• Journal of Korean Society of Forest Science
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• v.111 no.1
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• pp.177-185
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• 2022

In this study, the economic feasibility of a local energy facility that uses forest biomass as an energy source was assessed. We analyzed profitability using data from the Forest Energy Self-sufficient Village Project financed by the Korea Forest Service. The energy facility has a cogeneration generator and wood chip boiler. Wood chip, which has lower heat value and is cheaper than wood pellets, is used as fuel. Revenue comes from the sale of electricity, heat, and renewable energy certificates. Additionally, we considered the sale of carbon credits as substitutes for fossil fuels. The expenditure consists of fuel costs and fixed costs, and the initial investment is treated as a sunk cost. Under the condition of a 55% operation rate and wood chip price of 95,000 KRW per ton, the annual net revenue is positive. Crucial factors for managing the facility sustainably are operation rate and fuel cost. A simulation in which two factors were changed showed that the annual net revenue is negative with a 50% operation rate and 100,000 KRW per ton of wood chip price. To improve net revenue, an increase in the operation rate or a decrease in the wood chip price is required. Additionally, selling carbon credits will make the operation of the facility more profitable. Furthermore, the payment required to procure wood chips could contribute to the rural economy. To foster the use of forest biomass for energy, the price for heat supplied from renewable energy sources should be subsidized.

• Journal of the Korean Chemical Society
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• v.27 no.3
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• pp.194-200
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• 1983

Effect of metallic salts added to the ${\alpha}-Fe_2O_3-HCl\;or\;{\alpha}-Fe_2O_3-H_2SO_4$ reaction systems were investigated by colorimetric and gravimetric determinations. While reductive salts exhibited remarkably enhanced reaction rate, non-reductive salts showed inhibitive results. We supposed that the improvement of dissolution rate of ${\alpha}-Fe_2O_3$ by the addition of $FeCl_2$, a reductive salt, to the ${\alpha}-Fe_2O_3-HCl$ system can be attributed to the formation of chloro-bridge between $Fe^{3+}\;and\; Fe^{2+}$, and therefore some partial electronic charge transfer from $Fe^{2+}\;to\;Fe^{3+}$ on the surface of ${\alpha}-Fe_2O_3$ will be easily achieved through the bridged bond. The transferred charge to the surface will reduce the positive charge of initial $Fe^{3+}$, and also result to reduce the lattice energy of that site. Assuming tothat there is a linear relationship between the lattice energy change and the change of activation energy of the reaction system, the transferred partial electronic charge to $Fe^{3+}$ of ${\alpha}-Fe_2O_3$ surface was calculated to be ca. 0.36e.

• Environmental Engineering Research
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• v.24 no.3
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• pp.389-396
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• 2019

The electrical energy consumption (EEC) in removal of NO by a $UV/H_2O_2$ oxidation process was introduced and related to removal efficiency of this gas. The absorption-reaction of NO was conducted in a bubble column reactor in the presence of $SO_2$. The variation in NO removal efficiency was investigated for various process parameters including NO and $SO_2$ inlet concentrations, initial concentration of $H_2O_2$ solution and gas flow rate. EEC values were obtained in these different conditions. The removal efficiency was increased from about 22% to 54.7% when $H_2O_2$ concentration increased from 0.1 to 1.5 M, while EEC decreased by about 70%. However, further increase in $H_2O_2$ concentration, from 1.5 to 2, had no significant effect on NO absorption and EEC. An increase in NO inlet concentration, from 200 to 500 ppm, decreased its removal efficiency by about 10%. However, EEC increased from $2.9{\times}10^{-2}$ to $3.9{\times}10^{-2}kWh/m^3$. Results also revealed that the presence of $SO_2$ had negative effect on NO removal percentage and EEC values. Some experiments were conducted to investigate the effect of $H_2O_2$ solution pH. The changing of pH of oxidation-absorption medium in the ranges between 3 to 10, had positive and negative effects on removal efficiency depending on pH value.

• Journal of Animal Science and Technology
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• v.66 no.2
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• pp.340-352
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• 2024

