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Orientation Control of Chromonic Nano Columns via Capillary Bridge
윤희성,윤동기 한국고분자학회 2021 한국고분자학회 학술대회 연구논문 초록집 Vol.46 No.1
Well-ordered chromonic nano columns composed of 1D aggregates of disc-shaped molecules in water are widely used for sensor, display, and biotechnology. Commonly, chromonic nano columns have been controlled to 1D or 2D self-assembled structure with surface modification. However, it has limitation to fabricate complex 3D structures that can be used in chiral applications with previous methods. Here, we suggested a new approach to assemble chromonic nano columns from 1D to 3D structures via the capillary bridge. When chromonic solution is injected into microcavity composed with patterned microchannel and glass substrates, capillary bridge is spontaneously generated due to inhomogeneous capillary action. Various structures of nano columns from 1D to 3D are spontaneously generated by adjusting the effect of interface of capillary bridge. This simple method can control the nano columns in large area and be applied on chiral application which have not been accessed with conventional methods.
Therapeutic Effect of Glucosamine on an Atopic Dermatitis Animal Model
윤희성,변지원,신정현,김영효,최광성 대한피부과학회 2019 Annals of Dermatology Vol.31 No.5
Background: Recent studies have reported that glucosamine (GlcN) showed therapeutic effects in allergic diseases such as asthma and rhinitis, and its mechanisms include the suppression of T helper type 2 immune responses and the nuclear factor-κB pathway. Objective: We aimed to investigate the effect of GlcN on atopic dermatitis (AD) in an animal model. Methods: Twenty-five BALB/c mice were divided into five groups (groups A∼E). Group A was the phosphate- buffered saline (PBS)-treated group without AD induction. Group B was the PBS control group with AD induction. Groups C to E were the AD induction groups, which were treated with three different doses of GlcN (10 mg, 20 mg, and 40 mg, respectively). Histopathological examination was performed after GlcN administration. Interleukin (IL)-4, IL-13, and IL-17 cytokine levels were measured by enzyme- linked immunosorbent assay using skin biopsy specimens. Serum total immunoglobulin E (IgE) concentrations were measured before and after administration with GlcN or PBS. Results: Clinical dermatitis scores decreased with increasing GlcN dose (p<0.001). Concentrations of tissue IL-13 and IL-17 decreased after GlcN administration (each group: p=0.002 and p<0.001, respectively), but the concentrations of tissue IL-4 did not show differences across groups. Serum IgE levels tended to be lower after GlcN administration (p=0.004). Histopathological scores were not significantly different among groups B∼E (p=0.394). Conclusion: GlcN improved AD symptoms and decreased tissue IL-13, IL-17, and serum total IgE levels in an animal model.
Trading Strategies in Bulk Shipping: the Application of Artificial Neural Networks
윤희성,임상섭,이기환 한국항해항만학회 2016 한국항해항만학회지 Vol.40 No.5
The core decisions of bulk shipping businesses can be summarized as the timing and the choice of period for which carrying capacity is traded. In particular, frequent decisions to trade freight either with repeated spot transactions or with a one-off long-term deal critically impact business performance. Even though a variety of freight trading strategies can be employed to facilitate the decisions, chartering practitioners have not been active in utilizing these strategies, and academic research has rarely proposed applicable solutions. The specific properties of freight as a tradable commodity are not properly reflected in existing studies, and limitations have been reported in their application to the real world. This research focused on the establishment of applicable freight trading strategies by taking into account two properties of freight: time perishability and term-dependant pricing. In addition to traditional trading strategies, artificial neural networks were applied for the first time to the test of freight trading strategies. The performances of the trading strategies were measured and compared to produce a remarkable outperformance of the ANN. This research is expected to make a significant contribution to chartering practices by enhancing the quality of chartering decisions and eventually enabling the effective management of freight rate risk. In addition to methodological expansion, the result will propose a way to approach the controversial issue of freight market efficiency.