• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.435-438
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• 2002

The permeate flux was lower when PAC was added compared to without PAC system. It can be concluded that PAC is cause of membrane fouling. The effect of flow volume was found not significant for the three samples. But it was shown high rejection rate due to adsorption of organic matter to PAC in the case of adding PAC.

• Korean Chemical Engineering Research
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• v.54 no.5
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• pp.598-605
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• 2016

V-Cr-Y alloy is a material for hydrogen separation membrane possessing high transmittance and selectivity. In order to increase the rate of hydrogen permeation flux through the membrane, V-Cr-Y thin film was prepared using a sputtering technique and was investigated focusing on its basic properties. Thin film was deposited on a silicon wafer using a target including V (89.8%), Cr (10.0%) and Y(0.2%), and results of EDS analysis confirm that the ratio of metal in thin film agrees with that in the target. Higher sputtering temperature and power resulted in more rapid growth rate of the thin film and larger size of the crystals, and denser and finer crystal structure was observed when lower pressure was applied. An optimal sputtering condition was found with RF, 2mTorr, 300W and ambient temperature, and a suitable V-Cr-Y thin film for hydrogen separation was obtained upon heat treatment of the thin film prepared in this way.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.2
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• pp.234-238
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• 2008

Coarse pore filter could be an alternative of membrane for solid-liquid separation in an activated sludge reactor because of inexpensive cost of the filter material and high flux at low filtration pressure. However such filter module has much less specific filtration area compared to the membrane. Therefore a certain effort is required to increase the specific filtration area in the module design of such coarse pore filter for solid-liquid separation in an activated sludge reactor. In this study, tubular type coarse pore filter was designed at various diameter and configuration. The filtration performance was investigated to separate solid in the activated sludge reactor for domestic wastewater treatment. Tubular type coarse pore filter module could be successfully applicable to solid separation in the activated sludge reactor. The design parameters were the tube diameter of 10mm and vertical installation. Smaller diameter of the tube caused faster increase of the filtration pressure because of the hydraulic head loss in the tube channel.

• Membrane Journal
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• v.17 no.3
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• pp.184-190
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• 2007

This study reports on the pervaporation separation of a volatile organic compound(VOC), dichloromethane(DCM) from water using fluorinated copolysiloxaneimide membranes. The copolysiloxaneimide membranes were prepared from 4,4'-(hexafluoroisopropylidene)diphthalic anhydride(6FDA) and two diamines(polysiloxane diamine(SIDA), 2-(perfluorohexyl)ethyl-3,5-diaminobenzene(PFDAB)). By varying the ratio of flexible polysiloxane diamine(SIDA)/rigid fluorinated aromatic diamine(PFDAB) from 0/100 to 100/0 mol%, five copolysiloxaneimide membranes were prepared success- fully. The pervaporation properties of DCM/water were examined in terms of two diamine monomer ratio at room temperature and the feed composition of 0.05 wt% in water. It was found that the increase in SIDA content led to high permeation flux and pervaporation selectivity towards DCM by the enhanced sorption/sorption selectivity and diffusion coefficient/diffusion selectivity due to the increased hydrophobicity and fractional free volume.

• Applied Chemistry for Engineering
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• v.8 no.6
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• pp.945-953
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• 1997

Aromatic polyetherimide membranes were prepared by dry/wet phase inversion method and investigated regarding the pervaporation characteristic of water-alcohol mixtures by using the permselective property of imide group and the structure modification of skin layer of the membrane. The membrane selectivity increased with the reaction time of surface-modification, to some extent, and the density of top layer tends to increases with increasing the reaction time. In the case of dense membrane, the separation factor was 160 and 2000 for 90wt% ethanol mixture and 90wt% isopropanol solution, respectively, which implies that aromatic polyetherimide has a high permselectivity. The temperature dependence of permeation flux seems to follow an Arrhenius type at the temperature range of ($40^{\circ}C-70^{\circ}C$).

• KOREAN JOURNAL OF CROP SCIENCE
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• v.52 no.2
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• pp.213-219
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• 2007

It has been well established that aluminum (Al) inhibits root tip growth rapidly in acid soil. We report the correlation between Al induced growth inhibition and impaired $H^+-flux$ in mung bean (Vigna radiate L. cv. Kumsung). The root growth inhibition was dependent on Al concentration (0, 10, 25, 50, $100{\mu}M$) and exposure time (12 and 24 h). Using Hematoxylin staining, it was observed that the root damage was occurred preferentially in regions with high Al accumulation. Using the pH indicator, it was shown that the surface pH of root tip was strongly alkalized in the control whereas changed only slightly in the $50{\mu}M$ Al-treated root. The $H^+-ATPase$ activity of plasma membrane vesicles was inhibited by 56% in the Al-treated roots compared to control root. Decrease in the amount of the plasma membrane $H^+-ATPase$ (100 kDa) translation in the plant roots under Al stress was demonstrated by Western blot analysis. These results indicate that the dynamics of $H^+-flux$ across the root tip play an important role in root growth under Al stress.

