• Journal of Korean Society of Water and Wastewater
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• v.27 no.3
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• pp.363-371
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• 2013

In this study, effect of activated carbon size on flux and fouling of membrane was investigated on activated carbon and membrane hybrid system. The activated carbon was prepared with crushing and screening. The activated carbon was named by A100, B100, A200, B200, A325 and B325 due to size of activated carbon. The permeability for A100, B100, A200 and B200 showed no significant difference. However, the permeability for A325 and B325 was decreased rapidly and was lowed due to increase the concentration of NOM. Main resistance for A100, B100, A200 and B200 was identified as irreversible fouling. However main resistance for A325 and B325 was identified as reversible fouling. The smaller activated carbon adsorbs NOM faster than bigger particles, which can show high permeability at early stage of the operation and then showed faster decrease of permeability at end of the operation.

• Journal of Sensor Science and Technology
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• v.31 no.6
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• pp.366-370
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• 2022

A 12 ㎛ pixel-sized 360 × 240 microbolometer focal plane array (MBFPA) was fabricated using a complementary metaloxide-semiconductor (CMOS)-compatible process. To release the MBFPA membrane, an amorphous carbon layer (ACL) processed at a low temperature (<400 ℃) was deposited as a sacrificial layer. The thermal time constant of the MBFPA was improved by using serpentine legs and controlling the thickness of the SiNx layers at 110, 130, and 150 nm on the membrane, with response times of 6.13, 6.28, and 7.48 msec, respectively. Boron-doped amorphous Si (a-Si), which exhibits a high-temperature coefficient of resistance (TCR) and CMOS compatibility, was deposited on top of the membrane as an IR absorption layer to provide heat energy transformation. The structural stability of the thin SiNx membrane and serpentine legs was observed using field-emission scanning electron microscopy (FE-SEM). The fabrication yield was evaluated by measuring the resistance of a representative pixel in the array, which was in the range of 0.8-1.2 Mohm (as designed). The yields for SiNx thicknesses of SiNx at 110, 130, and 150 nm were 75, 86, and 86%, respectively.

• Membrane Journal
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• v.32 no.5
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• pp.304-313
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• 2022

There is evidence that the presence of active pharmaceutical ingredient (APIs) are a danger for aquatic ecosystems and the human health. The presence of APIs such as tetracycline, an antibiotic, in water causes antimicrobial resistance (AMR) in microorganisms inflicting enormous costs on individuals and society. Membranes embedded with catalysts such as TiO₂ or bismuth based catalysts degrade and separate the organic effluents from wastewater. The photocatalytic activity of the catalysts can be enhanced with noble metal doping and addition of carbonaceous materials and formation of heterojunction with other semiconductors. The recollection of photoctalysts is possible through the immobilization of the photocatalysts in polymeric membranes. In this review, the degradation of antibiotics in water is discussed.

• Journal of Sensor Science and Technology
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• v.26 no.1
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• pp.15-23
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• 2017

In this study, bioelectrical impedance analysis, which has been used to assess an alteration in intracellular fluid (ICF) of the body, was applied to detect intravenous infiltration. The experimental results are described as follows. Firstly, when infiltration occurred, the resistance gradually decreased with time and frequency i.e., the resistance decreased with increasing time, proportional to the amount of infiltrated intravenous (IV) solution. At each frequency, the resistance gradually decreased with time, indicating the IV solution (also blood) accumulated in the extracellular fluid (ECF) (including interstitial fluid). Secondly, the resistance ratio started to increase at infiltration, showing the highest value after 1.4 min of infiltration, and gradually decreased thereafter. Thirdly, the impedance ($Z_C$) of cell membrane decreased significantly (especially at 50 kHz) during infiltration and gradually decreased thereafter. Fourthly, Cole-Cole plot indicated that the positions of (R, $X_C$) shifted toward left owing to infiltration, reflecting the IV solution accumulated in the ECF. The resistance ($R_0$) at zero frequency decreased continuously over time, indicating that it is a vital impedance parameter capable of detecting early infiltration during IV infusion. Finally, the mechanism of the current flowing through the ECF, cell membrane, and ICF in the subcutaneous tissues was analyzed as a function of time before and after infiltration, using an equivalent circuit model of the human cell. In conclusion, it was confirmed that the infiltration could be detected early using these impedance parameters during the infusion of IV solution.

• Transactions of the Korean hydrogen and new energy society
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• v.34 no.3
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• pp.283-291
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• 2023

The physical properties were analyzed for four gas diffusion layers, and gas diffusion electrodes (GDEs) for the cathode of high-temperature polymer electrolyte membrane fuel cell were fabricated through bar coating with three binder to carbon (B/C) ratios. Among them, The GDE from JNT30-A6P showed a significant change in secondary pore volume at a B/C ratio of 0.31, which had the largest pore volume among all GDEs. In the polarization curve, JNT30-A6P GDE showed the best membrane electrode assembly (MEA) performance with a peak power density of 384 mW/cm² at a a B/C ratio of 0.31. From the distribution of relaxation time analysis, the peak 1 corresponding to mass transfer resistance of oxygen reduction reaction (ORR) was significantly reduced in the JNT30-A6P GDE. This is the result that when the binder content decreased, the volume of the secondary pore increased, and the mass transfer resistance of ORR decreased, which played an essential role in the MEA performance.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 1995.06b
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• pp.97-117
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• 1995

