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정경한,김태훈 한국식품영양과학회 2019 한국식품영양과학회지 Vol.48 No.8
In this current study, we evaluated the enhancement of the antioxidant capacity and the degradation of trans-resveratrol as mediated by a dielectric barrier discharge plasma. The structures of the degradation products 1 and 2 from the trans-resveratrol treated with the plasma for 60 min were identified as being 3,5-dihydroxybenzaldehyde (1) and p-hydroxybenzaldehyde (2) by performing LC-MS analysis with using authentic samples. The antioxidant activity of plasma treated red wine was evaluated and the resulting two degradation products from red wine, 3,5-dihydroxybenzaldehyde (1) and p-hydroxybenzaldehyde (2) were also identified using LC-MS. The antioxidant property of the newly generated compounds from plasma treated red wine was measured based on 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS+) and hydroxyl radical scavenging assays. The ABTS+ and hydroxyl radical scavenging activity of red wine was increased from 46.5±2.6 to 59.0±4.1 μM ascorbic acid eq. and from 38.1±2.2 to 53.2±2.9 μM ascorbic acid eq., respectively, after 60 min of plasma treatment. The generated products, 1 and 2 exhibited improved radical scavenging activity as compared to the radical scavenging activity of the trans-resveratrol. trans-Resveratrol이 다량 함유된 적포도주를 대기압 플라즈마 처리 시 신규 생성 화합물을 LC-MS를 활용하여 분석하였다. 그 결과 화합물 1은 3,5-dihydroxybenzaldehyde, 화합물 2는 p-hydroxybenzaldehyde로 구조 동정하였으며, 플라즈마 처리를 통하여 순수한 trans-resveratrol로부터 화합물 1과 2가 생성되는 것을 확인하였다. 또한 플라즈마 처리시간이 증가할수록 trans-resveratrol은 감소하였으며, 플라즈마 미처리된 적포도주에서 검출되지 않았던 화합물 1 및 2는 플라즈마 처리물(60 min)에서 각각 12.4± 0.7, 23.5±1.0 mg/g의 함량으로 trans-resveratrol이 분해되고 함량이 증가한 것을 확인하였으며, 적포도주 플라즈마 처리물(60 min)이 ABTS+ 및 hydroxyl 라디칼 소거능 평가에서 각각 59.0±4.1 및 53.2±2.9 μM ascorbic acid eq.로 플라즈마 미처리된 적포도주에 비해 라디칼 소거능이 상승한 것을 확인하였다. 적포도주의 주성분인 trans-resveratrol 및 신규생성 화합물 1, 2의 라디칼 소거능을 평가한 결과, 신규 생성 3,5-dihydroxybenzaldehyde(1)는 각각 182.0±6.8 및 157.6±5.7 μM ascorbic acid eq.로 매우 우수한 ABTS+ 및 hydroxyl 라디칼 소거활성을 나타내었다. 또한 p-hydroxybenzaldehyde(2)는 각각 136.6±6.0 및 98.0±4.4 μM ascorbic acid eq.로 trans-resveratrol에 비하여 우수한 라디칼 소거활성을 확인하였다. 이상의 결과로부터 플라즈마 처리 시 적포도주의 주성분인 trans-resveratrol 유래의 저분자 페놀성 화합물이 생성되며, 이들 화합물이 포함된 플라즈마 처리 적포도주의 우수한 라디칼 소거활성에 관여함을 확인하였다. 향후 플라즈마 처리 시 식품의 주요 성분들의 구조변화 양상과 활성 상승과 관련하여 다양한 조건에서의 체계적인 연구가 필요하다고 사료된다.
정경한,신훈규,권영수 한국전기전자재료학회 2003 전기전자재료학회논문지 Vol.16 No.9
In recent years, there has been large interest in the fabrication of the self organized nanoscale structures since not only their potential utilization in electronic, optoelectronic, and magnetic devices but also their fundamental interest such as uniformity and regularization. An attractive candidate of these materials is anodic porous alumina film(Al$_2$O$_3$) which is formed by the anodization of aluminum in an appropriate acid solution. In this study to fabricate the porous alumina film with very uniform and nearly parallel pores the anodization was carried out under constant voltage mode in 0.3M oxalic acid as an electrolyte. The hexagonally ordered arrays with a few $\mu\textrm{m}$ in size two-dimensional polycrystalline structure were obtained of which pore densities were 1.1${\times}$10$\^$10//$\textrm{cm}^2$.
가압 그라우팅 쏘일네일링의 인발저항력 증가 원인에 관한 연구
정경한,박성원,최항석,이충원,이인모 한국지반공학회 2008 한국지반공학회논문집 Vol.24 No.4
Pressurized grouting is a common technique in geotechnical engineering applications to increase the stiffness and strength of the ground mass and to fill boreholes or void space in a tunnel lining and so on. Recently, the pressurized grouting has been applied to a soil-nailing system which is widely used to improve slope stability. Because interaction between pressurized grouting paste and adjacent ground mass is complicated and difficult to analyze, the soil-nailing design has been empirically performed in most geotechnical applications. The purpose of this study is to analyze the ground behavior induced by pressurized grouting paste with the aid of laboratory model tests. The laboratory tests are carried out for four kinds of granitic residual soils. When injecting pressure is applied to grout, the pressure measured in the adjacent ground initially increases for a while, which behaves in the way of the membrane model. With the lapse of time, the pressure in the adjacent ground decreases down to a value of residual stress because a portion of water in the grouting paste seeps into the adjacent ground. The seepage can be indicated by the fact that the ratio of water/cement in the grouting paste has decreased from a initial value of 50% to around 30% during the test. The reduction of the W/C ratio should cause to harden the grouting paste and increase the stiffness of it, which restricts the rebound of out-moved ground into the original position, and thus increase the in-situ stress by approximately 20% of the injecting pressures. The measured radial deformation of the ground under pressure is in good agreement with the expansion of a cylindrical cavity estimated by the cavity expansion theory. In-situ test revealed that the pullout resistance of a soil nailing with pressurized grouting is about 36% larger than that with regular grouting, caused by grout radius increase, residual stress effect, and/or roughness increase.