• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.1
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• pp.15-18
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• 2009

To enhance near UV-visible absorption region and to applied phosphor convert-white LEOs (PC-WLEDs), a red phosphor composed of ${Y_2}{SiO_5}:\;EU^{3+}$, $Bi^{3+}$ compounds was prepared by the conventional solid-state reaction. The photoluminescence (PL) shown that samples were excited by near UV light 395 nm for measurement of PL spectra. Emission spectra of samples have shown red emissions at 612 nm ($^5D_0{\to}^7F_2$). The enhanced near $UV{\sim}$ visible excitation spectrum with a broad band centered at 258 nm and 282 nm originated in the transitions toward the charge transfer state (CTS) due to the $Eu^{3+}-Bi^{3+}-O^{2-}$ interaction. The other excitation band at $350\;nm{\sim}480\;nm$, corresponding to the transitions $^7F_0{\to}^5L_9$ (364 nm), $^7F_0{\to}^5G_3$ (381 nm), $^7F_0{\to}^5L_6$ (395 nm), $^7F_0{\to}^5D_3$, (415 nm) and $^7F_0{\to}^5D_2$ (466 nm), occurred due to enhanced the f-f transition increasing $Bi^{3+}$ and $Eu^{3+}$ ions. The PL intensity increased with increased as concentration of $Bi^{3+}$ and the emission intensity becomes with a maximum at 0.125 mol.

• Korean Chemical Engineering Research
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• v.59 no.4
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• pp.584-595
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• 2021

In this study, the correlation between operating stages of waste air-treating system composed of two alternatively-operating UV/photocatalytic reactors, and the deactivation of photocatalyst used in each operating stage, was investigated by instrumental analysis thereon. The repeated deactivation and subsequent re-generation of photocatalyst used in the waste air treating system of previous investigation performed by Lee and Lim (Korean Chem. Eng. Research, 59(4), 574-583(2021)), were characterized on virgin photocatalyst-carrying porous SiO₂ media (A4), used photocatalyst-carrying porous SiO₂ media (A1, A2 and A3) collected from the corresponding photocatalytic reactor upon 1^st, 2^nd, and 3^rd run, respectively, regenerated photocatalyst-carrying porous SiO₂ media upon 1 time-run (AD1) and 3 times regenerated photocatalyst-carrying porous SiO₂ media upon 3 time-runs (AD3) by instrumental analysis including BET analysis, SEM, XPS, SEM-EDS and FT-IR. As a result, the proper regeneration-temperature for deactivated photocatalyst to be regenerated several times (more than 3 times), was suggested below 200 ℃. Such temperature of deactivated photocatalyst-regeneration was almost consistent to the one, according to BET analysis, at which tiny nano-pores blocked by adsorbed ethanol-oxidative and degraded intermediates (AEODI), were regenerated to be reopened through almost complete mineralization of AEODI. In particular, the results of XPS analysis indicated an incurrence of insignificant deactivation of photocatalysis upon 1^st run of UV/photocatalytic reactor (A or C) of the previous investigation. In addition, the results of XPS analysis were consistent with the experimental results of the previous investigation in that 1) deactivation of photocatalyst incurred during 2^nd run of the UV/photocatalytic reactor (A or C) resulted in decreased removal efficiency, by ca. 5% and 5%, of ethanol and hydrogen sulfide, respectively, compared with its 1^st run; 2) there was insignificant difference between the removal efficiencies of its 2^nd run and 3^rd run. Furthermore, the removal efficiencies of ethanol and hydrogen sulfide for hypothetical 4^th run of photocatalytic reactor in the previous investigation, using AD3, were expected to decrease, compared with its 3^rd run, by much more than those for 2^nd run in the previous investigation did, compared with its 1^st run.

• Journal of Korean Society for Atmospheric Environment
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• v.25 no.3
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• pp.211-218
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• 2009

Feasibility study of using $Ti0_2$ mist generated by ultrasonic atomization for photocatalytic degradation of gaseous toluene was attempted in this study. For this, the photocatalytic reactor consisting of mist generator and photo-reactor was designed. Most of experimental results showed that steady state reached about 30 minutes after the start of experiments. The effects of $Ti0_2$ concentration, toluene concentration, and UV wavelength on toluene removal ratio were investigated. It was found that the highest removal efficiency was obtained when $Ti0_2$ concentration was 0.6 g/L in slurry. At this condition, it was found that the toluene removal efficiency increased as toluene concentration in feed decreased. In order to investigate the effect of UV wavelength, experiments were carried out using three UV lamps with different UV wavelength. The results showed that the highest removal efficiency was achieved when the lamp with the shortest wavelength were employed.

