• Applied Biological Chemistry
• /
• v.19 no.2
• /
• pp.93-98
• /
• 1976

The experiment was made to investigate concentrations of $CO_2\;and\;O_2$ in the removal of astringency of persimmon fruits and to study the changes of total, reducing sugar and hardness during the removal of astringency. 1. During the removal of astringency of persimmon fruits, channel of tannin content showed the rapid decrease in high concentration of $CO_2$ and the gradual decrease in low concentration of $CO_2$. 2. Concentration of oxygen did not show effect on the removal of astringency at high concentration of $CO_2$ but at low concentration of $CO_2$ in Chungdo-Bansi. 3. Optimal concentration of the removal of astringency was $60{\sim}70%,\;CO_2$ and $6{\sim}8%\;O_2$ in Chungdo-Bansi and Sagoksi 4. In changes of sugar content total sugar was decreased and reducing sugar was increased.

• Nuclear Engineering and Technology
• /
• v.55 no.2
• /
• pp.516-522
• /
• 2023

The co-precipitation process plays a key role in the decontamination of radionuclides from low and intermediate levels of liquid waste. For that reason, the removal of Cs ions from waste solution by the co-precipitation method was carried out. A simulated liquid waste (¹³³Cs) was prepared from a 0.1 M CsCl solution, while wastewater generated by washing steel ash served as a representative of radioactive cesium solution (¹³⁷Cs). By co-precipitation, potassium ferrocyanide was applied for the adsorption of Cs ions, while nickel nitrate and iron sulfate were selected for supporting the precipitation. The amount of residual Cs ions in the CsCl solution after precipitation and filtration was determined by ICP-OES, while the radioactivity of ¹³⁷Cs was measured using a gamma-ray spectrometer. After cesium removal, the amount of cesium appearing in both XRD and SEM-EDS was analyzed. The removal efficiency of ¹³³Cs was 60.21% and 51.86% for nickel nitrate and iron sulfate, respectively. For the ash-washing solution, the removal efficiency of ¹³⁷Cs was revealed to be more than 99.91% by both chemical agents. This implied that the co-precipitation process is an excellent strategy for the effective removal of radioactive cesium in waste solution treatment.

• Clean Technology
• /
• v.14 no.1
• /
• pp.1-6
• /
• 2008

Removal of paraffin wax from a ceramic injection mold using supercritical $CO_2$ has been studied. The paraffin wax is used as a binder in the ceramic injection molding process. The effects of pressure, temperature and flow rate of supercritical $CO_2$ on the removal of the paraffin wax were investigated. The removal rates were measured with various flow rates of $CO_2$ in the range of 328.15 - 348.15 K and 15 - 30 MPa. The removal rate of paraffin wax increased as the pressure increased. In the effect of temperature, the paraffin wax was effectively removed over 329.15K (melting point of paraffin wax), however, the efffct of temperature was not significant when the temperature was further increased. The increase of $CO_2$ flow rate also affected the removal of paraffin wax. However, the effect of flow rate was not observed when the flow rate reached a certain value. Propane was used as a co solvent in order to remove the paraffin wax effectively. When the propane was added to the $CO_2$, the removal efficiency was improved. The paraffin wax was completely removed from the ceramic injection mold without any change in their shape and the structure.

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2001.04a
• /
• pp.39-40
• /
• 2001

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.4
• /
• pp.588-595
• /
• 2020

This study examined the catalytic property of Ni-catalyst used in the gas purifying process to manufacture inert gases of N2 and Ar with high-purity over 9N for semiconductor industrial applications. Two types of Ni-catalysts with a cylindrical shape (C1) and churros shape structure (C2) were compared for the assessment. Optical microscopy and FESEM were used to analyze the shape and microstructure of the Ni-catalyst. EDS, XRD, and micro-Raman characterization were performed to examine the composition and properties. BET and Pulse Titration analyses were conducted to check the surface area and catalytic property of the Ni-catalyst. From the composition analysis results, C1 contained a relatively large amount of graphite as an impurity, and C2 contained higher Ni contents than C1. From specific surface area analysis, the specific surface area of C2 was approximately 1.69 times larger than that of C1. From catalytic property analysis, outstanding performance in O₂ and CO impurity removal was observed at room temperature. Therefore, C2, having low-impurity and large specific surface area, is a suitable catalyst for the high-purity inert gas process in the semiconductor industry because of its outstanding performance in O₂ and CO impurity removal at room temperature.

