• Transactions of the Korean Society of Mechanical Engineers
• /
• v.14 no.3
• /
• pp.702-715
• /
• 1990

This paper describes behaviors of two-phase open channel flow inside the flash chamber of a horizontal Multi-Stage-Flash evaporator numerically along with the experimental observations. Bubble trajectories and the velocity and temperature distributions of the liquid phase were predicted by using the particle-source-in-cell(PSI-Cell) method with the appropriate bubble motion/growth equations. Size and number of bubble nuclei embedded in the incoming liquid(brine) were taken into account as important parameters in addition to the conventional ones such as the velocity, degree of inlet superheat, inlet opening height, and the liquid level. Bubble motions, which are unsteady, appeared to be mostly determined by the buoyancy and the drag forces. The calculations, though a number of simplifying assumptions were made, reasonably simulated the hydrodynamic behaviors of the two-phase horizontal stream observed in the experiments. The simulated temperature distributions also agreed fairly well with the other's measurements. Non-equilibrium allownaces, evaluated from the simulated temperature distributions, were within the range of those obtained from the existing correlations, and reduced with the increases of the number and size of incoming bubble nuclei due to vigorous flashing.

• Fire Science and Engineering
• /
• v.24 no.4
• /
• pp.41-46
• /
• 2010

High strength concrete (HSC) has been mainly used in large SOC structures. HSC have superior property as well as improvement in durability compared with normal strength concrete. In spite of durability of HSC, explosive spalling in concrete front surface near the source of fire occurs serious problem in structural safety. Therefore, this study is concerned with experimentally investigation of fire resistance at high temperature due to fireproof material covering thickness in addition to concrete cover. From the test result, it was appeared that the use of fireproof material results in good performance for fire resistance and spalling prevention, and the optimal fireproof covering thickness is 1~3mm. On the other hand, the temperature was rapidly increased by explosive spalling within 30 minutes and showed very little rise caused by evaporation heat after then. It was also found that the void channel was remained at high temperature as PP fiber melts at about $200^{\circ}C$, and the pore pressure in concrete was decreased.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.5 no.1
• /
• pp.25-36
• /
• 1995

We have investigated the structure and the conductivity of the $Cd_{1-y}Zn_{y}$ Te films evaporated on the glass substrates (Corning 7059) by Electron Beam Evaporator (EBE) in pressure of approximately $1 {\times} 10^{-6}$ torr.The structure temperatures were held at both room temperature and $300^{\circ}C$, and the samples have annealed for an hour at $300^{\circ}C$ The survace com-position of the as-prepared films were slightly different from those of CdZn Te source material.Cd losses on the CdZnTe surface was measured about 4% of atomic ratio at room temperature substrate, whereas Zn atomic ratio was nearly constant, relatively. The strure is observed to be polycrystalline whose phase is mainly cubic phase. Thermal expansion coefficient was $6.30 {\times} 10^{-5}/^{\circ}C$ which was calculated from the variation of lattice parameter by X-ray powder pat-terns measured at $400^{\circ}C$.Diffraction peaks were slightly increased by annealing for an hour at $300^{\circ}C $, but they werey highly affected by substrate temperature during evaporation.

• Bulletin of the Korean Chemical Society
• /
• v.33 no.4
• /
• pp.1135-1140
• /
• 2012

An electrochromatographic microchip with carboxyl-group-derivatized mono-disperse silica packing was prepared from the corresponding colloidal silica solution by utilizing capillary action and self-assembly behavior. The silica beads in water were primed by the capillary action toward the ends of cross-patterned microchannel on a cyclic olefinic copolymer (COC) substrate. Slow evaporation of water at the front of packing promoted the self-assembled packing of the beads. After thermally binding a cover plate on the chip substrate, reservoirs for sample solutions were fabricated at the ends of the microchannel. The packing at the entrances of the microchannel was silver coated to fix utilizing an electroless silver-plating technique to prevent the erosion of the packed structure caused by the sudden switching of a high voltage DC power source. The electrochromatographic behavior of the microchip was explored and compared to that of the microchip with bare silica packing in basic borate buffer. Electrophoretic migration of Rhodamine B was dominant in the microchip with the carboxyl-derivatized silica packing that resulted in a migration approximated twice as fast, while the reversible adsorption was dominant in the bare silica-packed microchip. Not only the faster migration rates of the negatively charged FITC-derivatives of amino acids but also the different migration due to the charge interaction at the packing surface were observed. The electrochromatographic characteristics were studied in detail and compared with those of the bare silica packed microchip in terms of the packing material, the separation potential, pH of the running buffer, and also the separation channel length.

