• Journal of Soil and Groundwater Environment
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• v.10 no.4
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• pp.45-53
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• 2005

The objective of this study is to evaluate the effects of changes in soil temperature on biodegradation rate of diesel compounds from a field pilot test using hot air injection process. Total remediation time was estimated from in-situ biodegradation rate and temperature for optimum biodegradation. All tests were conducted by measuring in-situ respiration rates every about 10 days on highly contaminated area where an accidental diesel release occurred. The applied remediation methods were hot air injection/extraction process to volatilize and extract diesel compounds followed by a bioremediation process to degrade residual diesels in soils. Oxygen consumption rate varied from 2.2 to 46.3%/day in the range of 26 to $60^{\circ}C$, and maximum $O_2$ consumption rate was observed at $32.0^{\circ}C$. Zero-order biodegradation rate estimated on the basis of oxygen consumption rates varied from 6.5 to 21.3 mg/kg-day, and the maximum biodegradation rate was observed at $32^{\circ}C$ as well. In other temperature range, the values were in the decreasing trend. The first-order kinetic constants (k) estimated from in-situ respiration rates measured periodically were 0.0027, 0.0013, and $0.0006d^{-1}$ at 32.8, 41.1, and $52.7^{\circ}C$, respectively. The estimated remediation time was from 2 to 9 years, provided that final TPH concentration in soils was set to 870 mg/kg.

• Journal of Korea Water Resources Association
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• v.50 no.11
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• pp.715-723
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• 2017

Extracellular Polymeric Substances (EPS) in the water environment assemble fine, colloidal particles, such as clays, microorganisms and biomass, in large flocs, which are eventually subject to sedimentation and deposition and determine water/sediment quality and quantity. This study hence aimed to investigate the way that water and colloidal chemistry affects EPS-mediated flocculation of colloidal particles, using a jar-test experiment. Especially, ionic strength, divalent cation and humic substances concentrations were selected as experimental variables in the jar-test experiments, to elucidate their effects on EPS-mediated flocculation. A higher ionic strength increased flocculation capability, reducing electrostatic repulsion between EPS-attached colloidal particles and enhancing particle aggregation. 0.1 M NaCl ionic strength had higher flocculation capability, with 3 times larger floc size and 2.5 times lower suspended solid concentration, than 0.001 M NaCl. Divalent cations, such as $Ca^{2+}$, built divalent cationic bridges between colloidal particles and EPS (i.e., $colloid-Ca^{2+}-EPS$ or $EPS-Ca^{2+}-EPS$) and hence made colloidal particles to build into large, settelable flocs. A small $Ca^{2+}$ concentration enhanced flocculation capability, reducing suspended solid concentration 20 times lower than the initial dosed concentration. However, humic substances, adsorbed on colloidal particles, reduced flocculation, because they blocked EPS adsorption on colloidal particles and increased negative charges and electrostatic repulsion of colloidal particles. Suspended solid concentration in the tests with humic substances remained as high as the initial dosed concentration, indicating stabilization rather than flocculation. Findings about EPS-mediated flocculation in this research will be used for better understanding the fate and transport of colloidal particles in the water environment and for developing the best management practices for water/sediment quality.

• Clean Technology
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• v.27 no.4
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• pp.341-349
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• 2021

In combustion facilities, the nitrogen and sulfur in fossil fuels react with oxygen to generate air pollutants such as nitrogen oxides (NO_X) and sulfur oxides (SO_X), which are harmful to the human body and cause environmental pollution. There are regulations worldwide to reduce NO_X and SO_X, and various technologies are being applied to meet these regulations. There are commercialized methods to reduce NO_X and SO_X emissions such as selective catalytic reduction (SCR), selective non-catalytic reduction (SNCR) and wet flue gas desulfurization (WFGD), but due to the disadvantages of these methods, many studies have been conducted to simultaneously remove NO_X and SO_X. However, even in the NO_X and SO_X simultaneous removal methods, there are problems with wastewater generation due to oxidants and absorbents, costs incurred due to the use of catalysts and electrolysis to activate specific oxidants, and the harmfulness of gas oxidants themselves. Therefore, in this research, microbubbles generated in a high-pressure disperser and reducing agents were used to reduce costs and facilitate wastewater treatment in order to compensate for the shortcomings of the NO_X, SO_X simultaneous treatment method. It was confirmed through image processing and ESR (electron spin resonance) analysis that the disperser generates real microbubbles. NO_X and SO_X removal tests according to temperature were also conducted using only microbubbles. In addition, the removal efficiencies of NO_X and SO_X are about 75% and 99% using a reducing agent and microbubbles to reduce wastewater. When a small amount of oxidizing agent was added to this microbubble system, both NO_X and SO_X removal rates achieved 99% or more. Based on these findings, it is expected that this suggested method will contribute to solving the cost and environmental problems associated with the wet oxidation removal method.

