• Wind and Structures
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• v.19 no.1
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• pp.35-58
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• 2014

A numerical simultaneous solution involving a linear elastic model was applied to study the fluid-structure interaction (FSI) of membrane structures under wind actions, i.e., formulating the fluid-structure system with a single equation system and solving it simultaneously. The linear elastic model was applied to managing the data transfer at the fluid and structure interface. The monolithic equation of the FSI system was formulated by means of variational forms of equations for the fluid, structure and linear elastic model, and was solved by the Newton-Raphson method. Computation procedures of the proposed simultaneous solution are presented. It was applied to computation of flow around an elastic cylinder and a typical FSI problem to verify the validity and accuracy of the method. Then fluid-structure interaction analyses of a saddle membrane structure under wind actions for three typical cases were performed with the method. Wind pressure, wind-induced responses, displacement power spectra, aerodynamic damping and added mass of the membrane structure were computed and analyzed.

• Proceedings of the Membrane Society of Korea Conference
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• 2001.07a
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• pp.155-162
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• 2001

Advanced drinking water production systems, which not only good quality product water, but also provide easy management and mainenance of facilities, and operate on a smaller site area, have been expected to be developed for some time. We are going ahead with a program to deveop an advanced drinking water production system, using immersed membrane filtration combined with biological activated carbon, to meet the need described above. The demonstration plant tests been conducted with surface water from the Yodo-river since Dec. 1998 to measure treatment performance, reliability, and controllability of the system. The quality of product water has consistently remained at a very high level for about 2 years under controlled conditions. Results showed that the re-circulation granular biological activated carbon could suppress the increase of membrane pressure difference and promote a reduction of dissolved organic matter. (This work has been conducted along the ACT21 Programs.)

• Membrane Journal
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• v.16 no.3
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• pp.213-220
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• 2006

Microfiltration and Nanofiltration membrane were prepared and properties of the membrane system were studied for the application of desaltingfrefiningiconcentrating process of dye production. The membrane system improved the quality of dye produce and productivity was enhanced due to reduction of processing steps and material cost. Membrane and pressure type membrane element in various dye concentration for using desaltingirefiningiconcentrating of dye processing were investigated.

• Journal of Korean Society on Water Environment
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• v.28 no.2
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• pp.292-299
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• 2012

The objective of this study is to develop a novel method for evaluating forward osmosis (FO) membrane performances using a non-pressurized FO system. Basic membrane performance parameters including water (A) and solute (B) permeability coefficients and unique parameter for FO membrane such as the support layer structural parameter (S) were determined in two FO modes (i.e., active layer faces feed solution (AL-FS) and active layer faces draw solution (AL-DS)). Futhermore, these parameters were compared with those determined in a pressurized reverse osmosis (RO) system. Theoretical water flux was calculated by employing these parameters to a model that accounts for the effects of both internal and external concentration polarization. Water flux from FO experiment was compared to theoretical water fluxes for assessing the reliability of those parameters determined in three different operation modes (i.e., AL-FS FO, AL-DS FO, and RO modes). It is demonstrated that FO membrane performance parameters can be accurately measured in non-pressurized FO mode. Specifically, membrane performance parameters determined in AL-DS FO mode most accurately predict FO water flux. This implies that the evaluation of FO membrane performances should be performed in non-pressurized FO mode, which can prevent membrane compaction and/or defect and more precisely reflect FO operation conditions.

• Membrane Journal
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• v.23 no.3
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• pp.204-210
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• 2013

Recently, many applications with grapheneoxide (GO) have been reported. But GO membrane for water treatment has not been developed. In this study we prepared polyvinylidene difluoride (PVdF) nanofiber/GO hybrid membrane (FG) for the microfiltration application. The PVdF substrate membrane was prepared by using the electrospinning method with a solution of PVdF in N,N-dimethylacetamide (DMAc) and acetone. GO sheets used in this study were prepared by modified Hummer's method. The PVdF/GO hybrid membrane was finally prepared by spraying the GO solution dispersed in ethanol on the PVdF nanofiber. The successfully prepared FG was thoroughly examined by SEM, Raman, contact angle, porometer and UTM, and water-flux was measured with designed cell (Dead-End Cell). From the contact angle results, it was found that the surface of FG membrane was reformed by hydrophilic property and the water permeability was increased about 2.5 times than that of the nascent PVdF membrane, indicating the possible alternative of the commercial MF membrane.

