• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.272-278
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• 2018

Traffic volume has been greatly increasing due to urban development and the improvement of living standards, and many complaints are being raised due to the increasing road noise. As a countermeasure against these problems, highly soundproof walls are installed on the sides of roads. However, the ability to bear wind loads is a major design requirement for soundproof walls, which contributes to the exponential increases in construction costs and restricts the height of the walls. The aim of this study is to improve the performance of soundproof walls and to dramatically reduce wind loads while maintaining excellent price competitiveness. Based on Helmholz's resonator theory, a new concept is proposed for a ventilation-type soundproofing plate that can pass through a fluid like air and reduce noise. A full-scale metal soundproofing plate was produced to satisfy the quality standards of highways by conducting a sound-pressure transmission-loss test, wind tunnel test, and material quality test. To verify the reliability, the wall was manufactured and installed, and the sound insulation effect was examined by measuring the noise over time. In the future, ventilated soundproof walls on roads could create a pleasant living environment due to the high noise-insulation effect.

• Tunnel and Underground Space
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• v.31 no.5
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• pp.333-359
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• 2021

Gases such as hydrogen and radon can be generated around the canister in high-level radioactive waste disposal systems due to several reasons including the corrosion of metal materials. When the gas generation rate exceeds the gas diffusion rate in the low-permeability bentonite buffer, the gas phase will form and accumulate in the engineered barrier system. If the gas pressure exceeds the gas entry pressure, gas can migrate into the bentonite buffer, resulting in pathway dilation flow and advective flow. Because a sudden occurrence of dilation flow can cause radionuclide leakage out of the engineered barrier of the radioactive waste disposal system, it is necessary to understand the gas migration behavior in the bentonite buffer to quantitatively evaluate the long-term safety of the engineered barrier. Experimental research investigating the characteristics of gas migration in saturated bentonite and research developing numerical models capable of simulating such behaviors are being actively conducted worldwide. In this technical note, previous gas injection experiments and the numerical models proposed to verify such behaviors are introduced, and the future challenges necessary for the investigation of gas migration are summarized.

• Korean Journal of Poultry Science
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• v.49 no.4
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• pp.221-228
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• 2022

Major egg white proteins and their hydrolysates serve as functional food ingredients that have certain metal-chelating properties. Employing egg white proteins and their hydrolysates to scavenge dietary oxalates is anticipated to have beneficial effect in the prevention of kidney stones. The objective of this study was to determine the biogenic oxalate-chelating activity of ovalbumin, ovomucin, and ovotransferrin and their hydrolysates. To prepare oxalate extracts, 30 mL of 0.25 N HCl was added to separately to 0.5 g of dried spinach and starfruit powders followed by boiling for 15 min, and after cooling, the addition of a further 20 mL of 0.25 N HCl. Having prepared these extracts, ovalbumin, ovomucin, and ovotransferrin and their hydrolysates were separately mixed with oxalate extracts and incubated at 3℃ for 24 h. Following centrifugation, supernatants were analyzed by HPLC using a reverse-phase C18 column coupled with a diode array detector. We found that all assessed proteins and their hydrolysates showed biogenic oxalate-chelating activity against the oxalates of spinach. In contrast, however, only ovalbumin, ovalbumin-hydrolysate, and ovomucin showed chelating activity (57.10%±8.84%, 85.44%±5.30%, 73.20%±4.13%, respectively) against the oxalates of starfruit (P<0.05). Overall, hydrolyzed ovalbumin was identified as the most effective chelator of the oxalates both spinach and starfruit. In this study, we thus established that the assessed egg white proteins and their hydrolysates have oxalate-chelating activity in vitro, thereby indicating that these compounds have potential utility as nutraceuticals for the chelation of dietary oxalate. However, further research will be necessary to verify their oxalate-chelating activities against different fruits and vegetables and under specific in vivo conditions and against purified oxalate.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.4
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• pp.504-511
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• 1995

