• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.2
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• pp.1005-1012
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• 2011

This research carried out a 3-dimensional simulation using computerized fluid dynamics (CFD) for the flow characteristics, temperature distribution, velocity distribution and residence time, etc. in a reactor in order to derive the optimal combustion conditions of an innovative combustion system. The area-weighted average temperature of the outlet of a furnace during combustion at a condition of fuel input rate 1.5 ton/hr, residence time 1.25 sec and air/fuel ratio 2.1 was $1,077^{\circ}C$, which is a suitable temperature for energy recovery and treatment of air pollutants. Exhaust gas is discharged through a duct at a 40~50 m/s maximum speed along strong vortexes at the center of a combustion chamber, so strong turbulence is created at the center of a combustion chamber to enhance the combustion speed and combustion efficiency. In this system, the optimum operation conditions to prevent incomplete combustion and suppress the formation of thermal NOx were air/fuel ratio 1.9~2.1 and fuel input rate 1.25~1.5 ton/hr.

• KSBB Journal
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• v.10 no.2
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• pp.212-220
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• 1995

An obligatory type II methanotroph Methylosinus trichosporium OB3b was cultivated on methanol as a sole carbon and energy source. The effects of methanol concentration, pH, temperature, nitrogen source and phosphate concentration on cell growth were investigated and the results were compared with the growth on methane, which had been studied previously. When $(NH_4)_2SO_4$ was used as a nitrogen source, the maximal specific growth rate (${\mu}max$) on methanol was $0.20hr^{-1}$ and the carbon conversion efficiency(CCE) was 43%. In comparison, on methane, ${\mu}max$ and CCE were $0.08hr^{-1}$ and 32%, respectively. Ammonia was found to be a better nitrogen source for methanol-growing cells. Cell yield on nitrogen (YX/N) was the same regardless of nitrogen source as 7.14g dry cells/g N, but the yield on methanol(YX/N) was higher with ammonia(0.8g dry cells/g MeOH) than with nitrate(0.64g dry cells/g MeOH). Optimal pH and temperature were 7.0 and $30^{\circ}C$, respectively. Methanol inhibition on cell growth was observed at above 0.5%(v/v). Inhibition by phosphate was observed at above 60mM, although the inhibition on methanol dehydrogenase activity started at a much lower level of 20mM. Based on the experimental findings, the cellular physiology of M. trichosporium OB3b growing on the two closely-related carbon sources were discussed extensively.

• Asian-Australasian Journal of Animal Sciences
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• v.8 no.4
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• pp.393-402
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• 1995

Experiments were conducted to evaluate the nutritive values of supplemental L-lysine, liquid and powder type, and DL-methionine in weanling pigs. For feeding trial, 165 weanling pigs were treated in 2 controls; 18 and 16% CP, 6 supplementations of lysine alone to 16% CP diets; 0.1, 0.2 and 0.4% of liquid and powder type each, and 3 supplementations of lysine + methionine to 15% CP diets; 0.05 + 0.025, 0.1 + 0.05 and 0.2 + 0.1%. Pigs were fed for 5 week to investigate the protein sparing effect of supplemental amino acid, and the optimal supplemental level. A metabolic trial included the measurements of digestibilities of dry matter, crude protein, crude fat, crude fiber, energy, phosphorus and amino acids. The liver acinar cell culture was conducted for the protein synthesis activity of the pigs fed each experimental diet. Supplementation of both type of L-lysine in 16% CP diet showed improved daily weight gain and feed efficiency which were compatible with those of pigs fed 18% CP diet. Groups fed liquid lysine did not differ from those fed powder type in growth performance. Supplementation of lysine and methionine to 15% CP diet did not improve growth performance of pigs to the extent that 18% CP diet was fed. In nutrient digestibility, 16% CP control diet showed significantly (p < 0.05) lower crude protein digestibility than any other treatments. Digestibilities of 16% CP diets with lysine supplementation were equal to that of 18% CP control, while digestibilities of 15% CP diets with the supplementation of lysine + methionine was inferior to that of 18% CP control. Supplementation of lysine alone reduced the nitrogen excretion compared to the none supplemented control groups. However, addition of lysine + methionine excreted more nitrogen than controls. Pigs fed diet supplemented with lysine alone, or lysine + methionine excreted less fecal phosphorus than those fed none supplemetation. Retained protein from liver tissue of pigs fed 18% diet was significantly (p < 0.05) greater than those fed 16% CP diet. A significant difference (p < 0.05) was observed in physical type of lysine. Feeding of powder type showed less secreted protein and greater retained protein in the culture of liver acinar cell. It is concluded that supplementation of lysine at the level of 0.1 to 0.2% can spare 2% of dietary protein and reduce nitrogen excretion by 19.3%. Also, no difference in nutritional values was observed between liquid and powder lysine in weanling pigs.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.25 no.3
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• pp.89-94
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• 2019

