• Journal of Soil and Groundwater Environment
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• v.18 no.7
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• pp.25-31
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• 2013

Hydrogen peroxide takes much of the cost for Fenton reaction applied for treatment of organic contaminants. Therefore, the effective use of hydrogen peroxide makes the technology more cost effective. The effective use of hydrogen peroxide is especially needed in the soil and groundwater remediation where complete mixing is not possible and it takes a long time for reactive species to transport to the fixed target compounds. Stabilization ability for hydrogen peroxide of malonic acid was evaluated in Fenton and Fenton-like reactions in this study. Malonic acid contributes on the stabilization of hydrogen peroxide by weak interaction between iron and the stabilizer and inhibiting the catalytic role of iron. The stabilization effect increased as the solution pH decrease below the $pK_{a1}$. The stabilization effect increased as the concentration of malonic acid increased and the effect was maximized at the malonic acid concentration of about ten times higher than the iron concentration. The model organic contaminant was successfully oxidized in the presence of the stabilizer but the degradation rate was slower than the system without the stabilizer. The stabilization effect was also proved in a Fenton-like reaction where magnetite and hematite were used instead of soluble iron species.

• Journal of Biosystems Engineering
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• v.31 no.1 s.114
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• pp.9-15
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• 2006

Draft control is key technique in plow control system for automation of implement control system. To make the consistent draft force is an essential factor for preventing the reduction of working efficiency by tractor's slip and also improving the working efficiency. Therefore, the purpose of this study is to develop the draft sensor for draft control of plow and evaluate the usability of the algorithm of draft control system using proportional control valve. The developed draft control system could extract the draft force very well regardless of draft condition, change of setting draft force and response time in the response characteristic test. The maximum draft force at 3-Point linkage was 10,000 N and the deviation of the control system was 125.8 N in steady state condition. The developed control system worked very well with regard to the change of draft force in field and even in soil condition with soil reaction. The results of experiment showed the characteristics of response was sufficient to be used as the implement draft control system for tractor using proportional valve.

• Geotechnical Engineering
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• v.3 no.3
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• pp.21-30
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• 1987

Some methods are presented to estimate the ultimate lateral resistance of single active piles subjected to lateral loads above the ground surface, considering the lateral soil reaction, the pile length and the fixity condition of a pile head. The lateral soil reaction acting on a single active pile embedded in soil due to pile movement can be estimated by use of a theoretical equation which is derived by considering especially the plastic state of ground surrounding the pile and the pile- section shape. The piles are named short or long depending upon the relative magnitude of the induced bending moment to the yielding moment. As for the fixity condition of a pile head, the free head and the unrotated head are considered. Comparison with other experimental results gives that the calculated ultimate lateral resistance obtained by the author's theory is closer to experimental results than the one obtained by Brom's theory.

• Journal of Korean Society of Water and Wastewater
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• v.14 no.4
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• pp.318-327
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• 2000

Sludge production from water treatment plants is increasing each year because water resources deterioration is proceeding and water supply facilities are growing due to water demand increase. Water treatment plant sludges can be modified to soil cover in sanitary landfilling site through the lime treatment and other alternatives. The compression strength of $1.0kg/cm^2$ is necessary for the dozer operation on soft son cover material at municipal landfilling site. Modified sludge was experimentally produced in this study with lime, bentonite, loess, and activated loess dosing. X-ray diffraction patterns of the limed water treatment plant sludge confirmed the presence of calcium carbonate and ettringite. Unconfined compression strength properties of modified sludges showed material property improvement applicable for soil cover alternatives. When adding 20-30% activated loess to water treatment plant sludges. the modified sludges could reach the compression strength for cover soil after 7 days solidification reaction, but decrease of compression strength was intentioned in 28 days reaction period. Solidification effect of the modified sludge with activated loess was observed through the scanning electron microscope.

• Journal of Soil and Groundwater Environment
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• v.16 no.5
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• pp.18-23
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• 2011

The electrokinetic transport characteristics of salts were investigated using nitrate and sulfate accumulated saline greenhouse soil. Within 8 days, 95% of nitrate was removed from the soil, while sulfate removal was 19% for 8 days. The low removal of sulfate came from adsorption reaction on the soil particles or organic matter and precipitation with calcium. Divalent cations such as calcium and magnesium were transported toward cathode via electromigration, and most monovalent cation such as potassium was removed. The pattern of residual electrical conductivity was similar with that of sulfate. Based on the results, electrokinetic technique is effective to restore nitrate-accumulated saline soil, but is not effective to restore sulfate-accumulated soil.

