• Journal of the Korean Ceramic Society
• /
• v.43 no.5 s.288
• /
• pp.270-276
• /
• 2006

LSGM(($La_xSr_{1-x})(Ga_yMg_{1-y})O_3$) electrolyte is known to show very serious interfacial reaction with other unit cell components, especially with an anode. Such an interfacial reaction induced the phase instability of constituent component and deterioration of the unit cell performance, which become the most challenging issues in LSGM-based SOFCs. In this study, we fabricated LSGM($La_{0.8}Sr_{0.2}Ga_{0.83}Mg_{0.17}O_x$) electrolyte supported-type cell in order to avoid such interfacial problem by lowering the heat-treatment temperature of the electrode fabrication. According to the microstructural and phase analysis, there was no serious interfacial reaction at both electrolyte/anode and electrolyte/cathode interfaces. Moreover, from the electrochemical characterization of the unit cell performance, there was no distinct deterioration of the open cell voltage as well as an internal cell resistance. These results demonstrate the most critical point to be concerned in LSGM-based SOFC is either to find a proper electrode material which will not give any interfacial reaction with LSGM electrolyte or to properly adjust the processing variables for unit cell fabrication, to reduce the interfacial reaction.

• Journal of Korea Foundry Society
• /
• v.39 no.2
• /
• pp.21-25
• /
• 2019

Microstructural and corresponding hardness changes of TiFe compounds with Zr (0~6 at%) or Ce (0~3 at%) were studied using samples prepared at different solidification rates. In arc-melted (TiFe)-Zr samples, the $Fe_{23}$ $Zr_6$ and $(Ti,\;Zr)_2Fe$ phases formed in the TiFe matrix, while in the (TiFe)-Ce sample, the $CeO_2$ phase formed along the grain boundary of the TiFe matrix. As the Zr content was increased, the volume fractions of the $Fe_{23}$ $Zr_6$ and $(Ti,\;Zr)_2Fe$ phases increased, forming a network structure. Accordingly, the hardness values of the samples also increased. With a small addition of Ce of approximately 0.1 at%, the as-cast microstructure could be effectively refined, reducing the average grain boundary diameter from ${\sim}100{\mu}m$ to ${\sim}14{\mu}m$. In the rapidly solidified sample prepared through a melt-spinning method, the constituent phases were identical to those of the arc-melted samples while the grains were refined. The microstructural changes of TiFe alloys can affect the hydrogen storage ability as well as the mobility of the hydrogen atoms in the alloys.

• Nuclear Engineering and Technology
• /
• v.54 no.12
• /
• pp.4798-4808
• /
• 2022

The porous corrosion deposits (known as CRUD) adhered to the cladding have an important effect on the heat transfer from fuel rods to coolant in PWRs. The vapor film is the main constituent in the two-phase film boiling model. This paper presents a vapor film thickness correlation, associated with CRUD porosity, CRUD chimney density, CRUD particle size, CRUD thickness and heat flux. The dependences of the vapor film thickness on the various influential factors can be intuitively reflected from this vapor film thickness correlation. The temperature, pressure, and boric acid concentration distributions in CRUD can be well predicted using the two-phase film boiling model coupled with the vapor film thickness correlation. It suggests that the vapor thickness correlation can estimate the vapor film thickness more conveniently than the previously reported vapor thickness calculation methods.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.6 no.1
• /
• pp.1-12
• /
• 2001

