• Polymer(Korea)
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• v.39 no.1
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• pp.56-63
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• 2015

The object of this study is to prepare microcapsules containing a diisocyanate compound, apply them to self-healing protective coating, and evaluate the self-healing capability of the coating by atmospheric moisture. Isophorone diisocyanate (IPDI) polymerized under humid atmosphere, indicating that IPDI can be used as a healing agent. Microencapsulations of IPDI were conducted via interfacial polymerization of a polyurethane prepolymer with diol compounds. The formation of microcapsules was confirmed by Fourier-transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy. The mean diameter, size distribution, morphology and shell wall thickness of microcapsules were investigated by optical microscopy and scanning electron microscopy (SEM). The properties of microcapsules were studied by varying agitation rates and diol structure. The self-healing coatings were prepared on test pieces of CRC board. When scratch was generated in the coatings, the core material flew out of the microcapsules and filled the scratch. The self-healing coatings were damaged and healed under atmosphere with 68~89% relative humidity for 48 h, and SEM and impermeability test for the specimens showed that the scratch could be healed by atmospheric moisture.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.135-135
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• 2015

Tubes are of extreme importance in industries as for fluid channels or wave guides. Furthermore, some weapon systems such as cannons use the tubes as gun barrels. To increase the service life of such tubes, a protective coating must be applied to the tubes' inner surface. However, the coating methods applicable to the inner surface of the tubes are very limited due to the geometrical restriction. A small-diameter cylindrical magnetron sputtering gun can be used to deposit coating layers on the inner surface of the large-bore tubes. However, for small-bore tubes with the inner diameter of one inch (~25 mm), the magnetron sputtering method can hardly be accommodated due to the space limitation for permanent magnet assembly. In this study, a new approach to coat the inner surface of small-bore tubes with the inside diameter of one inch was developed. Instead of using permanent magnets for magnetron operation, an external electro-magnet assembly was adopted around the tube to confine the plasma and to sustain the discharge. The electro-magnet was operated in pulse mode to provide the strong axial magnetic field for the magnetron operation, which was synchronized with the negative high-voltage pulse applied to the water-cooled coaxial sputtering target installed inside the tube. By moving the electro-magnet assembly along the tube's axial direction, the inner surface of the tube could be uniformly coated. The inner-surface coating system in this study used the tube itself as the vacuum chamber. The SS-304 tube's inner diameter was 22 mm and the length was ~1 m. A water-cooled Cu tube (sputtering target) of the outer diameter of 12 mm was installed inside of the SS tube (substrate) at the axial position. The 50 mm-long electro-magnet assembly was fed by a current pulse of 250 A at the frequency and pulse width of 100 Hz and 100 usec, respectively. The calculated axial magnetic field strength at the center was ~0.6 Tesla. The central Cu tube was synchronously driven by a HiPIMS power supply at the same frequency of 100 Hz as the electro-magnet and the applied pulse voltage was -1200 V with a pulse width of 500 usec. At 150 mTorr of Ar pressure, the Cu deposition rate of ~10 nm/min could be obtained. In this talk, a new method to sputter coat the inner surface of small-bore tubes would be presented and discussed, which might have broad industrial and military application areas.

• Applied Chemistry for Engineering
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• v.33 no.4
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• pp.444-450
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• 2022

The effect of coated polyester (PET) textiles with metal oxide, chitosan, and copper ion on the antibacterial and antiviral activities was evaluated to investigate the applicability of multi-coated PET textiles as antiviral materials. Compared to coated PETs with a single agent, multi-coated PETs reduced the loading amount of coating materials as well as the contact time with bacteria for a bacterial cell number of < 10 CFU/mL, which was not detectable with the naked eyes. Metal oxides generate reactive oxygen species (ROS) such as free radicals by a catalytic reaction, and copper ions can promote contact killing by the generation of ROS. Chitosan not only enhanced antibacterial activities due to amine groups, but enabled it to be a template to load copper ions. We observed that multi-coated PET textiles have both antibacterial activities for E. coli and S. aureus and antiviral efficiency of more than 99.9% for influenza A (H1N1) and SARS-CoV-2. The multi-coated PET textiles could also be prepared via a roll-to-roll coating process, which showed high antiviral efficacy, demonstrating its potential use in air filtration and antiviral products such as masks and personal protective equipment.