• Journal of Advanced Research in Ocean Engineering
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• v.3 no.3
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• pp.112-124
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• 2017

As an LNG carrier preserves and transports liquefied natural gas under minus $163^{\circ}C$, the cargo tank has to have sufficient hull strength against not only the wave loads but also against loads caused by loading and unloading and thermal expansion to keep the LNG safely. The main insulation types for a CCS are No.96 and Mark III from GTT for the membrane LNG carrier. Particularly, the invar membrane plate in No.96 is very thin and its connections could experience high local stresses owing to such dynamic loads. Therefore, it should be verified whether those connections have sufficient fatigue lives for the purpose of operation and maintenance. This research aims at performing fatigue analysis with 0.1 fatigue damage criteria for 40 years of design life to support new membrane CCS development using proper S-N curves and the associated finite element modeling technique for each connection and then propose a reasonable design methodology.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.745-748
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• 2000

Anaerobic digester coupled with hollow fiber membrane unit. Treatment of starch waste with anaerobic digester-membrane system was studied. $0.17\;m^2$ area of hollow fiber membrane unit of known pore size was immersed into laboratory-scale anaerobic digestion system. The gas production was about $0.74\;m^3/kg$ COD treated. The COD removal efficient was about 80-95% depending on the hydraulic retention time. Crossflow ultrafiltration as Post treatment to anaerobic filter. The study conducted with different membrane pore size indicated that membrane with 1,000,000 molecular weight cut-off size gave a higher COD removal efficiency in the range of 83-87% while giving a study flux of $120-130\;L/m^2\;{\cdot}\;h$. A study was conducted to see the long term clogging effect of membrane also.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.420-425
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• 2001

Theoretical analysis of noise reduction by a membrane-duct system is presented. When acorn waves propagate in the membrane-duct, the membrane is also excited and its motion is coup with interior medium. It has been shown that propagating waves with supersonic wave speed exist beyond a certain critical frequency that is determined from the mass ratio of the me and the fluid. Also found are subsonic waves which couple strongly wi th the membrane a provide a powerful mechanism of energy dissipation. Existence of an exterior medium alter dispersion characteristics. It provides additional mass loading and reduces the subsort speed further. The effect of mean flow speed on dispersion characteristics is also consider results show that the membrane-duct system can be applied to diminish and absorb 1 frequency noise in duct instead of passive muffler, such as a simple expansion chamber absorption material.

• 한국공간정보시스템학회:학술대회논문집
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• 2004.05a
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• pp.222-229
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• 2004

This study purports to analyze equally stressed surfaces in tension-membrane structures through a geometrically nonlinear approach. It adopts the formulation of a 4-node quadrilateral isoparametric plane stress element considering the orthotropic characteristic of membrane textures. Tension structures, which include cables and tension membranes, such as a cable dome initially exhibit unstable conditions because no initial internal stiffness such as bending stiffness is present. Such a structural system requires prestressing to the tension members to attain a stable state. A tension-membrane structure retains a stable three dimensional curved surface as a structural shape. This analytical process for finding the geometry is referred to as Shape Finding Analysis. In order to assess the validity of this study, we examine equally stressed surfaces of saddle and catenary shape shell structures and carry out pertinent stress analyses

• 한국신재생에너지학회:학술대회논문집
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• 2008.10a
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• pp.6-9
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• 2008

The efficiency and life time of the proton exchange membrane (PEM) fuel cell system is critically changed with its humidity which should be maintained properly during dynamic operation. Membrane humidifier is required to regulate proper humidity level for the design point of the PEMFC system. In this study, we presented the performance of the cylindrical membrane humidifier which is operated as water-to-gas. Dry air pressure, liquid water flow temperature, and air flow rate were chosen as the operating parameters. Humidity level is expressed with dew point.