Copper resistance in Pseudomonas syringae pv. tomato is determined by copper-resistance operon (cop) on a highly conserved 35 kilobase plasmid. Copper-resistant strains of Pseudomonas syringae containing the cop operon accumulate copper and develop blue clonies on copper-containing media. The protein products of the copper-resistance operon were characterized to provide an understanding of the copper-resistance mechanism and its relationship to copper accumulation. The Cop proteins CopA (72 kDa), CopB (39 kDa), and CopC (12 kDa) were produced only under copper induction. CopA and CopC were periplasmic proteins and CopB was an outer membrane protein. Leader peptide sequences of CopA, CopB, and CopC were confirmed by amino-terminal peptide sequencing. CopA, CopB, and CopC were purified from strain PT23.2, and their copper contents were determined. One molecule of CopA bound 10.9${\pm}$1.2 atoms of copper and one molecule of CopC bound 0.6${\pm}$0.1 atom of copper. P. syringae cells containing copCD or copBCD cloned behind the lac promoter were hypersensitive to copper. The CopD (32 kDa), a probable inner membrane protein, function in copper uptake with CopC. The Cop proteins apparently mediate sequestration of copper outside of the cytoplasm as a copper-resistance mechanism.

• Membrane and Water Treatment
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• v.9 no.5
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• pp.353-361
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• 2018

Fouling characteristics of humic substances on tight ultrafiltration (UF) membrane have been investigated. The tight UF membrane was prepared by blending polysulfone (PSf) in N.N-dimethylacetamide (DMAc) with 25%wt of Polyethylene glycol (PEG400) and 4%wt of acetone. Fouling characteristic of the modified PSf membrane was observed during peat water filtration in different trans-membrane pressure (TMP). It was found that the acetone modified membrane provided 13% increase in TMP during five hours of peat water filtration, where a stable flux was reached within 150 minutes. Meanwhile, the increase of TMP from 10 psig to 30 psig resulted in a fouling resistance enhancement of 60%. Furthermore, based on the fouling analysis, fouling mechanism at the first phase of filtration was attributed to intermediate blocking while the second phase was cake formation.

• Proceedings of the Membrane Society of Korea Conference
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• 2003.07a
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• pp.1-4
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• 2003

LDPE/polystyrene cation exchange membranes were prepared through a monomer-sorption method and UV radiation polymerization. The reaction behaviors in the preparation were investigated. The membranes prepared were characterized in terms of physical and electrochemical properties. The membranes exhibited reasonable properties for an ion-exchange membrane with weight gain (Wr) of above 0.3, electrical resistance of below 1.0 Ω $\textrm{cm}^2$ and ion-exchange capacity of 1.8 meq/g-dry membrane. DSC studies and FE-SEM image revealed the formation of a homogeneous membrane. Both the current-voltage and the chronopotentiometric curves of the membranes indicated that LDPE/polystyrene membranes can be properly used at a high current density, and the surface homogeneity of cation-exchange sites in the membrane was comparable to that in a commercial membrane.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.3
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• pp.523-533
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• 2000

A two-phase anaerobic reactor with submerged membrane system was developed for increasing acidogen concentration and methane recovery. The membrane used was mixed esters of cellulose of $0.5{\mu}m$ pore size and $0.8m^2$ of effective surface area. The methanogenic reactor comprised of UASB (Upflow Anaerobic Sludge Blanket) and AF (Anaerobic Filter). COD removal efficiency was 70~80% and the methane content in the biogas increased up to 90% for the submerged membrane system in the anaerobic reactor. As the cake resistance of membrane caused a serious problem, stainless steal prefilters (40, 53, $63{\mu}m$) and air backwashing methods were applied to minimize the cake resistance effectively. Among the tested prefilters. the $63{\mu}m$ prefilter showed the best performance for reduction of cake resistance and a successful long-tern operation. By cleaning with alkali first and acidic solution later. the permeate flux decreased by long term operation was recovered to 89% of that with a new membrane.

• Journal of Korean Society of Water Science and Technology
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• v.26 no.6
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• pp.61-72
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• 2018

In this study, applicability of the decentralized water supply system were investigated by the high flux evaluation using ceramic membrane with combined pretreatment process. A) filtration process increased the transmembrane pressure of 1.4 kPa and 89.5 kPa on 2 and $5m^3/m^2{\cdot}d$ of filtration flux, respectively, the physical backwashing recovery rate were less than 28.6%. The (B) Coag./Floc. - Sedi. combined process with 4 mg / L of A-PAC showed that the transmembrane pressure increased to within 6 kPa, the physical backwashing recovery rate was over 37.9 % higher than (A) Filtration process. (C) Coag./Floc. combined process showed an increase of transmembrane pressure compared with (B) Coag./Floc. - Sedi. combined process, physical backwashing recovery rate was over 84%. As a result of the membrane fouling analysis using the resistance in series model, the combined pretreatment process showed that the cake resistance (Rc) was more than 92% at membrane filtration flux of $2m^3/m^2{\cdot}d$. In the (C) Coag./Floc. combined process, cake resistance(Rc) was over 86% on high flux conditions. The coagulation floc contained in influent was removed by the membrane, and the cake layer formed with the removed floc was identified as reversible fouling resistance which could be recovered by physical backwashing. The decentralized water supply system, which has the limitation of site area and installation space, is considered to could be operation of high flux of ceramic membrane by applying (C) Coag./Floc. combined process without sedimentation process.