• Transactions on Electrical and Electronic Materials
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• v.17 no.2
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• pp.57-68
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• 2016

In this study, we present the modern hybrid system based power generation for electric vehicle applications. We describe the hybrid structure of modified current source based DC - DC converters used to extract the maximum power from Photovoltaic (PV) and Fuel Cell system. Due to reduced dc-link capacitor requirement and higher reliability, the current source inverters (CSI) better compared to the voltage source based inverter. The novel control strategy includes Distributed Maximum Power Point Tracking (DMPPT) for photovoltaic (PV) and fuel cell power generation system. The proposed DC - DC converters have been analyzed in both buck and boost mode of operation under duty cycle 0.5>d, 0.5<d<1 and 0.5<d for capable electric vehicle applications. The proposed topology benefits include one common DC-AC inverter that interposes the generated power to supply the charge for the sharing of load in a system of hybrid supply with photovoltaic panels and fuel cell PEM. An improved control of Direct Torque and Flux Control (DTFC) based induction motor fed by current source converters for electric vehicle.In order to achieve better performance in terms of speed, power and miles per gallon for the expert, to accepting high regenerative braking current as well as persistent high dynamics driving performance is required. A simulation model for the hybrid power generation system based electric vehicle has been developed by using MATLAB/Simulink. The Direct Torque and Flux Control (DTFC) is planned using Xilinx ISE software tool in addition to a Modelsim 6.3 software tool that is used for simulation purposes. The FPGA based pulse generation is used to control the induction motor for electric vehicle applications. FPGA has been implemented, in order to verify the minimal error between the simulation results of MATLAB/Simulink and experimental results.

• Membrane Journal
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• v.21 no.2
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• pp.127-140
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• 2011

The effects of $TiO_2$ photocatalyst coating bead concentration, water-back-flushing period (FT), and back-flushing time (BT) were investigated in hybrid process of ceramic ultrafiltration and photocatalyst for advanced drinking water treatment in this study. Photocatalyst coating bead concentration was changed in the range of 10~40 g/L, FT in 2~10 min and BT in 6~30 sec. Then, we observed the effects on resistance of membrane fouling $(R_f)$, permeate flux (J) and total permeate volume $(V_{\Upsilon})$ during total filtration time of 180 min. As decreasing photocatalyst coating bead concentration, $R_f$ increased and J decreased. $V_{\Upsilon}$ was the highest value of 8.85 L at 40 g/L of photocatalyst coating bead concentration. At FT change experiment, $R_f$ decreased and J increased as decreasing FT. Then $R_f$ decreased and J increased according to increasing BT at BT change experiment. Because at NBF (no back-flushing) dramatic membrane fouling reduced membrane pore size, turbid and dissolved organic matters ($UV_{254}$ absorbance) could be removed efficiently. Therefore, treatment efficiencies of turbidity and dissolved organic matters were the highest at NBF. Then by cleaning effect of photocatalyst coating bead, the treatment efficiencies of turbidity and dissolved organic matters increased as decreasing FT and increasing BT.

• Membrane Journal
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• v.21 no.2
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• pp.201-211
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• 2011

The effects of humic acid (HA), photo-oxidation and adsorption were investigated in hybrid process of ceramic ultrafiltration and photocatalyst for drinking water treatment. UF, photocatalyst, and UV radiation processes were investigated in viewpoints of membrane fouling resistance $(R_f)$, permeate flux (J), and total penneate volume $(V_{\Upsilon})$ at 2 and 4 mg/L of HA respectively. As decreasing HA, $R_f$ decreased dramatically and J increased, and finally $V_{\Upsilon}$ was the highest at 2 mg/L HA. Average treatment efficiencies of turbidity decreased as increasing HA, but treatment efficiency of HA was the highest at 4 mg/L HA. It was because most of HA was removed by membrane and some HA passing through the membrane was adsorbed or photo-oxidized by photocatalyst at low HA, and therefore treated water quality was almost same at 2 and 4 mg/L HA, but feed water quality was higher at 4 mg/L. At effect experiment of photo-oxidation and adsorption, J of UF + $TiO_2$ + UV process was maintained at the highest, and ultimately $(V_{\Upsilon})$ after 180 minutes' operation was the highest. As results of comparing the treatment efficiencies of turbidity and HA, photocatalyst adsorption had more important role than photo-oxidation when HA increased from 2 to 4 mg/L.

• Membrane Journal
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• v.9 no.3
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• pp.157-162
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• 1999

In the crosslining reaction of poly(vinyl alcohoJ)(PVA) with sulfur-succinic acid which had been established in our previous work, reaction temperature, 15$0^{\circ}C$, was so high to collapse the pore struc¬tures in support membrane for the preparation of composite membrane. Therefore, the efforts have been focused on lowering of the reaction temperature to 100$^{\circ}$C by using a catalysis, HC!. The newly established crosslinking reaction was characterized through the analysis of the chemical and thermal properties. From these results, the optimum conditions for the membrane preparation couId be drawn as followings : (i) reac¬tion temperature, 100 $^{\circ}C$,(ii) reaction time, 90 min, (iii) the concentration of the catalysis (HCD, 1.5%. Com¬posite membranes were fabricated by coating a casting solution containing PYA, sulfur-succinic acid and HCl on a support membrane followed by crosslinking it at 10$0^{\circ}C$. The resulting membranes were applied to the pervaporation separation of methyl-tert-butyl ether(MTBE)/methanol (MeOH) mixtures at 30, 40, and 5O$^{\circ}C$. The flux of 5.09 g/$m^2$hr at 5O$^{\circ}C$ and the highest separation factor of 1622 were obtained, respectively.