• Textile Coloration and Finishing
• /
• v.14 no.2
• /
• pp.1-8
• /
• 2002

Cotton fabrics dipped in cationic agent(3-chloro-2-hydroxypropyl trimethyl ammonium chloride) were irradiated with deep Ultra Violet Rays(UV), in the region of UV-C using the low pressure mercury lamp. The chemical changes of cationized cotton fabric surfaces were investigated by FT-IR analysis. The dyeabilities of the irradiated portions were investigated by dyeing with acid dyes. Deep UV(UV-C) irradiation broke O-H bonds in cotton fiber and oxidized the fibers. The dyeability of the UV irradiated portion were different from that of the portion not irradiated. Various pattern were gained from one bath dig dyeing by pattern mask. The tensile strengths of cotton fabrics were decreased in the UV irradiated portion. Washing fastness of cotton dyeings were good about 3∼4 grade and light fastness were fair about 2∼3 grade.

• Journal of Korean Society of Water and Wastewater
• /
• v.12 no.3
• /
• pp.55-64
• /
• 1998

The degradation efficiency of chlorophenolic compounds in $TiO_2/H_2O_2$ combined system was compared with that of in $TiO_2$ sole system. As a result, the addition of hydrogen peroxide in photocatalytic oxidation reaction greatly enhanced the degradation efficiency of chlorophenolic compounds due to the availability of the hydroxyl radical formed on the $TiO_2$ surface. The hydrogen peroxide under UV illumination produces hydroxyl radicals that appear to be another source of hydroxyl radical formation. These results indicated the $TiO_2/H_2O_2$ combined system shows higher degradation efficiency than the $TiO_2$ sole system. Compared to another oxidation reaction, hydrogen peroxide assisted photocatalytic oxidation is more promising in practical aspect.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
• /
• v.23 no.2
• /
• pp.67-74
• /
• 2017

In this work, the effects of nano $TiO_2$ on functionality and stability of low density polyethylene (LDPE) composite films were investigated for food packaging application. LDPE-nano $TiO_2$ composite films were prepared with various $TiO_2$ contents (0, 0.5, 1.0, 3.0 and 5.0wt%) by melt-extrusion and their basic properties such as crystallinity, chemical bonds and surface morphology were examined by XRD, FTIR and SEM. Ultraviolet (UV) light barrier property of as-prepared LDPE-nano $TiO_2$ composite films was also studied and the presence of nano $TiO_2$ resulted in significant improvement of UV light barrier compared to the pure LDPE film. To evaluate influence of nano $TiO_2$ on LDPE properties required as packaging material, thermal, mechanical, gas barrier and optical properties of LDPE-nano $TiO_2$ composite films were characterized with various analytical techniques including TGA, UTM, OTR, WVTR and UV-vis spectroscopy. As a result, except optical property of LDPE, no significant effects were found in other properties. Opacity of pure LDPE was greatly increased with increasing concentration of nano $TiO_2$.

• Proceedings of the Membrane Society of Korea Conference
• /
• 1997.10a
• /
• pp.77-78
• /
• 1997

1. 서론 : Polyimide는 내열성과 기계적, 화학적 특성이 다른 고분자막에 비해 뛰어나며 선택도 또한 비교적 높기 때문에($\alpha$= 3-7) 최근 많은 연구가 대상이 되고 있다. 그러나 trade-off현상으로 알려진 바와 같이 선택도가 우수한 고분자 재료는 투과계수가 떨어지고 투과계수가 높은 고분자 재료는 낮은 선택도를 갖고 있기 때문에 보다 광범위한 분야에 실용적인 막으로 사용하기 위해서는 이를 개선하는 연구가 필요하다. 최근의 연구는 높은 투과계수와 선택도를 가진 새로운 고분자 재료의 합성에 관한 연구, 뛰어난 투과계수를 가지고 있지만 선택도가 낮은 고분자막을 대상으로 여러가지 수식방법을 이용하여 투과계수를 감소시키지 않으면서 동시에 선택도를 향상시키기 위한 연구, 우수한 화학적 특성과 선택도를 가진 물질을 대상으로 복합막이나 비대칭막으로 만들어 투과 저항을 극소화시키기 위한 연구 등의 방향으로 진행되고 있다. 본 연구는 Polyimide중 가장 큰 투과계수를 가진 것으로 보고된 6FDA-p-TeMPD막(P$_{O_2}$ = 122Barrer, $\alpha$$_{O_2/N_2}$ = 3.4)을 제조하여 분리 투과 특성을 향상시키려는 목적으로 UV처리를 하고 UV조사 시간과 강도(Intensity)를 변수로 투과 특성을 조사하여 가장 뛰어난 투과 특성을 나타내는 최적조건을 찾고자 하였다.

