• The Journal of Engineering Geology
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• v.14 no.4 s.41
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• pp.461-468
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• 2004

In order to characterize hydraulic property dependant on join roughness in rock mass, this study computed permeability coefficients on each range of joint roughness coefficient (JRC) suggested by Barton(1976). For a quantitative analysis of roughness components spectral analysis using the fast fourier transform was performed to select effective frequencies on each PC range. The results of spectral analyses show that low ranges of the JRC are mainly composed of low frequency domain, while high ranges of the JRC have dominant components at high frequency domain. The inverse Fourier transform made it possible to generate joint models of each JRC range using the effective frequencies of roughness spectrum. The homogenization analysis was applied to calculate permeability coefficient at homogeneous microscale, and then, computes a homogenized permeability coefficient (C-permeability coefficient) at macro scale. Therefore, it is possible to analyze accurate characteristics of permeability reflected with local effect of facture geometry. According to the calculation results, permeability coefficients were distributed between $10^{-3}m/sec\;and\;10^{-4}/sec$. In cases of sheared joint models permeability coefficients were plotted between $10^{-4}m/sec\;and\;10^{-5}/sec$, showing irregular distribution of permeability coefficients on each IRC range. The differences of permeability coefficients for the same aperture models or for the sheared joint models indicate that changes of roughness pattern influence on permeability coefficients. Therefore, the effect of joint roughness should be considered to characterize hydraulic properties in rock joints.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.6
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• pp.1367-1375
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• 2015

The purpose of this paper is to suggest 10 mm aggregate specification for thin layer asphalt pavement using steel slag. Aggregate gradations of conventional dense-graded asphalt mixtures were made by fuller's model, whereas 10 mm dense-graded asphalt mixture was obtained tender mix due to close to the maximum density line. The proposed aggregate gradation specification was made to have enough VMA and well-interlocking refer to foreign standards. The correlation between the proposed aggregate gradation and the properties of mixtures were analyzed using Gradation Ratio (GR) and Compacted Aggregate Density (CAD). The CAD index has a high $R^2$ of 0.86-0.99 because the CAD index is able to reflect various aggregate properties. As the results of evaluation by CAD index the proposed aggregate gradation provides more reliable stability and VMA. The percent passing (%) of aggregate size smaller than 0.3 mm was limited 10% or more for improving crack resistance. This limitation increased for 15% of the asphalt mixture's toughness.

• Journal of Conservation Science
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• v.29 no.3
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• pp.249-259
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• 2013

This study was experimented on accelerated weathering test using salt and freeze-thaw to prove effects of consolidants and consolidation for stone cultural heritage. The samples used four kinds of stones (Gyeongju Namsan Granite, Iksan Granite, Yeongyang Sandstone and Jeongseon Marble) which to distributed by three type of weathering grade (Fresh, Weathered Stone and Highly Weathered Stone) added for thermal treatment. The samples were treated with three consolidants (Wacker OH 100, Remmers KSE 300 and 1T1G), and tested by 500 cycles with freezing-thawing and 50 cycles of salt weathering test. As a results of freezing-thawing test, the crack and destruction occurred from some samples. And total immersed samples maintained effect of consolidation to 200 cycles. Also, The rock particle was fall off and gradually destructed by salts weathering test. The consolidated sample relatively had fewer changes by the weathering than not treated sample. The sprayed sample had not continuous effect on weathering.

• Korean journal of communication and information
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• v.72
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• pp.7-51
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• 2015

Job seeking for young adults after college in South Korea is much fierce and highly competitive. Many job seekers tend to experience despair, frustration, and insecurity in such a dire social situation. This study focuses on the job seeking experiences of younger generation people by closely examining the self-introduction letters. This work pays keen attention to the narrative strategies and portrayal of the applicants' self-described activities in these forms of letters through a detailed textual and cultural analysis. In doing so, this analysis attempts to contextualize the complex structures of feeling for the part of young job seekers as well as various social factors and pressures that influence on them.

• International Journal of Highway Engineering
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• v.9 no.3
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• pp.111-121
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• 2007

During the whole month of December in 2005, Korea experienced both heavy snowfall and freezing temperature in southeast regions, which had caused frost related damages to many pavements laid on top of box culverts. In-situ observation revealed that the formation of ice lenses in subgrade and subsequent unbound layers led to upward heaving and transverse cracks in concrete and asphalt pavements. This has affected the long-term performance of pavements, as well as has threatened drivers' safety for a while. Recently, Korea Expressway Corporation has proposed a design guide to better protect newly constructed unbound pavement layers over culverts from frost heave. A trench drainage system has been selected to effectively draw off water and to alleviate pore-water pressure in soils during the coldest season. This paper presents experimental and analytical backgrounds behind this new design guide. Soil specimens retrieved from the sites are tested to quantify clay content and to estimate the permeability of subgrade. A 2-D ground seepage analysis has been conducted to better understand the changes in pore water pressures as a function of grain size. Finally, an optimum size of trench drainage is determined based on numerical analysis and workability in the field.

• Journal of the Korean Geotechnical Society
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• v.28 no.7
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• pp.41-53
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• 2012

During rainfall period, to identify the characteristics of the infiltration of moisture, electrical resistivity monitering survey was carried out to weathered zone. Four regions of geophysical exploration areas with different rock types, four regions were selected. An area consists of mafic granite and three areas are composed of sedimentary rocks (Sandstone, Shale, Unconsolidated Mudstone). Survey was conducted from June (rainy season) to November (dry season), and during the period the change in resistivity was observed. According to the result of monitoring exploration on Geumjeong and Jinju areas, for the estimation of the standard rainfall, it is necessary to estimate the effects of the antecedent rainfall during the rainy season based on the overall rainfall from June till October and also necessary to consider this for the estimation of the half period. Also, the vertical distribution of the low resistivity anomaly zone does not show that the infiltration of moisture does not occur uniformly from the surface of the ground to the lower ground but shows that it occurs along the relaxed gap of the crack or soil stratum of the weathering zone. In Pohang area, the type of moisture infiltration is different from that of the granite or sedimentary rock. Since, after the rainfall, the rate of infiltration to the lower ground is high and the period of cultivation to the lower bedrock aquifer is short, it has similar effect to that of the antecedent rainfall applied for the estimation of the standard rainfall being presently used. In Danyang, due to the degree of water content of the ground, the duration period of the low resistivity anomaly zone observed in the lower ground of the place where clastic sedimentary rock is distributed is similar to that in Pohang area. The degree of lateral water diffusion at the time of localized heavy rain is the same as that of the sedimentary rock in Jinju. According to the above analysis results, in Danyang area, the period when the antecedent rainfall has its influence is estimated as three weeks or so.