• Journal of Adhesion and Interface
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• v.18 no.3
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• pp.134-140
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• 2017

In this study, we made UV cured acrylic pressure sensitive adhesive containing silicone-urethane-acrylate (SUA) oligomer for a coating on protective film and investigated the effect of SUA oligomer content and UV-dose on adhesion properties. The results illustrated that peel strength decreases with increasing oligomer content and UV-dose, while holding power increases. The gel fractions sharply increased after UV irradiation and then remain constant with prolonged UV exposure. From peel-off test, sample S70 (70% oligomer content) shows the best peelability and removability without remaining any mark or adhesive material on the test substrate than S50 (50% oligomer content) and S60 (60% oligomer content). Sample S70 also showed a surface energy lower than $26mJ/m^2$ and a transmittance higher than 95% at UV-dose 1857 and $2270mJ/cm^2$ which met the required properties for protective film application.

• Journal of the Korea Institute of Building Construction
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• v.14 no.6
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• pp.505-513
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• 2014

The purpose of this study is to evaluate the corrosion protective properties of a Zn-Sn metal spray method according to the contents of Zn and Sn by a CASS test and the electrochemical theory. In the experiment, the CASS test and the electrochemical test were conducted to investigate the corrosion protective property of the Zn-Sn Metal Spray system, the Zinc galvanizing system, and the heavy duty coating system. As a result, it was confirmed that the Zn-Sn (65:35) Metal Spray system had very high corrosion protective property through the electrochemical characteristic as comparison with the other anti-corrosion systems and was very effective to prevent steel products from corrosion.

• Journal of the Korean Society of Safety
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• v.20 no.4 s.72
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• pp.14-19
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• 2005

One area in which composites have been used rather extensively is for fabricating pressure vessel. These structures can be readily manufactured by filament winding, which is, as far as composite fabrication techniques are concerned, a relatively inexpensive method for producing composite structures. Unfortunately, the higher strength material and fabrication costs are not the only disadvantages of fiber-reinforced polymer composites when they are compared to metals. Additionally, these materials tend to exhibit brittle behavior. This is of particular concern when they are subjected to a low-velocity impact during routine handling a significant amount of structural damage can be introduced into the composites. The goals of this paper are to understand the impact damage behavior and identify the effect of surface coating materials on impact resistance in filament wound composite pressure vessels. For these, a series of low velocity impact tests was performed on specimens cutting from the full scale pressure vessel by the instrumented impact testing machine. The specimens are classified into two types with and without surface protective material. The visualization for impact damage is made by metallurgical microscope. Based on the impact force history and damage, the resistance parameters were employed and its validity in identifying the damage resistance of pressure vessel was reviewed. As the results, the impact resistance of the filament wound composites and its dependency on the protective material were evaluated quantitatively.

• Journal of Korean society of Dental Hygiene
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• v.8 no.1
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• pp.59-71
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• 2008

This study was conducted to provide basic data required for the development of dental hygiene project for babies by investigating the relationship between mothers' dental hygiene activities and their socio-economic characteristics and the dental hygiene activities of babies. The survey was carried out with questionnaire to 306 babies of ages from 4 to 7 years and their mothers, from January 5 to January 25, 2007, in 4 kindergartens in Masan, Korea. The collected data was processed with SPSS v.12.0 for frequency analysis and ${\chi}^2$-test per item, to obtain following conclusions. 1. The frequency of toothbrushing of children is two times, accounted for 52.3%, they brush the teeth by them, and accounted for 52.3%, Fluorine toothpaste 68.3%. 2. The frequency of meal of children is 3 times, accounted for 93.5%, they ingestcariogenic snack 1 time, accounted for 45.4%, and they ingest protective and detergent snackfrom dental caries 2 times, accounted for accounted for 45.1%. 3. The shorter the period of mothers' duration of visit to dentists, the more experiences of fluorine coating and help from parent in toothbrushing had the children (pE.01, pE.05). 4. Children of housewife mothers received help from parent in toothbrushing and take teeth care and clean snack more than those of working mothers (pE.05, pE.01). 5. The children of working mothers had fluorine coating more than those of housewife mothers (pE.05). The fluorine coating, toothbrusing, protection and eating green food of babies show significant differences according to the frequency of mothers' visit to dentists and occupation.