This study measured the potential changes of the microbiota in the gastrointestinal tract and energy and nutrient digestibility by supplemental bacteriophages in pigs. Twelve castrated male pigs (initial mean body weight = 29.5 ± 2.3 kg) were surgically cannulated using T-cannula. The animals were housed individually in pens equipped with a feeder and a nipple waterer. The pigs were allotted to 1 of 3 experimental diets in a quadruplicated 3 × 2 Latin square design with 3 experimental diets, 2 periods, and 12 pigs resulting in 8 replicates per diet. The 3 diets were a control mainly based on corn and soybean meal with no antibiotics or bacteriophages, a diet containing 0.1% antibiotics, and a diet containing 0.2% bacteriophages. On day 5 of the experimental period, feces were collected and on days 6 and 7, ileal digesta were collected. Genomic DNA for bacteria were extracted from the ileal digesta and feces and the V4 region of the 16S rRNA gene was amplified. The ileal and fecal digestibility of energy, dry matter, organic matter, crude protein, and fiber was unaffected by dietary antibiotics or bacteriophages. At the phylum level, the supplemental antibiotic or bacteriophage tended to result in a higher proportion of Firmicutes (p = 0.059) and a lower proportion of Bacteroidetes (p = 0.099) in the ileal digesta samples compared with the control group with no difference between the antibiotic and bacteriophage groups. At the genus level, the supplemental antibiotic or bacteriophage tended to result in a higher proportion of Lactobacillus (p = 0.062) and a lower proportion of Bacteroides (p = 0.074) and Streptococcus (p = 0.088) in the ileal digesta compared with the control group with no difference between the antibiotic and bacteriophage groups. In the feces, supplemental antibiotics or bacteriophages reduced the proportion of Bifidobacterium compared with the control group (p = 0.029) with no difference between the antibiotic and bacteriophage groups. Overall, supplemental antibiotics and bacteriophages showed positive effect on the microbiota of in the ileal digesta without largely affecting energy or nutrient digestibility, with no differences between the antibiotic and bacteriophage groups in growing pigs.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.9
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• pp.623-629
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• 2011

The adsorption characteristics of tricyclazole by granular activated carbon were experimently investigated in the batch adsorption. Kinetic studies of adsorption of tricyclazole were carried out at 298, 308 and 318 K, using aqueous solutions with 250, 500 and 1,000 mg/L initial concentration of tricyclazole. It was established that the adsorption equilibrium of tricyclazole on granular activated carbon was successfully fitted by Freundlich isotherm equation at 298 K. The pseudo first order and pseudo second order models were used to evaluate the kinetic data and the pseudo second order kinetic model was the best with good correlation. Values of the rate constant ($k_2$) have been calculated as 0.1076, 0.0531, and 0.0309 g/mg h at 250, 500 and 1,000 mg/L initial concentration of tricyclazole, respectively. Thermodynamic parameter such as activation energy, standard enthalpy, standard entropy and standard free energy were evaluated. The positive value for enthalpy, -66.43 kJ/mol indicated that adsorption interaction of tricyclazole on activated carbon was an exothermic process. The estimated values for standard free energy were -5.08~-8.10 kJ/mol over activated carbon at 200 mg/L, indicated toward a exothermic process.

• Clean Technology
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• v.17 no.4
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• pp.346-352
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• 2011

The adsorption characteristics of propineb pesticide onto activated carbon has been investigated for the adsorption in aqueous solution with respect to initial concentration, contact time and temperature in batch experiment. The Langmuir and Freundlich adsorption models were applied to described the equilibrium isotherms and isotherm constants were also determined. The Freundlich model agrees with experimental data well. slope of isotherm line indicate that activated carbon could be employed as effective treatment for removal of propineb. The pseudo first order, pseudo second order kinetic models were use to describe the kinetic data and rate constants were evaluated. The adsorption process followed a pseudo second order model, and the adsorption rate constant($k_2$) decreased with increasing initial concentration of propineb. The activation energy, change of free energy, enthalpy, and entropy were also calculated to predict the nature adsorption. The estimated values for change of free energy were -7.28, -8.27 and -11.66 kJ/mol over activated carbon at 298, 308 and 318 K, respectively. The results indicated toward a spontaneous process. The positive value for change of enthalpy, 54.46 kJ/mol, found that the adsorption of propineb on activated carbon is an endothermic process.

• Environmental Engineering Research
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• v.15 no.3
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• pp.141-147
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• 2010

The objective of this study was to assess the biofouling characteristics of the Bacillus biofilm formed on reverse osmosis (RO) membranes. For the study, a sporogenic Bacillus sp. was isolated from the seawater intake to a RO process, with two distinct sets of experiments performed to grow the Bacillus biofilm on the RO membrane using a lab-scale crossflow membrane test unit. Two operational feds were used, 9 L sterile-filtered seawater and 109 Bacillus cells, with flow rates of 1 L/min, and a constant 800 psi-pressure and pH 7.6. From the results, the membrane with more fouling, in which the observed permeate flux decreased to 33% of its initial value, showed about 10 and 100 times greater extracellular polymeric substances and spoOA genes expressions, respectively, than the those of the less fouled membrane (flux declined to 20% of its initial value). Interestingly; however, the number of culturable Bacillus sp. in the more fouled membrane was about 10 times less than that of the less fouled membrane. This indicated that while the number of Bacillus had less relevance with respect to the extent of biofouling, the activation of the genes of interest, which is initiative of biofilm development, had a more positive effect on biofouling than the mass of an individual Bacillus bacterium.

