• Rapid Communication in Photoscience
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• 제4권1호
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• pp.19-21
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• 2015

Zeolite is an ideal host material for encapsulating nano-size metal catalyst species because of its defined microporous structure, prominent adsorption/condensation properties, high surface area, chemical/thermal stability, and transparency to light. In this study, $TiO_2$ photocatalyst was incorporated in highly hydrophobic Y zeolite and its photocatalytic activity was examined in the photocatalytic oxidation of olefins under UV-light irradiation using molecular oxygen as an oxygen source. $TiO_2$ nanoparticles incorporated in hydrophobic Y zeolite exhibited a markedly enhanced photocatalytic activity compared with bare $TiO_2$ owing to its excellent affinity toward organic moieties, which facilitates the mass transfer of organic substrates and allows them to efficiently access to the neighboring active $TiO_2$ surface.

• Proceedings of the KIEE Conference
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• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 C
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• pp.422-424
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• 2000

ZnO thin films for light emission device have been deposited on sapphire and silicon substrates by pulsed laser deposition technique(PLD). A Nd:YAG laser was used with the wavelength of 355 nm. In order to investigate the emission properties of ZnO thin films, PL measurements with an Ar ion laser as a light source using an excitation wavelength of 351 nm and a power of 100 mW are used. All spectra were taken at room temperature by using a grating spectrometer and a photomultiplier detector. ZnO exhibited PL bands centered around 390, 510 and 640 nm, labeled near ultra-violet (UV), green and orange bands. Structural properties of ZnO thin films are analized with X-ray diffraction (XRD).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• 제20권5호
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• pp.456-461
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• 2007

In this study, a surface treatment method using accelerated Ar ions was experimented for exposing the carbon nanotubes (CNT) from the screen-printed CNT paste. After making a cathode electrode on the glass substrate, photo sensitive CNT paste was screen-printed, and then back-side was exposed by UV light. Then, the exposed CNT paste was selectively remained by development. After post-baking, the remained CNT paste was bombarded by accelerated Ar ions for removing some binders and exposing only CNTs. As results, the field emission characteristics were strongly depended on the accelerating energy, bombardment time, and the power of RF plasma ion source. When Ar ions accelerated with 100 eV energy from the 100 W RF plasma source are bombarded on the CNT paste surface for 10 min, the emission level and the uniformity were best.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 추계학술대회 논문집
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• pp.382-382
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• 2009

염료감응형 태양전지의 구성체 중 전극으로 연구 되어 지고 있는 $TiO_2$는 기존에 대량 생산이 가능한 spin coating법, screen printing법, spray법의 연구가 이루어져 왔으나 고 효율 태양전지에 쓰이는 전극 시스템에 비해 고 분산성을 지닌 $TiO_2$페이스트를 제조 하는데 어려움이 있다. 그리고 플렉시블 디스플레이 소자의 응용을 위해서는 소자 공정 온도인 $250^{\circ}C$ 이하의 공정 온도가 요구 되어 지므로 고온공정인 CVD법은 이에 적합하지 않다. 이에 본 연구는 진공 증착 방법인 광원자층증착법을 이용하여 $150^{\circ}C$이하의 저온공정온도에서도 적용이 가능한 $TiO_2$ 박막을 185nm의 UV light를 조사하여 glass 기판위에 제조 하고 그에 따른 박막의 물성 분석을 하였다. Mo source로는 titanium tetraisopropoxide(TTIP)와 reactant gas 로는 $H_2O$를 사용하였으며 불활성 기체인 Ar 가스는 purge 가스로 각각 사용하였다. $100^{\circ}C{\sim}250^{\circ}C$ 공정온도를 변수로 $TiO_2$ 박막을 제조 하였으며 제조된 $TiO_2$ 박막의 물성 분석을 위해 FESEM, TEM을 이용하여 표면 및 두께를 분석하였다. 또한 $100^{\circ}C$ 400 cycles에서 약 12nm 막 두께를 관찰 할 수 있었으며 그 결과 박막의 성장률이 $0.3{\AA}$/cycle 임을 확인 할 수 있었다. 그리고 UV-VIS을 이용하여 박막의 좌외선에 대한 흡수도 및 투과도 분석을 하였다. 또한 XPS 성분 분석을 통하여 $100^{\circ}C$의 저온 공정에서 형성된 박막이 $TiO_2$임을 확인 하였다. 이러한 결과에서 185nm의 UV light에 의한 광원자층 증착법으로 $100^{\circ}C$의 저온에서도 $TiO_2$ 박막이 증착 되는 것을 확인 할 수 있었다.

