coating was deposited on polymer nano-protrusions for mechanically protective and optically enhancing AR layers by RF magnetron sputter. And then durable antireflective polymers were synthesized adjusting plasma power and time, working pressures of RIE and RF sputtering processes. Consequently, we acquired the average transmission (94.10%) in the visible spectral range 400-800 nm and the durability of AR layer was verified to sustain its transmission until 5,000 numbers by rubber test at a load of 500 gf.

• Proceedings of the Korean Magnestics Society Conference
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• 2006.11a
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• pp.56-56
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• 2006

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1999.12a
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• pp.93-99
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• 1999

It is definite trend that the functional devices are to be integrated by miniaturizing of individual components. Bulk crystals turn into wafer form, while thin film of the functional materials is being fabricated for single and multi-layer devices. In addition, single crystals with multi-function performance would be desirable for further miniaturization. crystal growers have the responsibility for synthesis single crystals work to meet ever increasing requirement of future devices.

• Proceedings of the Korean Vacuum Society Conference
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• 2004.08a
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• pp.116-116
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• 2004

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.2
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• pp.153-157
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• 2006

In this work, the effects of plasma treatment on surface properties of semiconductive silicone rubber were investigated in terms of X-ray photoelectron spectroscopy (XPS) and contact angles, The adhesion characteristics of semiconductive-insulating interface layer of silicone rubber were studied by measuring the T-peel strengths, The results of the chemical analysis showed that C-H bonds were broken due to plasma discharge and Silica-like bonds(SiOx, x=3${\~}$4) increased, It is thought that semiconductive silicone rubber surfaces treated with plasma discharge led to an increase in oxygen-containing functional groups, resulting in improving the degree of adhesion of the semiconductive-insulating interface layer of silicone rubber. However, the oxygen plama for 20 minute produces a damaged oxidized semiconductive silicone rubber layer, which acts as a weak layer producing a decrease in T-peel strength, These results are probably due to the modifications of surface functional groups or polar component of surface free energy of the semiconductive silicone rubber.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.7
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• pp.417-422
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• 2017

A high-performing photoelectric device was realized for the $MoS_2$-embedded Si device. $MoS_2$-coating was performed by an available large-scale sputtering method. The $MoS_2$-layer coating on the p-Si spontaneously provides the rectifying current flow with a significant rectifying ratio of 617. Moreover, the highly optical transmittance of the $MoS_2$-layer provides over 80% transmittance for broad wavelengths. The $MoS_2$-embedded Si photodetector shows the sensitive photo-response for middle and long-wavelength photons due to the functional $MoS_2$-layer, which resolves the conventional limit of Si for long wavelength detection. The functional design of $MoS_2$-layer would provide a promising route for enhanced photoelectric devices, including photovoltaic cells and photodetectors.

• Steel and Composite Structures
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• v.29 no.5
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• pp.569-578
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• 2018

This paper aims to investigate the transient vibration behavior of functionally graded carbon nanotube (FG-CNT) reinforced nanocomposite plate resting on Pasternak foundation under pulse excitation. The plate is considered to be composed of matrix material and multi-walled carbon nanotubes (MWCNTs) with distribution as per the functional grading concept. The functionally graded distribution patterns in nanocomposite plate are explained more appropriately with the layer-wise variation of carbon nanotubes weight fraction in the thickness coordinate. The layers are stacked up in such a way that it yields uniform and three other types of distribution patterns. The effective material properties of each layer in nanocomposite plate are obtained by modified Halpin-Tsai model and rule of mixtures. The governing equations of an illustrative case of simply-supported nanocomposite plate resting on the Pasternak foundation are derived from third order shear deformation theory and Navier's solution technique. A converge transient response of nanocompiste plate under uniformly distributed load with triangular pulse is obtained by varying number of layer in thickness direction. The validity and accuracy of the present model is also checked by comparing the results with those available in literature for isotropic case. Then, numerical examples are presented to highlight the effects of distribution patterns, foundation stiffness, carbon nanotube parameters and plate aspect ratio on the central deflection response. The results are extended with the consideration of proportional damping in the system and found that nanocomposite plate with distribution III have minimum settling time as compared to the other distributions.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.1
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• pp.68-74
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• 2018