• Journal of the Korean GEO-environmental Society
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• v.20 no.2
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• pp.41-48
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• 2019

Soil compaction is one of the most important activities in the area of civil works, including road construction, airport construction, port construction and backfilling construction of structures. Soil compaction, particularly in road construction, can be categorized into subgrade compaction and roadbed compaction, and is significant work that when done poorly can serve as a factor causing poor construction due to a lack of compaction. Currently, there are many different types of compaction tests, and the plate bearing test and the unit weight of soil test based on the sand cone method are commonly used to measure the degree of compaction, but many other methods are under development as it is difficult to secure economic efficiency. For the purpose of this research, a portable penetration meter called the Free-Fall Penetration Test (FFPT) was developed and manufactured. In this study, a homogeneous sample was obtained from the construction site and soil was classified through a sieve analysis test in order to perform grain size analysis and a specific gravity test for an indoor test. The principle of FFPT is that the penetration needle installed at the tip of an object put into free fall using gravity is used to measure the depth of penetration into the road surface after subgrade or roadbed compaction has been completed; the degree of compaction is obtained through the unit weight of soil test according to the sand cone method and the relationship between the degree of compaction and the depth of the penetration needle is verified. The maximum allowable grain size of soil is 2.36 mm. For $A_1$ compaction, a trend line was developed using the result of the test performed from a drop height of 10 cm, and coefficient of determination of the trend line was $R^2=0.8677$, while for $D_2$ compaction, coefficient of determination of the trend line was $R^2=0.9815$ when testing at a drop height of 20 cm. Free fall test was carried out with the drop height adjusted from 10 cm to 50 cm at increments of 10 cm. This study intends to compare and analyze the correlation between the degree of compaction obtained from the unit weight of soil test based on the sand cone method and the depth of penetration of the penetration needle obtained from the FFPT meter. As such, it is expected that a portable penetration tester will make it easy to test the degree of compaction at many construction sites, and will lead to a reduction in time, equipment, and manpower which are the disadvantages of the current degree of compaction test, ultimately contributing to accurate and simple measurements of the degree of compaction as well as greater economic feasibility.

• Journal of Korean Home Economics Education Association
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• v.33 no.3
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• pp.143-157
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• 2021

This study analyzed and verified the effects of a dietary education program for Korean young adults in single-person households. The dietary education program was conducted for five weeks (from November 10 to December 8, 2020) for Korean young adults in single-person households living in Seongbuk-gu, via four face-to-face education sessions and one online education session, including both theoretical lectures and practice. The effect of the dietary education program was analyzed through the Nutrition Quotient (NQ) questionnaire for adults provided by the Korean Nutrition Society, a dietary evaluation checklist questionnaire developed by the researchers, and photovoices. The average of 'Nutrition' score increased from 51.81 to 53.20, but there was no statistically significant difference. However, there was a significant change in the 'Moderation' category (p<0.05). As for the researcher-developed dietary evaluation, the average of the 'Importance' area rose from 3.77 to 3.99, but there was no statistically significant difference. The average of the 'Practice' area rose from 3.03 to 3.57, significant results were found (p<0.05). When the pre-/post-tests were compared by the sub-categories, four elements of 'Importance', i.e., balanced meals and avoided foods, and all five elements of 'Practice' were significantly improved (p<0.05). A total of 200 photovoices were analyzed according to Social Cognitive Theory. As a result of the analysis, the deterrents that help people eat healthy homemade food were 48% environmental factors, 30% behavioral factors, and 22% individual cognitive factors. The deterrents found to hinder participants from eating healthy homemade food were 72% environmental factors and 14% individual cognitive and behavioral factors. The results suggest that the dietary education program for Korean young adults in single-person households can be an effective tool that promotes self-motivation, behavioral changes, and improvements of the surrounding environment.

