• Journal of the Korean Crystal Growth and Crystal Technology
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• v.32 no.1
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• pp.7-11
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• 2022

Recently, Hanmi Gemological Institute & Laboratory (HGI) had an opportunity to examine 5 transparent synthetic moissanite. The round brilliants ranged from 0.93 to 0.96 ct and had a colorless, pink, yellow, blue, and red color. Advanced testing results, including Fourier-transform infrared (FTIR) and Raman spectroscopy, identified all the specimens as synthetic moissanite. Under the microscope, all samples except the colorless were confirmed to be a synthetic moissanite coated with a colored film. EDXRF chemical analysis detected very weak X-ray fluorescence peak characteristics of Ca, Ti, and Co in the colored samples. These features were not detected in the colorless sample. Raman spectroscopy investigation was unable to detect the 1332 cm^-1 (produced by sp³ bonding of carbon atoms) or the ~1550 cm^-1 (produced by graphite-related sp² bonding) peak in the colorless sample. The SEM image of the colorless sample showed no indication of a coating. The TEM image of the colorless sample revealed the presence of a 3~8 nm thick layer on the moissanite. Moreover, from the corresponding STEM Z-contrast image combined with the energy-dispersive X-ray spectroscopy (EDX) line profiles and EDX elemental maps, this layer was estimated to be carbon, silicon and oxygen.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.5
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• pp.371-380
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• 2013

Though MBR process has many advantages, the greatest risk factors in operating MBR process are occurrence of membrane fouling and decrease of flux. It is very difficult to find exact mechanism due to complex influence by many effects, although there have been recently many studies of membrane fouling. The purposes of this study are firstly evaluating bioreactor of lab-scale and micro-filtration hollow fiber membrane, secondly investigating correlation between foulants affecting membrane performance and membrane fouling, and lastly evaluating various parameters affecting fouling and applicability of membrane fouling reducer. This study found that TMP was increasing rapidly and showed 0.32 bar and the average of flux was 88 LMH. EPS concentration tends not to change much above MLSS concentration (6,000 mg/L). However, EPS concentration variation is wide below MLSS concentration (6,000 mg/L). Also, from results of membrane surface condition and element analysis using SEM/EDX, carbon and fluorine were founded to be the highest percentage in membrane because of characteristics of membrane material. In operating continuously, inorganic fouling was generated by increase of these inorganic substances such as $Al^{3+}$ and $Mg^{2+}$. Lastly, the best filtration performance was obtained for 0.03 mg MFR/mg MLSS by results of particle size, zeta potential, $SCOD_{cr}$, EPS and MLSS concentration.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.9
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• pp.1284-1288
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• 2009

Identification of various inorganic compound crystals contained in solar salts, which are produced from 12 areas of Jeonnam, was firstly made by the X-ray diffraction (XRD) technique. The analysis of the XRD spectra was carried out on the basis of Joint Committee on Powder Diffraction Standards (JCPDS) data and the results of Energy Dispersive X-ray Spectrometer (EDX) measurements. In particular, the analysis of the XRD spectra supported that each solar salt contains $Na_2S$ (Shinan Jeungdo and Sinui), $KMgCl_3$ (Shinan Bigeum), $Ca(ClO_3)_2$ (Shinan Docho), $CaAl_4O_7$ (Haenam Songji), $CaSiO_3$ and $CaCl_2$ (Goheung) as inorganic compound crystals, which have not been reported for the solar salts. Also, the XRD results indicated that the solar salts maintain a cubic NaCl crystal structure without any change of lattice parameters etc. However, it was shown in the Field Emission Scanning Electron Microscope (FE-SEM) images that an external form of the solar salts has a lamination layer shape of a cubic structure, which is different from a simple cubic form for the purified salts and the reagent NaCl.

• Analytical Science and Technology
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• v.19 no.6
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• pp.460-467
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• 2006

Carbon-coated $TiO_2$ was prepared by $CCl_4$ solvent mixing method with different heat treatment temperature (HTT). Since the carbon layers derived from pitch on the $TiO_2$ particles were porous, the carbon-coated $TiO_2$ sample series showed a good adsorptivity and photo decomposition activity. The BET surface area was decreased by the increasing of the heat treatment temperature. The SEM results present to the characterization of surface texture on the carbon-coated $TiO_2$ sample and carbon distributions on the surfaces for all the materials used. The main elements of C, O and Ti were shown from EDX spectra. And the quantity of these elements is very rich in the samples. From XRD data, the pristine anatase peaks were observed in the X-ray diffraction patterns for the carbon-coated $TiO_2$ at the different HTTs. However, the rutile peaks were observed for the carbon-coated $TiO_2$ at HTT of 1073 K and 1123 K. Finally, the excellent photocatalytic activity of carbon-coated $TiO_2$ with UV-vis spectra between absorbance and time could be attributed to the homogeneous coated carbon on the external surface and structural phase transform, and the photocatalytic activity was decreased by the increasing of the HTT.

