• Journal of Korean Society of Environmental Engineers
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• v.38 no.6
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• pp.291-298
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• 2016

Electrochemical water treatment process as a useful treatment method for the removal of non-degradable matter has been consistently studied for several decades. Key process of electrochemical water treatment are oxidation reaction from an anode and reduction from a cathode. In this study, the effect of pre-treatment methods in the insoluble electrode manufacturing process for the water treatment has been evaluated for the life time of electrode The results of this study showed that pre-treatment methods of a base metal such as surface roughness, clean method and interlayer formation influenced to life time of electrode when the same condition (catalyst electrode layer coating method and material system) was applied for pre-treatment methods. This study was conducted by using $IrO_2/Ti$ electrode In the test of sand-blasting process, an electrode manufactured by using sanding media of different sizes resulted in the most effective electrode life time when the size of alumina was used for $212{\sim}180{\mu}m$ praticle size (#80). The most effective method was considered using arc plasma in the additional roughness control and cleaning process, sputtering method to form Ta type interlayer formation process.

• Journal of the Korean Applied Science and Technology
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• v.31 no.4
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• pp.595-601
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• 2014

The microstructures of NATM were examined by SEM, FT-IR spectra, tensile properties, mole % of [NCO/OH], and particle size analyzer. Growing concerns in the environment-friendly industries have led to the development of solvent-free formulations that can be cured. We had synthesized NATM(New Austria Tunnel Method) resin having the ability to protect stainless steel against corrosion. Comparing with general NATM resin and coatings, this resin that synthesized with polyurethane and epoxy was highly stronger in intensity and longer durability. Hybrid resin was composed of polyols, MDI, epoxy, silicone surfactant, catalyst and crosslink agent, and fillers. Moreover, fillers such as fume silica not only accelerated the curing rate but also improved the physical property as thermal barriers. The rigid segments of synthetic resin in mechanical properties were due to fume silica and the increase the mole% of [NCO/OH] for corrosion protection. In conclusion, the hybrid resin microstructure with crosslink agent and fume silica are good material for thermosetting coating of metal substrates such as stainless steel.

• Applied Chemistry for Engineering
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• v.19 no.4
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• pp.388-396
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• 2008

2 Components polyurethane coatings are widely used for the industrial coating in general because of its excellent film performance and the workability which were brought by the 3 dimensional cross linked chain structures being formed after the reaction between polyol and polyisocyanate. 2 components polyurethane can be classified into alkyd polyol, polyester polyol, acrylic polyol and polyester modified acrylic polyol depending on where it is used. This research was conducted under the conditions below; different chemical compositions of resin for paint, set the same conditions of viscosity, thinner and acid value, set alternative polyols, OH values and catalysts, set alternative polyisocyanate hardeners of the paint, measure the reaction rates and dynamic mechanical characteristics using RPT-3000, Rotation Rheometer, DMA and FTIR. The research found that the reactivity between polyol and isocyanate influences the film performance and workability depending on the catalysts, OH values and chemical compositions. We find out that different reaction rate of acrylic polyol and polyester modified acrylic polyol with poly-isocyanate is not influenced on temperature and catalyst. In addition, reaction speed of high hydroxyl content polyol is faster than low hydroxyl equivalent. These results can improve difficult working condition to apply urethane coating.

• Journal of Adhesion and Interface
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• v.15 no.1
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• pp.22-30
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• 2014

Self-photoinitiating acrylate (SPIA) which can undergo self-initiation under UV irradiation was synthesized by a Michael addition in the presence of a base catalyst. The SPIA polymerizations were investigated by photo-differential scanning calorimeter (photo-DSC) and surface physical properties such as pendulum hardness and pencil hardness. The results showed that the SPIA can cure upon UV irradiation by itself without a photoinitiator. But we found out that both the curing rate and the conversion were too low for the self-curing reaction of SPIA. In order to improve the SPIA curing properties, we introduced the SPIA/cationic hybrid system and observed the effects of the addition of commercial free radical type monomer and photoinitiator on the curing behaviors. SPIA/cationic hybrid system was the best suitable to improve the SPIA curing properties. The kinetic analysis indicated that the cationic monomer and photoinitiator apparently accelerated the cure reaction and rate of the hybrid SPIA system, mostly due to the synergistic effect of cationic monomer and photoinitiator increasing the mobility of active species and the generation of reactive species (free radical, cation) during the photopolymerization process. The physical properties showed that, unlike typical free radical system, the hybrid systems did not show oxygen inhibition effect because of cationic reaction on the coating surface.

• Elastomers and Composites
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• v.38 no.3
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• pp.243-250
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• 2003

Polyurethane waterproof (PW) coatings are increasingly demanded in Korea for repairing cracks on old building roofs and construction of many sporting facilities. Calcium carbonate, a common filler, is incorporated in PW compositions. In this study, PW coatings were prepared by substituting a part of calcium carbonate with fly ash. The maximum amounts of calcium carbonate which can be substituted by fly ash obtained in the cyclone and bag filter dust collectors were 20 and 10%, respectively. It was found that the curing rate of PWs ran be controlled by varying the amount of Pb-octoate catalyst. The elongations at break as well as tensile strength and tear strength of PW coatings containing fly ash could also be adjusted such that their values were comparable to those of a standard PW coating by varying relative amounts of some components. However, the amount of cadmium, mercury, and lead leached from PW coatings containing fly ash obtained from the bag filter collector exceeded the respective allowed upper limits, mainly due to the initial high contents of them in the fly ash. On the other hand, PW coatings containing fly ash obtained from the cyclone collector exhibited better mechanical properties and did not release any significant amounts of the heavy metals. Thus, it was concluded that PW coatings containing fly ash can be utilized for practical applications as long as an appropriate fly ash is used.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.10-15
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• 2020

