• Advances in nano research
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• v.12 no.5
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• pp.515-527
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• 2022

The application of fibers in concrete obviously enhances the properties of concrete, also the application of natural fibers in concrete is raising due to the availability, low cost and environmentally friendly. Besides, predicting the mechanical properties of concrete in general and shear strength in particular is highly significant in concrete mixture with fiber nanocomposite reinforced concrete (FRC) in construction projects. Despite numerous studies in shear strength, determining this strength still needs more investigations. In this research, Adaptive Neuro-Fuzzy Inference System (ANFIS) have been employed to determine the strength of reinforced concrete with fiber. 180 empirical data were gathered from reliable literature to develop the methods. Models were developed, validated and their statistical results were compared through the root mean squared error (RMSE), determination coefficient (R²), mean absolute error (MAE) and Pearson correlation coefficient (r). Comparing the RMSE of PSO (0.8859) and ANFIS (0.6047) have emphasized the significant role of structural parameters on the shear strength of concrete, also effective depth, web width, and a clear depth rate are essential parameters in modeling the shear capacity of FRC. Considering the accuracy of our models in determining the shear strength of FRC, the outcomes have shown that the R² values of PSO (0.7487) was better than ANFIS (2.4048). Thus, in this research, PSO has demonstrated better performance than ANFIS in predicting the shear strength of FRC in case of accuracy and the least error ratio. Thus, PSO could be applied as a proper tool to maximum accuracy predict the shear strength of FRC.

• Journal of People, Plants, and Environment
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• v.24 no.5
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• pp.485-498
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• 2021

Background and objective: This study was conducted to find out the status of plant utilization in the current textbooks by analyzing the plants by grade and subject in the national textbooks for all elementary school grades in the 2015 revised curriculum in Korea. Methods: The data collected was analyzed using Microsoft Office Excel to obtain the frequency and ratio of collected plant data and SPSS for Windows 26.0 to determine learning content areas by grade and the R program was used to visualize the learning content areas. Results: A total of 232 species of plants were presented 1,047 times in the national textbooks. Based on an analysis of the plants presented by grade, the species that continued to increase in the lower grades tended to decrease in the fifth and sixth grades, the upper grades of elementary school. As for the number and frequency of plant species by subject, Korean Language had the highest number and frequency of plant species. The types of presentation of plants in textbooks were mainly text, followed by illustrations and photos of plants, which were largely used in first grade textbooks. In addition, as for the area of learning contents in which plants are used, in the lower grades, plants were used in the linguistic domain, and in the upper grades, in the botanical and environmental domains of the natural sciences. Herbaceous plants were presented more than woody plants, and according to an analysis of the plants based on the classification of crops, horticultural crops were presented the most, followed by food crops. Out of horticultural crops, flowering plants were found the most diversity with 63 species, but the plants that appeared most frequently were fruit trees that are commonly encountered in real life. Conclusion: As a result of this study, various plant species were included in elementary school textbooks, but most of them were horticultural crops encountered in real life depending on their use. Nevertheless, plant species with high frequency have continued a similar trend of frequency from the previous curriculums. Therefore, in the next curriculum, plant learning materials should be reflected according to social changes and students' preference for plants.

• Journal of People, Plants, and Environment
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• v.23 no.2
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• pp.179-189
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• 2020

In order to increase the indoor air purification effect of plants, plants need to be placed on 5-10% of indoor spaces. To increase the density and utilization of plants in indoor spaces, studies on bio-wall, a vertical green wall system, have been recently conducted. The purpose of this study was to investigate the growth characteristics of 7 indoor plants introduced to the system and their rooting zones at different irrigation cycles. This study was conducted to investigate a proper irrigation cycle for the continuous maintenance of bio-wall systems. The conditions of their growth environment were maintained as follows: light intensity, 20-50 μmol·m^-2·s^-1 PPFD; and temperature, 20 - 25℃. For fertilization, Hyponex diluted with water at the ratio of 1:1,000 was supplied to plants. Irrigation was treated at intervals of 1, 3, 5, and 7 days for 1 hour at a time. As a result, there was no significant difference in the growth of plants between different irrigation cycles. Dieffenbachia 'Marianne' showed a significant decrease in the number of leaves at the irrigation cycle of 7 days. In addition, the chlorophyll content was relatively low at the irrigation cycle of 7 days. In terms of the color of leaves, a decrease in L value and b value and an increase in a value were observed, resulting in changes in brightness and color. Ardisia pusilla 'Variegata' showed a slightly higher photosynthetic activity and stomatal conductance when it was watered every day and once per 5 days, while Epipremnum aureum showed a relatively higher photosynthetic activity and stomatal conductance at the irrigation cycle of 3 days. In the case of root activity, it was found that the longer irrigation cycle, the higher root activity compared to daily irrigation. The development of roots of Peperomia clusiifolia was promoted by watering at long intervals. However, in the case of Aglaonema 'Siam-Aurora', the total number of roots decreased at the interval of 7 days. In conclusion, a proper irrigation cycle for the sustainable maintenance of vertical bio-wall systems seems to be 3 days.