Among the many packaging materials used in cushion packaging, there is a lack of optimum design for the tray cup pad used in fruit packaging for export and domestic distribution. It causes over-packaging due to excessive material input, and this could be solved by applying various parameters needed to optimize the design of the tray cup pad considering the packaging material and the quantity of fruits in the box. In the case of a tray cup for fruits, the economic efficiency of material and thickness should be considered. Therefore, it is possible to design a tray cup pad depending on the packaging material used by applying appropriate design parameters. The static and dynamic characteristics of the materials used for packaging of pears were analyzed by using the FEM (finite element Method) simulation technique to derive the optimal design parameters. And by applying the appropriate design parameters considering the quantity of fruit and distribution environment, it is possible to design an appropriate fruit tray cup pad. In this study, as a result of simulating the contact stresses between the fruit and the tray cup for the PP, PE, and PS materials used in the fruit tray cup, the material with the lowest contact stress was PP and the value was found to be 398 Pa. The contact displacement between fruit and tray cup using this material was about 0.0463 mm, which was the lowest value compared with other materials. Also the resonance frequency band of tray cup made of PP material was below 36.81 Hz, and the strain energy was below 12.20 J. The resonant frequency band of the pear is more than 80 Hz and it could be applied to all the tray cup materials as compared with the resonance band of 38.81 Hz or less which is the resonance band of all tray cup pads for packaging. Finally, PP is the most suitable material for the tray cup pad.

• Asian-Australasian Journal of Animal Sciences
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• v.12 no.6
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• pp.908-913
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• 1999

This experiment was conducted in three trials to evaluate optimal ambient temperature for a novel milk replacer feeding system designed for early-weaned pigs, compared to commercial dry diets fed within a conventional hot nursery. A total of 165 PIC genotype pigs were weaned at $13.89{\pm}0.7$ days of age and allotted to one of two dietary treatments in three trials based on weight and litter origin. Each trial consisted of pigs fed dry diets (DD) and pigs fed milk replacer (MR) which was offered in one of 3 different ambient temperatures. Pigs fed milk replacer were housed in a specialized nursery building in which one half of each pen contained an enclosed hover that was thermostatically maintained at $32^{\circ}C$ while the exterior ambient temperature (where milk was fed) was set at either 17 (trial 1), 24 (trial 2) or $32^{\circ}C$ (trial 3). Pigs fed dry diets with the conventional nursery were maintained at $30^{\circ}C$ for each trial. From d 21 to d 49, all pigs were fed DD within a standardized hot nursery environment. During the first week (d 14-21), pigs fed MR showed increased ADG from 214% to 228% over control pigs fed DD (p<0.001), regardless of ambient temperature. As ambient temperature was increased from 17 to 24 to $32^{\circ}C$, ADG of MR-fed pigs was increased by 214%, 220% and 228% over those of pigs fed DD, respectively. ADFIs of MR-fed pigs at $17^{\circ}C$, $24^{\circ}C$, and $32^{\circ}C$ compared with pigs fed DD were increased by 108%, 139% and 164% from d 14 to d 21, respectively. Fed efficiency (G/F) of MR-fed pigs at $17^{\circ}C$, $24^{\circ}C$, and $32^{\circ}C$ compared with pigs fed DD were 199%, 162% and 139% of those of pigs fed DD, respectively. As ambient temperature increased, diarrhea scores showed a slight tendency to increase. The advantage of MR feeding was greater when the ambient temperature was higher, but G/F was impaired with increased ambient temperature. We conclude that ambient temperature within the specialized nursery influenced behavior, MR feed intake, and probably piglet energy expenditure. There were no differences between MR-fed and DD-fed pigs for ADG, ADFI and G/F in the subsequent growth period (d 21 to d 49, p>0.05). Maximal advantage of MR feeding was obtained at the intermediate ($24^{\circ}C$) ambient temperature during the overall period (p<0.05). Results from this experiment indicate that a milk replacer feeding system utilized in the early postweaning period can maximize pig growth performance, and that ADG, ADFI and G/F were affected by different ambient temperatures within MR-fed pigs. The high or low temperatures could not support the maximal growth of pigs fed MR.

