• Journal of the Korean Magnetics Society
• /
• v.15 no.3
• /
• pp.172-176
• /
• 2005

Four nano-sized Fe-nano particle samples synthesized by Chemical Vapor Condensation (CVC) were analyzed using $M\ddot{o}ssbauer$ spectroscopy, XRD, BET and TEM. The samples were consisted as functions of carrier gas and decomposition temperature. The synthesized nanoparticles consisted of two- or three-layers with the circular shape. The average particle size was increased with increasing the decomposition temperature. At $500^{\circ}C$ for the decomposition temperature, $Fe_3C$ was formed more under the environment of CO carrier gas than that of $CH_4$. However, at $1,100^{\circ}C$, almost of Fe-nano particles were transformed into $Fe_3C$ with using both carrier gas.

• Journal of Environmental Science International
• /
• v.12 no.3
• /
• pp.265-274
• /
• 2003

The Pasquill-Gifford stability category is a very important scheme of the Gaussian type dispersion model defined the complex turbulence state of the atmosphere by A grade(very unstable) to F grade(very stable). But there has been made a point out that this stability category might decrease the predictability of the model because it was each covers a broad range of stability conditions, and that they were very site specific. The APSM (Air Pollution Simulation Model) was composed of the turbulent parameters, i.e. friction velocity(${\mu}$$\_$*/), convective velocity scale($\omega$$\_$*/) and Monin-Obukhov length scale(Ｌ) for the purpose of the performance increasing on the case of the unstable atmospheric conditions. And the PDF (Probability Density Function)model was used to express the vertical dispersion characteristics and the profile method was used to calculate the turbulent characteristics. And the performance assessment was validated between APSM and EPA regulatory models(TEM, ISCST), tracer experiment results. There were very good performance results simulated by APSM than that of TEM, ISCST in the short distance (<1415 m) from the source, but increase the simulation error(%) to stand off the source in others. And there were differences in comparison with the lateral dispersion coefficient($\sigma$$\_$y/) which was represent the horizontal dispersion characteristics of a air pollutant in the atmosphere. So the different calculation method of $\sigma$$\_$y/ which was extrapolated from a different tracer experiment data might decrease the simulation performance capability. In conclusion, the air pollution simulation model showed a good capability of predict the air pollution which was composed of the turbulent parameters compared with the results of TEM and ISCST for the unstable atmospheric conditions.

• Journal of the Korean Electrochemical Society
• /
• v.14 no.3
• /
• pp.157-162
• /
• 2011

The stability at elevated temperatures of a surface film formed on a graphite electrode in lithium secondary batteries was investigated by transmission electron microscopy (TEM) and electrochemical AC impedance spectroscopy (EIS). TEM analysis revealed that the surface film partly dissolved in the electrolyte solution during storage at $60^{\circ}C$, resulting in a decrease in the thickness of the surface film and a change in its morphology to a porous structure. On the other hand, an increase in the impedance of the surface film which is attributable to a change in composition of the surface film was confirmed by EIS analysis during the storage at $60^{\circ}C$. It was also shown that the addition of vinylene carbonate or 1,3-propane sultone or etylene sulfite, even if limited, improves the stability of the surface film at elevated temperatures.

• Journal of Korean Society of Steel Construction
• /
• v.9 no.4 s.33
• /
• pp.515-521
• /
• 1997

The effects of heat treatment and fiber orientation on tensile strength and fatigue behavior were studied in a continuously reinforced. magnesium-based composite Following an earlier TEM investigation, specimens were thermally aged to modified the interfacial zone between the alumina fibers and the magnesium alloy matrix. From the tensile experimental results, the ultimate tensile strength of the aged specimens were lower than that of the as-fabricated due to weak fiber-matrix interfacial strength with chemical reaction during the thermal processing. The fatigue crack growth experiments were conducted with specimens having the fiber orientation normal to the crack growth direction (longitudinal) and also specimens with the fibers oriented parallel to the crack growth direction(transverse). A comparison of the fatigue crack growth behavior indicates that aged longitudinal specimens are more resistant to fatigue crack growth the as-fabricated longitudinal specimens. Conversely, as-fabricated transverse specimens are more resistant to fatigue crack growth than aged transverse specimens.

• Korean Journal of Food Science and Technology
• /
• v.45 no.3
• /
• pp.370-375
• /
• 2013

Propolis is a resinous mixture found in the tree buds, sap flows, and other botanical sources, which is used by honey bees in the construction of their hives. Antimicrobial effects of propolis were evaluated against Streptococcus mutans KCTC 3065, S. sobrinus KCTC 3308, S. sobrinus KCTC 5134, and Porphyromonas gingivalis KCTC 5352 by an agar diffusion assay. Sensitivity of these microorganisms to propolis was evaluated in broth containing different concentrations of propolis at $37^{\circ}C$, followed by observation using transmission electron microscopy (TEM). Propolis inhibited all oral microorganisms tested at the minimum inhibitory concentration (MIC) of $0.14mg/{\mu}L$ in the agar diffusion assay. Treatment with 0.06 and $0.22mg/{\mu}L$ of propolis had a bactericidal effect in a concentration- and treatment time-dependent manner against the tested microorganisms. TEM of propolis-treated S. mutans KCTC 3065 and P. gingivalis KCTC 5352 revealed structural damage of the cell membrane. The activity of propolis was affected by heat and pH treatment. The results indicate that propolis shows antibacterial activity against oral microorganisms and that it has potential for future applications in the food industry.

