• Journal of Photoscience
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• v.11 no.1
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• pp.35-40
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• 2004

[Ru(2,2'-bipyridine)$_2$(4,4'-dicarboxy-2,2'-bipyridine)]$^{2+}$(RuBDc) is a very photostable probe that possesses favorable photophysical properties including long lifetime, high quantum yield, large Stokes' shift, and highly polarized emission. To evaluate the usefulness of this luminophore (RuBDc) for studying macromolecular dynamics, its intensity and anisotropy decays when conjugated to RNA bacteriophage MS2 were examined using frequency-domain fluorometry with a high-intensity, blue light-emitting diode (LED) as the modulated light source. The intensity decays were best fit by a sum of two exponentials, and the mean intensity decay time was 442.2 ns. The anisotropy decay data showed a single rotational correlation time (2334.9 ns), which is typical for a spherical molecule. The use of RuBDc enabled us to measure the rotational correlation time up to several microseconds. These results indicate that RuBDc can be useful for studying rotational diffusion of biological macromolecules.s.

• Journal of Welding and Joining
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• v.35 no.3
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• pp.52-61
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• 2017

Transient liquid phase (TLP) bonding is essential technology to repair micro-cracking on the airfoil of blades and vanes for gas turbines. Understanding of the characteristics of TLP bonding of the superalloys is necessary in the application of the technology for repairing these components. In this study, the focus was on investigating TLP bonding characteristics of ${\gamma}^{\prime}$ precipitation strengthened Ni based superalloy. TLP bonding was carried out with an amorphous filler metal in various bonding conditions, and the microstructural characterization was investigated through optical microscopy (OM) and electron probe micro-analysis (EPMA). The experimantal results explained clearly that bonding temperatures had critical effects on the TLP bonding behaviors, and that isothermal solidication of the joints made at higher temperatures than $1170^{\circ}C$ was controlled by Ti diffusion instead of B.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.3
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• pp.426-431
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• 1996

It is well known that the understanding of the complex mechanism of magnetoplasma is closely related with understanding of the collective behavior of discharge plasma parameters such as the cathode-sheath potential, cathode-sheath thickness, electron temperature, electron density, and ambipolar diffusion. In this paper, some of the relationships between these plasma parameters and magnetic field is investigated experimentally with a Langmuir probe in the magnetoplasma generated by D.C diode system. It is found that when magnetic field is increased, cathode-sheath potential, cathode-sheath thickness, and ambipolar diffusion are decreased. In addition, peak ion density obtained as a parameter of ionic signal voltage by Faraday cup method is independent of magnetic field. (author). 9 refs., 11 figs.,1 tab.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.208-208
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• 1999

It is found that with increasing power, the measured electron energy distribution by Langmuir probe evolves into a Druyvesteyn-like electron energy distribution in the low-pressure regime of 1mTorr in a small inductively coupled plasma. Electron bounce resonance is introduced to explain the transition of the electron energy distribution against the rf power, The energy diffusion coefficients which determine the shape of the electron energy distribution in elastic range are calculated with and without electron bounce resonance. This electron energy distribution transition is well explained by the electron bounce resonance.

• Journal of the Korean Magnetic Resonance Society
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• v.9 no.1
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• pp.29-37
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• 2005

Intra-cellular drug uptake in Xenopus laevis oocyte has been elucidated using localized MR spectroscopy (MRS) and PFG NMR techniques at a 600 $MH_z$(Bruker, 14.1 T) NMR spectrometer. The localized MRS has been done with a homemade probe, and shows the intra-cellular uptake of nicotinamide. The self-diffusion of the molecule in Xenopus oocyte was obtained by PFG NMR technique. The measured data are well fitted with a linear combination of two exponential functions, which shows that there are two types of drug molecules, intra-and extra-cellular molecules. Diffusion coefficients of intra- and extra-cellular drug molecules are 3.7 $\times$ $10^{-11}$ $\m^{2}/s$and 6.4 $\times$ $10^{-10}$ $\m^{2}/s$, respectively. In the weighting factors there is shown that about 5% of drug molecule is inside the cells. These techniques can be used for drug screening in molecule-, cell-, and tissue-based preclinical test.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.10
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• pp.828-834
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• 2001

Zinc oxide (ZnO) films deposited on indium (In) films were post-annealed in a rapid thermal anealing (RTA) system. The ZnO/In films were RTA-treated in air or a vacuum ambient. The crystallographic properties and surface morphologies of the films were studied before and after the RTA by X-ray diffraction(XRD) and scanning electron microscopy (SEM), respectively. The resistivity variation of the films with RTA temperature and time was measured by the 4-point probe method. Auger electron spectroscopy (AES) was carried out to figure out the redistribution of indium atoms in the ZnO films. The resistivity of the ZnO/In films decreased to 2$\times$10$\^$-3/ Ωcm by diffusion of the In. The In diffusion into the ZnO films roughened the surface of ZnO films. The results of depth profile by AES showed a hump of In atoms around ZnO/In interface after the RTA at 800 $\^{C}$. The effects of temperature time and ambient during the RTA on the structural and electrical properties of the ZnO/In films were discussed.

