• 한국막학회:학술대회논문집
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• 한국막학회 2005년도 춘계 총회 및 학술발표회
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• pp.83-84
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• 2005

• 한국고분자학회지:고분자과학과기술
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• 제21권5호
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• pp.459-465
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• 2010

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.42-43
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• 2006

We have prepared random, block and graft copolymers with single or dual sensitivities to various stimuli. We have conjugated these polymers to proteins at random lysine sites or at specific sites designed into the protein by genetic engineering. We are also grafting the smart polymers to the surfaces of nanobeads. We are applying these smart conjugates and smart nanobeads in microfluidic devices for various applications, including diagnostics, affinity separations and enzyme bioprocesses. In this talk I will update our work with these interesting hybrid systems.

• 한국토양비료학회지
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• 제46권6호
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• pp.458-462
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• 2013

A drainage ditch is normally a component of drainage networks in farming systems to remove surplus water, but at the same time, it may act as a major conduit of agricultural nonpoint source pollutions such as sediment, nitrogen, phosphorus, and so on. The hybrid turbidity reduction system using biodegradable check dam and synthetic polymer was developed in this study to manage pollutant discharge from agricultural farmlands during rainfall events and/or irrigation periods. The performance of this hybrid system was assessed using a laboratory open channel sized in 10m-length and 0.2m-width. Various check dams using agricultural byproducts (e.g., rice straw, rice husks, coconut fiber and a mixture of rice husks and coconut fiber) were tested and additional physical factors (e.g., channel slope, flowrate, PAM dosage, turbidity level, etc.) affecting on turbidity reduction were applied to assess their performance. A series of lab experiments clearly showed that the hybrid turbidity reduction system could play a significant role as a supplementary of Best Management Practice (BMP). Moreover, the findings of this study could facilitate to develop an advanced BMP for minimizing nonpoint source pollution from agricultural farmlands and ultimately to achieve the sustainable agriculture.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2009년도 추계학술발표대회
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• pp.12.1-12.1
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• 2009

Nano-hydroxyapatite (N-HAp)has shown the pivotal role in producing bone-regenerative materials since it has similarity to natural bone minerals in terms of size, morphology, and the composition. Currently, the combination of biopolymers and N-HAp is recognizedas an attractive approach in generating hybrid scaffolds for bone tissueengineering. Surface engineering is an important issue since it determines whether cells can effectively adhere and proliferate on porous scaffolds. We aim to develop a synthetic approach to porous 3D scaffolds by immobilizing N-HAp on pore surfaces. The discrete nano-level anchoring of N-HAp on the scaffold pore surface is achieved using surface-repellent stable colloidal N-HAp with surface phosphate functionality. This rational surface engineering enables surface-anchored N-HAp to express its overall intrinsic bioactivity,since N-HAp is not phase-mixed with the polymers. The porous polymer scaffolds with surface-immobilized N-HAp provide more favorable environments thanconventional bulk phase-mixed polymer/N-HAp scaffolds in terms of cellular interaction and growth. In vitro biological evaluation using alkalinephosphatase activity assay supports that immobilized N-HAp on pore surfaces of polymer scaffolds contributed to the more enhanced in vitro osteogenicpotential. Besides, the scaffolds with surface-exposed N-HAp provide favorable environments for enhanced in vivo bone tissue growth, estimated by characteristic biomarkers of bone formation such as collagen. The results suggest that newly developed hybrid scaffolds with surface-immobilized N-HApmay serve as a useful 3D substrate with pore surfaces featuring excellent bonetissue-regenerative properties. Acknowledgement. This research was supported by a grant (code #: 2009K000430) from 'Center for Nanostructured Materials Technology' under '21st Century Frontier R&D Programs' of the Ministry of Education, Science and Technology, Korea.

• 폴리머
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• 제37권5호
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• pp.587-591
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• 2013

Poly(3,4-ethylenedioxythiophene)(PEDOT)은 높은 전기 전도도, 광학적 투과성 및 좋은 화학적 안정성을 가지고 있는 반면 낮은 물리화학적 물성을 가지고 있다. 본 연구의 목적으로 PEDOT의 내용제성 및 필름경도와 같은 물리화학적 특성을 향상시키고자 하였다. 음이온성 수성폴리우레탄(WPU)이 가지는 카르복실기는 아지리딘 존재 하에서 효과적인 가교반응이 일어나 물리화학적 특성이 개선된 WPU/PEDOT 혼성 전도성 박막을 제조할 수 있다. 다양한 WPU 및 고형분 함량별로 WPU/PEDOT 유기-유기 혼성 박막을 제조하여 전기적/물리화학적 특성을 비교하였다. 고형분 함량이 증가할수록 투과율과 표면저항은 감소하였다. WPU/PEDOT 혼성 전도성 박막의 연필경도와 내용제성이 WPU가 가지는 카르복실기의 가교반응에 인해 효과적으로 증가하였다.

