• Animal Bioscience
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• v.37 no.2
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• pp.173-183
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• 2024

Objective: This study aimed to evaluate whether the methane (CH₄) to carbon dioxide (CO₂) ratio (CH₄/CO₂) and methane-related traits obtained by the sniffer method can be used as indicators for genetic selection of Holstein cows with lower CH₄ emissions. Methods: The sniffer method was used to simultaneously measure the concentrations of CH₄ and CO₂ during milking in each milking box of the automatic milking system to obtain CH₄/CO₂. Methane-related traits, which included CH₄ emissions, CH₄ per energy-corrected milk, methane conversion factor (MCF), and residual CH₄, were calculated. First, we investigated the impact of the model with and without body weight (BW) on the lactation stage and parity for predicting methane-related traits using a first on-farm dataset (Farm 1; 400 records for 74 Holstein cows). Second, we estimated the genetic parameters for CH₄/CO₂ and methane-related traits using a second on-farm dataset (Farm 2; 520 records for 182 Holstein cows). Third, we compared the repeatability and environmental effects on these traits in both farm datasets. Results: The data from Farm 1 revealed that MCF can be reliably evaluated during the lactation stage and parity, even when BW is excluded from the model. Farm 2 data revealed low heritability and moderate repeatability for CH₄/CO₂ (0.12 and 0.46, respectively) and MCF (0.13 and 0.38, respectively). In addition, the estimated genetic correlation of milk yield with CH₄/CO₂ was low (0.07) and that with MCF was moderate (-0.53). The on-farm data indicated that CH₄/CO₂ and MCF could be evaluated consistently during the lactation stage and parity with moderate repeatability on both farms. Conclusion: This study demonstrated the on-farm applicability of the sniffer method for selecting cows with low CH₄ emissions.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.19 no.2
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• pp.225-231
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• 2021

The reaction between Li₂CO₃ and Cl₂ was investigated to verify its occurrence during a carbon-anode-based oxide reduction (OR) process. The reaction temperature was identified as a key factor that determines the reaction rate and maximum conversion ratio. It was found that the reaction should be conducted at or above 500℃ to convert more than 90% of the Li₂CO₃ to LiCl. Experiments conducted at various total flow rate (Q) / initial sample weight (W_i) ratios revealed that the reaction rate was controlled by the Cl₂ mass transfer under the experimental conditions adopted in this work. A linear increase in the progress of reaction with an increase in Cl₂ partial pressure (pCl₂) was observed in the pCl₂ region of 2.03-10.1 kPa for a constant Q of 100 mL·min^-1 and W_i of 1.00 g. The results of this study indicate that the reaction between Li₂CO₃ and Cl₂ is fast at 650℃ and the reaction is feasible during the OR process.

• Transactions of the Korean hydrogen and new energy society
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• v.23 no.6
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• pp.581-587
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• 2012

Thermal aging effect on NSR kinetics was studied over Pt/Co/Fe/Ba/$Al_2O_3$ catalyst. The amount of $NO_x$ uptake over Pt/Co/Fe/Ba/$Al_2O_3$ calcined at $400^{\circ}C$ increased with increasing NSR temperature from $200^{\circ}C$ to $400^{\circ}C$, where amount of $NO_x$ uptake is the highest at $400^{\circ}C$ with mol ratio of $NO_x$/Ba = 0.5. Thereafter, the amount of $NO_x$ uptake at $400^{\circ}C$ decreased with the higher calcination temperature, where Pt/Co/Fe/Ba/$Al_2O_3$ catalyst calcined at $700^{\circ}C$ showed an amount of $NO_x$ uptake with the mol ratio of $NO_x$/Ba=0.062. Result of XRD and NSR showed that Fe addition into Pt/Co/Fe/Ba/$Al_2O_3$ suppressed sintering of Pt crystallites and make $NO_x$ uptake larger, compared to no addition of Fe into Pt/Co/Fe/Ba/$Al_2O_3$ catalyst. From BET result, it was found that the change of specific surface area was relatively small by the thermal aging process. Therefore, it was found that the sintering of Pt crystallites caused the decrease of $NO_x$ uptake during NSR reaction and Fe played a role to suppress the sintering process of Pt crystallites caused by thermal aging.