• Journal of the Microelectronics and Packaging Society
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• 제27권4호
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• pp.113-117
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• 2020

In this paper, We investigated the effect of heat treatment process using photo-thermal effect in order to improve mechanical properties of nanostructure on polymer films made by nanoimprint process with hybrid resin. Nanostructures which have a low refractive characteristic were fabricated by UV nanoimprint and after that heat treatment was performed using IPL (intense pulsed light) under process condition of 550 V voltage, pulse width 5 ms, frequency 0.5 Hz. The transmittance and mechanical property of fabricated nanostructure films were evaluated to observe changes in the pattern transfer rate and mechanical properties of nanostructures. The transmittance of the nanostructure was measured at 97.6% at 550 nm wavelength. Nanoindentation was performed to identify improved anti-scatch properties. Result was compared by the heat source. In case of post treatment with IPL, hardness was 0.51 GPa and in the case of hotplate was 0.27 GPa, resulting the increase of hardness of 1.8 times. Elastic modulus of IPL treated sample was 5.9GPa and Hotplate treated one was 4GPa, showing the 1.4 time increase.

• Environmental Engineering Research
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• 제13권3호
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• pp.136-140
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• 2008

$TiO_2$ photocatalyst has been known to exhibit a notable disinfecting activity against a broad spectrum of microorganisms. A lot of commercial $TiO_2$ photocatalyst products have been developed for antimicrobial purposes. However, a standard method has not yet been proposed for use in testing antimicrobial activity. In this study, we developed a $TiO_2$ photocatalytic adhesion test method with film as the standard testing method for the evaluation of antimicrobial activity. This method was devised by modifying the previous antimicrobial products test method, which has been widely used, and considering the characteristics of $TiO_2$ photocatalytic reaction. The apparatus for testing the antimicrobial activity was composed of a Black Light Blue (BLB) lamp as UV-A light source, a Petri dish as the cover material, and a polypropylene film as the adhesion film. The standard $TiO_2$ photocatalyst sample, Degussa P25 $TiO_2$ - coated glass, could only be used once. The optimal initial concentration of the microorganism, proper light intensity, and light irradiation time were determined to be $10^6$ CFU/mL, 1.0 mW/$cm^2$, and 3 hr, respectively, for testing and evaluating antimicrobial activity on the $TiO_2$ surface.

• Journal of Korean Society of Environmental Engineers
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• 제39권1호
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• pp.9-18
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• 2017

Arsenic (As) has been considered as the most toxic one among various hazardous materials and As contamination can be caused naturally and anthropogenically. Major forms of arsenic in groundwater are arsenite [(As(III)] and/or arsenate [(As(V)], depending on redox condition: arsenite and arsenate are predominant in reduced and oxidized environments, respectively. Because arsenite is much more toxic and mobile than arsenate, there have been a number of studies on the reduction of its toxicity through oxidation of As(III) to As(V). This study was initiated to develop photocatalytic oxidation process for treatment of groundwater contaminated with arsenite. The performance of two types of light sources (UV lamp and UV LED) was compared and the feasibility of goethite as a photocatalyst was evaluated. The highest removal efficiency of the process was achieved at a goethite dose of 0.05 g/L. Based on the comparison of oxidation efficiencies of arsenite between two light sources, the apparent performance of UV LED was inferior to that of UV lamp. However, when the results were appraised on the basis of their emitting UV irradiation, the higher performance was achieved by UV LED than by UV lamp. This study demonstrates that environmentally friendly process of goethite-catalytic photo-oxidation without any addition of foreign catalyst is feasible for the reduction of arsenite in groundwater containing naturally-occurring goethite. In addition, this study confirms that UV LED can be used in the photo-oxidation of arsenite as an alternative light source of UV lamp to remedy the drawbacks of UV lamp, such as long stabilization time, high electrical power consumption, short lifespan, and high heat output requiring large cooling facilities.

