• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.2
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• pp.46-52
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• 2019

This research was conducted to analyze the effects of temperature on coking characteristics of kerosene. The kerosene was heated to 600 K, 700 K, and 800 K, and the cooled samples were collected. The used copper tubes were replaced according to the temperature conditions. The liquid and copper specimens were analyzed by gas chromatography-mass spectrometry and scanning electron microscopy equipped with an energy dispersive x-ray spectrometer, respectively. The results of the analysis confirmed that a carbon deposit was formed from the coking of fuel on the inner surface of the copper specimen at a relatively high temperature (800 K) of the copper tube.

• Journal of Oral Medicine and Pain
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• v.36 no.3
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• pp.161-167
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• 2011

Sialolith is one of the most common pathologic conditions found in the salivary glands. The mechanisms responsible for the formation of sialoliths have not been elucidated so far. In this article, the chemical composition and micromorphology of a sialolith of a 58-year old female patient suffering from chronic sialoadenitis of the submandibular gland was analyzed using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). In a SEM evaluation, the highly mineralized amorphous core surrounded by lamellar and concentric structures was revealed, however no foreign body, organic material, or signs of microorganism were observed in the core of the sialolith. EDX analysis showed the central core was composed of only Ca, O and P, and that a high level of C was detected near the central area as well. These results indicated that the inorganic composition of the sialolith was hydroxyapatite crystals, and that inorganic and organic substances existed around the central cores. This study suggests that the sialolith was composed mainly of hydroxyapatite crystals and the formation of the nucleus of the sialolith in the submandibular gland duct was secondary to sialadenitis, which favors the growth of an inorganic crystalline nucleus.

• Clean Technology
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• v.19 no.3
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• pp.347-350
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• 2013

Desorption characteristics for ions adsorbed onto sericite was performed by means of $HNO_3$ solution which was selected as the best desorbing agent in the previous work. Elution of nickel ions adsorbed onto sericite using $HNO_3$ solution was confirmed by means of scanning electron microscopy (SEM) & energy dispersive X-ray spectroscopy (EDX) analysis. Desorption efficiency for nickel ions was 100% at the 20 mM of concentration. Also, nickel ions was completely desorbed within 1.0 of S/L (mg/mL) ratio which is defined as the ratio of adding amount of adsorbent and volume of desorbing agent and desorption process was quickly carried out within 60min. Finally, removal efficiency of reused sericite for nickel ions was constantly maintained until the 4th cycle.

• Korean Chemical Engineering Research
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• v.60 no.1
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• pp.151-158
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• 2022

Iron and nitrogen coordinated carbon catalyst (Fe-N-C) is the most promising non-precious metal catalyst (NPMC) studied to alternate the Pt-group oxygen reduction reaction (ORR) catalyst. In this work, Fe/N/C type catalysts are prepared by four different nitrogen precursors; N, N, N', N'-tetramethylethylenediamine (TMEDA), 1,2-ethylenediamine (EDA), m-dicyanobenzene (DCB), dicyandiamide (DCDA) which can chelate a transition metal; In addition, the catalysts conducted the pyrolysis process at four different temperatures of 700, 800, 900, 1000 ℃ to investigate the ORR activities depend on pyrolysis temperature and to find an appropriate temperature. The characterizations of catalysts were investigated by scanning electron microscope-energy dispersive X-ray spectrometer (SEM-EDS), X-ray diffraction (XRD), and element analysis (EA). The electrocatalytic activity was measured by ORR polarization, also the electron transfer number was calculated from the slope of the K-L plot. The FeNC-EDA-800 which were prepared at pyrolysis temperature of 800 ℃ with EDA showed better ORR activity than the other catalysts.

• Applied Chemistry for Engineering
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• v.31 no.2
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• pp.220-225
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• 2020

Hair is made of proteins containing various amino acids. Ultraviolet (UV) radiation is believed to be responsible for the most damaging effects of sunlight, and also plays an important role in hair aging. The purpose of this study was to investigate the changes in morphological and chemical structures after ultraviolet B (UVB) irradiation of human hair. The UVB-irradiated hair showed characteristic morphological and structural changes, compared to those of the normal hair. The result from a scanning electron microscope (SEM) equipped with an energy dispersive X-ray diffractometer (EDX) showed that the scale of UV-irradiated hair appeared to be rough and the amount of oxygen element was higher than that of the normal hair. Fluorescence and three dimensional (3D) topographical images were obtained by a confocal laser scanning microscope (CLSM). In 3D images, the green emission intensity of normal hair was much higher than that of fluorescing UVB-irradiated hair. The intensity of green emission reflects the intrinsic fluorescence of hair protein. Also, a fluorescent imaging method using fluorescamine reagent was used to identify the free amino groups resulting from a peptide bond breakage in UVB-irradiated hair. Strong blue fluorescence of UVB-irradiated hair, which indicates a very high level of amino groups, was observed by CLSM. Therefore, the fluorescamine as an extrinsic fluorescence could provide a useful tool to identify the peptide bond breakage in UVB-irradiated hair. Infrared image mapping was also employed to assess the cross-sections of normal and UVB-irradiated specimens to examine the oxidation of disulfide bonds. The degree of peak areas with strong absorbance for the disulfide mono-oxide was spread from the outside to the inside of hair. The spectroscopic techniques used alone, or in combination, launch new possibilities in the field of hair cosmetics.

