• Journal of the Korean Geosynthetics Society
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• v.20 no.2
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• pp.23-33
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• 2021

In Korea, many reservoirs have been built for the purpose of solving the food shortage problem and supplying agricultural water. However, the current 75.6% of the reservoirs are in serious aged as more than 50 years have passed since the year of construction. In the case of such an aging reservoir, the stability due to scour and erosion inside the reservoir is very reduced, and if concentrated rainfall due to recent abnormal weather occurs, the aging reservoir may collapse, leading to a lot of damage to property and human life. Accordingly, each agency that manages aging reservoirs uses Ordinary Portland Cement (OPC) as an injection material and applies the grouting method. However, in the case of OPC, it may deteriorate over time and water leakage may occur again. And there are environmental problems such as consumption of natural resources and generation of greenhouse gases. So, there is a need to develop new materials and methods that can replace the OPC. In this study, an laboratory test and analysis were performed on the grout material developed to induce a curing reaction similar to that of OPC by recycling power plant byproduct. In addition, test in the field such as electric resistivity survey, Standard Penetration Test (SPT), and field permeability test were performed to analyzed to reinforcement effect and determine the possibility of using instead of OPC. As a results of the test, in the case of recycled power plant byproduct, the compressive strength was 2.9 to 3.2 times and the deformation modulus was 2.3 to 3.3 times higher, indicating that it is excellent in strength and can be used instead of OPC. And it was analyzed that the N value of the reservoir was increased by 1~2, and the coefficient of permeability (k) decreased to the level of 8.9~42.5%. showing sufficient reinforcing effect in terms of order.

• Journal of the Korean Applied Science and Technology
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• v.38 no.3
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• pp.824-831
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• 2021

1, 2-Octanediol galactoside (OD-gal) has been synthesized from 1, 2-octanediol (OD), as a safer cosmetic preservative, using recombinant Escherichia coli β-galactosidase (β-gal). To confirm the molecular structure of synthesized OD-gal, mass spectrometry and NMR (¹H- and ¹³C-) spectroscopy of OD-gal were carried out. In the reaction mixture, a sodium adduct ion of OD-gal (m/z=331.1732) was identified using mass spectrometry analysis. In addition, ¹H NMR spectrum of OD-gal showed multiple peaks corresponding to the galactosyl group, which is evidence of galactosylation on OD. Downfield proton peaks at δ_H 4.39 ppm and multiple peaks from δ_H 3.98~3.55 ppm were indicative of galactosylation on OD. Up field proton peaks at δ_H 1.52~1.26 ppm and 0.89 ppm showed the presence of CH₂ and CH₃ protons of OD. ¹³C NMR spectrum revealed the presence of 24 carbons suggestive of α- and β-anomers of OD-gal. Among 14 carbon peaks from each anomer, the 4 peaks at δ_C 31.4, 29.0, 22.3, and 13.7 ppm were assigned to be overlapped showing only 24 peaks out of a total of 28 peaks. The mass value from mass spectrometry analysis of OD-gal, and ¹H and ¹³C NMR spectral data were in good agreement with the expecting structure of OD-gal. Finally, we identified a galactose molecule from the hydrolysate of OD-gal using β-gal. We are expecting that through future study it will eventually be able to develop a safe cosmetic preservative.

• Microbiology and Biotechnology Letters
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• v.49 no.4
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• pp.519-527
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• 2021