• Journal of Powder Materials
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• v.25 no.4
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• pp.296-301
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• 2018

In this study, an experiment is performed to recover the Li in $Li_2CO_3$ phase from the cathode active material NMC ($LiNiCoMnO_2$) in waste lithium ion batteries. Firstly, carbonation is performed to convert the LiNiO, LiCoO, and $Li_2MnO_3$ phases within the powder to $Li_2CO_3$ and NiO, CoO, and MnO. The carbonation for phase separation proceeds at a temperature range of $600^{\circ}C{\sim}800^{\circ}C$ in a $CO_2$ gas (300 cc/min) atmosphere. At $600{\sim}700^{\circ}C$, $Li_2CO_3$ and NiO, CoO, and MnO are not completely separated, while Li and other metallic compounds remain. At $800^{\circ}C$, we can confirm that LiNiO, LiCoO, and $Li_2MnO_3$ phases are separated into $Li_2CO_3$ and NiO, CoO, and MnO phases. After completing the phase separation, by using the solubility difference of $Li_2CO_3$ and NiO, CoO, and MnO, we set the ratio of solution (distilled water) to powder after carbonation as 30:1. Subsequently, water leaching is carried out. Then, the $Li_2CO_3$ within the solution melts and concentrates, while NiO, MnO, and CoO phases remain after filtering. Thus, $Li_2CO_3$ can be recovered.

• Journal of the Korean Electrochemical Society
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• v.18 no.4
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• pp.137-142
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• 2015

$Mn_{1+X}Co_{2-X}O_4$ solid solutions with various Mn/Co ratios were synthesized by a combustion method, and used as cathode catalysts for lithium/air secondary battery. Their electrochemical and physicochemical properties were investigated. The morphology was examined by transmission electron microscopy (TEM), and the crystallinity was confirmed by X-ray diffraction (XRD) analyses. For the measurement of electrochemical properties, charge and discharge measurements were carried out at a constant current density of $0.2mA/cm^2$, monitoring the voltage change. Electrochemical impedance spectroscopy (EIS) analyses were also employed to examine the change in charge transfer resistance during charge-discharge process. $Mn_{1+X}Co_{2-X}O_4$ solid solutions showed enhanced cycleability as a cathode of Li/air secondary battery, and the performance was found to be strongly dependent on Mn/Co ratio. Among synthesized catalysts, $Mn_{1.5}Co_{1.5}O_4$ exhibited the best performance and cycleability, due to high charge transfer rate.

• The KSFM Journal of Fluid Machinery
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• v.14 no.2
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• pp.41-46
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• 2011

This study investigated the changes in performance and operating characteristics of an F-class gas turbine according to the change of working fluid from air to carbon dioxide. The revised gas turbine is the topping cycle of the semi-closed oxy-fuel combustion combined cycle. With the same turbine inlet temperature, the $CO_2$ gas turbine is expected to produce about 85% more power. The main contributor is the greater compressor mass flow and the added oxygen flow for the combustion. Compressor pressure ratio increases about 50%. However, the gas turbine efficiency reduces about 10 %. Modulation of inlet guide vane to reduce the compressor inlet mass flow, the major purpose of which is to reduce the compressor inlet Mach number, was also performed.

• Journal of the Korean Applied Science and Technology
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• v.32 no.4
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• pp.712-717
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• 2015

In this study, the experiment of CO production was performed using carbon dioxide and coal. The synthesis characteristics of CO gas was investigated using the chemical activation method of KOH. The preparation process has been optimized through the analysis of experimental variables such as activating chemical agents to coal ratio, the flow rate of gas and reaction temperature during $CO_2$ conversion reaction. Without the catalyst of KOH, the 66.7% of $CO_2$ conversion was obtained at the conditions of $T=950^{\circ}C$ and $CO_2$ flow rate of 300 cc/min. On the other hand, the 98.1% of $CO_2$ conversion was obtained using catalyst of KOH at same conditions. It was found that the feed ratio(Coal : KOH = 4 : 1) had better $CO_2$ conversion and CO selectivity than other feed ratios.

