• Korean Chemical Engineering Research
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• 제49권2호
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• pp.250-255
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• 2011

본 연구는 막 분리 공정을 이용한 것으로 수소의 에너지원을 이용가능한 메탄을 정제하기 위해 바이오가스 중 이산화탄소와 메탄의 분리 및 황화수소의 제거하고자 한다. 막은 건/습식 상전이 법을 이용하여 중공사공 형태로 제조하고 표면 실리콘 코팅 후 모듈을 제조하였다. 제조된 중공사 막의 구조특성을 확인하기 위해 전자주사 현미경 관찰을 통하여 치밀한 표면과 망상구조의 비대칭 구조를 확인하였다. 압력과 온도가 증가함에 따라 이산화탄소의 투과도는 증가하였고, 이산화탄소와 메탄의 선택도 역시 증가하는 것으로 나타났다. 혼합가스의 경우 압력 및 온도가 증가함에 따라 메탄 농도는 100%에 가까웠으며 이산화탄소와 황화수소의 제거효율도 증가하였다. Retentate 유량증가와 압력 온도감소에 따라 메탄 농도 감소 및 회수율이 증가하는 경향을 나타내었다.

• 멤브레인
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• 제25권2호
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• pp.123-131
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• 2015

PTMSP와 PDMS로부터 합성된 PTMSP/PDMS 그라프트 공중합체에 다공성 borosilicate를 0~5 wt% 첨가하여 PTMSP/PDMS-borosilicate 복합막을 제조하였다. 합성된 PTMSP/PDMS 그라프트 공중합체의 수평균분자량(${\bar{M}}_n$)은 460,000이었고, 중량평균분자량(${\bar{M}}_w$)은 570,000이었으며, 유리전이온도($T_g$)는 $33.53^{\circ}C$에서 나타났다. TGA 측정에 의하면 PTMSP/PDMS에 borosilicate가 첨가되면 복합막의 감량이 작아지고 감량이 완결되는 온도도 낮아졌다. SEM측정에 의하면 PTMSP/PDMS-borosilicate 복합막 내에 들어있는 borosilicate는 $1{\sim}5{\mu}m$ 크기로 분산되어 있었다. 기체투과 실험에 의하면 PTMSP/PDMS-borosilicate가 첨가되면서 자유부피, 공동, 기공률이 증가하여 기체투과가 용해확산에 의한 것보다 분자체거름, 표면확산, Knudsen 확산에 의해 일어나는 경우가 점차 증가하여 $H_2$와 $N_2$의 투과도는 증가하고 선택도($H_2/N_2$)는 감소하였다.

• 멤브레인
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• 제20권3호
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• pp.259-266
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• 2010

다공성 Poly(propylene) 분리막의 지지 하에 전해질 용액 (EC/DEC 1 : 1 혼합물 내의 $LiPF_6$ 1 M 용액) 내에서 DEGDMA [Di(ethylene glycol) dimethacrylate]의 $70^{\circ}C$ 열중합을 통하여 겔 고분자 전해질(GPE)막이 합성 되었다. 합성된 겔 고분자 전해질막의 이온전도도 및 전기화학적 안정성은 AC 임피던스법 및 CV (cyclic voltametry)법에 의하여 측정 평가하였다. 겔 고분자를 전해질로, 그리고 양극 및 음극으로는 각각 $LiMi_{0.8}Co_{0.2}O_2$ 및 graphite로 이용하여 리튬이온전지(LIB)도 제작하였다. 열중합을 통하여 리튬 이온전지에 적합한 이온전도도($10^{-3}\;S/cm$ 이상) 및 전기화학적 안정성을 보이면서 자체적인 성상을 유지하는 겔 고분자 전해질막을 얻을 수 있었다. 단량체 함량 5%의 전구체로 제작한 겔 고분자 전지는 단량체 함량이 7.0% 및 10.0%인 경우에 비하여 우수한 고율 및 충-방전 효율을 보였다.

