• Food Engineering Progress
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• v.22 no.4
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• pp.321-327
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• 2018

The main purposes of this study were to identify the factors affecting the supercooling property and to improve the possibility of supercooling storage of fruits and vegetables. Freezing point and nucleation temperature, moisture content, hardness, sugar content, and pH of nineteen fruits and vegetables were measured and Pearson correlation analysis was performed. Freezing point showed a statistically significant correlation with moisture content and sugar content (p<0.01), while ice nucleation temperature showed a correlation (p<0.05) only for sugar content. In particular, the water content and sugar content did not show any correlation with the freezing supercooling difference (FSD). From the correlation analysis between FSD, aerobic bacteria, lactic acid bacteria, yeast, and mold, FSD showed a correlation (p<0.01) with aerobic bacteria. The experiments of the saline solutions inoculated with aerobic bacteria at different concentrations showed FSDs of about 2 for saline inoculated with 9.4 log CFU/mL and about 6 for saline inoculated lower than 5 log CFU/mL. Therefore, the aerobic bacteria concentration was determined to be a key factor affecting the supercooling storage of fruits and vegetables.

• Clean Technology
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• v.26 no.4
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• pp.263-269
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• 2020

Zeolite was synthesized hydrothermally using the water-treatment sludge, and the effects of various synthesis parameters like reaction temperature, reaction time, and Na2O/SiO2 molar ratio on the crystallization of zeolite were investigated. Crystal structure, physical property, and thermal stability of zeolite crystals were characterized by X-ray powder diffraction, FTIR spectroscopy, BET nitrogen adsorption, and TGA measurements. The removal efficiencies of nitrogen in ammonia, heavy metal ions, and TOC were calculated to evaluate zeolite's adsorption capacity. The primary chemical composition of water-treatment sludge was 28.79% Al2O3 and 27.06% SiO2. The zeolites were synthesized by merely employing the water-treatment sludge as silica and alumina sources without additional chemicals. Zeolite crystals synthesized through the water-treatment sludge were confirmed as an A-type zeolite structure. Zeolite A had the highest crystallinity obtained from a gel with the molar composition 2.1Na2O-Al2O3-1.6SiO2-65H2O after 5 h at a temperature of 90 ℃. The specific surface area of zeolite obtained was 55 ㎡ g-1, which was higher than commercial zeolite A. The removal efficiency of nitrogen in ammonia was 68% after 3 h of reaction time, while the removal efficiencies of Pb2+ and Cd2+ ions were 99.1% and 99.3%, respectively. These results indicate active ion exchange between Pb2+ or Cd2+ ion and Na+ ion in the zeolite framework. The adsorption experiments on the different zeolite addition conditions were performed for 3 h with 300 ppm humic acid. Based on the results, TOC's highest efficiency was 83% when 5 g of zeolite was added.

• Applied Chemistry for Engineering
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• v.34 no.1
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• pp.15-22
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• 2023

Recent studies have actively investigated ways to improve the economic feasibility and efficiency of the Fischer-Tropsch process by increasing the yields of the monocyclic aromatic compounds (BTEX). In this study, ethylene was selected as a model of F-T-derived hydrocarbons, and the ethylene-to-aromatics (ETA) reaction was investigated according to changes in acid characteristics, mesopores, and crystallinity of HZSM-5 (HZ5). Fluorinated HZ5 was prepared by calcination followed by impregnation of an aqueous NH₄F solution having different molar concentrations in HZ5, and the structural and chemical properties of F/HZ5 were investigated through Brunauer-Emmett-Teller (BET), solid-state nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS), NH₃-temperature-programmed desorption (TPD), and pyridine-IR spectroscopy. The ETA reactions were performed at 673 K under 0.1 MPa, and fluorinating HZ5 by an aqueous NH₄F solution of 0.17 M improved ethylene conversion, BTEX selectivity, and catalytic stability due to acidity, mesopore fraction, and crystallinity.

