• Transactions of the Korean hydrogen and new energy society
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• v.22 no.2
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• pp.184-190
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• 2011

The membrane properties (membrane resistance and ion exchange capacity) of the five types of commercial anion exchange membrane, i.e. IOMAC, AHT, APS, AHA, AFN, were evaluated for the application in the alkaline electrolysis. The membrane resistance decreased in the order; in 1M KOH: AHT>IOMAC>AHA>AFN>APS; in 1M NaOH: AHT>IOMAC>AHA>APS>AFN. The ion exchange capacity decreased in the order: AFN>APS>AHT>AHA>IOMAC. The membrane life was determined from the change of membrane resistance in 1M KOH and NaOH with an increase of soaking time in 20 wt% KOH and 30 wt% NaOH solution. AHA membrane had a good membrane life in 20 wt% NaOH with its unchanged membrane resistance. And, AFN and AHA membrane had a good membrane life in 30 wt% NaOH with its unchanged membrane resistance.

• Membrane and Water Treatment
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• v.9 no.4
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• pp.245-253
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• 2018

The aim of this study is to investigate the membrane fouling in a thermophilic membrane bioreactor (TMBR) operated different sludge retention times (SRTs). For this purpose, TMBR was operated at four different SRTs (10, 30, 60 and 100 days). Specific cake resistance (${\alpha}$), cake resistance, gel resistance, total resistance, MFI (modified fouling index) and FDR (flux decrease ratio) were calculated for all SRTs. It was observed that flux in the membrane increases with rising SRT although the sludge concentrations in the TMBR increased. The steady state flux was found to be 31.78; 34.70; 39.60 and 43.70 LMH ($Liter/m^2/h$) for the SRTs of 10, 30, 60 and 100 days respectively. The concentrations of extracellular polymeric substance (EPS) and soluble microbial product (SMP) decreased with increasing SRT. The membrane fouling rate was higher at shorter SRT and the highest fouling rate appeared at an SRT of 10 d. Both the sludge cake layer and gel layer had contribution to the fouling resistance, but the gel layer resistance value was dominant in all SRTs.

• Journal of Korean Society of Water and Wastewater
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• v.32 no.2
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• pp.77-87
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• 2018

In this study, the effects of operating conditions on the formation of reversible and irreversible fouling were investigated in the filtration using ceramic membrane for water treatment process. The effect of coagulation pretreatment on fouling formation was also evaluated by comparing the performance of membrane filtration both with and without addition of coagulant. A resistance-in-series-model was applied for the analysis of membrane fouling. Total resistance (RT) and internal fouling resistance (Rf) increased in the membrane filtration process without coagulation as membrane flux and feed water concentrations increased. Internal fouling resistance, which was not recovered by physical cleaning, was more than 70% of the total resistance at the range of the membrane flux more than $5m^3/m^2{\cdot}day$. In the combined process with coagulation, the cake layer resistance (Rc) increased to about 30-80% of total resistance. As the cake layer formed by coagulation floc was easily removed by physical cleaning, the recovery rate by physical cleaning was 54~90%. It was confirmed from the results that the combined process was more efficient to recover the filtration performance by physical cleaning due to higher formation ratio of reversible fouling, resulted in the mitigation of the frequency of chemical cleaning.

• Korean Journal of Veterinary Research
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• v.31 no.1
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• pp.33-40
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• 1991

For the observations of both the membrane properties and the excitability on the unfertilized eggs of female mice, changes of the membrane resistance and the membrane potential by hyerpolarizing current stimulation were recorded. As current-voltage relation was linear over the entire range (-180mV~+60mV), membrane resistance($R_m$) was calculated from the amplitude of electrotonic potential to a given stimulus current. Also the presence of anode-break excitation was confirmed. The results were as follows; 1. There was a linear relation between the membrane resistance and resting membrane potential, the expected input resistance was 61. 4M$\Omega$(resting membrane potential was $-18.9{\pm}8.7mV$, mean${\pm}$SD, n=30). 2. Transient depolarization with overshoot was generated just after hyperpolarizing current stimulus and showed the dependency of stimulus duration. 3. Transient depolarization lasted over 30ms, amplitude of these depolarization was increased by high $Ca^{{+}{+}}$(20mM) and inhibited by $Ca^{{+}{+}}$-antagonist, $Mn^{{+}{+}}$. 4. From the above results, it was suggested that the unfertilized mouse egg showed the characteristics of the excitable cell.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.05c
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• pp.89-97
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• 2009

As landscaping building roofs and concrete structures increase gradually for low carbon green growth policy of government, But waterproofing membranes of those structures are effecting by root penetration of landscape plant. 80, we progressed study about test method for fast evaluating root resistance of waterproofing materials jointly with Tokyo Institute of Technology. The result of the study is as follows: (1) The penetrating load of the needle at the displacement speed of 1mm/min was measured for various membrane to basis and lap joints of membrane, the load force was $3{\sim}50$ N by material variously. (2) According to the test method of deriving rhizomes of bamboo grass to basis and lap joints of membrane, there were no penetrated membrane until present, but need persistent observation. (3) Test method of deriving rhizomes of bamboo grass to basis and lap joints of membrane can shorten from period of 2 years to 1 year for testing. Because rhizomes of bamboo grass can grow from May to September, test is possible in same period.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.1
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• pp.1-8
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• 2016

