• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.3
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• pp.183-198
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• 2021

The EPB (Earth Pressure Balanced) shield TBM method restrains the ground deformation through continuous excavation and support. Still, the significant surface settlement occurs due to the ground conditions, tunnel dimensions, and construction conditions. Therefore, it is necessary to clarify the settlement behavior with its influence factors and evaluate the possible settlement during construction. In this study, the analytical model of surface settlement based on the influence factors and their mechanisms were proposed. Then, the parametric study for controllable factors during excavation was conducted by numerical method. Through the numerical analysis, the settlement behavior according to the construction conditions was quantitatively derived. Then, the qualitative trend according to the ground conditions was visualized by coupling the numerical results with the analytical model of settlement. Based on the results of this study, it is expected to contribute to the derivation of the settlement prediction algorithm for EPB shield TBM excavation.

• Korean Journal of Food Science and Technology
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• v.54 no.2
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• pp.115-125
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• 2022

Flavonoids are bioactive plant metabolites that have a range of beneficial effects on human health. Quercetin 4'-glycoside (Q4'G), quercetin 3,4'-diglycoside (Q3,4'G), and quercetin aglycone (QA) are the main flavonoids found in onions. QA, in particular, is likely to have a greater biological effect than glycosides. To develop an onion extract with high quercetin content, the optimal extraction conditions for red onion powder containing the outer layer of the onion were determined. The effects of acid treatment on the concentration of quercetin glycosides and QA were evaluated. The flavonoids of red onion powder were optimally extracted under 60-70% ethanol at 70℃ for 2 h. The deglycosylation of Q3,4'G and an increase in Q4'G content occurred within 6 h of 0.2% acetic acid treatment. The QA content and deglycosylation of Q4'G eventually peaked at 24 h. In addition, QA content and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity were highly correlated, with a correlation coefficient of 0.90.

• Journal of Korean Tunnelling and Underground Space Association
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• v.12 no.1
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• pp.75-85
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• 2010

The focus of this study is to evaluate the field applicability of the newly developed inorganic thixotropic-grout in various ways. In order to do this, the volume stability and the permeability of the inorganic thixotropic-grout have been measured and compared to the existing silica type grouts. In addition, the filling capability of the grout into the tail void has been evaluated through both an experiment with a miniature tail-void filling equipment and a test filling at the shield TBM construction site. The volume loss of the inorganic thixotropic-grout after a 14 day-curing under the atmosphere condition was appeared to be minimal. The excellent waterproofing ability of the inorganic thixotropic-grout was confirmed through a permeability test. The toxicity of the inorganic thixotropic-grout has been evaluated through a toxicity test of aquatic fishes (KS M 0111) and the pH value of the liquid eluviated from inorganic thixotropic-grout was measured as an average of 8.0 and a fatality rate of goldfish after 96 hours was 10% or so. The existence of harmful heavy metals in the liquid eluviated from the inorganic thixotropic-grout has been also examined through an atomic absorption spectroscopy (AAS) test. Any of harmful heavy metals were not detected and the detected level of $Cr^{6+}$ and Cd was far below the standard. Based on both an experiment with a miniature tail-void filling equipment and a test filling at the shield TBM construction site, the filling ability of inorganic thixotropic-grout into the tail void was proved to be excellent.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2022.09a
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• pp.25-25
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• 2022

피부 노화는 피부와 피부 지지층 등의 광범위한 퇴행 과정을 말한다. 피부 노화의 원인은 흡연, 공해, 스트레스 등이 있지만, 그 중에서도 자외선(ultra violet, UV) 조사가 가장 큰 요인으로 꼽힌다. 반복적인 자외선 조사에 의해 진행되는 피부노화를 광노화라고 하며 그 가장 큰 특징으로는 콜라겐 섬유와 엘라스틴의 감소로 야기되는 주름을 들 수 있다. 본 연구에서는 제주에서 채집한 바위수국의 추출물 및 분획물의 항산화 및 자외선으로 인한 피부노화 예방(anti-photoaging) 효능을 확인하고, 활성물질을 분리하여 광노화 예방 효능과 그 메커니즘을 확인하였다. 실험에 사용된 바위수국은 범의귀과의 덩굴성 식물로 바위면이나 나무줄기 등에 붙어서 자라며, 한국(제주, 울릉도)과 일본에 분포한다. 바위수국 추출물과 분획물에서 총 페놀 함량. 총 플라보이드 함량, DPPH 및 ABTS 라디칼소거 활성의 항산화 실험 결과, 부탄올과 에틸아세테이트 분획층에서 강력한 항산화 활성이 관찰되었다. 또한 UVA를 조사한 인간 진피 섬유아세포 (human dermal fibroblast, HDF)데 대한 콜라겐 분해효소인 matrix metalloproteinase-1(MMP-1) 생성 억제 활성을 확인한 결과, 부탄올 분획층이 세포 생장 저해 없이 가장 우수한 효능이 확인되었다. 따라서 부탄올 분획층에서 주요 성분 분리 실험을 수행하여 총 4개의 화합물을 분리하였다; Chlorogenic acid (1), Quercetin-3-O-glucosyl-(1-2)-rhamnoside (2), Quercetin-3-O-xylosyl-(1-2)-rhamnoside (3), Quercitrin (4). 분리한 4개의 물질의 MMP-1 생성 억제 활성을 비교한 결과 화합물 2가 세포독성 없이 MMP-1 생성 억제 효능이 우수하였고, 이후 화합물 2의 광노화 예방 효능과 그 메커니즘을 확인하였다. 화합물 2는 MMP-1의 생성을 억제할 뿐만 아니라 procollagen type I의 생성을 증가시켰으며, MMP-1 생성에 관여하는 mitogen-activated protein kinase (MAPK)/activator protein-1 (AP-1) 신호전달경로를 하향 조절하며, 콜라겐 생성과 관련된 Transforming growth factor-β (TGF-β)/Smad 신호전달경로를 상향 조절하여 UVA에 의한 광노화 예방에 효능을 나타내었다. 이러한 결과들을 바탕으로, 바위수국은 항노화(anti-aging) 기능성 화장품 및 이너뷰티 기능성 식품 소재로 개발이 가능할 것으로 기대된다.

