• 적정기술학회지
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• 제6권2호
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• pp.226-237
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• 2020

As the number of reported COVID-19 cases rises around the world, regions affected by the virus are taking serious measures to contain its spread. Face shields are one of the highest-need personal protective equipment (PPE) during COVID-19 pandemic. Beyond traditional face masks, as known cases of the coronavirus soar, currently there is a significant shortage of face shields around the world. In response, the protective face shields were designed and fabricated with open-source 3D modelling software and 3D printing technology, respectively. Our face shield consisted of two parts only; a reusable 3D printed headband and a visor made of transparent plastic sheet, as barrier. The resulting 3D printed face shields are affordable, lightweight, one-size-fits-most and ready-to-wear with minimal assemblies, and go on easily over glass, goggle and face mask. To ensure being donated to the healthcare professionals without risk infected by any pathogens, the 3D printed face shields were successfully be disinfected with ultraviolet germicidal irradiation (UVGI dosage of 1000 mJ/cm²) and 70% alcohol. For routine disinfection a UVGI chamber was designed and optimized to provide uniform UV-C illumination with an appreciated fluence for complete decontamination. More than 1,000 face shields were produced already and donated to the special hospitals for COVID-19 patients, quarantines, government and medical agencies in Ethiopia as well as in East-African countries. With certainty, our intention goes beyond the hospitals and other first responders, but not limited for all those who have to stay in the service or be in contact with many other people in the time of COVID-19 pandemic.

• Journal of Microbiology and Biotechnology
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• 제31권7호
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• pp.990-998
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• 2021

Melanin is a natural skin pigment produced by specialized cells called melanocytes via a multistage biochemical pathway known as melanogenesis, involving the oxidation and polymerization of tyrosine. Melanogenesis is initiated upon exposure to ultraviolet (UV) radiation, causing the skin to darken, which protects skin cells from UVB radiation damage. However, the abnormal accumulation of melanin may lead to the development of certain skin diseases, including skin cancer. In this study, the antioxidant and antimelanogenic activities of the cell-free supernatant (CFS) of twenty strains were evaluated. Based on the results of 60% 2,2-diphenyl-1-picrylhydrazyl scavenging activity, 21% 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) scavenging capacity, and a 50% ascorbic acid equivalent ferric reducing antioxidant power value, Limosilactobacillus fermentum JNU532 was selected as the strain with the highest antioxidant potential. No cytotoxicity was observed in cells treated with the CFS of L. fermentum JNU532. Tyrosinase activity was reduced by 16.7% in CFS-treated B16F10 cells (but not in the cell-free system), with >23.2% reduction in melanin content upon treatment with the L. fermentum JNU532-derived CFS. The inhibitory effect of the L. fermentum JNU532-derived CFS on B16F10 cell melanogenesis pathways was investigated using quantitative reverse transcription polymerase chain reaction and western blotting. The inhibitory effects of the L. fermentum JNU532-derived CFS were mediated by inhibiting the transcription of TYR, TRP-1, TRP-2, and MITF and the protein expression of TYR, TRP-1, TRP-2, and MITF. Therefore, L. fermentum JNU532 may be considered a potentially useful, natural depigmentation agent.

• 대한본초학회지
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• 제27권6호
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• pp.43-48
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• 2012

Objectives : This study was investigated to determine the contents of pesticide residues and sulfur dioxide residues in commercial herbal medicines in Korea. Methods : Chromatographic test was performed on 100 samples consisted with 10 kinds of medicinal plants including improted and domestic products. To establish 19 pesticide residues (DDE, DDD, DDT, Dieldrin, Methoxychlor, BHC isomers, Aldrin, Endosulfan isomers, Endrin, Captan, Procymidone, Chlorpyrifos and Imidacloprid) in commercial herbal medicines, chromatographic equipments were used with the gas chromatography-mass detector and gas chromatography-electron capture detector for qualitative analysis. The imidacloprid analysis was performed by high performance liquid chromatograpgy-ultraviolet detector at 270 nm UV wavelength. The contents of sulfur dioxides were analyzed by modified Monnier-Williams method. All methods were based on notification procedure of Korea Food & Drug Administration (KFDA). Results : The residual pesticides were not founded in improted and domestic samples. Among 100 samples, the residues of sulfur dioxide in 73 samples were not detected and 25 samples showed contents in the range of 0~21.90 mg/kg. The excess samples of MRLs were 2 samples (30 mg/kg to medicinal herbs), Asiasari Radix et Rhizoma (Imported product) and the average amount of sulfur dioxide in 2 unsuitable samples were 14.83 mg/kg. These samples were found to transgress KFDA regulatory guidance of residual sulfur dioxide. Conclusion : These results are able to use as basic data to improve the reliability and value of commercial medicinal herbs.