• 한국표면공학회지
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• 제46권6호
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• pp.248-257
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• 2013

It is generally recognized that thin Pd-Cu alloy films fabricated by sputtering show a wide range of microstructures and properties, both of which are highly dependent on the sputtering conditions. In view of this, the present study aims to investigate the relationship between the performance of hydrogen separation membranes and the microstructure of Pd alloy films depending on sputtering deposition conditions such as substrate temperature, working pressure, and DC power. We fabricated thin and dense Pd-Cu alloy membranes by the micro-polishing of porous Ni support, an advanced Pd-Cu sputtered multi-deposition under the conditions of high substrate temperature / low working pressure / high DC power, and a followed by Cu-reflow heat-treatment. The result of a hydrogen permeation test indicated that the selectivity for $H_2/N_2$ was infinite because of the void-free and dense surface of the Pd alloy membranes, and the hydrogen permeability was 10.5 $ml{\cdot}cm^{-2}{\cdot}min^{-1}{\cdot}atm^{-1}$ for a 6 ${\mu}m$ membrane thickness.

• 상하수도학회지
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• 제22권1호
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• pp.131-140
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• 2008

The application of magnetic ion exchange resin($MIEX^{(R)}$) is effective for natural organic matter(NOM) removal and for control of the formation of disinfection byproducts(DBPs). NOM removal is also enhanced by adding $MIEX^{(R)}$ with coagulant such as polyaluminium chloride(PACl) in conventional drinking water treatment systems. In the application of $MIEX^{(R)}$, it is important to understand changes of NOM characteristics such as hydrophobicity and molecular weight distributions with $MIEX^{(R)}$ or $MIEX^{(R)}$+coagulant treatment.To observe characteristics of NOM by treatment with $MIEX^{(R)}$ or $MIEX^{(R)}$+coagulant, four major drinking water sources were employed. Results showed that the addition of $MIEX^{(R)}$ to coagulation significantly reduced the amount of coagulant required for the optimum removal of dissolved organic matter(DOC) and turbidity in the all four waters. The DOC removal was also increased approximately 20%, compared to coagulant treatment alone. The process with $MIEX^{(R)}$ and coagulant showed that complementary removal of hydrophobic and hydrophilic fraction of DOC. The combined processes preferentially removed the fractions of intermediate (3,000-10,000 Da) and low (< 500 Da) molecular weight. The microfiltration test showed that membrane cake resistance was decreased for waters with flocs from $MIEX^{(R)}$+coagulant. A porous layer was formed to $MIEX^{(R)}$ on the membrane surface and the layer consequently inhibited settling of coagulant flocs, which could act on a foulant.

• International Journal of Automotive Technology
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• 제8권6호
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• pp.761-769
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• 2007

The configuration of the flow channel on a bipolar plate of a proton exchange membrane fuel cell(PEMFC) for efficient reactant supply has great influence on the performance of the fuel cell. Recent demand for higher energy density fuel cells requires an increase in current density at mid voltage range and a decrease in concentration overvoltage at high current density. Therefore, an interdigitated flow channel where mass transfer rate by convection through a gas diffusion layer is greater than the mass transfer by a diffusion mechanism through a gas diffusion layer was recently proposed. This study attempts to analyze the i-V performance, mass transfer and pressure drop in interdigitated flow channels by developing a fully three dimensional simulation model for PEMFC that can deal with anode and cathode flow together. The results indicate that the trade off between performance and pressure loss should be considered for efficient design of flow channels. Although the performance of the fuel cell with interdigitated flow is better than that with conventional flow channels due to a strong mass transfer rate by convection across a gas diffusion layer, there is also an increase in friction due to the strong convection through the porous diffusion layer accompanied by a larger pressure drop along the flow channel. It was evident that the proper selection of the ratio of channel and rib width under counter flow conditions in the fuel cell with interdigitated flow are necessary to optimize the interdigitated flow field design.

• 분석과학
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• 제7권3호
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• pp.371-378
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• 1994

이 갈바니식 산소센서의 산소농도 측정범위는 0.0~20.0%이었다. 산소환원 전극으로 금 또는 은을 이용하여 산소농도 변화에 따른 재현성 있는 응답시간 및 감도를 얻었다. 산화전극으로는 Pb-Sn-Ca 합금을 이용하였다. 산소 선택 투과막은 소수성이며 다공성 물질인 테플론을 이용하여 두께 변화에 따른 온도($10{\sim}50^{\circ}C$) 및 습도(R. H 0~99%)에 미치는 영향을 연구하였다. 전해질은 아세트산납 완충 용액을 이용하여 출력전압을 증가시켰으며, 센서의 수명을 길게 하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.353-353
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• 2008

