• Journal of the Korean Geotechnical Society
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• v.26 no.4
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• pp.15-26
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• 2010

To determine the frost heave suppressing mechanism of soil mixed with tire powder, we conducted three kinds of laboratory experiments: measurement of unfrozen water, evaluation of thermal conductivity, and a frost heave. In this research, we focused on changes in the coefficient of permeability of the mixed soil, and first found that of the unsaturated soil. Next, in the case of the presence of ice, we took the ice-impeding factor into consideration to derive the coefficient of permeability of the frozen fringe from the area ratio of the soil and tire powder in mixed soil. The results show a positive correlation between the water intake rate and the coefficient of permeability. Moreover, we found that the frost heave decreased thanks to a reduction in the permeability and a fall in the unfrozen water content of the soil mixed with tire powder. We also calculated the weight of the water content of the soil and tire powder void quantitatively using the result of the volumetric ratio of mixed soil.

• Journal of the Korea Organic Resources Recycling Association
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• v.5 no.2
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• pp.57-64
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• 1997

This study was performed to investigate the characteristics of compost produced from the composting facility at Nanjido. The capacity of the facility is 10 ton/day. Feed material was food waste generated in Seoul. Moisture content of the compost product was 31% and conductivity was 2.6 mmhos/cm. The compost product met Korean quality standards and EC quality standards for VS and C/N ratio. In case of TOC and TKN, they were met with Japan quality standards. The water soluble-C/N ratio finally reached about 5 based on dry compost. The color of compost product was dark brown. The product had earthy smell. Heavy metal contents of the compost were below Korean quality standards by wet basis.

• Journal of the Korean Geotechnical Society
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• v.32 no.12
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• pp.59-67
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• 2016

The strength of frozen soils is affected by size and shape of particles, and the amount of ice and unfrozen water. The objective of this study is to characterize the unfrozen water content and the unconfined compressive strength of the frozen soils according to the degree of saturations and silt fractions. The specimens are mixtures of sand, silt, and water. The silt fractions (SF), which are the ratio of the silt weight ($W_{silt}$) to the sand weight ($W_{sand}$), are 10% and 30%. In addition, the degrees of the saturation are 5%, 10%, 15%, and 20%. The specimens are frozen under the temperature of $-10^{\circ}C$ conditions. The uniaxial compression tests are conducted for 24 hours, 48 hours, and 72 hours after freezing to determine proper freezing time. The freezing time of 24 hours is chosen because the unconfined compressive strengths of specimens after 24 hours freezing times are similar to each other. Furthermore, the unfrozen water content is monitored during freezing using the TDR system. The unfrozen water content increases with the increase of the silt fraction and degree of saturation. The unconfined compressive strength of the frozen soils exponentially increases with increasing the degree of saturation. This study shows that the amount of ice has more influence on the strength of the frozen soils than the amount of unfrozen water.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.7 no.6
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• pp.39-48
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• 2004

The purpose of this paper was to confirm the application of the equation of the soil-water characteristic curve on an unsaturated soil. To this ends, a series of suction test was conducted on the selected 4 kinds of soil which is located in Korea, using the modified pressure extractor apparatus. And it was carried out to analyze the experimental parameters which can 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 was varied according to the grain size distribution, amount of fine grain particle and void ratio. Also it was found that the residual volumetric water content was decreased with the void ratio, but the index related air entry value, the soil parameter related water content and the parameter with residual water content were increased with the void ratio. And the application of equation of the soil-water characteristic curve was confirmed for the various conditions and the various state by the comparison between the volumetric water content measured by the experiment and the predicted values.

• 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.

• Journal of Conservation Science
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• v.30 no.3
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• pp.287-298
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• 2014

This study investigates the material properties of the traditional bricks used in the royal tomb of King Muryeong. Compressive strengths, thermal conductivities, absorptance and the rate of residual moisture are measured by non-destructive experiments. Compressive strength of the traditional bricks is estimated by using the ultrasonic wave velocity and the absorptance. Based on the experimental results, the predicted compressive strengths using the ultrasonic wave velocity are unsuitable for the traditional bricks due to the rough surface and thickness variation of the specimens. The strengths using the absorptance are more suitable than those using the velocity because the predicted average strengths (28.69 MPa ~ 33.19 MPa) are close to building materials like normal strength concrete. In addition, the methods using the absorptance are not influenced by surface and thickness conditions of the specimens. The average thermal conductivities of the bricks measured by using Mathis TCi are close to those of soils (1.58 W/mK). The absorptance and the rate of residual moisture of the bricks are 1.6 % ~ 15 %, 0 % ~ 0.7 %, respectively.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.1
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• pp.93-103
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• 2017

