• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.471-473
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• 2006

An object of the present study is to provide a hollow fiber membrane humidifier capable of improving the humidification efficiency while lowering the pressure loss, and is suitably usable for PEMFC(Polymer Electrolyte Membrane Fuel Cell). The performance of PEMFC is decisively dependent on the humidity of the electrolyte membrane(fluorinated membrane) and a humidifier plays an important role in moisturizing electrolyte membrane. Especially this humidifier is adaptable for lower price to promote the commercialization of fuel cell vehicles and is passive type to be power free and to be volumetrically optimized. In this research, we propose the substitutes for the expensive fluorinated materials and the optimum dry-jet wet spinning conditions of hollow fiber membrane to get the fuel cell humidifier. In addition to that we established the standard method of evaluating the moisturizing performance of the humidifier of various materials.

• Carbon letters
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• v.3 no.1
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• pp.33-38
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• 2002

Petroleum based isotropic pitch was spun into short fiber by melt-blown spinning technology. The processing parameters chosen were air velocity, die temperature, and throughput rate of the pitch within the ranges of experimental tolerances. The fiber diameter was reduced to $6{\mu}m$ by increases of hot air velocity, and spin die temperature. Also, the fiber diameter was strongly dependent on the throughput rate of the pitch and jet speed of hot air through the spinnerets. Even fibers with $10{\mu}m$ diameter were produced at throughput rate of $0.17g/min{\cdot}hole$ and at die temperature of $290^{\circ}C$.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.177-179
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• 2007

An object of the present study is to provide a hollow fiber membrane humidifier capable of improving the humidification efficiency while lowering the pressure loss, and is suitably usable for PEMFC(Polymer Electrolyte Membrane Fuel Cell). The performance of PEMFC is decisively dependent on the humidity of the electrolyte membrane(fluorinated membrane) and a humidifier plays an important role in moisturizing electrolyte membrane. Especially, this humidifier is a passive type(power-free) item and is volumetrically optimized. In this research, we propose the substitutes for the expensive fluorinated humidifier materials and the optimum dry-jet wet spinning conditions of hollow fiber membrane. In addition to that, This study will present an performance of an humidifier and compare computational results with the experimental data.

• Membrane and Water Treatment
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• v.9 no.1
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• pp.43-51
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• 2018

Hollow fiber (HF) membranes are gaining wide interest over flat membranes due to their compaction and high area to surface volume ratio. This work addresses the fabrication of HF from polysulfone (PS) and polyethersulfone (PES) using N-methylpyrrolidone (NMP) as solvent in addition to other additives to achieve desired characteristics. The semi-pilot spinning system includes jacketed vessel, four spinneret block, coagulation and washing baths in addition to dryer and winder. Different parameters affecting dry-wet spinning phase inversion process were investigated. Dope compositions of PES, NMP and polyvinyl pyrrolidone (PVP) of varying molecular weights as additive were addressed. Some critical parameters of importance were also investigated. Those include dope flow rate, air gap, coagulation & washing baths and drying temperatures. The measured dope viscosity was in the range from 1.7 to 36.5 Pa.s. Air gap distance was adjusted from 20 to 45 cm and coagulation bath temperature from 20 to $46^{\circ}C$. The HF membranes were characterized by scanning electron microscope (SEM), atomic force microscope (AFM) and mechanical properties. Results indicated prevalence of finger like structure and average surface roughness from about 29 to 78.3 nm. Profile of stress strain characteristics revealed suitability of the fibers for downstream interventions for fabrication of thin film composite membrane. Different empirical correlations were formulated which enable deeper understanding of the interaction of the above mentioned variables. Data of pure water permeability (PWP) confirmed that the fabricated samples fall within the microfiltration (MF)-ultrafiltration (UF) range of membrane separation.

• Membrane Journal
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• v.2 no.1
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• pp.67-73
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• 1992

The effects of after-treatment condition on the permeability of polysulfone hollow fiber membranes were investigated. It was well known that the permeability of and the rejection of hollow fiber membranes prepared by dry-wet spinning technique was highly affected by spinning conditions such as composition of spinning solution, inner and outer coagulant and spinning height. But these are also governed by after-treatment condition such as drying, hot water treatment and glycerine treatment. Since it was difficult to remove DMAc and NMP in membranes by washing with in cold water and even traces of such solvent affected the reproducibility of the membrane characteristics, the hot water-treatment should be required.