• Economic and Environmental Geology
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• v.54 no.2
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• pp.233-245
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• 2021

Many studies on the microstructures in rocks have been conducted using experimental methods with various equipment as well as natural rock studies to see the development of microstructures and understand their mechanisms. Grain boundary migration of mineral aggregates in rocks could cause grain growth or grain size changes during metamorphism or deformation as one of the main recrystallization mechanisms. This study suggests improved ways regarding the analog material experiments with reformed equipment to see sequential observations of these grain boundary migration. It can be more efficient than the existing techniques and carry out an appropriate microstructure analysis. This reformed equipment was implemented to enable optical manipulation by mounting polarizing plates capable of rotating operation on a stereoscopic microscope and a deformation rig capable of experimenting with analog materials. The equipment can automatically control the temperature and strain rate of the deformation rig by microcontrollers and programming and can take digital photomicrographs with constant time intervals during the experiment to observe any microstructure changes. The composite images synthesized using images by rotated polarizing plates enable us to see more accurate grain boundaries. As a rock analog material, norcamphor(C7H10O) was used, which has similar birefringence to quartz. Static grain growth and simple shear deformation experiments were performed using the norcamphor to verify the effectiveness of the equipment. The static grain growth experiments showed the characteristics of typical grain growth behavior. The number of grains decreases and the average grain size increases over time. These case experiments also showed a clear difference between the growth curves with three temperature conditions. The result of the simple shear deformation experiment under the medium temperature-low strain rate showed no significant change in the average grain size but presented the increased elongation of grain shapes in the direction of about 53° regarding the direction perpendicular to the shearing direction as the shear strain increases over time. These microstructures are interpreted as both the plastic deformation and the internal recovery process in grains are balanced by the deformation under the given experimental conditions. These experiments using the reformed equipment represent the ability to sequentially observe changing the microstructure during experiments as desired in the tests with the analog material during the entire process.

• Economic and Environmental Geology
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• v.54 no.3
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• pp.399-408
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• 2021

Natural soil was artificially contaminated with heavy metals (Cd, Pb, and Zn), and the movement of earthworm was characterized in real time using the ViSSET system composed of vibration sensor and the other components. The manifestation mechanism of ecological toxicity of heavy metals was interpreted based on the accumulative frequency of earthworm movement obtained from the real-time monitoring as well as the conventional indices of earthworm behavior, such as the change in body weight before and after tests and biocumulative concentrations of each contaminant. The results showed the difference in the earthworm movement according to the species of heavy metal contaminants. In the case of Cd, the earthworm movement was decreased with increasing its concentration and then tended to be increased. The activity of earthworm was severely increased with increasing Pb concentration, but the movement of earthworm was gradually decreased with increasing Zn concentration. The body weight of earthworm was proved to be greatly decreased in the Zn-contaminated soil, but it was similarly decreased in Cd- and Pb-contaminated soils. The bioaccumulation factor (BAF) was higher in the sequence of Cd > Zn > Pb, and particularly the biocumulative concentration of Pb did not show a clear tendency according to the Pb concentrations in soil. It was speculated that Cd is accumulated as a metallothionein-bound form in the interior of earthworm for a long time. In particular, Cd has a bad influence on the earthworm through the critical effect at its higher concentrations. Pb was likely to reveal its ecotoxicity via skin irritation or injury of sensory organs rather than ingestion pathway. The ecotoxicity of Zn seemed to be manifested by damaging the cell membranes of digestive organs or inordinately activating metabolism. Based on the results of real-time monitoring of earthworm movement, the half maximal effective concentration (EC50) of Pb was estimated to be 751.2 mg/kg, and it was similar to previously-reported ones. The study confirmed that if the conventional indices of earthworm behavior are combined with the results of newly-proposed method, the mechanism of toxicity manifestation of heavy metal contaminants in soils is more clearly interpreted.

