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Novel Cyclodextrin Functionalized Agarose Hydrogel for Effective Drug Delivery System
김철구,정다함,정선호 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.1
Agarose-based hydrogels are used for three-dimensional culture of human and animal cells and are widely used in drug delivery systems. However, the high gelation temperature and high stiffness of agarose limits its applicability for various applications. In this study, β -Cyclodextrin (βCD) was introduced into agarose to control the mechanical properties of agarose and to develop a hydrogel with low gelation temperature. This synthetic CD-agarose (CFA) has a lower gelation temperature than conventional agarose, allowing for effective loading of the drug at room temperature. CFA gels could be used for complete release of bovine serum albumin and sustained release through inclusion complexation of βCD against doxorubicin. CFA is not cytotoxic and could be used in a variety of drug delivery systems.
김철구,박홍근,강수민 한국콘크리트학회 2020 콘크리트학회논문집 Vol.32 No.5
본 연구에서는 최적화된 댑단부를 적용한 더블티 슬래브 시스템의 현장 적용성을 검증하기 위하여 시공단계에서의 구조성능을 평가하였다. 댑단부 형상 및 전단보강 여부, 휨철근비, 전단경간비를 주요 변수로 댑단부의 전단실험과 PC 슬래브의 휨실험을 수행하였다. 실험결과를 살펴보면, 전단철근이 보강되지 않은 댑단부의 전단성능과 PC 슬래브의 휨성능은 콘크리트구조 학회기준으로 안전측으로 예측 가능하다. 댑단부의 절곡부 모서리에는 국부적으로 큰 응력이 발생하기 때문에 반드시 전단철근을 배근하여야 하며, 댑단부 전단철근은 스트럿-타이 모델로 설계 가능하다.
김철구,박홍근,김영문 한국콘크리트학회 2020 콘크리트학회논문집 Vol.32 No.3
고온고압 증기양생 기포 콘크리트(ALC)는 제작과정에서 기포제에 의해 내부에 기포가 형성되어 경량이고 열전도율이 낮아 단열성능이 우수하다. 하지만 ALC의 압축강도 및 인장강도가 일반콘크리트에 비해 크게 낮아서 횡력 저항시스템에 사용되기 위해서는 추가적인 보강이 필요하다. 본 연구에서는 비보강조적벽의 보강방법 중 하나인 TRM(textile reinforced mortar) 공법을 적용한 ALC 블록과 프리즘에 대한 휨인장 성능을 살펴보았다. ALC 블록의 보강재료로는 경제성이 우수한 GFRP(glass fiber reinforced polymer) 메쉬를 사용하였다. ALC 블록과 프리즘의 휨인장강도 시험결과, GFRP 메쉬는 휨 균열이 발생한 이후 인장력을 전달하여 최대 휨인장강도와 변형능력이 증가하였다. ALC 블록의 가로줄눈에 보강된 GFRP 메쉬는 모르타르 인장부착성능에는 큰 효과가 없었지만, 표면에 보강된 메쉬는 모르타르의 부착성능에 효과적이었다.
Microbial Carbohydrate Resource Bank
김철구,정선호 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.0
Microbial carbohydrates have a variety of characteristics and original functionalities comparing with carbohydrates produced by animals and plants. Microbial carbohydrates are natural, non-toxic and biocompatible polymers, GRAS(Generally Regarded As Safe) and their structural diversities lead to a variety of functions. Recently, many novel applications have been developed using microbial polysaccharides such as drug delivery systems, hydrogels, nanoparticles, and materials for tablet-pressing process in the pharmaceutical and biomedical industries as well as in the bio-nano engineering. The Microbial Carbohydrate Resource Bank (MCRB) was established to investigate and collect various functional polysaccharides and microorganisms in order to widely utilize the microbial resources. MCRB will contribute the advancement of industrial fields using carbohydrates and provide microbial resources into various researchers to encourage basic and applied researches.
김철구,박홍근,김태완,엄태성 한국지진공학회 2016 한국지진공학회논문집 Vol.20 No.6
In regions of low-to-moderate seismicity, various types of lap splices are used for longitudinal reinforcement of columns at the plastic hinge zones. The seismic performance of such lap spliced columns, such as strength, deformation capacity, and energy dissipation, is affected by material strengths, longitudinal re-bar size, confinement of hoops, lap splice location, and lap splice length. In the present study, cyclic loading tests were performed for columns using three types of lap splices (bottom offset bar splice, top offset bar splice, and splice without offset bend). Lap splice length(40db and 50db) was also considered as test parameters. Ties with 90-degree end hooks were provided in the lap splice length. The test results showed that strength, deformation capacity, and energy dissipation of columns significantly differed depending on the details and the length of lap splices. The bottom offset bar splice showed high ductility and energy dissipation but low strength; on the other hand, the top offset bar splice and the splice without offset bend showed high strength but moderate ductility and energy dissipation.