• Membrane and Water Treatment
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• v.1 no.3
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• pp.215-230
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• 2010

Poly(vinylidene fluoride-co-hexafluoropropylene), PVDF-HFP, hollow fiber membranes were prepared by the dry/wet spinning technique using different polyethylene glycol (PEG) concentrations as non-solvent additive in the dope solution. Two different PEG concentrations (3 and 5 wt.%). The morphology and structural characteristics of the hollow fiber membranes were studied by means of optical microscopy, scanning electron microscopy, atomic force microscopy (AFM) and void volume fraction. The experimental permeate flux and the salt (NaCl) rejection factor were determined using direct contact membrane distillation (DCMD) process. An increase of the PEG content in the spinning solution resulted in a faster coagulation of the PVDF-HFP copolymer and a transition of the cross-section internal layer structure from a sponge-type structure to a finger-type structure. Pore size, nodule size and roughness parameters of both the internal and external hollow fiber surfaces were determined by AFM. It was observed that both the pore size and roughness of the internal surface of the hollow fibers enhanced with increasing the PEG concentration, whereas no change was observed at the outer surface. The void volume fraction increased with the increase of the PEG content in the spinning solution resulting in a higher DCMD flux and a smaller salt rejection factor.

• International Journal of Industrial Entomology and Biomaterials
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• v.30 no.2
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• pp.75-80
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• 2015

The wet spinning of silk solution has attracted researchers' attention because of 1) unique properties of silk as a biomedical material and 2) easy control of the structure and properties of the regenerated silk fiber. Recently, studies have reported that different silkworm varieties produce silk with differences in the molecular weight (MW) and other mechanical properties of the regenerated silk fibroin (SF) film. In this study, we look at the effect of different Bombyx mori varieties on the wet spinning of SF. Although five regenerated SFs from different silkworm varieties have different MWs and solution viscosity, the wet spinnability and post drawing performance of regenerated SFs were not different. This result is due to low variability in the MW of the regenerated SF samples from the different silkworm varieties. In addition, unlike regenerated SF films, the mechanical properties of wet spun regenerated SF filament were not affected by silkworm variety. This result suggests that the mechanical properties of wet spun SF filament are less affected by MW than those of SF film are.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.82-87
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• 2012

Research and development of the spinning system which become bigger, faster and more detailed has been making progress continuously due to the increasing use of yarn which is considered as raw material to make industrial goods such as tire cord, air bag, filter, seatbelt and fiber-optic cable along with a remarkable growth of industry. In this paper, the desirable procedure and design requirements concerning a method of vibration reduction for "Godet Roller" considered as the main source of high vibration in the spinning system were suggested, and then verified those by analysis and actual test.

• Journal of the Korean Ceramic Society
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• v.33 no.10
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• pp.1079-1088
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• 1996

Discontinuous ${\gamma}$-LiAlO2 fibers for fiber-reinforcing MCFC matrixes have been produced by the sol-gel process using the centrifugal spinning apparatus of the Rotary type. Gel fibers could be obtained through spinning of stable LiAlO2 complex polymetric sols under the optimum spinning conditions (hollow-disc rotating velocity 9000 rpm sol feeding rate of 4ml/min flowing N2 temperature of 4$0^{\circ}C$ and flowing N2 pressure of 4 bar). It was found that defect free and densified ${\gamma}$-LiAlO2 fibers with the relative density of 98% and the mean diameter of 4.7${\mu}{\textrm}{m}$ were prepared when the spinned fibers were heat-treated to 100$0^{\circ}C$ on the specified heating schedule. in particular the mean diameter and length of fibers could be controlled by the pressure of flowing N2 and the chopping-sieving method respectively.

• Proceedings of the Membrane Society of Korea Conference
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• 2000.11a
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• pp.50-53
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• 2000