• Journal of Powder Materials
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• v.28 no.1
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• pp.25-30
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• 2021

The surface of silicon dummy wafers is contaminated with metallic impurities owing to the reaction with and adhesion of chemicals during the oxidation process. These metallic impurities negatively affect the device performance, reliability, and yield. To solve this problem, a wafer-cleaning process that removes metallic impurities is essential. RCA (Radio Corporation of America) cleaning is commonly used, but there are problems such as increased surface roughness and formation of metal hydroxides. Herein, we attempt to use a chelating agent (EDTA) to reduce the surface roughness, improve the stability of cleaning solutions, and prevent the re-adsorption of impurities. The bonding between the cleaning solution and metal powder is analyzed by referring to the Pourbaix diagram. The changes in the ionic conductivity, H2O2 decomposition behavior, and degree of dissolution are checked with a conductivity meter, and the changes in the absorbance and particle size before and after the reaction are confirmed by ultraviolet-visible spectroscopy (UV-vis) and dynamic light scattering (DLS) analyses. Thus, the addition of a chelating agent prevents the decomposition of H2O2 and improves the life of the silicon wafer cleaning solution, allowing it to react smoothly with metallic impurities.

• Textile Coloration and Finishing
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• v.35 no.2
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• pp.67-81
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• 2023

This study aims to examine the possibility of using dried Dondropanax morbiferus extract as a functional dye. The leaves and branches of were extracted with distilled water and 30% ethanol, and the dyeability and functionality of silk fabrics were examined according to the color characteristics of the extract and dyeing conditions. As a result of analyzing the ultraviolet and visible light absorption spectrum of the extract, it was possible to confirm the peak of flavonoid belonging to polyphenol, and the peak of riboflavin expressing yellow color was confirmed. Adsorption equilibrium was observed at 4% dyeing concentration and 60 minutes of dyeing time, and as the temperature increased, dyeing amount increased without color change of Y-series. Aluminum mordanting also increased the yellow color. The color fastness of washing and UV irradiation was low, but the color fastness of rubbing was evaluated as relatively good. The silk fabric dyed with the distilled water extract of the leaves showed a 99.9% bacteriostatic reduction against Staphylococcus aureus and Klebsiella pneumoniae, showing excellent antibacterial properties.

• The Korean Journal of Community Living Science
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• v.18 no.1
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• pp.55-62
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• 2007

The purpose of this study was to determine the usefulness of Shiitake mushroom, which was rich in vitamin $D_2$ through UV irradiation. For the practical use, we prepared the cold buckwheat noodles using UV irradiated Shiitake mushroom powder and seaweed derived calcium. The time required to acquire $2.5 J/cm^2$ of UV was 30-45 minutes, when the mushrooms were disposed 18 cm below within 1 cm from the UV light. Among the texture profiles detected by texture analyzer, adhesiveness and chewiness were significantly influenced by addition of mushroom powder and/or calcium. Adhesiveness appeared in only 3% mushroom powder noodle, and chewiness was significantly decreased by both of mushroom powder and seaweed calcium. Shiitake powder lowered lightness(L) and yellowness(b), but these deminishing effect on L and B value were compensated with addition of seaweed clacium. With cooking, the value of L was increased and redness(a) and yellowness(b) were decreased in comparison with raw noodle. According to sensory evaluation, addition of Shiitake and calcium increased the preference scores of color and overall acceptance of cold buckwheat noodles, but flavor, taste and texture were not influenced by those ingredients. We concluded that addition of 5% Shiitake and/or calcium to cold buckwheat noodles might give advantages for born health without bad effects on characteristics of those noodles.

