• Proceedings of the Korean Fiber Society Conference
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• 2003.04a
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• pp.143-145
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• 2003

전기방사에 의해 제조되는 나노 파이버웹은 섬유가 매우 가늘고, 기공이 미세하며 비표면적이 매우 커서 필터 및 전극재료에 적합한 산업용 소재이다. 나노 웹의 구조는 방사 용액의 농도, 방사 온도, 압력, 전압등 여러 변수들에 의해 영향을 받으며, 이 변수들의 구조에 미치는 영향들이 이론적, 실험적으로 많이 연구, 보고되어 있다 [1]. 그러나, 공정의 분석 및 제어에 대한 연구는 매우 드물며, 특히 대량 생산하에서의 품질 관리 시스템에 대한 연구는 전무한 실정이다. (중략)

• Clean Technology
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• v.24 no.3
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• pp.249-254
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• 2018

In order to improve the photo conversion efficiency (${\eta}$) of dye-sensitized solar cells (DSSCs), the electrospun $TiO_2$, $SiO_2$, $ZrO_2$ and $SnO_2$ nanofibers were added into the hydrothermally prepared $TiO_2$ nanoparticles for application to a photoelectrode for DSSCs. The $TiO_2$ nanofiber added photoelectrode exhibited a higher photo current density ($J_{sc}$) compared to the bare $TiO_2$ nanoparticles, which is caused from acceleration of the transfer of excited electron from dye molecule due to the nanofiber structure. The DSSCs with $SiO_2$ nanofibers shows a higher open circuit voltage ($V_{oc}$) of 0.67 V and the highest photo conversion efficiency was found to be 6.24%.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.83-83
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• 2010

산업이 고도화되는 과정에서 에너지의 고효율화를 위하여 고온, 고압 등의 극한환경 하의 공정이 불가결하며, 이에 따라 초미세분진인 나노 입자가 증가되고 있다. 이에 따라 해당 나노의 입자 처리를 위하여 다양한 용도에서의 고온 필터가 산업적으로 요구되고 있다. 본 연구에서는 디젤엔진 매연저감 후처리 장치, 소각로, 발전소 등의 미세 분진 포집 필터로서의 응용을 위해, 카본 파이버에 SiC 휘스커를 증착하는 실험을 진행하였다. 휘스커 증착 공정은 촉매없이 SiC 휘스커를 카본 파이버 위에 화학증착하였다. 휘스커 성장 시 증착 조건의 변화를 통하여 다양한 휘스커의 증착 형태 및 미세구조를 관찰하였다. 또한 높은 포집 효율 및 기체투과도를 갖추기 위해, 휘스커가 증착된 시편의 포집효율 및 기체투과도 향상을 위한 실험을 진행하였다. 해당 실험의 결과로, 증착된 필터는 70% 이상의 포집효율을 보이면서도 기체 투과도는 현재 상용화되어 있는 코디얼라이트보다 5배 이상 높았다. 또한 필터에 추가적인 SiC 침윤공정을 통하여 시편의 내산화성, 내마모성, 내열성 등의 특성이 향상됨을 확인하였다.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.3
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• pp.225-230
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• 2016

Since the development of anodic aluminum oxide (AAO), extensive studies have been conducted ranging from fundamental research to the applications of AAO. Most of the research on AAO structures have focused on well-aligned nanoporous structures fabricated under specific conditions. This study investigated fabricable AAO structures with anodization performed with various temperatures, electrical potentials, and basal plane surfaces. As a result, nanoporous and nanofibrous structures were fabricated. The nanopores were formed at a relatively lower temperature and potential, and the nanofibers were formed at a relatively higher temperature and potential regardless of the basal plane surface. The shape of the base surface was found to influence the structural arrangement in nanoporous morphologies. These interesting findings relating to new morphologies have the potential to broaden the possible applications of AAO materials.

• Composites Research
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• v.18 no.3
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• pp.31-37
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• 2005

In this work, poly(ethylene oxide) (PEO) nanofibers were fabricated by electrospinning to prepare the nanofibers-reinforced composites. And the PEO powders-impregnated composites were also prepared to compare the mechanical interfacial behaviors of the composites. Morphology and fiber diameter of PEO nanofibers were determined by SEM observation. Mechanical interfacial properties of the composites were investigated in fracture toughness $(K_{IC})$ and interlaminar shea. strength (ILSS) tests. As a result, the fiber diameter was decreased with increasing the applied voltage. And optimum condition for the fiber formation was 15 kV, resulting from increasing of jet instability at high voltage. The PEO-based nanofibers-reinforced epoxy composites showed the improvements of both $K_{IC}$ and ILSS, compared to the composites impregnated with PEO powders. These results indicated that the nanofibers had higher specific surface area and larger aspect ratio than those of the powders, which played an important role in improving the mechanical interfacial properties of the composites.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.137.1-137.1
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• 2011

