• 공업화학
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• 제30권6호
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• pp.694-697
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• 2019

최근에 이산화티탄 분말을 나노입자로 제조하거나 결정성을 향상하기 위해 1차원 구조인 nanowire, nanotube, 3차원 구조인 mesoporous 구형으로 생산하여 차단율과 반사율을 통한 광 전극 소재로의 활용과 피부 광 노화 방지에 더욱 효율적으로 적용할 수 있는 연구가 진행되고 있다. 본 연구에서는 n-alcohol을 용매로 사용하여 높은 결정성을 갖는 이산화티탄 나노 졸을 합성하였다. 합성된 이산화티탄 나노 졸은 FE-SEM과 XRD을 통해 결정성을 확인하였고, 자외선 차단율을 확인하기 위해서 UV-Vis로 투과율을 확인했다. 또한. 용매에 따른 결정성을 확인하기 위하여 부탄올, 프로판올, 에탄올을 이용하여 각각을 제조하였고, 용매에 따른 차이를 비교하였다. 입자크기는 200~250 nm로 합성되었으며 광학적 투과율은 UVB, UVA 범위에서 높은 차단율을 보이고, 550 nm 파장에서 높은 투과율을 보여 태양전지의 광전 변환 효율 향상과 소량 사용으로도 제품의 자외선 차단 효율을 높일 수 있을 것으로 기대된다.

• 한국전기전자재료학회논문지
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• 제31권4호
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• pp.267-271
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• 2018

A high directivity TIR (total internal reflection) lens in the UV-A region was designed using a silicone resin, and a UV light source module with a maximum irradiation density of $150mW/cm^2$ was fabricated. The beam angle of the TIR lens was designed to be $8.04^{\circ}$ and the maximum diameter of the TIR lens was Ø13.5. A silicone resin having a UV transmittance of 93% and a refractive index of 1.4 at a wavelength of 365 nm was used, and the lens was manufactured using an aluminum mold, from which silicone could be easily released. The module was fabricated in a metal printed circuit board of COB (chip on board) type using a $0.75{\times}0.75mm^2$ UV chip. A jig was used to adjust the focal length between lens and chip and to fix the position of the lens. The optical characteristics such as illumination distributions of the lens and module were designed using 'LightTools' optical simulation software. The heat dissipation system was designed to use a forced-air cooling method using a heat-sink and fan.

• 한국표면공학회지
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• 제48권2호
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• pp.50-55
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• 2015

$Al_2O_3$ thin films were deposited on the moth eye anti-reflective nanostructured polycarbonate films by atomic layer deposition (ALD) techniques. Without ALD-$Al_2O_3$ thin films, moth eye anti-reflective nanostructured films had a high optical transmittance of 95.47% at a wavelength of 550 nm and a very poor hardness of 0.1381 GPa. With increasing the thickness of $Al_2O_3$ thin films from 5 to 25 nm, the transmittance of moth eye anti-reflective nanostructured films was gradually decreased from 94.94 to 93.12%. On the other hand, the hardness of the films was greatly increased from 0.3498 to 0.7806 GPa with increasing the thickness of $Al_2O_3$ thin films. This result shows that ALD thin films can be applied to improve mechanical properties with an adequate optical transmittance of the conventional moth eye anti-reflection nanostructure films.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.188-188
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• 2012

Graphene, with its unique physical and structural properties, has recently become a proving ground for various physical phenomena, and is a promising candidate for a variety of electronic device and flexible display applications. Compared to indium tin oxide (ITO) electrodes, which have a typical sheet resistance of ${\sim}60{\Omega}$/sq and ~85% transmittance in the visible range, the chemical vapor deposition (CVD) synthesized graphene electrodes have a higher transmittance in the visible to IR region and are more robust under bending. Nevertheless, the lowest sheet resistance of the currently available CVD graphene electrodes is higher than that of ITO. In this study, we report a creative strategy, irradiation of microwave at room temperature under vacuum, for obtaining size-homogeneous gold nano-particle doping on graphene. The gold nano-particlization promoted by microwave irradiation was investigated by transmission electron microscopy, electron energy loss spectroscopy elemental mapping. These results clearly revealed that gold nanoparticle with ${\geq}30$ nm in mean size were decorated along the surface of the graphene after microwave irradiation. The fabrication high-performance transparent conducting film with optimized doping condition showed a sheet resistance of ${\geq}100{\Omega}$/sq. at ~90% transmittance. This approach advances the numerous applications of graphene films as transparent conducting electrodes.

• Transactions on Electrical and Electronic Materials
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• 제16권6호
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• pp.303-307
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• 2015

Multilayered films of ITO (In₂O₃:SnO₂ = 9:1)/SiO₂ were deposited on soda-lime glass by RF/DC magnetron sputtering at 500℃ to improve the energy conversion efficiency of dye-sensitized solar cells (DSSCs). The light absorption of the dye was improved by decrease in light reflectance from the surface of the DSSCs by using an ITO film. In order to estimate the optical characteristics and compare them with experimental results, a simulation program named EMP (essential macleod program) was used. EMP results revealed that the multilayered thin films showed high transmittance (approximate average transmittance of 79%) by adjusting the SiO₂ layer thickness. XRD results revealed that the ITO and TiO₂ films exhibited a crystalline phase with (400) and (101) preferred orientations at 2 θ = 26.24° and 35.18°, respectively. The photocurrent-voltage (I-V) characteristics of the DSSCs were measured under AM 1.5 and 100 mW/cm² (1 sun) by using a solar simulator. The DSSC fabricated on the ITO film with a 0.1-nm-thick SiO₂ film showed a Voc of 0.697 V, J_sc of 10.596 mA/cm² , FF of 66.423, and calculated power conversion efficiency (η_AM1.5) of 5.259%, which was the maximum value observed in this study.

