• Fire Science and Engineering
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• v.16 no.3
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• pp.26-31
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• 2002

Bromotrifluoromethane(halon-1301) and bromochlorodifluoromethane(halon-1211) have been widely used as a clean fire extinguishing agents due to their outstanding properties. However, production and use of halon are currently being phased out under an international agreements Montreal Protocol because of global environmental concerns and HFCs have been considered as promising alter-natives for the replacement of halon since their ozone depletion potentials are low. The vapor-liquid equilibrium data are required as important basic information in evaluating the solubility of clean fire extinguishing agents and determining their optimal compositions. In this work, we chose HFCs such as HFC-22 HFC-125, and HFC-l34a for gaseous fire extinguishing agents and nitrogen as a pressurization gas for a proper jet velocity of these agents. Phase equilibria for binary mixtures of nitrogen/HFC-22, nitrogen/HFC-125, and nitrogen/HFC-l34a were measured in the temperature range from 283.15K to 303.15K. For equilibrium measurement, we used a circulation type apparatus in which both vapor and liquid phases were continuously recirculated. The experimental data were relatively well correlated with the Peng-Robinson equation of state with Wong-Sandier mixing rules.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.5
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• pp.816-822
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• 1997

The immobilization of a microorganism has been rapidly progressed with the development of biotechnology in recent years. Although it has been used as a tool to isolate products from biological media in various areas, it has not yet been practiced in the treatment of waste water. In this paper, we suggest a possibility to apply the immobilization technique In the recirculating aquaculture system. We examined the ability of $NH_4^+$ removal by nitrifier consortium immobilized in $Ba^{++}-alginate$, k-carrageenan and agar bead at the concentration of 50 g/L, respectively. In order to use the immobilized nitrifier consortium as media in the fludized bed reactor, the strength of bead was measured. $Ba^{++}-alginate$ as a support material showed higher strength of bead. Also, the nitrifier consortium immobilized in $Ba^{++}-alginate$ showed higher nitrification activity that could remove 20 mg/L ammonium ion than those immobilized in other two support materials, carrageenan and agar. The immobilized nitrifier consortium showed better nitrification activity than free nitrifier consortium.

• Korean Journal of Soil Science and Fertilizer
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• v.34 no.5
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• pp.365-372
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• 2001

The objective of this study was to determine the effects of various kinds of composts on the change of soil physical properties and microorganism in upland soils. Field experiments were conducted in the loam and sandy loam soils, while the clay loam and sandy loam soils were used for laboratory experiments. Various kinds of composts such as poultry manure compost(PMC). cow manure compost(CMC). human excrement sludge(HES), and food industrial sludge compost(FISE) were applied annually at rates of 0, 40, and $80Mg\;ha^{-1}$ to soils grown with soybean and maize plants for 4 years during 1994 to 1997. The results of this study were as follows : Bulk density of loam soil decreased with compost application to $1.07{\sim}1.32Mg\;m^{-3}$ compared with $1.49Mg\;m^{-3}$ of control plot, while in sandy loam soil it decreased to $1.00{\sim}1.20Mg\;m^{-3}$ compared with $1.25Mg\;m^{-3}$ of control plot. Bulk density of soil was decreased according to maize cultivation compared with bare control, but soybean cultivation was similar. Population of organic material decomposing microorganisms was increased rapidly at the initial incubation stage at $25^{\circ}C$, and increased more sensitively at the loam soil than sandy loam soil. In the case of the change of microorganisms associated with nitrogen circulation, ammonia oxidizing bacteria was more at the initial incubation stage, and denitrifying bacteria was more at the initial incubation stage, and denitrifying bacteria increased until 1~4 weeks after incubation and increased more at the loam soil than sandy loam soil.

• Korean Journal of Environmental Agriculture
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• v.36 no.2
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• pp.73-79
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• 2017

