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Antioxidant Activity of the Chemical Constituents from the Flower Buds of Magnolia denudata
Youngwan Seo 한국생물공학회 2010 Biotechnology and Bioprocess Engineering Vol.15 No.3
The scavenging activity of the flower buds of Magnolia denudata Desrousseaux on reactive oxygen species (ROS) was evaluated using 2',7'-dichlorofluorescin diacetate (DCFH-DA) in HT 1080 cells. Methanol (MeOH)and dichloromethane (CH2Cl2) extracts inhibited dosedependently generation of ROS in the cellular system. MeOH and CH2Cl2 extracts were combined and fractionated with n-hexane, 85% aqueous MeOH, and n-butanol (n-BuOH). Both n-hexane-soluble and 85% aqueous-soluble fractions showing strong radical-scavenging activity in the cellular system were further separated by diverse chromatographic methods to give five known lignans (1-5). All these compounds exhibited significant radical-scavenging effect on intracellular ROS in a dose-dependent manner. Their scavenging activity on various reactive oxygen species (ROS) was also evaluated using electron spin resonance (ESR) spin-trap techniques.
서영완,이희정,차효준,김유아,박기의 韓國海洋大學校 附設 海洋科學技術硏究所 2002 硏究論文集 Vol.11 No.2
The antioxidant activity of methanol and dichloromethane extracts of salt marsh plants was tested by using 1,1-Diphenyl-2-picryl-hydrazyl(DPPH). Three salt marsh plants (Erigeron annuus, Ixeris tamagawaensis kitamura, Portulaca oleracea) were found to be significantly effective in DPPH radical scavenging activity. The combined crude extracts of Portulaca oleracea were sequentially partitioned with n-hexane, 15% aq. MeOH, EtOAc, n-BuOH and H_2O. the antioxidative activities of several fractions were determined by evaluation the DPPH radical scavenging effect and by measuring lipid peroxide using 2-thiobarbituric acid (TBA). Among them, remarkable antioxidative effects were observed in the fractions of EtOAc and n-BuOH. The DPPH radical scavenging effect (IC_50=17.90㎍/ml) of the n-BuOH soluble fraction was comparable with that of natural antioxidant, a-tocopherol (IC_50=6.99㎍/ml).
Building a HOG Descriptor Model of Pedestrian Images Using GA and GP Learning
Youngwan Cho,Kisung Seo 한국지능시스템학회 2018 INTERNATIONAL JOURNAL of FUZZY LOGIC and INTELLIGE Vol.18 No.2
For detecting a pedestrian by using features of images, it is generally needed to establish a reference model that is used to match with input images. The support vector machine (SVM) or AdaBoost Cascade method have been generally used to train the reference pedestrian model in the approaches using the histogram of oriented gradients (HOG) as features of the pedestrian model. In this paper, we propose a new approach to match HOG features of input images with reference model and to learn the structure and parameters of the reference model. The Gaussian scoring method proposed in this paper evaluates the degree of feature coincidence with HOG maps divided with angle of the HOG vector. We also propose two approaches for leaning of the reference model: genetic algorithm (GA) based learning and genetic programming (GP) based learning. The GA and GP are used to search the best parameters of the gene and nonlinear function representing feature map of pedestrian model, respectively. We performed experiments to verify the performance of proposed method in terms of accuracy and processing time with INRIA person dataset.
Endogenous Growth and South-North Trade
Goo, Youngwan,Lee, Seonghoon 세종대학교 국제경제연구소 2002 Journal of Economic Integration Vol.17 No.3
In this atricle, we develop an endogenous growth model to analyze the impact of knowledge spillovers, the disparity in initial endowments and production technologies on economic growth of two trading regions. We found that the growth rates of technology development of the two regions become uneven unless they have an identical initial steady-state labor allocation between technology development and intermediate inputs. Trade in intermediate goods and knowledge spillovers improve welfare in both regions.
Building a HOG Descriptor Model of Pedestrian Images Using GA and GP Learning
Cho, Youngwan,Seo, Kisung Korean Institute of Intelligent Systems 2018 INTERNATIONAL JOURNAL of FUZZY LOGIC and INTELLIGE Vol.18 No.2
For detecting a pedestrian by using features of images, it is generally needed to establish a reference model that is used to match with input images. The support vector machine (SVM) or AdaBoost Cascade method have been generally used to train the reference pedestrian model in the approaches using the histogram of oriented gradients (HOG) as features of the pedestrian model. In this paper, we propose a new approach to match HOG features of input images with reference model and to learn the structure and parameters of the reference model. The Gaussian scoring method proposed in this paper evaluates the degree of feature coincidence with HOG maps divided with angle of the HOG vector. We also propose two approaches for leaning of the reference model: genetic algorithm (GA) based learning and genetic programming (GP) based learning. The GA and GP are used to search the best parameters of the gene and nonlinear function representing feature map of pedestrian model, respectively. We performed experiments to verify the performance of proposed method in terms of accuracy and processing time with INRIA person dataset.
적응적인 휴머노이드 보행을 위한 CPG 궤적 및 GP 관절 보정의 결합 기법
조영완(Youngwan Jo),김훈이(Hunlee Kim),서기성(Kisung Seo) 대한전기학회 2016 전기학회논문지 Vol.65 No.9
A combined CPG (Central Pattern Generator) based foot trajectory and GP (Genetic Programming) based joint compensation method is presented for the adaptive humanoid walking. The CPG based foot trajectory methods have been successfully applied to basic slops and variable slops with slow rates, but have a limitation for the steep slop terrains. In order to increase an adaptability of humanoid walking for the rough terrains, a GP based joint compensation method is proposed and combined to the CPG (Central Pattern Generator) based foot trajectory method. The experiments using humanoid robot Nao are conducted in an ODE based Webots simulation environmemt to verify a stability of walking for the various aslope terrains. The proposed method is compared to the previous CPG foot trajectory technique and shows better performances especially for the steep varied slopes.