• Journal of Practical Agriculture & Fisheries Research
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• v.17 no.1
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• pp.93-100
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• 2015

This study was performed to examine the high temperature adaptability with CO₂ treatment for tomato under the condition of greenhouse cultivation during summer season. The indoor condition of CO₂ concentrations were controlled as control, 500 ppm, and 1,000 ppm for the greenhouse with the maximum air temperature of 44℃. With the observation of VPD (vapor pressure deficit) and CWSI (crop water stress index) by leaf-air temperature difference according to CO₂ treatment concentration, the plants with the CO₂ concentration of 1,000 ppm performed less water stress than those with the CO₂ concentrations of control and 500 ppm. The plants without CO₂ treatment performed the severest degree of water stress.

• Clean Technology
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• v.15 no.2
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• pp.69-74
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• 2009

A high-dose ion-implanted photoresist (HDIPR) was stripped off from the surface of a semiconductor wafer by using a mixture of supercritical carbon dioxide and a co-solvent. The additional ultrasonication improved the stripping efficiency remarkably and thus reduced the stripping time by supplying physical force to the substrate. We investigated the effect of co-solvents, co-solvent concentration, and stripping temperature and pressure on the stripping efficiency. The wafer surfaces before and after stripping were analyzed by scanning electron microscopy and by an energy dispersive X-ray spectrometer. The HDIPR could be stripped off completely in 3 min with 10%(w/w) acetone/sc$C0_2$ mixture at 27.6 MPa and 343 K.

• Journal of the Korean Institute of Gas
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• v.9 no.3 s.28
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• pp.49-54
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• 2005

This work was to calibrate Anton Paar 512P vibrating tube densimeter which is a special type for density measurement under high pressure (up to 70 MPa) and temperature (up to 420 K) and checked the validity of the new apparatus. Calibration was peformed with water, nitrogen and water, vacuum as reference fluids. Temperature is measured from 313.15 K and 353.15 K at 10 K intervals, and pressure is measured up to 30 MPa at 5 MPa intervals, respectively. To check the validity of new apparatus and the calibration method we compared the values obtained by measuring density of carbon dioxide with those given by NIST Thermophysical Properties of Pure Fluids Database. The average deviations between the NIST and the experimental data were $0.3\%$ with water and nitrogen as reference fluids.

• Journal of the Korean Society for Marine Environment & Energy
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• v.19 no.1
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• pp.52-61
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• 2016

To inject huge amount of $CO_2$ for CCS application, high pressure pipeline transport is accompanied. Rapid depressurization of $CO_2$ pipeline is required in case of transient processes such as accident and maintenance. In this study, numerical analysis on the depressurization of high pressure $CO_2$ pipeline was carried out. The prediction capability of the numerical model was evaluated by comparing the benchmark experiments. The numerical models well predicted the liquid-vapor two-phase depressurization. On the other hands, there were some limitations in predicting the temperature behavior during the supercritical, liquid phase and gaseous phase expansions.

• Korean Journal of Mineralogy and Petrology
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• v.34 no.3
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• pp.169-176
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• 2021

This study aimed to fundamentally understand structural changes of zeolite under pressure and in the presence of different pressure-transmitting media (PTM) for application studies such as immobilization of heavy metal cation or CO₂ storage using pressure. High-pressure X-ray powder diffraction study was conducted on the zeolite-W (K_6.4Al_6.5Si_25.8O₆₄× 15.3H₂O, K-MER) to understand linear compressibility and the bulk moduli in different PTM conditions. Zeolite-w is a synthetic material having the same framework as natural zeolite merlinoite ((K, Ca_0.5, Ba_0.5, Na)₁₀ Al₁₀Si₂₂O₆₄× 22H₂O). The space group of the sample was identified as I4/mmm belonging to the tetragonal crystal system. Water, carbon dioxide, and silicone-oil were used as pressure-transmitting media. The mixture of sample and each PTM was mounted in a diamond anvil cell (DAC) and then pressurized up to 3 GPa with an increment of ca. 0.5 GPa. Pressure-induced changes of powder diffraction patterns were measured using a synchrotron X-ray light source. Lattice constants, and bulk moduli were calculated using the Le-Bail method and the Birch-Murnaghan equation. In all PTM conditions, linear compressibility of c-axis (𝛽^c) was 0.006(1) GPa^-1 or 0.007(1) GPa^-1. On the other hand, the linear compressibility of a(b)-axis (𝛽^a) was 0.013(1) GPa^-1 in silicone-oil run, which is twice more compressible than the a(b)-axis in water and carbon dioxide runs, 𝛽^a = 0.006(1) GPa^-1. The bulk moduli were measured as 50(3) GPa, 52(3) GPa, and 29(2) GPa in water, carbon dioxide, and silicone-oil run, respectively. The orthorhombicities of ac-plane in the water, and carbon dioxide runs were comparatively constant, near 0.350~0.353, whereas the value decreased abruptly in the silicone-oil run following formula, y = -0.005(1)x + 0.351(1) by non-penetrating pressure fluid condition.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.1294-1299
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• 2009