• Journal of Industrial and Engineering Chemistry
• /
• v.67
• /
• pp.486-496
• /
• 2018

Bimetallic Pd@Ni nanostructure exhibited enhanced co-catalytic activity for the selective hydrogenation of benzaldehyde compare to their monometallic counterparts. Impregnation of these mono/bimetallic nanostructures on mesoporous $TiO_2$ leads to several surface modifications. The bimetallic PNT-3 ($Pd_3@Ni_1/mTiO_2$) exhibited large surface area ($212m^2g^{-1}$), and low recombination rate of the charge carriers ($e^--h^+$). The hydrogenation reaction was analyzed under controlled experiments. It was observed that under UV-light irradiations and saturated hydrogen atmosphere the bimetallic PNT-3 photocatalyst display higher rate constant $k=5.31{\times}10^{-1}h^{-1}$ owing to reduction in the barrier height which leads to efficiently transfer of electron at bimetallic/$mTiO_2$ interface.

• International Journal of Oral Biology
• /
• v.46 no.3
• /
• pp.105-110
• /
• 2021

The physicochemical properties of crystalline titanium dioxide nanoparticles (TiO₂ NPs) were investigated by comparing amorphous (amTiO₂), anatase (aTiO₂), metaphase of anatase-rutile (arTiO₂), and rutile (rTiO₂) NPs, which were prepared at various calcination temperatures (100℃, 400℃, 600℃, and 900℃). X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses confirmed that the phase-transformed TiO₂ had the characteristic features of crystallinity and average size. The surface chemical properties of the crystalline phases were different in the spectral analysis. As anatase transformed to the rutile phase, the band of the hydroxyl group at 3,600-3,100 cm^-1 decreased gradually, as assessed using Fourier transform infrared spectroscopy (FT-IR). For ultraviolet-visible (UV-Vis) spectra, the maximum absorbance of anatase TiO₂ NPs at 309 nm was blue-shifted to 290 nm at the rutile phase with reduced absorbance. Under the electric field of capillary electrophoresis (CE), TiO₂ NPs in anatase migrated and detected as a broaden peak, whereas the rutile NPs did not. In addition, anatase showed the highest photocatalytic activity in an UV-irradiated dye degradation assay in the following order: aTiO₂ > arTiO₂ > rTiO₂. Overall, the phases of TiO₂ NPs showed characteristic physicochemical properties regarding size, surface chemical properties, UV absorbance, CE migration, and photocatalytic activity.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2012.05a
• /
• pp.81.1-81.1
• /
• 2012

나노임프린트 리소그라피(Nano-Imprint Lithography, NIL) 기술은 기판위의 resin을 나노구조물이 각인된 스탬프로 눌러서 나노구조물을 형성하는 기술로, 경제적이고 효과적으로 나노구조물을 제작할 수 있는 기술이다. 그중에서도 UV 기반의 나노임프린트(UV-NIL) 기술은 resin을 투명한 스탬프로 누른뒤 UV로 경화시켜 나노구조물을 형성하는 기술로써 고온, 고압($140{\sim}180^{\circ}C$, 10~30bar)이 필요한 가열식 나노임프린트 기술에 비해 상온, 상압($20^{\circ}C$, 1bar)에서도 구조물 형성이 가능하여 다층구조 형성에 적합하다. 연속적인 임프린팅 공정에 의해 resin이 quarz 스탬프에 잔류하여 패터닝에 결함을 유발하게 되므로 오염물을 제거하기 위한 세정공정이 필요하다. 하지만 UV에 의해 경화된 resin은 cross-linking을 형성하여 화학적인 내성이 증가하게 되므로 제거하기가 어렵다. 현재는 resin 제거를 위한 세정공정으로 SPM($H_2SO_4/H_2O_2$) 세정이 사용되고 있는데 세정시간이 길고 세정 후에 입자 또는 황 잔유물이 남으며 많은 유해용액 사용의 문제점이 있어 효과적으로 resin을 제거할 세정공정이 필요한 상황이다. 본 연구에서는 친환경적인 UV 세정 및 오존수 세정공정을 적용하여 경화된 resin을 제거하는 연구를 진행하였다. 실험샘플은 약 100nm 두께의 resin을 증착한 $1.5cm{\times}1.5cm$ $SiO_2$ 쿠폰 wafer를 사용하였으며, UV 및 오존수의 처리시간을 달리하여 resin 제거효율을 평가하였다. ATR-FTIR 장비를 사용하여 시간에 따른 resin의 두께를 측정한 결과, UV 세정으로 100nm 높이의 resin중에 80nm의 bulk resin이 단시간에 제거가 되었고 나머지 20nm의 resin thin film은 오존수 세정으로 쉽게 제거되는 것을 확인 하였다. 또한 표면에 남은 resin residue와 particle을 제거하기 위해서 SC-1 세정을 진행하였고 contact angle과 optical microscope 장비를 사용하여 resin이 모두 제거된 것을 확인하였다.