• Food Science and Preservation
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• v.30 no.2
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• pp.300-310
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• 2023

This study was carried out to investigate the effect of the extraction conditions for persimmon (Diospyros kaki Thunb.) leaf tea (PLT) on its color quality and antioxidant properties. The amount of persimmon leaf (PL) powder and pH influenced the PLT's color and antioxidant capacity. As the amount of PL powder in tea increased, lightness decreased while yellowness increased. The PLT with the highest amount of PL (10 mg/mL) exhibited the highest 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging activity and ferric reducing antioxidant power (FRAP). In addition, the PLT with the highest PL showed the highest total polyphenol and flavonoid contents. Subsequently, PLT was prepared using 10 mg/mL PL powder under varying pH conditions. As pH increased from 4 to 7, lightness decreased while redness and yellowness increased. Antioxidant capacity was determined using 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity and FRAP assay showed that lower pH exhibited higher antioxidant capacity. The PLT extracted under the lowest pH of 4 showed higher polyphenol and flavonoid contents than that extracted under higher pH conditions. Overall, PLT extraction using a solvent with pH 4.0 showed better antioxidant activities and higher amounts of polyphenolic compounds. Simultaneously, lesser lightness, redness, and yellowness were detected in PLT extracted under pH 4 conditions. In conclusion, to acquire a better functional health benefit in terms of antioxidant capacity, preparing PLT under pH 4 conditions is suggested.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.1
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• pp.68-75
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• 2016

This study was conducted to provide information regarding changes in antioxidant activity in response to conching temperatures, conching times, and cacao mass content (CMC) in dark chocolate. The radical scavenging activities and functional components of cacao nibs were highest for raw cacao nib (R0) under all conditions. Moreover, antioxidant activities and functional compounds increased during roasting for 25 min. As the conching temperature increased, the radical scavenging activities and functional components increased. Quantitative analysis of major catechin-derived compounds by HPLC revealed that R0 had the highest value for other roasted cacao nibs in all aspects (P<0.05). The content of procyanidin B2, catechin, and epicatechin increased during roasting for 25 min. Finally, evaluation of couvertures revealed that procyanidin B1 content increased as conching time increased to 48 h, except for 70% CMC and conched at $60^{\circ}C$ (HH) and 70% CMC and conched at $50^{\circ}C$. Overall, HH48 contained the richest catechin-derived components.

• Journal of the Microelectronics and Packaging Society
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• v.12 no.4 s.37
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• pp.307-313
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• 2005

Electromigration behavior in the Sn96.5Ag3.0Cu0.5 solder lines was investigated and compared Sn96.5Ag3.0Cu0.5 with eutectic SnPb. Measurements were made for relevant parameters for electromigration of the solder, such as drift velocity, threshold current density, activation energy, as well as the product of diffusivity and effective charge number (DZ$\ast$). The threshold current density were measured to be $2.38{\times}10^4A/cm^2$ at $140^{\circ}C$ and the value represented the maximum current density which the SnAgCu solder can carry without electromigration damage at the stressing temperatures. The electromigration energy was measured to 0.56 eV in the temperature range of $110-160^{\circ}C$. The measured products of diffusivity and the effective charge number, DZ$\ast$ were $3.12{\times}10^{-10} cm^2/s$ at $110^{\circ}C$, $4.66{\times}10^{-10} cm^2/s$ at $125^{\circ}C$, $8.76{\times}10^{-10} cm^2/s$ at $140^{\circ}C$, $2.14{\times}10^{-9}cm^2/s$ at $160^{\circ}C$ SnPb solder existed incubation stage, while SnAgCu did not have incubation stage. It was thought that the diffusion mechanism of SnAgCu was different from that of SnPb.

• Journal of Life Science
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• v.19 no.11
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• pp.1598-1604
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• 2009

In order to determine chemical components of onion flesh and peel, general nutrients, vitamin C, and total flavonoids were measured. Onion peel showed less moisture (14.3%) and no vitamin C compared to onion flesh. Onion peel contained more amounts of total flavonoids compared to onion flesh. In addition, the inhibitory effects of solvent extracts from onion flesh and peel on $H_2O_$-induced oxidative stress and growth of cancer cell lines (AGS human gastric adenocarcinoma and HT-29 human colon cancer cells) were investigated. Acetone with methylene chloride (A+M) and methanol (MeOH) extracts from onion flesh and peel appeared to significantly reduce the levels of intracellular reactive oxygen species (ROS) (p<0.05) and a greater antioxidant effect was observed in onion peel. Among fractions, 85% aq. methanol showed a higher protective activity against oxidative stress in both flesh and peel and there was no effect in the water and hexane fractions. The growth of cancer cells exposed to medium containing extracts and fractions from onion flesh and peel was inhibited dose-dependently. The growth of AGS was inhibited more in both flesh and peel compared to HT-29, and onion peel was more effective than onion flesh. Among fractions, 85% aq. methanol showed the greatest effect on growth inhibition in both flesh and peel. $IC_{50}$ values of 85% aq. methanol fraction from onion flesh and peel on AGS were 0.04 and 0.03 mg/ml, respectively, while those on HT-29 were 0.23 and 0.04 mg/ml. From our results, 85% aq. methanol fraction had an inhibitory effect against oxidative stress and growth of cancer cells, suggesting that it may contain biological active compounds.