This study was conducted to investigate the superoxide dismutase (SOD) characteristics and antioxidant activity by nonenzymatic(Fe$^{2+}$/Ascorbate) and Fe$^{3+}$-ADP/NADPH method in perilla(Perilla frutescens var. japonica Hara.) and jaso(Perilla frutescens Briton var. acuta Kudo.) leaves. The characteristics were evaluated by the nitro blue tetrazolium reduction method. Perilla leaves contained three or four major SODs depending on the varieties. The inhibitor test indicated that the Perilla leaves contained two Cu /ZnSODs and one or two FeSODs, but Jaso leaves have only Cu/ZnSOD. However, no varietal differences were detected in the Cu /ZnSOD isozyme patterns. FeSODs, however, showed different varietal isozyme patterns through the different combinations of the two FeSOD isozymes. Among MeOH extractes, "mil yang 2" showed very strong antioxidant activity. Relatively large differences in the levels of SOD and antioxidant activity detected in the Perilla varietites. There was significantly different in the comparison between perilla leaves and red jaso leaves.s.etween perilla leaves and red jaso leaves.

• Clean Technology
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• v.29 no.3
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• pp.163-171
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• 2023

Hydrogen has been gaining a lot of attention as a possible clean energy source that can aid in reaching carbon neutrality. Currently, hydrogen production has relied on the steam reforming of fossil fuels. However, due to the carbon dioxide emissions caused by this process, hydrogen production based on the steam reforming of bio-oil derived from biomass has been proposed as an alternative approach. In order to use this alternative approach efficiently, one of the key issues that must be overcome is that the complexity of bio-oil, which has a large molecular weight and diverse functional groups of hydrocarbons, promotes the catalytic deactivation of nickel-based catalysts. In this review, research efforts to improve nickel-based catalysts for the steam reforming of bio-oil have been discussed in terms of the active phase, support, and promoters. The active phases are involved in activating C-C and C-H bonds of high-molecular-weight hydrocarbons, and noble and transition metals can be utilized. In terms of the support and promoters, the catalytic deactivation of Ni-based catalysts can be inhibited by utilizing reactive lattice oxygen for support or by suppressing the acidity. The development of active and stable Ni-based reforming catalysts plays a critical role in clean hydrogen production based on bio-oils.

• Resources Recycling
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• v.31 no.6
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• pp.81-91
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• 2022

The use of lithium-ion batteries increases significantly with the rapid spread of electronic devices and electric vehicle and thereby an increase in the amount of waste batteries is expected in the near future. Therefore, studies are continuously being conducted to recover various resources of cathode active material (Ni, Co, Mn, Li) from waste battery. In order to recover the cathode active material, black mass is generally recovered from waste battery. The general process of recovering black mass is a waste battery collection - discharge - dismantling - crushing - classification process. This study focus on the crushing/classification process among the processes. Specifically, the particle size distribution of various samples at each crushing/classification step were evaluated, and the particle shape of each particle fraction was analyzed with a microscope and SEM (Scanning Electron Microscopy)-EDS(Energy Dispersive Spectrometer). As a result, among the black mass particle, fine particle less than 74 ㎛ was the mixture of cathode and anode active material which are properly liberated from the current metals. However, coarse particle larger than 100 ㎛ was present in a form in which the current metal and active material were combined. In addition, this study developed a PBM(Population Balance Model) system that can simulate two-species mixture sample with two different crushing properties. Using developed model, the breakage parameters of two species was derived and predictive performance of breakage distribution was verified.

