• Membrane and Water Treatment
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• v.10 no.4
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• pp.287-298
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• 2019

Lotus leaf has a special dual micro and nano surface structure which gives its highly hydrophobic surface characteristics and so-called self cleaning effect. In order to endow PVDF hollow fiber membrane with this special structure and improve the hydrophobicity of membrane surface, PVDF hollow fiber composite membranes was obtained through the immersion coating of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) dilute solution on the outside surface of PVDF support membrane. The prepared PVDF composite membranes were used in the vacuum membrane distillation (VMD) for the desalination. The effects of PVDF-HFP dilute solution concentration in the dope solution and coating time on VMD separation performance was studied. Membranes were characterized by SEM, WCA measurement, porosity, and liquid entry pressure of water. VMD test was carried out using $35g{\cdot}L^{-1}$ NaCl aqueous solution as the feed solution at feed temperature of $30^{\circ}C$ and the permeate pressure of 31.3 kPa. The vapour flux reached a maximum when PVDF-HFP concentration in the dilute solution was 5 wt% and the coating time was kept in the range of 10-60 s. This was attributed to the well configuration of micro-nano rods which was similar with the dual micro-nano structure on the lotus leaf. Compared with the original PVDF membrane, the salt rejection can be well maintained which was greater than 99.99 % meanwhile permeation water conductivity was kept at a low value of $7-9{\mu}S{\cdot}cm^{-1}$ during the continuous testing for 360 h.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.2
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• pp.85-92
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• 2009

Polymer electrolyte membrane (PEM) fuel cells are a promising technology for short-term power generation required in residential and automobile applications. Proper management of water has been found to be essential for improving the performance and durability of PEM fuel cells. This study investigated the liquid water exhaust capabilities of various flow channels having different geometries and surface properties. Three-pass serpentine flow fields were prepared by patterning channels of 1 mm or 2 mm width onto hydrophilic Acrylic plates or hydrophobic Teflon plates, and the behaviors of liquid water in those flow channels were experimentally visualized. Computational fluid dynamics (CFD) simulations were also conducted to quantitatively assess the liquid water exhaust capabilities of flow channels for PEM fuel cells. Numerical results showed that hydrophobic flow channels have better liquid water exhaust capabilities than hydrophilic flow channels. Flow channels with curved corners showed less droplet stagnation than the channels with sharp corners. It was also found that a smaller width is desirable for hydrophobic flow channels while a larger width is desirable for hydrophilic ones. The above results were explained as being due to the different droplet morphologies in hydrophobic and hydrophilic channels.

• Membrane Journal
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• v.31 no.5
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• pp.327-332
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• 2021

The use of membranes for MBRWG (Membrane Bioreactor for Waste Gas) treatment can provide highly selective separation of a waste gas stream followed by effective biological removal. MBRWG have several potential advantages, among which the most distinctive one is separation of gas and liquid phases at each side of membrane potentially allowing the optimal biomass control toward effective biodegradation of target gases as well as biofilm activation. This advantage becomes especially favorable for removal of hydrophobic toxic gases, such as xylene, by MBRWG systems, because the mass transfer, the toxicity, and thereby the biodegradation of hydrophobic gas treatment requires sensitive handling of liquid stream and water control near biofilm. Among various membranes for MBRWG treatment, PDMS-hollow fiber membranes provide the high gas mass transfer. Despite lower specific surface areas, capillary type membranes are also applied current MBRWG studies. In addition to the main application of membranes as biofilm supporter in MBRWG systems, there can be another application of membranes in a posterior process for removal of residual gases or dusts emitted from conventional biological waste gas treatment processes.

• BMB Reports
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• v.34 no.2
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• pp.130-133
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• 2001

The amino acid sequences of 130 kDa and 72 kDa proteins responsible for the larvicidal activity of Bacillus thuringiensis var israelensis (Bti) were analyzed by hydrophobic moment plots. A search for highly amphiphilic $\alpha$-helices was made in these proteins using the helical hydrophobic moment as a criterion of amphiphilicity The protein segments of the largest hydrophobic moments were analyzed. In the present communication we report the surface seeking helices in 130 kDa and 72 kDa proteins of Bacillus thuringiensis var israelensis. It is assumed that the surface seeking segments may participate in one of the membrane-related functions of Bacillus thuringiensis.

• Journal of the Korean Magnetic Resonance Society
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• v.15 no.1
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• pp.1-13
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• 2011

9Pbw2 is a 9-mer analog of protaetiamycine derived from the larvae of the beetle Protaetia brevitarsis. Previously, we designed four 9-mer peptide analogues to optimize the balance between the hydrophobicity and cationicity of the peptides and to increase bacterial cell selectivity. Among them, 9Pbw2 has high antibacterial activity without cytotoxicity. The results obtained in previous study suggest that the bactericidal action of 9Pbw2 may be attributed to the inhibition of the functions of intracellular components after penetration of the bacterial cell membrane. In order to understand structure-activity relationships, we determined the three-dimensional structure of 9Pbw2 in 200 mM DPC micelle by NMR spectroscopy. 9Pbw2 has one hydrophobic turn helix from $Trp^3$ to $Arg^8$ and positively charged residues at the N- and C-terminus. This result suggested that positively charged residues from position at the C-terminus in 9Pbw2 may be important for the primary binding to the negatively charged phospholipid head groups in bacterial cell membranes and hydrophobic residues in the middle portion face toward the acyl chains of the hydrophobic lipid in the bacterial cell membrane.

• Proceedings of the Membrane Society of Korea Conference
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• 1996.04a
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• pp.40-41
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• 1996

기존에 membrane의 소재로 사용되어 왔던 Polyethersulfone은 막 제조 특성이 우수하고 여러 가지 환경에 대한 저항성이 뛰어나서 많이 이용되어 왔지만 소수성을 띠므로 농도분극과 fouling등 많은 문제점을 안고 있다. 이런 문제점을 극복하기 위하여 친수성의 도입, 물리적, 화학적 세척등 여러 가지 방법을 사용하고 있고 본 연구에서는 hydrophobic Polyethersulfone에 hydrophilic Sulfonate group(-SO$_3$H)을 도입하여 이와같은 문제를 극복하고자 했다. 본 연구에서 사용한 sulfonating agent로는 Chlorosulfonic acid (in CCl$_4$)를 사용하였다.

• Proceedings of the Membrane Society of Korea Conference
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• 2004.11a
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• pp.93-96
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• 2004

• Proceedings of the Membrane Society of Korea Conference
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• 2004.05b
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• pp.102-105
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• 2004

산업 발전에 따른 각종 유기용제 및 휘발성유기혼합물(VOCs)의 사용이 점차 증가하는 실정이다. 그러나 유기용제들은 많은 양이 대기중 및 수중으로 방출되고 있으며, 이는 환경적으로 악영향을 끼칠 뿐 아니라 경제적으로 막대한 손실이 아닐 수 없다. 최근 VOCs의 회수에 대한 여러 분야에서 광범위하게 연구되어지고 있고, 이중 막분리 공정은 여러 가지 장점을 가지고 있어 기존의 공정을 대체할 수 있는 잠재력을 가지고 있다.(중략)

• Proceedings of the Membrane Society of Korea Conference
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• 2005.05a
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• pp.161-163
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• 2005

• Proceedings of the Membrane Society of Korea Conference
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• 2005.11a
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• pp.287-290
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• 2005