Tidal computations of $M_2,\;S_2,\; K_1$ and $O_1$ constituents in the northeast Asian sea are presented by blending the Topex/Poseidon (T/P) altimeter data into a hydrodynamic model with $5'{\times}5'$ resolution. A series of sensitivity experiments on a weighting factor, which is the control parameter in the blending method, are carried out using $M_2$ constituent. The weighting factor is set to be in inverse proportion to the square root of water depth to reduce noises which could occur in data-assimilative model by blending T/P data. Model results obtained by blending the T/P-derived $M_2,\;S_2,\; K_1$ and $O_1$ constituents simultaneously are compared with all T/P-track tidal data; Average values of amplitude and phase errors are close to zero. Standard deviations of amplitude and phase errors are approximately 2 cm and less than 10 degrees respectively. The data-assimilative model results show a quite good agreement with T/P-derived tidal data, particularly in shallow water region (h<250m). In deep water regions, T/P-derived tidal data show unreasonable spatial variations in amplitude and phase. The data-assimilative model results differ from T/P-derived data, but are improved to show reasonable spatial variations in amplitude and phase. In addition, the T/P-blended model results are in good agreement with coastal tide gauge data which are not blended into the model.

• Economic and Environmental Geology
• /
• v.45 no.4
• /
• pp.351-363
• /
• 2012

In order to develop the evaluation techniques for the potential sulfide ore reserves, the relationships between the modal vol.%, grain sizes and textural characteristics of the constituent minerals (e.g., sulfides, oxides and skarn minerals) and the Spectral Induced Polarization (SIP) phase differences are examined for the nine rock cores collected from the Gagok Pb-Zn skarn deposit. The Gagok Pb-Zn skarn deposit occurs mainly along the intrusive contact between the Cretaceous granitic rocks and Cambrian Myobong slate and Pungchon limestone. The nine rock cores have been grouped into three showing distinctive SIP phase differences: the highest (Group I), intermediate (Group II) and lowest (Group III). In relation with the modal vol.% of minerals, Group I is characterized by higher pyrrhotite (25-38 vol.%) and amphibole (40-55 vol.%); Group II by intermediate pyrrhotite (7-13 vol.%) and higher garnet (44-68 vol.%); and lower pyrrhotite (1-7 vol.%) and higher pyroxene (24-66 vol.%) stand for Group III. Furthermore, the grains of all the major constituent minerals become smaller from Group I (<5 mm) through Group II (<2.5 mm) to Group III (<1.6 mm). In particular, the pyrrhotite contents and their grain sizes show logarithmic correlation with the SIP phase differences, Although we present here the results solely from nine samples, the systematic interrelations especially for pyrrhotite indicate the potential ability of SIP measurements as a new mine-evaluation technique for the sulfide ore reservoir.

