• Korean Journal of Soil Science and Fertilizer
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• v.34 no.1
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• pp.55-63
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• 2001

N fertilizer recommendations to optimize with consideration to maximum crop yields, maximum profits, and minimum N losses to ground or runoff water, an advisory system. Nitrogen Expert System (NES), was developed. The system was to estimate the optimal rate of N fertilizer application cornfields in Illinois. NES was constructed using Smart Elements, a knowledge-based system that manages the expertise of human experts. NES was reinforced by addition of the effect of a productivity index (PI), soil organic matter content (SOM), and pre-sidedressing of nitrate concentration (PSNT) to the optimal N fertilizer recommendation. NES contains 49 rules, 1 class, 14 objects, and 2 properties. NES was successfully operated, showing N recommendations with inputs of three soil properties including PI, SOM, and PSNT. NES can reduce N loss to the environment, but adherence to the recommendations may also reduce farmers income. Therefore, NES will be more effective by evaluating both environmental damage assessment and other economic agricultural management parameters and other soil physico-chemical parameters.

• Journal of Climate Change Research
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• v.8 no.3
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• pp.257-264
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• 2017

Carbon capture and storage (CCS) technology has been suggested as an ultimate strategy for mitigating climate change. However, potential leakage of $CO_2$ from the CCS facilities could lead to serious damage to environment. Plants can be a bio-indicator for $CO_2$ leakage as a cost-effective way, although plants' responses vary with plant species. In this study, a greenhouse experiment was conducted to investigate the relation between the $CO_2$ tolerance of corn species and the initial physiological responses to the elevated soil $CO_2$ concentration. Treatment groups included CI (99.99% $CO_2$ gas injection) and BI (no gas injection). Mean soil $CO_2$ concentration for the CI treatment was 19.5~39.4%, and mean $O_2$ concentration was 6.6~18.4%. The soil gas concentrations in the BI treatment were at the ambient levels. In the CI treatment, chlorophyll content was not decreased until the $13^{th}$ day of the $CO_2$ injection. On the $15^{th}$ day, leaf starch content and stomatal conductance were increased by 89% and 25% in the CI treatment compared to the BI treatment, respectively. This might be due to the compensatory reaction of corn to avoid high soil $CO_2$ stress. However, the prolonged $CO_2$ injection decreased chlorophyll content after 13 days. After $CO_2$ injection, plant biomass was reduced by 25% in the CI treatment compared to the BI treatment. Due to the inhibited root growth, leaf phosphorous and potassium contents were decreased by 54% on average in the CI treatment. This study indicates that corn has a high tolerance to soil $CO_2$ concentration of 30% for 2 weeks by its compensatory reactions such as an maintenance of chlorophyll content and an increase in stomatal conductance.

• Journal of the Korean Geotechnical Society
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• v.26 no.1
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• pp.45-54
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• 2010

It is important to calculate the natural frequency of a piled structure in the design stage in order to prevent resonance-induced damage to the pile foundation and analyze the dynamic behavior of the piled structure during an earthquake. In this paper, a simple but relatively accurate method employing a mass-spring model is presented for the evaluation of the natural frequency of a pile-soil system. Greatly influencing the calculation of the natural frequency of a piled structure, the spring stiffness between a pile and soil was evaluated by using the coefficient of subgrade reaction, the p-y curve, and the subsoil elastic modulus. The resulting natural frequencies were compared with those of 1-g shaking table tests. The comparison showed that the natural frequency of the pile-soil system could be most accurately calculated by constructing a stiffness matrix with the spring stiffness of the Reese (1974) method, which utilizes the coefficient of the subgrade reaction modulus, and Yang's (2009) dynamic p-y backbone curve method. The calculated natural frequencies were within 5% error compared with those of the shaking table tests for the pile system in dry dense sand deposits and 5% to 40% error for the pile system in saturated sand deposits depending on the occurrence of excess pore water pressure in the soil.

• Nuclear Engineering and Technology
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• v.55 no.4
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• pp.1460-1467
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• 2023

A robust approach was conducted to determining the absolute oral bioavailable (f_ab) fractions of ²³⁸U and ²³²Th in rats exposed to contaminated soil along with their hematotoxicity and nephrotoxicity. The soil sample is the International Atomic Energy Agency-312 (IAEA-312) certified reference material, whereas blood, bones, and kidneys of in vivo female Sprague-Dawley (SD) rats estimate ²³⁸U- and ²³²Th-f_ab fractions post-exposure. We predict the bioavailable concentration (C_ab) and f_ab values of ²³⁸U and ²³²Th after acute soil ingestion. The blood ²³⁸U (0.750%) and ²³²Th (0.028%) reach their maximum f_ab values after 48 h. The ²³⁸U (f_ab: 0.169-0.652%) accumulates mostly in the kidney, whereas the ²³²Th (f_ab: 0.004-0.021%) accumulates primarily in the bone. Additionally, ²³⁸U is more bioavailable than ²³²Th. Post 48 h acute ingestion demonstrates noticeable histopathological and hematological alterations, implying that intake of ²³⁸U in co-contaminated soil can lead to erythrocytes and proximal tubules damage, whereas, ²³²Th intake can harm erythrocytes. Our study provides new directions for future research into the health implications of acute oral exposures to ²³⁸U and ²³²Th in co-contaminated soils. The findings offer significant insight into the utilization of in vivo SD rat testing to estimate ²³⁸U and ²³²Th bioavailability and toxicity in exposure assessment.

