• Proceedings of the Membrane Society of Korea Conference
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• 1997.04a
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• pp.87-109
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• 1997

Reverse osmosis(R/O), ultrafiltration(UF) and microfiltration (MF) processes are widely used for water treatment. In the seminar, characteristics of typical membrane modules including tubular, hollow fiber, plate and frame and spiral wound types will be discussed in detail. The design methods based on hydrodynamics for hollow fiber and spiral wound modules will be introduced analytically. Concentration polarization (CP) and membrane fouling mechnism as well as the techniques for CP reduction will be handled. The CP control techniques contain chemically modified membrane surface, pretreatment of feed water, operation of low trans-membrane pressure, chemical or physical cleaning methods and artificial production of various fluid turbulences near the membrane surface, etc. In especially, the recent commercial membrane modules for CP control including module rotation, vibration and Taylor or Dean vortex system will be introduced and discussed in detail.

• Korean Membrane Journal
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• v.1 no.1
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• pp.100-105
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• 1999

A novel system to thicken the concentrated colloidal solution from membrane water treat-ment processes was developed. A hollow-fiber microfilter(hydrophilic polyethylene nominal pore size 0.1 ${\mu}$m total surface area 0.42 m2) was installed in an acrylic housing that has an aeration port 5 cm below the membrane and a clarifier in the bottom. The concentrate was uniformly supplied from the top of the housing. Bacuum filtration caused downward flow of concentrate and as a result thickening interface. The addition of poly-aluminum chloride (PAC) resulted in rapid increase of trans-membrane pressure (TMP) and in no improvement of the filtered water turbidity and thickening process. Two types of con-centrate and concentrate turbidity had little effect on the increase of TMP and concentrate thickening. It was observed that for the same height of membrane housing membrane surface area to housing volume (A/V) ratio had significant effect on the increase of TMP. When the housing volume was increased ten times the increasing rate of TMP was three times faster as compared to the original housing. A hydraulic model successfully simulated the formation and sedimentation of thickening interface.

• Journal of the Society of Disaster Information
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• v.12 no.1
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• pp.54-61
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• 2016

The use of advanced composite materials in strengthening and repair of existing structures is increasing rapidly. This paper describes an effectiveness of a bonding of carbon fiber reinforced sheets to corroded steel members for the repair. Three types of surface treatment, what we call cleaning, of corroded plate are chosen as parameters. They are "without cleaning","removal of painting by brushing" and "complete removal of painting". From the experimental study, the following findings are obtained. 1) When the steel plate is subjected to tensile force, carbon fiber sheets adhered to the painted steel gives a higher strength against peeling compared to that of the plate without painting, 2) The grade of surface treatment, or cleaning of the corroded steel plate affects the strengthening effect.

• The Journal of the Korean dental association
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• v.54 no.1
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• pp.21-26
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• 2016

The requirements for the successful treatment of all-ceramic restorations are not so different from the ones of conventional restorations. "The provisional restoration followed by an adequate tooth reduction" and "the accurately fitting prostheses with corresponding to final impression" can be the examples of them. Nevertheless, the one which all-ceramic restorations are distinguished from conventional restorations is the additional procedure of so called "bonding". In addition to the application of resin cement between "inner surface of restoration and outer surface of abutment", bonding technology can be also applied to the treatment process of "Post and Core" in particular if the abutments are non-vital teeth. Core build-up for all-ceramic crown is conducted with fiber post and tooth colored composite by considering the properties of the restorations transmitting light. I would like to share my clinical experience about "silica based ceramic and non silica based ceramic restoration.

• Fibers and Polymers
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• v.3 no.4
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• pp.174-178
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• 2002

A plasma treatment using saturated $CF_4$ gas was employed to improve the resistance of polypropylene fabrics to water wetting. The fabrics were significantly fluorinated even within a short treatment time of 30 seconds. The result of contact angle measurement indicated that such highly hydrophobic surface was considerably durable even after 150 days of aging.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.38 no.2 s.115
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• pp.22-34
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• 2006

To improve the mechanical properties of Hanji, starches such as maize, konyaku, and wheat powders were added at various concentrations in the manufacturing processes of Hanji. The effect of starches on the physical properties of Hanji was as follows. Filling rates of surface of hanji were increased with the increase of the concentration of starch. Hanji surface were completely filled at the 3.0% konyaku treatment. Konyaku powder showed higher filling rates than maize and wheat powder. The breaking length was increased with the increase of filling rates. Konyaku powder showed the highest breaking length: Tear index of hanji treated with maize and wheat powder were a little improved but that of hanji treated with konyaku powder were a little decreased compared to non-treated hanji. In conclusion, starch treatment showed the increase of the breaking length, but no effect on tear index.