• Journal of Animal Science and Technology
• /
• v.48 no.2
• /
• pp.191-202
• /
• 2006

In addition to the removal of dying or dead lutein cells by phagocytosis in many species, macrophages exert both luteotropic effect during maturation period and luteolytic effect during degenerative period via mediating autocrine/paracrine actions of self-producing cytokines in the corpus luteum. In this experiment, immunohistochemical and transmission electron microscopic (TEM) studies were performed to observe the morphologic changes of luteal macrophages during luteolysis. A small number of macrophages and low immunoreactivity were present at the mature stage. The number of macrophages and immunoreactivity gradually increased along the advance of luteolysis. Two subtypes of macrophages could be observed through TEM observation. One type of macrophage located between the large lutein cells contained no lipid droplets in their cytoplasm at mature stage. The other type of macrophage located near the blood vessels contained many lipid droplets in their cytoplasm during luteolysis. Particularly, no phagocytic macrophages were observed, which suggested the macrophages in the porcine corpus luteum did not involve in the phagocytotic elimination of dying lutein cells.

• Korean Journal of Materials Research
• /
• v.17 no.4
• /
• pp.207-214
• /
• 2007

We fabricated thermally-evaporated 10 -Ni/(poly)Si and 10 -Ni/1 -Ir/(poly)Si structures to investigate the microstructure of nickel monosilicide at the elevated temperatures required for annealing. Silicides underwent rapid at the temperatures of 300-1200 for 40 seconds. Silicides suitable for the salicide process formed on top of both the single crystal silicon actives and the polycrystalline silicon gates. A four-point tester was used to investigate the sheet resistances. A transmission electron microscope(TEM) and an Auger depth profile scope were employed for the determination of vertical section structure and thickness. Nickel silicides with iridium on single crystal silicon actives and polycrystalline silicon gates shoed low resistance up to 1000 and 800, respectively, while the conventional nickle monosilicide showed low resistance below 700. Through TEM analysis, we confirmed that a uniform, 20 -thick silicide layer formed on the single-crystal silicon substrate for the Ir-inserted case while a non-uniform, agglomerated layer was observed for the conventional nickel silicide. On the polycrystalline silicon substrate, we confirmed that the conventional nickel silicide showed a unique silicon-silicide mixing at the high silicidation temperature of 1000. Auger depth profile analysis also supports the presence of thismixed microstructure. Our result implies that our newly proposed iridium-added NiSi process may widen the thermal process window for the salicide process and be suitable for nano-thick silicides.

• Journal of Ocean Engineering and Technology
• /
• v.13 no.2 s.32
• /
• pp.108-115
• /
• 1999

To study measurement of coated steel corrosion in mortar, a transient electro-magnetic(TEM) method was adapted. The sensors were made of enamelled wire with diameter of 0.25mm(transmitter), 0.1mm(receiver) and the secondary electro motive force(EMF) was measured with SIROTEMIII. The sensors configuration was used as in loop configuration. After coated steels were corroded by the salt spray during 3, 7, 15, 25days, they were embedded in mortar which were made from sand : cement : water ratio of 2 : 1 :0.5. To investigate coated steel corrosion in mortar, the sensors were used. ( sensorl - $T_x$ : $4{\Omega}$, $R_x$ : $10{\Omega}$, $3{times}3cm$, sensor2 - $T_x$ : $8{\Omega}$, $R_x$ : $10{\Omega}$, $3{times}3cm$, sensor3 - $T_x$ : $4{\Omega}$, $R_x$ : $10{\Omega}$, $6{times}6cm$, sensor4 - $T_x$ : $8{\Omega}$, $R_x$ : $10{\Omega}$, $6{times}6cm$). The obtained results showed that the secondary EMF was decreased with specimens of 3, 7days corroded coationg steel in mortar and then increased with specccimens of 15, 25days corroded one. And it was confirmed that measurement of coated steel corrosion in mortar by a transient electro-magnetic(TEM) method is possible.

• Journal of the Korean Ceramic Society
• /
• v.38 no.11
• /
• pp.1030-1036
• /
• 2001

Hydroxyapatite[COL] nanocomposite was prepared through coprecipitation process. The chemical bond formation between HAP and COL was confirmed by diffusive reflectance FT-IR and TEM observation. Higher concentration of COL in the preparation induced tiny nanocrystalline composite particles, but lower concentration of COL contributed to form the well developed HAP particles. From TEM observation and ED(Electron Diffraction) pattern the embedded HAP nanoparticles were oriented along the c-axis of COL fiber. In an aqueous system of constant [Ca$\^$2+/] and [PO$_4$$\^$3-/], quantity of soluble COL matrix was doing an important role of controlling the heterogeneous nucleation site for the formation of HAP nanocrystals. Higher concentration of COL will provide more nucleation sites for Ca$\^$2+/ and so the concentration of calcium ions for the total number of active nucleation sites will be getting relatively dilute.

• Journal of the Mineralogical Society of Korea
• /
• v.17 no.4
• /
• pp.327-338
• /
• 2004

XRD studies on annealed Na-feldspar (Amelia albite) at $1100^{\circ}C$ showed rapid structural changes due to Si-Al disordering, which resulted in phase transformations from low albite to high albite by 4-days annealing test. TEM SAED analyses on the annealed samples revealed a trend of structural changes, but estimation of the structural state was difficult due to a large deviation of the SAED data. Optimum conditions of CBED analyses on albite was established by employing a cooling specimen holder, 120 kV of acceleration voltage, 37 Jim of condenser aperture size and 25 nm of spot size. A proper orientation showing distinct changes of HOLZ lines corresponding to the structure changes of albite turned out to be close to the [418] direction with $-1.2^{\circ}$ tilting, where the width of two HOLZ lines in low albite was opposite to those in high albite.