• Transactions on Electrical and Electronic Materials
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• v.7 no.1
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• pp.21-25
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• 2006

In this study, liquid crystal (LC) aligning properties for homeotropic alignment on the $SiO_x$ thin film by electron beam evaporation method with electron beam system in accordance with the evaporation angles were investigated. Also, the control of pretilt angles homeotropic aligned LC on $SiO_x$ thin film as the function of the evaporation angles were studied. The uniform vertical LC alignment on the $SiO_x$ thin film surfaces with electron beam evaporation was achieved with all of the thin film angle conditions. It is considerated that the LC alignment on the $SiO_x$ thin film by electron beam evaporation is attributed to elastic interaction between LC molecules and micro-grooves at the $SiO_x$ thin film surface created by evaporation. The values of the pretilt angles according to the evaporation angle were from about $0.7^{\circ}$ to about $3.4^{\circ}$. The highest pretilt angles of about $3.4^{\circ}$ in aligned NLC on the $SiO_x$ thin film surfaces by electron beam evaporation were measured under the condition of $45^{\circ}$. Also, good LC alignment states on the treated $SiO_x$ thin film layer by electron beam evaporation were observed at annealing temperature of $250^{\circ}C$. Consequently, the high pretilt angle and the good thermal stability of LC alignment on the $SiO_x$ thin film by electron beam evaporation can be achieved.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.48 no.1
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• pp.20-28
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• 2012

The monofilament with 0.304mm of diameter was produced using a polybutylene succinate (PBS) resin, and a gill net was made by it. We investigated the impact of heat setting temperature on the mechanical properties, knot state and height of gill net. Heat treatment was carried out using the high pressure steam machine for 20 minutes at temperature of $55^{\circ}C$, $60^{\circ}C$, $70^{\circ}C$ and $75^{\circ}C$. Before heat treatment, the strength and elongation of PBS monofilament were estimated to be $48.1kg/mm^2$, 23.8% at unknot, $37.6kg/mm^2$, 18.8% at single knot, $26.6kg/mm^2$, 22.9% at double knot in dry condition, respectively. The strength and elongation of PBS monofilament with double knot were decreased as heat setting temperature increased, and the decreasing rate of strength was showed to be higher than that of elongation. It was not found any differences in strength and elongation of PBS monofilament yarn with double knot at the $65^{\circ}C$ and $70^{\circ}C$ of heat setting temperature by 5% significance of T-test, but there was a significant difference at the $70^{\circ}C$ and $75^{\circ}C$ of heat setting temperature. The net's height and length from leg to leg appeared no differences at the $70^{\circ}C$ and $75^{\circ}C$ of heat setting temperature. In results, it was investigated that the PBS monofilament gill net with the maximized physical properties could be manufactured at $70^{\circ}C$ of heat setting temperature using a high pressure steam machine for 20 minutes.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.26-26
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• 2009

Vertically aligned arrays of mm-long multi-walled carbon nanotubes (MWCNTs) on Si substrates have been synthesized by water-assisted thermal chemical vapor deposition (CVD). The growth of CNTs was investigated by changing the experimental parameters such as growth temperature, growth time, gas composition, annealing time, catalyst thickness, and Al underlayer thickness. The 0.5-nm-thick Fe served as catalyst, underneath which Al was coated as a catalyst support as well as a diffusion barrier on the Si substrate. We grew CNTs by adding a little amount of water vapor to enhance the activity and the lifetime of the catalyst. Al was very good at producing the nm-size catalyst particles by preventing "Ostwald ripening". The Al underlayer was varied over the range of 15~40 nm in thickness. The optimum conditions for the synthesis parameters were as follows: pressure of 95 torr, growth temperature of $815^{\circ}C$, growth for 30 min, 60 sccm Ar + 60 sccm $H_2$ + 20 sccm $C_2H_2$. The water vapor also had a great effect on the growth of CNTs. CNTs grew 5.03 mm long for 30 min with the water vapor added while CNTs were 1.73 mm long without water vapor at the same condition. As-grown CNTs were characterized by using scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), and Raman spectroscopy. High-resolution transmission electron microscopy showed that the as-grown CNTs were of ~3 graphitic walls and ~6.6 nm in diameter.

