• Korean Chemical Engineering Research
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• v.50 no.3
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• pp.556-561
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• 2012

In this study, the effect of properties of gas diffusion layer (GDL) on the performance of polymer electrolyte membrane fuel cell (PEMFC) was investigated using the numerical simulation. The multi-phase mixture ($M^2$) model was used to calculate liquid water saturation and oxygen concentration in GDL. GDL properties, which were contact angle, porosity, gas permeability and thickness, were changed to investigate the effect of GDL properties on the performance of PEMFC. The results demonstrated that performance of PEMFC was increased with increasing contact angle and porosity of GDL, but decreased with increasing thickness of GDL. The liquid water saturation was decreased but oxygen concentration was increased at the GDL-catalyst layer interface, because the mass transfer resistance decreased as the porosity and contact angle increased. On the other hands, as the thickness of GDL increased, pathway for liquid water and oxygen gas became longer, and then mass transfer resistance increased. For this reason, performance of PEMFC decreased with increasing thickness of GDL.

• Applied Chemistry for Engineering
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• v.19 no.6
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• pp.633-639
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• 2008

Polysulfone membranes were prepared via the phase inversion process. Toluene was added as a nonsolvent additive in the casting solution containing a mixture of polysulfone and n-methylpyrrolidone. When prepared via the diffusion-induced process using isopropanol as a precipitation nonsolvent, the solidified membranes revealed a similar asymmetric structure irrespective of the addition of toluene, presenting both a dense skin layer and a sponge-like support layer. The added toluene played a role of enhancing liquid-liquid phase separation of the casting solution, and skin layer thickness of a prepared membrane increased with toluene content in the casting solution. On membrane performance, the solute rejection showed a uniform behavior irrespective of the addition of toluene. However, in spite of the significant increase in dense skin layer thickness, the water permeation through the membrane prepared with 60 wt% toluene revealed five times as much flux, compared with that of the membrane prepared without toluene additive.

• Clean Technology
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• v.13 no.1 s.36
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• pp.79-84
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• 2007

Separation of ethylene from ethane and propylene from propane have been conducted using facilitated olefin transport membrane with SPEEK-Ag (Ag substituted sulfonated poly(ether ether ketone)). SPEEK was prepared by the sulfonation of PEEK using cone. $H_2SO_4$ and the reaction time affected the degree of sulfonation (DS) of the resulting SPEEK. SPEEK-Ag composite membrane was formed by soaking SPEEK in the polyester support into the Ag salt solution. With increasing the concentration of SPEEK in MeOH, the thickness of SPEEK on the polyester increased. The selectivity and the flux of SPEEK-Ag membrane for the separation of ethylene/ethane and propylene/propane were changed by the thickness of SPEEK layer on the top of polyester support. The anion of silver salt also affects the membrane performance.

• Archives of Pharmacal Research
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• v.27 no.6
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• pp.653-661
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• 2004

Fluorescence probes located in different membrane regions were used to evaluate the effect of dopamine$.$HCI on the structural parameters (transbilayer lateral mobility, annular lipid fluidity, protein distribution, and thickness of the lipid bilayer) of synaptosomal plasma membrane vesicles (SPMV), which were obtained from the bovine cerebral cortex. An experimental procedure was used based on selective quenching of 1,3-di(1-pyrenyl)propane (Py-3-Py) by trinitrophenyl groups, and radiationless energy transfer from the tryptophan of membrane pro-teins to Py-3-Py and energy transfer from Py-3-Py monomers to 1-anilinonaphthalene-8-sulfonic acid (ANS) was also utilized. Dopamine$.$HCI increased both the bulk lateral mobility and annular lipid fluidity, and it had a greater fluidizing effect on the inner monolayer than on the outer monolayer. Furthermore, the drug had a clustering effect on membrane proteins.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.98.2-98.2
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• 2011

For optimal performance of a proton exchange membrane fuel cell (PEMFC), the membrane electrode assembly (MEA) requires hydration, and the membrane's conductivity depends on water content. A humidifier is required to ensure that the reactant gas, usually hydrogen and air, is hydrated before entering the fuel cell. Dry membrane operation or improper hydration causes performance degradation. Typically, the humidification of a fuel cell is carried out by means of an internal or external humidifier. A membrane humidifier is applied to the external humidification of transportation or residential power generation fuel cell due to its convenience and high performance. In this study, The experiments were constructed with a plate-type membrane humidifier in terms of geometric parameters and operating parameters. The results show that the temperature and pressure, the channel length, the membrane thickness and gas flow rate are critical parameters affecting the performance of the humidifier.