• Korean Chemical Engineering Research
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• v.60 no.3
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• pp.446-451
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• 2022

In this study, to improve capacity and cycle stability, the pitch coated nano silicon sheets/CNT composites were prepared through electrostatic bonding of nano silicon sheets and CNT. Silica sheets were synthesized by hydrolyzing TEOS on the crystal planes of NaCl, and then nano silicon sheets were prepared by using magnesiothermic reduction method. To fabricate the nano silicon sheets/CNT composites, the negatively charged CNT after the acid treatment was used to assemble the positively charged nano silicon sheets modified with APTES. THF as a solvent was used in the coating process of PFO pitch. The physical properties of the prepared anode composites were analysed by FE-SEM, XRD and EDS. The electrochemical performances of the synthesized anode composites were performed by current charge/discharge, rate performances, differential capacity and EIS tests in the electrolyte LiPF₆ dissolve solvent (EC:DMC:EMC = 1:1:1 vol%). It was found that the anode material with high capacity and stability could be synthesized when high composition of silicon and conductivity of CNT were used. The pitch coated nano silicon sheets/CNT anode composites showed initial discharge capacity of 2344.9 mAh/g and the capacity retention ratio of 81% after 50 cycles. The electrochemical property of pitch coated anode material was more improved than that of the nano silicon sheets/CNT composites.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.29 no.2
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• pp.79-86
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• 2023

In this study, poly(lactic acid) (PLA) and Poly(butylene-adipate-co-terephthalate) (PBAT) composite films containing calcined oyster shell powder (OSP) were evaluated for the applicability of antimicrobial packaging. PLA/PBAT-OSP composite films were prepared using twin-screw extruder. The OSP composite was incorporated into PLA/PBAT blend with different ratios (0, 1, 3, 5 and 10%) and the effect of OSP in the PLA/PBAT matrix was evaluated. The PLA/PBAT-OSP composite films were evaluated for properties using FT-IR, SEM, TGA, DSC, UTM, UV-vis, and Contact angle, as well as antimicrobial property was examined according to ISO 22196 - Antimicrobial Plastic Test. As OSP was added, it showed high antimicrobial activities for both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. On the other hand, it was found that mechanical properties decreased as OSP was added. For the application of PLA/PBAT-OSP composite films as an antimicrobial packaging material, it is necessary to improve the dispersibility of OSP in the PLA/PBAT composite films and their physical properties at the same time.

• Animal Bioscience
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• v.36 no.6
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• pp.943-952
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• 2023

Objective: For decades, LYD ([Landrace×Yorkshire] ♀×Duroc ♂) pigs are the most commonly-used commercial breed for meat production in Korea. Recently, due to the increasing demand for premium pork, the National Institute of Animal Science (Korea) has synthesized a novel pig breed named Woori Heukdon (WHD). This study aimed at comparing the carcass traits, meat yield and quality characteristics between the LYD and WHD pigs under identical rearing condition. Methods: The WHD and LYD pigs (n = 15 each) were reared under identical conditions and fed the same commercial diet until reaching recommended market weight (100 to 120 kg). After slaughter, the carcasses were evaluated for traits and meat yield, and the meat quality was assessed on shoulder butt and belly cuts. Results: Although no significant differences (p>0.05) occurred in slaughter weight between two pig types, WHD had a lower meat yield (by about 6 kg corresponding to approximately 7%) compared to the LYD pigs (p<0.05). The WHD had a higher fat content (by 4.26% and 13.52% in the shoulder butt and belly, respectively) compared to those of LYD pigs (p<0.05). The WHD meat showed a lower cooking loss and higher a* (redness) value (p<0.05). The WHD belly had a significantly (p<0.05) higher oleic acid content and concentrations of nonanal, octanal and decanal associated with fatty odor while, the LYD meat had a higher number of pyrazines associated with roasty odor. Regarding sensory quality, higher flavor, juiciness, and acceptability higher scores were given for the WHD meat than for the LYD meat (p<0.05). Conclusion: Under identical rearing conditions the WHD exhibited a better meat quality and sensory properties. However, the use of this diet resulted in a high fat level that may be associated with high trimming loss for the WHD.

