• The Journal of Engineering Geology
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• v.20 no.4
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• pp.391-399
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• 2010

We performed a hydraulic analysis based on the wetness index of talus slopes in Jungsun, Gangwon province. We estimated the relation between the degree of development of the temporary water system, and talus topography and distribution. We also assessed the distribution of talus based on a map of the wetness index. We divided areas of tallus into stable and unstable types, and estimated the size, distribution and shape-preferred orientation of clasts. We performed numerical simulations of rockfall events to assess the optimum location of rockfall barriers upon talus slopes.

• International Journal of Highway Engineering
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• v.5 no.3 s.17
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• pp.11-20
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• 2003

Concrete structures such as bridges, pavement, and offshore structures are normally subjected to repeated load. Because highway and airfield pavements are to resist tension in bending, fatigue failure behavior is very important the fatigue life of materials. Therefore, in this paper was carried according to the fatigue test method and experiment variables for pavement concrete. The fatigue tests were applied split tension($150{\times}75$ in size) and flexural($150mm{\times}150mm{\times}550mm$ in size) beam fatigue test method. Major experimental variable in the fatigue tests in order to consideration of fatigue life were conducted loading frequency of 1, 5, 10, 20Hz and loading shape of block, sine, triangle and moisture condition of dry and wet condition and curing age of 28day and 56day. The test results show that the effect of loading frequency increasing the frequency increased fatigue life, decreased significant at frequencies below 200 cycles. The effect of loading wave form on fatigue life show that a block decreased, triangular increased in comparison with sine. The effect of moisture condition decreased in wet condition in comparison with dry condition. The effect of curing age increased in 564ays in comparison with 28day.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.44 no.3
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• pp.283-290
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• 2024

Currently, the quality standards for recycled aggregates in Korea are very high, at almost the same level as natural aggregates, so recycled aggregates cannot be widely used for concrete. In particular, it is necessary to evaluate how the moisture conditions and curing conditions of recycled aggregates with high absorption rates and wearing rates affect the compressive strength of concrete. Therefore, in this study, we wanted to investigate the effects on compressive strength through experiments using the moisture conditions and curing conditions of recycled coarse aggregate as variables, and compare the compressive strength characteristics of natural coarse aggregate concrete. As a result of this experimental study, the effect of compressive strength on concrete using recycled coarse aggregates according to curing conditions was similar to that of natural aggregate concrete, and the compressive strength showed a low strength of about 13 to 17 %. The effect of the moisture conditions of recycled coarse aggregates was that in the case of wet curing, concrete using wet aggregate showed slightly higher compressive strength than concrete using dry aggregate, but in the case of air curing, on the contrary, dry recycled aggregate concrete was relatively higher than wet aggregate concrete.

• International Journal of Highway Engineering
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• v.8 no.2 s.28
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• pp.95-104
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• 2006

Hysteresis is a common feature exhibited in hydraulic properties of an unsaturated soil. This study focuses on hysteresis observed in a compacted weathered granite subgrade soils based on the pressure plate laboratory tests. It was found that the Soil-Water Characteristics Curve of a soil is hysteretic and unique. The results also show that the wetting and drying curves predicted using the Fredlund and Xing model is quite close to the laboratory-measured results. For a specific matric suction, water content or coefficient of permeability on a wetting curve is always lower than those found on a drying curve.

• Journal of the Korean Wood Science and Technology
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• v.48 no.3
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• pp.393-404
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• 2020

This study examined the material properties of MDF manufactured using acetylated pinus radiata fibers against moisture and compared the properties with the fiberboard quality standards of KS F 3200. Since acetylated MDF shows very low moisture content, water absorption and thickness swelling than the quality standards, it is expected to have an excellent dimensional stability. The bending strength in wetting condition of the acetylated MDF reached approximately 70% of the bending strength in dry condition, making it suitable for the quality standards. The internal bond of the acetylated MDF in the wetting condition was higher than the minimum internal bond of the quality standards in the dry condition, showing a good water resistance. Since the water droplet contact angle of the acetylated MDF is larger than that of untreated MDF, it is determined that it contributes in improving the water resistance due to the low wettability.

• Journal of the Korean Geotechnical Society
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• v.33 no.4
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• pp.25-34
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• 2017

The soil-water characteristics is the most important state parameter for understanding changes in suction and water contents of unsaturated soil slopes. In the field, the hysteretic behaviors of drying and wetting soil-water characteristic curve are real and the adoption of path-dependent suction-water content is needed to predict the hydro-mechanical analysis of unsaturated soils. In this study, in-situ monitored hydraulic behavior of various soil slopes are compared with the data from numerical analysis with the laboratory soil water characteristic curve. Then, the verifications are performed based on the field monitored data respectively. Therefore, the use of path-dependent soil-water characteristic curves could be more rational for design and analysis of unsaturated soil slopes under rainfall conditions.

