• Journal of Hydrogen and New Energy
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• v.20 no.2
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• pp.95-103
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• 2009

In order to improve the electrochemical, mechanical and electrocatalytic characteristics, engineering plastic of polyether ether ketone (PEEK) as polymer matrix was sulfonated (SPEEK) and the organic-inorganic blend composite membranes has been prepared by loading heteropoly acids (HPAs), including tungstophosphoric acid (TPA), molybdophosphoric acid (MoPA), and tungstosilicic acid (TSiA). And then these were covalently cross-linked (CL-SPEEK/HPA) as the electrolyte and MEA of polymer electrolyte membrane electrolysis (PEME). As a result, the optimum reaction conditions of CL-SPEEK/HPA was established and the electrochemical characteristics such as ion conductivity ($\sigma$) were in the order of magnitude: CL-SPEEK /TPA30 (${\sigma}=0.128\;S/cm^{-1}$) < /MoPA40 (${\sigma}=0.14\;S/cm^{-1})$ < /TSiA30 (${\sigma}=0.22\;S/cm^{-1}$) at $80^{\circ}C$, and mechanical characteristics such as tensile strength: CL-SPEEK /TSiA30 $\fallingdotseq$ /MoPA40 < /TPA30. Consequently, in regards of above characterisitics and oxidation durability, the CL-SPEEK/TPA30 exhibited a better performance in PEME than the others, but CL-SPEEK/MoPA40 showed the best electrocatalytic activity of cell voltage 1.71 V among the composite membranes. The dual effect of higher proton conductivity and electrocatalytic activity with the addition of HPAs, causes a synergy effect.

• Clean Technology
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• v.13 no.1 s.36
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• pp.22-27
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• 2007

Pacquer traditionally has been used to varnish. Many reports have revealed that lacquer has durability and antimicrobial activities. Therefore, we expect that lacquer will be used as a good antifouling agent to solve the environmental problem. Here we chemically synthesized urushiol, a major component in lacquer and two urushiol derivatives, urusiol regioisomer and cardanol. We also analyzed the antimicrobial activities of these molecules to examine the inhibitory effect on the formation of the biofilms. Our results showed that synthesized urushiol and its derivatives have strong antifungal activities. Urushiol also exhibited inhibitory effect on the growth of gram positive bacteria specifically. However urushiol derivatives have low antibacterial activities.

• Elastomers and Composites
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• v.49 no.4
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• pp.341-345
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• 2014

In this study, self-actuated photocatalyst that titanium dioxide doped by more than two transition metal was coated PU foam. The antibacterial and antifungal activity of self-actuated photocatalyst coated PU foam was characterized without light. The antibacterial property of self-actuated photocatalyst coated PU foam was shown to be reduced more than 96%, and the antifungal property was shown to be reduced more than 99.9%. The durability of self-actuated photocatalyst coated PU foam tested by Weather-O-meter showed the 7% reduction of formaldehyde decomposition from 96.5% before test to 89.8% after test. The observation of surface of PU foam coated with self-actuated photocatalyst showed that the catalyst was firmly attached to the surface of polyester fiber without separation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.103-107
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• 2003

The inductively coupled plasma(ICP) etching process was selected to fabricate RF Surface Acoustic Wave(SAW) filters and a Pt thin film was sputtered on a $LiTaO_3$ substrate applied to electrode materials to reduce the spurious response and improve the power durability. Steep sidewall pattern was achieved employing $C_4F_8/Ar/Cl_2$ gas chemistry. We investigated an etching mechanism and parameter dependence of the Pt thin film about $C_4F_8$ addition. Sidewall etch angle was about $80^{\circ}$ at the $C_4F_8$ 20% mixing ratio. Fabricated SAW filter is consists of some series and parallel arm SAW resonators which work as impedance elements and show capacitance characteristics at out of the passband. It can be modified for $800{\sim}900\;MHz$ RF filters. External matching circuits were unnecessary.

• Journal of Adhesion and Interface
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• v.21 no.4
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• pp.162-167
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• 2020

The skin-inspired multimodal soft sensors have been developed through multidisciplinary approaches to mimic the sensing ability with high sensitivity and mechanical durability of human skin. For practical application, although the stimulus discriminability against a complex stimulus composed of various mechanical and thermal stimuli experienced in daily life is essential, it still shows a low level actually. In this paper, we first introduce the operating mechanisms and representative studies of the unimodal soft sensor, and then discuss the recent research trend in the multimodal soft sensors and the stimulus discriminability.

