• 전기의세계
• /
• v.26 no.2
• /
• pp.57-65
• /
• 1977

In roder to investigate the influence of treeing on electric breakdown of solid organic insulator the initiation and growing mechanism of tree itself, and the correlation between corona discharge and treeing phenomena in solid orgainc insulating materials, several experiments were carried out by means of needle test on polymethyl-methacrylate. The obtained results showed that the existence of voids in specimen had important effects on initiation voltage of trees and, when the direct voltage was applied, the initiation voltage of trees increased by space charge effect. And also the stagnation phenomena due to the transfer of vacancy cluster or polymekr cage in specimen might beconsidered in process of growth of trees, and corona discharge seemed to be the pre-phenomena of treeing because trees were normally initiated by internal discharge in voids.

• Journal of the Korean Ceramic Society
• /
• v.54 no.2
• /
• pp.102-107
• /
• 2017

The dependence of the IR optical properties of PMMA/$Al_2O_3$ nanocomposite on the alumina content was investigated in the wavelength range of $3500-2800cm^{-1}$. The samples were prepared via emulsion polymerization technique using oleic acid as a coupling agent. Grafting density calculations were carried out by means of elemental analysis CHN to yield the best coupling agent content. FTIR analysis confirmed the existence of a chemical bond between aluminum oxide and oleic acid. The outcomes of XRD analyses showed the presence of cubic gamma aluminum oxide in the nanocomposite, in contrast to the amorphous nature of PMMA. TEM images showed the core-shell morphology of the particles other than pristine PMMA. Optical constants of the nanocomposite were calculated based on FTIR spectra and the Kramers-Kronig equations. The presence of nano alumina modified some of the optical indexes in IR region.

• Proceedings of the IEEK Conference
• /
• 2006.06a
• /
• pp.555-556
• /
• 2006

In this paper, we have proposed a novel process using two-step electron beam lithography to fabricate 20 nm T-gates for high performance MODFETs. Two-step lithography reduces electron forward scattering by defining the foot on a thin (100 nm) bottom-layer of polymethyl methacrylate (PMMA) at the second step, the T-gate head having been developed at the first step. Adopting a low temperature development technique for the second step reduces the detrimental effect of head exposure on foot definition. We have shown that 20 nm T-gate can be patterned with this process.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.11 no.10
• /
• pp.768-772
• /
• 1998

The new type polymer electrolyte composed of polymethyl methacrylate(PMMA) - polyethy leneoxide(PEO) contain $LiClO_4$ -EC/PC was developed for the weightless and long or life time of lithium polymer batery system with using polyaniline electrode. the gel type electrolytes were prepared by PMMA with PEO at different lithium salts in the glove box. The minimum thickness of PMMA-PEO gel electrolyte for the slim type is about(400~450$\mu\textrm{m}$. These gel electrolyte showed good compatibility with lithium electrode. The test cell Li/polymer electrolyte/polyaniline solid state cell which was prepared by different lithium salt was researched by electrochemical technique.

• Journal of the Optical Society of Korea
• /
• v.9 no.3
• /
• pp.103-106
• /
• 2005

Recently, polymethyl methacrylate based plastic optical fibers (POFs) have attracted considerable attention as a potential medium for local area network (LAN) and home network applications. Since the POFs have very low optical loss at around 650mm, in particular, it becomes quite important to develop GHz transmitters operating at this wavelength for high bit rate optical transmission applications of the POFs. In this paper, we present generation of ${\geq}1.5 Gbps$ pseudo-random binary sequence optical signals by using a gain switched InGaA1P Fabry-Perot semiconductor laser with a high frequency filter, operating at 650mm, and the application of these signals to bandwidth measurement of POFs.

• Journal of the Semiconductor & Display Technology
• /
• v.12 no.3
• /
• pp.35-39
• /
• 2013

In this paper, we developed an optical sheet for LED lighting with integrated $CO_2$ gas and temperature sensor which can monitor at the indoor environment. The optical sheet for LED lighting is fabricated through PMMA(Polymethyl methacrylate) injection process using mold. This research enables to fabricate the reflective sheet, light-guide plate and the prism sheet in a optical sheet. The fabricated sheet demonstrates higher intensity of optical efficiency compared with single-sided sheets. The $CO_2$ sensor was fabricated using NDIR(NON-Dispersive Infrared) method and it has $0.0235mV/V{\cdot}PPM$ sensitivity. The temperature sensor was fabricated using RTD(Resistance temperature detector) method and it has $0.563{\Omega}/^{\circ}C $sensitivity.

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09a
• /
• pp.475-476
• /
• 2006

Using microwave synthesized HAp nano powder and polymethyl methacrylate (PMMA) as a pore-forming agent, the porous biphasic calcium phosphate (BCP) ceramics were fabricated depending on the sintering temperature. The synthesized HAp powders was about 70-90 nm in diameter. In the porous sintered bodies, the pores having $150-180\;{\mu}m$ were homogeneously dispersed in the BCP matrix. Some amounts of pores interconnected due the necking of PMMA powders which will increase the osteoconductivity and ingrowth of bone-tissues while using as a bone substrate. As the sintering temperature increased, the relative density increased and showed the maximum value of 79.6%. From the SBF experiment, the maximum resorption of $Ca^{2+}$ ion was observed in the sample sintered at $1000^{\circ}C$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2005.07a
• /
• pp.349-349
• /
• 2005

수동소자를 PCB(Printed Circuit Board) 안으로 집적하기 위한 방법의 일환으로 polymer-metal, polymer-ceramic composite에 연구가 국내외 연구 국내외 연구기관에서 광범위하게 진행되고 있다. 본 연구에서는 polymer-metal-ceramic composite 에서 PZT-coated Ni의 volume fraction에 따른 유전율 변화에 대하여 조사하였다. 원료로는 PZT(52/48) solution. 니켈금속분말, PMMA(polymethyl methacrylate)를 사용하였다. 전기적 특성은 임피던스분석기를 이용하여 측정하였으며 mixing rule과 percolation theory를 이용하여 결과를 해석하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2006.06a
• /
• pp.343-343
• /
• 2006

집적회로기판의 소형화 추세에 따라 커패시터, 인덕터, 저항과 같은 수동소자를 PCB 기판내부에 임베딩하는 연구가 국내외에서 활발하게 진행되고 있다. 본 논문에서는 polymer-metal-ceramic의 3상 복합체 구조를 가지는 임베디드 커패시터에서 Bimodal PZT분말에 따른 유전 특성에 대하여 고찰하였다. 매트릭스를 형성하는 고분자 재료로는 PMMA(polymethyl methacrylate)를 사용하였으며, 충분히 혼합된 분말을 고온에서 프레싱하여 시편을 제조하였다. 유전특성은 임피던스분석기 및 LCZ 미터를 이용하여 측정하였으며, 실험결과는 혼합법칙과 Percolation 이론을 이용하여 해석하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2007.11a
• /
• pp.63-64
• /
• 2007

Polystyrene-block-polymethyl methacrylate (PS-b-PMMA) can pattern nanoscale structures over large areas. However these patterns have a short-range order. These short-range order limits their utility in some applications. Consequently, we have to overcome this limitation of block-copolymer. In this study we added a electrical field to the standard block-copolymer patterning method for long-range ordered arrays of nanostructures. This method is conformed by annealing a block copolymer with applied voltages. It is very simple method that do not have any additional hour. In this reason it can be applied easily for other nanostructure fabrications. This method opens up a new route to the controlled phase separation of block copolymers with precise place of the nanostructures.