• Geomechanics and Engineering
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• v.8 no.5
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• pp.687-706
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• 2015

Methods commonly used to evaluate the improvement of lime-treated expansive soil include swelling characteristics and unconfined compressive strength. In the field, lime-treated expansive soils are in compacted unsaturated state. Soil water characteristic curves (SWCCs) represent a key parameter to interpret and describe the behavior of unsaturated expansive soil. This paper investigates the use of SWCC as a technique to evaluate improvements acquired by expansive soil after lime treatment. Three different lime contents were considered 2%, 4% and 6% by dry weight of clay. Series of tests were performed to determine the SWCC for the different lime content under curing periods of 7 and 28 day. Correlations between key features of the soil water characteristic curves of lime treated expansive soils and basic engineering behavior such as swelling characteristics and unconfined compression strength were established. Test results revealed that initial slope ($S_1$), saturated water content ($w_{sat}$), and air entry value (AEV) play an important role in reflecting improvement in engineering behavior achieved by lime treatment.

• Journal of The Korean Society of Agricultural Engineers
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• v.46 no.6
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• pp.61-69
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• 2004

The aim of the work described in this paper was to confirm the application of the equation of the soil-water characteristic curves on an unsaturated soil. A series of suction test for unsaturated soils was conducted on the selected 4 kinds of soil using modified pressure extractor apparatus. And it was carried out to analyse The experimental parameters which can be describe the soil-water characteristics, were determined by using the data obtained from the experiment. From the results, it was found that The matric suction varied according to the grain size distribution, amount of fine grain particles and void ratio. Also it was found that the residual degree of saturation was decreased with in crease of the void ratio, but the pore size distribution index and air entry value were increased with in crease of the void ratio. And The application of the soil-water characteristic curve equation was confirmed for the various conditions and the various state by the comparison between the measured degree of saturation and the predicted degree of saturation.

• Structural Engineering and Mechanics
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• v.86 no.1
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• pp.109-118
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• 2023

Any place where exercise is common, such as a club, sports hall, or school, is considered a place for teaching sports. When doing sports, a very safe environment for sports should be chosen. The athlete should consider the safety of sports facilities and equipment, and if there is a defect, he should refrain from exercising in these places. The safety of sports facilities is very effective in creating people's sports activities, with the benefits of staying away from physical harm, enjoying sports, and having mental peace. Everyone has the right to participate in sports and recreation and to ensure that they enjoy a safe environment. The ability to manage and solve issues that may arise plays the most critical role in creating a safe environment. The quality of construction materials used for the construction of sports facilities is of great importance. In this work, the resistance and water repellency of concrete constituents for the construction of sports buildings have been investigated by nanoscience. Nano-concrete material solves the main problem of concrete surfaces, i.e., the entry of water and humidity into the structure. It also gives it a self-cleaning ability with its water repellency. Nanoparticles are placed between pores and cover the cracks, which causes roughness in the surface structure of concrete. The high roughness of the surface of the coated concrete caused its super-hydrophobicity. In hydrophobic surfaces, the higher the contact angle, the more hydrophobic the surface will be. In order to investigate the hydrophobic properties, silica nanoparticles, silica nanoparticles, and fly ash were prepared on concrete, and their properties were analyzed.

• Biomolecules & Therapeutics
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• v.16 no.2
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• pp.118-125
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• 2008

Gardenia jasminoides (G. jasminoides) is traditionally used to treat insomnia, jaundice, emotional disorders, hepatic disease, and inflammatory disease. Previously, we found that geniposide and the water extract of G. jasminoides increased $Cl^-$ influx in neuroblastoma. Here we examined the sychopharmacological activities of G. jasminoides and its constituents. G. jasminoides extract was orally administered at 100 and 200 mg/kg, and genipin and geniposide were intraperitoneally injected at 2, 10, and 20 mg/kg. G. jasminoides extract (200 mg/kg) significantly decreased total open field activity but increased rearing activity in the center of the open field, suggesting an increase in exploratory activity. Genipin and geniposide did not change open field activity, but geniposide (20 mg/kg) increased rearing activity in the central area. The extract (200 mg/kg) significantly decreased rotarod and wire-balancing activity, but genipin and geniposide did not. No compounds influenced thiopental-induced sleeping or electroshock-induced seizures. The extract (200 mg/kg) significantly increased staying time in the open arms of the elevated plus maze and the entry ratio into the open arms, and geniposide (20 mg/kg) also increased open arm entry. Electroshock stress decreased open arm activity, but the extract and geniposide (20 mg/kg) significantly reversed that effect. This results indicate that G. jasminoides extract and geniposide alleviated anxiety with greater efficacy in stressed animals than normal animals.

