• Journal of the Korean Society of Radiology
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• v.84 no.5
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• pp.1110-1122
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• 2023

Purpose This study aimed to assess the variability of transrectal shear wave elastography (SWE) using a designed phantom. Materials and Methods In a phantom, the SWE values were examined by two radiologists using agarose and emulsion silicone of different sizes (1, 2, and 3 cm) and shapes (round, cubic) at three depths (1, 2, and 3 cm), two region of interest (ROI) and locations (central, peripheral) using two ultrasound machines (A, B from different vendors). Variability was evaluated using the coefficient of variation (CV). Results The CVs decreased with increasing phantom size. Significant changes in SWE values included; agarose phantom at 3 cm depth (p < 0.001; machine A), 1 cm depth (p = 0.01; machine B), emulsion silicone at 2 cm depth (p = 0.047, p = 0.020; both machines). The CVs increased with increasing depth. Significant changes in SWE values included; 1 cm agarose (p = 0.037, p = 0.021; both machines) and 2 cm agarose phantom (p = 0.047; machine A). Significant differences in SWE values were observed between the shapes for emulsion silicone phantom (p = 0.032; machines A) and between ROI locations on machine B (p ≤ 0.001). The SWE values differed significantly between the two machines (p < 0.05). The intra-/inter-operator agreements were excellent (intraclass correlation coefficient > 0.9). Conclusion The phantom size, depth, and different machines affected the variability of transrectal SWE.

• Archives of Metallurgy and Materials
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• v.65 no.4
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• pp.1317-1322
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• 2020

The present study investigated various thermodynamic parameters, microstructures and electrochemical behaviors of TiMoVCrZr and Ti-rich TiMoVCrZr high-entropy alloys (HEAs) prepared by vacuum arc remelting. The microstructures of the alloys were analyzed using X-ray diffraction (XRD) analysis, field emission scanning electron microscopy (FE-SEM), and potentiodynamic polarization tests. The determined thermodynamic values of the Ω-parameter and the atomic size difference (δ) for the HEAs were determined to be in the range of Ω ≥ 1.1, and δ ≤ 6.6% with valance electron configuration (VEC) ≤ 5.0, suggesting the HEAs were effective at forming solid solutions. XRD patterns of the equiatomic Ti₂₀Mo₂₀V₂₀Cr₂₀Zr₂₀ HEA revealed four phases consisting of the body centered cubic1 (BCC₁), BCC₂, hexagonal close-packed (HCP), and intermetallic compound Cr₂Zr phases. Three phases were observed in the XRD patterns of Ti-rich Ti₄₀Mo₁₅V₁₅Cr₁₅Zr₁₅ (BCC, HCP, and Cr₂Zr) and a single BCC phase was observed in Ti-rich Ti₆₀Mo₁₀V₁₀Cr₁₀Zr₁₀ HEAs. The backscattered-electron (BSE) images on the equiatomic Ti₂₀Mo₂₀V₂₀Cr₂₀Zr₂₀ HEA revealed BCC and HCP phases with Cr₂Zr precipitates, suggesting precipitation from the HCP solid solution during the cooling. The micro-segregation of Ti-rich Ti₆₀Mo₁₀V₁₀C₁₀Zr₁₀ HEAs appeared to decrease remarkably. The alloying elements in the HEAs were locally present and no phase changes occurred even after additional HIP treatment. The lowest current density obtained in the polarization potential test of Ti-rich Ti₄₀Mo₁₅V₁₅Cr₁₅Zr₁₅ HEA was 7.12×10^-4 mA/cm² was obtained. The studied TiMoVCrZr HEAs showed improved corrosion characteristics as compared to currently available joint replacement material such as ASTM F75 alloy.

• Applied Chemistry for Engineering
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• v.31 no.1
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• pp.43-48
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• 2020

Fe₂O₃ nanoparticles with the mixed structure of cubic and nanorod were synthesized by precipitation, hydrothermal, sol-gel method, etching process and heat treatment. Fe₂O₃/TiO₂ core-shell (CS) of type Fe₂O₃@TiO₂ composite was fabricated on a 20 nm nanolayer of TiO₂ coated on the surface of Fe₂O₃ nanoparticles. Fe₂O₃/TiO₂ yolk-shell (YS) composite was prepared by chemical etching and heat treatment of Fe₂O₃/TiO₂ CS nanoparticles. Physical properties of Fe₂O₃, Fe₂O₃@TiO₂ CS and Fe₂O₃@TiO₂ YS nanoparticles were characterized by FE-SEM, HR-TEM and X-ray diffraction. The solar reflectance, commission internationale de l'Elcairage (CIE) color coordinate and heat shield temperatures of Fe₂O₃, CS and YS type Fe₂O₃@TiO₂ pigments filled with poly acrylate (PA) paints were investigated by UV-Vis-NIR spectrometer and homemade heat shield temperature measuring device. The Fe₂O₃@TiO₂ YS red pigment filled PA composite exhibited excellent near infrared light reflecting performance and also reduced the heat shield temperature of 13 ℃ than that of Fe₂O₃ filled counterparts.