• Preventive Nutrition and Food Science
• /
• v.10 no.2
• /
• pp.111-117
• /
• 2005

Radical scavenging activity of water and methanol extracts of mulberry juice and cake prepared from mulberry fruit (Morus spp.) was evaluated using three in vitro assay systems. Mulberry fruits were homogenized with $0.5\%$ trifluoroacetic acid (TFA) in distilled water, filtered with cheeze-cloth and centrifuged to yield mulberry juice and cake. Mulberry juice was evaporated and solubilized in $0.5\%$ TFA in distilled water or $0.5\%$ TFA in $80\%$ aqueous methanol, followed by filtration and evaporation to obtain water (WMJ) and methanol (MMJ) extracts of mulberry juice. Mulberrry cake also was extracted with the above same solvents, and thereby finally obtaining water (WMC) and methanol (MMC) extracts of mulberry cake. Among four extracts, the MMC showed the most potent radical scavenging activity against DPPH radical $(IC_{50}=167.45\;{\mu}g/mL)$, and superoxide $(IC_{50}=36.18\;{\mu}g/mL)$ and hydroxyl radicals $(IC_{50}=467.08\;{\mu}g/mL)$. The WMC also exhibited stronger radical scavenging activity than those of two other mulberry juice extract, WMJ and MMJ. Meanwhile, the MMJ exerted stronger three radical scavenging activity than the WMJ. Total phenolic content of the water and MeOH extracts from mulberry cake was higher than that of the water and MeOH extracts from mulberry juice. Thus, these results suggest that the extracts of mulberry cake with high dietary phenolics may be useful potential source of natural antioxidant as radical scavenger.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2001.11a
• /
• pp.35-35
• /
• 2001

agnesium Oxide (MgO) with a NaCI structure is well known to exhibit high secondary electron emission, excellent high temperature chemical stability, high thermal conductance and electrical insulating properties. For these reason MgO films have been widely used for a buffer layer of high $T_c$ superconducting and a protective layer for AC-plasma display panels to improve discharge characteristics and panel lifetime. Up to now MgO films have been synthesized by lE-beam evaporation, Molecular Beam Epitaxy (MBE) and Metalorganic Chemical Vapor Deposition (MOCVD), however there have been some limitations such as low film density and micro-cracks in films. Therefore magnetron sputtering process were emerged as predominant method to synthesis high density MgO films. In previous works, we designed and manufactured unbalanced magnetron source with high power density for the deposition of high quality MgO films. The magnetron discharges were sustained at the pressure of O.lmtorr with power density of $110W/\textrm{cm}^2$ and the maximum deposition rate was measured at $2.8\mu\textrm{m}/min$ for Cu films. In this study, the syntheses of MgO films were carried out by unbalanced magnetron sputtering with various $O_2$ partial pressure and specially target power densities, duty cycles and frequency using pulsed DC power supply. And also we investigated the plasma states with various $O_2$ partial pressure and pulsed DC conditions by Optical Emission Spectroscopy (OES). In order to confirm the relationships between plasma states and film properties such as microstructure and secondary electron emission coefficient were analyzed by X-Ray Diffraction(XRD), Transmission Electron Microscopy(TEM) and ${\gamma}-Focused$ Ion Beam (${\gamma}-FIB$).

