• 한국표면공학회지
• /
• 제56권3호
• /
• pp.208-218
• /
• 2023

Photocatalysts are advanced materials which accelerate the photoreaction by providing ordinary reactions with other pathways. The catalysts have various advantages, such as low-cost, low operating temperature and pressure, and long-term use. They are applied to environmental and energy field, including the air and water purification, water splitting for hydrogen production, sterilization and self-cleaning surfaces. However, commercial photocatalysts only absorb ultraviolet light between 100 and 400 nm of wavelength which comprises only 5% in sunlight due to the wide band gap. In addition, rapid recombination of electron-hole pairs reduces the photocatalytic performance. Recently, studies on blackening photocatalysts by laser, thermal, and plasma treatments have been conducted to enhance the absorption of visible light and photocatalytic activity. The disordered structures could yield mid-gap states and vacancies could cause charge carrier trapping. Herein, liquid phase plasma (LPP) is adopted to synthesize Ag-doped black ZnO for the utilization of visible-light. The physical and chemical characteristics of the synthesized photocatalysts are analyzed by SEM/EDS, XRD, XPS and the optical properties of them are investigated using UV/Vis DRS and PL analyses. Lastly, the photocatalytic activity was evaluated using methylene blue as a pollutant.

• 보존과학회지
• /
• 제33권3호
• /
• pp.203-214
• /
• 2017

본 연구에서는 야외 플라스틱 작품에 많이 사용되고 있는 유리섬유강화플라스틱(FRP)을 대상으로 자외선에 의한 색도 및 광택도, 접촉각 변화, 적외선 분광분석을 통해 열화 특성을 확인하였으며, FRP의 열화를 예방하고자 자외선 차단 코팅제를 제조하여 코팅제의 성능 평가를 진행하였다. 자외선 열화 결과, FRP의 표면변화는 기공 이외에 다른 변화는 관찰되지 않았다. 색차는 열화 초기에 급격히 증가하였는데 이는 적외선 분광분석 결과와도 유사하였다. 광택도 및 접촉각의 경우 뚜렷한 변화는 확인되지 않았다. 코팅제 처리에 따른 특정한 표면 변화는 관찰되지 않았으나 색차 비교 결과, 미처리 시편보다 색 변화가 낮게 측정되어 변색 제어가 가능함을 확인하였다. 코팅제 도포 후 열화에 따른 광택도 및 접촉각 변화가 일부 관찰되었으나 자외선 차단 코팅제는 상대적으로 안정한 것으로 나타났다. 적외선 분광분석 결과, 화학적 변화가 미미함에 따라 코팅제가 일정 기간 동안 열화를 지연시키는 것으로 보인다. 본 연구를 통해 작품 재료로써 FRP의 자외선 열화 양상을 파악하였으며, 제조한 자외선 차단 코팅제의 성능 평가를 통해 야외 FRP 작품의 보존 방안으로써 적용 가능성을 확인하였다.

• 대한수의학회지
• /
• 제49권1호
• /
• pp.17-22
• /
• 2009

The effect of Bu-Zhong-Yi-Qi-Tang (BZYQT) on the changes of ultraviolet (UV) light B radiation-induced apoptotic sunburn cell (SBC) and epidermal ATPase-positive dendritic cell (DC) in SKH1- hr or ICR mouse were investigated. The mice were treated with UVB (200 mJ/$cm^2$) and were sacrificed 24 h later. BZYQT (50 mg/kg of body weight) or vehicle (saline) was given i.p. at 36 and 12 h before irradiation, and 30 min after irradiation or BZYQT cream (0.2%) or cream base (vehicle) was topically treated at 24 h and 15 min before irradiation, and immediately after irradiation. The skin of SKH1-hr mouse prepared from the back of untreated mice exhibited about 0.3 SBC/cm length of epidermis, and 24 h after UV irradiation, the applied areas show an increased number of SBCs. But the frequency of UVB-induced SBC formation was reduced by intraperitoneal injection of BZYQT extract (p < 0.01). The numbers of DC in normal ICR mouse were 628.00 ${\pm}$ 51.56 or 663.20 ${\pm}$ 62.58 per $mm^2$ of ear epidermis. By 1 day after UVB treatment, the number of ATPase-positive cells/$mm^2$ were decreased by 39.0% or 27.1% in i.p. or topical application group with vehicle. Treatment of BZYQT was associated with increase of 33.9% in i.p. group (p < 0.05) or 2.7% in topical application group in the number of ATPase positive cells compared with the irradiation control group. The results presented herein that BZYQT administration could reduce the extent of skin damages produced by UVB.