• Computers and Concrete
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• v.19 no.5
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• pp.489-499
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• 2017

Self-Compacting Concrete (SCC) is a new technology capable to flow without segregation or any addition of energy which leads to efficient construction and cost savings. In this study, the effect of replacing the Ordinary Portland Cement (OPC) with Fly Ash (FA) on the strength, durability of the concrete was investigated experimentally, and carbon footprint and cost were also assessed. Four different replacement FA ratios (0%, 20%, 40% and 60%) were used to create four SCC mixes. Standard test methods were used to determine the workability, strength, and durability of the SCC mixes including resist chloride ion penetration, water permeability, water absorption, and initial surface absorption. The axial cube compressive strength tests were performed on the SCC mixes at 1, 7, 14, 28 and 35 days. Replacing the OPC with FA had a significant positive impact on chloride iron penetration resistance and water absorption but had a considerable negative impact on the compressive strength. The SCC mix with 60% FA had 36.7% and 15.8% enhancement in the resistance to chloride ion penetration and water absorption, respectively. Evaluation of the carbon footprint and the cost of each SCC mixes showed the $CO_2$ emissions mixes 1, 2, 3 and 4 were significantly reduced by increasing the FA content from 0% to 60%. Compared with the control mix, the cost of all mixes increased when the FA content increased, but no significant differences were seen between the estimated costs of all four mixes.

• Journal of Microbiology and Biotechnology
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• v.24 no.4
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• pp.453-464
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• 2014

The current research was focused on the extracellular biosynthesis of bactericidal silver nanoparticles (AgNPs) using cell-free supernatant of a local isolate previously identified as a novel Streptomyces aegyptia NEAE 102. The biosynthesis of silver nanoparticles by Streptomyces aegyptia NEAE 102 was quite fast and required far less time than previously published strains. The produced particles showed a single surface plasmon resonance peak at 400 nm by UV-Vis spectroscopy, which confirmed the presence of AgNPs. Response surface methodology was chosen to evaluate the effects of four process variables ($AgNO_3$ concentration, incubation period, pH levels, and inoculum size) on the biosynthesis of silver nanoparticles by Streptomyces aegyptia NEAE 102. Statistical analysis of the results showed that the linear and quadratic effects of incubation period, initial pH, and inoculum size had a significant effect (p < 0.05) on the biosynthesis of silver nanoparticles by Streptomyces aegyptia NEAE 102. The maximum silver nanoparticles biosynthesis (2.5 OD, at 400 nm ) was achieved in runs number 5 and 14 under the conditions of 1 mM $AgNO_3$ (1-1.5% (v/v)), incubation period (72-96 h), initial pH (9-10), and inoculum size (2-4% (v/v)). An overall 4-fold increase in AgNPs biosynthesis was obtained as compared with that of unoptimized conditions. The biosynthesized silver nanoparticles were characterized using UV-VIS spectrophotometer and Fourier transform infrared spectroscopy analysis, in addition to antimicrobial properties. The biosynthesized AgNPs significantly inhibited the growth of medically important pathogenic gram-positive (Staphylococcus aureus) and gram-negative bacteria (Pseudomonas aeruginosa) and yeast (Candida albicans).

• Bulletin of the Korean Chemical Society
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• v.2 no.2
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• pp.71-75
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• 1981

Vacuum ultraviolet photolysis of ethyl bromide was studied at 104.8-106.7 nm (11.4-11.6 eV) in the pressure range of 0.2-18.6 torr at $25^{\circ}$ using an argon resonance lamp with and without additives, i.e., NO and He. Since the ionization potential of $CH_3CH_2Br$ is lower than the photon energy, the competitive processes between the photoionization and the photodecomposition were also investigated. The observations indicated that 50% of absorbed light leads to the former process and the rest to the latter one. In the absence of NO the principal reaction products for the latter process were found to be $CH_4, C_2H_2, C_2H_4, C_2H_6, and C_3H_8$. The product quantum yields of these reaction products showed two strikingly different phenomena with an increase in reactant pressure. The major products, $C_2H_4$ and $C_2H_6$, showed positive effects with pressure whereas the effects on minor products were negative in both cases, i.e., He and reactant pressures. Addition of NO completely suppresses the formation of all products except $C_2H_4$ and reduces the $C_2H_4$ quantum yield. These observations are interpreted in view of existence of two different electronically excited states. The initial formation of short-lived Rydberg transition state undergoes HBr molecular elimination and this state can across over by collisional induction to a second excited state which decomposes exclusively by carbon-bromine bond fission. The estimated lifetime of the initial excited state was ${\sim}4{\times}10^{-10}$ sec. The extinction coefficient for $CH_3CH_2Br$ at 104.8-106.7 nm and $25{\circ}$ was determined to be ${varepsilon} = (1/PL)ln(I_0/I_t) = 2061{\pm}160atm^{-1}cm6{-1}$ with 95% confidence level.