• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.5
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• pp.121-129
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• 2006

This study look into the mechanisms of growth and magnification of the cracks and delamination in the pre-cracked RC beams repaired with carbon fiber sheets. The experimental parameters were loading type, loading speed and crack. In the experiments, it was confirmed that a failure of beams began with development and propagation of the stepped delamination in the below the loading point due to the rapid change of shear force, but mechanisms of the failure were not influenced with loading type, loading speed and pre-cracks. Particularly, in the case of beams having the pre-cracks, growth of crack concentrated at the special crack below the loading point and led to failure of the beam by delamination due to magnification of crack.

• Journal of Korean Tunnelling and Underground Space Association
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• v.17 no.5
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• pp.553-561
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• 2015

In this study, the performance assessment criterion for reasonable maintenance of shield TBM tunnel was presented. The performance assessment items such as crack, leakage, breakage, spalling, exfoliation/detachment, efflorescence, quality condition, exposure of steel, carbonation, faulting step, bolts condition, drainage condition, ground condition, contact section condition and conduit condition were selected by analyzing domestic and foreign performance assessment criterions and investigating segment lining deterioration cases through the site investigation and in-depth inspection analysis result on the shield TBM tunnel. In addition, the reasonable weight using AHP (Analytic Hierarchy Process) were estimated.

• Journal of the Korean Geographical Society
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• v.41 no.6 s.117
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• pp.657-669
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• 2006

Rates and processes of bare patch denudation were observed at Janggumokoreum(1,710m) and Minoruem(1,600m) in order to clarify some characteristics of turf exfoliation in the subalpine grassland of Mt. Halla. The bare patches have marginal terrace fronts with a maximum height of 85 cm. The terrace risers usually develop an overhanging edge 2 to 38 cm long that eventually hangs down and protects the riser beneath. The patches are largely covered with angular pebbles and cobbles. The mean rate of riser retreat for the period 2002-2004 is 39.2 mm, equivalent to 19.6 mm/yr. However, there is a disparity of the rate of riser retreat at individual sites. The maximum rate is 131 mm measured at Janggumokoreum patch while the minimum rate is 0 mm at Minoreum patch. The rate of riser retreat also varies with seasons. The thawing season of April exhibits a maximum rate of retreat. The freezing season of October and November and the rainy season of June and July show relatively high rates of retreat. Several Processes such as frost action, aeolian deflation, rainwash, rainsplash and fauna activity cause the denudation of bare patches. In particular, the needle ire action which is combined with rainwash or deflation plays a primary role in turf exfoliation due to the diurnal freeze-thaw cycles occurred over 100 days, melted snow and strong wind in the subalpine zone of Mt. Halla. Rainwash is also an important contributing process in the rainy season because Mt. Halla has the highest precipitation in Korea. By contrast, rainsplash erosion has a minor effect on the bare patch denudation due to the overhanging edge of terrace risers. Recent increase in roe deer appears to be responsible for turf destruction.