• Current Photovoltaic Research
• /
• v.3 no.1
• /
• pp.21-26
• /
• 2015

High efficiency $Cu(In,Ga)Se_2$ solar cells are generally prepared above $500^{\circ}C$. Lowering the process temperature can allow wider selection of substrate material and process window. In this paper, the three-stage co-evaporation process widely used to grow CIGS thin film at high temperature was modified to reduce the maximum substrate temperature. Below $400^{\circ}C$ the CIGS films show poor crystal growth and lower solar cell performance, in spite of external Na doping by NaF. As a new approach, Cu source instead of Cu with Se in the second stage was applied on the $(In,Ga)_2Se_3$ precursor at $400^{\circ}C$ and achieved a better crystal growth. The distribution of Ga in the films produce by new method were investigated and solar cells were fabricated using these films.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2006.06a
• /
• pp.467-468
• /
• 2006

We report on the fabrication of P3HT-based thin-film transistors (TFT) that consist of indium-zinc-oxide (IZO), PVP (poly-vinyl phenol), and Ni for the source-drain (S/D) electrode, gate dielectric, and gate electrode, respectively. The IZO S/D electrodes of which the work function is well matched to that of P3HT were deposited on a P3HT channel by thermal evaporation of IZO and showed a moderately low but still effective transmittance of ~25% in the visible range along with a good sheet resistance of ${\sim}60{\Omega}/{\square}$. The maximum saturation current of our P3HT-based TFT was about $15{\mu}A$ at a gate bias of -40V showing a high field effect mobility of $0.05cm^2/Vs$ in the dark, and the on/off current ratio of our TFT was about $5{\times}10^5$. It is concluded that jointly adopting IZO for the S/D electrode and PVP for gate dielectric realizes a high-quality P3HT-based TFT.

• Journal of Fisheries and Marine Sciences Education
• /
• v.16 no.2
• /
• pp.257-270
• /
• 2004

The two-phase closed thermosyphon is a heat transfer device capable of transfer large quantities of heat from a source to a sink by taking advantage of the high heat transfer rates associated with the evaporation and condensation of a working fluid within the device. A study was carried out with the performance of the heat transfer of the thermosyphon having 50, 60, 70, 80, 90 internal micro grooves in which boiling and condensation occur. A plain thermosyphon having the same inner and outer diameter as the grooved thermosyphon is also tested for comparison. Water, methanol and ethanol have been used as the working fluids. The liquid filling as the ratio of working fluid volume to total volume of thermosyphon, the inclination angle, micro grooves and operating temperature have been used as the experimental parameters. The heat flux and the boiling and the condensation heat transfer coefficient and overall heat transfer coefficient at the condenser and evaporator zone are estimated from the experimental results. The experimental results have been assessed and compared with existing correlations. Imura's and Kusuda's correlation for boiling showed in good agreement with experimental results within ${\pm}20$％ in plain thermosyphon. The maximum heat transfer rate was obtained when the liquid fill ratio was about 25%. The high heat transfer coefficient was found between 25o and 30o of inclination angle for water and between 20o and 25o for methanol and ethanol. The relatively high rates of heat transfer have been achieved in the thermosyphon with internal micro grooves. The micro grooved thermosyphon having 60 grooves shows the best heat transfer coefficient in both condensation and boiling. The maximum enhancement (i.e. the ratio of the heat transfer coefficients of the micro grooved thermosyphon to plain thermosyphon) is 2.5 for condensation and 2.3 for boiling.

• Korean Journal of Construction Engineering and Management
• /
• v.23 no.1
• /
• pp.73-82
• /
• 2022

Waste paint, one of the specified wastes in Korea, is currently treated entirely by incineration treatment method, and is hardly recycled compared to other wastes. Incineration treatment method also causes environmental problems such as air pollution. Thus, this study breaks away from the existing incineration treatment method of waste paint and switch to a method of pretreatment operation through evaporation, condensation, and thermal decomposition by temperature control. and then proposes a sustainable waste paint treatment process that can be recycled as an alternative energy heat source. If a new method of disposing of waste paint and technology for recycling are developed and disseminated, it is expected that the effect will be large from an economic and environmental point of view.