• Journal of Animal Environmental Science
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• v.7 no.3
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• pp.191-195
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• 2001

This research was carried out to investigate the effect of ozone treatment to improve the livestock drinking water quality. Ozone concentration treated was 18.5~36.5ppm in each system. PH and dissolved oxygen(DO) concentration in drinking water was increased by ozone and ozone+anion treatment. But there was no difference in UV used for drinking water treatment. Oxidation and deduction Potential(ORP) was increased while ozone was treated. Colony Forming Unit(CFU) of E. coli 0.8:$H^-$, Salmonella typhimurium, Staphylococcus aureus was decreased after 30 minute to 1 hour ozone and UV treatment.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.03a
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• pp.50-50
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• 2011

발수가공은 섬유표면에 낮은 표면에너지 물질을 도포하여 섬유제품에 적심 저항성을 부여하는 것으로 일반적인 방법으로는 불소계 고분자 물질을 포함한 가공제액을 부여하고 열에너지원을 사용하여 섬유 표면에 경화하여 고착시키고 처리온도는 $150{\sim}170^{\circ}C$의 범위에서 수 분 처리하지만 처리시간을 증가하면 섬유에 황변을 일으킬 수 있고 직물의 한 면에만 발수성을 구현하기가 어렵다. 피부와 접촉하는 부위에서의 불필요한 발수성은 땀 흡수저하, 알러지 발생 우려 등 쾌적성 저하 요인이 될수 있어 스포츠, 레저 의류 분야에서는 섬유제품의 일면만을 발수처리 하는 가공이 필요되어진다. 편면 발수가공을 위한 선행기술로는 상하 중 하나의 롤러에만 발수제를 묻혀 섬유제품의 일면에만 발수가공을 하는 것과 분사기로 발수제를 섬유제품의 일면에 도포하는 것 등이 있다. 하지만 일면에 처리된 발수제가 반대면으로 침투하거나 균일한 발수처리가 되지 않는 등의 문제점이 있고 발수제의 농도증가 및 증점제를 사용하여 점도를 증가시켜야하기 때문에 발수처리의 균일성 및 내구성 있는 편면발수공정이 어려운 단점이 있다. 본 연구에서는 UV경화가 가능한 불소계 발수제와 물에 용해되는 광개시제가 첨가된 수용액을 PET직물에 패딩하고 UV로 경화하여 양면 모두 발수성을 부여한 후 UV조사로 표면개질하여 표면친수성을 증가시켜 양 면의 발수성을 조절하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.1022-1025
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• 2005

The effect of substrate surface to the formation of ZnO nanostructures has been investigated using Si (111), $Al_2O_3$(C-plane) $Al_2O_3$(A-plane), and $Al_2O_3$(R-plane) substrates. The growth temperature was controlled from 500$^{\circ}C$ ${\sim}$ 600$^{\circ}C$, and the luminescence properties were investigated by a series of photoluminescence (PL) measurements at the elevating temperatures. ZnO nanostructures grown on Si substrate show strong UV emission intensity along with green emission positioned at 3.22 eV and 2.5 eV, respectively. However, green emission was not observed from the ZnO nanostructures grown on $Al_2O_3$ substrates. It is explained in terms of the difference of the surface energy between Si and $Al_2O_3$. Also, the origin of UV emissions has been discussed by using the temperature-dependent PL. The distinction of the PL spectra is interpreted in terms of the difference of the impurity included in the nanostructures.

• Clean Technology
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• v.23 no.1
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• pp.95-103
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• 2017

In this study, $ATiO_3$ (A = Ca, Sr, Ba) perovskite, which is the widely known for non $TiO_2$ photocatalysts, were synthesized using sol-gel method. And Ni was added at the A site of $ATiO_3$ by using that it is easy to incorporate. The physicochemical characteristics of the obtained $ATiO_3$ and Ni-$ATiO_3$ particles were confirmed using the X-ray diffraction (XRD) UV-visible spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), the $N_2$ adsorption-desorption isotherm measurement, and X-ray photoelectron spectroscopy (XPS). The $H_2$ was produced using the photolysis of MeOH. Using the Ni-$ATiO_3$ photocatalysts, $H_2$ production was higher than using the $ATiO_3$ photocatalysts. Especially, $273.84mmolg^{-1}$ $H_2$ was produced after 24 h reaction over the Ni-$SrTiO_3$. Also in the water (0.1 M KOH) with the Ni-$SrTiO_3$, $H_2$ production was $961.51mmolg^{-1}$ after 24 h reaction.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.373-373
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• 2010