올리빈 구조의 $LiFePO_4$ 정극 활물질은 $650^{\circ}C$에서 고상법으로 제조되었다. $LiFePO_4$의 전자전도도를 향상시키기 위하여 graphite nanofiber(GNF)를 각각 3wt%, 5wt%, 7wt%, 9wt% 첨가하여 $LiFePO_4$-C를 제조하였다. 제조된 분말의 입자 형태를 확인하기 위하여 X-ray diffraction(XRD)과 File Electronic Scaning Electromicroscopy(FE-SEM)를 측정하였다. XRD결과로부터 제조된 분말은 모두 순수한 결정 구조를 나타내었고 입자의 크기는 약 200nm였다. 5wt% GNF를 첨가한 $LiFePO_4$-C는 기타 첨가량에 비해 방전용량이 가장 높았다. 첫 사이클의 용량은 151.73mAh/g 나타났고 50 사이클 뒤에도 92% 이상을 유지하고 있었다. 첨가하지 않은 것에 비해 43% 증가하였다. $LiFePO_4$-C(3wt%), $LiFePO_4$-C(7wt%), $LiFePO_4$-C(9wt%)의 첫 사이클 방전용량은 각각 147.94mAh/g, 136.64mAh/g, 121.07mAh/g 나타났다. $LiFePO_4$-C(5wt%)에 비해 용량은 떨어쪘지만 순수한 $LiFePO_4$보다 많이 높았다. 임피던스 결과를 보면 기타 첨가량에 비해 $LiFePO_4$-C(5wt%)의 저항 제일 낮았다. 이는 충방전 결과와 일치하였다. graphite nanofiber의 첨가로 인하여 $LiFePO_4$ 정극 활물질의 전자전도도가 높아지고, 따라서 전기화학적 특성도 크게 향상되었다.

• Korean Chemical Engineering Research
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• v.46 no.1
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• pp.50-55
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• 2008

Carbon Nanotube (CNT) films were deposited with varying deposition temperature by RF plasma CVD on Fe catalysts deposited onto $SiO_2$ films grown thermally on the silicon wafer using $C_2H_2$ and $H_2$ gases. The Fe catalysts on silicon oxide film were made by RF magnetron sputtering. The grounded grid mesh cover on the substrate holder was used for depositing CNT thin films with high purity. The surface morphologies and chemical structure of deposited CNT films were characterized using SEM, Raman, XPS and TEM. It was observed that deposited CNTs films were carbon fiber type having Bamboo-like multiwall structure and CNT film grown at $600^{\circ}C$ was more dense than that at $550^{\circ}C$, but become less dense at $650^{\circ}C$.

• Journal of Biomedical Engineering Research
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• v.29 no.1
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• pp.52-58
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• 2008

The object of this study is to investigate the effects of intermittent cyclic stretching on the smooth muscle cells (SMCs) seeded onto aligned multi-layered fibrous scaffold. To make multi-layered fibrous scaffold, polyurethane (PU) and poly(ethylene oxide) (PEO) were electrospun alternatively, then were immersed into distilled water to extract PEO. Various types of scaffolds were fabricated depending on fiber directions, i.e., aligned or randomly oriented. The direction of stretching was either parallel or vertical to the fiber direction for the aligned scaffolds. The stretching was also applied to the randomly aligned scaffolds. The duration of stretching was 2 min with 15 min resting period. During the stretching, the maximum and minimum strain was adjusted to be 10 and 7%, respectively with the frequency of 1 Hz. The bioactivities of cells on the scaffolds were assessed by quantifying DNA, collagen, and glycosaminoglycan (GAG) levels. And the cell morphology was observed by staining F-actin. SMCs under parallel stretching to the fiber direction responded more positively than those in other conditions. From the results, we could explain the morphological effect of a substrate on cellular activities. In addition the synergistic effects of substrate and mechanical stimuli effects were confirmed.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.28 no.2
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• pp.81-87
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• 2022

Paper is a promising alternative to petroleum-based plastic materials for sustainable packaging applications. However, paper exhibits poor gas and water vapor barrier properties, which restrict its effective application in the packaging industry. To enhance the properties of papers, sodium caseinate (CasNa)/transglutaminase (TG) coating solutions with various TG contents were prepared and coated on the papers. The chemical and morphological structures, mechanical properties, seal strength, and water vapor barrier properties of the coated papers were thoroughly investigated. The paper properties depended significantly on the chemical and morphological structures. Pristine CasNa and CasNa/TG coating solutions were evenly coated on the paper surfaces, without any cracks. The chemical structure of the CasNa/TG coated papers was slightly influenced by TG addition, resulting in increased elongation at break and enhanced water barrier properties. To promote the use of CasNa-coated papers in packaging applications, additional investigations must be performed to prevent gas and moisture permeation and enhance the mechanical strength of these papers via chemical reactions and introduction of organic/inorganic composites.