• Particle and aerosol research
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• v.19 no.2
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• pp.31-42
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• 2023

The charge and magnetic characteristics of LM (Low-metallic) and NAO (Non-asbestos-organic) brake wear particles were analyzed. The ratio of charged particles from total particles is about 86% of the LM pad and about 92% of the NAO pad. Number of charge per particle from the NAO pad is also higher than that of the LM pad. The ratio of magnetic particles from total particles increases with the particle size. The ratio of magnetic particles from the LM pad is about 15% for the particles with the size of 1 ㎛, and about 74% for ones with 5 ㎛. The ratio from the NAO pad is about 5% for the particles with the size from 0.5 ㎛ to 2 ㎛, and about 80% for the particles with 5 ㎛. Through the analysis of the components of the two pads with SEM-EDS (Scanning Electron Microscopy - Energy Dispersive X-ray Spectroscopy), it was found that the LM pad was occupied with more iron fraction than the NAO pad and that PM_2.5-10 was occupied with more iron fraction than PM_2.5. The particles smaller than 10 ㎛ (i.e. PM₁₀) from the LM pad contained about 83% of charged particles, about 43% of magnetic particles, and about 93% of charged or magnetic particles. PM₁₀ from the NAO pad contained about 88% of charged particles, about 15% of magnetic particles, and about 89% of charged or magnetic particles.

• Restorative Dentistry and Endodontics
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• v.47 no.4
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• pp.36.1-36.17
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• 2022

Objectives: This study aimed to evaluate the effect of aging on the marginal quality of glass hybrid (GH) material used to elevate dentin gingival margins, and to analyze the consistency of the results obtained by 3 in vitro methods. Materials and Methods: Ten teeth received compound class II cavities with subgingival margins. The dentin gingival margins were elevated with GH, followed by resin composite. The GH/gingival dentin interfaces were examined through digital microscopy, scanning electron microscopy (SEM) using resin replicas, and according to the World Dental Federation (FDI) criteria. After initial evaluations, all teeth were subjected to 10,000 thermal cycles, followed by repeating the same marginal evaluations and energy dispersive spectroscopy (EDS) analysis for the interfacial zone of 2 specimens. Marginal quality was expressed as the percentage of continuous margin at ×200 for microscopic techniques and as the frequency of each score for FDI ranking. Data were analyzed using the paired sample t-test, Wilcoxon signed-rank test, and Pearson and Spearmen correlation coefficients. Results: None of the testing techniques proved the significance of the aging factor. Moderate and strong significant correlations were found between the testing techniques. The EDS results suggested the presence of an ion-exchange layer along the GH/gingival dentin interface of aged specimens. Conclusions: The marginal quality of the GH/dentin gingival interface defied aging by thermocycling. The replica SEM and FDI ranking results had stronger correlations with each other than either showed with the digital microscopy results.

• Journal of Korea Foundry Society
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• v.43 no.6
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• pp.286-293
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• 2023

In this study, we investigated the microstructural evolution of Al-Mg-Zn aluminum alloy billet during homogenization treatment using OM, SEM, EDS and DSC. There were numerous phases found, such as; AlMgZn, AlMgFe, and AlMgZnSi phases, in the grain of the cast billet. After 6 hours homogenization treatment, Zn was mostly dissolved, whereas, Mg and Si were only partly dissolved. Accordingly, only AlMgFe and AlMgSi remained. After 18 hours, all of the leftover Mg and Si were dissolved, leaving only AlMgFe, which was also found after 24 hours. The results of the alloy design program, JMatPro showed that Mg dissloved more rapidly than Zn. According to the homogenization kinetic equation, Mg and Zn are completely dissolved within 1.9 and 3.5 hours, respectively.