• Journal of Korean Society on Water Environment
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• 제29권2호
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• pp.204-211
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• 2013

In this study, the deriving optimum conditions for decolorization of Acid Orange II solution was carried using $TiO_2$ advanced oxidation process. After that, on base of the deriving results, the range of dye concentration was estimated. In addition, acute toxicity test was also carried to assess toxicity unit according to decolorization and TOC removal. In case of the blockage of light, 20 mg/L of dye solution, and 0.5 g $TiO_2$, the effect of decolorization at pH 3 was larger than at pH 6 and 10, so it was shown that decolorization is dependent on pH. The use of 5 g $TiO_2$ showed best performance of decolorization, but that of 3 g $TiO_2$ was chosen to optimum condition in considering of economical aspects. Four light sources, sun, fluorescent lamp, BLB lamp, and UV-B lamp, were used and decolorization was 99.4% and 100% at 50 mg/L, 98.6% and 99.7% at 100 mg/L for sun and UV-B lamp, respectively. In spite of the optimum condition of decolorization at pH 3, the evaluation of acute toxicity test showed highly toxic. In conclusion, although the optimum treatment of dye solution is performed, water ecology can be polluted in discharging it into water system. Therefore, it is needed to study of water ecological system with dye water treatment, and it takes all the circumstances into consideration.

• Polymer(Korea)
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• 제33권5호
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• pp.413-419
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• 2009

As the refractive index of the prism layer becomes higher, the optical performance of the prism sheet gets better and the efficiency of the LCD backlight unit is improved. In order to increase the refractive index of the prism layer, the ultraviolet curing type resins were prepared by mixing high refractive index materials containing aromatic groups and the multi-functional reactive diluents. By using 9,9-bis [4-(2-acryloyloxyethoxy)phenyl] fluorene, the refractive index of the prism layer was increased up to 1.58 and the brightness of the backlight unit was improved. Since the light source used in the backlight unit caused the yellowing in the prism sheet and deteriorated the brightness accordingly, the hindered amine light stabilizer was used to improve the yellowing resistance successfully.

• Advances in nano research
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• 제12권4호
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• pp.415-426
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• 2022

Nickel substituted cobalt-zinc ferrite nanoparticles with composition Co_0.5Zn_0.5Ni_xFe_2-xO₄ (x = 0.25, 0.5, 0.75, 1.0) were synthesized using a wet chemical method named citrate precursor method. Various characterizations of the prepared nanoferrites were done using X-ray powder diffractometry (XRD), Scanning electron microscopy (SEM), UV visible spectroscopy and Fourier transform spectroscopy technique (FT-IR). XRD confirmed the formation of cubic spinel structure of the samples with single phase having one characteristic peak at (311). The value of optical band gap (E_g) was found to decrease with Ni substitution and have values in the range 2.30eV to 1.69eV. A Fenton-type system was created by photocatalytic activity using source of visible light for removal of methylene blue dye. Observations revealed increase in the degradation of methylene blue dye with increasing nickel content in the samples. The degradation percentage was increased from 77.32% for x = 0.25 to 90.16% for x = 1.0 in one hour under the irradiation of visible light. Also, the degradation process was found to have pseudo first order kinetics model. Hence, it can be observed that synthesized nickel doped cobalt-zinc ferrites have good capability for water purification and its degradation efficiency enhanced with increase in nickel concentration.