• Applied Chemistry for Engineering
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• v.26 no.2
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• pp.199-204
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• 2015

Thermoplastic road markings are one of the most widely used road markings in the world. However, the durability of domestic road markings is relatively shorter than that of the global average of, approximately, three years. To overcome it, the conventional thermoplastic road markings were prepared by adding polyolefin and oxidized PE wax to conventional petroleum resin. In addition, the melting viscosity was designed below 500 cP at $220^{\circ}C$ as well as the optimum viscosity for spray painting, and embedding ratio of glass beads were controlled about 50~60% by spraying in an interval of 1 second. Also the glass bead adhesive ratio was improved by reducing the amount of $CaCO_3$ below 40 wt%. The retroreflectivity was tested under four different conditions to evaluate the abrasion resistance of thermoplastic road markings. The retroreflectivity coefficient satisfied the international standard ($150mcd{\cdot}m^{-2}{\cdot}lux^{-1}$) in this study, and TPRM-7 was determined as an optimal ratio.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.8
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• pp.3532-3540
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• 2011

In order to improve flux of PTMSP/PDMS dense membrane, PTMSP/PDMS-PEI composite membrane with PEI support was prepared by phase inversion process and dip coating. These membranes were evaluated in terms of the removal of volatile organic compounds such as PCE, TCE, chloroform, 1,1,1-trichloroethane from wastewater by pervaporation. The selectivity and flux of PTMSP/PDMS dense membranes was in the range of 216.2 to 2394.4 and 244.3 to 428.2g/m2h, respectively. And pervaporation property of PTMSP/PDMS-PEI composite membrane was in the range of 215.5 to 2404.2 and 390.4 to 728.6g/m2h, respectively. PTMSP/PDMS-PEI composite membrane has remarkably greater flux than dense membranes with similar selectivity. It was possible for polymeric membranes used in this study to remove PCE selectively which is dissolved small quantity in water among other separable solutes. PTMSP/PDMS-PEI composite membrane showed the best performances among the silicone polymeric membranes, and has better durability and mechanical strength than dense membranes. PTMSP/PDMS-PEI composite membrane should be a useful candidate for the removal of volatile organic compounds dissolved in wastewater.

• Applied Chemistry for Engineering
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• v.8 no.3
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• pp.438-445
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• 1997

${\beta}-PbO_2$ electrode, which was electrodeposited on Ti madras, was prepared and for the decomposition of cyanide in electroplating wastewater. After the investigation of temperature and pH conditions for no hydrogen cyanide evolution during the decomposition of cyanide, the optimum current densities of ${\beta}-PbO_2$ electrodeposition and cyanide decomposition were determined in 500ppm NaCN solution, and durability of ${\beta}-PbO_2$ electrode was also investigated. Hydrogen cyanide was actively generated above $40^{\circ}C$ and was not evolved above pH 13. ${\beta}-PbO_2$ electrode electodeposited at $5A/dm^2$ showed the best cyanide decomposition efficiency The decompostion efficiency was about 70% at low decomposition current density ($0.08A/dm^2$), and it decreased gradually to about 10% as the decomposition current density increased up to $4A/dm^2$. The film of ${\beta}-PbO_2$ electrodeposited was corrosive at $20A/dm^2$ and was broken at $50A/dm^2$.

• Journal of the Korean Chemical Society
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• v.54 no.6
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• pp.749-754
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• 2010

In this study, rubber vulcanization property, change in physical property, morphology and chemical characteristics of blended rubber depending on various IR/CR ratio were investigated for the purpose of the improvement of material property and durability. The effect of surface treatment by chlorine on the friction coefficient was also studied with various conditions of surface treatment. In terms of vulcanization property, as the amount of CR content increased, the speed of cure was decreased, while the density of crosslinking stayed constant. It means hardness and modulus were increased as the CR content increased. It is related to change in cure property and mechanical strength was improved by the effect of crystallization reaction. In the aging property, as the CR content increases, the changed amount of basic properties were decreased, which acts as a reducing factor in change of aged property by complementing weak point in mechanical property. It was found that the degree of property change for surface treated samples were reduced. According to the microscopic result, the degree of surface dispersion on rubber blends was increased by increasing CR content. Rubber surface showed uniform direction in pattern with increased smoothness and luster by treatment with chlorine. The degree of rubber reforming was measured by the remaining amount of chlorine and the friction coefficient was dependent on the amount of chlorine combined with rubber. In the initial stage of surface treatment, from 10 to 40 phr, the friction coefficient of specimen was rapidly reduced. However, as the concentration of chlorine solution increased, the change in friction coefficient was decreased.

• Applied Chemistry for Engineering
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• v.29 no.4
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• pp.382-387
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• 2018

In this study, the reaction characteristics of combined steam and carbon dioxide reforming of methane (CSCRM) reaction using Pd-Ni-YSZ catalyst were investigated according to types of catalysts and gas compositions. Catalysts were prepared in the form of powder and porous disk. The injected gases were supplied at different ratios of $CH_4/CO_2/H_2O$. As a result, the conversion of $CH_4$ and $CO_2$ was improved as a result of using the porous disc type catalyst as compared with that of the powder type catalyst. When the $CH_4/CO_2/H_2O$ ratio of the feed gas was 1 : 0.5 : 0.5, the $H_2/CO$ ratio was adjusted close to 2. However, after 6 hours of the reaction, $CH_4$ conversion was partially reduced by the carbon deposition and the pressure drop increased from 0.1 to 0.8. This issue was then solved by optimizing the water content. As a result, it was confirmed that the durability was secured by preventing the carbon deposition when the gas was supplied at a $CH_4/CO_2/H_2O$ ratio of 1 : 0.5 : 1, and the conversion rate was maintained at a relatively high level.