• Current Photovoltaic Research
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• v.4 no.1
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• pp.16-20
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• 2016

$Cu_2ZnSnS_4$ (CZTS) thin films were fabricated by successive electrodeposition of layers of precursor elements followed by sulfurization of an electrodeposited Cu-Zn-Sn precursor. In order to improve quality of the CZTS films, we tried to optimize the deposition condition of absorber layers. In particular, I have conducted optimization experiments by changing the Cu-layer deposition time. The CZTS absorber layers were synthesized by different Cu-layer conditions ranging from 10 to 16 minutes. The sulfurization of Cu/Sn/Zn stacked metallic precursor thin films has been conducted in a graphite box using rapid thermal annealing (RTA). The structural, morphological, compositional, and optical properties of CZTS thin films were investigated using X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM), Raman spectroscopy, and X-ray Flourescenece Spectrometry (XRF). Especially, the CZTS TFSCs exhibits the best power conversion efficiency of 4.62% with $V_{oc}$ of 570 mV, $J_{sc}$ of $18.15mA/cm^2$ and FF of 45%. As the time of deposition of the Cu-layer to increasing, the properties were confirmed to be systematically changed. And we have been discussed in detail below.

• Journal of Sensor Science and Technology
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• v.15 no.3
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• pp.216-221
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• 2006

ZnO thin films prepared by PLD method exhibit an excellent optical property, but may have some problems such as incomplete surface roughness and crystallinity. In this study, undoped ZnO buffer layers were deposited on (0001) sapphire substrates by ultra high vacuum pulse laser deposition (UHV-PLD) and molecular beam epitaxy (MBE) methods, respectively. After post annealing of ZnO buffer layer, undoped ZnO thin films were deposited under different oxygen pressure ($35{\sim}350$ mtorr) conditions. The Arsenic-doped (1, 3 wt%) ZnO thin layers were deposited on the buffer layer of undoped ZnO by UHV-PLD method. The optical property of the ZnO thin films was analyzed by photoluminescence (PL) measurement. The ${\theta}-2{\theta}$ XRD analysis exhibited a strong (002)-peak, which indicates c-axis preferred orientation. Field emission-scanning electron microscope (FE-SEM) revealed that microstructures of the ZnO thin films were varied by oxygen partial pressure, Arsenic doping concentration, and deposition method of the undoped ZnO buffer layer. The denser and smoother films were obtained when employing MBE-buffer layer under lower oxygen partial pressure. It was also found that higher Arsenic concentration gave the enhanced growing of columnar structure of the ZnO thin films.

• Korean Journal of Materials Research
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• v.21 no.2
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• pp.78-82
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• 2011

Mono- and few-layer graphenes were grown on Ni thin films by rapid-thermal pulse chemical vapor deposition technique. In the growth steps, the exposure step for 60 s in $H_2$ (a flow rate of 10 sccm (standard cubic centimeters per minute)) atmosphere after graphene growth was specially established to improve the quality of the graphenes. The graphene films grown by exposure alone without $H_2$ showed an intensity ratio of $I_G/I_{2D}$ = 0.47, compared with a value of 0.38 in the films grown by exposure in H2 ambient. The quality of the graphenes can be improved by exposure for 60 s in $H_2$ ambient after the growth of the graphene films. The physical properties of the graphene films were investigated for the graphene films grown on various Ni film thicknesses and on 260-nm thick Ni films annealed at 500 and $700^{\circ}C$. The graphene films grown on 260-nm thick Ni films at $900^{\circ}C$ showed the lowest $I_G/I_{2D}$ ratio, resulting in the fewest layers. The graphene films grown on Ni films annealed at $700^{\circ}C$ for 2 h showed a decrease of the number of layers. The graphene films were dependent on the thickness and the grain size of the Ni films.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.264-264
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• 2013