• Journal of Powder Materials
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• v.16 no.3
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• pp.185-190
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• 2009

Fe-Cr steels are the most promising candidate for interconnect in solid oxide fuel cells. In this study, an effective, dense and well adherent (LaSr)(CrCo)$O_3$ [LSCC] coating layer was produced onto 430 stainless steel (STS-430) by atmospheric plasma spraying and the oxidation behavior as well as electrical properties of the LSCC coated STS-430 were investigated. A significant oxidation of pristine STS-430 occurred at $800^{\circ}C$ in air environment, leading to the formation of $Cr_2O_3$ and $FeCr_2O_4$ scale layer up to ${\sim}7{\mu}m$ after 1200h, and consequently increased an area specific resistance of $330\;m{\Omega}{\cdot}cm^2$. Although the plasma sprayed LSCC coating contained the characteristic pore network, the coated samples presented apparent advantages in reducing oxidation growth of STS-430, resulting a decrease in oxide scale thickness of ${\sim}1{\mu}m$ at $800^{\circ}C$ after 1200h. The area specific resistance of the LSCC coated STS-430 was much reduced to ${\sim}7\;m{\Omega}{\cdot}cm^2$ after exposure at $800^{\circ}C$ for 1200h, compared to that of the pristine STS-403.

• Journal of the Korean Ceramic Society
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• v.32 no.1
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• pp.95-105
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• 1995

Ceria(CeO2) stabilized zirconia(CeSZ) sol was synthesized with zirconium n-butoxide Zr(OC4H9)4 and cerium nitrate hexahydrate Ce(NO3)3.6H2O as precursors and ethylacetoacetate(EAcAc) as a chelating agent under atmosphere. CeSZ films were deposited on AISI 304 stainless steel using the prepared polymeric sol by dipcoating and the coating characteristics were investigated by XRD, ellipsometry, scratch test and SEM. The CeSZ film began to crystallize from amorphous to tetragonal phase at 40$0^{\circ}C$ and it was not converted into monoclinic phase up to 100$0^{\circ}C$ by the addition of 16mol% CeO2 as a stabilizer which could suppress phase transformation of zirconia. The CeSZ films were prepared by varying the EAcAc contents and the cncentration of CeSZ sol and measured the thickness and refractive index. From these results, it was found that the EAcAc contents and concentration of CeSZ coating sol evidently affect the densification of CeSZ film. The CeSZ film coated with 0.4M CeSZ sol and heat-treated at $600^{\circ}C$ for 10min had thickness of 50nm and 17% porosity. The CeSZ film on 304 stainless steel effectively acted as a protective layer against oxidation up to 80$0^{\circ}C$ and had superior corrosion resistance in 25% H2SO4 solution for 4.5 hrs.

• The Korean Journal of Community Living Science
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• v.17 no.4
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• pp.49-56
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• 2006

The purpose of this study was to evaluate the thermal and subjective comfort of various pesticide-proof clothes made from different material. Seven male adults took part in the study, conducted in a climate-chamber controlled with an ambient temperature of $30^{\circ}C$ and a relative humidity of 60%RH. The thermal and subjective responses of subjects wearing pesticide-proof clothing made of Goretex(coating treatment), polyester (water-repellent treatment), non-woven(coating) and nylon(coating) were measured. The main results were summarized as follows: (1) Change of rectal temperature and clothing microclimate were inhibited more effectively in pesticide-proof clothing made of Goretex, polyester and non-woven than nylon materials. (2) Mean skin temperature at the end of the experiment was significantly higher in subjects who wore nylon than non-woven and Goretex, and was lowest in those with pesticide-proof clothing made of polyester. (3) Change of heart rate was significantly lower in subjects with Goretex and polyester clothiing than those with non-woven, and in those with nylon, it was highest. (4) Subjective comfort was greater in subjects with Goretex, polyester and nonwoven clothing than nylon, except for thermal sensation. Thermal sensation was greater in order of polyester, Goretex, non-woven and nylon. Thus, it was concluded that pesticide-proof clothing made of Goretex, polyester and non-woven material could reduce thermal stress during the spraying of pesticides in summer.