• Economic and Environmental Geology
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• v.56 no.6
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• pp.675-695
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• 2023

The tracksite of dinosaurs and pterosaurs in Sanbuk-dong of Gunsan is the largest early Cretaceous dinosaur footprint fossil site in Korea, and all the footprints are important evidence indicating that large ornithopod and theropod dinosaurs inhabited the Korean peninsula during the early Cretaceous. The Sanbuk-dong site was covered with waterproof sheet in an outdoor environment until the installation of a protective enclosure in 2021. As a result, various factors such as shear force, load reduction, temperature and humidity fluctuations, acid rain, salinity and microorganisms have complexly interacted in the substrate of fossils, exacerbating the damage to footprints. For 159 footprints in 12 trackways among the footprints found in the site, the damage types were classified in detail and the level of each damage was assessed. The damages were classified into 6 types through the classification of deterioration degree of individual footprints. As a result of ultrasonic physical property evaluation on the surface of the fossil site, most of these footprints are in the completely weathered (CW) stage. Furthermore, various weathering patterns were observed in the study area, and surface contaminants were analyzed along the stratigraphy. Although the patterns of freshness and contaminants varied at different points within the fossil site, the chemical compositions were similar. Based on the results, an efficient conservation management system for dinosaur footprint fossils was established, and a conservation treatment type for each footprint was proposed.

• Journal of the Korea Organic Resources Recycling Association
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• v.32 no.3
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• pp.57-66
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• 2024

In this study, silicon sludge from a semiconductor packaging process is recycled to fabricate silica coated silicon-sludge and applied as a filler for an epoxy molding compound(EMC). Silicon-sludge powder(S-sludge) is treated with acid to remove metallic impurities and then coated using the sol-gel method to synthesize silica coated silicon-sludge powder(SS-sludge). The as-synthesized SS-sludge is subsequently mixed with epoxy resin, a curing agent, and carbon black to create an EMC(SS-sludge EMC). The heat dissipation properties of the EMC were examined using an IR camera. IR camera analysis confirmed that the SS-sludge EMC exhibited the highest surface temperature of 58.5℃ compared to SiO₂-based EMC. This enhancement in heat dissipation using SS-sludge EMC is attributed to the excellent thermal conductivity(150W/mK) of the silicon substrate and the presence of the silica layer on the SS-sludge surface which effectively enhances the thermal property of the EMC. Therefore, this study successfully demonstrates the recycling of silicon sludge from a semiconductor packaging process by synthesizing silica coated silicon-sludge and suggests a novel application of this material in semiconductor packaging.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.3
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• pp.267-274
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• 2017

This study discusses the applicability of environmental friendly EVA based butyl rubber self-adhesive waterproof sheet designed to prevent corrosion of large scale pipes used in the water treatment facilities during th water treatment process. The experiments conducted tested the waterproofing sheet's adhesion strength on the steel surface of the pipes and checked for whether the material has the proper response properties against the various environmental conditions. In addition, it the sheet adhered to the steel pipe was to see if the adhesion hold against the water pressure due to the ingress of inflow water. Finally, the waterproofing sheet's adhesion strength was tested on a rusted steel surface to confirm whether the material has the necessary properties to secure stable adhesion strength and prevent corrosion of steel pipes at the same time during the process of installation or maintenance. As a result, the self-adhesive waterproof sheets showed that all attachments in the untreated, long term pressuring, immersion in chemical substance (hydrochloric acid, hypochlorous acid, sodium hydroxide), low temperature ($-20^{\circ}C$) conditions showed a adhesion performance of higher than 1.5N/mm, which is the performance standard of KS F 4934. Also, in the testing to check for the adhesion property against inverse water pressure, it was observed that the adhesion failure did not occur even up to $3.0N/mm^2$ pressure. Also, in the process of assessing the adhesion performance on rusted steel surface, specimens after 12 hours of corrosion treatment was shown to have 2.1N/mm, and specimens after 168 hours of corrosion treatment was shown to have 2.0N/mm adhesion strength performance.

• Korean Journal of Food Science and Technology
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• v.43 no.5
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• pp.588-596
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• 2011

Wild grape extract (WGE) was added into hwajeon at different concentrations (0, 5, 15, 30, 50% of water). The resulting hwajeon were analyzed for their physicochemical and sensory properties. With increasing concentrations of WGE, the pH of dough and hwajeon decreased, and their degrees brix and color intensity increased, presumably due to the presence of tartaric acid, sugar, and anthocyanin in the WGE. The WGE-enriched hwajeon showed higher hardness, gumminess, and chewiness than control hwajeon, which might have been because the sugar and tartaric acid in the WGE partially inhibited starch gelatinization during heat processing. Nevertheless, all the sensory properties and preference were higher in WGE-enriched hwajeon than controls, which could be partially attributed to the fact of that the WGE-enriched hwajeon retained relatively higher moisture. It is suggested that WGE-enriched hwajeon with high preference could be prepared without loss of hwajeon quality.