• Membrane Journal
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• v.24 no.1
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• pp.69-77
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• 2014

To prepare the hollow fiber nanofiltration composite membranes, the poly(vinylidene fluoride) (PVDF) membrane was hydrophilized with $K_2Cr_2OH$ and $KMnO_4$ aqueous solutions. And then the composite membrane was synthesized on that membrane surfaces using interfacial polymerization with piperazine (PIP) and trimesoyl chloride (TMC). The resulting membranes were characterized in terms of the rejection and flux for NaCl, $CaSO_4$, $MgCl_2$ 100 ppm solution and 300 ppm of NaCl and $CaSO_4$ mixed solution by varying the coating time, drying time, and the concentration of the coating materials. As a result, the higher rejections were shown for $K_2Cr_2OH$ solutionas a hydrophilization material, and the flux was enhanced while the rejection reduced as the hydrophilization time is longer. Also, the rejection increased and the flux reduced as the concentrations of triethyl amine (TEA) and sodium lauryl sulfate (SLS) were higher. Typically, the rejection 50% and flux 40 LMH for NaCl 100 ppm solution, and the rejection 55% and flux 48 LMH for $CaSO_4$ 100 ppm solution were obtained for the PVDF hollow fiber composite membrane prepared with the conditions of PIP 2 wt% (Triethyl amine (TEA) 7 wt%, SLS 20 wt% mixed solution against PIP concentration) and TMC 0.1 wt%.

• Transactions on Electrical and Electronic Materials
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• v.16 no.2
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• pp.103-105
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• 2015

Effect of silicon doping into ZnSnO systems was investigated using solution process. Addition of silicon was used to suppress oxygen vacancy generation. The transfer characteristics of the device showed threshold voltage shift toward the positive direction with increasing Si content due to the high binding energy of silicon atoms with oxygen. As a result, the carrier concentration was decreased with increasing Si content.

• Korean Journal of Materials Research
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• v.21 no.2
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• pp.89-94
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• 2011

In this work, fabrication and electrochemical analysis of an individual multi-walled carbon nanotube (MWNT) electrode are carried out to confirm the applicability of electrochemical sensing. The reactive ion etching (RIE) process is performed to obtain sensitive MWNT electrodes. In order to characterize the electrochemical properties, an individual MWNT is cut by RIE under oxygen atmosphere into two segments with a small gap: one segment is applied to the working electrode and the other is used as a counter electrode. Electrical contacts are provided by nanolithography to the two MWNT electrodes. Dopamine is specially selected as an analytical molecule for electrochemical detection using the MWNT electrode. Using a quasi-Ag/AgCl reference electrode, which was fabricated by us, the nanoelectrodes are subjected to cyclic voltammetry inside a $2{\mu}L$ droplet of dopamine solution. In the experiment, RIE power is found to be a more effective parameter to cut an individual MWNT and to generate "broken" open state, which shows good electrochemical performance, at the end of the MWNT segments. It is found that the pico-molar level concentration of analytical molecules can be determined by an MWNT electrode. We believe that the MWNT electrode fabricated and treated by RIE has the potential for use in high-sensitivity electrochemical measurement and that the proposed scheme can contribute to device miniaturization.

• Fashion & Textile Research Journal
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• v.13 no.2
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• pp.279-284
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• 2011

In this study, the process of preparation nonwoven with coated carbon nano fibers (CNFs) /poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) composite solution is described. The various contents of CNFs/PVDF-HFP composite coated nonwoven were prepared and characterized by morphological, mechanical, and electrical methods. Nonwovens are coated with CNFs/PVDF-HFP composite solution and decreased the pick up ratio with increasing CNFs contents in range from 0% to 16%. In the results of SEM images, it was clear that the CNFs were evenly distributed in coated nonwoven by SEM images, the existence of CNFs in coated nonwoven was confirmed regularly. The mechanical properties of various contents of CNFs/PVDF-HFP coated nonwoven were examined. The tensile linearity and compression linearity increased with increasing CNFs contents. The electrical properties of the CNFs/PVDF-HFP coated nonwoven increased with increasing CNFs contents.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.387-390
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• 2006