• Tissue Engineering and Regenerative Medicine
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• 제15권6호
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• pp.673-697
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• 2018

BACKGROUND: Cartilage tissue engineering (CTE) aims to obtain a structure mimicking native cartilage tissue through the combination of relevant cells, three-dimensional scaffolds, and extraneous signals. Implantation of 'matured' constructs is thus expected to provide solution for treating large injury of articular cartilage. Type I collagen is widely used as scaffolds for CTE products undergoing clinical trial, owing to its ubiquitous biocompatibility and vast clinical approval. However, the long-term performance of pure type I collagen scaffolds would suffer from its limited chondrogenic capacity and inferior mechanical properties. This paper aims to provide insights necessary for advancing type I collagen scaffolds in the CTE applications. METHODS: Initially, the interactions of type I/II collagen with CTE-relevant cells [i.e., articular chondrocytes (ACs) and mesenchymal stem cells (MSCs)] are discussed. Next, the physical features and chemical composition of the scaffolds crucial to support chondrogenic activities of AC and MSC are highlighted. Attempts to optimize the collagen scaffolds by blending with natural/synthetic polymers are described. Hybrid strategy in which collagen and structural polymers are combined in non-blending manner is detailed. RESULTS: Type I collagen is sufficient to support cellular activities of ACs and MSCs; however it shows limited chondrogenic performance than type II collagen. Nonetheless, type I collagen is the clinically feasible option since type II collagen shows arthritogenic potency. Physical features of scaffolds such as internal structure, pore size, stiffness, etc. are shown to be crucial in influencing the differentiation fate and secreting extracellular matrixes from ACs and MSCs. Collagen can be blended with native or synthetic polymer to improve the mechanical and bioactivities of final composites. However, the versatility of blending strategy is limited due to denaturation of type I collagen at harsh processing condition. Hybrid strategy is successful in maximizing bioactivity of collagen scaffolds and mechanical robustness of structural polymer. CONCLUSION: Considering the previous improvements of physical and compositional properties of collagen scaffolds and recent manufacturing developments of structural polymer, it is concluded that hybrid strategy is a promising approach to advance further collagen-based scaffolds in CTE.

• 폴리머
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• 제31권1호
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• pp.86-91
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• 2007

Polydimethylsiloxane prepolymer와 2-hydroxyethyl methacrylate (HEMA)를 이용하여 Polydimethylsiloxane을 도입한 HEMA(SH)를 제조하였다. 여기에 methacrylic acid (MA), allyl glycidyl ether(AGE) 및 aminopropyltrimethoxysilane (APTS)를 이용하여 실록산 변성 polyacrylate hybrid(SMPA)를 제조하고 이들의 구조를 FTIR 및 $^1H-NMR$로 확인하였다. SMPA에 대한 내열특성을 TGA를 통해 측정한 결과 $400^{\circ}C$에서 무게 잔존율($W_{tr}$, %)은 APTS의 함량이 증가할수록 55에서 63%로 증가하여 나타났다. 제조한 SMPA에 증점제, 가교제 등의 각종 첨가제들을 가하여 SMPA 실란트를 제조하였다. 접착특성을 측정한 결과 SMPA-3를 이용하여 제조한 실란트의 경우 concrete와 금속사이의 최대 하중 신장률은 2.01%. 파괴 하중 신장률은 2.28%로 SMPA-1 및 SMPA-2를 이용하여 제조한 실란트의 1.07, 1.45%와 1.02, 1.35%인 경우보다 증가되었다.

• 대한기계학회논문집A
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• 제41권2호
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• pp.137-142
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• 2017

최근 자동차 산업에서 경량화이면서 외부 충격에 민감한 시트 프레임은 안전성을 고려하여 꾸준히 연구개발되고 있다. 특히 본 연구에서는 고장력 강판과 폴리머의 이종 소재를 이용한 시트 프레임의 충격 특성에 대해 살펴보았다. 또한, 충격시 변위는 소재에 대해 굽힘 현상을 고려한 등가 굽힘강성식을 도입하여 살펴보았다. 층간 wire-web 구조물의 다양한 형상의 공학 디자인을 통해 충격시 변화가 적은 디자인을 설계하였으며, 육각형의 층간 wire-web 구조물이 외부 충격대비 안전계수가 높음으로 인해 흡수능력이 향상될 것으로 기대하고 있다. 이러한 연구 결과를 토대로 층간 wire-web 구조물의 설계를 통해 레진과의 함침을 높이고 이종 소재로써의 충격민감도에 유리한 제품을 개발할 수 있을 것으로 사료된다.

• 공업화학
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• 제25권6호
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• pp.581-585
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• 2014

Reduced graphene oxide (RGO)를 수용성 고분자인 poly(styrene sulfonate) (PSS)로 wrapping한 수분산성 그래핀 치환체인 G-PSS와 전도성 고분자인 poly(3,4-ethylenedioxythiophene)/poly(styrene sulfonate) (PEDOT/PSS)의 복합화에 관하여 연구하였다. G-PSS의 존재 하에서 PEDOT/PSS의 제자리 화학 중합 반응을 수행하여 복합체(GP)를 얻었다. 생성물의 XPS, IR 및 Raman 분석을 통하여 모노머인 EDOT의 중합이 원활하게 진행되어 PEDOT/PSS가 생성됨과 동시에 그래핀과 복합화되었다는 것을 확인할 수 있었다. 또한 GP는 $4.46{\times}10^2S/m$의 전도도를 나타냈으며, 0.5%의 농도까지 물에 분산이 되어 G-PSS보다 전기적 특성 및 수분산성 모두 우수하였다.