광촉매능을 갖는 $TiO_2$는 국내외적으로 많은 연구가 진행되고 있다. 빛의 조사로 발생하는 다양한 물리 화학적 촉매특성이 환경정화 뿐만 아니라 및 에너지 흡수차단 기능도 갖고 있어 최근 주목을 받고 있다. 응용분야로 초친수성 유리제품, 필터, 살균기능의 의료용 부품소재, 고효율 수소생산 및 태양전지 등에 활용성이 커서 친환경에너지 소재로 각광을 받고 있다. 본 연구에서는 초친수성 자동차의 사이드미러 개발을 위해 유리표면에 초친수성 $TiO_2$를 코팅하 고 그의 특성을 평가하였다. 특히, 이종밴드갭을 갖는 복합구조 $TiO_2/Cr_2O_3$/Cr 박막을 스퍼터링법으로 증착하여 중간층인 $Cr_2O_3$의 역할을 고찰하였다. 제조된 박막의 결정구조는 thin film형 X-선회절기(XRD)를 사용하여 분석하였으며, 박막의 표면 미세구조는 FE-SEM(Field Emission Scanning Electron Microscope)와 AFM(Atomic Force Microscope)으로, 화학구조는 XPS(X-ray Photoelectron Spectroscope)로 분석하였다. 친수성 평가는 실온 분위기에서 접촉각 측정기(Topcon-UVR2)를 사용하여 평가 하였으며 이때 조사되는 UV는 파장이 365nm이다. $Cr_2O_3$(비정질)/Cr박막위에 제조된 $TiO_2$ 박막은 균일한 anatase-$TiO_2$가 성장했으나, Cr, $Cr_2O_3$(결정질)박막위에 제조 된 $TiO_2$ 박막은 anatase상과 rulile상이 혼합된 형태로 성장하였다. $TiO_2$/Cr, $TiO_2/Cr_2O_3$(비정질)/Cr, $TiO_2/Cr_2O_3$(결정질)/Cr박막은 UV조사 1시간 만에 $10^{\circ}$ 이하의 초친수성을 나타내었다. 이종 밴드갭을 갖는 $TiO_2/Cr_2O_3$(비정질)/Cr박막은 40시간까지 친수성을 유지하는 결과를 나타냈다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.11a
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• pp.340-340
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• 2015

상지 절단 장애인들을 위한 미관형 의수는 95% 이상의 시장 보급률을 보인다. 하지만 외부 형상 향상에만 연구 초점이 맞추어져 있어 많은 장애인들이 의수를 착용할 때 차가운 표면으로 인해 이질감을 느낀다. 이로 인해 의수 제작 업체 및 절단 장애인들은 착용 시 이질감이 적은 의수의 보급을 희망하고 있다. 그러므로 본 연구에서는 인체와 유사한 온도를 발생시켜 이질감을 감소시키는 의수를 개발하기 위해 유연 기판인 TPU (Temperature Polyurethane)와 PET (Polyethylene terephthalate) 위에 상용 silver nano paste를 3D 프린터로 인쇄하였으며, UV 표면처리를 사용하여 단시간 내에 낮은 저항과, 높은 회로 접착강도를 갖는 회로를 개발 하였다.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.2
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• pp.313-319
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• 2012

This study investigated the relative degradation of commonly known endocrine-disrupting compounds such as bisphenol A (BPA) and 17${\beta}$-estradiol (E2) using ultrasound (US) and pulsed ultraviolet (PUV) in water. The removal efficiency of BPA and E2 was determined as a function of generating power and $H_{2}O_{2}$ production. The ultrasound and PUV irradiation of the aqueous solution was performed in 3 L and 90 L stainless reactor at a constant temperature of $20^{\circ}C$ with an applied power of 200 W and 2000 W, respectively. The removal of BPA and E2 by US and PUV varied with catalysts. The experiments were conducted under the following conditions: total operating time, 30 min; initial concentration, 1 uM. In the case of E2 (10 min), % removal was 92.5/95.8/87.6/82.4, while % removal of BPA (10 min) was 62.3/82.3/91.1/67.0/64.3 in various conditions (PUV, $PUV+H_2O_2$, PUV+wire mesh, $PUV+TiO_2$ coated wire mesh), respectively.