• The Korean Journal of Malacology
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• v.28 no.2
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• pp.157-164
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• 2012

The patterns in X-ray diffraction (XRD) spectroscopy provide useful clue at $29.4^{\circ}$ to discriminate two types of Akoya cultured pearl which occurs difference of surface luster. Using the optical microscope, we could be confirmed that the nareous layer of each sample consist of different crystal form. In Fourier Transform Infrared (FT-IR) Spectroscopy analysis, the nareous layer of Akoya cultured pearls with poor luster shows some peaks at 712, 699, 1435, $1444cm^{-1}$ region and these peaks depend on the Calcite. But the nareous layer of pearls with excellent luster could not observed those peaks related with Calcite, we could observed Aragonite band at 699, $1085cm^{-1}$ region. Though this result, we know that the nareous layer of Akoya cultured pearls with excellent luster is mainly composed by Aragonite. Raman bands are also clearly demonstrated to occur difference of band intensity by difference of Aragonite content. In the Scanning Electron Microscope (SEM) analysis, we found that the Akoya cultured pearl luster and surface condition is associated with internal structure.

• Macromolecular Research
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• v.11 no.4
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• pp.260-266
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• 2003

Ethylene vinyl acetate (EVA)/clay nanocomposites were synthesized by blending a solution of ethylene vinyl acetate copolymer containing 12% vinyl acetate abbreviated as EVA-12 in toluene and dispersion of dodecyl ammonium ion intercalated montmorillonite (l2Me-MMT) in N,N-dimethyl acetamide (DMAc). X-ray patterns of sodium montmorillonite ($Na^+$-MMT) and 12Me-MMT exhibited $d_{001}$ peak at $2{\theta}=7.4^{\circ}$ and $2{\theta}=5.6^{\circ}$ respectively; that is, the interlayer spacing of MMT increased by about 0.39 nm due to intercalation of dodecyl ammonium ions. The XRD trace of EVA showed no peak in the angular range of $3-10^{\circ}(2{\theta})$. In the XRD patterns of EVA/clay hybrids with clay content up to 6 wt% the basal reflection peak of 12Me-MMT was absent. leading to the formation of delaminated configuration of the composites. When the 12Me-MMT content was 8 wt% in the EVA-12 matrix, the hybrid revealed a peak at about $2{\theta}=5.6^{\circ}$, owing to the aggregation of aluminosilicate layers. Transmission electron microscopic photograph exhibited that an average size of 12-15 nm clay layers were randomly and homogeneously dispersed in the polymer matrix, which led to the formation of nanocomposite with delaminated configuration. The formation of delaminated nanocomposites was manifested through the enhancement of mechanical properties and thermal stability, e.g. tensile strength of an hybrid containing only 2 wt% 12Me-MMT was enhanced by about 36% as compared with neat EVA-12.

• Nuclear Engineering and Technology
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• v.23 no.4
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• pp.456-464
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• 1991

To investigate the thermal effects on functional properties of domestic bentonite, XRD patterns, TG /DSC curves, swelling rates and distribution coefficients of heat-treated Dong-Hae A bentonite were studied. In the XRD patterns, (001) peak disappeared at above 20$0^{\circ}C$ and Dong-Hae A was identified as Ca-bentonite through the DSC curve. The loss of swelling capacity and CEC began at 10$0^{\circ}C$. The distribution coefficients of Am-241, Co-60 and Cs-137 onto heat-treated Dong-Hae A showed negligible variance as temperature was raised and that of Sr-85 decreased at about 15$0^{\circ}C$. Reviewing these data, it was evaluated that Dong-Hae A colud be used as a buffer material at below 10$0^{\circ}C$.

• Applied Microscopy
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• v.29 no.1
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• pp.75-81
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• 1999

Optimum conditions for making the Au and Al internal standards for TEM have been determined experimentally. The Au internal standard was produced by sputter coating at 9mA for 100 seconds in low vacuum $(\leq1\times10^{-3})$. The Al internal standard was produced by evaporation coating at 7kV for 10 minutes in high vacuum $(\leq1\times10^{-5})$. Measurements of the lattice parameters of andalusite and albite feldspars with this Au internal standard resulted in errors of (a) $ \leq1.2%$ in precion and $\leq0.3%$ in accuracy for andalusite: (b) $\leq0.5%$ in precision and $\leq1.1%$ in accuracy for albite feldspars. The most significant error occurred from the measuring processes of distances and angles of electron diffraction patterns. By employing systematic procedures of measurement with high precision devices, this lattice parameter determination method utilizing the internal standard should be a good alternative to the conventional powder XRD method or the sophisticated CBED method for special samples.

