• Electrical & Electronic Materials
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• v.8 no.6
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• pp.787-794
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• 1995

To improvement the magnetic and frequency properties of YIG(Yttrium-Iron Garnet) in microwave region, it is investigated that the effect of $Al^{3+}$ ions on magnetic and frequency characteristics of YIG, using samples of basic YIG composition( $Y_{3}$F $e_{5}$ $O_{l2}$) added with A1$_{2}$ $O_{3}$ from 0 to 2.5 [mol%]. The measurment is conducted mainly for the structural properties and magnetical properties. The structural properties is measured using SEM(Scanning Electro Microscope), EDX(Energy-dispersive X-ray spectrometer) and XRD(X-ray diffraction equipment). The magnetical properties is measured with B-H curve tracer and impedance analyzer. As a result, it is confin-ned that the effect of eddy current loss is minimized while maintaining high saturation flux density of YIG, when YIG is added with 0.5 [mol%] of A1$_{2}$ $O_{3}$.>.>.

• Journal of Pharmaceutical Investigation
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• v.18 no.4
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• pp.175-180
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• 1988

The role and effect of aluminum tristearate in microencapsulation were investigated based on the dispersion system of ethambutol hydrochloride in acetone-liquid paraffin. Eudragit RS was used as a wall-forming material. Eudragit RS microcapsules prepared using aluminum tristearate were uniform, free-flowing particles. The phase diagram of ethambutol hydrochloride-Eudragit RS-aluminum tristearate indicated that spherical microcapsules ranging from 250 to 1400 ${\mu}m$ in diameter could be prepared only in a very limited region. Instrumental analysis using an energy dispersive-type X-ray microanalyser and a scanning electron microscope showed that aluminum tristearate was localized near the surface of microcapsules. From these results, it was presumed that aluminum tristearate reduced the phase tension between Eudragit microcapsules and liquid paraffin. The dissolution rates of ethambutol hydrochloride from Eudragit RS microcapsules were consideraly lower than those from ethambutol hydrochloride powders and decreased as the amount of aluminum tristearate decreased.

• Korean Journal of Materials Research
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• v.4 no.7
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• pp.741-749
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• 1994

The planar solid oxide fuel cell(SOFC) contains several ceramic materials depending on its structure and has rdfractory metal parts for manifolds, shrouds and current leads. Among ceramic materials for planar SOFC, joining of lanthanum chromite separator and yttria stabilized zirconia(YSZ) electoyte in planar SOFC stack to give strong gas tight seals is necessary for satisfactory operation and high performance. Nevertheless, for planar SOFC/sub s/, how to seal the cell stack and gas manifold remains as one of the unsolved problems. Therefore, in this study. we investigated the joining of sintered lanthanum chromite and YSZ pellets using unsintered lanthanum chromite green films as sealent. Scanning electron microscopy(SEM) and energy dispersive X-ray analysis(EDX) revealed that Ca in the sealing material diffused and dissolved into YSZ and sintered lanthanum chromite, and unsintered lanthanum chromite green films reacted with YSZ to from a new phase at the interface. Also, the densification of unsintered lanthanum chromite green films was inpeded by the Ca migration.

• Journal of the Korean Society of Industry Convergence
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• v.22 no.6
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• pp.649-655
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• 2019

Fracture behaviors of SCM435 high strength bolt have been studied including macroscopic and microscopic fracture observation, Energy Dispersive X-ray Spectroscopy, Vickers hardness test and applied stress evaluation. cracks (ratchet marks) were generated by the repetitive loads acting on the bolts, initial stress of bolt and the stress concentration. The applied stress was found to be slightly higher than the fatigue limit of the material. The initial stress of bolt must be removed, and the mold temperature during the process must be maintained by room temperature. Bolts are recommended to be peened to improve fatigue limit.

• Mass Spectrometry Letters
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• v.4 no.3
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• pp.51-54
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• 2013

Isotopic analysis using thermal ionization mass spectrometry coupled with scanning electron microscopy (SEM-TIMS) was performed to determine the isotopic ratios of uranium contained in micro-particles in the 6th Nuclear Signatures Interlaboratory Measurement Evaluation Programme (NUSIMEP-6) sample. Elemental analysis by energy dispersive X-ray spectroscopy (EDS) was conducted on uranium-bearing mirco-particles, which were transferred to rhenium filaments for TIMS loading using a micromanipulation system in a SEM. A multi-ion-counter system was utilized to detect the ion signals of the four isotopes of uranium simultaneously. The isotope ratios of uranium corrected by bracketing using a reference material showed excellent agreement with the certified values. The measurement accuracy for $n(^{234}U)/n(^{238}U)$ and (b) $n(^{235}U)/n(^{238}U)$ was 10% and 1%, respectively, which met the requirements for qalification for the NetWork of Analytical Laboratories (NWAL).

