• Membrane Journal
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• v.17 no.4
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• pp.345-351
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• 2007

In this research, by using the fluorine gas, the poly(ether sulfone) (PES), the polysulfone (PSf), and the poly-vinylidenefluoride (PVDF) membranes were modified to improve the performance of the optional Gas-Liquid Contactor The SEM, surface contact angle, XPS, and the water transmission minimum pressure test was performed in order to examine the characteristics of which is surface modified. As a result of looking into the surface morphology of from the SEM measurement, we could know that the roughness of the membrane surface increased as the fluorine processing time increased. $-CH_2$, and the perfluoro group of $-CH_3$ were chemically combined with the surface fluorine conversion film surface and the hydrophobicity was exposed to be increased. Moreover, we could know that as the surface fluorinated processing time increased from the surface contact angle and water transmission minimum pressure test, the measured value increased and the overall characteristics were improved.

• Membrane Journal
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• v.30 no.1
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• pp.9-20
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• 2020

Membranes are used in most processes of biopharmaceutical production. It is used for pretreatment of other processes, separation of impurities in the process, virus removal, control of products concentration and buffer solution exchange. Virus filters play an important role in ensuring product efficacy and stability because viral contamination of biopharmaceuticals for humans is a sensitive issue that is directly related to serious clinical outcomes. Virus filters typically have complex multilayer structures made of various polymers such as surface-modified PVDF, PES, CRC. Depending on the manufacturer, filters have different pore structures and shapes, such as symmetric or asymmetric, and is used in the form of pleated membrane, flat sheets or hollow fibers. Virus filters are exclusively supplied by few foreign companies such as Asahi Kasei, Millipore, Pall and Sartorius. Replacing virus filters can be time consuming and expensive, including approval from regulatory agencies through validation. As localization has become important due to Japan's recent export regulations, it is necessary to increase the degree of technical independence.

• Membrane Journal
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• v.16 no.4
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• pp.268-275
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• 2006

Novel SILEMs were prepared by multi-stage phase separation process combined by the low temperature phase separation (LTPS) and the high temperature phase separation (HTPS) using room temperature ionic liquids (RTILs) which have a high ionic conductivity. PVDF and imidazolium series ionic liquids were used as membrane material and electrolyte, respectively. To study the ion conducting properties, the SILEMs were tested using LCR meter at temperature controlled from 30 to $130^{\circ}C$. Under humid conditions, with increasing temperature from 30 to $100^{\circ}C$, the ion conductivity of the cast $Nafion^{(R)}$ membrane increased linearly, but then started to decrease after $100^{\circ}C$. However, in the case of the SILEMs, with increasing operating temperature, the ion conductivity increased. Also, the ion conductivity behaviors of the SILEMs were almost same, regardless of humidity. The ion conductivity of the SILEMs was $2.7{\times}10^{-3}S/cm$ and increased almost linearly up to $2.2{\times}10^{-2}S/cm$ with increasing temperature to $130^{\circ}C$. The effects of an inorganic filler on the physical properties of the SILEMs were studied using the $SiO_2$. The addition of $SiO_2$ could improve the mechanical strength of the SILEMs, though the ionic conductivity was decreased slightly.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.9
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• pp.542-547
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• 2017

This paper was to analyze the membrane characterization of hydrophilicity, surface morphology and membrane chemical anlysis of three commercial microfiltration/ultrafiltration membranes, and evaluate the filtration performance of a seawater to assess the availability for pretreatment of desalination process. From the results of contact angle, Mem-3, fabricated with polyacrylonitrile, was highly hydrophilic. It find out that Mem-3 has more anti-biofouling property. In Field emission scanning electron microscope (FESEM), Mem-1 (polyethylene) and Mem-2 (Polyvinylidenefluoride) showed the sponge-like shape and Mem-3 showed finger-like shape. Membrane chemical analysis by energy dispersive spectrometer (EDS) presented that Mem-2 was mostly fluoride and Mem-3 had s high ratio of N (32.47%) due to the nitrile group. The permeation flowrate per time on suction pressures using deionized water (D.I. water) tends that permeation rate of Mem-3 more increased when the pressure was increased compared to other membranes. From the results of turbidity and total suspended solids (TSS) removal, turbidity of permeate was 0.191 NTU to 0.406 NTU and TSS was 2.2 mg/L to 3.0 mg/L in all membranes, indicating that it was not suitable for the pretreatment of seawater desalination by short-term experiments.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2451-2456
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• 2003

In biological cell manipulation, manual thrust or penetration of an injection pipette into an egg is currently performed by a skilled operator, relying only on visual feedback information. Massive load of various micro injection of either genes, fluid or cells in the postgenomic era calls a more reliable and automatic micro injection system that can test hundreds of genes or cell types at a single experiment. We initiated to study cellular force sensing in zebrafish eggs as the first step for the development of a more controllable micro injection system by any inexperienced operator. Zebrafish eggs at different developmental stages were collected and an integrated biomanipulation system was employed to measure cellular force during penetrating the egg envelope, the chorion. First of all, the biomanipulation system integrated with cellular force sensing instrument is implemented to measure the penetration force of cell membranes and characterize mechanical properties of zebrafish embryo cells. Furthermore, implementation of cellular force sensing system and calibration are presented. Finally, the cellular force sensing of penetrating cell membranes at each developmental stages was experimentally performed. The results demonstrated that the biomanipulation system with force sensing capability can measure cellular force at real-time while the injection operation is undergoing. The magnitude of the measured force was in the range of several hundreds of uN. The precise real-time measurement should provide the first step forwards for the development of an automatic and reliable injection system of various materials into biological cells.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.714-717
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• 2007