• Journal of Powder Materials
• /
• v.10 no.1
• /
• pp.6-14
• /
• 2003

The purpose of the present study is to investigate the method decreasing debinding time as well as lowering operation condition than pure supercritical $CO_2$ debinding by using cosolvent or binary mixture of propane + $CO_2$. First method is to add cosolvent, such as n-hexane, DCM, methanol, 1-butanol, in supercritical $CO_2$. In case of adding cosolvent, we were found the addition of non-polar cosolvent (n-hexane) improves dramatically the binder removal rate (more than 2 times) compared with pure supercritical $CO_2$ debinding, second method is to use mixture of supercritical propane + $CO_2$, as solvent. In case of using mixture of supercritical propane + $CO_2$, the rate of debinding speeded up with increasing of pressure and concentration of propane at 348.15 K. It was found that addition of cosolvent (e.g., n-hexane, DCM) and binary mixture propane + $CO_2$ for supercritical solvent remarkably improved binder removal rate for the paraffin wax-based binder system, in comparison with using pure supercritical $CO_2$.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.1741-1744
• /
• 2005

The electron beam machining provides very high resolution up to nanometer scale, hence the E-Beam writing technology is rapidly growing in MEMS and nano-engineering areas. For E-Beam machining, $2^{nd}$ electron detector is required to see a machined sample at the stage. The $2^{nd}$ electron detector is composed of scintillator and photomultiplier with signal amplifier and high voltage power supplier. Since a photomultiplier tube is an extremely high-sensitivity photodetector, the signal light level to be detected is very low and therefore particular care must be exercised in shielding external light. In this paper, the design methodology of $2^{nd}$ electron detector and the image noise removal method are introduced.

• Proceedings of the KSME Conference
• /
• 2008.11b
• /
• pp.2116-2121
• /
• 2008

Removal of particles at rich $CO_2$ condition has been important in the gas cleaning for $CO_2$ capture in Oxy-fuel combustion. Electrostatic precipitators (ESPs) have been widely used to remove particles in exhaust gases from present air combustion. However, few studies on characteristics of ESPs under a $CO_2$ rich gas condition have been conducted. In this study, we investigated integration of electrostatic precipitators (ESP) for removing submicron particles along with corona discharge characteristics and collection efficiency of submicron particles at $CO_2$ rich condition. The overall performance of ESP is represented by collection efficiency as function of energy consumption. The experiment results showed that higher the concentration of $CO_2$ gas, the corona discharge currents were lower at the same applied voltages and the spark over occurred at lower voltages, and the collection efficiency of submicron particles under 50, 80% $CO_2$ conditions was much lower than that under 100% Air.

• Food Science and Preservation
• /
• v.6 no.4
• /
• pp.392-397
• /
• 1999

The quality changes during the removal of astringecy by CO$_2$gas at 2$^{\circ}C$ and 20$^{\circ}C$ of three varieties of persimmons named 'Tonewase', 'Chungdobanshi' and 'Sagokshi' were examined. Astringency index and tannin content showed rapid decrease at 20$^{\circ}C$ and gradual decrease at 2$^{\circ}C$. All was edible 2days from the removal of astringency at 20$^{\circ}C$, while 'Tonewase' and 'Sagokshi' were edible on 6days and 'Chungdobanshi' on 10days after treatment at 2$^{\circ}C$. Soluble solid contents was decreased a little(1∼3%) during the removal of astringency. Hardness was decreased slowly but, kept over 1.0kg/$\phi$5mm till edible period in all varieties at 2$^{\circ}C$ and 20$^{\circ}C$. The hardness of 'Chungdobanshi' was kept well after the removal of astringency at 2$^{\circ}C$. No noticeable color changes in all varieties during treatment. Injury fruits were noticeable in only 'Tonewase' after the removal of astringency treatment at 2$^{\circ}C$.

• Applied Chemistry for Engineering
• /
• v.27 no.1
• /
• pp.1-9
• /
• 2016

The co-culture system of microalgae and bacteria enables simultaneous removal of BOD and nutrients in a single reactor if the pair of microorganisms is symbiotic. In this case, nutrients are converted to biomass constituents of microalgae. This review highlights the importance and recent researches using symbiotic co-culture system of microalgae and bacteria in wastewater treatment, focusing on the removal of nitrogen and phosphorus. During wastewater treatment, the microalgae produces molecular oxygen through photosynthesis, which can be used as an electron acceptor by aerobic bacteria to degrade organic pollutants. The released $CO_2$ during the bacterial mineralization can then be consumed by microalgae as a carbon source in photosynthesis. Microalgae and bacteria in the co-culture system could cooperate or compete each other for resources. In the context of wastewater treatment, positive relationships are prerequisite to accomplish the sustainable removal of nutrients. Therefore, the selection of compatible species is very important if the co-culture has to be utilized in wastewater treatment.