• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.7 no.2
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• pp.87-92
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• 2009

Remote detecting system for a radiation contamination using a plastic scintillator and an optical fiber was developed. Using a commercially available silica optical fiber and a plastic scintillator, we tested then for a real possibility as a remote monitoring detector. Also, a plastic scintillator was developed by itself, and evaluated as a radiation sensor. The plastic scintillator was made of epoxy resin, a hardener and an organic scintillation material. The mixture rate of the epoxy resin, hardener and organic scintillator was fixed by using their emission spectrum, transmittance, intensity etc. In this study, in order to decrease the light loss of an incomplete connection between an optical fiber and a scintillator, the optical fiber was inserted into the scintillator during the fabrication process. The senor used a plastic optical fiber and was estimated for its detection efficiency by an optic fiber's geometric factor.

• Journal of the Korean institute of surface engineering
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• v.50 no.5
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• pp.345-351
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• 2017

A double-layered anti-reflective coating with hydrophilic/abrasion-resistant properties was studied using anatase titanium dioxide($TiO_2$) and silicon oxycarbide($SiO_xC_y$) thin film. $TiO_2$ and $SiO_xC_y$ thin films were sequentially deposited on a glass substrate by DC sputtering and PECVD, respectively. The optical properties were measured by UV-Vis-NIR spectrophotometer. The abrasion-resistance and the hydrophilicity were observed by a taber abrasion tester and a contact angle analyzer, respectively. The $TiO_2/SiO_xC_y$ double-layer thin film had an average transmittance of 91.3%, which was improved by 10% in the visible light region (400 to 800 nm) than that of the $TiO_2$ single-layer thin film. The contact angle of $TiO_2/SiO_xC_y$ film was $6.9^{\circ}$ right after UV exposure. After 9 days from the exposure, the contact angle was $10.2^{\circ}$, which was $33^{\circ}$ lower than that of the $TiO_2$ single-layer film. By the abrasion test, $SiO_xC_y$ film showed a superior abrasion-resistance to the $TiO_2$ film. Consequently, the $TiO_2/SiO_xC_y$ double-layer film has achieved superior anti-reflection, hydrophilicity, and abrasion resistance over the $TiO_2$ or $SiO_xC_y$ single-layer film.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.54-54
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• 2010

Zinc oxide is metal oxide semiconductor with the 3.37 eV bandgap energy. Zinc oxide is very attractive materials for many application fields. Zinc Oxide has many advantages such as high conductivity and good transmittance in visible region. Also it is cheaper than other semiconductor materials such as indium tin oxide (ITO). Therefore, ZnO is alternative material for ITO. ZnO is attracting attention for its application to transparent conductive oxide (TCO) films, surface acoustic wave (SAW), films bulk acoustic resonator (FBAR), piezoelectric materials, gas-sensing, solar cells and photocatalyst. In this study, we synthesized ZnO nanoparticles and defined their physical and chemical properties. Also we studied about the application of ZnO nanoparticles as a photocatalyst and try to find a enhancement photocatalytic activity of ZnO nanorticles.. We synthesized ZnO nanoparticles using spray-pyrolysis method and defined the physical and optical properties of ZnO nanoparticles in experiment I. When the ZnO are exposed to UV light, reduction and oxidation(REDOX) reaction will occur on the ZnO surface and generate ${O_2}^-$ and OH radicals. These powerful oxidizing agents are proven to be effective in decomposition of the harmful organic materials and convert them into $CO_2$ and $H_2O$. Therefore, we investigated that the photocatalytic activity was increased through the surface modification of synthesized ZnO nanoparticles. In experiment II, we studied on the stability of ZnO nanoparticles in water. It is well known that ZnO is unstable in water in comparison with $TiO_2$. $Zn(OH)_2$ was formed at the ZnO surface and ZnO become inactive as a photocatalyst when ZnO is present in the solution. Therefore, we prepared synthesized ZnO nanoparticles that were immersed in the water and dried in the oven. After that, we measured photocatalytic activities of prepared samples and find the cause of their photocatalytic activity changes.

