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효소에 의한 아스트라갈린의 합성에 있어서의 정제 공정에 관한 연구
정대원 水原大學校 2013 論文集 Vol.27 No.-
Astragalin (AS), kaempferol monoglycoside, is classified as a polyphenol, and a minute quantity of AS is known to be present in several plants. Recently, it was reported to be able to prepare AS by the partial hydrolysis of camelliaside A (CamA) and camelliaside B (CamB) contained in tea seed extract (TSE), in the presence of a commercial enzyme complex such as Mash. In this paper, the processes for the recovery of product and the purification of AS were optimized in the enzymatic reaction of CamA and CamB in TSE. Double extractions of reaction mixture with tetrahydrofuran and the following recryatallization from methanol afforded AS with over 97% purity.
우레탄 결합을 통하여 개질된 클레이의 합성에 관한 연구
정대원 수원대학교 산업기술연구소 2004 산업기술연구소논문집 Vol.19 No.-
Commercially available clays were reacted with diisocyanate and followed by hexadecanol to prepare organo-clay (MMT-UR) bonded with long alkyl chain via urethane bond. MMT-UR was characterized by IR, XRD and TGA, and showed larger basal distance compared to any clays reported. However, no further intercalation was observed when MMT-UR was compounded with PP- MA.
ON QUANTITATIVE TWO WEIGHT ESTIMATES FOR SOME DYADIC OPERATORS
정대원 영남수학회 2022 East Asian mathematical journal Vol.38 No.3
In this paper, a comparison of two types of quantitative two weight conditions for the boundedness of the dyadic paraproduct and the commutator of the Hilbert transform is provided. In the case of the com- mutator [b, H], the conditions of the well-known Bloom’s inequality [2] and the slightly different types of two weight inequality introduced in [1] are compared around the A2-conditions on weights and the novel conditions on the function b .
Two Weight Estimate for the Paraproduct in the Space of Homogeneous Type
정대원 영남수학회 2019 East Asian mathematical journal Vol.35 No.3
In this paper, we provide sufficient conditions of a pair of weights (u, v) and a function b so that the dyadic paraproduct is bounded from L2u(X) into L2v(X), where X is a space of homegeneous type. In order to prove the main result we use the honest dyadic system introduced in [10].
지용성 β-sitosterol 치환제의 합성 및 콜레스트롤 저하 효과
정대원 수원대학교 산업기술연구소 1998 산업기술연구소논문집 Vol.13 No.-
β-sitosteryl oleate was synthesized by transesterification reaction of β-sitosterol with methyl oleate. Total cholesterol values of male rats fed with high cholesterol diet were significantly decreased by administration of β-sitosteryl oleate. It was possible to dissolve β-sitosteryl oleate in oils by formulation with methyl oleate.
클레이의 Silane Coupling Agent 처리에 관한 연구
정대원 水原大學校 2004 論文集 Vol.22 No.-
Natural clay(sodium-montmorillonite) and commercially available organo-clays were reacted with silane coupling agent (SCA) to improve the hydrophobicity of clays. This reaction was found to be very sensitive to many factors such as reaction temperature, water content and the concentration of SCA in reaction medium. In some cases, siloxane groups(Si-O-Si) were also produced by intermolecular cross-linking among SCAB. Organo-clays modified with SCA were compounded with PP-MA, however, no further intercalation was observed.
Robust H control synthesis for a turbo-generator system; LMI approach
정대원 湖南大學校 情報通信硏究所 1999 정보통신연구 Vol.9 No.-
본 논문은 H 제어 기법을 적용하여 전력계통의 소신호 안정도를 향상 시키기위한 전력계통 안정화 장치(PSS)의 설계기법에 대하여 논하였다. 전력계통은 예측하기 어려운 불확실성이 상존하는 상태에서 항상 운전되므로 계통의 동특성 안정도를 향상 시키기 위한 노력은 계통운용 측면에서 중요한 현안과제이다. 기존의 lead/lag의 이산 보상방법에 의한 PSS는 고정된 파라메터 상태로 동작함으로써 운전환경변화나 플랜트의 불확실성이 존재하는 환경에서는 응답이 효과적이지 못하다. 이에 견실성이 높은 H 제어 기법을 적용하여 새로운 설계기법을 시도하였다. 특히, H 노움의 최적화를 위하여 기존에 주로 사용하던 2개의 Riccati 대수방정식의 해법을 탈피하여 선행행렬부등식(LMI)의 볼록함수 최적화방법을 적용함으로써 전역에서의 최적해와 γ값을 구할 수가 있었다. 설계된 결과는 시뮬레이션을 통하여 그 성능을 기존의 lead/lag 필터형 PSS와 비교 평가할 수 있었고 보다 우수한 제어 성능을 얻을 수 있었다.