• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1998년도 가을 학술발표회 논문집
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• pp.325-332
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• 1998

The use of air-supported membrane has considerable attention in recent years. There are, however, a number of problems in the behavior of these structures that have not been fully investigated. For example, the problem of local loafing on such membranes has not been analyzed yet. The paper presents an analysis of internal and external potential energy of a spherical air-supported membrane with vertical longitudinal axis, subjected to local loadings. An internal pressure value of the applied load is established at which tile potential of these structures change positive. During such change the loading portion of the membrane comes into work beyond stable state. The mathematical method is used throughout the paper in obtaining solution. For the mathematical modeling, two assumption are used. One is the theta's elimination and the other is the infinite condition. The paper is illustrating the examples of spherical air membrane dome subjected to local load.

• 한국농공학회논문집
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• 제55권2호
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• pp.21-27
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• 2013

The present study explored the way to desalinate seawater for agricultural irrigation using forward osmosis (FO) process using liquid fertilizer as draw solution. FO experiments were performed in a cross flow mode using flat sheet FO membrane. The effect of membrane orientation, flow rate, and draw solution concentration on the performance of forward osmosis was investigated by measuring water flux of forward osmosis membrane. The water flux when the draw solution was placed against the membrane active layer was lower than the water flux when the feed solution was placed against the membrane active layer. This results indicated that the decrease of effective osmotic pressure by dilutive internal concentration polarization was less than that by concentrative internal concentration polarization. Increasing flow rate from 66.7 to 133.1 $cm^3$/min resulted in increase of the water flux when the membrane active layer orient to draw solution and feed solution, respectively. The reduction of resistance to water flow increased water flux at higher flow rate. The water flux of FO membrane increased with increasing draw solution concentration from 10000 to 30000 mg/L. The water flux for $KH_2PO_4$ draw solution was similar to that for commercial fertilizer. Optimization of FO process would contribute to economically desalinate brackish water for agricultural use.

• 상하수도학회지
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• 제30권4호
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• pp.417-425
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• 2016

Desalination is a key technology to overcome water shortage problem in a near future. High energy consumption is an Achilles' heel in desalination technology. Osmotically driven membrane processes like forward osmosis(FO) was introduced to address this energy issue. Characterizing membrane properties such as water permeability(A), salt permeability(B), and the resistance to salt diffusion within the support layer($K_{ICP}$) are very important to predict the performance of scaled-up FO processes. Currently, most of researches reported that the water permeability of FO membrane was measured by reverse osmosis(RO) type test. Permeating direction of RO and FO are different and RO test needs hydraulic pressure so that several problems can be occurred(i.e. membrane deformation, compaction and effect of concentration polarization). This study focuses on measuring water permeability of FO membrane by FO type test results in various experimental conditions. A statistical approach was developed to evaluate the three FO membrane properties(A, B, and $K_{ICP}$) and it predicted test result by the internal and external concentration polarization model.

• 한국공간구조학회논문집
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• 제21권4호
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• pp.49-56
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• 2021

This study aims to develop a form-finding algorithm for a single-layered pneumatic membrane. The initial shape of this pneumatic membrane, which is an air-supported type pneumatic membrane, is to find a state in which a given initial tension and internal pneumatic pressure are in equilibrium. The algorithm developed to satisfy these conditions is that a nonlinear optimization problem based on the force method considering the deformed shape is formulated, and, it's able to find the shape by iteratively repeating the process of obtaining a solution of the governing equations. An computational technique based on the Gauss-Newton method was used as a method for obtaining solutions of nonlinear equations. In order to verify the validity of the proposed form-finding algorithm, a single-curvature pneumatic membrane example and a double-curvature air pneumatic membrane example were adopted, respectively. In the results of these examples, it was possible to well observe the step-by-step convergence process of the shape of the pneumatic membrane, and it was also possible to confirm the change in shape according to the air pressure. In addition, the calculation results of the shape and internal force after deformation due to initial tension, air pressure, and self-weight were obtained.

• 한국전기전자재료학회논문지
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• 제23권7호
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• pp.530-533
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• 2010

The proton exchange membrane fuel cell (PEMFC) holds great promise of clean power. However, in practical applications which use the PEMFC as the power source, the output voltage from the fuel cell undergoes a transient response especially during acceleration and deceleration. This paper presents the relationships between the charge curves of the internal voltage rise, discharge curves of the internal voltage drop, the voltage with a time constant $V_{\tau}$ and finally, the load and time constant $\tau$ of $FC_1$ and $FC_2$, connected both in series and in parallel.