In this study, the hemolysis of Enterococcus faecalis BMSE-HMP strains, isolated from human breast milk, was investigated, and the anti-hemolytic and antimicrobial effects on multidrug-resistant (MDR) bacteria were investigated. The enzyme activity of E. faecalis BMSE-HMP 4 strains was measured, and it was found that the activities of esterase and esterase lipase were the highest. In addition, no hemolytic reaction was observed in any of the isolates. Subsequently, the anti-hemolytic activity against MDR strains causing hemolysis was evaluated. E. faecalis BMSE-HMP002 had the highest anti-hemolytic activity against Staphylococcus aureus CCARM 3855 at 75.71 ± 10.00%. The anti-hemolytic activity against Escherichia coli DC 2 CCARM 0238 and Pseudomonas aeruginosa CCARM 0223 showed that the activity of BMSE-HMP001 was highest at 76.92 ± 2.99% and 87.93 ± 1.93%, respectively. Examination of the antimicrobial effects against the MDR bacteria Staphylococcus spp., Escherichia spp., Pseudomonas spp., Salmonella spp., Klebsiella spp., Enterobacter spp., and E. faecalis BMSE-HMP strains showed antimicrobial effects against both gram-positive and gram-negative strains. Breastfeeding delivers enterococci into the intestinal tract of newborns by lactation, and its usefulness is attracting attention as it has been reported that enterococci have a potential effect on neonatal immune development. In this study, the hemolytic and antimicrobial effects of E. faecalis BMSE-HMP strains on MDR bacteria were investigated, to confirm their potential as useful lactic acid bacteria. Additional studies on the antibiotic resistance and toxicity of the E. faecalis BMSE-HMP strains, isolated in this study, are necessary to prove it safe for use.

• Journal of Practical Agriculture & Fisheries Research
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• v.23 no.2
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• pp.63-70
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• 2021

In order to compare and investigate the growth rates of each of the various soils, the soil mixing ratios were varied to four soils (Pitmos, Pearlite, Masato, General Soil, and Cocopeat). Ten were selected for each soil ratio and the average length and weight were compared. As a result, in the ratio of No. 1 pitmos 6.5: Perlite 2: Masato 1.5, it was measured as 16.36cm, 0.60g. In the ratio of No. 2 pitmos 10, 13.74cm, 0.41g. In the ratio of No. 3 general clay 10, it was measured as 12.43cm, 0.26g. 4 general clay 8, 0.39g. The growth rate of each soil was measured to be superior to that of other soil growth environments in the ratio of pitmos 6.5: pearlite 2: masato 1.5 soil. For ginseng plant analysis, 30 ginseng plants grown in the average length and weight of each soil at a ratio of 6.5: pearlite 2: masato 1.5 and relatively low-result general soil were selected and analyzed. As a result, 1,040ppm of nitrite nitrogen(NO₃-N) was higher in ginseng plants grown in general soil. There was no significant difference in phosphoric acid(P), potassium(K), and magnesium(Mg). Ginseng is characterized by poor growth when it exceeds 300ppm by combining ammonia tae (NH₄-N) and nitrate tae (NO₃-N) nitrogen. In addition, nitric acid produced in a part of this nitrite makes the pH reaction of the soil acidic, and the nitrite remaining in the soil evaporates into gas.

• Journal of the Korean Institute of Gas
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• v.26 no.3
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• pp.45-53
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• 2022

In order to improve the emission of diesel engines, natural gas-diesel dual fuel combustion compression ignition engines are in the spotlight. In particular, a reactivity controlled compression ignition (RCCI) combustion strategy is investigated comprehensively due to its possibility to improve both efficiency and emissions. With advanced diesel direct injection timing earlier than TDC, it achieves spontaneous reaction with overall lean mixture from a homogeneous mixture in the entire cylinder area, reducing nitrogen oxides (NOx) and particulate matter (PM) and improving braking heat efficiency at the same time. However, there is a disadvantage in that the amount of incomplete combustion increases in a low load region with a relatively small amount of fuel-air. To solve this, sensitive control according to the diesel injection timing and fuel ratio is required. In this study, experiments were conducted to improve efficiency and exhaust emissions of the natural gas-diesel dual fuel engine at low load, and evaluate combustion stability according to the diesel injection timing at the operation point for power generation. A 6 L-class commercial diesel engine was used for the experiment which was conducted under a 50% load range (~50 kW) at 1,800 rpm. Two injectors with different spray patterns were applied to the experiment, and the fraction of natural gas and diesel injection timing were selected as main parameters. Based on the experimental results, it was confirmed that the brake thermal efficiency increased by up to 1.3%p in the modified injector with the narrow-angle injection added. In addition, the spray pattern of the modified injector was suitable for premixed combustion, increasing operable range in consideration of combustion instability, torque reduction, and emissions level under Tier-V level (0.4 g/kWh for NOx).