• Applied Chemistry for Engineering
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• v.20 no.6
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• pp.617-621
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• 2009

Zinc oxide (ZnO) nanorods were grown on the pre-oxidized silicon substrate with the assistance of Au and the fluorine-doped tin oxide (FTO) based on the catalysts by vapor-liquid-solid (VLS) synthesis. Two types of ZnO powder particle size, 20nm, $20{\mu}m$, were used as a source material, respectively The properties of the nanorods such as morphological characteristics, chemical composition and crystalline properties were examined by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX) and field-emission scanning electron microscope (FE-SEM). The particle size of ZnO source strongly affected the growth of ZnO nanostructures as well as the crystallographic structure. All the ZnO nanostructures are hexagonal and single crystal in nature. It is found that $1030^{\circ}C$ is a suitable optimum growth temperature and 20 nm is a optimum ZnO powder particle size. Nanorods were fabricated on the FTO deposition with large electronegativity and we found that the electric potential of nanorods rises as the ratio of current rises, there is direct relationship with the catalysts, Therefore, it was considered that Sn can be the alternative material of Au in the formation of ZnO nanostructures.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.3
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• pp.73-79
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• 2003

This paper describes the characteristics of capacitor elements at self healing. Self healing events were forced to be created by the over-rated voltage of the capacitor elements. The self healing site was photographed by the Scanning Electron Microscope and the by-products of self healing were analyzed by the Energy Dispersive X-ray Spectrometer. Also the self healing site was analyzed by the Differential Scanning Calorimeter and the Fourier Transform Infrared Spectrometer. As a result, the main component of by-products due to the hum cut at self healing was carbon. The Fourier Transform Infrared analysis result of the self-healing specimen was similar to that of the virgin specimen, however, different from that of the specimen thermally treated at 500$^{\circ}C$. It was observed that heat flow peaks of virgin specimen were different from self-healing specimen by the Differential Scanning Calorimeter analysis.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.17 no.2
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• pp.127-137
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• 2019

Zr electrorefining is demonstrated herein using Zirlo tubes in a chloride-fluoride mixed molten salt in the presence of $AlF_3$. Cyclic voltammetry reveals a monotonic shift in the onset of metal reduction kinetics towards positive potential and an increase in intensity of the additional peaks associated with Zr-Al alloy formation with increasing $AlF_3$ concentration. Unlike the galvanostatic deposition mode, a radial plate-type Zr growth is evident at the top surface of the salt during Zr electrorefining at a constant potential of -1.2 V. The diameter of the plate-type Zr deposit gradually increases with increasing $AlF_3$ concentration. Scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDX) and X-ray photoelectron spectroscopy (XPS) analyses for the plate-type Zr deposit show that trace amount of Al is incorporated as Zr-Al alloys with different chemical compositions between the top and bottom surface of the deposit. Addition of $AlF_3$ is effective in lowering the residual salt content in the deposit and in improving the current efficiency for Zr recovery.

• Clean Technology
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• v.19 no.3
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• pp.320-326
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• 2013

Nano-sized PtRu-Ni/VC and PtRu-Sn/VC electrocatalysts were synthesized by a one-step radiation-induced reduction (RIR) (30 kGy) process using distilled water as the solvent and Vulcan XC-72 as the supporting material. The obtained electrocatalysts were characterized by transmission electron microscopy (TEM), scanning electron microscope energy dispersive spectroscopic (SEM-EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), respectively. The catalytic efficiency of electrocatalysts was examined for oxygen reduction, MeOH oxidation and CO stripping decreased in the following order, Hydrogen stripping : PtRu-Sn/VC > PtRu-Ni/VC > PtRu/VC$^{(R)}$ (E-TEK). MeOH oxidation : PtRu-Sn/VC > PtRu-Ni/VC > PtRu/ VC$^{(R)}$ (E-TEK). Unit cell performance : PtRu-Sn/VC > PtRu-Ni/VC > PtRu/VC$^{(R)}$ (E-TEK) catalysts.

• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.1
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• pp.89-96
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• 2023

In this paper, a ferrosilicon by-product was evaluated to confirm the feasibility of recycling it as supplementary cementitious material of ordinary Portland cement in concrete. Three different levels of replacement ratio (10 %, 20 % and 30 % of total binder) were applied to find which is the most beneficial to be used as a binder. Ferrosilicon concrete was initially assessed at setting time and compressive strength. Durability was evaluated by the resistance to chloride penetration test(RCPT) and alkali-silica reaction(ASR) with a comparison to silica fume concrete due to their similarity in chemical composition. The porosimetry and X-ray diffraction analysis along with energy dispersive X-ray spectroscopy give information on the microstructural characteristics of the ferrosilicon concrete. It was found that 10 % ferrosilicon concrete has higher strength while 20 %, 30 % have lower strength than OPC concrete. However, chemical resistance to chloride attack is higher when replacement is increased. Compared to silica fume, the durability of ferrosilicon might be less efficient however, it is obviously beneficial than OPC. High SiO₂ content in ferrosilicon results in producing more C-S-H gel which could make denser pore structure. Most of the risk of alkali silica reaction to silicate binders through length change tests was less than 0.2 %, and both mortar using ferrosilicon and silica fume showed better resistance to alkali silica reaction as the substitution rate increased.Reuse of industrial waste rather than producing highly refined additives might reduce environmental load during manufacture and save costs.