• Applied Chemistry for Engineering
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• v.28 no.6
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• pp.705-713
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• 2017

A novel material, $Bi_2WO_6-GO-TiO_2$ composite, was successfully synthesized using a facile hydrothermal method. During the hydrothermal reaction, the loading of $Bi_2WO_6$ and $TiO_2$ nanoparticles onto graphene sheets was achieved. The obtained $Bi_2WO_{6-GO-TiO2}$ composite photo-catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM), Raman spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy (UV-vis-DRS), and X-ray photoelectron spectroscopy (XPS). The $Bi_2WO_6$ nanoparticle showed an irregular dark-square block nanoplate shape, while $TiO_2$ nanoparticles covered the surface of the graphene sheets with a quantum dot size. The degradation of rhodamine B (RhB), methylene blue trihydrate (MB), and reactive black B (RBB) dyes in an aqueous solution with different initial amount of catalysts was observed by UV spectrophotometry after measuring the decrease in the concentration. As a result, the $Bi_2WO_6-GO-TiO_2$ composite showed good decolorization activity with MB solution under visible light. The $Bi_2WO_6-GO-TiO_2$ composite is expected to become a new potential material for decolorization activity. Photocatalytic reactions with different photocatalysts were explained by the Langmuir-Hinshelwood model and a band theory.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.87-87
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• 2010

Photoelectrochemical (PEC) systems are promising methods of producing H2 gas using solar energy in an aqueous solution. The photoelectrochemical properties of numerous metal oxides have been studied. Among them, the PEC systems based on TiO2 have been extensively studied. However, the drawback of a PEC system with TiO2 is that only ultraviolet (UV) light can be absorbed because of its large band gap (3.2 - 3.4 eV). Two approaches have been introduced in order to use PEC cells in the visible light region. The first method includes doping impurities, such as nitrogen, into TiO2, and this technique has been extensively studied in an attempt to narrow the band gap. In comparison, research on the second method, which includes visible light water splitting in molecular photosystems, has been slow. Mallouk et al. recently developed electrochemical water-splitting cells using the Ru(II) complex as the visible light photosensitizer. the dye-sensitized PEC cell consisted of a dye-sensitized TiO2 layer, a Pt counter electrode, and an aqueous solution between them. Under a visible light (< 3 eV) illumination, only the dye molecule absorbed the light and became excited because TiO2 had the wide band gap. The light absorption of the dye was followed by the transfer of an electron from the excited state (S*) of the dye to the conduction band (CB) of TiO2 and its subsequent transfer to the transparent conducting oxide (TCO). The electrons moved through the wire to the Pt, where the water reduction (or H2 evolution) occurred. The oxidized dye molecules caused the water oxidation because their HOMO level was below the H2O/O2 level. Organic dyes have been developed as metal-free alternatives to the Ru(II) complexes because of their tunable optical and electronic properties and low-cost manufacturing. Recently, organic dye molecules containing multi-branched, multi-anchoring groups have received a great deal of interest. In this work, tri-branched tri-anchoring organic dyes (Dye 2) were designed and applied to visible light water-splitting cells based on dye-sensitized TiO2 electrodes. Dye 2 had a molecular structure containing one donor (D) and three acceptor (A) groups, and each ended with an anchoring functionality. In comparison, mono-anchoring dyes (Dye 1) were also synthesized. The PEC response of the Dye 2-sensitized TiO2 film was much better than the Dye 1-sensitized or unsensitized TiO2 films.

• Journal of Society of Preventive Korean Medicine
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• v.19 no.1
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• pp.109-116
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• 2015

Objective : Solar ultraviolet (UV) light can cause photoaging of human skin. Many researchers have focused on effective prevention to mitigate the aging process. This study was aimed to investigate anti-wrinkle effects of pomegranate concentration solution (PCS) using photoaged hairless mouse model. Method : To clarify the protective effect of PCS against UVB-induced photo-damage, water capacity was measured with transepidermal water loss (TEWL) in SKH-1 hairless mice. In addition, image of skin replicas was analyzed. Results : Our results showed that the PCS treatment protects skin against UVB-induced photoaging, based on the parameters including moisture capacity and TEWL. According to visual assessment of skin replica, application of 1 ml/kg PCS inhibited UV-induced wrinkle formation in mice skin as compared to the vehicle-applied control mice. Conclusion : Taken together, these results indicated that PCS could improve skin wrinkle formation induced by UVB irradiation in SHK-1 hairless mice. PCS could be applied as an anti-wrinkle agent.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.31 no.5
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• pp.228-232
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• 2021

Ca_1-xZrO₃:xPr phosphor with perovskite structure was successfully synthesized by using skull melting method. The crystal structure, morphology and optical properties of synthesized phosphor were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet fluorescence reaction and photoluminescence. The XRD results indicated that single crystals of CaZrO₃:Pr³⁺ belongs to orthorhombic perovskite system. The synthesized phosphor could be excited by UV light (254 nm) and the emission spectra results indicated that green luminescence of CaZrO₃:Pr³⁺ due to charge transfer transition ³P₀ → ³H₄, ³P₁ → ³H₅ and ³P₀ → ³H₅ at 506, 536 and 548 nm was dominant.