• Korean Journal of Plant Resources
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• v.35 no.5
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• pp.565-573
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• 2022

Gingival inflammation is one of the main causes that can be related to various periodontal diseases. Human gingival fibroblast (HGF) is the major constituent in periodontal connective tissue and secretes various inflammatory mediators, such as nitric oxide (NO) and prostaglandin E₂ (PGE₂), upon lipopolysaccharide stimulation. This study is aimed at investigating the anti-inflammatory and antioxidative activities of Lotus Root extract (LRE) in Porphyromonas gingivalis derived lipopolysaccharide (LPS-PG)-stimulated HGF-1 cells. The concentration of NO and PGE₂, as well as their responsible enzymes, inducible NO synthase (iNOS), and cyclooxygenase-2 (COX-2), was analyzed by Griess reaction, ELISA, and western blot analysis. LPS-PG sharply elevated the production and protein expression of inflammatory mediators, which were significantly attenuated by LRE treatment in a dose-dependent manner. LRE treatment also suppressed activation of Toll-like receptor 4 (TLR4)/myeloid differentiation primary response gene 88 (MyD88) and nuclear factor-κB (NF-κB) in LPS-PG-stimulated HGF-1 cells. In addition, one of phase II enzyme, NAD(P)H quinone dehydrogenase (NQO)-1, and its transcription factor, Nuclear factor erythroid 2-related factor 2 (Nrf2), were significantly induced by LRE treatment. Consequently, these results suggest that LRE ameliorates LPS-PG-induced inflammatory responses by attenuating TLR4/MyD88-mediated NF-κB, and activating NQO-1/Nrf2 antioxidant response element signaling pathways in HGF-1 cells.

• Clean Technology
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• v.28 no.4
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• pp.309-315
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• 2022

Research was conducted to derive the optimal operation conditions and the optimal cathode for using a DSA electrode as an anode to minimize electrode consumption during the removal of nitrogen from wastewater by the electro-chemical method. Of the various electrodes tested as cathodes, brass was determined to be the optimal electrode. It had the highest NO₃-N removal rate and the lowest concentration of residual NH₃-N, a by-product when Cl is present in the solution. Investigating the effect of current density found that when the initial concentration of NO₃-N was 50 mg L^-1, the optimal current density was 15 mA cm^-2. In addition, current densities above 15 mA cm^-2 did not significantly affect the NO₃-N removal rate. The effect of electrolytes on removing NO₃-N and minimizing NH₃-N was investigated by using Na₂SO₄ and NaCl as electrolytes and varying the reaction times. When Na₂SO₄ and NaCl are mixed at a ratio of 1.0 g L^-1 to 0.5 g L^-1 and reacted for 90 min at a current density of 15 mA cm^-2 and an initial NO₃-N concentration of 50 mg L^-1, the removal rate of NO₃-N was about 48% and there was no residual NH₃-N. On the other hand, when using only 1.5 g L^-1 of NaCl as an electrolyte, the removal rate of NO₃-N was the highest at about 55% and there was no residual NH₃-N.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.6
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• pp.1092-1099
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• 2022

Research on exhaust aftertreatment devices to reduce air pollutants and greenhouse gas emissions is being actively conducted. However, in the case of the particulate matters/nitrogen oxides (PM/NOx) simultaneous reduction device for ships, the problem of back pressure on the diesel engine and replacement of the filter carrier is occurring. In this study, for the optimal design of the integrated device that can simultaneously reduce PM/NOx, an appropriate standard was presented by studying the flow inside the device and change in back pressure through the inlet/outlet pressure. Ansys Fluent was used to apply porous media conditions to a diesel particulate filter (DPF) and selective catalytic reduction (SCR) by setting porosity to 30%, 40%, 50%, 60%, and 70%. In addition, the ef ect on back pressure was analyzed by applying the inlet velocity according to the engine load to 7.4 m/s, 10.3 m/s, 13.1 m/s, and 26.2 m/s as boundary conditions. As a result of a computational fluid dynamics analysis, the rate of change for back pressure by changing the inlet velocity was greater than when inlet temperature was changed, and the maximum rate of change was 27.4 mbar. This was evaluated as a suitable device for ships of 1800kW because the back pressure in all boundary conditions did not exceed the classification standard of 68mbar.

