• Journal of Applied Reliability
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• v.7 no.4
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• pp.173-181
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• 2007

Out door exposure to daylight and weather climate conditions can cause adverse effect on the properties of automotive plastic materials. The effects of sunlight exposure, especially ultra violet (UV) radiation, can break down the chemical bonds in a polymeric material. This degradation process is called photo-degradation and ultimately leads to color changes, cracking, chalking, the loss of physical properties and deterioration of other properties. To explore the effect of sunlight exposure on the automotive materials, this study investigated photo-oxidation degree and surface property change of molding parts by analytical methods. For the further study, accelerated weathering test methods are proposed, which can correlate with out door weathering, to predict long term performance of automotive plastic materials.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.05a
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• pp.151-154
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• 2002

The durability of two kinds of CFRP plates, carbon/UP and carbon/V, was studied under severe environmental conditions. Immersion into the chemical solutions and accelerated weathering were executed on the CFRP plates and the weight change under each condition was measured. After those treatments, the plates were tested by tensile testing machine to measure the mechanical properties and observed by SEM to find the damage behaviour of the surface. Comparing the virgin plates and the chemically exposed plates, both plates show severe deterioration of the mechanical properties. But, the plates subjected to alkali solution show much larger reduction than those of acidic solution and carbon/V has better chemical resistance than carbon/UP. The material properties of CFRP plate exposed to the weathering were deteriorated linearly proportional to the exposure time.

• Applied Chemistry for Engineering
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• v.5 no.4
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• pp.722-730
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• 1994

The effects of antioxidant and carbon black on weatherability of crosslinked polythylene(XLPE) for electrical insulation were investigated. 16 compositions were prepared in other to determine the weathering resistance. Samples were exposed in xenon-arc lamp Weather-Ometer for 500, 1000, 1500, 2000 hours respectively. Tensile strength, elongation at break, dielectric strength and tan ${\delta}$ were measured to evaluate the weatherability of XLPE. The results indicated that the effect of carbon black was more prominent than antioxidant and synergistic effect, was observed when two additives were mixed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.5 no.1
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• pp.131-140
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• 2001

In general, the deterioration induced by the freezing and thawing cyclic in concrete structures often leads to the reduction in concrete durability by the cracking or surface spalling. If it can prediction of concrete deterioration subjected to cyclic freezing and thawing, we can rationally do the design of mix proportion in view of concrete durability and the maintenance management of concrete structures. Therefore in this study a prediction method of deterioration for concrete structures subjected to the irregular freezing and thawing is proposed from the results of accelerated laboratory freezing and thawing test using the constant temperature condition and the in-situ weathering data. Furthermore, to accurately predict the concrete deterioration, a method of modification for the effect of hydration increasing during rapid freezing and thawing test is investigated.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.1D
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• pp.91-98
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• 2011

Recently, the usage of elastic paving using EPDM Chip instead of pedestrian sidewalk blocks or permeable concrete used mostly for pedestrian walk, trails and in parks has been increassed as it can absorb impact during walking and produce wide range of colors and designs. However, the properties of EPDM Chip including elasticity and durability are decreased when exposed to ultraviolet ray and scenic paving functions through various colors are lowered due to the yellowing phenomenon. In this study, ultraviolet ray accelerated weathering test has been conducted to analyze the color changes in EPDM Chip and polyurethane resin, which are the main ingredients of elastic paving, when exposed to ultraviolet ray. The color differences are quantitatively analyzed through the color value coordination of the colored space by using the color difference scheme. The experimental results show that the color changes in BL polyurethane resin which is used most frequently at present was larger than that of EPDM Chip. Moreover, the total color difference, ${\Delta}E$, of BC polyurethane resin are 3.162 on the $14^{th}$ day of commencement of acceleration, which is 6 times greater color change resistance against ultraviolet ray than that of BL polyurethane resin with total color difference of 20.639. Therefore, the usage of BC polyurethane resin, which is manufactured to have chain-type molecular structure by using the isocyanate as the HMDI at the time of producing polymer, as binder in elastic paving with EPDM Chip is found to be a highly efficient method of restraining the color changes due to the ultraviolet ray.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2006.09a
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• pp.264-267
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• 2006

