• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.459-465
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• 2001

The work was initiated to investigate the electrokinetic properties of a MF membrane using streaming potential measurement when oil emulsion was separated. The original and the surface modified PP membrane were examined by using flux and streaming potentials for the characterization of fouling phenomena of the PP membrane. The membrane surface was modified by a radiation grafting technique. The streaming potentials of the PP membranes were varied the charge distribution modifying by changing the pH, ionic strength, and concentrations the surfactants in oil emulsion. The shiftness to the more positive values of isoelectric point of the PP membrane was significant especially in the presence of surfactants or the surface modification.

• 멤브레인
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• 제17권4호
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• pp.345-351
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• 2007

본 연구에서는 선택적 Gas-Liquid Contactor의 성능을 향상시키기 위하여 polyethersulfone(PES), polysulfone(PSf), polyvinylidenefluoride (PVDF) 등의 막에 $F_2$ gas를 이용하여 표면개질하였다. 표면개질된 막의 특성을 알아보기 위해 SEM, 표면접촉각, XPS, 물 투과 최소 압력 실험을 수행하였다. SEM 측정으로부터 막의 표면형태를 살펴본 결과 불소처리 시간이 증가함에 따라 막 표면의 roughness가 증가함을 알 수 있었다. 표면불소화한 막 표면에 $-CF_2$, $-CF_3$의 perfluoro group이 화학적으로 결합되어 막의 소수성이 증가된 것으로 나타났다. 또한 표면접촉각 및 물 투과 최소 압력 실험으로부터 표면불소화 처리시간이 증가함에 따라 측정값이 증가하여 막의 특성이 향상됨을 알 수 있었다.

• Membrane and Water Treatment
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• 제6권5호
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• pp.411-422
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• 2015

Membrane modification by different concentrations of acrylic acid has been described. Grafting of acrylic acid to the surface of a polypropylene membrane was obtained by a Fenton-type reaction. Membrane permeability seemed to have been dependent on the value of pH in the solution. To explain tendency, a simple theoretical model was developed. The model incorporates explicitly statistical conformations of a polyacid chain grafted onto the pore surface. The charged capillary model with a varying diameter for porous membranes was then used to evaluate the permeability of the membrane. It has been shown both theoretically and experimentally that the permeability of a grafted membrane depends on the pH of the solution.

• Membrane and Water Treatment
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• 제11권3호
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• pp.231-235
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• 2020

Industrialization and modern developments have led to an influx of toxic heavy metals into the aquatic environment, and the accumulation of heavy metals has serious adverse effects on humans. Among the various heavy metal treatment methods, adsorption is very useful and frequently used. Plastic materials, such as polypropylene and polyethylene, have been widely used as filter media due to their mechanical and chemical stability. However, the surface of plastic material is inert and therefore the adsorption capability of heavy metals is very limited. In this study, granular media and fiber media composed of polypropylene and polyethylene are used, and the surface modification was conducted in order to increase adsorption capability toward heavy metals. Oxygen plasma generated hydroxyl groups on the surface of the media to activate the surface, and then acrylic acid was synthesized on the surface. The grafted carboxyl group was confirmed by FT-IR and SEM. Heavy metal adsorption capability of pristine and surface modified adsorbents was also evaluated. Overall, heavy metal adsorption capability was increased by surface modification due to electrostatic interaction between the carboxyl groups and heavy metal ions. Fibrous PP/PE showed lower improvement compared to granular PP media because pore blockage occurred by the surface modification step, thereby inhibiting mass transfer.

• Journal of Biosystems Engineering
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• 제24권6호
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• pp.473-478
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• 1999

Recently, it is necessary fir surface materials to be low cost and to keep well endurable and wear in machinery field. Since most good materials with endurance and wear are expensive, they are being studied hard to modify to surface materials with endurance and wear, which overlay with the surface membrane completely. One of them is PTA(Plasma Transferred Arc Overlaying Process) method, which gets into the spotlight. It is thought to be an optimum method, since this method of overlays properly materials with about 3∼5cm surface membrane. It is necessity for the modified materials with endurance and wear to improve within the agricultural environment. Therefore, this research was used the PTA method to endure and wear a material. This method proved to be a reliable method for overlaying the membrane on the materials of an economical agricultural machinery.

• Membrane and Water Treatment
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• 제6권5호
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• pp.351-363
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• 2015

To increase the surface hydrophilicity of PVDF membranes, in this paper, an electric enhancing method was adopted to treat PVDF nascent membranes during the phase inversion process. It was found that when PEG 600 was taken as the additive, the surface water contact angle of the PVDF membrane treated under 2 kV electric field was decreased from $84.0^{\circ}$ to $65.7^{\circ}$. The reason for the surface elements change of the PVDF membranes prepared under the electric field was analyzed in detail with the dielectric parameters of the polymer dope solutions. Results from BSA adsorption experiment showed that the antifouling ability of the external electric field-treated membranes was distinctly enhanced when compared with that of the untreated membranes. The amount of BSA adsorbed by the treated membranes was lower by 38-43%. Compared with the common chemical reaction methods to synthesize hydrophilic additives or membrane materials, the electric field-assisted processing method did not involve any additional chemical synthesis process and it was capable of realizing better hydrophilicity.