• Journal of Powder Materials
• /
• v.9 no.6
• /
• pp.394-408
• /
• 2002

Nanostructured high strength metastable Al-, Mg- and Ti-based alloys containing different amorphous, quasicrystalline and nanocrystalline phases are synthesized by non-equilibrium processing techniques. Such alloys can be prepared by quenching from the melt or by powder metallurgy techniques. This paper focuses on one hand on mechanically alloyed and ball milled powders containing different volume fractions of amorphous or nano-(quasi)crystalline phases, consolidated bulk specimens and, on the other hand. on cast specimens containing different constituent phases with different length-scale. As one example. $Mg_{55}Y_{15}Cu_{30}$- based metallic glass matrix composites are produced by mechanical alloying of elemental powder mixtures containing up to 30 vol.% $Y_2O_3$ particles. The comparison with the particle-free metallic glass reveals that the nanosized second phase oxide particles do not significantly affect the glass-forming ability upon mechanical alloying despite some limited particle dissolution. A supercooled liquid region with an extension of about 50 K can be maintained in the presence of the oxides. The distinct viscosity decrease in the supercooled liquid regime allows to consolidate the powders into bulk samples by uniaxial hot pressing. The $Y_2O_3$ additions increase the mechanical strength of the composites compared to the $Mg_{55}Y_{15}Cu_{30}$ metallic glass. The second example deals with Al-Mn-Ce and Al-Cu-Fe composites with quasicrystalline particles as reinforcements, which are prepared by quenching from the melt and by powder metallurgy. $Al_{98-x}Mn_xCe_2$ (x =5,6,7) melt-spun ribbons containing a major quasicrystalline phase coexisting with an Al-matrix on a nanometer scale are pulverized by ball milling. The powders are consolidated by hot extrusion. Grain growth during consolidation causes the formation of a micrometer-scale microstructure. Mechanical alloying of $Al_{63}Cu_{25}Fe_{12}$ leads to single-phase quasicrystalline powders. which are blended with different volume fractions of pure Al-powder and hot extruded forming $Al_{100-x}$$(Al_{0.63}Cu_{0.25}Fe_{0.12})_x$ (x = 40,50,60,80) micrometer-scale composites. Compression test data reveal a high yield strength of ${\sigma}_y{\geq}$700 MPa and a ductility of ${\varepsilon}_{pl}{\geq}$5% for than the Al-Mn-Ce bulk samples. The strength level of the Al-Cu-Fe alloys is ${\sigma}_y{\leq}$550 MPa significantly lower. By the addition of different amounts of aluminum, the mechanical properties can be tuned to a wide range. Finally, a bulk metallic glass-forming Ti-Cu-Ni-Sn alloy with in situ formed composite microstructure prepared by both centrifugal and injection casting presents more than 6% plastic strain under compressive stress at room temperature. The in situ formed composite contains dendritic hcp Ti solid solution precipitates and a few $Ti_3Sn,\;{\beta}$-(Cu, Sn) grains dispersed in a glassy matrix. The composite micro- structure can avoid the development of the highly localized shear bands typical for the room temperature defor-mation of monolithic glasses. Instead, widely developed shear bands with evident protuberance are observed. resulting in significant yielding and homogeneous plastic deformation over the entire sample.

• Proceedings of the Korean Vacuum Society Conference
• /
• 1998.02a
• /
• pp.120-120
• /
• 1998

Boron nitride (BN) films have attracted a growing interest for a variety of t technological applications due to their excellent characteristics, namely hardness, c chemical inertness, and dielectrical behavior, etc. There are two crystalline phases 1551; of BN that are analogous to phases of carbon. Hexagonal boron nitride (h-BN) has a a layered s$\sigma$ucture which is spz-bonded structure similar to that of graphite, and is t the stable ordered phase at ambient conditions. Cubic boron nitride (c-BN) has a z zinc blende structure with sp3-bonding like as diamond, 따ld is the metastable phase a at ambient conditions. Among of their prototypes, especially 삼Ie c-BN is an i interesting material because it has almost the same hardness and thermal c conductivity as di없nond. C Conventionally, significant progress has been made in the experimental t techniques for synthesizing BN films using various of the physical vapor deposition 밍ld chemical vapor deposition. But, the major disadvantage of c-BN films is that t they are much more difficult to synthesize than h-BN films due to its narrow s stability phase region, high compression stress, and problem of nitrogen source c control. Recent studies of the metalorganic chemical vapor deposition (MOCVD) of I III - V compound have established that a molecular level understanding of the d deposition process is mandatory in controlling the selectivity parameters. This led t to the concept of using a single source organometallic precursor, having the c constituent elements in stoichiometric ratio, for MOCVD growth of 삼Ie required b binary compound. I In this study, therefore, we have been carried out the growth of h-BN thin f films on silicon substrates using a single source precursors. Polycrystalline h-BN t thin films were deposited on silicon in the temperature range of $\alpha$)() - 900 $^{\circ}$C from t the organometallic precursors of Boron-Triethylamine complex, (CZHs)3N:BRJ, and T Tris(dimethylamino)Borane, [CH3}zNhB, by supersonic molecular jet and remote p plasma assisted MOCVD. Hydrogen was used as carrier gas, and additional nitrogen w was supplied by either aDlIDonia through a nozzle, or nitrogen via a remote plasma. T The as-grown films were characterized by Fourier transform infrared spectroscopy, x x-ray pthotoelectron spectroscopy, Auger electron spectroscopy, x-ray diffraction, t transmission electron diffraction, optical transmission, and atomic force microscopy.roscopy.