All transparent UV photodetector based on ZnO was fabricated with structure of NiO/ZnO/$SnO_2$/ITO by using RF and DC magnetron sputtering system. ZnO was deposited with 4 inch ZnO target (purity 99.99%) for a quality film. In order to build p-n junction up, p-type NiO was formed on n-type ZnO by using reactive sputtering method. The indium tin oxide (ITO) which is transparent conducting oxide (TCO) was applied as a transparent electrode for transporting electrons. To improve the UV photodetector performance, a functional $SnO_2$ layer was selected as an electron transporting and hole blocking layer, which actively controls the carrier movement, between ZnO and ITO. The photodetector (NiO/ZnO/$SnO_2$/ITO) shows transmittance over 50% as similar as the transmittance of a general device (NiO/ZnO/ITO) due to the high transmittance of $SnO_2$ for broad wavelengths. The functional $SnO_2$ layer for band alignment effectively enhances the photo-current to be $15{\mu}A{\cdot}cm^{-2}$ (from $7{\mu}A{\cdot}cm^{-2}$ of without $SnO_2$) with the quick photo-responses of rise time (0.83 ms) and fall time (15.14 ms). We demonstrated the all transparent UV photodetector based on ZnO and suggest the route for effective designs to enhance performance for transparent photoelectric applications.

• Journal of the Korean Applied Science and Technology
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• v.26 no.4
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• pp.467-472
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• 2009

Ultraviolet curable coating solution was prepared with poly(ethylene glycol) acrylate oligomer and various mono and multi-functional acrylate monomers. The optical properties of UV cured coating layer on PET film with acrylate coating solution containing metal oxides, such as fumed silica and alumina, were also investigated to reduce light reflection on films. Poly(ethylene glycol) diacrylate which has 575 of average molecular weight was used as oligomer acrylate, and pentaerythritol triacrylate and dipentaerythritolpenta-/hexa acrylate were used as multi-functional acrylate monomers. Also, butyl acrylate was used to improve the adhesion as well as to reduce glass transition temperature to give a better flexability. 1-hydroxy cyclohexyl phenyl ketone was used as photoinitiator. We found out the metal oxides in acrylate coating solution showed a homogeneous dispersion from energy dispersive spectroscopy data. Transmittance and light reflection of coated PET film was measured with UV/vis spectrometer and gloss meter, respectively. When 1.00 g of both metal oxides was added into coating solution, the transmittance and the glossiness were reduced from 90% to 30% and from 190 GU to 35 GU, respectively. However, adding up to 1.00 g of the metal oxide into coating solution did not affect on the hardness of coating layer and adhesion between coated layer and PET film. Conclusively, we can control transmittance and light reflection of coated film by adjusting the amounts of metal oxide in coating solution.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05a
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• pp.27-31
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• 2001

We fabricated organic electroluminescent(EL) devices with mixed emitting layer of poly(N-vinylcarbazole)(PVK), 2,5-bis(5'-tert-butyl-2-benzoxazoly)thiophene(BBOT), N,N'-diphenyl-N,N'-(3-methyphenyl)-1,1'-biphenyl-4, 4'-diarnine(TPD) and poly(3-hexylthiophene)(P3HT). To improve the external quantum efficiency of EL devices, we added the functional layer to the devices such as LiF insulating layer, carrier confinement layer(BBOT) and hole injection layer(CuPc). In the ITO/emitting layer/Al device, the maximum quantum efficiency at 15V was $1.88{\times}10^{-5}%$. And then, it is increased by a factor of 27 to $5.2{\times}10^{-3}%$ in ITO/CuPc/emitting layer/BBOT/LiF/Al device at 15V.