The protective layer of AC-PDP was fabricated by laminating an MgO green sheet. The MgO green sheet was made by coating MgO solution composed of solvent, dispersant, binder, and MgO nano-powder. The MgO solution was coated by the die casting method on the base film. We fabricated three kinds of MgO green sheets of which thicknesses were 20, 28, and $40\;{\mu}m$, respectively. The MgO nano-powder showed lower CL intensity and ${\gamma}i$ than the e-beam MgO. The MgO green sheet applied panels showed low luminance and current density. The efficiency was almost same as the conventional e-beam MgO panel.

• Journal of the Korean institute of surface engineering
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• v.38 no.4
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• pp.167-173
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• 2005

Surface characteristics of HA(hydroxyapatite) coated dental implant alloy by Sol-Gel method were investigated using potentiostat, ICP, SEM, EDX, EPMA and surface roughness tester. Surface roughness of HA coated specimen by Sol-Gel showed higher than that of PVD coated specimen. Corrosion resistance increased in the order of $1\%$ lactic acid, artificial saliva, $0.5\%$ HCI and $0.9\%$ NaCl solution. Amount of Ca element release was higher than that of V and P in the $0.5\%$ HCI and $0.9\%$ NaCl solution.

• Journal of the Korean institute of surface engineering
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• v.44 no.4
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• pp.137-143
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• 2011

The internal stress and magnetic properties (coercivity and squareness) of Ni-Fe nano thin film synthesized by electrodeposition method were studied as a function of acidic chloride bath conditions (composition and temperature) and current density. Fe deposition patterns were different depending on the temperature of the solution, the stress of film decreased with increasing the solution temperature, and the depending on the amount of Fe deposition showed a parabolic shape. The grain size of film was inversely proportional to stress of thin film. The internal stress of thin film and magnetic properties were deeply relevant, and the stress of thin film had a relationship with bath conditions and grain size of the thin film surface.

• Particle and aerosol research
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• v.11 no.3
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• pp.77-85
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• 2015

A Belousov-Zhabotinsky reaction in a liquid-liquid system under microwave radiation was observed under non-stirring conditions. To control this non-equilibrium reaction, nano-particle, which is active under microwave irradiation, was added to the solution. Color changes of the solution during the oscillatory reaction were found to be influenced by the irradiation power although the droplet temperature was equal to the temperature of surrounding oil. During the irradiation, the period of oscillation became shorter because the reaction rate was faster. It could also be observed that there is possibility to eliminate oscillatory behaviors of the reaction using higher power of microwave. The possibility of controlling non-linear reaction using microwave was shown since microwave can easily travel through oil phase and reach water phase.

• Journal of Sensor Science and Technology
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• v.14 no.5
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• pp.297-301
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• 2005

Nanocrystalline SnO and $SnO_{2}$ powder have been prepared by hydrazine method. Sn-Hydrazine complex was formed by the reduction between aqueous $SnCl_{2}$ solution and hydrazine monohydrate. $SnO_{2}$ nano powder was prepared by the decomposition of Sn-Hydrazine complex at $450^{\circ}C$. When NaOH was added to Sn-hydrazine complex, SnO powder with nano-sheet morphology could be prepared. This can be attributed to the role of $OH^{-}$ ion as a reducing agent.

• Korean Journal of Materials Research
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• v.17 no.10
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• pp.544-547
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• 2007

Human teeth were scratched by the abrasive paper, dropping in hydroxyapatite solution during 1, 2, 3, 4 months. We studied teeth surface change with SEM each months. After 1 months treatment the surface appeared the change. Because of the hydroxyapatite ion exchange mechanism. The scratched surface was recovered by the hydroxyapatite. The results of EDS showed that $Ca^{2+}$ ion and $PO_4^{3-}$ ion were removed from hydroxyapatite solution to scratched teeth surface.