• Korean Journal of Chemical Engineering
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• v.35 no.12
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• pp.2379-2383
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• 2018

We report a facile one-pot aqueous-phase synthesis of PdAu bimetallic nanoparticles with different Pd/Au ratio. The synthesis was conducted by co-reduction of Pd and Au precursor using ascorbic acid as a reducing agent and in the presence of polyallylamine hydrochloride (PAH). By high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) and energy-dispersive X-ray spectrometry (EDS) analyses, we found that the synthesized nanoparticles had an onion-like core/shell/shell/shell structure with Au-rich core, Pd-rich shell, Au-rich shell, and Pd shell, respectively. We also investigated the catalytic performance of the synthesized PdAu nanoparticles toward hydrogen peroxide generation reaction.

• Progress in Superconductivity and Cryogenics
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• v.25 no.4
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• pp.1-4
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• 2023

Recently, a claim of material, named LK-99 (a lead apatite-based compound), exhibiting a superconducting transition temperature of over 400 K under standard atmospheric pressure, was reported [1, 2]. This claim has generated considerable attention from scientists worldwide. Here, we synthesized five LK-99 samples following the method detailed in the original papers [1, 2], and measured structural and resistivity data for each of these samples. The structure of the synthesized samples (P6₃/m, a=9.82 Å , c=7.34 Å ) was very close to the reported one. Contrary to the report, however, no hint of room-temperature superconductivity was noted from any of the samples. The results of Energy-dispersive X-ray spectroscopy (EDXS) measurements demonstrate that the atomic distribution in the sample was inhomogenous, and unreacted precursors were included in the samples. To investigate the intrinsic superconducting properties of LK-99, we propose to synthesize samples having high structural purity and chemical uniformity.

• Journal of Conservation Science
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• v.34 no.4
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• pp.305-311
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• 2018

The yellow crystalline material present in yellow and green glass beads excavated from sites in the Baekje region of Korea was previously analyzed through scanning electron microscopy with energy dispersive spectroscopy and X-ray diffraction, revealing that the yellow crystalline material was $PbSnO_3$. This material is a pigment that is rarely seen in the Korean peninsula. Furthermore, some studies have been published on the provenance of lead in this material, which revealed no relationship to Korea, China, or Japan. In this study, we collected all accessible results of analyses on the lead isotope ratio of yellow and green glass beads excavated from the Korean peninsula, specifically from 7 sites in the Baekje region(located in the vicinity of Seoul, Wanju, Hwaseong, Osan, Gongju, Buyeo, and Iksan) and 2 sites in the Silla region(located in the vicinity of Gyeongju and Changnyeong). We subsequently investigated the lead provenance of the opacifying agents in the glass beads through comparison with the current extent of the galena data accumulated for the East Asian region, including Korea, China, and Japan, and for Thailand(Kanchanaburi Province), Southeast Asia. Our analysis determined that the lead provenance of the glass beads excavated from the Korean peninsula was Thailand(Kanchanaburi Province). Beyond our results, further studies should seek to determine the production sites of the glass beads. Obtaining and comparing the scientific analyses of glass beads from India and Southeast Asia would enable research on the glass beads trade through the maritime silk road.

• Textile Coloration and Finishing
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• v.30 no.3
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• pp.168-179
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• 2018

The modified surface of specialty carbon black(SCB) is one of the main technical factors for producing a uniform color and stable dispersion. In this work, the carboxylation or sulfonation process of SCB was used to improve the dispersive properties of hydrophilic solvents such as 1,6-hexanediol and propylene glycol monomethyl ether acetate(PGMEA). The results showed that the color strength of SCB DC2500G changed little with a range of 0.128~0.941(${\Delta}E$) compared to other SCB DC2500G material. In contrast, in the case of SCB EG410, there was a uniform color value with a range of 0.144~0.252(${\Delta}E$). Also, in our experiments, a modified SCB was confirmed by printing ink material as a melt coating paper. It may be possible that the SCB EG410 material can be advantageous as a gravure ink product. Finally, the modified SCB obtained from this research will have a large impact on the industry as a potential material for toners, paint, rubber, fillers, and other carbon black additives.

• Journal of Korean Society of Water and Wastewater
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• v.32 no.5
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• pp.399-409
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• 2018

Prussian blue is known as a superior material for selective adsorption of radioactive cesium ions; however, the separation of Prussian blue from aqueous suspension, due to particle size of around several tens of nanometers, is a hurdle that must be overcome. Therefore, this study aims to develop granule type adsorbent material containing Prussian blue in order to selectively adsorb and remove radioactive cesium in water. The surface of granular activated carbon was grafted using a covalent organic polymer (COP-19) in order to enhance Prussian blue immobilization. To maximize the degree of immobilization and minimize subsequent detachment of Prussian blue, several immobilization pathways were evaluated. As a result, the highest cesium adsorption performance was achieved when Prussian blue was synthesized in-situ without solid-liquid separation step during synthesis. The sample obtained under optimal conditions was further analyzed by scanning electron microscope-energy dispersive spectrometry, and it was confirmed that Prussian blue, which is about 9.7% of the total weight, was fixed on the surface of the activated carbon; this level of fixing represented a two-fold improvement compared to before COP-19 modification. In addition, an elution test was carried out to evaluate the stability of Prussian blue. Leaching of Prussian blue and cesium decreased by 1/2 and 1/3, respectively, compared to those levels before modification, showing increased stability due to COP-19 grafting. The Prussian blue based adsorbent material developed in this study is expected to be useful as a decontamination material to mitigate the release of radioactive materials.