• 유변학
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• 제11권1호
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• pp.34-43
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• 1999

수지 이동 성형공정에서 섬유직조가 수지에 의해 함침될 때 발생하는 기공 또는 나쁜 젖음성은 최종 성형품의 물성 저하에 심각한 영향을 미치게 된다. 본 연구에서는 수지이동 성형공정에서의 이러한 문제점을 극복하기 위한 기초 데이터를 제공하기 위하여, 실란 커플링제를 사용한 섬유의 표면 개질이 수지의 유동특성과 수지와 섬유 사이의 젖음성 및 기공함량에 미치는 영향을 조사하였다. 빔 형태의 금형을 대상으로 에폭시 수지와 평직형태의 유리섬유를 사용하여 미시적인 유동가시화 실험 및 경화실험을 수행하였다. 섬유의 표면을 개질함으로써 수지와 섬유 사이의 동적 접촉각이 감소하고 위킹속도는 증가한 것으로 나타났으며, 이러한 결과로부터 본 연구에서 사용한 화학적 표면개질이 섬유직조의 젖음성 및 미시적 흐름 거동을 향상시킬 수 있는 중요한 요인임을 확인할 수 있었다. 또한 수지의 높은 온도와 낮은 침투 속도는 동적 접촉각을 감소시키기 위한 중요한 가공 변수임을 알 수 있었다. 그러나 섬유직조의 투과성은 표면을 개질하였을 경우 오히려 감소하였는데, 이는 젖음성의 향상으로 인하여 수지와 섬유 사이의 접촉시간의 증가에 기인하는 것으로 생각된다. 마지막으로 경화공정을 통해 제조된 시편의 기공 함량을 측정 비교한 결과, 표면개질은 수지이동 성형공정에서의 기공형성에도 중요한 변수로 작용하여, 수지와 섬유 사이의 젖음성을 향상시키고, 최종 성형품의 기공함량을 감소시킴을 확인할 수 있었다.

• Macromolecular Research
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• 제15권4호
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• pp.348-356
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• 2007

The aim of this study was to fabricate a submicro-and micro-patterned fibronectin coated wafer for a cell culture, which allows the positions and dimensions of the attached cells to be controlled. A replica molding was made into silicon via a photomask in quartz, using E-beam lithography, and then fabricated a polydimethylsiloxane stamp using the designed silicon mold. Hexadecanethiol $[HS(CH_2){_{15}}CH_3]$, adsorbed on the raised plateau of the surface of polydimethylsiloxane stamp, was contact-printed to form self-assembled monolayers (SAMs) of hexadecanethiolate on the surface of an Au-coated glass wafer. In order to form another SAM for control of the surface wafer properties, a hydrophilic hexa (ethylene glycol) terminated alkanethiol $[HS(CH_2){_{11}}(OCH_2CH_2){_6}OH]$ was also synthesized. The structural changes were confirmed using UV and $^1H-NMR$ spectroscopies. A SAM terminated in the hexa(ethylene glycol) groups was subsequently formed on the bare gold remaining on the surface of the Aucoated glass wafer. In order to aid the attachment of cells, fibronectin was adsorbed onto the resulting wafer, with the pattern formed on the gold-coated wafer confirmed using immunofluorescence staining against fibronectin. Fibronectin was adsorbed only onto the SAMs terminated in the methyl groups of the substrate. The hexa (ethylene glycol)-terminated regions resisted the adsorption of protein. Human dermal fibroblasts (P=4), obtained from newborn foreskin, only attached to the fibronectin-coated, methyl-terminated hydrophobic regions of the patterned SAMs. N-HDFs were more actively adhered, and spread in a pattern spacing below $14{\mu}m$, rather than above $17{\mu}m$, could easily migrate on the substrate containing spacing of $10{\mu}m$ or less between the strip lines.

• Composites Research
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• 제31권6호
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• pp.379-384
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• 2018

본 연구에서는 동일한 표면 형태를 가지는 탄소섬유에 다양한 사이징제를 처리함에 따라 발생하는 에폭 시 수지의 유동 특성 변화를 분석하였다. 동적 접촉각(DCA) 측정을 통해 단일 탄소섬유의 젖음성(Wettability)을 측정하였다. DCA 측정 결과와 함침 특성 간의 연관성을 살피기 위해 Wicking test와 VARTM test를 수행하였다. 추가적으로, 탄소섬유의 표면 에너지 등 다양한 표면 특성을 분석하였으며 Micro-droplet test를 통해 수지와 탄소섬유계면의 계면전단강도를 측정하였다. 이러한 실험 결과를 기반으로, 함침 속도의 증대를 위해서는 탄소섬유의 사이징제가 적정 수준의 표면 에너지를 가져야 하며, 사이징제의 화학적 조성을 조정하여 에폭시 수지의 유동 특성과 계면전단강도가 모두 개선 가능함을 확인하였다.