• Journal of the Korean Graphic Arts Communication Society
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• v.24 no.1
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• pp.13-22
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• 2006

We investigated the effects of the enzyme treatment of fiber for printability of coated paper. The results could summarized as follows, 1. The samples with enzyme treatment (average 87.8%) have higher ink gloss than the blank (85.6%). Printed density showed same trends with the ink gloss. However, the ${\beta}$-Glucosidase treated sample showed the lowest printed density (2.14 %) due to the lowest thickness of the ink layer, which is influenced by coated weight and surface smoothness. 2. The samples whose base paper was Xylanase and ${\beta}$-Glucosidase treated showed higher surface strength (4.2% and 4.0%, respectively) than the blank while the samples with the Hernicellulase and ${\beta}$-Glucuronidase treatment showed lower surface strength (3.2%and 3.7%, respectively) due to the influence of air permeability. 3. Hemicellulase and ${\beta}$-Glucuronidase treated base paper, which have relatively low air permeability, showed better ink repellence (4.3 and 4.4 %, respectively) than the blank (3.8 %). 4. The blank and the Xylanase treated base paper showed high set-off, which is the last category of printability.

• Journal of Adhesion and Interface
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• v.9 no.4
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• pp.1-11
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• 2008

In the present study, kenaf fibers were treated with sodium hydroxide using soaking and ultrasonic methods prior to biocomposite processing, respectively. The effect of alkali treatment on the kenaf-PLA interfacial adhesion and mechanical and thermal characteristics of kenaf/poly(lactic acid) biocomposites was investigated in terms of their interfacial shear strength, flexural properties, dynamic mechanical properties and thermal stability and also microscopic observations of kenaf fibers and the composite fracture surfaces. As a result, use of both soaking and ultrasonic methods for treating kenaf fiber surfaces played a role in increasing the fiber-matrix adhesion and the mechanical properties of the biocomposites. Their characteristics depended not only on the fiber surface treatment method but also on the treatment condition like alkali concentration and treatment time.

• Korean Journal of Materials Research
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• v.9 no.1
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• pp.30-34
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• 1999

A polyacrylonitrile(PAN)-based carbon fiber tow was heat-treated by directly passing electric current through the tow. The effects of the stretching stress applied during high temperature heat-treatment of PAN-based carbon fibers were investigated by measuring the electric resistance changes taking place during the internal resistance heating. The structure parameters characterizing the stacks of carbon layer, such as interlayer spacing, sizes and orientation of the carbon fibers heat-treated with hot-stretching were evaluated as a function of surface temperature of tow during heat treatment in the range of $1000~2400^{\circ}C$. Though the layer extent in the fiber axis direction depends strongly on the electric resistance, the changes in a crystallite parameter is independent of the longitudinal strain.

• Composites Research
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• v.31 no.6
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• pp.379-384
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• 2018

This paper aims to study flow characteristics of epoxy resin w.r.t. the sizing agents treated on the carbon fibers which have the same surface morphologies before sizing treatment. Dynamic contact angle (DCA) was measured to evaluate wettability of a single carbon fiber. Wicking test and Vacuum Assisted Resin Transfer Molding (VARTM) were performed to find relation between DCA measurement results and impregnation characteristics. In addition, surface properties of the carbon fibers such as surface free energy and chemical compositions were measured and interfacial shear strength (IFSS) between the carbon fiber and the resin were experimentally characterized by using micro-droplet tests. According to these experimental results, the sizing agent for carbon fibers should have appropriate level of surface free energy and good chemical compatibility with the resin to reconcile resin flow characteristics and interfacial strength.