• Journal of the Economic Geographical Society of Korea
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• v.12 no.2
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• pp.159-178
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• 2009

The purpose of the current study was to evaluate the importance-performance levels for the selection attributes of spa destination and to analyze the gap between importance levels of the selection attributes. The data were collected from the spa visitors to Yuseong spa complex. The findings of the current study were as belows: 1. as the results of factor analysis of 32 selection attributes, five factors were generated, such as "spa and supporting facilities", "surrounding conditions around spa resort", "friendship and the intention of recommendation", "spa water" and "fees of spa entry". 2. the mean analysis showed the statistically significant difference among the selection attributes for importance-performance levels and the mean levels of five factors were rank-ordered as in "spa and supporting facilities", "friendship and the intention of recommendation", "fees of spa entry", and "surrounding conditions around spa resort", "spa water". 3. as the results of IPA, the selection attributes were distributed as belows: 9 attributes were located in I (Keep up the Good Work), 4 attributes were located in II (Possible Overkill), 7 attributes were located in III (Concentrate Here). and 12 attributes were located in IV (Low Priority).

• Journal of the Korean Geotechnical Society
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• v.24 no.6
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• pp.27-35
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• 2008

At low normal stress levels tensile strength of sand varies with either saturation or suction of soil in an up-and-down manner with a peak tensile strength that can occur at any degree of saturation. A theory that accurately predicts tensile strength of wet sand is presented. A closed form expression for tensile strength unifies tensile strength characteristics in all three water retention regimes: pendular, funicular, and capillary. Three parameters are employed in the theory; namely, the Internal friction angle (at low normal stress) ${\phi}_t$, the inverse value of the air-entry pressure ${\alpha}$, and the pore size spectrum parameter n. It is shown that the magnitude of peak tensile strength is dominantly controlled by the ${\alpha}$ parameter. The saturation at which peak tensile strength occurs only depends on the pore size spectrum parameter n.

• Journal of the Korean Geotechnical Society
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• v.30 no.1
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• pp.37-47
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• 2014

Unsaturated hydraulic conductivity (HC) is integrated theoretically from soil water retention curves (SWRC) by Mualem capillary model, but the prediction of HC is extremely sensitive to small variation of matric suction near saturation. Near saturation, the Mualem HC based on smooth SWRC decreases abruptly and has problems in the reliability of hydraulic behavior and the stability of numerical solutions. To improve van Genuchten-Mualem (VGM) HC, the van Genuchten SWRC model is modified within range of low matric suction (arbitrary air entry pressure). At an arbitrary air entry pressure, the VG SWRC is linearized in log scale until full saturation. The modified VG SWRC does not affect the fit of actual retention behavior and either the parameters of original VG SWRC fit. Using the modified VG SWRC, the VGM HC is modified to integrate for each interval decomposed by arbitrary air entry pressure. An analytical solution on modified VGM HC is proposed each interval, to protect the rapid change in HC near saturation. For silty soils, VGM models of HC function underestimate the unsaturated permeability characteristics and especially show rapid reduction near saturation. The modified VGM model predicts more accurate HC functions for Korean weathered soils. Furthermore, near saturation, the saturated HC is conserved by the modified VGM model. After 2-D infiltration analysis of an actual slope, the hydraulic behaviors are compared for VGM and the modified models. The prediction by the proposed model conserved the convergence of solutions on various rainfall conditions. However, the solution by VGM model did not converge since the conductivity near saturation reduced abruptly for heavy rainfall condition. Using VGM model, the factor of safety is overestimated in both initial and final stage during heavy rainfall. Stability analysis based on infiltration analysis could simulate the actual slope failure by the proposed model on HC.

• Journal of Digital Convergence
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• v.16 no.9
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• pp.399-404
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• 2018

The purpose of this study is to raise the drinking rate of Arisu, the tap water in Seoul, and to propose new solution for continuous water quality management and raising awareness. The research scope was limited to point-of-use water treatment system, and based on the this contents I proceed this study how this will help to increase direct drinking rate of Arisu. Through research, Korea has provided users with the ability to filter contaminated tap water simply as water to be rinsed through water purification. Therefore, it was predicted that it would be difficult to improve tap water as drinking water. With this study, I expect that the strength of point-of-use system and the reliability of tap water quality will be raised and hope various product will be developed to improve the perception as drinking water and I also expect that this can be applied to whole country even further in the scope of Seoul city.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.10a
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• pp.183-186
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• 2003

This paper presents the results of slamming experiment using air pressure cylinder to increase the repeatability of the experiment. When it comes to the slamming experiment, the traditional way of doing it has been the free fall experiment. By adopting air pressure cylinder almost equal peak pressures were obtained with that of free fall experiment. Jet takes place when the wedge enters water. Slamming doesn't take place when Dead rise angle is more then 20 degrees.

• Water for future
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• v.17 no.1
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• pp.45-56
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• 1984

The whole process from the model design to the results of the test, of hydraulic model test of restricted entry surge tank of Hapcheon dam, is reviewed with the respect to the flowchart of the experiment. And the experimental results are compared with the numerical values which are calculated by Runge-Kutta-Gill scheme. The comparision show a reasonable agreement. In final design, it doesn't matter that only numerical values are considered in case of the short design period, or difficulties of budget, and or the comparably simple type surge tank as Hapcheon dam.