• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.150-150
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• 2016

디스플레이, 센서 등 전자소자는 소형화 단계를 지나 인체 부착형 소자로의 발전을 요구하고 있다. 부착형 소자에서는 접착력과 큰 마찰력이 필요하지만 마찰특성이 더 중요하므로 인체 및 물체의 마찰을 위해서는 다양한 표면에 대항하는 마찰 특성과 내구성이 요구되며 이를 위해 개코도마뱀 또는 딱정벌레, 말벌날개와 같은 자연모사형 건식 마찰 방식에 대한 연구가 활발히 진행되고 있다. 그러나 기존 폴리머를 이용하여 자연모사형 마이크로/나노 구조 형성은 기계적으로 가공된 금형 몰딩을 통한 매무 복잡한 공정을 요구된다. 본 연구에서는 이러한 복잡한 공정을 통한 마찰재 제작을 단순화하기 위해서 플라즈마 표면처리를 활용하여 나노구조 형성하는 방법을 소개하고자 하며, 건식 접착 및 마찰용 폴리머 소재(PDMS(Poly dimethyl siloxane))에 따른 표면구조 변화와 표면에너지 및 화학결합 변화에 대한 연구를 수행하였다. 플라즈마 표면처리를 위해서 자체 개발한 선형이온소스를 활용하였으며 입사에너지에 따라 표면형상 변화를 주사전자현미경을 활용하여 관찰하였다. 표면에너지 변화는 접촉각측정기를 활용하였으며, Tribology tester(Ball on disk)를 활용하여 마찰특성을 평가하였다. PDMS(Poly dimethyl siloxane)는 입사에너지가 증가함에 따라 주름형태 구조 크기가 증가하는 것을 관찰하였고, 플라즈마 처리를 통해 표면에너지 및 마찰력 증가를 관찰하였다. 그리고 플라즈마 처리 후 표면에너지 변화인 FOTS(Trichloro-(1H,1H,2H,2H- perfluorooctyl) silane) 처리를 통하여 표면에너지 감소와 마찰력이 절반으로 감소하였다. 본 연구 결과는 나노구조에 따라 표면형상 및 표면에너지 변화에 따른 PDMS의 마찰력 변화를 확인하였고, 이러한 특성을 활용하여 마찰재와 피부 부착형 접착 패치에 응용이 가능할 것으로 기대된다.

• Composites Research
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• v.23 no.3
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• pp.58-63
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• 2010

Tensile and flexural properties and electrical conductivity of MWCNT/epoxy composites with different aspect ratios of MWCNTs were compared. The MWCNT/epoxy mixtures were prepared by mechanical dispersion methods using a homomixer and a three-roll mill, and then composite samples were fabricated by compression molding process. The fractured surfaces of the samples were observed by SEM in order to evaluate the degree of dispersion of MWCNTs. The addition of MWCNTs into epoxy resin improved its tensile strength by 7.0% while its flexural strength increased slightly as compared with the one without MWCNTs. In the case of MWCNTs having highest aspect ratio, the mechanical properties of the composites were decreased. When the contents of CM-95 MWCNTs were varied, maximum of tensile and flexural strengths occurred at 1wt% and 0.5wt%, respectively. From the higher contents than these, tensile and flexural strengths of the composites decreased. Electrical conductivities of in-plane and thought-the-thickness directions of MWCNT/epoxy composites were measured using a two-point probe method. They increased with the increase of the aspect ratios and concentrations of MWCNTs in the epoxy matrix.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.1 s.178
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• pp.97-104
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• 2006

ELID(Electrolytic In-process Dressing) grinding is an excellent technique for mirror grinding of various advanced metallic or nonmetallic materials. A polishing process is also required for elimination of scratches present on ELID grinded surfaces. MAP(Magnetic Assisted Polishing) has been used as polishing method due to its high polishing efficiency and to its resulting in a superior surface quality. This study is describing an effective fabrication method combining ELID and MAP of nano-precision mirror grinding for glass-lens molding mould. It also presents some techniques for achieving the nanometer roughness of the hard metals, such as WC-Co, which are extensively used in precision tooling material.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.04a
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• pp.55-56
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• 2009

