• 한국환경복원기술학회지
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• 제9권1호
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• pp.72-88
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• 2006

The optimal environmental ranges of the establishment phase for the distribution of Zizania latifolia and Typha angustifolia was determined to develop a set of basic data and criteria of planting substrate for the restoration, conservation and management of wetlands. The study was carried at 17 wetlands in the Kyunggi-do and Gyeongsangnam-do region where inland wetlands place intensively in June, 2005. Total 127 quadrats were sets in growing areas of Zizania latifolia and Typha angustifolia. $NO_3-N$, K, Ca, Mg and Na in the water variables and soil texture, LOI (loss on ignition), soil pH and soil conductivity in the soil variables were analyzed. The optimal range of water depth for the distribution of Zizania latifolia was -5~39cm, $NO_3-N$ content of water was <0.01~0.19ppm, K content of water was 0.1~5.9ppm, Ca content of water 0.5~44.9ppm, Mg content of water was 1.2~11.9ppm, Na content of water 3.4~29.9ppm, water conductivity was 48~450${\mu}S$/cm, respectively. The optimal range of LOI for the distribution of Zizania latifolia was 1.7~11.9%, soil conductivity was 25.5~149.9${\mu}S$/cm, respectively. The optimal range of water depth for the distribution of Typha angustifolia was -20~24cm, $NO_3-N$ content of water was <0.01~0.19ppm, K content of water was 0.2~2.9ppm, Ca content of water 0.6~19.9ppm, Mg content of water was 0.2~5.9ppm, Na content of water 3.5~19.9ppm, water conductivity was 96~450${\mu}S$/cm, respectively. The optimal range of LOI for the distribution of Typha angustifolia was 2.4~15.9%, soil conductivity was 17.6~149.9${\mu}S$/cm, respectively. The optimal soil texture were loam, silt loam and sandy loam in both species. The lower water depth (-20~40cm) is appropriate to increase biodiversity in both species dominated community and it is better to maintain water depth of 40~100cm for water purification. Both species appear frequently in the soil with high silt content.

• 한국수소및신에너지학회논문집
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• 제27권6호
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• pp.712-720
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• 2016

When bioethanol and water are mixed at a proper ratio, phase separation can occur because of the immiscibility of biobutanol with water. Phase separation in bioethanol blends fuels is a major problem for gasoline vehicle users due to effect of octane number and component corrosion. Thus, in this study, the phase separation of bioethanol was examined effect of bioethanol blends (E3 (3 vo.% bioethanol in gasoline), E5 and E10) in presence of water. The effect were evaluated behavior with phase separation test, simulation test of fuel tank in gas station according to water addition volume and it was investigated change of water content, bioethanol content and octane number for gasoline phase in bioethanol blends (E3, E5 and E10) every 1 week after water addition. The E3 occurred phase separation more easily than the E5 and E10 in small water contents because solubility of water on ethanol content difference in gasoline-ethanol. It was kept a initial level of water content, bioethanol content, and octane number by repeated sample replacing in simulation test of fuel tank.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 가을학술발표대회논문집
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• pp.173-174
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• 2023

In this study, unit-water content was measured using a frequency domain reflecometry(FDR) sensor that complements the problems of the existing unit-water content measurement method to evaluate the unit-water content affecting the workability, durability, and quality of high strength concrete. The experiment used the unit-water content of high strength concrete as a variable, and the accuracy and probability distribution of the unit-water content measured through deep learning were analyzed for the output value output through the FDR sensor. In the case of the unit-water content predicted by deep learning analysis, a high accuracy and high distribution of more than 93% were found within the error range of ± 10 kg/m³. In the future, research is needed to secure high reliability by utilizing data obtained through experiments with various variables.

• 한국환경복원기술학회지
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• 제7권6호
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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.

• Geomechanics and Engineering
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• 제31권5호
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• pp.519-527
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• 2022

Shear failure in soil is the primary cause of most geotechnical structure failures or instability. Soil water content is a significant factor affecting soil shear strength. In this study, the shear strength of samples with different water contents was tested. The shear strength, cohesion, and internal friction angle decreased with increasing water content. Based on the variation of cohesion and internal friction angle, the water content zone was divided into a high-water content zone and low-water content zone with a threshold water content of 15.05%. Cohesion and internal friction angle have a good linear relationship with water content in both zones. Environmental Scanning Electron Microscopy (ESEM) test presented that the aggregates size of the compacted loess gradually increases with increasing water content. Meanwhile, the clay in the compacted loess forms a matric that envelops around the surface of the aggregates and fills the inter-aggregates pores. A quantitative analysis of bound water and free water under different water contents using a nuclear magnetic resonance (NMR) test was carried out. The threshold water content between bound water and free water was slightly below the plastic limit, which is consistent with the results of shear strength parameters. Combined with the T2 distributions obtained by NMR, one can define a T2 relaxation time of 1.58 ms as the boundary point for bound water distribution without free water. Finally, the effects of bound water and free water on shear strength parameters were analyzed using linear regression analysis.