• Food Engineering Progress
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• v.15 no.3
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• pp.257-261
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• 2011

Biodegradable plastics were developed using biodegradable pellets made of corn stalk and rice husk and their safety as food packages and their biodegradability against light (ultraviolet (UV)), heat, and fungi were evaluated. Four kinds of 50-${\mu}m$ biodegradable plastics were produced by extruding the mixtures of the biodegradable pellets, low-density polyethylene (LDPE), high-density polyethylene (HDPE), and linear low-density polyethylene (LLDPE) with different compositions. Developed biodegradable plastics were safe to be used as food packages. The initial tensile strength and percentage elongation of the plastics were similar to those of LDPE, but the values decreased with increased their exposure time to UV and heat. The fungal biodegradability of the biodegradable plastics was higher than that of LDPE. The biodegradability of the biodegradable plastics shows the potential for them to be used as sustainable food packages.

• Journal of the Korean Society for Marine Environment & Energy
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• v.18 no.4
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• pp.304-309
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• 2015

To evaluate the degree of contamination caused by oil spill accident in the sea, the in-situ sensors which are based on the scientific method are needed in the real site. The sensors which are based on the fluorescence detection theory can provide the useful data, such as the concentration of oil. However these kinds of sensors commonly are composed of the ultraviolet (UV) light source such as UV mercury lamp, the multiple excitation/emission filters and the optical sensor which is mainly photomultiplier tube (PMT) type. Therefore, the size of the total sensing platform is large not suitable to be handled in the oil spill field and also the total price of it is extremely expensive. To overcome these drawbacks, we designed the fluorimeter for the oil spill detection which has compact size and cost effectiveness. Before the detail design process, we conducted the experiments to measure the excitation and emission spectrum of oils using five different kinds of crude oils and three different kinds of processed oils. And the fluorescence spectrometer were used to analyze the excitation and emission spectrum of oil samples. We have compared the spectrum results and drawn the each common spectrum regions of excitation and emission. In the experiments, we can see that the average gap between maximum excitation and emission peak wavelengths is near 50 nm for the every case. In the experiment which were fixed by the excitation wavelength of 365 nm and 405 nm, we can find out that the intensity of emission was weaker than that of 280 nm and 325 nm. So, if the light sources having the wavelength of 365 nm or 405 nm are used in the design process of fluorimeter, the optical sensor needs to have the sensitivity which can cover the weak light intensity. Through the results which were derived by the experiment, we can define the important factors which can be useful to select the effective wavelengths of light source, photo detector and filters.

• Journal of Nutrition and Health
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• v.42 no.6
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• pp.516-522
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• 2009

In this study, the effects of a mixture consisting of vitamin E, vitamin C, pycnogenol and evening primrose oil (mixture LGNC-5) on ultraviolet light (UV) induced pigmentation and wrinkle reductions of normal healthy volunteers were studied. In a double-blind placebo-controlled study, each of 54 subjects took daily either 4 capsules of the mixture LGNC-5 (Group ABC; 282.5 mg/capsule) or placebo (Group Ganada). We irradiated 2.5 MED UV on the upper arms and measured the whitening effect by colorimeter-based L value. The level of wrinkle reduction was determined by image analysis using skin replica around the crow' feet, and the level of serum vitamin E was determined at baseline and 12 weeks. After 12-week oral administration, the treated group showed a significant reduction in skin pigmentation and wrinkles compared with the placebo group (p = 0.011 and p = 0.000005, respectively). Also, the level of serum vitamin E was significantly increased in the treated group after 12-week oral adminstration of the mixture compared with that in the placebo group (p = 0.0001). In conclusion, 12-week oral administration of LGNC-5 as a dietary supplement could be effective to reduce both UV induced pigmentation and skin wrinkle without side effects.