• Resources Recycling
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• v.21 no.6
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• pp.32-38
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• 2012

In this study, direct reduction of $ZrO_2$ using liquid calcium was investigated. The influence of molar ratio of Ca and $ZrO_2$, reaction time and temperature on the reduction behavior of $ZrO_2$ was studied. Experiments were conducted in a closed stainless steel chamber under Ar atmosphere during 5 to 60 minutes. Most of the $ZrO_2$ was reduced to Zr in 5 minutes at 1223 K and 3 Ca/$ZrO_2$ molar ratio. The minimum oxygen content in reduced metal Zr was obtained about 0.66 wt% at 1373 K after 30 minutes and 4 Ca/$ZrO_2$ molar ratio. The morphology of zirconium powder obtained was highly affected by the reaction temperature and reaction time.

• Journal of Korea Foundry Society
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• v.35 no.5
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• pp.114-119
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• 2015

This paper reports the effect of a refractory crucible type on the microstructure of duplex stainless steel (DSS) cast with the addition of gadolinium using air-induction melting. Grade 4A DSSs with 1 wt% of gadolinium (Gd) were fabricated in various crucibles including alumina ($Al_2O_3$), magnesia (MgO), calcia (CaO) coated with yttria ($Y_2O_3$) and graphite. The standard free energies of the formation of calcium and yttrium oxide were lower than those of gadolinium oxide and other crucible elements based oxide. The yield of Gd in DSS using $Al_2O_3$, MgO, CaO-coated $Y_2O_3$ and graphite was 5, 19, 83 and 96%, respectively. As Gd yield increased, the amount of Gd-based inclusions increased, the size of the inclusions were reduced, and the inclusions became evenly distributed.

• Archives of Pharmacal Research
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• v.29 no.4
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• pp.298-301
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• 2006

This study was investigated the bactericidal effects of calcium oxide (CaO) on three common foodborne pathogenic bacteria: Escherichia coli, Listeria monocytogenes, and Salmonella typhimurium. Each bacteria level was determined in a CaO solution (0.01, 0.03, 0.05, 0.10, 0.15, and $0.20\%$ [w/v]) exposed for either 15 sec, 30 sec, 1 min, 2 min, 3 min, 5 min, 10 min, or 30 min. All three bacteria were not greatly affected by CaO solutions at concentrations of 0.01 and $0.03\%$, however, the decline of E. coli $(99\%;\;2.78\;log_{10}CFU/mL)$, L. monocytogens $(45\%;\;1.44\;log_{10}CFU/mL)$, and S. typhimurium $(70\%;\;2.08\;log_{10}CFU/mL)$ was greatest when they were exposed to $0.05\%$ CaO solution for 10 min. Moreover, the bactericidal action of CaO was maintained for at least 24 h of storage. The results of this study provide evidence that CaO, as a substitute for synthetic chemical substances has potential for use in the disinfection and sanitization of foods and food processing equipment.

• Resources Recycling
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• v.26 no.6
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• pp.38-44
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• 2017

As by-pass dust (BPD) made from cement manufactured process is designated waste, it is required to bury as high cost. The main component of BPD is potassium chloride (KCl), and used for the fertilizer. For using KCl to the fertilizer, the pH value of KCl is required as neutral or weak acid. However, it is not suitable to apply BPD into the fertilizer directly without any other treatment because BPD's pH value is shown 12.0~12.5; a high base. In this study, the carbon dioxide ($CO_2$) was used for removing calcium oxide (CaO) and reducing pH value during manufacturing process of KCl. We fixed inner condition of the carbon test chamber as $25^{\circ}C$-50RH%, and retained 0~7 hours under the 20 vol% of $CO_2$ atmosphere. After experiment, we analyzed the content of CaO and pH value from each samples. The more time exposed to $CO_2$, the content of CaO and pH value are shown. Furthermore, pH value exposed in 6 hours nearly reached 7.

• Journal of the Society of Naval Architects of Korea
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• v.61 no.1
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• pp.51-60
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• 2024

Hi Air Korea and Hanwha ocean are currently developing an Onboard Carbon dioxide Capture System (OCCS) to absorb CO₂ emitted from ship's engine using a sodium hydroxide(NaOH) solution, and converting the resulting salt into a solid form through a chemical reaction with calcium oxide (CaO). The system process involves the following steps; 1)The reaction of CO₂ gas absorption in water, 2)The reaction between carbonic acid (H₂CO₃) and NaOH solution to produce carbonate or bicarbonate, and 3)The reaction between carbonate or bicarbonate and CaO to form calcium carbonate (CaCO₃). And ultimately, the solid material, CaCO₃, is separated and discharged using a separator. The OCCS has been installed on an ship and the test results have confirmed significant reduction effects of CO₂ in the ship's exhaust gas. A portion of the exhaust gas emitted from the engine was transferred to the OCCS using a blower. The flow rate of the transferred gas ranged from 800 to 1384 m³/hr, and the CO₂ concentration in the exhaust gas was 5.1 vol% for VLSFO, 3.7 vol% for LNG and a 12 wt% NaOH solution was used. The results showed a CO₂ capture efficiency of approximately 42.5 to 64.1 vol% and the CO₂ capture rate approximately 48.4 to 52.2kg/hr. Additionally, to assess the impact of the discharged CaCO₃on the marine ecosystem, we conducted "marine ecotoxicity test" and performed Computational Fluid Dynamics (CFD) analysis to evaluate the dispersion and dilution of the discharged effluent.