• The Korea Journal of Herbology
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• v.28 no.6
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• pp.79-86
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• 2013

Objectives : The purpose of this study is to investigate neuroprotective effects and molecular mechanisms of luteolin against ${\beta}$-amyloid ($A{\beta}_{25-35}$)-induced oxidative cell death in BV-2 cells. Methods : The protective effects of luteolin against $A{\beta}_{25-35}$-induced cytotoxicity and apoptotic cell death were determined by MTT dye reduction assay and TUNEL staining, respectively. The apoptotic cell death was further analyzed by measuring mitochondrial transmembrane potential and expression of pro- and/or anti-apoptotic proteins. To elucidate the molecular mechanisms underlying the protective effects of luteolin, intracellular accumulation of reactive oxygen species, oxidative damages, and expression of antioxidant enzymes were examined. Results : Luteolin pretreatment effectively attenuated $A{\beta}_{25-35}$-induced apoptotic cell death indices such as DNA fragmentation, dissipation of mitochondrial transmembrane potential, increased Bax/Bcl-2 ratio, and activation of c-Jun N-terminal kinase and caspase-3 in BV-2 cells. Furthermore, $A{\beta}_{25-35}$-induced intracellular formation of reactive oxygen species and subsequent oxidative damages such as lipid peroxidation and depletion of endogenous antioxidant glutathione were suppressed by luteolin treatment. The neuroprotective effects of luteolin might be mediated by up-regulation of cellular antioxidant defense system via up-regulation of ${\gamma}$-glutamylcysteine ligase, a rate-limiting enzyme in the glutathione biosynthesis and superoxide dismutase, an enzyme involved in dismutation of superoxide anion into oxygen and hydrogen peroxide. Conclusions : These findings suggest that luteolin has a potential to protect against $A{\beta}_{25-35}$-induced neuronal cell death and damages thereby exhibiting therapeutic utilization for the prevention and/or treatment of Alzheimer's disease.

• Journal of The Korean Society of Agricultural Engineers
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• v.64 no.4
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• pp.21-30
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• 2022

Renewable energy systems aim to achieve carbon neutrality and replace fossil fuels. Photovoltaic technologies are the most widely used renewable energy. However, they require a large operating area, thereby decreasing available farmland. Accordingly, agrivoltaic systems (AVSs)-innovative smart farm technologies that utilize solar energy for crop growth and electricity production-are attracting attention. Although several empirical studies on these systems have been conducted, comprehensive research on their design is lacking, and no standard model suitable for South Korea has been developed. Therefore, this study created an integral design of AVS reflecting domestic crop cultivation conditions and conducted a structural analysis for safety assessment. The shading ratio, planting distance, and agricultural machinery work of the system were determined. In addition, national construction standards were applied to evaluate their structural safety using a finite element analysis. Through this, the safety of this system was ensured, and structural considerations were put forward. It is expected that the AVS model will allow for a stable utilization of renewable energy and smart farm technologies in rural areas.

• New & Renewable Energy
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• v.18 no.3
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• pp.1-9
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• 2022

This study analyzed the anticipated supply-and-demand of forest biomass energy (through wood pellets) until 2050, in South Korea. Comparing the utilization rates of forest resources of five countries (United Kingdom, Germany, Finland, Japan, and S. Korea), it was found that S. Korea does not nearly utilize its forest resources for energy purposes. The total demand for wood pellets in S. Korea (based on a power generation efficiency of 38%) was predicted to be 3,629 and 4,371 thousand tons in 2034 and 2050, respectively. The anticipated total wood pellet power generation ratio to target power consumption is 1.13% (5,745 GWh), 1.17% (6,336 GWh), and 1.25% (7,631 GWh) in 2020, 2030, and 2050, respectively. Low value-added forest residues left unattended in forests are called "Unused Forest Biomass" in S. Korea. From the analysis, the total annual potential amount of raw material, sustainably collectible amount, and available amount of wood pellet in 2050 were estimated to be 6,877, 4,814, and 3,370 thousand tons, respectively. The rate of contribution to Nationally Determined Contributions was up to 0.64%. Through this study, the authors found that forest biomass energy will contribute to a carbon neutral society in the near future at the national level.

• Journal of Navigation and Port Research
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• v.47 no.2
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• pp.106-119
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• 2023

Due to global decarbonization movement and tightening of maritime emissions restrictions, the shipping industry is going to switch to alternative fuels. Among candidates of alternative fuel, methanol is promising for decreasing SOx and CO2 emissions, resulting in minimum climate change and meeting the goal of green shipping. In this study, a novel combined system of direct methanol solid oxide fuel cells (SOFC), proton exchange membrane fuel cells (PEMFC), gas turbine (GT), and organic Rankine cycle (ORC) targeted for marine vessels was proposed. The SOFC is the main power generator of the system, whereas the GT and PEMFC could recover waste heat from the SOFC to generate useful power and increase waste heat utilizing efficiency of the system. Thermodynamics model of the combined system and each component were established and analyzed. Energy and exergy efficiencies of subsystems and the entire system were estimated with participation of the first and second laws of thermodynamics. The energy and exergy efficiencies of the overall multigeneration system were estimated to be 76.2% and 30.3%, respectively. The combination of GT and PEMFC increased the energy efficiency by 18.91% compared to the SOFC stand-alone system. By changing the methanol distribution ratio from 0.05 to 0.4, energy and exergy efficiencies decreased by 15.49% and 5.41%, respectively. During the starting up and maneuvering period of vessels, a quick response from the power supply system and propulsion plant is necessary. Utilization of PEMFC coupled with SOFC has remarkable meaning and benefits.