• Corrosion Science and Technology
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• 제21권6호
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• pp.434-444
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• 2022

Corrosion inhibitors based on Zn-Al hydrotalcites containing benzoate (ZnAlHB) with different molar ratios of Zn/Al were prepared with a co-precipitation process. Compositions and structures of the resulting hydrotalcites were studied with suitable spectroscopic methods such as inductively coupled plasma mass spectrometry (ICP-MS), ultraviolet-visible spectrophotometry (UV-Vis), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and surface zeta potential measurements, respectively. Results of physico-chemical studies showed that crystallite sizes, compositions of products, and surface electrical properties were significantly changed when the molar ratio of Zn/Al was increased. The release of benzoate from hydrotalcites also differed slightly among samples. Anticorrosion abilities of hydrotalcites intercalated with benzoate at a concentration of 3 g/L on carbon steel were analyzed using electrochemical impedance spectroscopy (EIS), polarization curve, energy-dispersive X-ray spectroscopy (EDX), and SEM. Corrosion inhibition abilities of benzoate modified hydrotalcites in 0.1 M NaCl showed an upward trend with increasing Zn/Al ratio. The reason for the dependence of corrosion resistance on the Zn/Al ratio was discussed, including changes in the microstructure of hydrotalcites such as crystal size, density, uniformity, and formation of ZnO.

• 대한의생명과학회지
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• 제28권3호
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• pp.186-191
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• 2022

The use of earphones has recently been widely used around the world. In currently, students wear earphones a lot in a daily life. The types of earphones are open-earphones, Canalphones, and headphones. Many students don't periodically to sterilization their earphones. Therefore, it can be an incubator that can induced ear infections. The objective of this study was to detect the pathogenic bacteria from the earphones used by the students. A total of 3 type earphones swabs were collected by sterile cotton swabs. The swabs were inoculated onto BHI agar and incubated aerobically 48 hour at 37℃. 16s rRNA PCR, electrophoresis and sequencing were performed to confirm the identification of all the bacterial isolates. As a result, 24 pathogens were identified in sequencing. Three types of earphones were sterilized in three ways: ultraviolet (UV), 70% ethyl alcohol, and antibacterial wet tissue. If you use earphones for a long time without disinfecting them for a long time, it causes various diseases such as external ear infections. The findings of this study the users periodically to sterilization their respective earphones.

• 청정기술
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• 제28권2호
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• pp.147-154
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• 2022

Titanate nanotubes (TNTs) were synthesized via alkaline hydrothermal treatment using commercial TiO₂ nanoparticles (P25). The TNTs were prepared at various TiO₂/NaOH ratios, hydrothermal temperatures, and hydrothermal times. The synthesized catalysts were characterized by X-ray diffraction, field-emission scanning electron microscopy, N₂ adsorption-desorption isotherms, field-emission transmission electron microscopy, and ultraviolet-visible spectroscopy. TNTs were generated upon a decrease in the TiO₂/NaOH ratio due to the dissolution of TiO₂ in the alkaline solution and the generation of new Ti-O-Ti bonds to form titanate nanoplates and nanotubes. The hydrothermal treatment temperature and time were important factors for promoting the nucleation and growth of TNTs. The TNT catalyst with the largest surface area (389.32 m² g^-1) was obtained with a TiO₂/NaOH ratio of 0.25, a hydrothermal treatment temperature of 130 ℃, and a hydrothermal treatment time of 36 h. Additionally, we investigated the photocatalytic activity of methyl violet 2B (MV) over the TNT catalysts under UV irradiation and found that the degradation efficiencies of the TNTs were higher than that of P25. Among the TNT catalysts, the TNT catalyst that was hydrothermally synthesized for 36 h (TNT 36 h) exhibited a 96.9% degradation efficiency and a degradation rate constant that was 4.8 times higher than P25 due to its large surface area, which allowed for more contact between the MV molecules and TNT surfaces and facilitated rapid electron transfer. Finally, these results were correlated with the specific surface area.

