• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.269-270
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• 2011

• Design & Manufacturing
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• 제16권3호
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• pp.9-15
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• 2022

In order to reduce the manufacturing costs of the glass lens, it is necessary to manufacture a lens using a UV curable resin or a thermosetting resin, which is a curable material, in order to replace a glass lens. In the case of forming a lens using a thermosetting material, it is necessary to form several lenses at once using the wafer-level lens manufacturing technologies due to the long curing time of the material. When a lens is manufactured using a curable material, an error in the shape of the lens due to the shrinkage of the material during the curing process is an important cause of defects. The major factors for these shape errors and deformations are the shrinkage and the change of mechanical properties in the process of changing from a liquid material during curing to a solid state after complete curing. Therefore, it is necessary to understand the curing process of the material and to examine the shrinkage rate and change of physical properties according to the degree cure. In addition, it is necessary to proceed with CAE for lens molding using these and to review problems in lens manufacturing in advance. In this study, the viscoelastic properties of the material were measured during the curing process using a rheometer. Using the results, Rheological investigation of cure kinetics was performed. At the same time, The shrinkage of the material was measured and simple mathematical models were created. And using the results, the molding process of a single lens was analyzed using Comsol, a commercial S/W. In addition, the experiment was conducted to compare and verify the CAE results. As a result, it was confirmed that the shrinkage rate of the material had a great influence on the shape precision of the final product.

• 한국세라믹학회지
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• 제34권11호
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• pp.1151-1158
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• 1997

Fracture of uni-directional carbon fiber reinforced carbon matrix composite is strongly dependent on the orientation of basal plane in graphite matrix when it is limited within matrix. The orientation of basal planes are vertically stacked to carbon fiber which results in the weakness for applied tensile or shear force in thermosetting resin derived-carbon matrix composite. Microtextural control of the matrix was tried through chemical interaction between metal carbides and furan resin derived-carbon matrix. SiC and TiO2 addition made the orientation disordered. However, porosity increased due to decomposition of SiC. Interfacial bonding could be controlled by TiO2 addition, but carbon fiber was considerably reacted with TiC during thermal treatment higher than 2$600^{\circ}C$. Therefore, it is desirable to control the thermal treatment temperature at which decomposition of SiC was not serious and TiC/C was not formed eutectoid.

• 한국기계가공학회지
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• 제16권5호
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• pp.25-30
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• 2017

Carbon-fiber-reinforced plastic (CFRP) composite materials have been widely used in various industrial fields because the design variables can be adjusted according to the application of the required structure. Thermosetting and thermoplastic resins are used as the base materials of CFRP composites for the lightweight construction of automotive components. Thermoplastics have several advantages such as no curing and recyclability compared to thermosetting resin. In this study, CFRP composites were made using the Long-Fiber Thermoplastic-Direct (LFT-D) process. The LFT-D process includes an in-line production system that directly impregnates a thermoplastic resin, extrudes the composite material, and molds it. This process increases the strength and decreases the molding time. The tensile strength characteristics on the mechanical properties of CFRP were analyzed according to the parameters of LFT-D based on thermoplastics. To analyze the properties of CFRP, the specimens were prepared based on the tensile test standard ASTM 3039 of composite materials.

• 한국기계가공학회지
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• 제16권6호
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• pp.133-138
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• 2017

Recently, CFRP composites are widely used as lightweight materials have with excellent mechanical properties and can beare widely used in various fields. In general, thermosetting resins are used for CFRP. However, in recent years, studies have been carried out using thermoplastic resins have been actively carried out to overcome the disadvantages of thermosetting resins. The LFT-D system is a molding method in which a fiber is directly cut to a the desired length while being impregnated with a thermoplastic resin to produce a compound and that is then press-molding molded to form the product. In this paper, before the production of the trailing arm, the compression molding analysis was carried out in order to grasp the problems that may occur during production. Through cCompression molding analysis was applied to calculate of the minimum press pressure and to compare and analysis analyze the molding conditions characteristic required to formfor forming the trailing arm.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.380-380
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• 2013

본 논문에서는 외기 환경 요인 중에서 H2O와 O2의 영향으로 성능이 저하되는 유기박막트랜지스터(OTFT)의 수명시간 향상을 위하여 필요한 passivation layer의 효과에 대하여 알아 보았다. OTFT에 기존의 액상 공정이나 증착 공정으로 단일 passivation layer또는 다층 passivation layer를 형성하는 방식과는 다르게 향후에 산업 전반에 적용이 기대되는 것을 고려하여 제작 공정의 간편성을 위하여 film 형태로 되어 있는 열경화성 epoxy resin film으로 passivation layer를 구현하는 방법을 사용하여 OTFT의 storage stability를 평가하였다. passivation layer가 없는 OTFT와 열경화성 epoxy resin film으로 passivation된 OTFT의 전기적 특성이 서로 비교 평가되었으며 또한 30일 동안 온도 $25^{\circ}C$ 상대습도 40%의 환경을 갖는 Desicator 안에서 소자를 보관하여 시간에 따른 전기적 특성 변화를 검증하여 epoxy resin film의 passivation layer으로의 적용가능성을 검증하였다. 결과적으로 30일 후의 passivation layer가 없는 OTFT의 전기적 특성은 매우 낮게 떨어진 반면에 epoxy resin film으로 passivation layer가 구현된 OTFT의 mobility는 $0.060cm^2$/Vs, VT는 -0.18 V, on/off ratio는 $3.7{\times}10^3$으로 초기의 소자 특성이 잘 유지되는 결과를 얻었다. OTFT는 Flexible한 polyethersulfone (PES)기판에 게이트 전극이 하부에 있는 Bottom gate 구조로 제작되었고 채널 형성을 위한 유기반도체 재료로 6,13-bis (triisopropylsilylethynyl) (TIPS) pentacene이 사용되었고 spin coating된 Poly-4-vinylphenol (PVP)가 게이트 절연체로 사용되었다. 이때 Au전극은 Shadow mask를 이용하여 증착하였다. 또한 OTFT의 채널 길이 $100{\mu}m$, 채널 폭 $300{\mu}m$의 영역에 Drop casting법을 사용하여 채널을 형성하였다. 물리적 특성은 scanning electron microscopy (SEM), scanning probe microscopy (SPM), x-ray diffraction (XRD)를 사용하여 분석하였고, 전기적 특성은 Keithley-4200을 사용하여 추출하였다.