• Membrane Journal
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• v.18 no.3
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• pp.226-233
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• 2008

PTMSP/PMMH dendrimer composite membranes were made by dispersing $0{\sim}20$ wt% (based on polymer content) PMMH dendrimer nanoparticles in the PTMSP casting solution. The effect of PMMH dendrimer on gas permeability characteristics of the composite membranes was investigated. The permeabilities of $H_2,\;N_2,\;CO_2$, and $CH_4$ decreased as the PMMH dendrimer content within PTMSP increased. The permeabilities of different gases except hydrogen in PTMSP/PMMH dendrimer membranes follow the order: $N_2\;<\;CH_4\;<\;CO_2$ which are consistent with the order of critical temperature ($N_2\;<\;CH_4\;<\;CO_2$). The selectivities of gases for $N_2$ increased as the PMMH dendrimer content within PTMSP increased. The $CO_2/N_2$ selectivity increased from 5.6 up to 16.9.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11b
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• pp.170-173
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• 2005

The objective of this paper is to perform measurements of power transmission and reflection coefficients in a coupled plate. The coupled plate has been divided into 2 subsystems. The out-of-plane vibration has been only considered with assumption of relatively small in-plane vibration. The coupling loss factors have been measured with consideration of the power balance condition. The power transmission and reflection coefficients has been estimated from the measured values of the coupling loss factors. The measured power transmission and reflection coefficients have been compared with the corresponding theoretical coefficients in a semi-infinite coupled plate.

• Journal of Power System Engineering
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• v.12 no.5
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• pp.54-58
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• 2008

최근 열교환기의 향상을 위해 발포다공성매체의 적용이 증가하고 있다. 열교환기의 적용에 있어서 발포다공성매체의 이점을 살펴보기 위해 본 연구에서는 2가지 실험을 수행하였다. 첫 번째는 수력의 관점에서 투과계수 및 내부계수를 결정하는 것이고, 두 번째는 열교환의 관점에서 다공성매체의 유효전도율을 측정하는 것이다. 본 실험에서는 기공도는 거의 같으나 기공의 크기가 각각 20 ppi와 40 ppi인 구리 다공성매체를 사용하였다. 실험의 결과는 40 ppi 크기의 다공성매체가 수력과 열교환, 두가지 관점 모두에서 보다 높은 저항 효율을 나타낸다는 것을 보여준다.

• Journal of the Korean Vacuum Society
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• v.17 no.2
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• pp.138-147
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• 2008

$SiO_2/TiO_2/ZrO_2$ broadband anti-reflective multi-layer thin films were prepared at room temperature by RF sputtering system. Optical constants and structural properties on each layer of films were analyzed by spectroscopic ellipsometer and transmittance spectra of the films were measured by $UV-V_{is}$ spectrophotometer in the range of 300$\sim$900 nm. To evaluate the films, we compared the measured and analyzed spectra with designed spectra. We investigated influence of discrepancy of thickness and refractive indices of each layer on changes of the transmittance spectra. It was found that refractive indices and shape of dispersion of deposition materials are more contributed to changes of the transmittance spectra than thickness of layer.

• Korean Journal of Materials Research
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• v.7 no.5
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• pp.417-422
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• 1997

본 연구에서는 LPCVD, PECVD, ECR plasma CVD방법을 이용하여 x선 노광 공정용 마스크의 투과막재료로써의 실리콘질화막의 증착과 그의 물성에 관하여 실험하였다. X선 노광 마스크용 투과막의 재질로써 요구되는 적정인장응력에 가지는 증착조건으로 실리콘질화막을 1$\mu\textrm{m}$정도의 두께로 증착하였으며 이 조건에서의 물성을 SIMS, XPS, ESR, AFM, spectrophoto-metry를 이용하여 비교 분석하였다. ECR plasma CVD방법으로 얻은 실리콘 질화막은 화학양론적 조성(Si/N=0.75)에 근접하는 막을 얻을 수 있었으며 표면 평활도와 가시광투과도가 가장 우수한 결과를 얻었다. 저온 증착법인 PECVD로 얻은 막은 Si/N비가 약 0.86정도이고 산소와 수소의 불순물함량이 가장 높게 나타났다. SiH$_{2}$CI$_{2}$를 이용한 LPCVD막의 경우는 Si-rich조성을 가지지만 수소 불순물의 함량이 가장 작게 나타났고 표면거칠기는 가장 나쁘게 나타났다. 그러나 위의 방법으로 얻은 실리콘 질화막의 최대 가시광투과도는 633nm파장에서 모두 90%이상의 값을 나타내었고, 또한 표면 평활도도 0.64-2.6nm(rms)로 현재 연구되고 있는 다른 X선 투과막재료보다 월등히 우수한 결과를 보였다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.05a
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• pp.103-104
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• 2015

