• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.19 no.12
• /
• pp.1402-1409
• /
• 2008

In this paper, a low temperature co-fired ceramic cavity backed antenna in order to improve the performances of radiation and bandwidth for the antenna with high relative dielectric constant is proposed. Low temperature co-fired ceramic cavity consisted of several ground planes with closely spaced metallic vias connected. It is shown that the size of a low temperature co-fired ceramic cavity has the effects on the performances of radiation and bandwidth for the antenna. The proposed 2x4 low temperature co-fired ceramic cavity backed antenna is $10{\times}20\;mm^2$ in size. Measured results show antenna gain of $11.8{\sim}14.1\;dBi$ and bandwidth of 13 %(7.9 GHz) in the $57{\sim}64\;GHz$ band.

• Transactions of the Korean hydrogen and new energy society
• /
• v.35 no.2
• /
• pp.140-145
• /
• 2024

High temperature co-electrolysis of H₂O-CO₂ mixtures using solid oxide cells has attracted attention as promising CO₂ utilization technology for production of syngas (H₂/CO), feedstock for E-fuel synthesis. For direct supply to E-fuel production such as hydrocarbon and methanol, the outlet gas ratio (H₂/CO/CO₂) of co-electrolysis should be controlled. In this work, current voltage characteristic test and product gas analysis were carried out under various reaction conditions which could attain proper syngas ratio.

• Journal of Korean Society of Environmental Engineers
• /
• v.36 no.3
• /
• pp.185-191
• /
• 2014

In this paper, absorption and reaction characteristics of low $CO_2$ and alkanolamines were investigated. As MEA concentrations increase 1, 2 and 3 wt%, $CO_2$ loadings decrease 0.34 mol-$CO_2/mol$-absorbent, 0.32 mol-$CO_2/mol$-absorbent and 0.3 mol-$CO_2/mol$-absorbent, respectively. Also, $CO_2$ loadings decrease from 0.32 mol-$CO_2/mol$-absorbent, 0.30 mol-$CO_2/mol$-absorbent and 0.28 mol-$CO_2/mol$-absorbent as AMP concentrations increase 1, 2 and 3 wt%. Experimental results with blending solutions show that $CO_2$ loading was the highest, 0.52 mol-$CO_2/mol$-absorbent, when 0.5 wt% MEA and 0.5 wt% AMP were blended.

• Atmosphere
• /
• v.20 no.3
• /
• pp.307-318
• /
• 2010

This study investigates the generation and movement of low-concentration $CO_2$ observed in Gosan during summer from 2002 to 2006. For analysis, additional $CO_2$ data in Anmyeondo, Ryori, Barrow, and Minamitorishima as well as NOAA/ESRL daily global $CO_2$ fields, background trajectories data, and 850 hPa wind fields are also used. Based on analyses using various observed data, we classified three types of low-concentration $CO_2$ in Gosan according to its origin: i) the origin of the Siberian continental, in which the consumption of $CO_2$ is active due to photosynthesis from broad forests, ii) the origin of Okhotsh and Artic seas, in which the low-concentration $CO_2$ is dominant due to high primary productivity by a plankton bloom, and iii) the origin of the Northwestern Pacific which is related to the entry of air mass from high latitudes. These results show that the low-concentration $CO_2$ observed in Gosan during summer is not originated from the Pacific oceans as known in previous studies, but originated from high latitude regions such as the Siberian continental and the Okhotsh and Artic seas.

• Asian-Australasian Journal of Animal Sciences
• /
• v.16 no.4
• /
• pp.588-595
• /
• 2003

The optimum level of fresh granulated low-calcium (0.2%) skim milk co-precipitate, as fat substitute in low-fat ground pork patties was determined on the basis of physico-chemical, cooking and sensory properties. Low-fat ground pork patties (<10% total fat), formulated with 15 per cent water, 4 per cent added fat, 1.5 per cent salt and 4-10 per cent milk co-precipitate, were evaluated for proximate composition, cooking characteristics and compared with control patties with 15 % added fat. The moisture and protein content of raw and cooked low-fat patties were significantly (p<0.05) higher than control. The incorporation of milk co-precipitate in low-fat patties improved cooking yield, fat and moisture retention and reduced shrinkage. The sensory properties of low-fat patties were comparable with control patties. The overall acceptability of low-fat patties formulated with 7% milk co-precipitate was significantly (p<0.05) higher than patties with 10% level and non-significantly (p<0.05) higher than low-fat patties containing 4% milk co-precipitate and control. Instrumental Texture Profiles of developed low-fat patties and control patties were comparable with slight increases in hardness and gumminess of the low-fat product. The developed low-fat ground pork patties (7% milk co-precipitate) had lower TBA values, better microbiological and sensory refrigerated storage stability than high-fat control patties packaged in air permeable films for 21 days.

