• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.371-374
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• 2005

We accomplished optimization for pump and treat (P&T) designs in consideration of degradation processes such as retardation and biodegradation, which are significant for contaminant fate in hydrogeology. For more desirable remediation, optimal pumping duration and minimum pumping rate constraint problems are studied. After a specific P&T duration, it replaces the P&T with the enhanced natural attenuation (ENA), which induces aerobic biodegradation by maintaining oxygen concentration. The design in this strategy carries out the optimization for the number and locations of oxygen injection wells.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.164-167
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• 2004

To investigate the chemical and microbiological characteristics of groundwater and surface waters in contaminated sites, hydrochemical and microbial community analysis were executed. Different indigenous bacteria were observed at 4 contaminated sites and this is considered to decompose the contaminants of groundwater. The research results showed the close relationship between hydrochemistry and microbial characteristics and those are used for the information of natural attenuation and enhanced bioremediation.

• Journal of Korean Society on Water Environment
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• v.40 no.1
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• pp.11-18
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• 2024

Recently, enhanced in situ bioremediation using slow substrate release techniques has been actively researched for managing TCE-contaminated groundwater. This study conducted a lab-scale batch reactor experiment to evaluate the feasibility of natural attenuation for TCE dechlorination using microsized corn-oil droplet (MOD) as an activator considering the following three factors: 1) TCE dechlorination in the presence or absence of MOD; 2) TCE dechlorination in the presence or absence of inactivator of native microbial activity; and 3) MOD concentration effects on TCE dechlorination. Batch reactors were constructed using site groundwater and soil in which Dehalococcoides bacteria were present. Without MOD, TCE was decomposed into dichloroethylene (DCE). However, other by-products of TCE dechlorination were not detected. With MOD, DCE, vinyl chloride (VC), and ethylene (ETH) were sequentially observed. This result confirmed that MOD effectively supplied electrons to complete dechlorination of TCE to ETH. However, when an excess of MOD was provided, it formed unfavorable conditions for anaerobic digestion because dechlorination reaction did not proceed while propionic acid was accumulated after DCE was generated. Therefore, if an appropriate amount of MOD is supplied, MOD can be effectively used as a natural reduction activator to promote biodegradation in an aquifer contaminated by TCE.

• Korean Journal of Environmental Agriculture
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• v.33 no.2
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• pp.134-137
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• 2014

BACKGROUND: Dissipation of herbicides in paddy water varies significantly, being dependent on environmental conditions such as sunlight. The photodegradation under natural sunlight may be one of natural degradation routes of herbicides dissipation. Therefore, the aim of this study was to monitor the degradation of butachlor and pyrazosulfuron-ethyl in paddy water under natural sunlight. METHODS AND RESULTS: The 12 water sample bottles of treatment were covered by quart glass plates, which allow about 90% of UV radiation (280-2000 nm) to pass through, to minimize the UV attenuation. The other 12 water sample bottles of the control were covered by glass lids and wrapped with aluminum foils to prevent the sunlight. The concentration of butachlor and pyrazosulfuron-ethyl in paddy water samples bottles was monitored under ambient conditions with and without natural sunlight. The concentration of butachlor and pyrazosulfuron-ethyl for treatment decreased from $355.3{\mu}g/L$ to $37.8{\mu}g/L$ and from $10.5{\mu}g/L$ to $3.9{\mu}g/L$, respectively, during consecutive 21 days after herbicide application under natural sunlight. CONCLUSION: The concentration of butachlor in paddy water decreased quickly under ambient conditions with natural sunlight. The degradation of butachlor in paddy water was enhanced by the natural sunlight. However, the degradation of pyrazosulfuron-ethyl was insignificant under natural sunlight.

• Structural Engineering and Mechanics
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• v.87 no.4
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• pp.297-304
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• 2023

Targeted introduction of explosion-resisting and energy-absorbing materials and optimization of explosion-resisting composite structural styles in underground engineering are the most important measures for modern engineering protection. They could also improve the survivability of underground engineering in wartime. In order to test explosion-resisting and energy-absorbing effects of high-performance equal-sized-aggregate (HPESA) concrete, the explosive loading tests were conducted on HPESA concrete composite plates by field simple explosion craters. Time-history curves of the explosion pressure at the interfaces were obtained under six conditions with different explosion ranges and different thicknesses of the HPESA concrete plate. Test results show that under the same explosion range, composite plate structures with different thicknesses of the HPESA concrete plate differ significantly in terms of the wave-absorbing ability. Under the three thicknesses in the tests, the wave-absorbing ability is enhanced with the growing thickness and the maximum pressure attenuation index reaches 83.4%. The energy attenuation coefficient of the HPESA concrete plate under different conditions was regressively fitted. The natural logarithm relations between the interlayer plate thickness and the energy attenuation coefficient under the two explosion ranges were attained.