• Geomechanics and Engineering
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• v.33 no.1
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• pp.29-40
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• 2023

Xanthan gum and starch compound biopolymer (XS), an environmentally friendly soil-binding material produced from natural resources, has been suggested as a slope protection material to enhance soil strength and erosion resistance. Insufficient wet strength and the consequent durability concerns remain, despite XS biopolymer-soil treatment showing high strength and erosion resistance in the dried state, even with a small dosage of soil mass. These concerns need to be solved to improve the field applicability and post-stability of this treatment. This study explored the utilization of an alkaline-based cation crosslinking method using calcium hydroxide and sodium hydroxide to induce non-thermal gelation, resulting in the enhancement of the wet strength and durability of biopolymer-treated soil. Laboratory experiments were conducted to assess the unconfined compressive strength and cyclic wetting-drying durability performance of the treated soil using a selected recipe based on a preliminary gel formation test. The results demonstrated that the uniformity of the gel structure and gelling time varied depending on the ratio of crosslinkers to biopolymer; consequently, the strength of the soil was affected. Subsequently, site soil treated with the recipe, which showed the best performance in indoor assessment, was implemented on the field slope at the bridge abutment via compaction and pressurized spraying methods to assess feasibility in field implementation. Moreover, the variation in surface soil hardness was monitored periodically for one year. Both slopes implemented by the two construction methods showed sufficient stability against detachment and scouring, with a higher soil hardness index than the natural slope for a year.

• Journal of Animal Science and Technology
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• v.65 no.2
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• pp.387-400
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• 2023

Ruminal protozoa, especially entodiniomorphs, engulf other members of the rumen microbiome in large numbers; and they release oligopeptides and amino acids, which can be fermented to ammonia and volatile fatty acids (VFAs) by amino acid-fermenting bacteria (AAFB). Studies using defaunated (protozoa-free) sheep have demonstrated that ruminal protozoa considerably increase intraruminal nitrogen recycling but decrease nitrogen utilization efficiency in ruminants. However, direct interactions between ruminal protozoa and AAFB have not been demonstrated because of their inability to establish axenic cultures of any ruminal protozoan. Thus, this study was performed to evaluate the interaction between Entodinium caudatum, which is the most predominant rumen ciliate species, and an AAFB consortium in terms of feed degradation and ammonia production along with the microbial population shift of select bacterial species (Prevotella ruminicola, Clostridium aminophilum, and Peptostreptococcus anaerobius). From an Ent. caudatum culture that had been maintained by daily feeding and transfers every 3 or 4 days, the bacteria and methanogens loosely associated with Ent. caudatum cells were removed by filtration and washing. An AAFB consortium was established by repeated transfers and enrichment with casamino acids as the sole substrate. The cultures of Ent. caudatum alone (Ec) and AAFB alone (AAFB) and the co-culture of Ent. caudatum and AAFB (Ec + AAFB) were set up in three replicates and incubated at 39℃ for 72 h. The digestibility of dry matter (DM) and fiber (NDF), VFA profiles, ammonia concentrations, pH, and microscopic counts of Ent. caudatum were compared among the three cultures. The co-culture of AAFB and Ent. caudatum enhanced DM degradation, VFA production, and Ent. caudatum cell counts; conversely, it decreased acetate: propionate ratio although the total bacterial abundance was similar between Ec and the Ec + AAFB co-culture after 24 h incubation. The ammonia production and relative abundance of C. aminophilum and P. anaerobius did not differ between AAFB alone and the Ec + AAFB co-culture. Our results indicate that Ent. caudatum and AAFB could have a mutualistic interaction that benefited each other, but their interactions were complex and might not increase ammoniagenesis. Further research should examine how such interactions affect the population dynamics of AAFB.

• Journal of Hydrogen and New Energy
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• v.33 no.6
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• pp.660-673
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• 2022

In achieving carbon neutrality and the hydrogen economy, the estimation of H₂ cost is critical in terms of CCU technologies. This study analyzes LCOH of hydrogen produced by the carbon utilization unit with methane reforming and CO₂ from thermal power plant. LCOH for H₂ made with CO is estimated in three ways of Joint Cost Allocations with financial performance risk assessment. Regarding cost analysis, the zero value of LCOH is $6,003/ton. We found that the CCU technology has economic feasibility in terms of profitability. The sensitivity analysis result shows that the input ratio is more influential to the LCOH than other variables. Risk analysis presents the baseline price of zero value of LCOH - $8,408/ton, which is higher than the cost analysis - $6,003/ton. Mainly, the price variability of natural gas primarily affects the LCOH. The study has significant value in analyzing the financial performance risks as well as the cost of H₂ produced by a Plasma-based CCU system.