• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.10a
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• pp.312-317
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• 2002

A experimental try was conducted for the purpose of establishment of the cast iron modification by the metal spray method. The friction and wear resistance properties of the metal sprayed cast iron surface were evaluated. The application experiment for the cast iron modification by the metal spray method was conducted in order to develope the restoring method of the scrapped cast iron cylinder liner of the marine engine.

• Tribology and Lubricants
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• v.22 no.2
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• pp.73-78
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• 2006

The surface modification of automobile parts is of great technological importance for the improvement of corrosion resistance, wear resistance, fatigue strength and so on. Recently, research on the development of the technology of surface modification substituting 6-balance chrome process has progressively been achieved in automobile parts. Although the innovation technology for the improvement of the corrosion-resisting and wear resistant properties through post oxidation after nitrocarburising process had attracted a great attention. For this, anodically potentiodynamic polarisation testing was carried out to corrosion resistance and friction and wear experiment according to applied load and sliding distance was carried out to evaluate the wear resistance of machine structural steel with nitrocarburising and non-nitrocarburising SM45C. The presumed wear volume was calculated with the image processing far evaluation of wear resistance of two materials. The results show that the nitrocarburising had a distinguished corrosion resistance and wear resistance than non-nitrocarburising.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.826-829
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• 2004

Structural Dynamics Modification is very effective technique to improve structure's dynamic characteristics by adding or removing auxiliary structures, changing material property, changing shape of structure. In this research, using the surface grooving technique, shape of base structure was changed to improve its first natural frequency. Utilizing the result of frequency variation analysis, groove shape was formed gathering the many small embossing elements. For this process, Criterion Factor was introduced. To reduce its amount of calculation, the range of target area was restricted to their neighboring area and initial grooving point was selected using high-strain energy. This surface grooving technique was successfully applied to the HDD cover model.

• Journal of the Korean Applied Science and Technology
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• v.15 no.3
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• pp.47-53
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• 1998

The polyimide film surface was modified with KOH aqueous solutions or sulfuric acid. The film thickness was increased by about 10% through the modification of film surface. Hydrolysis of amide bonds and hydration of water induced the increase. The polarity of the film surface increased and identified by contact angle measurement. The depth and roughness of modified was increased. After treatment of surface with water, alkyl and 4-pentyloxyaniline were introduced on the film surface by complex formation between anionic species formed on the imide surface and ammonium ion. The newly introduced alkyl group was identified by FT-IR spectroscopy. Surface polarity reduced dramatically and the roughness was increased after introduction of ammonium salt.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.10a
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• pp.15-19
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• 2002

In this work, the surface modification of carbon/epoxy composites was investigated using UV (ultraviolet ray) surface treatment to increase adhesion strength between the carbon/epoxy composites and adhesives. After UV surface treatment, XPS (X-ray photoelectron spectroscopy) tests were performed to analyze the surface characteristics of the carbon/epoxy composites. Comparing adhesion strengths with the surface characteristics, the effects of the surface modification of carbon/epoxy composites by UV surface treatments on the adhesion strengths were investigated.

• Current Photovoltaic Research
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• v.2 no.3
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• pp.84-87
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• 2014

Protection of solar cell surface is important to prevent from dust, pollen, sand, etc. Therefore, development of large area antifouling film is urgent for high performance of solar cells. The surface of silica spheres was modified to fabricate large area antifouling film. The surface of monodisperse silica spheres has been modified with 3-(trimethoxysilyl) propylmethacrylate (TMSPM) to fabricate large area photonic crystal. Although the surface modification of silica spheres with TMSPM has been failed for the base catalyst, the second trial using acid catalyst showed the following results. The FTIR absorption peak at $1721cm^{-1}$ representing C=O stretching vibration indicates that the TMSPM was attached on the surface of silica spheres. The methanol solution comprised of the surface modified silica spheres (average diameter of 380 nm) and a photoinitiator was poured in the patterned silicon wafer with the dimension of 10 cm x 10 cm and irradiated UV-light during the self-assembly process. The result showed large area crack and defect free nanostructures.