• Journal of Ginseng Research
• /
• 제30권4호
• /
• pp.194-198
• /
• 2006

The effects of red ginseng (RG) on the changes of ultraviolet (UV) light B radiation-induced apoptotic sun-burn cell (SBC) and epidermal ATPase-positive dendritic cell (DC) in SKH 1-hr or ICR mouse were investigated. The mice were treated with UVB ($200mJ/cm^2$) and were sacrificed 24 hours later. RG (50 mg/kg of body weight) or vehicle (saline) was given i.p. at 36 and 12 hours before irradiation, and 30 minutes after irradiation. RG cream (0.2%) or cream base (vehicle) was also topically treated at 24 hours and 15 minutes before irradiation, and immediately after irradiation. The skin of SKH 1-hr mouse prepared from the back of untreated mice exhibited about 0.3 SBC/cm length of epidermis, and 24 hours after UV irradiation, the applied areas show an increased number of SBCs. But the frequency of UVB-induced SBC formation was significantly reduced by intraperitoneal injection of RG extract. The numbers of DC in normal ICR mouse were $628.00{\pm}51.56\;or\;663.20{\pm}62.58\;per\;mm^2$ of ear epidermis. By 1 day after UVB treatment, the number of ATPase-positive $cells/mm^2$ were decreased by 39.0% or 27.1% in i.p. or topical application group with vehicle. The frequency of UVB ($200mJ/cm^2$)-induced DC decrease was reduced by treatment of RG as 31.3% in i.p. group and 22.4% in topical application group compared with the irradiation control group. The results presented herein that RG administration could reduce the extent of skill damages produced by UVB.

• Bulletin of the Korean Chemical Society
• /
• 제33권5호
• /
• pp.1491-1504
• /
• 2012

InP quantum dot (QD)-organosilicon nanocomposites were synthesized and their photoluminescence quenching was mainly investigated because of their applicability to white LEDs (light emitting diodes). The as-synthesized InP QDs are capped with myristic acid (MA), which are incompatible with typical silicone encapsulants. We have introduced a new ligand, 3-aminopropyldimethylsilane (APDMS), which enables embedding the QDs into vinyl-functionalized silicones through direct chemical bonding. The exchange of ligand from MA to APDMS does not significantly affect the UV absorbance of the InP QDs, but quenches the PL to about 10% of its original value with the relative increase in surface related emission intensities, which is explained by stronger coordination of the APDMS ligands to the surface indium atoms. InP QD-organosilicon nanocomposites were synthesized by connecting the QDs using a short cross-linker such as 1,4-divinyltetramethylsilylethane (DVMSE) by the hydrosilylation reaction. The formation and changes in the optical properties of the InP QD-organosilicon nanocomposite were monitored by ultraviolet visible (UV-vis) absorbance and steady state photoluminescence (PL) spectroscopies. As the hydrosilylation reaction proceeds, the QD-organosilicon nanocomposite is formed and grows in size, causing an increase in the UV-vis absorbance due to the scattering effect. At the same time, the PL spectrum is red-shifted and, very interestingly, the PL is quenched gradually. Three PL quenching mechanisms are regarded as strong candidates for the PL quenching of the QD nanocomposites, namely the scattering effect, F$\ddot{o}$rster resonance energy transfer (FRET) and cross-linker tension preventing the QD's surface relaxation.

