• 공업화학
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• 제16권3호
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• pp.449-455
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• 2005

분자 내에 방무기능을 부여하기 위한 수산기와 전자선(EB) 및 자외선(UV) 경화가 가능한 아크릴레이트 관능기를 갖는 1관능성 및 4관능성 방무제 AF-1과 AF-2를 합성하여 EB 및 UV 경화시스템에 적용하였다. 합성된 AF-1과 AF-2를 UV 경화시스템에 적용하여 도막의 방무특성 및 경화물성을 측정한 결과, AF-1과 AF-2 함량을 5:17.5의 비로 함유한 배합이 표면과 내부경도, 내화학성 및 접착력이 저하되지 않으면서 김서림 방지 특성이 우수한 최적배합임을 알 수 있었다. 이 최적배합을 EB 경화시스템에 적용하였고, EB 및 UV 두 시스템에 의해 이루어진 코팅배합물을 PC sheet에 코팅하여 도막의 방무특성 및 경화물성을 비교 연구하였다. 그 결과 EB 및 UV에 의해 경화된 두 시스템 모두 우수한 방무특성을 나타냈으나 EB 시스템이 UV 시스템보다 더우수한 내부경도, 접착력 및 젖음성을 나타냄을 확인하였다.

• 환경위생공학
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• 제14권4호
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• pp.143-149
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• 1999

In the tungsten industry as light source material, tungsten filament which used as light source material could form after molybdenumwire which used as the center supporter for coil shape tungsten wire was removed. This process uses hydrogen peroxide, Ozone and UV(Ultraviolet)Lamp, for the quantity of hydrogen peroxide decrease. The results were as follows : 1. An incandescent electric Lamp type : FL(FL-20) type : A standard of commodity (P.W.: $19{\pm}1.0mg$, $C.R:4.5{\pm}0.3{\Omega}$) 1) Only hydrogen peroxide treated ; Reaction Time : 65Min., P.W.: 18.60mg, $C.R.:4.60{\Omega}$ 2) Ozone/Ultraviolet/70% of hydrogen peroxide; Reaction Time : 64Min., P.W.: 18.61mg, C.R.: $4.61{\Omega}$ 2. A Fluorescent Lamp Type : GLS(GLS-40) Type : A standard of commodity(P.W.: $11.8{\pm}0.2mg$$65{\pm}1.5{\Omega}$) 1) Only hydrogen peroxide treated ; Reaction Time: 72Min, P.W.:11.88mg, C.R.: $65.62\Omega$ 2) Ozone/Ultraviolet/70% of hydrogen peroxide;Reaction Time:71Min., P.W.:11.88mg, C.R.: $65.63\Omega$

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 1998년도 공동 심포지엄 및 추계학술발표회
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• pp.206-215
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• 1998

Using of geosynthetics with linear materials(sand, gravel, clay soil) is rapidly increased in landfill. With geosynthetics, geotextiles often expose to solar radiation(Ultraviolet) on long terms during the installation. In this paper, the results will represent the strength retention rate and tensile retention rate of geotextiles between outdoor exposed and protected by 15cm thickness of soil. As a result of cumulating solar radiation in geotextiles was increased, the strength retentions rate of P.P(500g/$m^2$), P.P(700g/$m^2$) and P.P(1000g/$m^2$) were decreased and the lower weight of unit area of geotextiles, the faster decrease of strength retention rate. P.E.T(600g/$m^2$) was showed a distinctive trend that the strength retention rate increased. The tensile retention rate of tested geotextiles was decreased during the simulation. However, the strength and tensile retention rate of geotextiles covered by soil had changed insignificantly. Therefore, it can surmise that the soil covering will help geotextiles to be protected from UV effecting

• Journal of the Korean Physical Society
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• 제73권12호
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• pp.1879-1883
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• 2018

We analyzed the deep-trap states of GaN/InGaN ultraviolet light-emitting diodes (UV LEDs) before and after electrical stress. After electrical stress, the light output power dropped by 5.5%, and the forward leakage current was increased. The optical degradation mechanism could be explained based on the space-charge-limited conduction (SCLC) theory. Specifically, for the reference UV LED (before stress), two sets of deep-level states which were located 0.26 and 0.52 eV below the conduction band edge were present, one with a density of $2.41{\times}10^{16}$ and the other with a density of $3.91{\times}10^{16}cm^{-3}$. However, after maximum electrical stress, three sets of deep-level states, with respective densities of $1.82{\times}10^{16}$, $2.32{\times}10^{16}cm^{-3}$, $5.31{\times}10^{16}cm^{-3}$ were found to locate at 0.21, 0.24, and 0.50 eV below the conduction band. This finding shows that the SCLC theory is useful for understanding the degradation mechanism associated with defect generation in UV LEDs.