• 생약학회지
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• 제53권2호
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• pp.111-118
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• 2022

Chestnut honey is a sweet dark-colored honey with a distinct bitter aftertaste. It contains numerous phenolic compounds and alkaloids and is noted for its antioxidant and anti-inflammatory activities. However, it has been established that there are differences in the composition and activity of chestnut honey constituents depending on the region of origin, the sources of which warrant further research. In this study, we analyzed the kynurenic acid (KA) contents in chestnut honey produced in nine different regions in Korea, using high-performance liquid chromatography in conjunction with ultraviolet detection, and validated the analytical method developed. Use of a reverse-phase column and detection at a wavelength of 240 nm were found to be optimal for the detection of KA. Similar evaluation of an optimal method for extracting KA from chestnut honey revealed that extraction using 10% EtOH at 20 times the sample volume over a 6 h period was the most suitable for obtaining a high content of KA. Among the nine regional chestnut honeys assessed, KA content was found to be highest in the "Gongju" sample (1.14 mg/g), followed by that in the "Cheongdo" and "Damyang" samples. Validation of the KA analytical method revealed a good analyte linearity, with a correlation coefficient (r²) of 0.9995, an accuracy of between 92.37% and 107.35%, and good precision (RSD ≤ 1.05%). Our findings in this study, based on a validated quantitative analytical method for KA, could make an important contribution to establishing a data profiling procedure for characterizing chestnut honeys produced in different regions, and may also provide basic data for the identification of functional honey.

• 토지주택연구
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• 제13권2호
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• pp.117-123
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• 2022

본 연구는 대표적인 미세먼지와 실내유해물질인 질소산화물의 저감을 위해 이산화티탄 광촉매를 환기장치에 적용한 것으로 그 내용은 다음과 같다. 기존 연구는 실내에 자외선 적용의 한계로 인해 주로 건축자재에 광촉매 혼입을 통해 실외 자재를 대상으로 진행되었다. 자외선 실내 적용 한계를 극복하고자 기존 선행연구를 통해 확인된 이산화티탄 광촉매의 오염물질 분해 효과를 실내에 적용이 가능하도록 자외선램프의 설치가 가능한 반응장치를 설계 및 제작하였다. 해당 반응장치를 실내 환기장치에 적용하여 Mock-Up에 적용하였다. Mock-Up 실험은 그 체적을 시간당 1회, 5회 환기하는 풍량을 변화시켜 NOx 저감 성능을 확인하였다. 그 결과, 환기 풍량이 증가함에 따라 NOx 저감시간이 비례하여 감소되어 그 성능이 증가하는 것을 확인하였다. 해당 연구를 통해 오염물질 저감 효과를 가진 이산화티탄 광촉매의 실내 활용 방안과 그 성능을 확인할 수 있는 기초적인 연구 결과를 도출하였다.

• 한국표면공학회지
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• 제56권3호
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• pp.208-218
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• 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.

• 분석과학
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• 제22권1호
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• pp.65-74
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• 2009

옻나무는 아시아지역 전역에 주로 분포하며 예로부터 도료 및 약용 식물로 많이 사용되어져 왔었다. 특히 우리나라에서 재배되는 옻나무가 그 기능이 더욱 우수하다고 알려져 있는데 그 원인은 명확히 밝혀진 바가 없다. 우선 옻나무에서 우루시올의 추출을 위하여 나무는 soxhlet의 방법으로, 옻나무 추출물은 liquid-liquid extraction (LLE)의 방법을 이용하여 각각의 우루시올을 추출하였으며, 추출한 각 성분들은 high performance liquid chromatography/ultraviolet & visible detector system (HPLC/UV-Vis)에 먼저 적용하여 분리의 최적 조건을 찾았다. 그리고 각 성분에 대한 정확한 분석을 위하여 reverse phase liquid chromatography on-line electro spray ionization mass spectrometer (LC-MS/MS)를 이용하였으며 이를 바탕으로 분자량에 따른 성분 확인과 함량을 연구하였다. 이동상의 조건으로는 methanol : 0.1% formic acid : DDW를 929 : 1 : 70의 부피비로 사용하여 최적의 분리 조건을 얻었다. 이러한 LC의 조건으로 다시 LC-MS/MS에 적용하여 MRM의 방식으로 각각의 함량을 구할 수 있었다. 분자량에 따라 총 4종류의 우루시올 동종체들이 존재를 확인하였다. 본 연구를 통하여 한국산 옻나무 추출물의 경우 외국산 옻나무의 것 보다 곁사슬에 이중결합이 많은 우루시올 동종체의 함량이 많이 존재하며 그 전체적 비율이 높은 것으로 밝혀졌다.