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590MPa급 고강도강의 성형 시 스프링백 예측 정확도에 미치는 판재이방성의 영향
박세계,백응률,박노근 대한금속·재료학회 2018 대한금속·재료학회지 Vol.56 No.3
Material parameters, extracted from mechanical behavior in a uniaxial direction without considering anisotropy in the rolling direction, are commonly used when doing forming analysis. However, when these material parameters are used for the forming analysis of a material which has large anisotropy, inaccurate analysis results can be obtained. In this study, the material parameters of the Yoshida-Uemori model, 0°, 45°, 90° to the rolling direction were extracted. When we used the material parameters extracted from three directions, each according to their rolling directions, the accuracy of the springback prediction was increased. We analyzed the effect of material parameters on the accuracy of the springback prediction, using nine material parameters. As a result, it was found that ‘B-Y’ and ‘m’ affected the accuracy of the springback prediction the most. When we compared this result to other studies, it showed outstanding accuracy for sidewall curl prediction. This shows the importance of considering the anisotropy of steel sheet, to increase accuracy of the springback analysis.
박세계,신재학,정재희,이동윤,최동윤,유승화 한국고분자학회 2021 한국고분자학회 학술대회 연구논문 초록집 Vol.46 No.2
Surface functionalization of the intravascular catheter for minimally invasive surgery, must be performed due to the three critical issues: blood stream infection, thrombosis, and damage to blood vessels due to high friction. Currently, most of prior technologies can"t prevent the three aforementioned issues at once, and use material having potential side effects. Here, we suggest multi-functional coating that can simultaneously implement antimcrobial, antithrombotic activity and low friction by coating with O-carboxymethyl chitosan (CMC). Especially, the coating layer was prepared in a porous structure to give the catheter surface super hydrophilicity, which showed a synergistic effect due to the anti-adhesion of bacteria and thrombin along with the inherent properties of CMC. Furthermore, the porous CMC coated catheter had sufficient lubricity in water, coating durability and high trackability in simulated blood vessels, demonstrating that it can be applied in practice catheters.
Multi-functional Porous Polysaccharide Based Coating for Intravascular Catheters
박세계,신재학,정재희,이동윤,최동윤,유승화 한국고분자학회 2021 한국고분자학회 학술대회 연구논문 초록집 Vol.46 No.1
Intravascular catheters are commonly used medical devices for patients in order to hemodynamic monitoring, medication administration, etc. Intravascular catheterization have several critical issues such as damage of blood vessel due to high friction, blood stream infection, blood coagulation. Herein, we attempted to functionalized the surface of catheter using O-carboxymethyl chitosan (CMC) which is a polysaccharide possessing lubricity, antimicrobial and anticoagulant activity. The hydrophobic catheter surface was modified with acrylic acid by electron beam induced grafting, leading to strong interfacial adhesion between grafted polyacrylic acid and CMC. The CMC coating layer was fabricated as a porous structure using Poly ethylene glycol. As a result, the coated surface exhibited superhydrophilicity under specific fabrication conditions. Furthermore, the effects of various pore system on the performance of functional coated catheter surface were discussed.
Superhydrophobic, Antibacterial Air Filter via One-Step Coating Method
박세계,신재학,이병진,박정훈,김우진,이동윤,정재희,최동윤 한국고분자학회 2021 한국고분자학회 학술대회 연구논문 초록집 Vol.46 No.2
The spread of emerging infectious diseases via bioaerosols (airbone microrganisms), such as the COVID-19 pandemic, made it essentional to wear personal protective equipment such as a mask. The mask filter can capture bio-aerosols to prevent infiltration of the respiratory tract, but the attached microorganisms can multiply surrounding moisture and dust as nutrients and cause secondary infection. To overcome this issue, antibacterial activity that kills microorganisms on the filter surface is an essential property. We report a antibacterial mask filter with effectively produce visible light triggered biocidal ROS. In particular, dip-coated filter with rose bengal, a photosensitizer dye for ROS generation and hydrophobic octadecylamine binding to Si-Al sol together was realized superhydrophibicity by roughly formed filter surface into a flower-like structure. The biocidal properties of the coated filter were demonstrated by ROS production measurements and antibacterial performance.
정순영,박세계,김한도,이동윤,윤승화 한국탄소학회 2020 Carbon Letters Vol.30 No.2
A carbon fber reinforced thermoplastic (CFRTP) was irradiated with a high energy electron-beam. As a result, the ten�sile strength of high-density polyethylene (HDPE)-based CFRTPs was signifcantly improved by gradually increasing the electron-beam dose. It was confrmed that the adhesion between CF and HDPE was improved and the surface properties of CF and HDPE were readily modifed by electron-beam. It was verifed from spectroscopic analysis that various oxygen�containing functional groups were formed on the surface of CF and HDPE by irradiation and we believe that strong attrac�tive interactions took place among these functional groups at the interface of CFs and HDPE. Finally, it was conclusive that electron-beam irradiation provided two main efects on CFRTPs. One was cross-linking of thermoplastic resin for efcient load transfer from resin to CF and the other was formation of surface functional group and attractive interaction of these functional groups at the interface of fber and matrix. These two efects showed synergetic contribution to enhance the mechanical properties of CFRTP.