• Restorative Dentistry and Endodontics
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• v.38 no.3
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• pp.134-140
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• 2013

Objectives: There has been a growing interest in glass ceramic systems with good esthetics, high fracture resistance and bonding durability, and simplified fabrication techniques using CAD/CAM. The aim of this study is to compare flexural strength before and after heat treatment of two lithium disilicate CAD/CAM blocks, IPS e.max CAD (Ivoclar Vivadent) and Rosetta SM (Hass), and to observe their crystalline structures. Materials and Methods: Biaxial flexural strength was tested according to ISO 6872 with 20 disc form specimens sliced from each block before and after heat treatment. Also, the crystalline structures were observed using field-emission scanning microscopy (FE-SEM, Hitachi) and x-ray diffraction (XRD, Rigaku) analysis. The mean values of the biaxial flexural strength were analyzed by the Mann-Whitney U test at a significance level of p = 0.05. Results: There were no statistically significant differences in flexural strength between IPS e.max CAD and Rosetta SM either before heat treatment or after heat treatment. For both ceramics, the initial flexural strength greatly increased after heat treatment, with significant differences (p < 0.05). The FE-SEM images presented similar patterns of crystalline structure in the two ceramics. In the XRD analysis, they also had similar patterns, presenting high peak positions corresponding to the standard lithium metasilicate and lithium disilicate at each stage of heat treatment. Conclusions: IPS e.max CAD and Rosetta SM showed no significant differences in flexural strength. They had a similar crystalline pattern and molecular composition.

• Journal of the Korea Institute of Building Construction
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• v.23 no.3
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• pp.231-240
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• 2023

In this research, our goal was to explore the potential use of cement mortar augmented with liquid red mud. To facilitate this, we neutralized liquid red mud(LR) - exhibiting a pH of 10-12 - using sulfuric acid to yield sulfuric acid neutralized red mud(SR). We then evaluated the flow, setting time, and compressive strength of the cement mortar combined with liquid red mud, while also performing a thorough examination of its chemical properties through X-ray diffraction(XRD) and scanning electron microscopy(SEM). The flow tests indicated a decrease in flow values for both MS-LR and MS-SR in comparison to the Plain. Analogously, the setting time for MS-LR and MS-SR was found to be abbreviated when juxtaposed with the Plain. With regards to compressive strength, MS-LR demonstrated a surge in strength at the 1-day mark, while MS-SR displayed a diminution at the 1-day and 3-day timepoints compared to the Plain. XRD analysis illustrated that after 28 days, the XRD patterns of Plain and MS-SR bore significant resemblance, though a new peak was detected in MS-LR. SEM imagery highlighted that the microstructures of Plain and MS-SR were alike, but MS-LR manifested a distinct microstructure, characterized by a finely fibrous formation. Based on these observations, we infer that the replacement of cement mortar with liquid red mud neutralized with sulfuric acid contributes to a noticeable enhancement in strength, thereby verifying its suitability for this application.

• Korean Journal of Heritage: History & Science
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• v.45 no.3
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• pp.160-173
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• 2012

Roofing tile research conducted in Korea so far is mostly related to studies on roofing tile patterns excavation report on the roof tile klin site in the aspects of archeology architecture and history of art. There have been continuous studies on kiln ground and manufacture techniques of roofing tiles. However it is difficult to find roofing tiles research based on scientific experiments. The research on this paper performs physical and chemical experimental study to understand order, manufacturing techniques and other characteristics of Chosun Dynasty roofing tiles excavated in Dongdaemun stadium. As for physical experimental study water absorption, specific gravity, whole-rock Magnetic susceptibility rate and Differential Thermal Analysis are conducted. As for chemical experimental study, neutron activation analysis(NAA), microstructure observation, X-ray diffractometry(XRD) analysis are conducted. Result of neutron activation analysis and statistical analysis on piece of roof tile 22 samples clearly show that the roofing tile samples are from different time line and places. It also shows different composition when compare average value of rare earth resources per findspots. It means roofing tiles were manufactured from clay mineral from several places. Close inspection using XRD and polarization microscope reveals that main components of roofing tiles are quartz and felspar. Mica and Illite are found partially. XRD analysis shows mullite mineral composition which occurs when roofing tile is calcined around $1000^{\circ}C$. Differential thermal analysis shows gradual exothermic peak near $900^{\circ}C$. Based on these results, it is assumed that roofing tile is made at $900{\sim}1000^{\circ}C$. result of XRD analysis shows mullite were made near $1000^{\circ}C$. in Differential Thermal Analysis shows gradual exothermic peak near $900^{\circ}C$. this results shows that roof tiles were made near 900~1000 near $1000^{\circ}C$ mean value of whole-rock Magnetic susceptibility rate. When performed comparative analysis using whole-rock Magnetic susceptibility rate average value, findspots provided no certain classification to arrange. Nonetheless low whole-rock Magnetic susceptibility rate 0.2~0.78(${\times}103$ SI unit) is found when roofing tile patterns are Pasangmun, Taesangmun, Eosangmun, Kyukjamun, Heongsunmun. Overall absorptivity is 14~21%. It is similar to 14~18% of roofing tile from Chosun Dynasty. There is only 1.4~2.5g/cm3 of roof tile sample specific gravity. The analysis finds no difference in specific gravity by findspots.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.7
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• pp.16-19
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• 2019

