• Korean Chemical Engineering Research
• /
• v.44 no.6
• /
• pp.614-622
• /
• 2006

A Study on the characteristics of $Ta/Ta_2O_5/MnO_2$ capacitor applied $MnO_2$ by means of pyrolysis of manganese nitrate solution was carried out. Single phase of $MnO_2$ was obtained in the pyrolysis temperature range of 230 to $250^{\circ}C$ by TG/DSC analysis on manganese nitrate solution. Temperature of pyrolysis, concentration of manganese nitrate solution and the number of pyrolysis were selected for the basic parameters of embodying $MnO_2$ solid electrolyte and then the effects of these parameters on the characteristics of capacitor were estimated. The characteristics of capacitor pyrolyzed radiationally was superior to that of capacitor pyrolyzed convectionally on the basis of these optimized parameter conditions. It was verified that radiational pyrolysis formed smaller spherical $MnO_2$ particles than those of convectional one relatively and these facts resulted in forming uniform and dense solid electrolyte layer into the microporous sintered body of capacitor.

• Journal of the Mineralogical Society of Korea
• /
• v.32 no.2
• /
• pp.103-111
• /
• 2019

In this study, characteristics of sediments and suspended solids flowing into Andong and Imha Dam was analyzed by color, X-ray diffraction and ICP/MS analysis. The minerals of sediments and suspended solid consist mainly of quartz, albite, chlorite, illite and small amounts of montmorillonite and kaolinite. Unlike the Andong Dam, the Imha Dam sediments contain large amounts of calcite. Color of sediments and suspended solids varies from grayish brown to dark orange. The concentrations of major heavy metals of sediments and suspended solids in the Andong and the Imha Dam are higher than the US National Oceanic and Atmospheric Administration standard values. The concentration of heavy metals in sediments of Andong is higher than that of Imha Dam because concentration of heavy metals in the suspended solid flowing into Andong is higher than that of Imha Dam.

• Journal of the Korean Ceramic Society
• /
• v.43 no.12 s.295
• /
• pp.812-822
• /
• 2006

This study amis to investigate the functional analysis of anode and cathode materials in Anode supported Solid Oxide Fuel Cell. The concentration polarization of single cell was investigated with CFD (Computational Fluid Dynamics) method for the case of the different morphology by using four types of unit cell and discussed to reduce the concentration polarization. The concentration polarization at anode side effected the voltage loss in Anode supported Solid Oxide Fuel Cell and increased contact areas between fuel gas and anode side could reduce the concentration polarization. For intermediate temperature operation, Anode-supported single cells with thin electrolyte layer of YSZ (Yttria-Stabilized Zirconia) were fabricated and short stacks were built and evaluated. We also developed diesel and methane autothermal reforming (ATR) reactors in order to provide fuels to SOFC stacks. Influences of the $H_2O/C$ (steam to carbon ratio), $O_2/C$ (oxygen to carbon ratio) and GHSV (Gas Hourly Space Velocity) on performances of stacks have been investigated. Performance of the stack operated with a diesel reformer was lower than with using hydrogen as a fuel due to lower Nernst voltage and carbon formation at anode side. The stack operated with a natural gas reformer showed similar performances as with using hydrogen. Effects of various reformer parameters such as $H_2O/C$ and $O_2/C$ were carefully investigated. It is found that $O_2/C$ is a sensitive parameter to control stack performance.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.11 no.2 s.23
• /
• pp.109-115
• /
• 2005

Hydrocyclone has been widely used for the solid-liquid separation in many industrial sites because of its comparatively preferable applications that can be applied to wide-range particle sizes. If seawater with impurities flows through pumps or heat exchanger, it might cause an decrease in the efficiency of cooling system In this paper, we have suggested some methods of separating impurities from seawater in the cooling system by using a Hydrocyclone. The effects of design factors as solid concentration, cyclone inlet pressure, flow rate and diameter of underflow on the separating performance of the Hydrocyclone were investigated The results from this study are summarized as follows: 1) In proportion to the decrease of solid concentration, the efficiency of solid-liquid separation is improved. 2) According as the cyclone inlet pressure increases the efficiency of separation is improved. Conclusively, this research suggested that the Hydrocyclone will be used as a pre-treatment system of cooling water in machines, and eventually prevent unexpected accidents in engine systems.