• Journal of the Korean Applied Science and Technology
• /
• v.33 no.3
• /
• pp.466-473
• /
• 2016

In this study, the experiments on optimal CO gas synthesis were conducted using low grade coal-$CO_2$ catalyst gasification reaction. The characteristics of generated CO gas were investigated using the chemical activation method of KOH, $K_2CO_3$, $Na_2CO_3$ catalysts with Kideco and Shewha coal. The preparation process has been optimized through the analysis of experimental variables such as ratio between activating chemical agents and coal, the flow rate of gas and reaction temperature during $CO_2$ conversion reaction. The produced CO gas was analysed by Gas Chromatography (GC). The 98.6% $CO_2$ conversion for Kideco coal mixed with 20 wt% $Na_2CO_3$ and 98.9% $CO_2$ conversion for Shenhua coal mixed with 20 wt% KOH were obtained at the conditions of $T=950^{\circ}C$ and $CO_2$ flow rate of 100 cc/min. Also, the low grade coal-$CO_2$ catalytic gasification reaction showed the CO selectivities(97.8 and 98.8 %) at the same feed ratio and reaction conditions.

• Journal of Sensor Science and Technology
• /
• v.17 no.4
• /
• pp.303-307
• /
• 2008

$NiO,\;Cu_2O,\;Mn_2O_3$ and $Cr_2O_3$ as p-type semiconductors were added in CoO with 15 wt.% ethylene glycol binder and measured the butane gas sensing characteristics. The highest sensitivity is obtained for the NiO-CoO sensors. CoO-20 at.% NiO sensor with 15 wt.% ethylene glycol binder sintered at $1100^{\circ}C$ for 24 h exhibits high sensitivity of 90 % to 5000 ppm butane gas at the sensor temperature of $250^{\circ}C$, compared to low sensitivities at the low operating temperature for commercial sensors. Response and recovery times are, respectively, within few seconds and 1min in the static flow system, indicating rapid adsorption and desorption of butane gas on sensor surface even at this low temperature.

• Applied Chemistry for Engineering
• /
• v.22 no.3
• /
• pp.312-318
• /
• 2011

We have investigated the kinetics and catalytic activity of $CO_2$-lignite gasification with various metal precursors as catalysts. $K_2CO_3$, $Mn(NO_3)_2$, and $Ce(NO_3)_3$ were used and impregnated on a coal using an evaporator. The gasification experiments were carried out with the low rank coal loaded with 5 wt% catalyst at the temperature range from $700{\sim}900^{\circ}C$ and atmospheric pressure with the $N_2-CO_2$ reactant gas mixture. The catalytic effect on the gasification rate of the low rank coal with $CO_2$ was determined by the thermogravimetric analyzer. It was observed that the low rank coal reached the complete carbon conversion regardless of the kinds of catalysts at $900^{\circ}C$ from the results of TGA. The catalytic activity was ranked as 5 wt% $K_2CO_3$ > 5 wt% $Mn(NO_3)_2$ > 5 wt% $Ce(NO_3)_3$ > Non-catalyst at $900^{\circ}C$. The gasification rate increased with increasing the temperature. The activation energy of the catalytic gasification with 5 wt% $K_2CO_3$ was 119.0 kJ/mol, which was the lowest among all catalysts.

• KSBB Journal
• /
• v.14 no.1
• /
• pp.109-113
• /
• 1999

Supercritical $CO_2$ chromatography was applied for purification of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) from fish oil. Various supercritical $CO_2$ pressures were tested to find out the pressure effects on solubility and selectivity of low fatty acids in the silver nitrate column. The solubility of low fatty acids was increased as the supercntical $CO_2$ Pressure increased. However, the selectiviy between low fatty acids and EPA waw decreased. Stepwise density gradient method was applied to increase the purification efficiency of EPA. Low fatty acids were easily separated at the early elution steps with low $CO_2$ densities. Successive fractions containing 92.1~97.8% of EPA were collected. The average concentration of three purified fractions was 95.6% with the recovery rate of 30%.

• Journal of Plant Biology
• /
• v.25 no.3
• /
• pp.105-111
• /
• 1982

These studies were undertaken to elucidate the reasons for the low productivity of ginseng by comparing the rate of $CO_2$-fixation and photorespiration, variation in the amounts of intermediates and enzyme activities of glycolate oxidase and catalase in ginseng with those of potato. The ability of $CO_2$-fixation in ginseng was found to be one half of that of potato and there were significant differences between those two plants in the rate of $^{14}C$ incorporated into glutamate, aspartate, malate and 3-PGA, but little differences in P-glycolate, glycolate, serine and glycine. The ratio of photorespiration to dark respiration and the activities of glycolate oxidase and catalase in the two species were about same, but ginseng showed higher ratio in photorespiration to total $CO_2$-fixation than potato did. These results indicated that the low productivity of ginseng may resulted from the low $CO_2$-fixation ability and high rate of photorespiration.