• Design & Manufacturing
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• 제2권5호
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• pp.1-4
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• 2008

LCD-BLU (Liquid Crystal Display - Back Light Unit) is one of kernel parts of LCD unit and it consists of several optical sheets(such as prism, diffuser and protector sheets), LCP (Light Guide Plate), light source (CCFL or LED) and mold frame. The LGP of LCD-BLU is usually manufactured by forming numerous dots with $50-200{\mu}m$ in diameter on it by erosion method. But the surface of the erosion dots of LGP is very rough due to the characteristics of the erosion process during the mold fabrication, so that its light loss is high along with the dispersion of light into the surface. Accordingly, there is a limit in raising the luminance of LCD-BLU. Especially, the negative and positive micro-lens pattern fabricated by modified LiGA with thermal reflow process was applied to the optical design of LGP.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2005년도 생물공학의 동향(XVI)
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• pp.19-19
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• 2005

This paper reports a novel magnetic force-based microfluidic immunoassay using microbeads and magnetic nanoparticles. The magnetic force-based immunoassay was devised first and successfully applied to detect the rabbit IgG as the model analyte of microfluidic sandwich immunoassay. The microchannels were fabricated by poly(dimethysiloxane) (PDMS) molding processes and bonded on a slide glass by plasma treatment. At the part of the inlet, sample solution was hydrodynamically focused. The focused microbeads of sample solution were flowed through the 150 ${\mu}m$ width channel of outlet. However, when the microbeads are conjugated with the superparamagnetic nanoparticles under the applied magnetic fields, they will switch their flow path and flow through the 95 ${\mu}m$ width channel of outlet. The movements of microbeads conjugated with magnetic nanoparticles were demonstrated by magnetic field $gradients.^{1)}$ High magnetic field gradients using micro electromagnets could be applied to this detection method for high sensitivity and lower detection limit. In addition, the multiplexed $immunoassay^{2)}$ using an encoded microbead which is immobilized with a certain antibody could be possible using this detection principle.

• 한국가시화정보학회지
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• 제5권1호
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• pp.3-8
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• 2007

We present simple methods for fabricating high aspect-ratio polymer nanostructures on a solid substrate by rigiflex lithography with tailored capillarity and adhesive force. In the first method, a thin, thermoplastic polymer film was prepared by spin coating on a substrate and the temperature was raised above the polymer's glass transition temperature ($T_g$) while in conformal contact with a poly(urethane acrylate) (PUA) mold having nano-cavities. Consequently, capillarity forces the polymer film to rise into the void space of the mold, resulting in nanostructures with an aspect ratio of ${\sim}4$. In the second method, very high aspect-ratio (>20) nanohairs were fabricated by elongating the pre-formed nanostructures upon removal of the mold with the aid of tailored capillarity and adhesive force at the mold/polymer interface. Finally, these two methods were further used to fabricate micro/nano hierarchical structures by sequential application of the molding process for mimicking nature's functional surfaces such as a lotus leaf and gecko foot hairs.

• 소성∙가공
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• 제16권1호
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• pp.42-47
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• 2007

LCD-BLU is one of kernel parts of LCD and it consists of several optical sheets: LGP, light source and mold frame. The LGP of LCD-BLU is usually manufactured by etching process and forming numerous dots with $50\sim300{\mu}m$ diameter on the surface. But the surface of the etched dots of LGP is very rough due to the characteristics of the etching process during the mold fabrication, so that its light loss is high along with the dispersion of light into the surface. Accordingly, there is a limit in raising the luminance of LCD-BLU. In order to overcome the limit of current etched dot patterned LGP, optical pattern with continuous microlens was designed using optical simulation CAE. Also, a mold with continuous micro-lens was fabricated by UV-LiGA reflow process and applied to 7 inch size of navigator LCD-BLU in the present study.

• 소성∙가공
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• 제16권1호
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• pp.48-53
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• 2007

LCD-BLU(Liquid Crystal Display - Back Light Unit) consists of several optical sheets: LGP(Light Guiding Plate), light source and mold frame. The LGP of LCD-BLU is usually manufactured by etching process and forming numerous dots with $50{\mu}m$ in diameter on the surface. But the surface roughness of LGP with etched dots is very high, so there is much loss of light. In order to overcome the limit of current etched dot patterned LGP, optical pattern design with microlens of $50{\mu}m$ diameter was applied in the present study. The microlens pattern fabricated by modified LiGA with thermal reflow process was applied to the optical design of LGP and optical simulation was carried out to know tendency of microlens patterned LGP simultaneously. The attention was paid to the effects of different aspect ratio(i.e. $0.2\sim0.5$) of optical pattern conditions to the brightness distribution of BLU with microlens patterned LGP. Finally, high aspect ratio microlens patterned LGP showed superior results to the one made by low aspect ratio in average luminance.

• 한국전기전자재료학회논문지
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• 제21권3호
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• pp.203-207
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• 2008

Chemical mechanical polishing (CMP) allows the planarization of wafers with two or more materials. There are many elements such as slurry, polishing pad, process parameters and conditioning in CMP process. Especially, polishing pad is considered as one of the most important consumables because this affects its performances such as WIWNU(within wafer non-uniformity) and MRR(material removal rate). In polishing pad, grooves and pores on its surface affect distribution of slurry, flow and profile of MRR on wafer. A subject of this investigation is to apply CMP for planarization of shallow trench isolation structure using microstructure(MS) pad. MS pad is designed to have uniform structure on its surface and manufactured by micro-molding technology. And then STI CMP performances such as pattern selectivity, erosion and comer rounding are evaluated.

• Design & Manufacturing
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• 제2권2호
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• pp.25-28
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• 2008

Micro fabrication of biochip such like lab-on-a-chip becomes increasingly important. In this study, we designed and manufactured of new molds which were main factors for forming process in order to mass produce of biochip using forming process. Forming analysis of biochip was performed by Moldflow software. Results of this study are able to design and manufacture the mold which can be easy to eject the workpiece by using the slide mechanism for biochip.