• Korean Journal of Materials Research
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• v.22 no.10
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• pp.562-568
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• 2012

Metal nanowires can be coated on various substrates to create transparent conducting films that can potentially replace the dominant transparent conductor, indium tin oxide, in displays, solar cells, organic light-emitting diodes, and electrochromic windows. One issue with these metal nanowire based transparent conductive films is that the resistance between the nanowires is still high because of their low aspect ratio. Here, we demonstrate high-performance transparent conductive films with silver nanofiber networks synthesized by a low-cost and scalable electrospinning process followed by two-step sequential thermal treatments. First, the PVP/$AgNO_3$ precursor nanofibers, which have an average diameter of 208 nm and are several thousands of micrometers in length, were synthesized by the electrospinning process. The thermal behavior and the phase and morphology evolution in the thermal treatment processes were systematically investigated to determine the thermal treatment atmosphere and temperature. PVP/$AgNO_3$ nanofibers were transformed stepwise into PVP/Ag and Ag nanofibers by two-step sequential thermal treatments (i.e., $150^{\circ}C$ in $H_2$ for 0.5 h and $300^{\circ}C$ in Ar for 3 h); however, the fibrous shape was perfectly maintained. The silver nanofibers have ultrahigh aspect ratios of up to 10000 and a small average diameter of 142 nm; they also have fused crossing points with ultra-low junction resistances, which result in high transmittance at low sheet resistance.

• Korean Journal of Food Science and Technology
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• v.18 no.3
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• pp.192-196
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• 1986

Cold gelatinization of two naked burley (Songhak and Youngsan) starches in NaOH (0.14-0.21N) and KSC N (1.5-4.5M) was compared. Light transmittance of starch suspension in aqueous NaOH solution was higher in Youngsan starch than in Songhak starch. Viscosity of Youngsan starch was also higher at various starch concentrations (5-12.5%), however the critical concentration of NaOH for the gelatinization of Youngsan starch was lower by 0.1meq NaOH/g starch compared to Songhak starch. Two starches held a linear relationship between viscosity development rate and alkali concentration at a fixed starch concentration. The viscosity development rate of the starch was linearly decreased as starch concentration increased at a fixed alkali concentration. Gel volume of the starches was attained maximum at 2.5M KSCN, however Youngsan starch showed a higher volume and a less stability in KSCN than Songhak starch.

• Journal of the Semiconductor & Display Technology
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• v.9 no.3
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• pp.53-58
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• 2010

In this study, we have investigated the effect of the ambient gases on the characteristics of IZO thin films for the OLED (organic light emitting diodes) devices. For this purpose, IZO thin films were deposited by RF magnetron sputtering under various ambient gases (Ar, $Ar+O_2$ and $Ar+H_2$) at $150^{\circ}C$. In order to investigate the influences of the oxygen and hydrogen, the flow rate of oxygen and hydrogen in argon mixing gas has been changed from 0.1sccm to 0.5sccm, respectively. All the samples show amorphous structure regardless of ambient gases. The electrical resistivity of IZO film increased with increasing flow rate of $O_2$ under $Ar+O_2$ while under $Ar+H_2$ atmosphere the electrical resistivity showed minimum value near 0.5sccm of $H_2$. All the films showed the average transmittance over 85% in the visible range. The OLED device was fabricated with different IZO substrates made by configuration of IZO/${\alpha}$-NPD/DPVB/$Alq_3$/LiF/Al to elucidate the performance of IZO substrate. OLED devices with the amorphous-IZO (a-IZO) anode film show better current densityvoltage-luminance characteristics than that of OLED devices with the commercial crystalline-ITO (c-ITO) anode film. It can be explained that very flat surface roughness and high work function of a-IZO anode film lead to more efficient hole injection by reduction of interface barrier height between anode and organic layers. This suggests that a-IZO film is a promising anode materials substituting conventional c-ITO anode in OLED devices.