• The Journal of Engineering Geology
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• v.33 no.4
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• pp.555-571
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• 2023

Due to South Korea's concentrated summer rainfall, constituting 70% of the annual total, landslides frequently occur during the rainy season, necessitating accurate prediction methods to mitigate associated damage. In this study, a reduced-scale and full-scale slope was configured using weathered granite soil to find the possibility of establishing measurement management criterias through landslide reproduction. The experiment focused on matric suction, analyzing changes in ground properties and failure patterns caused by rainfall infiltration. Subsequently, an unsaturated infinite slope stability analysis was conducted. By calculating the failure time when the safety factor falls below 1 for each experiment, landslide prediction was demonstrated to be possible, approximately 17 minutes prior for the reduction-scale experiment and 6.5 hours for the full-scale experiment. These findings provide useful data for establishing Korean soil slope measurement management criteria that consider the characteristics of weathered granite soil.

• Journal of the Korean GEO-environmental Society
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• v.25 no.6
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• pp.5-12
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• 2024

Currently, a grouting method that minimizes damage to the reservoir embankment by injecting solidification agent at low pressure is commonly used to ensure waterproofing and safety of the embankment, but the use of solidification agents can cause issues, such as a decrease in durability and a lack of clear method for determining the mixing ratio. In this study, when the base ground and solidification agent were stirred and mixed at various weight mixing ratios, the permeability coefficient and strength of the mixture were confirmed through laboratory tests, and the optimal mixing ratio was suggested through analysis of the test results. The specimen for the laboratory test was produced considering the mixing ratio of the solidification agent. The specimen for the permeability coefficient test was tested by producing one each of cohesionless and cohesive soil for a mixing amount of 1.5 kN/m³ of solidification agent, and the permeability test results confirmed that the water barrier performance was secured below the permeability coefficient value required by various design criteria. A total of 24 specimens for the strength test were produced, 3 for each of 5 mixing amounts for cohesive soil and 3 mixing amounts for cohesionless soil. The strength test results showed that the uniaxial compressive strength tends to increase linearly with increasing curing time for both cohesionless soil and cohesive soil when the mixing amount is less than 2.0 kN/m³. Therefore, the optimal mixing ratio applied to the site is determined to be mixing amount of 1.5 kN/m³ and 2.0 kN/m³. Finally, numerical analysis reflecting test results was conducted on design case for improvement projects for aging reservoirs embankment to verify the water barrier performance and safety improvement effects.

• 한국방재학회:학술대회논문집
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• 2007.02a
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• pp.238-241
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• 2007

The forest seemed apparently to die on the forest fire area in Honjima, Kagawa Prefecture, Japan. However, the soil that became growing basic of vegetation hardly suffered damage, and the forest recovery was started by the sprout, etc. in the next year. For restoration of forest fire area, the fascine mulching works and log barrier works using the damaged trees were used for the upper-stream, and chack dam and erosion control dam were set up in the downstream. Also, the forest restoration was tried with the plants and the microorganism that inhabit in Honjima to preserve a peculiar forest ecosystem.

• Journal of the Korean Professional Engineers Association
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• v.19 no.2
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• pp.21-25
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• 1986

Structure-borne noise due to forced vibration which is originated from subway operation and transmitted to buildings in order of rail-wood tie-concrete bed-structure-soil-building foundations-members of building results in social problem of environmental pollution. Moreover this becomes a serious problem because of the increment of surface traffic and subway operation made by meeting traffic system in crowded cities. Since subway is constructed along the principal road or through the residential area and as the worst case may be, building foundations is contact with top part of subway structure, it is possible that vibration resonance results in fatal damage of buildings. And, structure-borne vibration noise due to subway operation at late and early hours have the residents suffer from insonmia, restlessness and so on. Therefore, to satisfy the future need concerning the environmental protection, this report deals with the influence of structure-borne vibration noise on the basis of the characteristics of Seoul Subway System.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.929-934
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• 2001

As the notion of environment protection changes throughout the world, construction engineers, as part of the effort to resolve environmental problems, have been actively doing research on environmental friendly porous concrete using large and non-uniform aggregate. Concrete having a great deal of continuous porosity enable water and air to pass freely through firmly hardened material, allowing necessary nutrients to reach roots of vegetation, thereby sustaining them. It is possible to prevent the exhaustion of natural resources by recycling waste concrete and industrial by-products, to reduce damage caused by the destruction of nature through effective management of natural resources, to preserve the natural environment and vegetation in urban areas by activating the soil, protecting the underground ecology system, and growing garden plants through the application of environmentally friendly concrete.

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 2001.05a
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• pp.129-129
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• 2001

1,2-Dibromo-3-chloropropane (DBCP), a soil fumigant against nematodes, is a genotoxic carcinogen and also is classified by World Wildlife Fund as endocrine disruptors. DBCP has been extensively studied on genotoxicity, carcinogenicity, and damage in male reproductive-related organs. However, information on precise mechanism of mutagenesis and carcinogenesis of DBCP is yet unknown. (omitted)