정확한 두께와 조성 제어, 훌륭한 재현성의 박막을 형성할 수 있는 Atomic layer deposition 방법으로 증착시킨 ZnO 박막은 여러 분야에 적용될 수 있기 때문에 최근 많은 주목을 받고 있다. ALD-ZnO 박막을 형성하기 위하여 가장 흔히 사용되는 전구체 (precursor)와 반응체 (reactant)는 DEZ(DiethylZinc)와 $H_2O$이다. 그러나 DEZ 전구체를 사용한 ALD-ZnO 박막은 낮은 열적 안정성이 문제로 지적되어져 왔으며, 또한 여러 분야의 적용 및 산업화를 위해서는 높은 증착률, 큰 범위의 전기적 저항, 높은 투과도가 필요로 한다. 본 연구에서는 atomic layer deposition 기법을 통해 열적 안정성을 가진 새로운 전구체인 DEZDMEA ($Et_2Zn:NEtMe_2$)을 사용하여 ZnO 박막을 증착하였다. DEZDMEA ($Et_2Zn:NEtMe_2$) 및 $H_2O$ 주입 시간에 따른 증착률와 전기적 성질, 투과도를 조사하였다.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.256-259
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• 2000

Ethanol fermentration of glucose by a strain of Zymomonas mobilis KCTC 1535 was studied in membrane recycle bioreactor, which was coupled with closs flow hollow fiber membrane. The maximum values of product yields and productivity are 0.4685g total ethanol/ g glucose, 14.05g total ethanol/ L/h, respectively The pervaporation performance of the PDMS menbrane has been investigated for the separation of binary mixtures of EtOH/water at $50^{\circ}C{\sim}70^{\circ}C$. The optimum conditions of feed concentration, temperature, feed solution flow rates is determined to be 8%, $70^{\circ}C$, 492ml/min, respectively. An ethanol permselectivity of 7.5 and flux of $0.04kg/m^2/hr$ were obtained with these membrane

• Applied Chemistry for Engineering
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• v.29 no.2
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• pp.196-200
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• 2018

In this study, the intermediate layer in Pd-based hydrogen separation membrane was synthesized to minimize the surface roughness and defects using powder-type and sol-type metal oxides. The surface properties and gas permeation characteristics were analysed by SEM and $N_2$ gas permeation test. The coating layer composed of sol type metal oxides has smooth surface, especially the layer coated by $TiO_2$ sol has little pin holes, cracks and defects. The binary layer composed of powder type and sol type metal oxides has similar flux characteristics to a single sol type layer. The Pd-based composite membrane improved by the binary intermediate layer exhibited $0.32mol/m^2s$ of the hydrogen permeation flux with a selectivity ($H_2/N_2$) of ~10,890 at 672 K and a pressure difference of 1 bar.

• Membrane Journal
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• v.28 no.4
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• pp.233-242
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• 2018

To study gas membrane using GO (graphene oxide), the PEBAX [poly(ether-block-amide)]-GO polymer composite membrane was prepared by adding GO to PEBAX. Through this composite membrane, gas permeation characteristics for $H_2$, $N_2$, $CH_4$, and $CO_2$ were studied. As a result of the gas permeation test, the permeability of $N_2$, $CH_4$, and $CO_2$ to PEBAX-GO composite membranes gradually decreased as the GO content increased. On the other hand, the gas permeability of $H_2$ increased with the increase of GO content, and it was 21.43 barrer at the GO content of 30 wt%, which was about 5 times higher than that of PEBAX membrane. This is because the GO was easier to operate with a fast and selective gas transport channel for $H_2$ than other gases. The increased selectivity ($H_2/N_2$) and selectivity ($H_2/CH_4$) were influenced by the diffusion selectivity by the permeate gas size. The increased selectivity ($CO_2/N_2$) and selectivity ($CO_2/CH_4$) were more influenced by the solubility selectivity due to the affinity of $CO_2$ and GO for -COOH.

• Applied Chemistry for Engineering
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• v.9 no.2
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• pp.306-310
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• 1998

The soluble polyimides(PMDA/diamine/dianhydride) were prepared and investigated. After coating the prepared PMDA/diamine/dianhydride solution into the commercial tubular alumina ceramic membranes, gas permeation characteristics was investigated. $T_g{\prime}s$ of the polyimides were in the range of $337{\sim}358^{\circ}C$ and thermal stability was good. The polymer was soluble in NMP, DMAc, DMSO, THF, and m-cresol. The adhesion between the alumina membrane and the soluble polyimide was excellent. The soluble polyimide/alumina membranes containing 6FDA showed the highest permeability among others. The permeability of nitrogen of PMDA/1,3PDA/6FDA-alumina membrane was about $7.6{\times}10^{-7}(mol/m^2{\cdot}Pa{\cdot}s)$ in the gas permeation experiments. The ideal separation factor of $O_2/N_2$ and $H_2/N_2$ in PMDA/1,3PDA/6FDA-alumina membrane were 6.19, and 70.0, respectively.