• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.4
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• pp.743-747
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• 2007

There has been steady effect for the development of the electron-beam lithography technologies for the circuit patterning of the future semiconductor devices. In this study, we have performed a Monte-Carlo simulation whore $1{\times}10^4$ electrons with various kinetic energies (100eV, 300eV, 500eV, 700eV, and 1000eV) were shot into polymethyl methacrylate(PMMA) resist of 100-nm thickness. The penetration depth of each electron beam in the resist layer were analyzed using Gaussian analysis method.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.1
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• pp.19-23
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• 2019

The PMMA (polymethyl methacrylate)/clay nanocomposites were synthesized by in situ radical polymerizations with different clay contents (3 and 7 wt%) using microwave heating. The nanostructure, optical, and thermal properties of the synthesized PMMA/clay nanocomposites were measured by XRD, TEM, AFM, UV-vis, and TGA. It was found that the intercalated- or exfoliated structure of PMMA/clay nanocomposites was strongly dependent on the content of clay. Thus, the imposition of microwave-assisted polymerization facilitated a delamination process of layered silicates to achieve exfoliation state of interlayer distance. The PMMA/3 wt% C10A nanocomposite with well-dispersed and exfoliated clay nano-layers showed the good optical transparency similar to pure PMMA in this study. The thermal decomposition rates of the PMMA/clay nanocomposites become to be lower compared to that of the pure PMMA, indicating the intercalated- or exfoliated inorganic silicate has high thermal stability. A possible reason is that the thermally segmental motion of PMMA polymer into inorganic silicate interlayer spacing has increased the thermal stability of the PMMA/clay nanocomposites.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.2093-2095
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• 2004

본 논문은 압전소자를 구동장치로 사용한 마이크로 펌프의 제작과 실험에 관한 논문이다. 마이크로 펌프의 상부기판은 polydimethyl siloxane(PDMS)을 소재로 미세유로에 상시 닫힌 밸브가 일체화된 구조로 제작되었고, 하부기판은 polymethyl methacrylate(PMMA)를 소재로 3개의 압전 디스크가 구동기로 부착되었다. 최종적으로 상, 하부 기판은 액상 PUMS로 접합하여 제작했다. 구동기의 입력신호는 6상으로 구형파를 인가하여 연동구동하며 주파수와 전압을 가변하면서 유량을 측정하였다. 구동 주파수가 0.167 Hz이고 전압이 20 V일 때, 마이크로펌프의 1회 토출량은 104 nl이고, 유량은 1.04${\mu}{\el}$/min이다.

• Laser Solutions
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• v.6 no.1
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• pp.33-40
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• 2003

The ablative decomposition mechanism of PMMA(polymethyl methacrylate) and PET(polyethylene terephthalate) with KrF excimer laser(λ : 248nm, pulse duration: 5㎱) is investigated. The UV/Vis spectrometer analysis showed that PMMA is a weak absorber and PET is a strong absorber at the wavelength of 248nm. The results(surface debris, melt, etch depth, etching shape) from drilling and direct writing experiments imply that ablation mechanism of PMMA is dominated by photothermal process, while that of PET is dominated by photochemical process.

• The Journal of Advanced Prosthodontics
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• v.2 no.3
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• pp.65-70
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• 2010

Large oro-facial defects result from cancer treatment consequences in serious functional as well as cosmetic deformities. Acceptable cosmetic results usually can be obtained with a facial prosthesis. However, retention of a large facial prosthesis can be challenging because of its size and weight. This article describes prosthetic rehabilitation of a 57-year-old man having a right lateral mid-facial defect with intraoral-extraoral combination prosthesis. A modified technique to fabricate a hollow substructure in heat-polymerizing polymethyl-methacrylate to support silicone facial prosthesis was illustrated. The resultant facial prosthesis was structurally durable and light in weight facilitating the retention with magnets satisfactorily. This technique is advantageous as there is no need to fabricate the whole prosthesis again in case of damage of the silicone layer because the outer silicone layer can be removed and re-packed on the substructure if the gypsum-mold is preserved.