• Korean Journal of Mineralogy and Petrology
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• v.33 no.3
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• pp.251-258
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• 2020

Single crystal of fully dehydrated and partially Ca²⁺-exchanged zeolites A (|Ca₄Na₄|[Si₁₂Al₁₂O₄₈]-LTA) was brought into contact with Se in fine pyrex capillary at 523 K for 5 days. Crystal structure of Se-sorbed |Ca₄Na₄|[Si₁₂Al₁₂O₄₈]-LTA has been determined by single-crystal X-ray diffraction techniques at 294 K in the cubic space group $Pm{\bar{3}}m$ (a = 12.2787(13) Å). The crystal structure of yellow |Ca₄Na₄Se₄|[Si₁₂Al₁₂O₄₈]-LTA has been refined to the final error indices of R₁/wR₂ = 0.0960/0.3483 with 327 reflections for which F_o > 4s(F_o). In this structure, 4 Na⁺ and 4 Ca²⁺ ions fill every 6-ring site: These ions are all found at three crystallographic positions, on 3-fold axes equipoints of opposite 6-rings. Selenium atoms are found at three crystallographically distinct positions: 2 Se atoms per unit cell at Se(1) are located opposite 6-rings in the sodalite cavity (Se(1)-Na(1) = 2.53(5) Å) and 1 at Se(2) opposite 4-rings (Se(2)-O(1) = 2.76(10) Å) and 1 at Se(3) opposite 6-rings in the large cavity (Se(3)-Na(1) = 2.48(5) Å). Two molecular of Se₂ (Se(1)-Se(1) = 2.37(7) or 2.90(8) Å and Se(2)-Se(3) = 2.91(5) ) Å) are found in all sodalite cavity and large cavity. Other clusters such as Se₄ and Se₈ could be existed in large cavity. The inter-selenium distances turned out to be longer that of gases Se₂ molecule.

• Journal of Sensor Science and Technology
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• v.11 no.5
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• pp.309-318
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• 2002

A stoichiometric mixture of evaporating materials for $CdIn_2S_4$ single crystal thin films was prepared from horizontal electric furnace. To obtain the single crystal thin films, $CdIn_2S_4$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the Hot Wall Epitaxy (HWE) system. The source and substrate temperatures were $630^{\circ}C$ and $420^{\circ}C$, respectively. The crystalline structure of the single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of $CdIn_2S_4$ single crystal thin films measured with Hall effect by van der Pauw method are $9.01{\times}10^{16}\;cm^{-3}$ and $219\;cm^2/V{\cdot}s$ at 293 K, respectively. The temperature dependence of the energy band gap of the $CdIn_2S_4$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)=2.7116\;eV-(7.74{\times}10^{-4}\;eV)T^2/(T+434)$. The crystal field and the spin-orbit splitting energies for the valence band of the $CdIn_2S_4$ have been estimated to be 0.1291 eV and 0.0248 eV, respectively, by means of the photocurrent spectra and the Hopfield quasi cubic model. These results indicate that the splitting of the ${\Delta}so$ definitely exists in the ${\Gamma}5$ states of the valence band of the $AgInS_2$/GaAs epilayer. The three photocurrent peaks observed at 10K areascribed to the $A_1$-, $B_1$-, and C1-exciton peaks for n = 1.

• Bulletin of the Korean Chemical Society
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• v.28 no.10
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• pp.1675-1682
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• 2007