• Tribology and Lubricants
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• 제38권6호
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• pp.247-254
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• 2022

Chemical mechanical polishing (CMP) is a hybrid surface-polishing process that utilizes both mechanical and chemical energy. However, the recently emerging semiconductor substrate and thin film materials are challenging to process using the existing CMP. Therefore, previous researchers have conducted studies to increase the material removal rate (MRR) of CMP. Most materials studied to improve MRR have high hardness and chemical stability. Methods for enhancing the material removal efficiency of CMP include additional provision of electric, thermal, light, mechanical, and chemical energies. This study aims to introduce research trends on CMP using ultraviolet (UV) light to these methods to improve the material removal efficiency of CMP. This method, photocatalysis-assisted chemical mechanical polishing (PCMP), utilizes photocatalytic oxidation using UV light. In this study, the target materials of the PCMP application include SiC, GaN, GaAs, and Ru. This study explains the photocatalytic reaction, which is the basic principle of PCMP, and reviews studies on PCMP according to materials. Additionally, the researchers classified the PCMP system used in existing studies and presented the course for further investigation of PCMP. This study aims to aid in understanding PCMP and set the direction of future research. Lastly, since there have not been many studies on the tribology characteristics in PCMP, research on this is expected to be required.

• Journal of Ceramic Processing Research
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• 제21권
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• pp.23-27
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• 2020

The enhanced optical output power of AlGaN/GaN deep ultraviolet light-emitting diodes (UV LEDs) were demonstrated by using the breakdown-induced conductive channels (BICCs). The BICCs could be made by electrical reverse biasing between two adjacent contact pads formed on top p-type layers with a certain distance, causing an electrical breakdown of pn junction and hence a generation of conductive channels. Accordingly, the reflective Ni/Ag/Pt electrodes could be formed simultaneously on the top p-type layer and the other p-type layer with the BICCs, acting as the p- and n-contacts, respectively. The deep UV LEDs fabricated with the BICCs produced the enhanced optical output power by 15 % as compared to the reference LEDs, which were fabricated with the conventional Ti/Al/Ti/Au layers formed on mesa-etched n-type layer. This could be due to the reduced light absorption at the n-contact pads, indicating that the use of BICCs will be very suitable for obtaining better output performance of deep UV emitters.

• 대한화장품학회:학술대회논문집
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• 대한화장품학회 1992년도 자외선 차단 화장품의 SPF에 관한 심포지움(대한화장품학회)
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• pp.69-78
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• 1992

It is well hewn that ultraviolet light(UV) penetrates into the skin depends on the wavelength and causes many biochemical reactions in the skin. The enormous amount of information reveals that UV effects sun-burn, sun-tan and photoaging etc. In addition to these, it is now recognized that UV initiates immuno-suppression, and associated with this, skin cancer. In this review, I tried to illuminate the processes of injurious effects of UV on the skin.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.1115-1116
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• 2011

• 한국환경보건학회지
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• 제33권2호
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• pp.123-131
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• 2007

Many environmental contaminants including several metals, polycyclic aromatic hydrocarbons, and pharmaceuticals, have been identified to be phototoxic in the water environment. Concerns regarding photo-enhancement of toxicity of several environmental contaminants have been increasing because of the increased level of ultraviolet irradiation on the earth surface. However, there exist arguments that there might be certain defense mechanisms taking place in the aquatic ecosystem, which may include behavioral characteristics or genetic acclimation. This study was conducted to understand the potential responses of aquatic receptors to several phototoxic metals in the real environment, where long-term acclimation of such organisms to low dose UV-B may take place. For this purpose, water flea Daphnia magna was acclimated to environmentally relevant dose of UV-B (12 to $18uW/cm^2$) for >11 generations. The differences in developmental and life history characteristics, and toxicity responses were evaluated. Acclimation did not affect the daphnids' growth, longevity, and reproduction characteristics such as time to first brood, and brood size: After 21 d, survival of D. magna was not influenced by UV-B acclimation. When the number of young per female was compared. the daphnids acclimated for 11 generations tend to produce less number of neonates than the un-acclimated individuals but with no statistical significance (p>0.05). Four metals that were reported to be phototoxic elsewhere were employed in this evaluation, that include As, Cd. Cu, and Ni. UV-B level being applied in acclimation did increase the toxicity of Cd and Cu, significantly (p<0.05). However, the toxicities of As and Ni were not affected by irradiation of UV-B. Phototoxic responses were evaluated between the acclimated and the un-acclimated daphnids. For Cu, UV-B acclimation led to reduction of the photo-induced toxicity $(p\approx0.1)$ in daphnids. Non-acclimated Daphnia were affected by 50% at 4.18 ug/l Cu. but UV-B acclimated individuals exhibited $EC_{50}$ of 5.89 ug/l. With Cd, UV-B acclimation appeared to increase phototoxicity (p>0.05). With As and Ni, UV-B acclimation did not influence photo-induced toxicity. This observation may be in part explained by the type of reactive oxygen species that were generated by each metal. Similar to UV-B light, Cu is known to generate superoxide anion by acting as redox cycling toxicant. This is one of the first studies that employed_laboratory based UV-B acclimated test species for photoenhanced toxicity evaluation.

• 천문학회보
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• 제41권2호
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• pp.62.3-63
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• 2016

We studied the young stellar populations of star-forming (SF) regions in M33 based on the Galaxy Evolution Explorer (GALEX) ultraviolet (UV) imaging data. The SF regions are defined from far-UV data with various thresholds. We examined the reddening and spatial distribution of hot massive stars within SF regions from Hubble Space Telescope multi-band survey and Local Group Galaxy Survey (LGGS) data. The H-alpha sources from the LGGS are used for comparing with the spatial distribution of SF regions. The GALEX UV flux measurements of SF regions are used to derive their ages and masses. We also estimated the size and density of SF regions. The younger and compact SF regions are often arranged within older and sparser SF complexes. The results allow us to understand the hierarchical star formation and recent evolution of M33.