• Membrane Journal
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• v.9 no.1
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• pp.51-62
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• 1999

The recovery of trace volatile organic components from water by pervaporation was investigated. Permeation experiments through homogeneous polydimethylsiloxane(PDMS) membrane was carried out and the effect of feed concentrations and membrane thicknesses on the permeation characteristics were investigated. A solution-diffusion model is used to describe the pervaporation transport mechanism. In homogeneous PDMS membrane it appeared that the selectivities of MEK and toluene are constant, and that organic flux has a linear relationship with feed concentration. These results indicate that the coupling effects between organics were negligible. The selectivity of PDMS membranes is invariant with respect to the membrane thickness. The intrinsic membrane permeability of organic components determined by using a solution-diffusion model. Comparing with various composite type membrane, the membrane using PEG treated nonwoven fabric as sublayer showed the best performance in VOC recovery by pervaporation.

• Journal of the Korean institute of surface engineering
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• v.39 no.6
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• pp.255-262
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• 2006

Pd-Cu alloy membrane for hydrogen separation was fabricated by sputtering and Cu reflow process. At first, the Pd and Cu was continuously deposited by sputtering method on oxidized Si support, the Cu reflow process was followed. Microstructure of the surface and permeability of the membrane was investigated depending on various reflow temperature, time, Pd/cu composition and supports. With respect to our result, Pd-Cu thin film (90 wt.% Pd/10 wt.% Cu) deposited by sputtering process with thickness of $2{\mu}m$ was heat-treated for Cu reflow The voids of the membrane surface were completely filled and the dense crystal surface was formed by Cu reflow behavior at $700^{\circ}C$ for 1 hour. Cu reflow process, which is adopted for our work, could be applied to fabrication of dense Pd-alloy membrane for hydrogen separation regardless of supports. Ceramic or metal support could be easily used for the membrane fabricated by reflow process. The Cu reflow process must result in void-free surface and dense crystalline of Pd-alloy membrane, which is responsible for improved selectivity oi the membrane.

• Polymer(Korea)
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• v.32 no.4
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• pp.328-333
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• 2008

The osmotic delivery systems are based on osmosis. The transverse diffusion of water through a porous membrane from a medium with a low osmotic pressure to a medium with a high osmotic pressure. Nifedipine tablet dosage forms of Procardia $XL^{(R)}$(Pfizer) and $Adalat^{(R)}$(Bayer) are commercialized systems of this type that push-pull osmotic tablet operates successfully in delivering water-insoluble drugs. We prepared osmotic pellet system by fluidized bed coating method, and model-drug used nifedipine. The osmotic pellet system was composed of the core material. the swelling and osmotic pressure layer, the drug coating layer, and the porous membrane. This work is performed to investigate the effect of different factors, such as composition and thickness of membrane. The osmotic pellet has been successfully prepared by fluidized bed coating technology. The drug release behavior depended on the increase of CA ratio and thickness in porous membrane. The morphology of the osmotic pellet before and after the dissolution test were observed by SEM. In conclusion, we found that the drug release of osmotic pellet depended on the composition and coating thickness of porous membrane.

• Korean Journal of Food Science and Technology
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• v.31 no.3
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• pp.771-777
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• 1999

The structural function of three egg membrane layers and cuticle layer, and the effectiveness of 5 film coatings (chitosan, starch, gelatin, dextrin, mineral oil) on the prevention of Salmonella enteritidis penetration was investigated using confocal scanning laser microscopy (CSLM). Diameters of outer membrane fibers, inner membrane fibers and limiting membrane particles in eggshell were $1.5{\sim}7.2$, $0.8{\sim}2.0$ and $0.1{\sim}1.4\;{\mu}m$, respectively and average thicknesses were 10.0, 3.5, $3.6\;{\mu}m$, respectively. Average thickness of cuticle layer was $6.0\;{\mu}m$ and cuticle layer covered $40{\sim}80%$ of total eggshell surface. Average coating films thickness for chitosan, starch, gelatin, dextrin and mineral oil were 2.2, 2.5, 3.9, 3.6 and $5.0\;{\mu}m$, respectively. After immersion process eggshell surface was almost completely covered by coating films. Chitosan coating was most effective among 5 film coatings in inhibiting growth of Salmonella enteritidis. Penetration process of Salmonella enteritidis through eggshell was investigated by multicolor imaging using CSLM and plate counting. Cuticle layer was the most important structure in blocking the penetration. Among 5 film coatings, chitosan showed the best and similar effectiveness with cuticle layer.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.183-185
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• 2002

Heavy ion and proton therapy necessitate range weeks, which are time consuming. Three types of variable compensator, membrane type liquid variable compensator, are proposed by some of the authors to overcome the difficulties, by those arbitrarily thickness distribution of compensator obtained from treatment planning is created at the site of treatment. None of the ideas, however, is yet realized. In this research, we are trying to construct prototype membrane-type liquid variable compensator. This variable compensator partitions air and liquid with elasticity membrane and changes the surface of the elasticity membrane with the thread. The air and oil move through holes to and from the out of beam side of two boxes in which they are contained. The boxes are made of Plexiglas(PMMA), the thread which is made of nylon, the elasticity film which is made from latex for the moment.