Large colorless single crystals of faujasite-type zeolite with diameters up to 200 μm have been synthesized from gels with the composition of 3.58SiO2:2.08NaAlO2:7.59NaOH:455H2O:5.06TEA:1.23TCl. Two of these, colorless octahedron about 200 μm in cross-section have been treated with aqueous 0.1 M TlC2H3O2 and KNO3 in order to prepare Tl+- and K+-exchanged faujasite-type zeolites, respectively, and then determined the Si/Al ratio of the zeolite framework. The crystal structures of |Tl71|[Si121Al71O384]-FAU and |K53Na18|[Si121Al71O384]-FAU per unit cell, a = 24.9463(2) and 24.9211(16) A, respectively, dehydrated at 673 K and 1 × 10-6 Torr, have been determined by single-crystal X-ray diffraction techniques in the cubic space group Fd m at 294 K. The two single-crystal structures were refined using all intensities to the final error indices (using only the 905 and 429 reflections for which Fo > 4σ(Fo)) R1/R2 = 0.059/0.153 and 0.066/0.290, respectively. In the structure of fully Tl+-exchanged faujasite-type zeolite, 71 Tl+ ions per unit cell are located at four different crystallographic sites. Twenty-nine Tl+ ions fill site I' in the sodalite cavities on 3-fold axes opposite double 6-rings (Tl-O = 2.631(12) A and O-Tl-O = 93.8(4)o). Another 31 Tl+ ions fill site II opposite single 6-rings in the supercage (Tl-O = 2.782(12) A and O-Tl-O = 87.9(4)o). About 3 Tl+ ions are found at site III in the supercage (Tl-O = 2.91(6) and 3.44(3) A), and the remaining 8 occupy another site III (Tl-O = 2.49(5) and 3.06(3) A). In the structure of partially K+-exchanged faujasite-type zeolite, 53 K+ ions per unit cell are found at five different crystallographic sites and 18 Na+ ions per unit cell are found at two different crystallographic sites. The 4 K+ ions are located at site I, the center of the hexagonal prism (K-O = 2.796(8) A and O-K-O = 89.0(3)o). The 10 K+ ions are found at site I' in the sodalite cavity (K-O = 2.570(19) A and O-KO = 99.4(9)o). Twenty-two K+ ions are found at site II in the supercage (K-O = 2.711(9) A and O-K-O = 94.7(3)o). The 5 K+ ions are found at site III deep in the supercage (K-O = 2.90(5) and 3.36(3) A), and 12 K+ ions are found at another site III' (K-O = 2.55(3) and 2.968(18) A). Twelve Na+ ions also lie at site I' (Na-O = 2.292(10) and O-Na-O = 117.5(5)o). The 6 Na+ ions are found at site II in the supercage (Na-O = 2.390(17) A and O-Na-O = 113.1(11)o). The Si/Al ratio of synthetic faujasite-type zeolite is 1.70 determined by the occupations of cations, 71, in two single-crystal structures.

• Journal of the Korean earth science society
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• v.38 no.7
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• pp.511-521
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• 2017

This study analyzes Two-dimensional video disdrometer (2DVD) data while summer 2011-2012 in Daegu region and compares with Marshall and Palmer (MP) distribution to find out statistical characteristics and characteristics variability about drop size distribution (DSD) of Daegu region. As the characterize DSD of Daegu region, this study uses single moment parameters such as rainfall intensity (R), reflectivity factor (Z) and double moment parameters such as generalized characteristics number concentration ($N{_0}^{\prime}$) and generalized characteristics diameter ($D{_m}^{\prime}$). Also, this study makes an assumption that DSD function can be expressed as general gamma distribution. The results of analysis show that DSD of Daegu region has ${\log}_{10}N{_0}^{\prime}=2.37$, $D{_m}^{\prime}=1.04mm$, and c =2.37, ${\mu}=0.39$ on average. When the assumption of MP distribution is used, these figures then end up with the different characteristics; ${\log}_{10}N{_0}^{\prime}=2.27$, $D{_m}^{\prime}=0.9mm$, c =1, ${\mu}=1$ on average. The differences indicate liquid water content (LWC) of Daegu distribution is generally larger than MP distribution at equal Z. Second, DSD shape of Daegu distribution is concave upward. Other important facts are the characteristics of Daegu distribution change when Z changes. DSD shape of Daegu region changes concave downward (c =2.05~2.55, ${\mu}=0.33{\sim}0.77$) to cubic function-like shape (c =3.0, ${\mu}=-0.13{\sim}-0.33$) at Z > 45 dBZ. 35 dBZ ${\leq}$ Z > 45 dBZ group of Daegu distribution has characteristics similar to maritime cluster of diverse climate DSD study. However, Z > 45 dBZ group of Daegu distribution has a difference from the cluster.

• Magazine of the Korean Society of Agricultural Engineers
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• v.11 no.4
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• pp.1798-1802
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• 1969