• Analytical Science and Technology
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• v.20 no.4
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• pp.279-288
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• 2007

We have studied a method for the preparation of $ACF/TiO_2$ composites involving the penetrationof titanium n-butoxide (TNB) solution into activated carbon fiber. It was focused on the characterization of $TiO_2$ formed in prorous carbon was which increased with surface functional groups by hydrochloric acid treatment. The conversion of TNB to $TiO_2$ for the acid treatment effect must be important for the preparationof $ACF/TiO_2$ composites. From the characterization of surface properties, both the BET surface area and the total pore volume decreased as the distribution of $TiO_2$ on the activated carbon fiber surfaces after acid treatments.The changes in XRD pattern showed the typical anatase type on $ACF/TiO_2$ composite for the sample named FT, FT1 and FT2 treated with 0.05, 0.1 and 0.5 M, respectively. However, XRD patern of FT3 treated with 0.5M showed mixed amatase-rutile structure. According to the results of SEM micrographs, the titanium complexe particles were irregularly distributed around carbon. And some large clusters were found when an amount of acid treatment increased. The EDX results of $ACF/TiO_2$ composites showed the presence of C, O and P with strong Ti peaks. Finally, the excellent photocatalytic activity of the $ACF/TiO_2$ composites between relative concentration($c/c_o$) of MB (methylene blue) and UV irradiation time could be attributed to the both effects between photocatalysis of the formation of titania complexes and adsorptivity of the activated carbon fiber.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.11a
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• pp.44.1-44.1
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• 2009

본 연구에서는 Sn과 Mg를 Cu-Fe-P 합금계에 첨가 하였을 때 합금의 미세조직과 물리적 특성에 미치는 영향을 조사하였다. Cu-Fe-P 합금에 Sn과 Mg를첨가 함으로써 생성된 석출상과 합금의 미세조직, 기계적 성질 및 전기전도도를 조사하였다. 합금성분은 OES로 분석하였으며 SEM 및 EDX로 미세 석출상이생성됨을 확인하였다. 본연구를 통하여 Cu-Fe-P 합금계에 Sn과 Mg를 적절히 첨가 함으로써 고강도-고전도도의 동합금 제조가 가능함을 확인하였다.

• Journal of the Korean Ceramic Society
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• v.28 no.10
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• pp.793-802
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• 1991

The multicrystalline machinable ceramics was fabricated by melting method using domestic pyrophyllite. After determination of optimum crystallization temperature and time from results of DTA, XRD and SEM, base glasses were heat treated by 2-step schedule. Main crystalline phases identified by XRD, EDX were Na-fluorophlogopite, ${\beta}$-spoduemen and ${\alpha}$-cordierite, and the crystallization condition of these crystals was varied with chemical composition, thermal history and nucleation agents. The thermal, chemical properties of prepared samples were excellent.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.481-481
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• 2013

Chemical bath deposition (CBD) 기술에 의해 slide glass 기판 위에 CdS 박막을 적층 형성하였다. 적층된 박막들은 CdCl2와 thiorea (H2NCSNH2)를 증류수와 혼합 시dipping의 온도 조건, pH 조건, 시간 및 횟수를 달리하여 균일한 표면이 형성되도록 하였다. 적층된 박막은 $200^{\circ}C$ 이상의 고온에서 annealing하여 결정화하였다. 적층한 박막은 결정화 요인들을 XRD, FE-SEM, AFM, EDX, UV-Vis spectroscopy를 통해 조사하였다. 형성된 박막은 포토레지스터로 활용될 가능성을 조사하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.284-284
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• 2013

최근연구에 의하면 가시광선에 활성을 띄는 TiO2 개발은 중요한 연구 과제이다. 우리는 몇 가지 아민류를 이용해 수열합성법으로 TiO2에 질소를 도핑 함으로써 그 가시광선 활성을 연구하였다. 그 특성연구로서 XRD, SEM, TEM을 통해 구조와 morphology을 나타내었으며, EDX와 XPS를 통해 질소도핑 유무를 밝혔다. UV-Visible 분광기를 통해서 시료 각각의 가시광선영역에서의 흡수 유무를 확인 하였으며, 마지막으로 가시광선 영역에서 광촉매 활성을 알아보기 위해서, 광원으로 Xe-lamp를 이용, methylene blue를 분해해 그 농도를 분석하여 가시광활성을 비교 분석하였다.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.909-914
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• 2004

This study investigate the cause analysis on fracture of dropper clamp in catenary system. Dropper clamp is using as a holder between messenger wire and contact wire in catenary system. To analyze the cause analysis on fracture of dropper clamp, we have conducted experiment such as tension withstand strength test, holding strength test of a new products, SEM and EDX of field fractured specimens.