• Bulletin of the Korean Chemical Society
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• v.28 no.6
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• pp.1049-1052
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• 2007

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2002.05a
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• pp.219-222
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• 2002

석탄연소 순환유동층 연소로에서 석회석을 이용한 SO$_2$의 제거는 이미 기술적으로 입증된 방법이다. 연소로에 투입된 석회석은 식(1)과 같은 소성반응을 거친 후 CaO로 변화하며 식(2)와 같은 황화(sulfation)반응에 의해 SO$_2$를 흡수하여 CaSO$_4$ 형태로 변화한다.(중략)

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.11
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• pp.550-554
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• 2001

$(Ba_{0.6}Sr_{0.4}Ca_x)TiO_3 + yAl_2O_3$ wt% (x=0.10, 0.15, 0.20, y=0~3.0) ceramics were fabricated by the mixed-oxide method, and their structural and dielectric properties were investigated with variation of composition ratio and $Al_2O_3$ doping content. As results of the X-ray diffraction and microstructure analysis, all BSCT specimens showed dense and homogeneous structure without presence of the second phase. The sintered density was decreased with an increase of $Al_2O_3$ doping content. The Curie temperature and relative dielectric constant at room temperature were decreased with increasing $Al_2O_3$doping content. The dielectric loss is minimum at BSCT doped with 1.5wt% $Al_2O_3$content. The tunability was decreased with increasing an Ca content and the BSCT(50/40/10) specimen doped with 2.0wt% $Al_2O_3$content showed the maximum value of 4.2%.

• Journal of Food Hygiene and Safety
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• v.28 no.3
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• pp.227-233
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• 2013

In this study, we evaluated the ability of various disinfectants to suppress the growth of microorganisms in fresh-cut products and organic vegetable. The growth of more than 50% of B. cereus isolates were suppressed by 50% ethanol, 0.1% hydrogen peroxide, 0.4% sodium hypochlorite or 1% calcium oxide. E. coli generally showed high susceptibility to concentration of 10% ethanol, 0.4% sodium hypochlorite and 1% calcium oxide. Eighty percent or more of S. aureus isolates exhibited resistance to ethanol, hydrogen peroxide and sodium hypochlorite, but the isolates were susceptible to concentrations of 1% calcium oxide. All isolates evaluated in this study were sensitive to benzalkonium chloride (BAC) and growth in the presence of $2.0{\mu}g/mL$ of BAC was completely inhibited. These pathogens showed widely different susceptibilities to different organic acids. Greater than 0.5% acetic acid and 2% and higher concentrations of malic acid and tartaric acid inhibited the growth of 60% of the isolates of B. cereus. Two percent acetic acid and tartaric acid inhibited 50% of the S. aureus isolates. Seventy percent of the E. coli isolates were resistant to malic acid and susceptible to 1% acetic acid and 10% tartaric acid. The antibacterial effects of the various sanitizers evaluated in this study were not only dependent on the type of disinfectant but also on the pathogen. Thus, it is important to select a sanitizer that is safe and effective at removing specific types of microorganisms.

• Journal of Animal Science and Technology
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• v.63 no.4
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• pp.841-853
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• 2021

This study aimed to investigate the effects of Kimchi cabbage by-products either treated or untreated with calcium oxide (CaO) and alkaline hydrogen peroxide (AHP) as substitutional ingredient of total mixed ration (TMR) on in vitro fermentation, in situ disappearance and growth performance of Holstein steers. Cannulated Holstein (600 ± 47 kg) was used for both the in vitro and in situ experiments. The treatments used were TMR only (CON), TMR + 30% Kimchi cabbage by-products fresh matter (FM) basis (TC), TMR + 30% Kimchi cabbage by-products FM basis + 5% CaO FM basis (TCC), and TMR + 30% Kimchi cabbage by-products FM basis + 5% CaO FM basis + 3.22% AHP FM basis (TCCA). For in vivo experiment, thirty-four Holstein steers (273 ± 45 kg) were subjected to a 150-day feeding trial, divided into two groups: CON and TC. In the in vitro experiment, pH of TCCA was greatest (p < 0.05) among other treatments at all incubation times. Ammonia nitrogen and volatile fatty acid concentrations were not significantly different for each treatment. However, butyrate was greater (p < 0.05) in TCC and CON than in both TC and TCCA. During in situ experiment, the dry matter (DM) disappearance was greatest (p < 0.05) in TCCA among other treatments. Also, disappearance of neutral detergent fiber (NDF) and acid detergent fiber (ADF) were observed greatest (p > 0.05) in TCCA treatment. In the in vivo experiment, average daily gain (ADG) did not differ between CON and TC. In blood profile analysis, alanine aminotransferase, aspartate aminotransferase, glucose, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and total protein concentration were not significantly different between treatments. But, creatinine concentration was greater (p < 0.05) in TC than in CON. Overall results suggest that Kimchi cabbage by-products either treated or untreated with CaO and AHP can be used as substitutional ingredient in TMR for Holstein steers.