In this study, a novel actuator was developed by employing the newly-synthesized ionic networking membrane (INM) of poly (styrene-alt-maleic anhydride) (PSMAn)-incorporated poly (vinylidene fluoride) (PVDF). Based on the same original membrane, various samples of INM actuator were prepared through different reduction times with the electroless-plating technique. The as-prepared INM actuators were tested in terms of surface resistance, platinum morphology, resonance frequency, tip displacement, current and blocked force, and their performance was compared to that of the widely-used traditional Nafion actuator. Scanning electron microscope (SEM) and transmission electron microscopy (TEM) revealed that much smaller and more uniform platinum particles were formed on the surfaces of the INM actuators as well as within their polymer matrix. Although excellent harmonic response was observed for the newly-developed INM actuators, this was found to be sensitive to the applied reduction times during the fabrication. The mechanical displacement of the INM actuator fabricated after optimum reduction times was much larger than that of its Nafion counterpart of comparable thickness under the stimulus of constant and alternating current voltage.

• Journal of the Korean Solar Energy Society
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• v.34 no.5
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• pp.23-31
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• 2014

This study was accomplished to get the foundation design data of VMD(Vacuum Membrane Distillation) system for Solar Thermal VMD plant. VMD experiment was designed to evaluate thermal performance of VMD using PVDF(polyvinylidene fluoride) hollow fiber hydrophobic membranes. The total membrane surface area in a VMD module is $5.3m^2$. Experimental equipments to evaluate VMD system consists of various parts such as VMD module, heat exchanger, heater, storage tank, pump, flow meter, micro filter. The experimental conditions to evaluate VMD module were salt concentration, temperature, flow rate of feed sea water. Salt concentration of feed water were used by aqueous NaCl solutions of 25g/l, 35g/l and 45g/l concentration. As a result, increase in permeate flux of VMD module is due to the increasing feed water temperature and feed water flow rate. Also, decrease in permeate flux of VMD module is due to increasing salinity of feed water. VMD module required about 590 kWh/day of heating energy to produce $1m^3/day$ of fresh water.

• Journal of Microbiology and Biotechnology
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• v.18 no.11
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• pp.1836-1840
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• 2008

Bacteriocins are antimicrobial peptides that are produced by bacteria and toxic to bacterial strains closely related to the producer strain. It has previously been reported that Bacillus thuringiensis strain NEB17 and Bacillus thuringiensis subsp. kurstaki BUPM4 produce the bacteriocins thuricin 17 (3,162 Da) and bacthuricin F4 (3,160.05 Da), respectively. Here, we demonstrate that these bacteriocins have functional similarities and show a similar spectrum of antimicrobial activities against indicator strains. We also studied the effects of sterilization methods on the recovery and biological activities of these bacteriocins. They were completely degraded by autoclaving and the two were similarly affected by the tested filter membranes. Polyvinylidene fluoride (PVDF), polyestersulfone (PES), and cellulose acetate (CA) are suitable for filter sterilization of these bacteriocins. The two bacteriocins were stable across a range of storage conditions. These data will facilitate their utilization in food preservation or agricultural applications.

• Membrane and Water Treatment
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• v.11 no.5
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• pp.333-344
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• 2020

Advances in industrial development and waste management over several decades have reduced many of the impacts that previously affected ecosystems, however, there are still processes which discharge hazardous materials into environments. Among industries that produce industrial wastewaters, textile manufacturing processes play a noticeable role. This study was conducted to test a novel continuous combined commercial membrane treatment using polyvinylidene fluoride (PVDF), ultrafiltration (UF), and polyamide (PA) nanofiltration (NF) membranes for textile wastewater treatment. The synthetic textile wastewater used in this study contained sodium silicate, wax, and five various reactive dyes. The results indicate that the removal efficiency for physical particles (wax and resin) was 95% through the UF membrane under optimum conditions. Applying UF and NF hybrid treatment resulted in total effective removal of dye from all synthetic samples. The efficiency of sodium silicate removal was measured to be between 2.5 to 4.5% and 13 to 16% for UF and NF, respectively. The chemical oxygen demand in all samples was reduced by more than 85% after treatment by NF.

• Membrane Journal
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• v.27 no.3
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• pp.240-247
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• 2017

In this study, the heterogeneous ion exchange membranes prepared by the combination of the carbon electrode and mixed the cation and anion exchange polymers and polyvinylidene fluoride as the basic polymer together were made to recognize the efficiency of the salt removal for the application of the membrane capacitive deionization process. The mixing weight ratio of the solvent, basic polymer and ion exchange resin was 7 : 2 : 1 and this mixed solution was directly cast on the electrode. As for the operating conditions of the adsorption voltage and time, feed flow rate, desorption voltage and time of the feed solution NaCl 100 mg/L, the salt removal efficiencies (SRE) were measured. Apart from this NaCl, the $CaCl_2$ and $MgSO_4$ solutions were investigated in terms of SRE as well. Typically, SRE for NaCl 100 mg/L solution under the conditions of adsorption voltage/time, 1.5 V/3 min, desorption voltage/time -0.1 V/3 min, was shown 98%. And for the $CaCl_2$ and $MgSO_4$ solutions, the SREs of 70 and 59% were measured under the conditions of adsorption voltage/time, 1.2 V/3 min, desorption voltage/time -0.5 V/5 min, respectively.