• 한국물환경학회지
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• 제38권3호
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• pp.143-149
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• 2022

Membrane distillation (MD) has emerged as a sustainable desalination technology to solve the water and energy problems faced by the modern society. In particular, the surface wetting properties of the membrane have been recognized as a key parameter to determine the performance of the MD system. In this study, a novel surface modification technique was developed to induce a Janus-type hydrophilic/hydrophobic layer on the membrane surface. The hydrophilic layer was created on a porous PVDF membrane by vapor phase polymerization of the pyrrole monomer, forming a thin coating of polypyrrole on the membrane walls. A rigid polymeric coating layer was created without compromising the membrane porosity. The hydrophilic coating was then followed by the in-situ growth of siloxane nanoparticles, where the condensation of organosilane provided quick loading of hydrophobic layers on the membrane surface. The composite layers of dual coatings allowed systematic control of the surface wettability of porous membranes. By the virtue of the photothermal property of the hydrophilic polypyrrole layer, the desalination performance of the coated membrane was tested in a solar MD system. The wetting properties of the dual-layer were further evaluated in a direct-contact MD module, exploring the potential of the Janus membrane structure for effective and low-energy desalination.

• Macromolecular Research
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• 제12권6호
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• pp.553-558
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• 2004

An ultrafiltration membrane (polyethersulfone, PM 10) was surface-modified by treating it with low-tem­perature plasmas of oxygen, acrylic acid (AA), acetylene, diaminocyolohexane (DACH), and hexamethyldisiloxane (HMDSO). The effects that these modifications have on the filtration efficiency of a membrane in waste water treat­ment were investigated. The oxygen, AA, and DACH plasma-treated membranes became more hydrophilic. The water contact angles ranged from < $10^{\circ}\;to\;55^{\circ}$ depending on the type of plasma and the treatment conditions. The oxygen plasma-treated membranes displayed a higher initial flux $(312-429\%),$ but lower rejection $(6-91\%),$ than did an untreated membrane. The AA plasma-treated membranes displayed lower or higher initial flux $(42-156\%),$ depending upon the treatment conditions, but higher rejection $(224-295\%)$ in all cases. The DACH plasma-treated membranes displayed lower initial flux. All of them, especially the AA plasma-treated membrane, displayed improved fouling resistance with either a slower or no flux decline. Acetylene and HMDSO plasma-treated membranes became more hydrophobic and displayed both lower initial flux and lower fouling resistance.

• 한국막학회:학술대회논문집
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• 한국막학회 1998년도 춘계 총회 및 학술발표회
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• pp.99-101
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• 1998

1. Introduction : The conventional grafting polymerization technique requires chemically reactive groups on the surface as well as on the polymer chains. For this reason, a series of prefunctionalization steps are necessary for covalent grafting. The surface prefunctionalizational technique for grafting can be used to ionization radiation, UV, plasma, ion beam or chemical initiators. Of these techniques, radiation method is one of the useful methods because of uniform and rapid creation of active radical sites without catalytic contamination in grafted samples. If the diffusion of monomer into polymer is large enough to come to the inside of polymer substrate, a homogeneous and uniform grafting reaction can be carried out throughout the whole polymer substrate. Radiation-induced grafting method may attach specific functional moieties to a polymeric substrate, such as preirradiation and simultaneous irradiation. The former is irradiated at backbone polymer in vacuum or nitrogen gas and air, and then subsequent monomer grafting by trapped or peroxy radicals, while the latter is irradiated at backbone polymer in the presence of the monomer. Therefore, radiation-induced polymerization can be used to modification of the chemical and physical properties of the polymeric materials and has attracted considerable interest because it imparts desirable properties such as blood compatibility. membrane quality, ion excahnge, dyeability, protein adsorption, and immobilization of bioactive materials. Synthesizing biocompatible materials by radiation method such as preirradiation or simultaneous irradiation has often used $\gamma$-rays to graft hydrophilic monomers onto hydrophobic polymer substrates. In this work, in attempt to produce surfaces that show low levels of anti-fouling of bovine serum albumin(BSA) solutions, hydroxyethyl methacrylate(HEMA) was grafted polypropylene membrane surfaces by preirradiation technique. The anti-fouling effect of the polypropylene membrane after grafting was examined by permeation BSA solution.

• 한국가시화정보학회지
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• 제19권1호
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• pp.50-56
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• 2021

With the advances in recent nanotechnology, mass transport phenomena have been receiving large attention both in academic researches and industrial applications. Nonetheless, it is not clearly determined which parameters are dominant at nanoscale mass transport. Especially, membrane is a kind of technology that use a selective separation to secure fresh water. The development of great separation membrane and membrane-based separation system is an important way to solve existing water resource problems. In this study, glass fiber-based membranes which are treated by graphene oxide (GO), poly-styrene sulfonate (GOP) and sodium dodecyl sulfate (GPS) were fabricated. Mass transport parameters were investigated in terms of material-specific and structure-specific dominance. The 3D structural information of GO, GOP, and GPS was obtained by using synchrotron X-ray nano tomography. In addition, electrostatic characteristic and water absorption rate of the membranes were investigated. As a result, we calculated internal structural information using Tomadakis-Sotrichos model, and we found that manipulation of surface characteristics can improve spacer arm effect, which means enhancement of water permeability by control length of ligand and surface charge functionality of the membrane.