• Korean Journal of Microbiology
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• v.36 no.4
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• pp.279-284
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• 2000

Simultaneous reduction of Cr(VI) and degradation of phenol was observed in batch and bench-scale continuous stirred tank reactors using Rhodococcus sp. CP01 isolated from leachate. The strain CP01, which was capable of utilizing phenol as a sole source of carbon and energy, completely reduced added hexavalent chromium (0.25 mM) to its trivalent form during 60 hr batch assay under optimal conditions (pH 7.0 and 1,000 mg/L of phenol concentration). The rates of Cr(VI) reduction and phenol degradation were estimated as 4.17 $\mu$M Cr(VI) and 38.4 mg phenol.$L^{-1}{\cdot}hr^{-1}$, respectively. The continuous culture experiment was conducted for 46 days using synthetic feed containing different levels of chromate (0.0625 to 0.25 mM) and phenol(1,000 to 4,000 mg/L). With a hydraulic retention time of 100 hr, Cr(VI) reduction efficiency was mostly 100% for influent Cr(VI) and phenol concentrations of 0.125 mM and 3,000 mg/L, respectively. During quasi-steady-state operation, specific rate of Cr(VI) reduction was calculated as 0.34 mg Cr(VI).g $protein^{-1}{\cdot}hr^{-1}$ which was comparable to reported values obtained by using glucose as growth substrate. The results suggest the potential application of biological treatment for detoxification of wastewater contaminated simultaneously with Cr(VI) and pheonol.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.443-450
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• 2019

We studied to find the optimal manufacturing conditions of coffee grounds sludge RDF with oil drying method. We expanded the lab scale to pilot scale to compare the efficiency of the oil-drying equipment and The selection of the ratio of coffee grounds and oil, the setting temperature, and the temperature change and water content with time were measured. In order to analyze the characteristics of the research results, characteristics of solid fuels produced(Coffee grounds of oil-dried) by calorimeter, TGA, combustion equipment, and combustion gas measuring instrument were analyzed. As a result, the ratio of oil to coffee grounds was 4: 1, and when the setting temperature was set to $300^{\circ}C$, the water content reached 10wt.% or less within 20 minutes. ln addition, it showed high calorific value of 6,273kcal/kg. However, coffee grounds had a similar composition to wood and showed high luminance and produced a lot of CO in combustion gas. As a result, it is considered to be unsuitable for thermoelectric power plant and camping fuel, but the initial ignition speed is high and the heat generation is high, so it is considered that it can replace the fuels for current use.