A thinner film has superior electrical properties and a better amorphous structure. Amorphous structures can be effective in improving conductivity through a depletion effect. Research is needed on the Schottky contact, where potential barriers are formed, as a way to identify these characteristics. $SiO_2/SnO_2$ thin films were prepared to examine the amorphous structure and Schottky contact, $SiO_2$ thin films were prepared using Ar = 20 sccm. $SnO_2$ thin films were deposited using mixed gas with a flow rate of argon and oxygen at 20 sccm, and $SnO_2$ thin films were added by magnetron sputtering and treated at $100^{\circ}C$ and $150^{\circ}C$. To identify the conditions under which the amorphous structure was constructed, the XRD patterns were investigated and C-V and I-V measurements were taken to make Al electrodes and perform electrical analysis. The depletion layer was formed by the recombination of electrons and holes through the heat treatment process. $SiO_2/SnO_2$ thin films confirmed that the pores were well formed when heat treated at $100^{\circ}C$ and an electric current was applied over the micro area. An amorphous $SiO_2/SnO_2$ thin film with heat treatment at $100^{\circ}C$ showed no reflection at $33^{\circ}\;2{\theta}$ in the XRD pattern, and a reflection at $44^{\circ}2\;{\theta}$. The macroscopic view (-30 V

• Proceedings of the KIEE Conference
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• 1995.07c
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• pp.1098-1101
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• 1995

NbTi thin films were prepared on Si wafer and Cu substrate by rf magnetron sputtering in the range of sputtering pressure $3{\times}10^{-2}$torr to $3{\times}10^{-4}$torr at room temperature. The influence of sputtering pressure and substrate type on crystallographic orientation and morphology of NbTi thin films was investigated by using X-ray diffraction(XRD) and scanning electron microscopy(SEM), respectively. And the effect of crystallographic orientation and morphology of NbTi film on electromagnetic behaviors was estimated by measuring critical current in various applied magnetic field. The film morphology changed from porous structure consisting of tapered crystallites to densely deposited film decreasing with sputtering pressure. The change of crystallographic orientation with the sputtering pressure and rf power was calculated from the texture coefficient of(002) plane based on XRD patterns. It was found that a change of texture coefficient of(002) plane increased with decreasing sputtering pressure. From observation of critical current in various applied magnetic field, we have identified that the change of critical current abruptly decrease applying with magnetic field and NbTi film produced at high sputtering pressure does not exhibit superconductivity but at low sputtering pressure shows superconductivity.

• Bulletin of the Korean Chemical Society
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• v.31 no.2
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• pp.355-359
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• 2010

A $Li[Co_{1/3}Ni_{1/3}Mn_{1/3}]O_2$ cathode was modified by applying a $ZrF_x$ coating. The surface-modified cathodes were characterized by XRD, SEM, EDS, TEM techniques. XRD patterns of $ZrF_x$-coated $Li[Co_{1/3}Ni_{1/3}Mn_{1/3}]O_2$ revealed that the coating did not affect the crystal structure of the parent powder. SEM and TEM images showed that $ZrF_x$ nano-particles were formed as a coating layer, and EDS data confirmed that $ZrF_x$ distributed uniformly on the surface the powder. Capacity retention of coated samples at high C rates was superior to that of pristine sample. However, as the coating concentration increases beyond the optimum concentration, the rate capability was deteriorated. Whereas, as the increase of coating concentration to 2.0 wt %, the cyclic performances of the electrodes under the severe conditions (high cut-off voltage, 4.8 V, and high measurement temperature, $55^{\circ}C$) were improved considerably.