• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.12
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• pp.1188-1193
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• 2007

This study focuses on the corrosion problems of STS316(stainless steel 316) tube for the cooling system of PEMFC (Proton Exchange Membrane Fuel Cell) operation. Deionized water which is highly corrosive is used especially for cooling agent of PEMFC to eliminate electrical conductivity, The tensile stress analysis was performed to check the change of mechanical strength of cooling line and pH of the water was monitored for the observation of extent of corrosion at simulated PEMFC operating condition. When STS316 tube was exposed to deionized water for 500 hours, substantial cracks were found on the surface and the pH of water was decreased from 6.8 to 5.8. For prevention of corrosion problems, the STS316 was coated by three kinds of fluororesin such as PTFE, FEP and ETFE. Among the coating materials, PTFE was the most protective in corrosive environment and was maintained the mechanical strength. To lower the cost, the same experimental analyses were carried out for iron tubes and the result will be discussed in detail.

• Journal of the Korea Furniture Society
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• v.19 no.3
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• pp.172-179
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• 2008

The objective of this study was to investigate the influence of the water repellents' treatment on the water absorptivity and the dimensional stability of Korean red pine wood(Pinus densiflora). The alkylketene dimer(AKD), fluororesin emulsion(Wood-seal, WS), and paraffin wax emulsions(PW25, PW40, and PW1200) were used as water repellents. PW40 and WS were proved as excellent water repellents for pine wood, because the samples treated with these agents showed high contact angles and large reduction in water absorptivities. Also, the dimensional stability(antiswelling efficiency) of pine wood was considerably improved by water repellents treatments, such as PW40 and WS at the pressure of 2MPa. The water repellent treated woods with WS, PW40, and PW1200 at the pressure of 2MPa were relatively stable to the wet-dry cyclic leaching test.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.3A
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• pp.341-347
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• 2008

Among coating systems used for steel bridge coatings on highway such as red lead-pigmented alkyd, chlorinated rubber, waterborne inorganic zinc, inorganic zinc/epoxy/urethane and inorganic zinc/epoxy/fluororesin, evaluation of deterioration degree and prediction of lifetime through regression analysis were carried out for coating systems widely used and grossly degraded. For evaluation of deterioration degree, 75 bridges on highway were selected, and evaluations were carried out according to point offering method regulated by Guideline of maintenance coating for steel bridges used in Korea Expressway Corporation. Lifetime prediction results showed 13.0~13.3 years for the whole nation, 11.8 years for urban and industrial region in the metropolitan area, 13.2 years for rural region except the metropolitan area, 13.5~13.7 years for chlorinated rubber coating systems, and 12.86 years for red lead-pigmented alkyd systems. For prediction of the rest life of coating, we tried to execute parallel translations of standard deterioration curve to current life and deterioration degree for both x and y axes, and it was thought that parallel translation for x axis corresponded to deterioration aspects in actual environment. Maximum and minimum equations were derived from standard deterioration equation by adding and subtracting error values deduced in regression analysis to/from each coefficient in order to establish maintenance coating criteria for overall steel bridges on highway. Whole domain was divided into 8 parts in order to predict the rest life of coating and optimum time of maintenance coating, and maintenance coating criteria for each 8 domains were presented.