• Bulletin of the Korean Chemical Society
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• v.24 no.10
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• pp.1437-1443
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• 2003

Thermal decomposition of hydrated surface layer of $Mg(OH)_2$ at $500^{\circ}C$ in vacuum turned non-porous MgO into porous one with high surface area of around $270 m^2$/g. Most of its surface area, 74 %, was from micropores, and rest of it was from mesopores in wedge-shaped slits, exhibiting bimodal size distribution centered around 30 and 90${\AA}$. Rehydration followed by subsequent dehydration at $300 ^{\circ}C$ in dynamic vacuum further raised the surface area to 340 $m^2$/g. Fraction of microporous surface area was increased to 93%, and the shape of the mesopores was modified into parallel slits with a specific dimension of 32 ${\AA}$. Application of $Fe_2O_3$ over MgO via iron complex formation did not alter the pore characteristics of MgO core, except slightly increased pore dimension. Over the course of the modification, $Fe_2O_3$ stayed on the surface possibly via spill-over reaction.

• Biotechnology and Bioprocess Engineering:BBE
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• v.10 no.3
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• pp.218-224
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• 2005

Surface modification of glutaraldehyde fixed bovine pericardium (GFBP) was success­fully carried out with hyaluronic acid (HA) derivatives. At first, HA was chemically modified with adipic dihydrazide (ADH) to introduce hydrazide functional group into the carboxyl group of HA backbone. Then, GFBP was surface modified by grafting HA-ADH to the free aldehyde groups on the tissue and the subsequent HA-ADH hydrogel coating. HA-ADH hydrogels could be prepared through selective crosslinking at low pH between hydrazide groups of HA-ADH and crosslinkers containing succinimmidyl moieties with minimized protein denaturation. When HA­ADH hydrogels were prepared at low pH of 4.8 in the presence of erythropoietin (EPO) as a model protein, EPO release was continued up to $85\%$ of total amount of loaded EPO for 4 days. To the contrary, only $30\%$ of EPO was released from HA-ADH hydrogels prepared at pH=7.4, which might be due to the denaturation of EPO during the crosslinking reaction. Because the carboxyl groups on the glucuronic acid residues are recognition sites for HA degradation by hyaluronidase, the HA-ADH hydrogels degraded more slowly than HA hydrogels prepared by the crosslinking reaction of divinyl sulfone with hydroxyl groups of HA. Following a two-week subcutaneous implantation in osteopontin-null mice, clinically significant levels of calcification were observed for the positive controls without any surface modification. However, the calcification of surface modified GFBP with HA-ADH and HA-ADH hydrogels was drastically reduced by more than $85\%$ of the positive controls. The anti-calcification effect of HA surface modification was also confirmed by microscopic analysis of explanted tissue after staining with Alizarin Red S for calcium, which followed the trend as observed with calcium quantification.

• Korean Chemical Engineering Research
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• v.55 no.6
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• pp.791-797
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• 2017

In this study, we optimized a method of PEO-PPO-PEO block copolymer embedding, for solving non-specific protein and biomolecular adsorption and high hydrophobicic surface property, which is widely known as problems of poly (dimethylsiloxane) (PDMS) that has frequently been used in basic biological and its applied research. We assessed its surface modification by controlling the concentration of embedded block copolymer, water-soaking time, and recovery time as variables by contact angle measurements. In order to evaluate its antifouling ability, adsorption of FITC-BSA molecules was quantified. Furthermore, we generated oil-in-water (O/W) emulsion as a proof-of-concept experiment to confirm that the optimized surface modification works properly.

• Geomechanics and Engineering
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• v.2 no.3
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• pp.191-202
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• 2010

The porosity (including the specific surface area and pore volume-diameter distribution) of montmorillonitic soft rock (MSR) was studied experimentally with an electrochemical treatment, based on which the change in porosity was further analyzed from the perspective of its electrokinetic potential (${\zeta}$ potential) and the isoelectric point of the electric double layer on the surface of the soft rock particles. The variation between the ${\zeta}$ potential and porosity was summarized, and used to demonstrate that the properties of softening, degradation in water, swelling, and disintegration of MSR can be modified by electrochemical treatment. The following conclusions were drawn. The specific surface area and total pore volume decreased, whereas the average pore diameter increased after electrochemical modification. The reduction in the specific surface area indicates a reduction in the dispersibility and swelling-shrinking of the clay minerals. After modification, the ${\zeta}$ potential of the soft rock was positive in the anodic zone, there was no isoelectric point, and the rock had lost its properties of softening, degradation in water, swelling, and disintegration. The ${\zeta}$ potential increased in the intermediate and cathodic zones, the isoelectric point was reduced or unchanged, and the rock properties are reduced. When the ${\zeta}$ potential is increased, the specific surface area and the total pore volume were reduced according to the negative exponent law, and the average pore diameter increased according to the exponent law.