• 수산해양기술연구
• /
• 제44권4호
• /
• pp.265-272
• /
• 2008

Biodegradable polybutylene succinate(PBS) is an environment friendly plastics for fisheries, because it can mitigate the ghost fishing problem caused by gill-net and trap fisheries. To evaluate photodegradability of PBS monofilament in comparison with polyamide(PA) and polyethylene(PE) monofilament, these 3 types of monofilaments were spun and exposed to ultraviolet light(UV) of weather-ometer for 900 hours, and then their modification, crystal structure, strength, and extensibility were analysed. PBS monofilament did not show any crack and maintained its crystal structure after 900 hour exposure to UV whereas PE monofilament began showing cracks and structure modification after 600 hour exposure. Under UV exposure, the strength and extensibility decreased more rapidly in PBS than in PA and PE. We estimate that gill nets made of PBS monofilament can endure for about 1 year. The breaking strength and elongation decreased linearly with the exposure time for the 3 types of monofilaments. The derived regression equations of the residual tenacity(RT, kg/$mm^2$) and the residual extensibility(RE, %) with the exposure time in year(Y) for each monofilament were; PBS : RT=48.598 - 8.6437Y($R^2=0.93$), RE=28.165 - 7.3233Y($R^2=0.98$), P A : RT=59.771 - 8.6437Y($R^2=0.98$), RE=32.198 - 5.2772Y($R^2=0.92$), P E : RT=60.898 - 5.6528Y($R^2=0.98$), RE=11.887 - 0.7188Y($R^2=0.98$).

• 한국의류학회지
• /
• 제28권6호
• /
• pp.795-806
• /
• 2004

Unripe indigenous persimmons which contain rich tannins have been used as natural dye materials traditionally and have been using continuously for dyed clothes named Gal-ot in Jeju. Those persimmons were cheap and easy to use as dyes because of inedible and widely cultured in Korea. Persimmon juice dyes not only make fabrics brown-color but also give functional and hygienic properities such as stiffness, air ventilation of clothes, antibacterial activity, protectivity against ultraviolet light. However there are several serious problems which are ristriction of dyeing periods, longtime irradiation, uneven color and low color fastness etc. in persimmon juice dyeing. This study purpose to improve dye effect and method in order to enlarge useability of persimmon juice dyeing. Cotton fabrics were pad-dyed to 100% pick-up using padding machine after dipping in persimmon juice extracted from unripe persimmons indigenous from Jeju. It was possible and available to control pick-up rate. The color of dyed cotton fabrics by padding method was more even and repeatable than which by traditional hand method. Persimmon juice concentrations were 4 types of 10, 25, 50 and 100％. The more concentration increased, the more color deepened. UV Irradiation instead of sunlight was applied to color developing. Irradiation times were shortened till 1∼8 hrs. Same color values could be taken without water wetting which were required in sunlight irradiation. Tensile strengths of cotton fabrics pad-dyed with low concentration of persimmon juice decreased but recovered at high concentrations. Elongations(％) of cotton fabrics pad-dyed with persimmon juice were increased 1％ more than undyed cotton in sunlight irradiation. Drape stiffness increased upto double times as much as.