• Molecules and Cells
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• 제37권10호
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• pp.753-758
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• 2014

Sorting nexin 9 (SNX9) is a member of the sorting nexin family of proteins and plays a critical role in clathrinmediated endocytosis. It has a Bin-Amphiphysin-Rvs (BAR) domain which can form a crescent-shaped homodimer structure that induces deformation of the plasma membrane. While other BAR-domain containing proteins such as amphiphysin and endophilin have an amphiphatic helix in front of the BAR domain which plays a critical role in membrane penetration, SNX9 does not. Thus, whether and how SNX9 BAR domain could induce the deformation of the plasma membrane is not clear. The present study identified the internal putative amphiphatic stretch in the $1^{st}$ ${\alpha}$-helix of the SNX9 BAR domain and proved that together with the N-terminal helix ($H_0$) region, this internal putative amphiphatic stretch is critical for inducing membrane tubulation. Therefore, our study shows that SNX9 uses a unique mechanism to induce the tubulation of the plasma membrane which mediates proper membrane deformation during clathrinmediated endocytosis.

• 상하수도학회지
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• 제32권2호
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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.

• 대한한방내과학회지
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• 제18권1호
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• pp.147-155
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• 1997

This study was undertaken to determine whether Salviae-radix (SVR) exraction exerts benefical effect against oxidant-induced inhibition of tetraethylammonium (TEA) uptake which is actively secreted by renal proximal tubules. TEA uptake increased as function of incubation time to 60 min. When renal cortical slices were exposed to 50 mM $H_2O_2$, TEA uptake was significantly inhibited. The inhibition was significantly protected by addition of 0.5% SVR extraction. The benefical effect of SVR was dose-dependent over the concentration range of 0.1-1%; $H_2O_2$ (50 mM)-induced inhibition of TEA uptake was completely protected by 0.5-1% SVR extraction. $H_2O_2$ increased LDH release which was accompanied by an increase in lipid peroxidation in renal cortical slices. These changes were prevented by 0.5% SVR. These results suggest that SVR exerts benefical effect against oxidant-induced impairment of membrane transport function, this effect may be due to by an antioxidant action.

• Archives of Pharmacal Research
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• 제26권1호
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• pp.64-69
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• 2003

To analyze vasopressin-induced $Ca^{2+}$ increase in liver cells, rat hepatocytes were isolated and attached to collagen-coated cover slips. Using fura-2, a $Ca^{2+}$-sensing dye, changes in intracellular $Ca^{2+}$ concentration by vasopressin were monitored. Results in this communication suggested that vasopressin-induced $Ca^{2+}$ increase were composed of both $Ca^{2+}$ release from internal $Ca^{2+}$ stores and influx from the plasma membrane. The $Ca^{2+}$ influx consisted of two distinguishable components. One was dependent on the presence of vasopressin and the other was not. SK＆F96365 blocked vasopressin-induced $Ca^{2+}$ influx in a dose-dependent manner. Vasopressin-induced $Ca^{2+}$ release from internal stores diminished in a primary culture of hepatocytes according to the culture time. However, changes in vasopressin-induced $Ca^{2+}$ influx across the plasma membrane differed from changes in the $Ca^{2+}$ release from internal stores, suggesting two separate signalings from receptor activation to internal stores and to the plasma membrane.

• 한국물환경학회지
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• 제18권2호
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• pp.131-140
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• 2002

Laboratory-scale membrane bioreactor added alum into the anaerobic basin as a flocculant and adsorbent was carried out to find removal efficient of nitrogen and phosphorus components in the mixed liquid and weather or not maintaining the stability for the permeate flux and pressure at various internal recycle conditions. It was found that denitrification efficient of maximum 65% was obtained when the ratio of internal recycle was 3Q. Additionally when the ratio of internal recycle was fixed at 3Q, $BOD_5$ and T-P concentration of permeate was much more reduced compared to not added alum in anaerobic basin but T-N concentration of permeate was relatively increased. In case of added alum as the flocculant and adsorbent in anaerobic basin, the permeate flux was maintained above $10{\ell}/m^2/hr$ but the permeate pressure was relatively higher than alum was not added in anaerobic basin.