• Journal of the Korean earth science society
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• v.41 no.6
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• pp.630-646
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• 2020

In rural areas, nitrate-nitrogen (NO3-N) pollution caused by agricultural activities is a major obstacle to the use of shallow groundwater as domestic water or drinking water. In this study, the water quality characteristics of shallow groundwater in Hyogyo-ri agricultural area of Yesan-gun, Chungcheongnam-do province was studied in connection with land use and chemical composition of soil layer. The average NO3-N concentration in groundwater exceeds the domestic and agricultural standard water qualities of Korea and is caused by anthropogenic sources such as fertilizer, livestock wastewater, and domestic sewage. The groundwater type mainly belongs to Ca(Na)-Cl type, unlike Ca-HCO3 type, a general type of shallow groundwater. The average NO3-N concentration (7.7 mg L-1) in groundwater in rice paddy/other (upstream, ranch, and residential) area is lower than the average concentration (22.8 mg L-1) in farm field area, due to a lower permeability in paddy area than that in farm field area. According to the trend analysis by the Mann-Kendall and Sen tests, the NO3-N concentration in the shallow groundwater shows a very weak decreasing trend with ~0.011 mg L-1yr-1 with indicating almost equilibrium state. Meanwhile, SO42- and HCO3- concentrations display annual decreasing trend by 15.48 and 13.15%, respectively. At a zone of 0 to 5 m below the surface, the average hydraulic conductivity is 1.86×10-5 cm s-1, with a greater value (1.03×10-4cm s-1) in sand layer and a smaller value (2.50×10-8 cm s-1) in silt layer.

• Economic and Environmental Geology
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• v.55 no.5
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• pp.477-495
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• 2022

This study examined the sustainability of CO₂-rich water by analyzing the water level and water quality change pattern with the amount of its use in Angseong area, Chungju. The origin and supply of CO₂ component were discussed in consideration of ⁸⁷Sr/⁸⁶Sr ratio, occurrence of CO₂-rich fluid inclusions in nearby W-Mo deposits and other surrounding geological characteristics. According to the data from 1986 to 2017, the depth of the water level of CO₂-rich water was significantly lowered in the late period (2009-2015) than in the early period (1986-1992) of the development of hot spa wells, and the optimal yields for pumping tests also showed a tendency to gradual decrease. Concentrations of CO₂ component also decreased continuously in the later stages compared to the early stages of development, but it has been stable since 2012. It is inferred that the geological environment related to forming W-Mo quartz vein deposits (0.5×1.5×several km) around the study area are largely involved in the origin and supply of CO₂ component, and the supply of CO₂ component is not infinitely supplied from deep current magma activity. Rather, since it is finitely supplied from a restricted subsurface region formed in the past geological period, it is necessary to efficiently control its use in order to maintain the sustainability of CO₂-rich water in the study area.

• Economic and Environmental Geology
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• v.56 no.1
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• pp.103-114
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• 2023

The Christian Museum of Gongju Jeil Church was first built in 1931 and was largely damaged during the Korean War, but the walls and chimneys have been preserved. This building has a high architectural values in that the chapel was reconstructed in 1956, and maintains its original form through repair of damaged parts rather than new construction. The stained glass windows were as installed in 1979 and has a great significance in the Dalle de Verre method using lump glass. However, some of the stained glass damaged partially, such as various cracks and splits, and vertical and horizontal cracks in the joint fillers of supporting the colored glass. As the structural materials of the stained glass window, an iron frame and cement mortar filled with it were used, and corrosion of iron, cracking of mortar and granular decomposition appear partially due to weathering. In the joint fillers, the content of Ca and S is very high, indicating that gypsum were used as admixtures, and the gypsums grow in a rhombohedral and forms a bundle, which is investigated to have undergone recrystallization. As a result of modeling the ultrasonic velocity at the joint fillers, the left and right windows at the entrance show relatively weak in the range of 800 to 1,600m/s, and the lower right corner of the altar window and the upper left corner of the center window were also 1,000 to 1,800m/s, showing relatively low physical properties. And gypsums produced during the neutralization of lime mortar were detected in the joint fillers and contaminants on the surface. Such salts may cause damage to the joint material due to freezing and thawing, so appropriate preventive conservation is required. Also, since various damage types are complexly appearing in stained glass window and joint filler, customized conservation treatment should be reviewed through clinical tests.