Since the operating pressure of $CO_2$ gascooler is so high compared with that of previous subcritical condenser, the optimization of gascooler is needed for improve heat exchanger performance. In this study, the performance characteristics of five kinds of heat exchangers were analyzed and compared with operating conditions. As a result, the 4-20 HX-tube shows the maximum gascooler capacity because the heat transfer is effective and pressure drop is small. Beside, the high performance of 4-20 HX-tube could be keep for wide operating condition.

• Korean Chemical Engineering Research
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• v.43 no.3
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• pp.432-437
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• 2005

An electric swing adsorption (ESA) process for recovering highly pure $CO_2$ from the mixed gases was tested. In this study, activated carbon fibers were used as an adsorbent. The activated carbon fibers showed fast adsorption rate and the high adsorption capacity for $CO_2$ adsorption under the condition of the ambient pressure. Activated carbon fiber with higher specific surface area was suitable to repeated adsorption-desorption cycle process, showing consistent breakthrough curve. Especially, the regeneration method by vacuum combined with ESA improved the performance of desorption process by an additional 17％ regeneration efficiency compared to a vacuum only method, and showed the high regeneration efficiency at comparatively low 7-8 Wh energy.

• Food Science and Biotechnology
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• v.15 no.1
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• pp.13-18
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• 2006

Mandarin juice was processed using a continuous high pressure $CO_2$ system. Response surface methodology was used to investigate the effects of the processing parameters such as temperature, pressure, residence time, and %(w/w) ratio of $CO_2$ to juice on total aerobic count (TAC), pectinesterase (PE) activity, cloud level, $^{\circ}Brix$, pH, and titratable acidity (TA) of the juices. Maximum log reduction (3.47) of TAC was observed at $35^{\circ}C$, 41.1 MPa, 9 min residence time, and 7% $CO_2$. PE was inactivated by 7-51%. The cloud was not only retained but was also enhanced by 38%. Lightness and yellowness increased, and redness decreased. The processing temperature and % $CO_2$/juice ratio significantly affected high pressure $CO_2$ processing of the juice in terms of pasteurization, PE inactivation, cloud increase, and color change. The $^{\circ}Brix$, pH, and TA before and after treatment remained unchanged.

• Bulletin of the Korean Chemical Society
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• v.19 no.12
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• pp.1351-1355
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• 1998

A simple apparatus for adding a modifying solvent to supercritical CO2 extractant was described. Small, fixed volumes (typically 100 μL) of liquid modifying solvents were delivered during the extraction process by use of an in-line high pressure loop injector and an air pump. Without disconnecting the extraction cell from the supercritical fluid extraction system, the modifying solvent was repeatedly delivered. The solvent modification device was optimized during the extraction of carbaryl and bis(acetylacetonato) copper(Ⅱ). Extraction recoveries from spiked filter paper and soil samples ranged between 22% and 109%, depending on the analyte and matrix components. The addition of polar modifying solvents were necessary to improve the extractability of the nonpolar CO2.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.609-614
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• 2005

Gas hydrates are ice-l ike sol id compounds that are composed of water and natural gas. All common gas hydrates belong to the three crystal structures that are composed of five polyhedral cavities formed by hydrogen bonded water molecules and stable in specific high pressure and low temperature conditions. Gas hydrates contain large amounts of organic carbon and widely occur in deep oceans and permafrost regions, and they may therefore represent a potential energy resource in the future. United States and Japan perform the national R&D programs for the commercial production of gas hydrates in 2010's. The study on gas hydrates are also important for exploration and development of natural gas in the regions where gas hydrates are accumulated and could be formed. Although their global abundance is debated, they play an important role in global climate change since methane is a 50 times more effect ive greenhouse gas than carbon dioxide. Natural gas hydrates also form a possible natural hazard if rapidly dissociated and can cause slides and slumps and in the marine environment associated tsunamis.