• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 B
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• pp.1122-1124
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• 1993

In this study, piezoceramics/polymer composites with 3-3 connectivity were made by BURPS(Burnout Plastic Sphere) technique with PZT ceramics and PVA sphere. And physical and dielectric properties dependent on the PVA wt.% were investigated. The density of porous piezoceramic and pieaoceramic/polymer composites were decreased almost linearly with increasing the PVA wt.%.

• 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.

• 한국재료학회지
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• 제32권11호
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• pp.508-514
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• 2022

Piezoelectric composite films which are enabled by inorganic piezoelectric nanomaterials-embedded polymer, have attracted enormous attention as a sustainable power source for low powered electronics, because of their ease of fabrication and flexible nature. However, the absorption of applied stress by the soft polymeric matrices is a major issue that must be solved to expand the fields of piezoelectric composite applications. Herein, a flexible and porous piezoelectric composite (piezoelectric sponge) comprised of BaTiO₃ nanoparticles and polydimethylsiloxane was developed using template method to enhance the energy conversion efficiency by minimizing the stress that vanishes into the polymer matrix. In the porous structure, effective stress transfer can occur between the piezoelectric active materials in compression mode due to direct contact between the ceramic particles embedded in the pore-polymer interface. The piezoelectric sponge with 30 wt% of BaTiO₃ particles generated an open-circuit voltage of ~12 V and a short-circuit current of ~150 nA. A finite element method-based simulation was conducted to theoretically back up that the piezoelectric output performance was effectively improved by introducing the sponge structure. Furthermore, to demonstrate the feasibility of pressure detecting applications using the BaTiO₃ particles-embedded piezoelectric sponge, the composite was arranged in a 3 × 3 array and integrated into a single pressure sensor. The fabricated sensor array successfully detected the shape of the applied pressure. This work can provide a cost-effective, biocompatible, and structural strategy for realizing piezoelectric composite-based energy harvesters and self-powered sensors with improved energy conversion efficiency.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2013년도 춘계학술대회 논문집
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• pp.1211-1212
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• 2013

• 한국고분자학회지:고분자과학과기술
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• 제10권6호
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• pp.722-731
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• 1999

• 한국기계가공학회지
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• 제14권5호
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• pp.126-133
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• 2015

Recently, there has been demand for polymeric porous membranes in various fields, such as environmental engineering, pharmaceutics, tissue engineering, drug delivery, biology, and fuel cells. In this study, it is proposed that a polymer particle-based porous membrane can be fabricated using electrospraying and sintering processes. Electrospraying can fabricate polymeric particles with diameters ranging from several micrometers to tens of nanometers without the cumbersome particle aggregation problem. Additionally, the particles can be sintered through thermo-compression under the glass transition temperature. In this study, a polymethyl methacrylate particle-based porous membrane with an average pore size of less than 500 nm is fabricated using the proposed method.

• Bulletin of the Korean Chemical Society
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• 제35권1호
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• pp.293-296
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• 2014

• 폴리머
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• 제24권4호
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• pp.453-458
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• 2000

이미다졸-금속 이온 구조를 갖는 고분자 Langmuir-Blodgett (LB)막과 이들의 캐스트막을 다공성막 필터 위에 제조하여 산소와 질소의 투과성을 비교 검토하였다. 양친성 고분자 폴리 (N-(2-(4-이미다졸일)에틸)말레이미드-alt-1-옥타데센) (IM-O)은 폴리 (무수말레산-alt-1-옥타데센)과 히스타민의 반응으로 합성되었다. IM-O 단분자층은 철(III) 이온을 갖는 하층액 위에서 매우 안정하였다. LB막의 분자 구조는 FT-IR을 통하여 결정하였으며, LB막내에 존재하는 금속 이온의 농도는 XPS 측정으로 분석하였다. LB막의 균일성과 안정성을 SEM 관찰을 통하여 간접적으로 평가하였다. 본 LB막과 캐스트막의 기체 선택성은 산소보다 질소가 약간 높게 나타났으며, 두 기체에 대하여 모두 고투과성을 나타냈다.

• 공업화학
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• 제9권2호
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• pp.311-316
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• 1998

물리 화학적인 특성이 다른 다공성 고분자 마이크로겔에 대한 bovine serum albumin (BSA-protein) 단백질의 흡착평형 특성을 연구하였다. 수용액 속에서 고분자와 단백질사이의 소수성 상호작용에 의하여 폴리부틸메타크릴레이트 (PBMA) 마이크로겔이 폴리비닐피리딘 (PVP)과 폴리아크릴로니트릴 (PAN) 마이크로겔보다 높은 흡착특성을 나타내었으며, PBMA 마이크로겔이 PVP와 PAN 마이크로겔보다 비가역적으로 흡착평형 특성을 나타내었다. 그러므로 고분자 마이크로겔의 물리적인 특성과 단백질-고분자 마이크로겔 사이의 정전기적 인력보다는 소수성 상호작용이 단백질의 흡착특성에 중요한 역할을 하고 있음을 알 수 있다. 또한 PBMA, PVP 및 PAN 마이크로겔 모두 Freundlich 흡착 등온식보다는 Langmuir 흡착 등온식에 잘 적용되었다.

• 폴리머
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• 제37권5호
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• pp.649-655
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• 2013

방사선 그래프팅 방법을 이용하여 다공성 PTFE 지지체에 친수성 고분자 사슬인 아크릴산 사슬을 도입시켜 강화 복합 연료전지막의 지지체로 사용하기 위한 PTFE 친수화 다공성 지지체를 제조하였고 FTIR을 이용하여 다공성 PTFE에 친수성 고분자가 성공적으로 도입되었음을 확인하였다. 제조된 지지체의 표면 친수화 정도를 관찰하기 위해 접촉각을 측정한 결과, 도입된 친수성 고분자 사슬이 증가할수록 소수성의 PTFE 표면 친수화도가 증가됨을 확인하였다. 또한 제조된 지지체의 물리화학적, 형태학적 특성은 FE-SEM, gurley number, 인장강도를 측정하여 관찰하였다.