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폴리비닐알콜/셀룰로오스 트리아세테이트 전기방사 섬유 이중층에 의한 종이 강도 보강
정은수(Eunsue Jeong),신성철(Sungchul Shin),이제곤(Jegon Lee),윤혜정(Hye Jung Youn),현진호(Jinho Hyun) 한국펄프·종이공학회 2018 펄프.종이技術 Vol.50 No.4
Polyvinyl alcohol (PVA) and cellulose triacetate (CTA) polymer solutions were electrospun to form nanofibers and microfibers, respectively. The bilayer of nano/micro fibers was prepared by electrospinning PVA nanofibers on the paper followed by electrospinning CTA microfibers on the top of a PVA nanofiber layer. The structure of electrospun fibers was observed by FE-SEM and mechanical properties of electrospun layers and bilayers were characterized to investigate split resistance, tensile index, folding endurance, and reversible preservability. The strength of damaged paper could be restored by applying the PVA nanofiber/CTA microfiber bilayer to paper and the nano/micro bilayer was easily detached by the exposure to moisture for a short period of time.
인공 노화 종이에 전기방사된 폴리비닐알콜/셀룰로오스 트리아세테이트 섬유의 종이 보강 효과
정은수(Eunsue Jeong),신성철(Sungchul Shin),윤혜정(Hye Jung Youn),현진호(Jinho Hyun) 한국펄프·종이공학회 2018 펄프.종이技術 Vol.50 No.5
In this research, we tried to reinforce artificially aged paper by introducing polyvinyl alcohol (PVA)/cellulose triacetate (CTA) double layers through electrospinning. The electrospinning conditions of PVA and CTA were established, and the morphological features of the electrospun fibers were observed by scanning electron microscopy. The aged paper showed the decrease of tensile strength and the folding endurance, but the mechanical properties were effectively increased by the introduction of the electrospun layers. The electrospinning of polymers formed a stable and fibrous reinforcing layer at the paper surface without the use of liquid adhesives. It would be advantageous in the conservation protocol because it could minimize the inevitable deformation of paper in the drying process or contamination by the additive materials.
알지네이트를 이용한 셀룰로오스 하이드로겔의 투과 특성 제어
정은수(Eunsue Jeong),신성철(Sungchul Shin),박민성(Minsung Park),현진호(Jinho Hyun) 한국펄프·종이공학회 2015 펄프.종이기술 Vol.47 No.2
Natural cellulose hydrogel membrane cannot be directly used for cell encapsulation because it has many large pores on the surface that immune biomolecules are able to penetrate into easily. For the reason, alginate was used for the control of pore size of the cellulose hydrogel membrane. The surface morphology of cellulose/alginate nanocomposite confirmed the successful control of the porosity of the membrane. The permeability of the cellulose/alginate nanocomposite was decreased but mechanical properties were increased compared with the bacterial cellulose membrane. The cellulose/alginate nanocomposite could be used for the functional membrane as a promising biomedical material in the future.
최은수(Choe, Eunsu),김정렬(Kim, Jeong-ryeol) 미래영어영문학회 2016 영어영문학 Vol.21 No.3
The primary purpose of this study is to analyze the integrated tasks in elementary school English textbooks on the basis of the 2009 National Curriculum in terms of task features. In order to accomplish this purpose, five elementary school English textbooks are selected. The integrated tasks in these textbooks are analyzed from the perspective of Task-Based Language Teaching. The results of the study indicate that, firstly, the five authorized elementary school English textbooks incorporate integrated tasks in each unit. However, the ‘role-play’ type integrated task features most prominently for 3<SUP>rd</SUP> and 4<SUP>th</SUP> graders, whereas the ‘project’ type is the most frequent task for 5<SUP>th</SUP> and 6<SUP>th</SUP> graders. This demonstrates that various types of integrated tasks are required for elementary school learners. Secondly, most of the integrated tasks are designed as two-way tasks that require information exchange. In terms of the input and the product that results from completing the task, the integrated tasks for 3<SUP>rd</SUP> and 4<SUP>th</SUP> graders focus more on spoken language skills, whereas the tasks presented for 5<SUP>th</SUP> and 6<SUP>th</SUP> graders tend to focus on developing written language skills. Based on the findings of the study, it is suggested that any English textbooks to be developed in the future should include multiple types of integrated tasks. Diversifying the types of tasks presented to the students will facilitate the cognitive processes. This will also provide various meaningful, goal-oriented communicative opportunities as well as promote fuller coverage of all four of the language skills.