• 한국세라믹학회지
• /
• 제43권5호
• /
• pp.304-308
• /
• 2006

We have synthesized a $Eu^{2+}-activated\;Sr_3MgSi_2O_8$ blue phosphor and $(Sr,Ba)_2SiO_4$ yellow phosphor and prepared white LEDs by combining these phosphors with a InGaN UV LED chip. Three distinct emission bands from the InGaN-based LED and the two phosphors are clearly observed at 405 nm, 460 nm and at around 560 nm, respectively. The 405 nm emission band is due to a radiative recombination from a InGaN active layer. This blue emission was used as an optical transition of the $Sr_3MgSi_2O_8:Eu$ blue phosphor and $(Sr,Ba)_2SiO_4:Eu$ yellow phosphor. The 460 nm and 560 nm emission band is ascribed to a radiative recombination of $Eu^{2+}$ impurity ions in the $Sr_3MgSi_2O_8:Eu$ and $(Sr,Ba)_2SiO_4$ host matrix. As a consequence of a preparation of UV White LED lamp using the $Sr_3MgSi_2O_8:Eu$ blue phosphor and $(Sr,Ba)_2SiO_4:Eu$ yellow phosphor, the highest luminescence efficiency was obtained at the ration of epoxy/two phosphor (1/0.2361). At this time, the CIE chromaticity was CIE x = 0.3140, CIE y = 0.3201 and CCT (6500 K).

• 공업화학
• /
• 제33권1호
• /
• pp.50-57
• /
• 2022

본 연구에서는 RF/DC 마그네트론 증착법을 이용하여 유리 기판 상에 실온에서 TIZO/Ag/TIZO 다층막 투명전극 필름을 증착하였다. 전체 박막 두께 60 nm TIZO/Ag/TIZO (10 nm/10 nm/40 nm)로 이루어진 다층막의 경우 650 nm에서 투과도는 86.5%, 면저항 값은 8.1 Ω/□를 나타냈으며, 적외선(열선)을 효과적으로 차단할 수 있는 투과도 특성 때문에 향후 에너지 절약형 스마트 윈도우로서의 적용도 가능할 것으로 판단된다. TIZO/Ag/TIZO 다층막 투명전극을 적용한 폴리에스터 아크릴레이트 기반 고분자분산액정(polymer-dispersed liquid crystal, PDLC) 시스템에 있어서 액정과 prepolymer의 함량비, PDLC 코팅층의 두께 및 자외선 세기 변화에 따른 전기광학 특성 및 표면 형태학에 미치는 영향이 조사되었다. 15 ㎛의 PDLC 층 두께에 1.5 mW/cm²의 UV 세기로 광경화된 TIZO/Ag/TIZO 다층막 투명전극 적용 PDLC 셀이 전반적으로 양호한 구동 전압과 on-state 투과도 및 뛰어난 off haze를 나타냈으며, PDLC 복합체의 고분자 매트릭스 표면에 형성된 액정 droplet들은 입사광을 효율적으로 산란시킬 수 있는 1~3 ㎛ 크기를 갖고 있었다. 또한, 본 연구에서 제조된 TIZO/Ag/TIZO 다층막 투명전극 적용 PDLC 기반 스마트 윈도우는 연한 갈색의 색조를 띠고 있어서 심미적 측면에서 색다른 장점을 부여할 것으로 기대된다.

• 한국재료학회지
• /
• 제8권6호
• /
• pp.520-525
• /
• 1998

활성제로 $Eu^{+2}$을 사용한 BaO-MgO-$AI_2O_3$에서 화학조성 변화에 따른 청색 형광체의 광학특성을 254nm 자외선 및 147nm의 진공자외선 하에서 측정하였다. 동 형광체는 자외선 및 진공자외선 조사를 받아 주 파장이 445nm 인 가시광선의 청색을 발하는 형광체이다. $BaMgAI_{14}O_{23}$ : Eu 농도에 따라 증가하였으며 진공자외선의 경우에는 5%농도에서 최대가 됨을 알 수 있었다. 자외선 및 진공자외선 모두에서 $BaMgAI_{10}O_{17}$형광체의 청색 발광강도는$BaMgAI_{14}O_{23}$보다 좋았다. 또한 $BaMgAI_{10}O_{17}$에서 Ba대신 Ca이나 Sr을 0.1mole 치환시킨 $Ba_{0.9}Ca_{0.1}MgAI_{10}O_{17}$과 $Ba_{0.9}Sr_{0.1}MgAI_{10}O_{17}$ 형광체로 광특성을 더욱 개선할 수 있었다.