A light guiding plate (LGP) with nanometer-sized patterns was fabricated by injection molding method which employed electrically healed mold and the transcription of injection-molded parts was investigated. A Ni stamper was fabricated using MEMS technology. The Ni stamper was then installed in a movable heated core which is a key part of the mold. Using this mold, injection-molded plastic LGP parts were manufactured at different mold temperatures and the effect of the temperature on the transcription of the parts was investigated.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.632-635
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• 2003

As a process technology of nano pattern with a new conception for economic and practical technology of alternative nano process. process technologies such as Embossing, Imprinting. Molding and Inking are beginning to make its appearance. Among these alternative processes, nano mold process is a process that is of benefit to mass production and keeps excellency of reproduction and high quality of parts. In this study, we experienced micro precision machining technology of nano stamper for the injection mold of optical disk with big capacity. Especially, Flatness and uniformity are important for nano stamper with global area, for the purpose of developing polishing technology of micro precision of Back polishing only being used for nano stamper, we carried out a basic study to secure flatness standards

• Transactions of Materials Processing
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• v.16 no.1 s.91
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• pp.9-14
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• 2007

In this paper, a mold temperature control method for injection molding is proposed. The inner surface of mold is locally heated by jet impingement to improve pattern transcription. Heating by hot jet is completed while the mold is open. An experimental system that realizes the proposed idea has been built, which includes mold, nozzle assembly and heater. Actual injection molding process including the proposed heating procedure has been conducted to verify the validity of the method. The process has been done for several conditions with different jet temperatures and duration of heating. The results from different conditions are compared.

• Transactions of Materials Processing
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• v.17 no.5
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• pp.337-342
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• 2008

The injection molding process has high accuracy and good reproducibility that are essential for mass production at low cost. Conventional molding processes typically use the water-based mold heating and air cooling methods. However, in the nano injection molding processes, this semi-active mold temperature control results in the several defects such as air-flow mark, non-fill, sticking and tearing, etc. In order to actively control temperature of the molds and effectively improve the quality of the molded products, the novel nano injection molding system, which uses active heating and cooling method, has been introduced. By using the Peltier devices, the temperature of locally adiabatic molds can be controlled dramatically and the quality of the molded patterns can be improved.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.240-243
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• 2009

Recently, many researches on the development of super-hydrophobic and anti-reflective surfaces have been concentrated on the fabrication of nano-patterned products. The nano-patterned mold is a key to replicate nano-patterned products by mass production techniques such as injection molding and UV molding. The present paper proposes fabricating nano-patterned mold with cost-effective method. The nano-pattern molded was fabricated by electroforming the anodic aluminum oxide template without E-beam lithography. The final mold with nano-patterns showed the pores with the diameter of $100{\sim}120$ nm and the height of 150 nm was fabricated.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.1259-1261
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• 2003

고정밀 와이어컷 방전가공기는 높은 정밀도를 갖는 금형제작에 사용되고 있는 공작기계로서 최근 나노단위의 가공기술이 요구되는 산업추세에 발맞추어 고속, 고정밀 가공특성을 갖추도록 전반적인 성능개선이 이루어지고 있다. 본 논문에서는 기존 Thyristor를 이용한 위상제어 방식보다 우수한 특성을 갖는 스위칭모드 방식의 10kW급 직류 전원장치의 개발에 대해 기술하고있다.

• Transactions of Materials Processing
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• v.19 no.2
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• pp.73-78
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• 2010

Recently, many researches on the development of super-hydrophobic surface have been concentrated on the fabrication of nano-patterned products. Nano-patterned mold is a key to replicate nano-patterned products by mass production process such as injection molding and UV molding. The present paper proposes the new fabricating method of nano-patterned mold at low cost. The nano-patterned mold was fabricated by electroforming the anodic aluminum oxide membrane filled with UV curable resin in nano-hole by capillary phenomenon. As a result, the final mold with nano-patterns which have the holes with the diameter of 100~200 nm was fabricated. Furthermore, the UV-molded products with clear nano- patterns which have the pillars with the diameter of 100~200nm were achieved.