Strong metal-support interaction effect is an important issue in determining the catalytic ac-tivity for heterogeneous catalysis. In this study, we investigated the support effect and the role of organic capping layers of two-dimensional Pt nanocatalysts on reducible metal oxide supports under the CO oxidation. Several reducible metal oxide supports including CeO2, Nb2O5, and TiO2 thin films were prepared via sol-gel techniques. The structure, chemical state and optical property were characterized using XRD, XPS, TEM, SEM, and UV-VIS spectrometer. We found that the reducible metal oxide supports have a homogeneous thin thickness and crystalline structure after annealing at high temperature showing the different optical band gap energy. Langmuir-Blodgett technique and arc plasma deposition process were employed to ob-tain Pt nanoparticle arrays with capping and without capping layers, respectively on the oxide support to assess the role of the supports and capping layers on the catalytic activity of Pt catalysts under the CO oxidation. The catalytic performance of CO oxidation over Pt supported on metal oxide thin films under oxidizing reaction conditions (40 Torr CO and 100 Torr O2) was tested. The results show that the catalytic activity significantly depends on the metal oxide support and organic capping layers of Pt nanoparticles, revealing the strong metal-support interaction on these nanocatalysts systems.

• Journal of The Korean Society of Grassland and Forage Science
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• v.38 no.3
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• pp.190-195
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• 2018

Cold, salt and heat are the most critical factors that restrict full genetic potential, growth and development of crops globally. However, clarification of genes expression and regulation is a fundamental approach to understanding the adaptive response of plants under unfavorable environments. In this study, we applied an annealing control primer (ACP) based on the GeneFishing approach to identify differentially expressed genes (DEGs) in Italian ryegrass (cv. Kowinearly) leaves under cold, salt and heat stresses. Two-week-old seedlings were exposed to cold ($4^{\circ}C$), salt (NaCl 200 mM) and heat ($42^{\circ}C$) treatments for six hours. A total 8 differentially expressed genes were isolated from ryegrass leaves. These genes were sequenced then identified and validated using the National Center for Biotechnology Information (NCBI) database. We identified several promising genes encoding light harvesting chlorophyll a/b binding protein, alpha-glactosidase b, chromosome 3B, elongation factor 1-alpha, FLbaf106f03, Lolium multiflorum plastid, complete genome, translation initiation factor SUI1, and glyceraldehyde-3-phosphate dehydrogenase. These genes were potentially involved in photosynthesis, plant development, protein synthesis and abiotic stress tolerance in plants. However, this study provides new insight regarding molecular information about several genes in response to multiple abiotic stresses. Additionally, these genes may be useful for enhancement of abiotic stress tolerance in fodder crops as well a crop improvement under unfavorable environmental conditions.

• Current Photovoltaic Research
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• v.5 no.1
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• pp.15-19
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• 2017

The fossil fuel power consumption generates $CO_2$, which causes the problems such as global warming. Also, the increase in energy consumption has accelerated the depletion of the fossil fuels, and renewable energy is attracting attention. Among the renewable energies, the solar energy gets a lot of attention as the infinite clean energy source. But, the supply level of solar cell is insignificant due to high cost of generation of electric power in comparison with fossil fuels. Thus several researchers are recently doing the research on ultra-low-cost solar cells. Also, $Cu_2O$ is one of the applied materials as an absorption layer in ultra-low-cost solar cells. Cuprous oxide ($Cu_2O$) is highly desirable semiconductor oxide for use in solar energy conversion due to its direct band gap ($E_g={\sim}2.1eV$) and a high absorption coefficient that absorbs visible light of wavelengths up to 650 nm. In addition, $Cu_2O$ has several advantages such as non-toxicity, low cost and can be prepared with simple and cheap methods on large scale. In this work, we fabricated the $Cu_2O$ thin films by reactive sputtering method. The films were deposited with a Cu target with variable parameters such as substrate temperature, rf-power, and annealing condition. Finally, we confirmed the structural properties of thin films by XRD and SEM.

• Tribology and Lubricants
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• v.26 no.6
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• pp.317-321
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• 2010

Thin films of tin sulphide (SnS) have been formed by a novel 2-stage process where-in D.C. magnetron sputtering was used to deposit to thin films of tin (Sn) and the layers then sulphidised using 5% hydrogen sulphide ($H_2S$) gas in Argon. Although it was not found possible to deposit high quality thin films of tin directly onto glass substrates, excellent layers of tin were produced by using molybdenum (Mo) coated glass as the substrate material. The chemical and physical properties of the SnS layers formed were determined using scanning electron microscopy, energy dispersive x-ray analysis, x-ray diffraction studies and using reflectance versus wavelength measurements and these related to the conditions of synthesis. The data shows that it should be possible to produce conventional "substrate structure" devices based on the use of this technology.