• Asian Pacific Journal of Cancer Prevention
• /
• v.16 no.16
• /
• pp.7337-7342
• /
• 2015

The study aimed to investigate the profile of alkaloids in two ethyl acetate soluble fractions, namely fractions A and B from an ethanolic extract of Ficus septica leaves and cytotoxic effect on T47D breast cancer cells. Preparation of both fractions involved maceration of leaves with 70% (v/v) ethanol, filtration with $Al_2O_3$, precipitation with 0.1 N HCl, Mayer reagent, and 0.1 N NaOH, and also partition with ethyl acetate. Qualitative thin layer chromatography (TLC) was conducted to determine the profile of alkaloids in the two fractions, using alkaloid specific reagents such as Dragendorff, sodium nitrite, and Van Urk-Salkowski. Cytotoxic effects of both fractions on T47D cells were evaluated using MTT assay with a concentration series of 1.56; 3.12; 6.25; 12.5; 25 and $50{\mu}g/mL$. The TLC test showed that fractions A and B contained alkaloids with Rx values of 0.74 and 0.80 for fraction A and 0.74, 0.84, 0.92 for fraction B with regard to yohimbine using the mobile phase of n-buthanol:glacial acetic acid:distilled water (3:1:1 v/v/v). Moreover, an indole alkaloid was detected with Rx values of 0.80 and 0.84, respectively. Fractions A and B exhibited high cytotoxic effects on T47D cells with IC50 values of 2.57 and $2.73{\mu}g/mL$, respectively. In conclusion, overall the results of this study showed that fractions of Ficus septica contain alkaloids including indole alkaloid or its derivatives and possess a cytotoxic effect on T47D cells. This research supports the idea that alkaloids in F. septica have anticancer activity.

• Transactions of the Korean hydrogen and new energy society
• /
• v.24 no.3
• /
• pp.237-241
• /
• 2013

The correlation between NiO-YSZ microstructure and its electrical property used for SOFC anode was critically evaluated with image processing and direct measurement techniques. These innovative processing techniques were employed to quantify the contiguity of the anode constituent phase. The calculated contiguities were then correlated with electrical conductivity attained from 4-probe DC method. This investigation described that contiguity of nickel oxide phases of an anode has a linear relationship with its electrical conductivity. We observed that the contiguity of NiO increased from 0.18 to 0.50 then electrical conductivity attained was significantly increased from 520 S/cm to 1468 S/cm at $900^{\circ}C$.

• Korean Institute of Interior Design Journal
• /
• v.16 no.2 s.61
• /
• pp.322-330
• /
• 2007

Because 6sigma is doing innovative success In management whole, estimate that can exert direct effect in interior Design management. Therefore, this study did by purpose that 6sigma that is scientific method that do customers satisfaction by ultimate purpose acts as basic study that can heighten practical use Possibility and result of interior Design management and value by interior design standardization process. Need to use marketing data that is scientific design component at schematic design step for successful interior design that can improve result. Hereupon, this study is doing to big dimension that utilizes 6sigma and makes standard process of only Interior Design, and did to dimension that present study phase verifies if '6sigma' is practical use possibility by intoner design process. Did by method that verification method of 6sigma practical use possibility analyzes "Information transmission efficiency improvement of department store display space" 6sigma project example. When see that example project is analyzed on Improvement constituent that "Design improvement" out of Vital few Xs of statistical analysis item must heighten the customers satisfaction rate conclusively, target process might be established because design becomes center of gravity if did design improvement very first time. Finally, possibility that 6sigma can utilize in process of interior design is verified, and it is scientific methodology that can utilize to all business members that there are not any special category of business even if is in practical use. Such scientific 6sigma method need persistent study that make standard process analyzing a lot of problems that is expected to be beaconed and happens substantially in here after to management development of interior design.