• 한국전기전자재료학회논문지
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• 제27권11호
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• pp.760-765
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• 2014

MgZnO has attracted a lot of attention for flexible device. In the flexible substrate, the crystal structure of the thin films as well as the surface morphology is not good. Therefore, in this study, we studied on the effects of the oxygen pressure on the structure and crystallinity of $Mg_{0.3}Zn_{0.7}O$ thin films deposited on PES substrate by using pulsed laser deposition. We used X-ray diffraction and atomic force microscopy in order to observe the structural characteristics of $Mg_{0.3}Zn_{0.7}O$ thin films. The crystallinity of $Mg_{0.3}Zn_{0.7}O$ thin films with increasing temperature was improved, Grain size and RMS of the films were increased. UV-visible spectrophotometer was used to get the band gap energy and transmittance. $Mg_{0.3}Zn_{0.7}O$ thin films showed high transmittance over 90% in the visible region. As increased working pressure from 30 mTorr to 200 mTorr, the bandgap energy of $Mg_{0.3}Zn_{0.7}O$ thin film were decreased from 3.59 eV to 3.50 eV.

• 전기학회논문지
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• 제67권1호
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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.

• The Journal of Advanced Prosthodontics
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• 제5권4호
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• pp.464-470
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• 2013

PURPOSE. The aim of this Fourier transform infrared (FTIR) spectroscopic study was to measure the degree of conversion (DC) of dual-cured resin cements light-irradiated through zirconia ceramic disks with different thicknesses using various light-curing methods. MATERIALS AND METHODS. Zirconia ceramic disks (KT12) with three different thicknesses (1.0, 2.0, and 4.0 mm) were prepared. The light transmittance of the disks was measured using ultraviolet visible near-infrared spectroscopy. Four different light-curing protocols were used by combining two curing light modes (Elipar TriLight (standard mode) and bluephase G2 (high power mode)) with light-exposure times of 40 and 120 seconds. The DCs of the two dual-cured resin cements (Duo-Link and Panavia F2.0) light-irradiated through the disks was analyzed at three time intervals (3, 7, and 10 minutes) by FTIR spectroscopy. The data was analyzed using repeated measures ANOVA (${\alpha}$=.05).Two-way ANOVA and Tukey post hoc test were used to analyze the 10 minute DC results. RESULTS. The 1.0 mm thick disk exhibited low light transmittance (<25%), and the transmittance decreased considerably with increasing disk thickness. All groups exhibited significantly higher 10 minute DC values than the 3 or 7 minute values (P<.05), but some exceptions were observed in Duo-Link. Two-way ANOVA revealed that the influence of the zirconia disk thickness on the 10 minute DC was dependent on the light-curing methods (P<.001). This finding was still valid even at 4.0 mm thickness, where substantial light attenuation took place. CONCLUSION. The curing of the dual-cured resin cements was affected significantly by the light-curing technique, even though the additional chemical polymerization mechanism worked effectively.

• 한국융합학회논문지
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• 제10권12호
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• pp.177-181
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• 2019

본 연구는 광중합기의 청색광을 이용한 치과 치료과정에서 광중합기용 팁들과 보안경의 청색광 차단정도를 알아보기 위해, UV-Vis 스펙트로미터 기기에 광중합기용 팁들과 보안경들을 위치시키고 빛을 투과하여 측정한 결과를 비교 분석하였다. 분석결과, 분석에 사용한 4가지 종류의 광중합기용 팁들 모두 청색광 차단효과가 매우 우수한 것으로 나타났다. 보안경의 경우 붉은색 계열 보안경이 노란색 계열 보안경보다 광중합기용 팁들과 유사한 청색광 투과율을 보여 청색광 차단효과가 더 우수한 것으로 나타났다. 결과적으로 청색광 차단정도가 높은 광중합기용 팁 부착과 보안경 착용이 눈 보호를 위해 필요한 행위임을 추천한다. 이러한 행위는 눈에 대한 지속적인 자극과 피로감을 줄여줄 것이라 사료된다.

• 공업화학
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• 제10권4호
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• pp.603-607
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• 1999

Potassium iodide(KI)를 함유하는 poly(vinyl alcohol)(PVA) 필름의 산화공정에 의해 제조된 PVA-iodine 착제물(PVA_KI계)의 편광특성을 조사하였다. PVA-KI계 편광필름의 UV-visible 스펙트럼은 220 nm, 290~360 nm와 650 nm에서 $I^{-}$, $I{_3}{^-}$와 $I{_5}{^-}$ 발색단에 해당하는 흡수밴드를 각각 나타냈다. PVA-KI계 필름의 편광효율과 투과도는 산화시간, 연신비율, KI 농도 등에 크게 의존하였다. 제조된 편광필름은 99.5%와 45%의 높은 편광효율 및 투과도를 나타냈다. 특히 산화공정에 의해 제조된 편광필름의 열저항은 기존의 PVA-$I_2$계 편광필름에 비하여 뛰어났다. 이러한 결과는 PVA 편광필름의 산화공정의 차이에 기인된다고 생각된다.