• Proceedings of KOSOMES biannual meeting
• /
• 2004.11a
• /
• pp.109-115
• /
• 2004

Hydrocyclone has been widely used for the solid-liquid separation in many industrial sites because of its comparatively preferable applications that can be applied to wide-range particle sizes. If seawater with impurities flows through pumps or heat exchanger, it might cause an decrease in efficiency of cooling system. In this paper, we have suggested some methods of separating impurities from seawater in the cooling system by using a Hydrocyclone. The effects of design factors as solid concentration, cyclone inlet pressure, flow rate and diameter of underflow on the separating performance of the Hydrocyclone were investigated The results from this study are summarized as follows: 1) In proportion to the decrease of solid concentration, the efficiency of solid-liquid separation is improved 2) According as the cyclone inlet pressure increases the efficiency of separation is improved Conclusively, this research suggested that the Hydrocyclone will be used as a pre-treatment system of cooling water in machines, and eventually prevent unexpected accidents in engine systems.

• Journal of the Korean GEO-environmental Society
• /
• v.15 no.12
• /
• pp.109-115
• /
• 2014

The purpose of this study is to estimate the sediment volume concentration of the liquified-solid mixture which is included fine sediment fractions, according to the variance of the channel slope and the water supply. The numerical model was performed by using the Finite Differential Element Method (FDM) based on the equation for the mass conservation, momentum conservation and the equation of coarse sediment an fine sediment. In comparison of varying the channel slope, the deeper the channel slope, the inflection point of the sediment concentration was occurred rapidly. In comparison of variance of the water supply, as the water supply increases fluctuation with high sediment concentration. In this situation, debris flow changes to the turbulent flow and the sediment becomes to be floated. In comparison varying the length paved saturated sediment, the longer the length, the high concentration of sediment occurred, for the safety of the slope it is needed to check the possibility of the erosion in the slope by debris flow. The results of this study will provide useful information in predicting of the disaster by the liquified-solid mixture and in prevention of the debris flow with various the slope in the mountain side.

• Journal of the Korean Electrochemical Society
• /
• v.3 no.4
• /
• pp.204-210
• /
• 2000

The control of dissolved aluminum concentration in the hot dip zinc galvanizing bath is greatly important in producing galvannealed steel sheets. The purpose of present study is to provide basic data for measurement of the aluminum concentration in site in hot dip zinc bath at the temperature of $460^{\circ}C\~500^{\circ}C$ using $CaF_2$ solid electrolyte sensor with three kinds of reference electrode. Good workability and stability of the sensor were confirmed with the $Bi+BiF_3$ reference electrode from the emf measurement. In order to measure the aluminum concentration in Zn-Al bath, the galvanic cell of fluorine ion was constructed with $CaF_2$ solid electrolyte as follows; $$(-)W|Zn-Al,\;AlF_3|CaF_2|Bi,BiF_3|W(+)$$. The emf measurement was made at the temperature of $460\pm10^{\circ}C$ in the Zn-Al bath. The following correlationship between aluminum concentration and emf was obtained by the least square regression analysis; $$E/mV=56.795log[\%Al]+1881.7\;R=0.9704$$,$$0.026wt\%{\leq}[\%Al]{\leq}0.984wt\%$$