• Korean Journal of Materials Research
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• v.13 no.7
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• pp.460-464
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• 2003

Ni and Ti films were deposited by the thermal evaporator, and then annealed in the N$_2$ ambient at 300-80$0^{\circ}C$ in a RTA(rapid thermal annealing) system. Four point probe, AEM, FESEM, AES, and XPS were used to study the effects of Ti-capping layers on the thermal stability of NiSi thin films. The Ti-capped NiSi was stable up to $700^{\circ}C$ for 100 sec. RTA, while the uncapped NiSi layers showed high sheet resistance after $600^{\circ}C$. These results were due to that the Ni in-diffusion and Si out-diffusion were retarded by the capping layer, resulting in the suppression of the formation of NiSi$_2$and Si grains at the surface.

• Korean Journal of Materials Research
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• v.24 no.7
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• pp.363-369
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• 2014

This is the study on diffusion of ceramic body oxide compounds to glaze. For ceramic bodies, no ferrous oxides contain white ware, celadon, and 3 wt% iron oxides contained white ware was used in this experiment. These ceramic bodies were glazed by transparency glaze, iron oxides contained glaze, and glaze made by pine tree ash that treated in 1240 degree, under reduction condition for an hour. An electron probe microanalyzer(EPMA) was used to study diffusion of oxides and to calculate distance of ceramics bodies. As a result, only iron oxide and magnesium oxide from the body diffused to glaze, and also made a band which shown very thin layer of iron oxide and magnesium oxide between the body and glaze. The densest band of iron oxide formed 100 to $150{\mu}m$ in the glaze, and the densest band of magnesium oxide was found 50 to $100{\mu}m$ in the glaze. Therefore, it could be concluded that iron oxide in the body is diffused to the glaze and it affects the color of glaze, even though iron oxide exists in the glaze. Furthermore, the thickness of the glaze has an effect on the color of celadon.

• Journal of the Korean Vacuum Society
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• v.10 no.1
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• pp.112-118
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• 2001

Magnetic field is commonly used in low temperature processing plasmas to enhance the performance of the plasma reactors. E$\times$B magnetron or surface multipole configuration is the most popular. However, the properties of capacitively coupled rf plasma confined by axial static magnetic field have rarely been studied. With these background, the effect of magnetic field on the characteristics of capacitively coupled 13.56 MHz/40 KHz argon plasma was studied, Ion saturation current, electron temperature and plasma potential were measured by Langmuir probe and emissive probe. At low pressure region (~10 mTorr), ion current increases by a factor of 3-4 due to reduction of diffusion loss of charged particles to the wall. Electron temperature slightly increases with magnetic field for 13.56 MHz discharge. However, for 40 KHz discharge, electron temperature decreased from 1.8 eV to 0.8 eV with magnetic field. It was observed that the magnetic field induces large temporal variation of the plasma potential. Particle in cell simulation was performed to examine the behaviors of the space potential. Experimental and simulation results agreed qualitatively.

• 한국초전도학회:학술대회논문집
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• v.9
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• pp.189-195
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• 1999

We have studied the vortex dynamics in YBa$_2Cu_3O_7$ single crystals with columnar defects using micro Hall-probe array. The Hall-probe array technique allowed a simultaneous measurement of the time and spatial dependence of the vortex density so that more detailed information on flux dynamics could be obtained. We found that field profiles inside sample were similar to the Bean's critical state model from the magnetic hysteresis measurement. Normalized relaxation rates were maximum near the center and decreased toward the edge if applied field H$_{app}$ is greater than the penetration field H. But applied magnetic field H$_{app}$ is less than H, relaxation rates were minimum near the center and increased toward edge. We found that glassy exponent ${\mu}$ has the value of ${\sim}$ 1 whose corresponding vortex motion is half-loop excitation. However, single vortex creep, ${\mu}$ ${\sim}$ 1/7, was also found at 30 K and H$_{app}$ ${\cong}$ H'. Calculation of activation energy, U, was possible from direct analysis of the local relaxation data using the basic diffusion equation. From these results, we found that U increases logarithmically with time and U around center was lower than that at the edge.