• Journal of the Korean Recycled Construction Resources Institute
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• v.12 no.1
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• pp.33-39
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• 2024

In this study, the basic properties of cement paste with varying replacement ratio of micro-silica and fumed silica were analyzed to determine the suitability of nanomaterials for use as concrete admixtures. Referring to the ultra-high strength mix, the fluidity of cement paste was evaluated according to the nanomaterial replacement rate and the compressive strength characteristics were compared and analyzed. The related properties of the reactive nanomaterials to the cement hydrate were analyzed using SEM and EDS to observe the microstructure and identify the components of the hydration product. The reactive nanomaterials used in this study had tap densities between 0.061 and 0.264 g/cm³, which were lower than SF. Micro silica exhibited excellent compressive strength properties with increasing replacement ratio, but fumed silica, unlike micro white, obtained excellent compressive strength at replacement ratio of 0.01~0.1 %. The same trend was observed in the hydration characterization.

• Economic and Environmental Geology
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• v.50 no.4
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• pp.257-266
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• 2017

Batch experiments were performed to develop the method for the pH reduction of recycled aggregate by using $scCO_2$ (supercritical $CO_2$), maintaining the pH of extraction water below 9.8. Three different aggregate types from a domestic company were used for the $scCO_2$-water-recycled aggregate reaction to investigate the low pH maintenance of aggregate during the reaction. Thirty five gram of recycled aggregate sample was mixed with 70 mL of distilled water in a Teflon beaker, which was fixed in a high pressurized stainless steel cell (150 mL of capacity). The inside of the cell was pressurized to 100 bar and each cell was located in an oven at $50^{\circ}C$ for 50 days and the pH and ion concentrations of water in the cell were measured at a different reaction time interval. The XRD and SEM-EDS analyses for the aggregate before and after the reaction were performed to identify the mineralogical change during the reaction. The extraction experiment for the aggregate was also conducted to investigate the pH change of extracted water by the $scCO_2$ treatment. The pH of the recycled aggregate without the $scCO_2$ treatment maintained over 12, but its pH dramatically decreased to below 7 after 1 hour reaction and maintained below 8 for 50 day reaction. Concentration of $Ca^{2+}$, $Si^{4+}$, $Mg^{2+}$ and $Na^+$ increased in water due to the $scCO_2$-water-recycled aggregate reaction and lots of secondary precipitates such as calcite, amorphous silicate, and hydroxide minerals were found by XRD and SEM-EDS analyses. The pH of extracted water from the recycled aggregates without the $scCO_2$ treatment maintained over 12, but the pH of extracted water with the $scCO_2$ treatment kept below 9 of pH for both of 50 day and 1 day treatment, suggesting that the recycled aggregate with the $scCO_2$ treatment can be reused in real construction sites.

• Journal of Conservation Science
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• v.16 s.16
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• pp.64-76
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• 2004

This study was performed by chemical analysis and metallographic observation. Chemical properties were analized by ICP, XRD and SEM-EDS and slag structures were observed by microscope and SEM. Total Fe amounts in A, C area of slag can be observed $39\~45\%$ by chemical analysis results. It was average of acient times. CaO was $3\~8\%$. It's not plentiful but we think that was artificial. Ti was found in A area a little, and Ti, V were found in C area so much. The compounds, as if Fayalite, Wustite, Magnetite, Ilmenite, Pseudo-brookite, Ulvospinel, Forsterite, Fephroite, Olivine were observed in the result XRD. These structures were also observed in microscope and SEM image. Therefore, The furnance of A area usually used an iron mine, An Iron furnance of C area considered it which refined using a raw iron mine and a raw iron sand.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.6
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• pp.654-661
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• 2007