• Journal of Bio-Environment Control
• /
• v.18 no.3
• /
• pp.285-290
• /
• 2009

The solid carbon dioxide used for prolongation shelf life of radish sprout that was just 7days. The developed equipment for treated carbon dioxide consisted of solid carbon dioxide evaporated part and high carbon dioxide and low temperature treated part that can hold products. The inner temperature of equipment decreased temperature to below $5^{\circ}C$ from room temperature for 10minutes and carbon dioxide concentration increased to 80%. The radish sprouts treated 4 different conditions that was nontreated condition (control), solid carbon dioxide put into package (CO2-1), solid carbon dioxide treated before storage using the developed equipment (CO2-2), solid carbon dioxide treated before storage and during storage, and sprout packaged with solid carbon dioxide (CO2-3). These radish sprout packaged with $25{\mu}m$ ceramic film stored at $8^{\circ}C$. The high carbon dioxide treatment did not affect the fresh weight loss. The carbon dioxide and oxygen content in package changed 40% and 10%, respectively in CO2-1 and CO2-2 at 1day after treatments. But carbon dioxide content of all treatments was decreased to 5% and stabilized. The high carbon dioxide showed the effect of reduction ethylene production, but did not affect to visual quality and offodor.

• Journal of the Korean Vacuum Society
• /
• v.21 no.2
• /
• pp.93-98
• /
• 2012

$Gd_{1-x}VO_4:{Eu_x}^{3+}$ phosphor powders were synthesized with changing the concentration of $Sm^{3+}$ ion by using a solid-state reaction method. The crystal structures of all the phosphors were found to be a tetragonal system, composed of (200) diffraction peak centered at $24.76^{\circ}$, and the morphology of grains approached the spherical form with homeogenous size distribution when the concentration of $Sm^{3+}$ ion was 0.05 mol. As for the photoluminescence properties, all of the phosphor powders, irrespective of $Sm^{3+}$ ion concentration, indicated the yellow, orange, and red emission peaked at 565, 603, and 645 nm respectively. As the concentration of $Sm^{3+}$ ion increases, the intensity of excitation spectrum showed a decreasing tendency on the increase of Sm3+ ion concentration. The maximum excitation and emission spectra were observed and the symmetry ratio was 1.19 at 0.05 mol of $Sm^{3+}$ ion.

• Asian-Australasian Journal of Animal Sciences
• /
• v.15 no.6
• /
• pp.821-827
• /
• 2002

The purpose of this study was to evaluate the effect of protected fat and heat-extruded soybean meal on the lactation performance of Holstein cows. Twenty-four cows, consisting of 20 lactating cows and 4 rumen-fistulated dry cows, were randomly allocated into four groups with 5 lactating cows and 1 fistulated cow in each group. A replicated 4${\times}$4 Latin square design with four 21 day periods, including 14 days of adaptation and 7 collection days within each period was employed. The experiment was a 2${\times}$2 arrangement, with or without heat-extruded soybean meal and protected fat inclusion. The dietary treatments consisted of supplements of (a) soybean meal (the control), (b) heat-extruded soybean meal, (c) protected fat, and (d) heat-extruded soybean meal and protected fat. The results showed that there were no significant differences in feed intake, milk yield, milk protein content, milk lactose content and body weight change between the dietary treatments. However, cows supplemented with protected fat showed a significantly increased (p<0.05) milk fat yield, 3.5% FCM and total solid yield. The increase in undegradable intake protein (UIP) via heat extruded soybean meal supplement significantly decreased the urea nitrogen concentration in the blood (p<0.05). Dietary fat inclusion significantly increased the blood cholesterol concentration (p<0.01) and decreased the ruminal pH value (p<0.01). Increased dietary UIP significantly decreased the ammonia nitrogen concentration in the rumen (p<0.01), but did not significantly influence the pH and VFA molar percentage in the rumen. It appears that dietary protected fat inclusion could improve milk fat and solid content. Increased dietary undegradable intake protein through heat extruded soybean meal did not improve milk yield. But it could alleviate the adverse effect of decreased milk protein due to dietary fat supplementation. Increased UIP could also decrease the ammonia nitrogen concentration in the rumen and plasma urea nitrogen concentration in the blood.