• Applied Chemistry for Engineering
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• v.34 no.3
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• pp.213-220
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• 2023

Mixed-matrix membranes (MMMs), which are composed of a polymer matrix filled with high-performance fillers as a dispersed phase, have been intensively studied for gas separations for the past 30 years. It has been demonstrated that MMMs exhibit superior gas separation performance compared to polymer membranes and are more scalable than polycrystalline membranes. Despite their potential, the commercialization of MMMs has yet to be reported due to several challenging issues. One of the major challenges of MMMs is the non-ideal interface between the continuous polymer phase and dispersed phase, which can result in defect formation (i.e., interfacial voids, etc.). With respect, many MMM studies have focused on addressing the issues through scientific approaches. The engineering approaches for facile and effective large-scale fabrication of MMMs, however, have been relatively underestimated. In this review paper, a novel strategy for fabricating MMMs in a facile and scalable manner using in situ metal-organic framework (MOF) formation is introduced. This new MMM fabrication methodology can effectively address the issues facing current MMMs, likely facilitating the commercialization of MMMs.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.3
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• pp.185-191
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• 2023

Research to analyze the future prediction of value is being conducted in various. However, it was found through the research results of each field that such future value analysis has too many variables according to each field, so the accuracy of the prediction result is low, and it is difficult to find objective key influencing factors that affect the result. In particular, since objective standards for the importance of various influencing factors have not been established, the key influencing factors have been judged and applied based on the researcher's subjectivity. Accordingly, there is a need for a reasonable process model for extracting key influencing factors that affect the prediction of volatility goods value that can be objectively applied in various fields. In this study, process modeling for extracting key influencing factors was conducted in seven steps, and the method for extracting key influencing factors was explained in detail in each step. In addition, as a result of simulation by applying Ni metal among the major variable goods in the field of raw materials using the proposed modeling, the predicted value by the existing method was 0.872% and the predicted value by applying the modeling of this study was 0.864%. conformance was confirmed.

• Journal of Environmental Impact Assessment
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• v.32 no.3
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• pp.157-165
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• 2023

In Korea, a major contaminant of farmland soils in the vicinity of abandoned mines is arsenic, for which the general soil reclamation method is contaminated soil stabilization and cover the stabilized soil with clean soil at a thickness of 40 cm. In a previous pot experiment study we confirmed the feasibility of a lower thickness (20 cm) of covering soil for such reclamation in abandoned coal mines, where arsenic contamination levels are generally lower than in metal mines. In this subsequent study a field experiment including rice plant cultivation in field test plots was conducted. For over 4 months, the transfer of arsenic from the contaminated soil to the unpolished rice grains was reduced by 44% when a clean soil covering with a thickness of 20 cm was applied. The maximum decrease (56%) was shown when the stabilization process was performed before the covering. These results reveal a lower thickness of clean soil covering has a high feasibility and it can increase cost-efficiency in the reclamation of an abandoned coal mine.

• Journal of Life Science
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• v.34 no.1
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• pp.68-77
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• 2024

Airborne particulate matter (PM) is an environmentally hazardous pollutant that originates from various sources. PM is comprised of solid particles and liquid droplets of diverse composition and size. Hazardous chemical compositions of PM include elemental and organic carbon, organic compounds, biological compounds and metals. Upon acute and chronic PM exposure, toxic contaminants enter and accumulate within physiological systems and prompt cell structure changes accompanied with intracellular endoplasmic reticulum stress, mitochondrial dysfunction, oxidative stress, inflammation, lipid accumulation, and cell cycle arrest. Ultimately, these cellular response leads to the development of key characteristics of aging. In addition, PM internalization enhances autophagy reflux and lysosomal dysfunction, which is involved in cell aging. Previous studies have emphasized a positive association between PM and increased mortality or decreased lifespan, although these are evidenced mostly by observational studies. Direct evidence of the link between PM and aging is still limited. This review evaluates the evidence from not only observational studies but also in vitro and in vivo evidence of PM on aging progression and age-related diseases development. This evidence is based on age-associated cellular changes including endoplasmic reticulum stress, mitochondrial dysfunction, oxidative stress, inflammation, adipose accumulation, autophagy, which strengthen the association between PM exposure and aging. Understanding the underlying cellular responses under PM may allow for the development of new therapeutic targets for PM-induced aging.