• Journal of the Korean institute of surface engineering
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• v.54 no.6
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• pp.302-306
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• 2021

SnO₂ 30/Ag 15/SnO₂ 30 nm(SAS) tri-layer films were deposited on the glass substrates with RF and DC magnetron sputtering and then electron beam is irradiated on the surface to investigate the effect of electron bombardment on the opto-electrical performance of the films. electron beam irradiated tri-layer films at 1000 eV show a higher figure of merit of 2.72×10^-3 Ω^-1 than the as deposited films due to a high visible light transmittance of 72.1% and a low sheet resistance of 14.0 Ω/☐, respectively. From the observed results, it is concluded that the post-deposition electron irradiated SnO₂ 30/Ag 15/SnO₂ 30 nm tri-layer films can be used as a substitute for conventional transparent conducting oxide films in various opto-electrical applications.

• Current Photovoltaic Research
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• v.6 no.4
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• pp.102-108
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• 2018

A glass-texturing technique was developed for photovoltaic (PV) module cover glass; periodic honeycomb textures were formed by using a conventional lithography technique and diluted hydrogen fluoride etching solutions. The etching conditions were optimized for three different types of textured structures. In contrast to a flat glass substrate, the textured glasses were structured with etched average surface angles of $31-57^{\circ}$, and large aspect ratios of 0.17-0.47; by using a finite difference time-domain simulation, we show that these textured surfaces increase the amount of scattered light and reduce reflectance on the glass surface. In addition, the optical transmittance of the textured glass was markedly improved by up to 95% for wavelengths ranging from 400 to 1100 nm. Furthermore, applying the textured structures to the cover glass of the PV module with heterojunction with intrinsic thin-layer crystalline silicon solar cells resulted in improvements in the short-circuit current density and module efficiency from 39 to $40.2mA/cm^2$ and from 21.65% to 22.41%, respectively. Considering these results, the proposed method has the potential to further strengthen the industrial and technical competitiveness of crystalline silicon solar cells.

• Membrane Journal
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• v.31 no.5
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• pp.333-342
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• 2021

A flexible electrochromic device (ECD) is a promising technology that is expected to be applied in various fields such as smart windows. Polymer electrolyte is an important component that determines the bleaching-coloration performance and physical stability of flexible ECDs. In this study, a pore-filled polymer electrolyte membrane (PFPEM) with excellent dimensional stability was developed to effectively fabricate flexible ECDs and improve durability. Polyvinyl acetate, which has excellent adhesion, and polyethylene glycol, which can improve ionic conductivity, were filled in the pores of a porous substrate made of polyethylene, which is inexpensive and has excellent physical and chemical stability. The optimal lithium salt (LiTFSI) content of the prepared PFPEM was determined at about 27 wt%, and it was confirmed to possess excellent dimensional stability, adhesive strength, and ion conductivity close to that of conventional polymer electrolytes. Although the visible light transmittance was lowered by the use of the porous substrate, it was expected to act as an advantage in the colored state.

• New & Renewable Energy
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• v.16 no.4
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• pp.76-82
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• 2020

Soiling on the surface of a PV module reduces the amount of light reaching the solar cells, decreasing power performance. The performance of the PV module is generally restored after contaminants on the module surface are washed away by rain, but it accumulates at the bottom of the module owing to the thickness of the module frame, causing an output mismatch on the PV module. Since PV modules are usually installed horizontally or vertically outdoors, soiling can occur at the bottom of the PV module, depending on the installation direction due to external environmental factors. This paper is analyzed the output characteristics of a PV module considering its installation direction and the soiling area. The soiling was simulated to use transparent films with 5% transmittance, and the transmission film was attached to the bottom part of the PV module horizontally and vertically. When the soiling area was 33% of the string at the bottom of the PV module, the power output decreased similarly regardless of installation direction. However, when the soiling area was 66% of the string at the bottom of the PV module, it was confirmed that the output performance decreased sharply when installed vertically rather than horizontally.