• Korean Journal of Remote Sensing
• /
• v.29 no.3
• /
• pp.325-329
• /
• 2013

This present study describes an application of UV scanning spectrometer $O_4$ data for retrieval of aerosol vertical profiles in Seoul during the measurement period that includes two Asian dust event days. The results show large variations of aerosol load in vertical and temporal scales. Large variations in aerosol were observed at 1 km in height during the daytime in the measurement period when the Asian dust events took place. The aerosol load, however, was found to be largest at the surface compared to those retrieved at the higher atmospheric layers. The results also clearly identified the diurnal patterns of aerosol vertical distributions. The aerosol load was high in the morning and noon whereas it was low in the afternoon. This study demonstrates that UV scanning spectrometer observations of the oxygen dimer can serve as a potential method for determination of atmospheric aerosol vertical distributions and optical properties.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.178.1-178.1
• /
• 2014

본 연구에서는 RF스퍼터링법에 의하여 유리기판에 NiO를 40 nm만큼 증착시킨후, 30분 동안 각각 상온, $100^{\circ}C$, $200^{\circ}C$, $300^{\circ}C$, $400^{\circ}C$로 후 열처리 하였다. 박막의 전자적, 광학적 특성은 XPS (X-ray Photoelectron Spectroscopy), REELS (Reflection Electron Energy Loss Spectroscopy)와 UV-Spectrometer를 이용하여 =측정하였고, Hall Effect를 이용하여 전기적 특성을 측정하였다. XPS측정결과, $400^{\circ}C$ 후 열처리 한 NiO박막은 NiO 결합인 Ni2+가 줄어 들면서 금속 결합인 Ni0가 증가하면, 상온에서 띠틈이 4.0eV, 3.4eV로 줄어드는 것을 REELS로 확인 했다. 이 값은 UV-Spectrometer를 이용한 광학적 띠틈과 같음을 보였다. Hall Effect측정 결과 $400^{\circ}C$ 후 열처리한 샘플에서 P-type에서 N-type으로 바뀜을 보였으며, 비저항이 낮아지는 경향을 보였다. UV-Spectrometer를 이용한 광학적 특성을 측정해본 결과, 가시광선영역인 380 nm~780 nm에서의 투과율이 75%이상으로 투명전자소자로의 응용이 가능하다는 것을 보여 주었다.

• Journal of the Semiconductor & Display Technology
• /
• v.20 no.2
• /
• pp.1-5
• /
• 2021

Ultraviolet (UVA)-emissive BaSiO₃:Ce³⁺ phosphor was astonishingly reproducible by vacuum-sintering at a high temperature through a simple solid-state reaction method. It was conveniently formed in BaSiO₃ phases. The compound showed the UVA emission and the UV-VUV excitation due to 5d-4f transitions from Ce³⁺ ions: emission peak at 380 nm with a 56 nm width. Its temperature dependence and vacuum UV excitability were examined for practical application as an excimer discharge lamp, which showed the high thermal stability (80% at 100℃) and the strong VUV excitations at 145 nm and 172 nm.