Ultraviolet rays, which have wavelengths smaller than 400 nm, are very harmful to the eyes. Recently, high-energy visible light was also revealed to be harmful to retinal cells. Therefore, polymer eyeglass lenses that can block UV and high-energy visible light are needed for eye health. In this study, high-refractive-index polymer eyeglass lens, n=1.67, were manufactured using the injection-mold method with the m-xylene diisocyanate monomer, 2,3-bis((2-mercaptoethyl)thio)-1-propanethiol monomer, benzotriazole UV absorber, release of alkyl phosphoric ester, dye mixture of CI solvent violet 13, and catalyst of dibutyltin dichloride mixture. A multi-layer anti-reflection coating was applied to manufactured polymer eyeglass lenses for both sides using an E-beam evaporation system. The optical properties of the manufactured lenses with the UV and high-energy visible light-blocking function were analyzed by UV-visible spectrophotometry. As a result, the polymer eyeglass lens with a UV absorber of 0.5 wt. % blocked 99% of UV and high-energy visible light shorter than 411 nm. The average transmittance of the polymer eyeglass lens with a UV absorber of 0.5wt.% was 97.9% in the range of 460 ~ 660 nm for photopic eye sensitivity higher than 10%. Therefore, clear image acquisition in photopic vision is possible.

• Korean Journal of Optics and Photonics
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• v.13 no.3
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• pp.197-203
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• 2002

The TiO$_2$ coating solutions were synthesized with different concentrations (T1-0.7N, T2-2.0N) of hydrochloric acid used as catalyst. and TiO$_2$ thin films were prepared by sol-gel dip coating. Their structural and optical properties were examined as a function of calcination temperature. XRD results showed that T1 thin films calcined at 400~80$0^{\circ}C$ had the anatase phase, while those calcined at 100$0^{\circ}C$ had the rutile phase. T2 thin films calcined at 40$0^{\circ}C$ and $600^{\circ}C$ had the anatase phase, with the rutile phase for calcination at 80$0^{\circ}C$. Crystallinity of T2 thin films was superior to that of T1 thin films. The crystallite size of TiO$_2$ thin films increased with increasing calcination temperature, and the crystallite size of anatase phase in T2 thin films was larger than that in T1 thin films, but the crystallite size of rutile phase in T2 thin films was smaller. The surface morphology of the films showed that the films were formed more densely in the rutile phase than in the anatase phase, this phenomenon appeared conspicuously in T2 thin films. The transmittance of the samples with thin films on quartz glass calcined at 100$0^{\circ}C$ was significantly reduced at wavelength range about 300-700 nm due to the increased absorption originating from the change of crystallite phase and composition of the films and the scattering effect originating from increasing crystallite size. The refractive index of TiO$_2$ thin films increased, and hence the film thickness as well as the porosity of TiO$_2$ thin films decreased with increasing calcination temperature. Furthermore, the refractive index of T2 thin films was higher than T1 thin films, and porosity of T2 films was lower.

• Applied Chemistry for Engineering
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• v.20 no.3
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• pp.279-284
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• 2009

The formation of mesoporous pores in the microporous mordenite crystals was performed by controlled silica extraction on alkaline treatment. Inner tunable mesopore size could be controlled by changing the concentration of alkaline solution. The pore structure of mordenite zeolite was studied by instrumental analysis after alkaline-treatment. To obtain the cage type mesopores, Ti-coating on the ourside mordenite crystals before alkaline treatment was investigated to be the most effective. Polymeric chiral salen Co (III) complexes were successfully encapsulated in mesoporous mordenite zeolite by "ship-in-a-bottle" method. The heterogeneous catalyst could be applied in asymmetric ring opening of epichlorohydrine by water. It showed very excellent enantioselectivity with a high yield in the catalysis.

• Journal of IKEEE
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• v.13 no.4
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• pp.37-42
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• 2009

In this study, nanopower ZnO and $SnO_2$ as sensing materials were prepared by hydrazine and hydrothermal routes, respectively, and were doped with Pd, Ru catalyst. The CO and $NO_2$ sensors were fabricated by coating of sensing materials on the MEMS-based structure with electrodes and heaters. The 0.1 wt% Pd doped $SnO_2$ sensor and Ru doped ZnO sensor showed the high sensor response to CO 30 ppm and $NO_2$ 1 ppm, respectively. The sensor signal was stable. This can be used for the detection of pollutant gases emitted from gasoline engine.

• Korean Journal of Materials Research
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• v.19 no.11
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• pp.607-612
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• 2009

We investigated the effects of Co doping on the NO gas sensing characteristics of ZnO-carbon nanotube (ZnO-CNT) layered composites fabricated by coaxial coating of single-walled CNTs with ZnO using pulsed laser deposition. Structural examinations clearly confirmed a distinct nanostructure of the CNTs coated with ZnO nanoparticles of an average diameter as small as 10 nm and showed little influence of doping 1 at.% Co into ZnO on the morphology of the ZnO-CNT composites. It was found from the gas sensing measurements that 1 at.% Co doping into ZnO gave rise to a significant improvement in the response of the ZnO-CNT composite sensor to NO gas exposure. In particular, the Co-doped ZnO-CNT composite sensor shows a highly sensitive and fast response to NO gas at relatively low temperatures and even at low NO concentrations. The observed significant improvement of the NO gas sensing properties is attributed to an increase in the specific surface area and the role as a catalyst of the doped Co elements. These results suggest that Co-doped ZnOCNT composites are suitable for use as practical high-performance NO gas sensors.