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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.
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.
낮은 압축력을 받는 철근콘크리트 기둥의 내진성능에 대한 띠철근 상세의 영향
김철구,박홍근,엄태성,김태완 한국지진공학회 2015 한국지진공학회논문집 Vol.19 No.4
Various non-seismic tie details are frequently used for one- and two-story small buildings because the seismic demand on their deformation capacities is not relatively significant. To evaluate the effects of the non-seismic tie details on the seismic performance of reinforced concrete columns, six square columns with a cross section of 400 × 400 mm and six rectangular columns with a cross section of 250 × 640 mm were tested. The anchorage details at both ends and spacing of tie hoops, along with the cross-sectional shape and the magnitude of axial load, were considered as the primary test parameters. Test results showed that square columns had higher stiffness and lower lateral deformation rather than rectangular columns. Both lap spliced tie and U-shaped tie provided comparable or improved seismic performance to 90° hook tie in terms of maximum strength, ductility, and energy dissipation. The predicted curves with modeling parameters in ASCE41-13 were conservative for test results of lap spliced tie and U-shaped tie specimens since plastic behavior after flexural yielding could not be considered. For economical design, ASCE41-13 should be revised with various test results of tie details.
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.
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.