Carbon nanotubes (CNTs) are attractive for field emitter because of their outstanding electrical, mechanical, and chemical properties. Several applications using CNTs as field emitters have been demonstrated such as field emission display (FED), backlight unit (BLU), and X-ray source. In this study, we fabricated a CNT cathode using transparent ultra-thin CNT film. First, CNT aqueous solution was prepared by ultrasonically dispersing purified single-walled carbon nanotubes (SWCNTs) in deionized water with sodium dodecyl sulfate (SDS). To obtain the CNT film, the CNT solution in a milliliter or even several tens of micro-litters was deposited onto a porous alumina membrane through vacuum filtration process. Thereafter, the alumina membrane was solvated by the 3 M NaOH solution and the floating CNT film was easily transferred to an indium-tin-oxide (ITO) glass substrate of $0.5\times0.5cm^2$ with a film mask. The transmittance of as-prepared ultra-thin CNT films measured by UV-Vis spectrophotometer was 68~97%, depending on the amount of CNTs dispersed in an aqueous solution. Roller activation, which is a essential process to improve the field emission characteristics of CNT films, increased the UV-Vis transmittance up to 93~98%. This study presents SEM morphology of CNT emitters and their field emission properties according to the concentration of CNTs in an aqueous solutions. Since the ultra-thin CNT emitters prepared from the solutions show a high peak current density of field emission comparable to that of the paste-base CNT emitters and do not contain outgassing sources such as organic binders, they are considered to be very promising for small-size-but-high-end applications including X-ray sources and microwave power amplifiers.

• Membrane and Water Treatment
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• 제7권1호
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• pp.55-70
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• 2016

Microfiltration/ultrafiltration (MF/UF) Adsorptive polyamide-6 (PA-6) membranes were prepared using wet phase inversion process. The prepared PA-6 membranes are characterized by scanning electron microscopy (SEM), porosity and swelling degree. In this study, the membranes performance has examined by adsorptive removal of copper ions from aqueous solutions in a batch adsorption mode. The $PA-6/H_2O$ membranes display sponge like and highly porous structures, with porosities of 41-73%. Under the conditions examined, the adsorption experiments have showed that the $PA-6/H_2O$ membranes had a good adsorption capacity (up to 120-280 mg/g at the initial copper ion concentration ($C_0$) = 680 mg/L, pH7), fast adsorption rates and short adsorption equilibrium times (less than 1.5-2 hrs) for copper ions. The fast adsorption in this study may be attributed to the high porosities and large pore sizes of the $PA-6/H_2O$ membranes, which have facilitated the transport of copper ions to the adsorption. The results obtained from the study illustrated that the copper ions which have adsorbed on the polyamide membranes can be effectively desorbed in an Ethylene dinitrilotetra acetic acid Di sodium salt ($Na_2$ EDTA) solution from initial concentration (up to 92% desorption efficiency) and the PA-6 membranes can be reused almost without loss of the adsorption capacity for copper ions. The results obtained from the study suggested that the $PA-6/H_2O$ membranes can be effectively applied for the adsorptive removal of copper ions from aqueous solutions.

• 한국수소및신에너지학회논문집
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• 제32권4호
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• pp.228-235
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• 2021

Polymer electrolyte membrane fuel cells (PEMFC) are currently being used in various transport applications such as drones, unmanned aerial vehicles, and automobiles. The power required is different according to the type of use, purpose, and the conditions adjusted using a cell stack. The fuel cell stack is compressed to reduce the size and prevent fuel leakage. The unit cells that make up the cell stack are subjected to compression by clamping force, which makes geometrical changes in the porous media and it impacts on cell performance. In this study, finite elements method (FEM) and computational fluid dynamics (CFD) analysis for the deformed unit cell considering the effects of clamping force is performed. First, structural analysis using the FEM technique over the deformed gas diffusion layer (GDL) considering compression is carried out, and the resulting porosity changed in the GDL is calculated. The PEMFC model is then verified by a three-dimensional, two-phase fuel cell simulation applying the physical properties and geometry obtained before and after compression. The detailed simulation results showed different concentration distributions of fuel between the original and deformed geometry, resulting in the difference in the distribution of current density is represented at compressed GDL region with low oxygen concentration.