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정승원,한대석,김석중,전문진 한국미생물생명공학회 ( 구 한국산업미생물학회 ) 1996 한국미생물·생명공학회지 Vol.24 No.2
Tyrosinase는 식품의 효소적 갈변과 생체내에서 melanin 합성을 촉매하는 효소이다. 식용 가능한 tyrosinase 저해제의 발효생산을 통하여 melanin 합성을 저해하는 효과를 가지는 미백식품 소재를 개발하고자 현재 식품의 제조에 이용되고 있는 안전한 미생물을 대상으로 tyrosinase 저해능이 높은 균주를 선발하고 표고버섯을 주 배지원으로 발효시켜 저해제 생산의 적정조건에 대하여 연구하였다. 발효식품으로부터 분리된 NU-7을 tyrosinase 저해제 생산을 위한 발효균으로 선정하여 tyrosinase 저해제 생산 최적배지 조건을 확인한 결과 glucose가 3~20% 및 ammonium sulfate가 0~0.25%인 범위에서 균체량 증가에 따른 tyrosinase 저해제 생산능의 차이는 나타나지 않았으며, 무기질소원으로 첨가한 ammonium sulfate의 영향은 비교적 낮았다. 한편, 표고버섯(Lentinus edodes, Shiitake) 함량은 저해제 생산과 밀접한 관계를 나타내어 버섯함량(X)에 대한 저해제 생산량(Y)이 Y=-0.96X^2+13.07X+14.43의 상관식을 보였고, R value는 0.96으로 나타나 최적발효 조건을 위한 최소한의 배지는 표고버섯과 glucose 만으로도 가능한 것으로 판단되었다. 표고버섯을 이용한 발효액에서 곰팡이 독소로 알려진 아플라톡신은 검출되지 않았으며 따라서 이를 식용할 수 있는 가능성이 높은 것으로 판단되었다. Tyrosinase is an enzyme which catalyzes an enzymatic browning of some foods and in vivo synthesis of melanin. In order to produce natural and edible inhibitor of the enzyme which is expected to have whitening effect on melanogenesis, a microorganism was selected from fermented foods. It was named as NU-7, and cultured in mushroom (Lentinus edodes, Shiitake) media. Optimal media to produce tyrosinase inhibitor was formulated by varing nitrogen or carbon content. If glucose content was in a range of 3~20% and ammonium sulfate was in a range of 0~0.25%, production of inhibitor was independent of cell mass. Addition of ammonium sulfate as a nitrogen source had little effect on inhibitor production. Production of inhibitor (Y) was proportionally related to shiitake content (X) with a regression equation of Y=-0.96X^2+13.07X+14.43 (R=0.96). These results indicate that shiitake and glucose are necessary for the production of tyrosinase inhibitor. In the analysis of mycotoxin in culture broth, aflatoxin was not detected, suggesting that it would be probably edible.
Role of Caffeic Acid on Collagen Production in Nasal Polyp-Derived Fibroblasts
정승원,박일호,홍성문,조정선,문준혁,김태훈,이흥만 대한이비인후과학회 2014 Clinical and Experimental Otorhinolaryngology Vol.7 No.4
Objectives. Caffeic acids are known to have anti-oxidant, anti-inflammatory, immunomodulatory, and tissue reparative ef- fects. The purposes of this study were to determine the effect of caffeic acid on transforming growth factor (TGF) β1- induced myofibroblast differentiation and collagen production, and to determine whether caffeic acid is involved in the antioxidant effect in nasal polyp-derived fibroblasts (NPDFs). Methods. NPDFs were pretreated with caffeic acid (1–10 μM) for 2 hours and stimulated with TGF-β1 (5 ng/mL) for 24 hours. The expression of α-smooth muscle actin (SMA), collagen types I and III, and Nox4 mRNA was determined by a reverse transcription-polymerase chain reaction, and the expression of α-SMA protein was determined by actin ned by immunofluorescence microscopy. The amount of total soluble collagen production was analyzed by the Sircol collagen dye-binding assay. The reactive oxygen species (ROS) generated by NPDFs were determined using 2',7'-di- chlorfluorescein-diacetate. siNox4 was used to determine the effect of Nox4. Results. The expression of α-SMA and production of collagen were significantly increased following TGF-β1 treatment. In contrast, the level of expression of α-SMA and the level of production of collagen were decreased by pretreatment with caffeic acid. The activation of Nox4 and the subsequent production of ROS were also reduced by pretreatment with caffeic acid. The expression of α-SMA was prevented by inhibition of ROS generation with siNox4. Conclusion. Caffeic acid may inhibit TGF-β1-induced differentiation of fibroblasts into myofibroblasts and collagen produc- tion by regulating ROS.
A Case of Acute Idiopathic Thrombocytopenic Purpura Following Influenza B Virus Infection
정승원,강성희,강진한,마상혁 대한소아감염학회 2015 Pediatric Infection and Vaccine Vol.22 No.2
Virus-associated immune thrombocytopenic purpura (ITP) can occur following common viruses, but cases of ITP associated with influenza infection has seldom been reported. In this report we describe a previously healthy 5-year-old boy who admitted with fever, flu-like symptoms and a few bruises on both legs. Severe thrombocytopenia were found. Bone marrow aspirates and biopsy showed no abnormalities and results of coagulation tests were all in normal limit. Real-time polymerase chain reaction was positive for influenza B infection. The patient fully recovered with intravenous immunoglobulins and steroid therapy.
지능형 교육 시스템의 학습자 분류를 위한 Var iational Auto-Encoder 기반 준지도학습 기법
정승원,손민재,황인준 한국멀티미디어학회 2019 멀티미디어학회논문지 Vol.22 No.11
Intelligent tutoring system enables users to effectively learn by utilizing various artificial intelligence techniques. For instance, it can recommend a proper curriculum or learning method to individual users based on their learning history. To do this effectively, user’s characteristics need to be analyzed and classified based on various aspects such as interest, learning ability, and personality. Even though data labeled by the characteristics are required for more accurate classification, it is not easy to acquire enough amount of labeled data due to the labeling cost. On the other hand, unlabeled data should not need labeling process to make a large number of unlabeled data be collected and utilized. In this paper, we propose a semi-supervised learning method based on feedback variational auto-encoder(FVAE), which uses both labeled data and unlabeled data. FVAE is a variation of variational auto-encoder(VAE), where a multi-layer perceptron is added for giving feedback. Using unlabeled data, we train FVAE and fetch the encoder of FVAE. And then, we extract features from labeled data by using the encoder and train classifiers with the extracted features. In the experiments, we proved that FVAE-based semi-supervised learning was superior to VAE-based method in terms with accuracy and F1 score.