• Plant Biotechnology Reports
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• v.4 no.4
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• pp.243-251
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• 2010

Nitric oxide (NO) has been shown to be involved in diverse physiological processes in microbes, animals and plants. In this study, the involvement of NO in the development and possible roles in oxidative stress protection of Chinese cabbage (Brassica rapa subsp. pekinensis cv. Samrack-ulgari) seedlings were investigated. Exogenous application of sodium nitroprusside (SNP) retarded root elongation, while increasing lateral root formation of Chinese cabbage. Plants showed no signs of external stress due to SNP application in true leaves. Cotyledons of 3-week-old Chinese cabbage plants were found to be highly sensitive to SNP application. Treated cotyledons displayed rapid tissue collapse and associated cell death. Although SNP application reduced root growth under normal growth conditions, it also enhanced methyl viologen (MV)-mediated oxidative stress tolerance. Analysis of SNP application to Chinese cabbage leaf disks, revealed SNP-induced tolerance against oxidative stresses by MV and $H_2O_2$, and evidence includes prevention of chlorophyll loss, superoxide anion (${O_2}^-$) accumulation and lipid peroxidation. This report supports a role for nitric oxide in modulating early seedling development, programmed cell death and stress tolerance in Chinese cabbage.

• Korean Journal of Remote Sensing
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• v.38 no.1
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• pp.83-101
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• 2022

Accurate atmospheric correction is essential for the analysis of land surface and environmental monitoring. Aerosol optical depth (AOD) information is particularly important in atmospheric correction because the radiation attenuation by Mie scattering makes the differences between the radiation calculated at the satellite sensor and the radiation measured at the land surface. Thus, it is necessary to use high-quality AOD data for an appropriate atmospheric correction of high-resolution satellite images. In this study, we examined the Second Simulation of a Satellite Signal in the Solar Spectrum (6S)-based atmospheric correction results for the Sentinel-2 images in South Korea using raster AOD (MODIS) and single-point AOD (AERONET). The 6S result was overall agreed with the Sentinel-2 level 2 data. Moreover, using raster AOD showed better performance than using single-point AOD. The atmospheric correction using the single-point AOD yielded some inappropriate values for forest and water pixels, where as the atmospheric correction using raster AOD produced stable and natural patterns in accordance with the land cover map. Also, the Sentinel-2 normalized difference vegetation index (NDVI) after the 6S correction had similar patterns to the up scaled drone NDVI, although Sentinel-2 NDVI had relatively low values. Also, the spatial distribution of both images seemed very similar for growing and harvest seasons. Future work will be necessary to make efforts for the gap-filling of AOD data and an accurate bi-directional reflectance distribution function (BRDF) model for high-resolution atmospheric correction. These methods can help improve the land surface monitoring using the future Compact Advanced Satellite 500 in South Korea.

• Journal of Nutrition and Health
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• v.56 no.6
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• pp.589-601
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• 2023

Purpose: Baicalein, a natural flavone found in herbs, exhibits diverse biological activities. Nonalcoholic steatohepatitis (NASH) is an irreversible condition often associated with a poor prognosis. This study aimed to evaluate the effects of baicalein on the development of NASH in mice. Methods: Male C57BL/6J mice were randomly divided into four groups. Three groups were fed a methionine-choline-deficient (MCD) diet to induce NASH and were simultaneously treated with baicalein (at doses of 50 and 100 mg/kg) or vehicle only (sodium carboxymethylcellulose) through oral gavage for 4 weeks. The control group was fed a methionine-choline-sufficient (MCS) diet without the administration of baicalein. Results: The baicalein treatment significantly reduced serum levels of alanine aminotransferase and aspartate aminotransferase, suggestive of reduced liver damage. Histological analysis revealed a marked decrease in nonalcoholic fatty liver activity scores induced by the MCD diet in the mice. Similarly, baicalein treatment at both doses significantly attenuated the degree of hepatic fibrosis, as examined by Sirius red staining, and hepatocellular death, as examined by the terminal deoxynucleotidyl transferase dUTP nick end labeling assay. Baicalein treatment attenuated MCD-diet-induced lipid peroxidation, as evidenced by lower levels of hepatic malondialdehyde and 4-hydroxynonenal, demonstrating a reduction in oxidative stress resulting from lipid peroxidation. Moreover, baicalein treatment suppressed hepatic protein levels of 12-lipoxygenase (12-Lox) induced by the MCD diet. In contrast, baicalein enhanced the activities of antioxidant enzymes such as superoxide dismutase, catalase, and glutathione peroxidase. Additionally, baicalein treatment significantly reduced hepatic non-heme iron concentrations and hepatic ferritin protein levels in mice fed an MCD diet. Conclusion: To summarize, baicalein treatment suppresses hepatic lipid peroxidation, 12-Lox expression, and iron accumulation, all of which are associated with the attenuation of NASH progression.