Temperature correction trans-membrane pressure (TC-TMP) is frequently used as a fouling index in membrane water treatment plants. TC-TMP equation is derived based on an assumption that the total membrane resistance (i.e. the sum of the intrinsic membrane resistance and fouling resistance) is not affected by temperature. This work verified the validity of this assumption using microfiltration (MF) and ultrafiltration (UF) membranes with and without fouling. The foulants used in the work were kaolin (inorganic) and humic acid (organic). The intrinsic resistances of MF and UF membranes remains at constant values regardless of temperature change. When the same amount of foulants were accumulated on the membrane, inorganic fouling resistance with kaolin was constant regardless of temperature change while organic fouling resistance with humic acid decreased at higher temperatures, which means that TC-TMP cannot be used as a fouling index when organic fouling occurs in a real field application. Since TC-TMP underestimates the amount of fouling at higher temperatures, more attention should be necessary in the operation of membrane water treatment plant in a hotter season like summer.

• Korean Membrane Journal
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• v.5 no.1
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• pp.31-35
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• 2003

The permeation characteristics of the wastewater containing Si fine particles were examined by ultrafiltration using the polyolefin tubular membrane module. Flux with time was due to the growth of Si cake deposited on the membrane surface and the pore plugging by fine particles. The rate of flux decline in the initial stage increased with the trans-membrane pressure. The pore blocking resistance was the dominant resistance at the initial period of filtration and the cake resistance began to dominate with the initial pore blocking resistance. The larger pores compared with the fine particles, the more the membrane pores could be blocked by the fine particles. Before and after treatment, the distribution of particle size was shifted toward to the left. Then, the average size of fine particles in the permeate was 20 nm.

• Journal of Environmental Science International
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• v.25 no.6
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• pp.817-827
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• 2016

The resistance in series model has been frequently used for determination of various filtration resistance to correctly understand the membrane fouling behaviour in MBR (membrane bio-reactor) for wastewater treatment. The cake layer resistance ($R_c$) which is commonly determined by calculation of flux dataset that are obtained empirically before and after removing the cake layer on membrane surface. However, the calculated Rc values are very dependent on the cleaning methods adapted for removal of cake layer. This study investigated how the various cleaning options affect $R_c$. Seven different cleaning methods were employed: i) ultrasonication (100 W, 10 min), ii) ultrasonication (200 W, 60 min), iii) ultrasonication (400 W, 120 min), iv) water rinsing in a shaker (100 rpm, 10 min), v) water rinsing in a shaker (300 rpm, 60 min), vi) water rinsing, vii) sponge scrubbing. For the hydrophilic PES membrane, the cake layer removal efficiencies ranged from 64% to 10%, indicating that the removal of cake layer was highly dependent on the cleaning options. For the hydrophobic PVDF membrane, the cake layer removal efficiencies ranged from 79% to 97%. Consequently, a standardized method for cake layer removal to determine cake resistance ($R_c$) is needed for correct interpretation of the fouling phenomena.

• Membrane Journal
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• v.15 no.4
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• pp.320-329
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• 2005

Polyamide membrane degradation by chlorine has been studied to improve membrane durability. In this study, it was found that the salt rejection was reduced rapidly and flux of the membrane was increased slowly far membrane treated under chlorine condition. In order to improve resistance to chlorine of the polyamide reverse osmosis membrane, fluorine-containing silane coupling agent (FSCA) was introduced to surface modification. Surface properties and chlorine resistance of silane modified membrane were compared with virgin membrane. It was found that the surface of silane modified membrane has dense structure according to FSCA concentration increasing. The results of surface analysis suggest that FSCA retrieved a severe change in the hydrophobicity and surface roughness. In addition, it appears that FSCA can enhance chlorine resistance due to the interaction of such substance with free radical chlorine.

• Membrane and Water Treatment
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• v.13 no.4
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• pp.191-199
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• 2022

In industrial production, the development of traditional polyamide nanofiltration (NF) membrane was limited due to its poor oxidation resistance, complex preparation process and high cost. In this study, a composite NF membrane with high flux, high separation performance, high oxidation resistance and simple process preparation was prepared by the method of dilute solution dip coating. And the sulfonated polysulfone was used for dip coating. The results indicated that the concentration of glycerin, the pore size of the based membrane, the composition of the coating solution, and the post-treatment process had important effects on the structure and performance of the composite NF membrane. The composite NF membrane prepared without glycerol protecting based membrane had a low flux, when the concentration of glycerin increased from 5% to 15%, the pure water flux of the composite NF membrane increased from 46.4 LMH to 108.2 LMH, and the salt rejection rate did not change much. By optimizing the coating system, the rejection rate of Na₂SO₄ and PEG1000 was higher than 90%, the pure water flux was higher than 40 LMH (60psi), and it can withstand 20,000 ppm.h NaClO solution cleaning. When the post treatment processes was adjusted, the salt rejection rate of NaCl solution (250 ppm) reached 45.5%, and the flux reached 62.2 LMH.