• Journal of the Korean Ceramic Society
• /
• v.35 no.1
• /
• pp.11-16
• /
• 1998

$VO_2$ thin films have been prepared on borosilicate glass substrate using alkoxide method to characterize the effects of fabricating factors on thermochromic performance. The gel films formed by spin coating were converted to $V_2O_5$ phase during oxidizing heat-tratment and the $VO_2$ phase were formed by reducing heat-treatement. The thermochromic switching properties of $VO_2$ thin films are strongly affected by the crystal phase and microstructure and those could be controlled by reducing heat-treatment conditions. The ther-mochromic switching characteristics of $VO_2$ thin films synthesized were measured at IR (2.5$\mu\textrm{m}$) as the transition temperature of $63^{\circ}C$ the transition width of $3.6^{\circ}C$and the maximum and minimum transmittance of 84% and 14% respectively.

• Journal of computational fluids engineering
• /
• v.12 no.4
• /
• pp.44-53
• /
• 2007

A three-dimensional (3D) unstructured hydrodynamic solver for transient two-phase flows has been developed for a 3D component of a nuclear system code and a component-scale analysis tool. A two-fluid three-field model is used for the two-phase flows. The three fields represent a continuous liquid, an entrained liquid, and a vapour field. An unstructured grid is adopted for realistic simulations of the flows in a complicated geometry. The semi-implicit ICE (Implicit Continuous-fluid Eulerian) numerical scheme has been applied to the unstructured non-staggered grid. This paper presents the numerical method and the preliminary results of the calculations. The results show that the modified numerical scheme is robust and predicts the phase change and the flow transitions due to boiling and flashing very well.

• Journal of Advanced Marine Engineering and Technology
• /
• v.29 no.4
• /
• pp.377-383
• /
• 2005

This paper deals with the flow characteristics of air-water two-phase flow in a vertical tube of 10mm I.D. and 600mm in length at an adiabatic condition. The obtained experimental data were covered with the liquid superficial velocity ranging from 0.095m/s to 2.56m/s. and the gas superficial velocity ranging from 0.032m/s to 21.08m/s. The effects of the gas and liquid superficial velocity on the flow pattern transitions, frictional pressure drop, and film thickness and gas-liquid interface roughness were also examined. It was found that the film thickness increased and the liquid film wave length was more longer with the liquid superficial velocity $j_L$ increasing at $j_G$ constant. It was also showed that the frictional pressure drops were experienced in three regions. namely increasing region(bubbly flow), decreasing region (Taylor bubble and slug flows) and re-increasing region (annular flow).

• Mass Spectrometry Letters
• /
• v.11 no.4
• /
• pp.65-70
• /
• 2020

Despite its great success in the field of proteomics, mass spectrometry has limited use for determining structural details of peptides, proteins, and their assemblies. Emerging ion mobility spectrometry-mass spectrometry has enabled us to explore the conformational space of protein ions in the gas phase, and further combinations with the gas-phase ion spectroscopy and the collision-induced unfolding have extended its abilities to elucidating the secondary structure and local details of conformational transitions. This review will provide a brief introduction to the combined approaches of IMS-MS with gas-phase ion infrared spectroscopy or collision-induced unfolding and their most recent results that successfully revealed higher-order structural details.

• Journal of Ceramic Processing Research
• /
• v.21 no.3
• /
• pp.319-325
• /
• 2020

Thermoelectric and transport properties of FeVSb1-xSnx (0.015<x<0.055) alloys were studied with respect to types of vials(zirconia and stainless steel), Sn contents and temperature. The results were compared with the previously studied samples synthesized by using stainless-vial. All the designated compositions in current work were prepared via a mechanical alloying process using a zirconia vial. Vacuum hot pressing was conducted to consolidate the mechanically alloyed powders. F43m symmetry was being confirmed from the Rietveld refinement pattern. The phase transitions during the milling process and vacuum hot processing were investigated and the results exhibited near single half-Heusler phases with a minor portion of the second phase within the matrix. The Second phase might play a role to reduce thermal conductivity. Electrical conductivity exhibited semi-metallic behavior in all the temperature range. Carrier concentrations are found to be decreased with the increasing Sn contents and the FeVSb0.955Sn0.045 specimen showed the ZTmax of 0.23 at 757 K.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.30 no.2
• /
• pp.86-90
• /
• 2017

This work reports the phase-change behavior and thermal stability of doped GeSbTe/GeSbTe bilayers. We prepared the bilayers using RF sputtering, and annealed them at annealing temperature ranging from $100^{\circ}C$ to $400^{\circ}C$. The sheet resistance of the bilayer decreased and saturated with increasing annealing temperature, and the saturated value was close to that of pure GeSbTe film. The surface of the bilayer roughened at $400^{\circ}C$, which corresponds to the surface roughening of doped GeSbTe film. Mixed phases of face-centered cubic and hexagonal close-packed crystalline structures were identified in the bilayers annealed at elevated temperature. These results indicate that the phase-change behavior of the bilayer depends on the concurrent phase-transitions of the two GeSbTe-based films. The dopants in the doped GeSbTe film were diffused out at annealing temperatures of $300^{\circ}C$ or higher, which implies that the thermal stability of the bilayer should be considered for its application in phase-change electronic devices.

• Bulletin of the Korean Mathematical Society
• /
• v.43 no.2
• /
• pp.277-292
• /
• 2006

We consider a single-server queue with service time distribution of phase type where positive customers, negative customers and disasters arrive according to a Markovian arrival process with marked transitions (MMAP). We derive simple formulae for the stationary queue length distributions. The Laplace-Stieltjes transforms (LST's) of the sojourn time distributions under the combinations of removal policies and service disciplines are also obtained by using the absorption time distribution of a Markov chain.

• Proceedings of the KIEE Conference
• /
• 2008.07a
• /
• pp.1266-1267
• /
• 2008

Liquid crystalline polymer BB-3(1-methyl) takes two kinds of glass phases which are liquid crystalline glass and liquid glass below the glass temperature. This study is aimed to analyze the phase transitions of those samples with variation of temperature. For the analyzing temperature dispersion of dielectric constants was measured and the results were analyzed.

• 한국초전도학회:학술대회논문집
• /
• v.11
• /
• pp.2-2
• /
• 2001

• Proceedings of the Materials Research Society of Korea Conference
• /
• 1997.10a
• /
• pp.133-133
• /
• 1997