• Horticultural Science & Technology
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• v.16 no.2
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• pp.229-232
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• 1998

This study was conducted to determine the properties of seedling plate papers currently used in commercial production, then to get basic information for manufacturing new seedling plate paper. Imported seedling plate paper had high wet tensile and burst strengths in its usage circumstances. Wet tensile strength was very high with 38.7% of dry tensile strength. Wet burst strength was also very high with 62.4% of dry burst strength. The seedling plate paper contained about 30% of synthetic fibers. It had 10 Gurley sec. in air permeability indicating effective movement of air. Seedling plate papers were' made in laboratory scale. For sufficient sizing degree, the addition of 0.5% AKD (alkylketene dimer) by weight was good enough. Additional amount of AKD more than 0.5% by weight caused strength loss even though improving sizing effect. The addition of wet strength reagent such as Finex-B 2% by weight resulted in good strength and air permeability.

• Journal of the Korean Geosynthetics Society
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• v.21 no.4
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• pp.93-100
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• 2022

This study describes the evaluation results on the effect of soil particle surfaces coated with various hydrophobic conditions on spectral information according to water content. Wettability test and spectral information evaluation test were performed on the hydrophobic coated standard sand. When the standard sand was coated with 1%, 3%, and 5% hydrophobic, the contact angles of sand-water interface were 130°~143°, 129°~144°, and 131°~144°, respectively. This means that the contact angle increased as the degree of hydrophobic coating increased at the same drying time, but the range of the contact angle had the same wettability. This means that the contact angle increases as the hydrophobic coating degree increases at the same drying time, whereas the contact angle range has the same wettability. As a result of spectral information evaluation, the maximum spectral reflectance of the dried sand with hydrophobic condition decreased compared to that of the hydrophilic sand, as the degree of hydrophobic increased. However, the maximum spectral reflectance was increased by increasing the degree of hydrophobic under the same water content conditions.

• Restorative Dentistry and Endodontics
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• v.24 no.4
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• pp.570-577
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• 1999

Intuitively, higher bond strengths should result in less leakage. However, the relationship between bond strengths and microleakage value is complex and not clearly understood. The purpose of this study was to evaluate the relationship between tensile bond strengths and microleakage values in the same restorations to understand the behavior of resin bonding to tooth structure. One-hundred and twenty enamel or dentin specimens from freshly extracted bovine mandibular incisors were used. The specimen was treated with 32% phosphoric acid for 15 seconds and rinsed for 20 seconds. the teeth were divided into four groups by means of wet bonding technique or dry bonding. One-Step$^{TM}$ adhesive were applied to the specimen. The specimens were immersed in 2% methylene blue solution for 7 days, and tensile bond strength and microleakage were measured. The results were as follows: 1. Significant negative correlation was found between bond strengths and micro leakage values. Hence, higher bond strengths seem to be associated with lower microleakage, and vice versa (r=-0 50, p<0.05). 2. The Enamel/Wet group showed significantly higher bond strength than Enamel/Dry one, and Dentin/Wet group showed higher strength than Dentin/Dry one (p<0.05). 3. Microleakage was significantly less ill wet bonding than in dry one at dentin (p<0.05), however, there was no significant difference between wet and dry bonding at enamel (p>0.05).

• Journal of Korea Water Resources Association
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• v.52 no.9
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• pp.615-626
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• 2019

Soil moisture and runoff have very close relationship. Especially the water retention capacity and drainage characteristics of the soil are determined by various factors of the soil. In this study, a total of 40 rainfall events were identified from the entire rainfall events of Sulma basin in 2016 and 2017. For each selected events, the constant-K method was used to separate direct runoff and baseflow from total flow and calculate the runoff coefficient which shows positive exponential curve with Antecedent Soil Moisture (ASM). In addition to that, the threshold of soil moisture was determined at the point where the runoff coefficient starts increasing dramatically. The threshold of soil moisture shows great correlation with runoff and depth to water table. It was founded that not only ASM but also various factors, such as Initial Soil Moisture (ISM), storage capacity of soil and precipitation, affect the results of runoff response. Furthermore, wet condition and dry condition are separated by ASM threshold and the start and peak response are analyzed. And the results show that the response under wet condition occurred more quickly than that of dry condition. In most events occurred in dry condition, factors reached peak in order of soil moisture, depth to water table and runoff. However, in wet condition, they reached peak in order of depth to water table, runoff and soil moisture. These results will help identify the interaction among factors which affect the runoff, and it will help establish the relationship between various soil conditions and runoff.