• Journal of Magnetics
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• v.15 no.1
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• pp.25-28
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• 2010

This study examined the crystallographic and magnetic properties of vanadium-substituted lithium cobalt titanium ferrite, $Li_{0.7}Co_{0.2}Ti_{0.2}V_{0.2}Fe_{1.7}O_4$. Ferrite was synthesized using a conventional ceramic method. The samples annealed below $1040^{\circ}C$ showed X-ray diffraction peaks for spinel and other phases. However, the sample annealed above $1040^{\circ}C$ showed a single spinel phase. The lattice constant of the sample was $8.351\;{\AA}$, which was relatively unaffected by vanadium-substitution. The average grain size after vanadium-substitution was $13.90\;{\mu}m$, as determined by scanning electron microscopy. The M$\ddot{o}$ssbauer spectrum could be fitted to two Zeeman sextets, which is the typical spinel ferrite spectra of $Fe^{3+}$ with A and B sites, and one doublet. From the absorption area ratio of the M$\ddot{o}$ssbauer spectrum, the cation distribution was found to be ($Co_{0.2}V_{0.2}Fe_{0.6})[Li_{0.7}Ti_{0.2}Fe_{1.1}]O_4$. Vibrating sample magnetometry revealed a saturation magnetization and coercivity of 36.9 emu/g and 88.6 Oe, respectively, which were decreased by vanadium-substitution.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.11
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• pp.1186-1191
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• 2004

ZnO varistor ceramics which were fabricated with variation of added of 0.5～1.0 mol% Co$_3$O$_4$, were sintered at 1150 $^{\circ}C$. In the specimen added 0.7 mol% Co$_3$O$_4$, sintered density was 6.03 g/㎤ and electrical properties were superior to any other compositions. The nonlinear coefficient a and clamping voltage ratio were 83 and 1.35, respectively. But, endurance surge current in the specimen added 0.5 mol% Co$_3$O$_4$ was 7000 A/$\textrm{cm}^2$, and deviation of varistor voltage was Δ-3.23 %. As P.C.T and T.C.T environmental test were succeed in all specimens, and deviation of varistor voltage in the specimen added 0.6 mol% Co$_3$O$_4$ was Δ-0.81 %. All specimens showed good leakage current property on the High Temperature Continuous Load Test(HTCLT) for 1000 hr at 85 $^{\circ}C$ and variation rate of the varistor voltage below Δ-2.0 %.

• Journal of the Korean Electrochemical Society
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• v.16 no.2
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• pp.59-64
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• 2013

Using $Na_2CO_3$ and $MeSO_4$ (Me = Ni, Co and Mn) as starting materials, the precursor of $[Ni_{0.6}Co_{0.2}Mn_{0.2}]CO_3$ has been synthesized by carbonate co-precipitation. The precursor was mixed with $Li_2CO_3$, and calcined at 750, 850, and$950^{\circ}C$ in air. Effect of calcinations temperature on characteristics of $Li[Ni_{0.6}Co_{0.2}Mn_{0.2}]O_2$ cathode materials was investigated. The structure and characteristics of $Li[Ni_{0.6}Co_{0.2}Mn_{0.2}]O_2$ were determined by X-ray diffraction (XRD), Scanning electron microscopy (SEM) and electrochemical measurements. The X-ray diffraction (XRD) results show that the intensity ratio of $I_{(003)}/I_{(104)}$ increased and the R-factor ratio decreased with the increase of calcinations temperature. And Scanning electron microscopy (SEM) result show that the primary particle size increased. Especially, the $Li[Ni_{0.6}Co_{0.2}Mn_{0.2}]O_2$ calcined at $950^{\circ}C$ for 24 H shows excellent electrochemical performances with reversible specific capacity of $165.3mAhg^{-1}$ [cut-off voltage 2.5~4.3 V, 0.1 C($17mAhg^{-1}$)] and good capacity retention of 95.4% after 50th charge/discharge cycles[cut-off voltage 2.5~4.3 V, 1 C($170mAhg^{-1}$)].