• The Plant Pathology Journal
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• v.40 no.3
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• pp.282-289
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• 2024

Fire blight is a bacterial disease caused by Erwinia amylovora. In Korea, fire blight was first reported in 2015 in an orchard. If the infection is confirmed, all trees in the orchard must be removed and the orchard must remain closed for 3 years. Since 2020, if the number of trees infected with fire blight is less than 5% of the total trees in the orchard, only the infected tree and adjacent trees are removed in Korea. Three years after removal, the trees can be replanted after confirming that the orchard soil is free from E. amylovora. In this study, a protocol was established for detecting E. amylovora in soil via selective enrichment, using tryptic soy broth with 0.05% bile salts and 50 ㎍/ml cycloheximide, and real-time polymerase chain reaction. This protocol resulted in a 1,000-times improved detection limit for E. amylovora in soil samples compared to that in unenriched samples. Soil monitoring was performed for orchards where fire blight-infected trees had been removed 3-27 months prior; the selected orchards were monitored every 3 months. Monitoring confirmed that E. amylovora was not present in the soil at any site in any of the orchards. A new detection protocol facilitates the monitoring of E. amylovora in soil and could help permit the replanting of trees in orchards. Also monitoring results provide evidence that trees can be planted earlier.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.68-71
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• 2004

Effects of surfactants and natural organic matter (NOM) on the sorption and reduction of tetrachloroethylene (PCE) and chromate with iron were examined in this study. PCE and chromate reduction by iron depended on the ionic type of the surfactants in this study. The apparent reaction rate constants of PCE with Triton X-100 and hexadecyltrimethyl ammonium (HDTMA) at one half and two times of the critical micelle concentration (CMC) were relatively higher than without surfactants because of the enhanced PCE partitioning and surface concentration. In the presence of sodium dodecyl benzene sulfonate (SDDBS) at 2000 mg/L and NOM at 50 mg/L, the apparent reaction rate constants of PCE increased, but TCE production decreased. The enhanced removal rate of PCE was not due to the dechlorination, and the sorption was dominant iron with SDDBS and NOM. The apparent reaction rate constants of chromate by iron with Triton X-100 and NOM were 1.4-3.1 times lower than without surfactants while that with HDTMA was two times higher than without HDTMA, When the sorbed HDTMA molecules form admicelles, negatively-charged chromate has an affinity for the positively-charged HDTMA head group.

• Korean Journal of Environmental Agriculture
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• v.29 no.4
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• pp.402-407
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• 2010

Zerovalent iron (ZVI) is one of the most commonly used metallic reducing agents for the treatment of toxic contaminants in wastewater. Traditional ZVIs are less effective than nanoscale ZVI (nZVI) due to prolonged reaction time. However, the reactivity can be significantly increased by reducing the size of ZVI particles to nanoscale. In this study, nZVI particles were synthesized under laboratory condition and their efficiency in removing hexavalent chromium (Cr(VI)) from aqueous solutions were compared with commercially available ZVI particles. The results showed that the synthesized nZVI particles (SnZVI) reduced >99% of Cr(VI) at the application rate of 0.2% (w/v), while commercial nZVI (CnZVI) particles resulted in 59.6% removal of Cr(VI) at the same application rate. Scanning electron micrographs (SEM) and energy dispersive spectra (EDS) of the nZVI particles revealed the formation of Fe-Cr hydroxide complex after reaction. Overall, the SnZVI particles can be used in treating chromium contaminated wastewater.

• Geotechnical Engineering
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• v.8 no.2
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• pp.59-70
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• 1992

This work is to study experimentally the measurment of pore air pressure according to rainfall in colluvium model and the characteristics of pore water pressure according to increasement of artesian ground water head. After modeling a geological feature of the Tertiary formation, the experiment was performed about sixty times on three kinds of soil. This experimental results showed the variation of pore water and pore air pressures with time, the change of void ratio and appling pressure head in the nonsaturated soil. It can be also expressed by the final pore water and the air reaction ratios and then formularizing the relationship between the permeability coefficient and the void ratio. In the results of this experiment, the patterns of the pore water pressure reaction are classified by the step-type and the wave-type, and the time-lag to reach final point of pore water pressure is in order sand, sandy silt and clayey sand.

• Journal of Soil and Groundwater Environment
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• v.18 no.5
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• pp.39-45
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• 2013

Many researchers have studied the effectiveness of ultrasound in chemical and environmental engineering fields including material synthesis, pollutant removal, cleaning, extraction, and disinfection. Acoustic cavitation induced by ultrasound irradiation in aqueous phase can cause various sonophysical and sonochemical reactions without any chemicals. However most of the previous studies focused only on the relationships between ultrasonic conditions and the results of sonochemical reactions in lab-scale sonoreactors. As a results of this, only a few studies have been devoted to design and optimization of industrial scale sonoreactors. In this study, the effect of the distance between two opposite transducer modules on sonochemical reactions was investigated in single and dual irradiation systems (334 kHz) for four distances including 50, 100, 150, and 200 mm using KI dosimetry. It was found that the dual irradiation systems provided higher performance in terms of the zeroth reaction coefficient and the cavitation yield compared to the single irradiation systems. The sonochemiluminescence (SCL) images for the visualization of the cavitation field showed that cavitation active zone was larger and sonochemical reaction intensity was much higher in the dual irradiation system than in the single irradiation system.