• Journal of the Korean Society of Urban Environment
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• v.18 no.4
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• pp.401-408
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• 2018

EQPS (Effluent Quality Prediction System, Dynamita, France) was applied to analyze the appropriateness of the design of a bioreactor in A sewage treatment plant. A sewage treatment plant was designed by setting the design concentration of the secondary clarifier effluent to total nitrogen and total phosphorus, 10 mg/L and 1.8 mg/L, respectively, in order to comply with the target water quality at the level of the hydrophilic water. The retention time of the 4-stage BNR reactor was 9.6 hours, which was 0.5 for the pre-anoxic tank, 1.0 for the anaerobic tank, 2.9 for the anoxic tank, and 5.2 hours for the aerobic tank. As a result of the modeling of the winter season, the retention time of the anaerobic tank was increased by 0.2 hours in order to satisfy the target water quality of the hydrophilic water level. The default coefficients of the one step nitrification denitrification model proposed by the software manufacturer were used to exclude distortion of the modeling results. Since the process modeling generally presents optimal conditions, the retention time of the 4-stage BNR should be increased to 9.8 hours considering the bioreactor margin. The accurate use of process modeling in the design stage of the sewage treatment plant is a way to ensure the stability of the treatment performance and efficiency after construction of the sewage treatment plant.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.7
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• pp.1951-1975
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• 2023

Recent advances in Cognitive Radio Networks (CRN) have elevated them to the status of a critical instrument for overcoming spectrum limits and achieving severe future wireless communication requirements. Collaborative spectrum sensing is presented for efficient channel selection because spectrum sensing is an essential part of CRNs. This study presents an innovative cooperative spectrum sensing (CSS) model that is built on the Firefly Algorithm (FA), as well as machine learning artificial neural networks (ANN). This system makes use of user grouping strategies to improve detection performance dramatically while lowering collaboration costs. Cooperative sensing wasn't used until after cognitive radio users had been correctly identified using energy data samples and an ANN model. Cooperative sensing strategies produce a user base that is either secure, requires less effort, or is faultless. The suggested method's purpose is to choose the best transmission channel. Clustering is utilized by the suggested ANN-FA model to reduce spectrum sensing inaccuracy. The transmission channel that has the highest weight is chosen by employing the method that has been provided for computing channel weight. The proposed ANN-FA model computes channel weight based on three sets of input parameters: PU utilization, CR count, and channel capacity. Using an improved evolutionary algorithm, the key principles of the ANN-FA scheme are optimized to boost the overall efficiency of the CRN channel selection technique. This study proposes the Artificial Neural Network with Firefly Algorithm (ANN-FA) for cognitive radio networks to overcome the obstacles. This proposed work focuses primarily on sensing the optimal secondary user channel and reducing the spectrum handoff delay in wireless networks. Several benchmark functions are utilized We analyze the efficacy of this innovative strategy by evaluating its performance. The performance of ANN-FA is 22.72 percent more robust and effective than that of the other metaheuristic algorithm, according to experimental findings. The proposed ANN-FA model is simulated using the NS2 simulator, The results are evaluated in terms of average interference ratio, spectrum opportunity utilization, three metrics are measured: packet delivery ratio (PDR), end-to-end delay, and end-to-average throughput for a variety of different CRs found in the network.

• Clean Technology
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• v.30 no.2
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• pp.105-112
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• 2024

Globally, the demand for electric vehicles has surged due to greenhouse gas regulations related to climate change, leading to an increase in the production of used batteries as a consequence of the battery life issue. This study aims to selectively leach and recover valuable metal lithium from the cathode material of spent LFP (LiFePO₄) batteries among lithium-ion batteries. Generally, the use of inorganic acids results in the emission of toxic gases or the generation of large quantities of wastewater, causing environmental issues. To address this, research is being conducted to leach lithium using organic acids and other leaching agents. In this study, selective leaching was performed using the organic acid methane sulfonic acid (MSA, CH₃SO₃H). Experiments were conducted to determine the optimal conditions for selectively leaching lithium by varying the MSA concentration, pulp density, and hydrogen peroxide dosage. The results of this study showed that lithium was leached at approximately 100%, while iron and phosphorus components were leached at about 1%, verifying the leaching efficiency and the leaching rates of the main components under different variables.