The goal of this research was to identify the impact of silicate polymerization on the formation of insoluble aluminiumsilicate salts which could be a cause of irreversible fouling in the membrane process by lab-scale test. For this, the amount and characteristics of precipitates that were formed in six samples with different Al and Si concentration were analyzed. And the particles was also observed by SEM-EDS(Scanning Electron Microscope - Electron Dispersion Spectrophotometer) to compare morphology and ratio of Al and Si in each precipitates. Finally the reactive and nonreactive silicate contents in the solution and precipitates were analyzed to calculate silicate form content in each fraction. The amount of precipitates was in proportion to the total concentration of both element in solution. And the amount of insoluble particle that was not dissolved in the acid solution was recorded the highest in the sample 2 of which Si concentration was lower than the saturation concentration, 50 mg/L. The content of reactive silicate in precipitates was also recorded the highest value in sample 2 of which almost silicate form was reactive. When the silicate concentration is same, that value was recorded the highest in the sample with highest Al concentration. The SEM morphology of the precipitates was similar to that of Aluminiumhydroxide and the insoluble precipitates was not dissolved in acidic solution with pH 2.7 was able to observed only in sample 2. The ratio of Al and Si in the precipitates was ranged $0.48\sim3.14$, thai of sample 2 was recorded the highest value, 3.14. It is concluded that the insoluble aluminiumsilicate could be easily formed in the solution of which silicate exist as a reactive form and coexisting Al is sufficient.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.200.1-200.1
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• 2016

Tungsten coatings on the graphite (CX-2320) were successfully deposited using the vacuum plasma spraying (VPS) method. An optimum coating procedure was developed and coating thicknesses of $409{\mu}m$ (without an interlayer) and $378{\mu}m$ (with an interlayer) were obtained with no cracks and no signs of delamination. The mechanical characteristics and microstructure of the tungsten coating layers were investigated using a Vickers hardness tester, FE-SEM, EDS, and XRD. The effect of a titanium interlayer on the properties of the tungsten coating was investigated. It was shown that the titanium interlayer prevented the diffusion of carbon to the tungsten layer, thereby suppressing the formation of tungsten carbide. Vickers hardness data yielded values that were 62.5 ~ 80.46% of those for bulk tungsten, indicating that tungsten coatings on graphite can be utilized as a plasma-facing material. High heat flux tests were performed by using thermal plasma with a maximum flux of $10MW/^2$. Vickers hardness after the heat flux test is performed to see a change in the mechanical properties. The formationof a tungsten carbide and the effect of the titanium interlayer for the diffusion barrier are investigated by using energy dispersion spectroscopy (EDS).

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.6
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• pp.241-248
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• 2003

$Bi_{1.84}Pb_{0.34}Sr_{1.91}Ca_{2.03}Cu_{3.06}O_{10+\delta}$ high $T_{c}$ superconductors containing Ag as an additive were fabricated by a solid-state reaction method. The superconducting properties, such as the structural characteristics, the critical temperatures, the grain size and the image of mapping on the surface were investigated. Samples with Ag and Au of 50 wt% each were sintered at various temperature(820~$850^{\circ}C$). The structural characteristics, the microstructure of surface and the critical temperature with respect to the each samples were analyzed by XRD and SEM, EDS and four-prove methode respectively. The critical temperature showed the result which the Ag additive samples are higher than Au additive samples. The microstructure of the surface showed the tendency which the Ag additive samples become more minuteness than Au additive samples.

• Textile Coloration and Finishing
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• v.28 no.4
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• pp.271-279
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• 2016

This study deals with antibacterial properties of nylon fiber treated with glycidyltrimethylammonium chloride(GTAC) and silver nanoparticles(AgNPs). Nylon fibers were soaked into GTAC(2-30%, v:v) solution for 20 min. After sample was pre-drying at $80^{\circ}C$ for 10min and cured at $180^{\circ}C$ for 5min. The AgNPs coating was accomplished by soaking in silver colloid solution at $45^{\circ}C$ for 90min. The coated nylon fibers were characterized by scanning electron microscopy-energy dispersive spectroscopy(SEM-EDS). EDS analysis indicated that AgNPs and GTAC was attached on nylon fibers. The treated nylon fibers showed antimicrobial properties against Escherichia coli(ATCC 43895), Pseudomonas aeruginosa(ATCC 13388) and Staphylococcus aureus(ATCCBAA-1707).