• Journal of Sensor Science and Technology
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• v.22 no.3
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• pp.227-232
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• 2013

In this research, fiber-optic pressure sensors were fabricated with rugate-structured porous silicon (RPS) diaphragms coated with PMMA (Polymethyl-Methacrylate). The reflectance spectrum of the PMMA/RPS diaphragm was almost the same as that of uncoated RPS diaphragm. However the mechanical strength of the PMMA/RPS diaphragm increased more than that of the uncoated diaphragm. As a result, the fiber-optic sensor fabricated with PMMA/RPS diaphragm could successfully detect more high pressure difference without diaphragm damage than the highest detectable pressure difference of the sensor with normal RPS diaphragm. The response data of the fiber-optic sensor recorded as a function of pressure difference were fitted by theoretical curves. During this process, elastic moduli of the used PMMA/RPS diaphragms were obtained numerically. The dynamic response properties of the fiber-optic sensor were also investigated under continuous variation of the pressure difference conditions.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.61-62
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• 2011

본 논문에서는 top-contact 구조의 유기 박막 트랜지스터를 이용하여 정류기와 인버터를 제작하고 전기적 특성을 분석 하였다. 게이트 절연막으로는 PMMA (polymethyl methacrylate)를 사용하였고 유기물 활성층으로 pentacene을 진공 증착하여 사용하였다. 유기 박막 트랜지스터로 제작된 정류기는 약 3 V의 DC 전압을 얻어 39 %의 효율특성을 보였고, 인버터는 1.2의 이득값을 얻어 유기전자회로의 실용 가능성을 확인 하였다.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.1
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• pp.79-84
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• 2003

A light guide panel is an element of the LCD backlight module that is often used for the display of compact electronic devices. In this study, a laser marking system is proposed to fabricate light guide panel, which can replace other manufacturing methods such as silk printing, stamping, or v-cutting methods. The objective of this research is to evaluate the process parameters of the laser marking system. Light guide patterns were marked with a 50W $CO_2$ laser (CW) to understand the effects of average power and scanning speed on the geometry and quality of groove pattern. The width of the fabricated grooves increases with increasing laser power and decreasing scan speed. In order to analyze surface characteristics and optical properties (luminance, uniformity), SEM photography and BM7 (luminance measuring system) were used. As a result, the optimal conditions of the process parameters were determined.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.332-335
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• 2004

Polymethyl Methacrylate(PMMA) mortars using EPS solution-based binders are prepared with various unsaturated polyester resin(UP) contents of binder, and tested for working life. heat exothorm temperature, length change. compressive strength and temperature dependence of compressive strength. As a result, the working life of PMMA mortar is lengthened with raising UP content of binder. Length change of the mortar was condensed from expansion to shrinkage with increasing UP content, and non shrinkage of the mortar is obtained at about UP content of $2.5\%$. The compressive strength of the mortar is increased with an increase in the UP content and reach maximum at UP content of $5\%$. However thermal resistance improvement of the mortar by increasing UP content was not recognized. UP resin was recommended as an effective agent for shrinkage control and strength development of PMMA mortar.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1068_1069
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• 2009

$TiO_2$의 계면적을 넓힘으로써 태양전지의 특성을 향상시키기 위해 정렬도가 높은 나노 기공 (nanopore, NP) 이산화티타늄 ($TiO_2$)을 이용하여 복합 태양전지를 제작하였다. Polymethyl methacrylate (PMMA)를 사용한 nanoimprinting lithography (NIL) 기술을 이용하여 NP $TiO_2$를 제작하였으며. 광활성층으로는 poly(3-hexylthiophene) (P3HT)와 [6,6]-phenyl $C_{61}$ butyric acid methyl ester (PCBM)을 사용하였다. NP $TiO_2$를 이용한 태양전지의 전력변환효율이 1.49%로 표면이 고른 소자의 효율인 1.18%에 비해 26% 가량 증가하였다. 이와 같은 효율 향상의 원인은 $TiO_2$와 광활성층의 계면이 증가되어 전하의 생성과 분리가 용이해졌기 때문인 것으로 사료된다.