• Ecology and Resilient Infrastructure
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• v.9 no.2
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• pp.113-123
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• 2022

The blood and physiological changes of common carp (Cyprinus carpio) and crucian carp (Carassius auratus) were analyzed when the water temperature was rapidly increased from 20℃ (control) to 26 and 32℃. The water temperature reached 26℃ and 32℃ within 6 hours from the water temperature of 20℃, and the control was maintained at 20℃ for the duration of the experiment. From each experimental group, blood was collected every 3, 12, 24 and 48 hours after the water temperature rise, and the red blood cell count, hemoglobin, hematocrit, Na⁺, K⁺, Cl^-, cortisol, glucose, aspartate amino transferase (AST) and alanine amino transferase (ALT) contents were analyzed. In the case of the crucian carp experimental group where the water temperature was raised to 32℃, the concentrations of plasma cortisol, glucose, AST and ALT increased 3 hours after the water temperature rise, and the concentrations did not decrease until 48 hours (P<0.05). Plasma cortisol, glucose, AST, and ALT in both C. carpio and C. auratus in the control group and the experimental group raised to 26℃ increased at 3 hours after the water temperature rise (P<0.05), and decreased to the value before the water temperature rise at 48 hours (P<0.05). The plasma Na⁺, K⁺ and Cl^- concentrations of C. carpio and C. auratus in the experimental group where the water temperature was raised to 32℃ were higher than in the 20 and 26℃ experimental groups. The blood reaction of all experimental groups including the control group showed a common trend in both C. carpio and C. auratus increasing up to 12 hours after the water temperature rise and then decreasing at 48 hours after the water temperature rise. The results derived from this study would be useful for investigating the physiological response of fish stress in future. In addition, as fish mortality has recently occurred frequently in rivers and lakes, it is judged that it can be used as basic data.

• Journal of Wetlands Research
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• v.24 no.2
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• pp.83-92
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• 2022

The amount of the plastic waste has been increasing according to global demand for plastic. Microplastics are the most hazardous among all plastic pollutants due to their toxicity and unknown physicochemical properties. This study investigates the optimal methodology that can be applied to sewage samples for detecting microplastics before discussing reducing microplastics in MWTPs. In this study, the effect of different pretreatment methods while detecting microplastic analysis of MWTP influent samples was investigated; the samples were collected from the J sewage treatment plant. There are many pretreatment methods but two of them are widely used: Fenton digestion and hydrogen peroxide oxidation. Although there are many pretreatment methods that can be applied to investigate microplastics, the most widely used methods for sewage treatment plant samples are Fenton digestion and H₂O₂ oxidation. For each pretreatment method, there were factors that could cause an error in the measurement. To overcome this, in the case of the Fenton digestion pretreatment, it is recommended to proceed with the analysis by filtration instead of the density separation method. In the case of the H₂O₂ oxidation method, the process of washing with distilled water after the reaction is recommended. As a result of the analysis, the concentration of microplastics was measured to be 2.75ea/L for the sample using the H₂O₂ oxidation method and 3.2ea/L for the sample using the Fenton oxidation method, and most of them were present in the form of fibers. In addition, it is difficult to guarantee the reliability of measurement results from quantitative analysis performed via microscope with eyes. A calibration curve was created for prove the reliability. A total of three calibration curves were drawn, and as a result of analysis of the calibration curves, all R² values were more than 0.9. This ensures high reliability for quantitative analysis. The qualitative analysis could determine the series of microplastics flowing into the MWTP, but could not confirm the chemical composition of each microplastic. This study can be used to confirm the chemical composition of microplastics introduced into MWTP in the future research.