• 한국축산식품학회지
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• 제40권6호
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• pp.969-979
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• 2020

Fresh grass carp was used to produce surimi and 50 g/kg, 100 g/kg, or 150 g/kg pork back fat was added. The water distribution, thiobarbituric acid reactive substances (TBARS), myoglobin oxidation, color parameter (L*, a*, and b*), heme and non-heme iron content of samples were determined to analyze the effects of different fat content on the oxidation of myoglobin and lipids during multiple freeze-thaw cycles of grass carp surimi. Both multiple freeze-thaw cycles and increased fat content lead to an increase in TBARS, a blue shift in the absorption peak of myoglobin porphyrin, a decrease in heme iron content, and an increase of non-heme iron content. Repeated freeze-thaw caused a decrease in immobilised water content and L*, and caused an increase in a* and b*. Increased fat content caused an increase in immobilised water content, L* and a*, and caused a decrease in b*.

• Structural Engineering and Mechanics
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• 제80권5호
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• pp.523-538
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• 2021

The mechanical behaviour and stability of coal mining engineering underground is significantly affected by ground water. In this study, nuclear magnetic resonance imaging (NMRI) technique was employed to determine the water distribution characteristics in coal specimens during saturation process, based on which the functional rule for water distribution was proposed. Then, using discrete element method (DEM), an innovative numerical modelling method was developed to simulate water-weakening effect on coal behaviour considering moisture content and water distribution. Three water distribution numerical models, namely surface-wetting model, core-wetting model and uniform-wetting model, were established to explore the water distribution influences. The feasibility and validity of the surface-wetting model were further demonstrated by comparing the simulation results with laboratory results. The investigation reveals that coal mechanical properties are affected by both water saturation coefficient and water distribution condition. For all water distribution models, micro-cracks always initiate and nucleate in the water-rich area and thus lead to distinct macro fracture characteristics. With the increase of water saturation coefficient, the failure of coal tends to be less violent with less cracks and ejected fragments. In addition, the core-wetting specimen is more sensitive to water than specimens with other water distribution models.

• Geomechanics and Engineering
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• 제24권5호
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• pp.419-430
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• 2021

Investigation on the compressibility and shear strength of compacted loess is of great importance for the design and operation of engineering infrastructures in filling area. In this study, the mechanical behaviors of Yan'an compacted loess are investigated at various dry densities and water contents by conducting one dimensional compression and direct shear tests. And the elastic compressibility, plastic compressibility, yield stress and strength are obtained from the experiments. Results show that when water content increases, plastic compressibility parameter increases, but yield stress decreases. However, the increase of dry density leads to a decrease in plastic compressibility parameter but an increase in yield stress. In addition, elastic compressibility parameter is found to be a constant which is irrelevant to water content and dry density. As for strength, cohesion and internal friction angle is directly proportional to dry density, but inversely proportional to water content. Moreover, the mercury intrusion porosimetry (MIP) and scanning electron microscope (SEM) tests were also performed to observe the pore size distribution and microstructure of the specimens. Finally, by using results of MIP and SEM tests, the compressibility and strength behaviours of Yan'an compacted loess are explained from the perspective of pore-size distribution and microstructure.

• 한국임상수의학회지
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• 제15권1호
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• pp.156-161
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• 1998

This study investigated the microbiological changes and distribution of bacteria producing enzyme in order to change food wastes to animal feed during 6 days at room temperature. Food wastes were divided as follows: one is untreated food wastes containing 80% water content and another wastes containing 40% water content adiusted by wheat bran. During the fermentation of food wastes, Lactobacillus sp. and Streptococcus sp. were grown the top position among investigated microorganisms in both of food wastes. Numbers of total microorganisms were much more than untreated wastes during fermentation of flood wastes with 40% water content. But, Streptococcus sp. and Enterobacteriaceae from 4 to 6 days were not detected in treated wastes with 40% water contents. This fact indicated that the adiustment of water content in food waste was effective in fermentation. However, the numbers of microorganisms producing pretense were low in both treated and untreated food wastes. These results suggested that flood wastes should be treated as food wastes with 40% water content to maintain a lot of fermentative microorganisms such as Lactobacillus sp., Streptococcus sp. and yeasts together with pretense to make final animal feed.

• Ocean and Polar Research
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• 제37권1호
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• pp.23-35
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• 2015

A 450 m-long sediment section was recovered from Hole U1359D located at the eastern levee of the Jussieau submarine channel on the Wilkes Land continental rise (East Antarctica) during IODP Expedition 318. The age model for Hole U1359D was established by paleomagnetic stratigraphy and biostratigraphy, and the ages of core-top and core-bottom were estimated to be about 5 Ma and 13 Ma, respectively. Biogenic opal content during this period varied between 3% and 60%. In the Southern Ocean, high biogenic opal content generally represents warm climate characterized by the increased light availability due to the decrease of sea-ice distribution. The surface water productivity change in terms of biogenic opal content at about 10.2 Ma in the Wilkes Land continental rise was related to the development of Northern Component Water. After about 10.2 Ma, more production of Northern Component Water in the North Atlantic caused to increase heat transport to the Southern Ocean, resulting in the enhanced diatom production. Miocene isotope events (Mi4~Mi7), which are intermittent cooling intervals during the Miocene, appeared to be correlated to the low biogenic opal contents, but further refinement was required for precise correlation. Biogenic opal content decreased abruptly during 6 Ma to 5.5 Ma, which most likely corresponds to the Messinian salinity crisis. Short-term variation of biogenic opal content was related to the extent of sea-ice distribution associated with the location of Antarctic Polar Front that was controlled by glacial-interglacial paleoclimate change, although more precise dating and correlation will be necessary. Diatom production in the Wilkes Land continental rise increased during the interglacial periods because of the reduced sea-ice distribution and the southward movement of Antarctic Polar Front.