• Journal of the Korea Furniture Society
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• v.13 no.1
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• pp.27-37
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• 2002

This study was investigated with the surface properties such as physical and accelerated tests of wood-based floorings. In physical test, hardness and abrasion resistance values of laminate floorings were higher than those of others. The center line average surface roughness($R_a$) of imported laminate flooring was highest value($1.34{\mu}m$) and that of imported solid wood flooring was lowest value($0.62{\mu}m$). In cold resistance and moist heat resistance, no defects were found on the surface of all flooring (crack, blistering, peeling, and gloss loss etc.) after testing. Wet-cold-dry cycle test showed that plywood flooring appeared some cracks. In accelerated weathering test, color difference increased with increasing Xenon arc light irradiation

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.196-203
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• 2008

Durability of geosynthetics for soil reinforcement is accounted for creep and creep rupture, installation damage and weathering, chemical and biological degradation. Among these, the long-term creep properties have been considered as the most important factors which are directly related to the failure of geosynthetic-reinforced soil(GRS). However, the creep test methods and strain limits are too various to compare the test results with each other. The most widely used test methods are conventional creep test, time-temperature superposition and stepped isothermal method as accelerated creep tests. Recently developed design guidelines recommend that creep-rupture curve be used to determine the creep reduction factor($RF_{CR}$) which is a conservative approach. In this study, the different creep test methods were compared and the creep reduction factors were estimated at different creep strain limits of 10% of total creep strain and creep rupture. In order to minimize the impact of creep strain to the GRS structures, the various creep reduction factors using different creep test methods should be investigated and then the most appropriated one should be selected for incorporating into the design.

• International Journal of Highway Engineering
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• v.7 no.3 s.25
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• pp.93-100
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• 2005

Rock produced in situ has been used as the road construction materials in consideration of economies. However, because sedimentary rock is rapidly weathered, it is hard to decide appropriateness of quality specifications. This study aims at evaluation of usability for sub-base of muddy stone produced in situ. Test results show that the abrasion ratio is fitted for specifications, but weight loss in 37.5$\sim$16mm after Los Angeles abrasion test shows 47% in muddy stone in comparison with 20$\sim$30% in gneiss and sandstone. The soundness of aggregate shows higher value in muddy stone than in gneiss and sandstone. The weight loss from accelerated weathering test due to freezing and drying show 58% in muddy stone in comparison with 308$\sim$21% gneiss and sandstone.

• Journal of Navigation and Port Research
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• v.43 no.2
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• pp.79-85
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• 2019

Climate change is a very vital issue that can be no longer avoided. Korea has been a top-level country Iin dealing with carbon dioxide emissions since 1960. Many studies have been conducted to suppress or eliminate carbon dioxide emissions, which account for a large portion of greenhouse gases. Carbon Capture and Storage (CCS), the most practical method of them, plays a significant role. However, these methods have the disadvantage of the limits of geographical distribution and high possibility of re-emission into the atmosphere. Recently, ocean storage has been studied using Accelerated Weathering of Limestone (AWL), a technique for storing carbon dioxide in the ocean as an alternative to CCS, an underground storage. AWL is a method of converting carbon dioxide into concentrated water in the form of bicarbonate ion and discharging it to the ocean to dilute and store it. It does not cause re-emission to the atmosphere, and the discharged concentrated water increases the alkalinity of the ocean to prevent marine acidification. The objective of this study was to understand the behavior of DIC (Dissolved Inorganic Carbon) including carbon dioxide during the ocean discharge of bicarbonate ion concentrated water in AWL method. This study area was set near Ulleung-do where sufficient water depth and operational efficiency were secured. CORMIX model was used to calculate the material diffusion by submerged discharge using ship.