The experiment was carried out as one of the basic studies to improve the alkali-resistance of cement mortars and it was conducted to investigate some propetties of mortars relating to weight losses when exposed to 0.1 N salution of sodium hydroxide. The experiment and the results obtained are summarized as follow; 1. The specimens used in this experiment were made of 5 centi-meter cubes of mortar having such various ratios of mix by weight as 1 : 1, 1 : 3, 1 : 5, 1 : 7 and 1 : 10. 2. Physical tests included compressive strengths at 7 days, 28 days, 3 months, and 6 month, and 5 hour boiling absorption test. 3. In alkali test, every specimen was immersed into 0.1 N solutions of sodium hydroxide. The specimens exposed to the alkali solution were weighed to determine the weight losses of the alkail-corroded at one week interval for 7 week's exposure and the old alkali solutions were also changed to fresh solutions when weighed the weight losses by alkali attack at one week interval. 4. According to the alkail test after 7 week's exposure, no weight losses were observed on ratios of mix 1:1 and 1:3 and slight weight losses occurred on ratios of mix 1:5 and 1:7, but relatively large amount of weight losses were showed by 36.6 per-cent on ratios of mix 1:10. It was also found that the weight losses of the alkali-corroded were extremely lower than those of the acid-corroded at the some concentrations as 0.1 N of solutions. 5. In order to make better quality of alkali-resistant mortar it might recomend that a 1:7 mix or richemixes, use of small amount of mixing water for watertight, 20 per cent or less absorption by 5 hour boiling 1,600 kirogram per cubic meters or denser densities by absolute dry base are available for physical properties of mortar. It could conclude acid-resistant mortars were so high alkali-resistant, that it is expected to make and improve the acid-resistant mortars for getting rid of damages by alkali attack.

• Korean Journal of Crystallography
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• v.3 no.1
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• pp.9-22
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• 1992

Two crystal structures of bromine sorption complexes of vacuum dehydrated Cd(ll)-exchanged zeolite A have been determined by single-crystal xray diffraction techniques in the cubic space group Pm3m at 21(1) ℃. Both crystals were ion exchanged in flowing streams of exchange solution In which mole ratio of Cd(NO3)2 and Cd(OOCCH3)B was 1:1 with a total concentration of 0.05 M. First crystal was dehydrated at 450℃ and 2 ×10-6 Torr for two days. Second crystal was dehydrated at 650℃ and 2 ×10-6 Torr for two days. Both crystals were then treated with 160 Torr for two days. Second crystal was dehydrated at 650℃ and 2 × 10-6 Torr for two days. Both crystals were then treated with 160 Torr of zeolitically dried bromine vapor at 24℃. Full-matrix least-squares refinements of toe first crystal(a: 12.250(1) A )· and the second crystal(a: 12.204(2) A ) have contecoed to final error indices, Rl:0.075 and Ra:0.079 with 212 reflections, and Rl : 0.089 and Ra = 0.078 with 128 reflections, respectively, for which I >3σ(I). Crystallographic analyses of both crystals show that six Cd2+ ions are located on two different threefold axes of unit cell associated with 6-ring oxygens. Each 4.5 Cd2+ ion is recessed ca.0. 441 A Into the large cavity to complex either with Brsor with Br3from the (111) plane of 0(3), whereas each 1.5 Cd2+ ions recessed ca. 0.678 A into we sodalite unit. Approximately 1.5 Br5-and 1.5 Br3-ions are sorbed per unit cell. Each Brsion interacts and stabilized by complexing with two Cd2+ ions and framework oxide ions, while each Br3ion interacts with one Cd2+ ion and framework oxide ions. Because of residual water molecules the following reactions may be occurred inside of zeolite cavity:

• Tunnel and Underground Space
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• v.28 no.5
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• pp.400-425
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• 2018

This study presents the research results and current status of the DECOVALEX-2019 project Task B. Task B named 'Fault slip modelling' is aiming at developing a numerical method to simulate the coupled hydro-mechanical behavior of fault, including slip or reactivation, induced by water injection. The first research step of Task B is a benchmark simulation which is designed for the modelling teams to familiarize themselves with the problem and to set up their own codes to reproduce the hydro-mechanical coupling between the fault hydraulic transmissivity and the mechanically-induced displacement. We reproduced the coupled hydro-mechanical process of fault slip using TOUGH-FLAC simulator. The fluid flow along a fault was modelled with solid elements and governed by Darcy's law with the cubic law in TOUGH2, whereas the mechanical behavior of a single fault was represented by creating interface elements between two separating rock blocks in FLAC3D. A methodology to formulate the hydro-mechanical coupling relations of two different hydraulic aperture models and link the solid element of TOUGH2 and the interface element of FLAC3D was suggested. In addition, we developed a coupling module to update the changes in geometric features (mesh) and hydrological properties of fault caused by water injection at every calculation step for TOUGH-FLAC simulator. Then, the transient responses of the fault, including elastic deformation, reactivation, progressive evolutions of pathway, pressure distribution and water injection rate, to stepwise pressurization were examined during the simulations. The results of the simulations suggest that the developed model can provide a reasonable prediction of the hydro-mechanical behavior related to fault reactivation. The numerical model will be enhanced by continuing collaboration and interaction with other research teams of DECOLVAEX-2019 Task B and validated using the field data from fault activation experiments in a further study.