Many countries are interested in the development of the Antarctic area because of the abundant resources and living things of high research value. Korea completed the second Antarctic research station in 2014 and spurring the development of the Antarctic area by constructing runway for the airplanes and a third Antarctic research station. However, frozen soils, unlike typical soils, are sensitive to creep behavior due to the influence of ice and unfrozen water. The creep tests for evaluating creep behaviors on the frozen soils require expensive laboratory equipments and large amount of time. Thus, various empirical models had been developed to describe the unconfined compressive creep behavior of frozen soils. In this study, new analytical creep model on frozen sands was proposed by modifying Ting's Tertiary creep model with a new parameter considering fine contents. Thus, the unconfined compressive creep tests were conducted with the frozen specimens of dense Jumoonjin sand with fine contents of 0, 5, 10 and 15% under various loads at -$5^{\circ}C$, -$10^{\circ}C$ and -$15^{\circ}C$. Consequently, the modified Tertiary creep model with a new parameter for fine contents are not enough for the description of the acutal creep behavior of the frozen sand and new framework should be developed.

• Journal of the Korean Geotechnical Society
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• v.38 no.8
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• pp.7-15
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• 2022

Most studies have conducted cryogenic triaxial compression tests with frozen specimens prepared in a separate mold by one-directional freezing. This method has the potential to generate residual stress in a frozen specimen and cannot be adopted to simulate the application of the artificial ground freezing method in the field. Therefore, in this study, novel equipment and procedure for the cryogenic triaxial compression test were proposed to overcome the limitations of existing test methods. Therefore, the mechanical characteristics of frozen sand, considering the effect of temperature and confining pressure, were evaluated. As the freezing temperature decreased, the brittleness of frozen sand increased, and the strength increased due to a decrease in the unfrozen water content and an increase in the ice strength. A higher confining pressure resulted in an increase in interparticle friction and the pressure melting phenomenon, which caused strength reduction. Thus, it was found that the mechanical behaviors of frozen sand were simultaneously affected by both temperature and confining pressure.

• Journal of the Korean Geotechnical Society
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• v.19 no.1
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• pp.41-49
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• 2003

Rainfall-induced landslides in a weathered granite soil slope usually happen on shallow slip surfaces above the groundwater table. The pore-water pressure of soil above the groundwater table is usually negative. This negative pore-water pressure (or matric suction) has been found to make a large contribution to the slope stability. Therefore, the variation of in-situ matric suction profiles with time elapse in a soil slope should be understood. In this study, a field measurement program was carried out from June to August, 2001 in order to monitor in-situ matric suctions and volumetric water contents in a weathered granite soil slope. Finite-element transient seepage analyses are also conducted using SEEP/W. The influence of climatic conditions on the variation of in-situ matric suctions could be found to decrease rapidly with the change of depth. It could be found that decrement of matric suction induced by precipitation is affected not only by the amount and duration of rainfalls but also by the initial matric suction just prior to rainstorms. The soil-water characteristic from the field monitoring tends toward the wetting path of SWCC obtained from the laboratory test.

• Food Science and Preservation
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• v.11 no.2
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• pp.233-239
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• 2004

Anchovy soy sauce containing anchovy sauce was ripened in different vessels at 30$^{\circ}C$ for 4 months and measured in physical, chemical, microbiolgical and sensory quality attributes. The used vessels include glass, polypropylene (PP), polyethylene terephthalate (PET), stainless, and onggi (Korean earthenware) with 628 mL. Compared to the other vessels, onggi gave the highest moisture loss, maintained consistently higher microbial counts in total aerobic bacteria, lactic acid bacteria and yeasts, and attained high protease activity in the soy sauce product. Even with high moisture loss the onggi vessel did not produce the higher product salt content than the other vessels because there was salt diffusion outward through the container wall. All of these changes of the product in onggi resulted in lower pH, higher acidity and higher amounts of free amino acids and nucleotides after 4 month period, which was desirable for sensory quality.