BACKGROUND: Carbonized biomass is a carbon-rich solid product obtained by the pyrolysis of biomass. It has been suggested to mitigate climate change through increased carbon storage and reduction of greenhouse gas emission. The objective of this study was to evaluate carbon dioxide ($CO_2$) and nitrous oxide ($N_2O$) emissions from soil after carbonized biomass addition. METHODS AND RESULTS: The carbonized biomass was made from a pyrolyzer, which a reactor was operated about $400{\sim}500^{\circ}C$ for 5 hours. The treatments were consisted of a control without input of carbonized biomass and two levels of carbonized biomass inputs as 6.06 Mg/ha for CB-1 and 12.12 Mg/ha for CB-2. Emissions of $CO_2$ and $N_2O$ from orchard soil were determined using closed chamber for 13 weeks at $25^{\circ}C$ of incubation temperature. It was shown that the cumulative $CO_2$ were $209.4g\;CO_2/m^2$ for CB-1, $206.4g\;CO_2/m^2$ for CB-2 and $214.5g\;CO_2/m^2$ for the control after experimental periods. The cumulative $CO_2$ emission was similar in carbonized biomass input treatment compared to the control. It was appeared that cumulative $N_2O$ emissions were $4,478mg\;N_2O/m^2$ for control, $3,227mg\;N_2O/m^2$ for CB-1 and$ 2,324mg\;N_2O/m^2$ for CB-2 at the end of experiment. Cumulative $N_2O$ emission contents significantly decreased with increasing the carbonized biomass input. CONCLUSION: Consequently the carbonized biomass from byproducts such as pear branch residue could suppress the soil $N_2O$ emission. The results fromthe study imply that carbonized biomass can be utilized to reduce greenhouse gas emission from the orchard field.

• Journal of the Korean Chemical Society
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• v.33 no.3
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• pp.281-286
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• 1989

The redox properties of benzophydroxamic acid (Hben) and its oxovanadium complex, $VO(Ben)_2$ has been studied by the use of polarograpy and cyclic voltammetry. The radical anions of Hben seem to be generated in acetone. The wave at -0.05V vs. Ag/AgCl electrode might be attributed to the formation of radical anion and the wave at -1.78V vs. Ag/AgCl electrode might be attributed the formation of radical dianion. The $VO(Ben)_2$ exhibits one oxidation wave at + 0.55V and two reduction waves at -0.15V and -1.30V vs. Ag/AgCl electrode; the oxidation is reversible one electron process $(VO(ben)_2 {\rightleftharpoons} VO(ben)^+ + e)$. The reduction wave at -0.15V is quasireversible and is arised from the formation of radical anion,$VO(Ben)_2^-$. The second reduction wave at -1.30V is irreversible and this reduction process produces vanadium(III). This oxygen containing ligand of Hben seems to reduce the stability of + 4 oxidation state of vanadium while the sulfur or nitrogen donor of the ligands stabilize the + 4 oxidation state of vanadium when comparisons are made among several oxovanadium complexes.

• Journal of the Korean Chemical Society
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• v.37 no.8
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• pp.711-716
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• 1993

The mechanism for electrochemical oxidation of natural alkaloid, ${\iota}$-sparteine (SP) was studied in acetonitrile solvent. The cyclic voltammogram of SP shows two irreversible anodic peaks at +0.75 V and +1.45 V vs. Ag/AgCl (0.1M AgNO$_2$ in acetonitrile) electrode. Coulometry reveals that the number of electrons involved in each oxidation peaks is in the range of 1.2∼1.3 respectively. Neutral imine radical was produced by fast deprotonation of SP radical cation formed by oxidation of one nitrogen atom in SP. Two pathways are possible for the reaction of the neutral radical: Due to the disproportionation of the radical, SP and enamine were mainly produced. Also, the 1,2-dehydrosparteinium cation was formed as minor product through the second one electron transfer oxidation of this radical. The (+)-lupanine was produced by treatment of sparteinium cation with potassium hydroxide. We have isolated and confirmed the electrolysis products using IR, GC-MS, UV-Vis, and thin-layer spectroelectrochemical method.

• Korean Journal of Optics and Photonics
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• v.16 no.6
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• pp.535-541
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• 2005

We report on the development of a passively mode-locked near-infrared femtosecond laser with Cr:YAG crystal that operates near room temperature. The laser wavelength could easily be tuned by using only the internal prism pair over 110 nm from 1400 nm to 1510 nm in cw and over about 30 nm in mode-locked operation, respectively Maximum cw output powers of 810 mW were obtained with $1.5 \%$ output coupler for absorbed pump powers of 7.6 W. For compensation of the internal group velocity dispersion, an IR graded prism pair was used. The Cr:YAG laser delivered nearly Fourier-transform limited pulses with a pulse duration as short as 64 fs at 100 MHz repetition rate. In the mode-locked regime, the laser was operating at 1510 nm with a spectral bandwidth of 44 nm. In order to avoid unstable mode-locking and power instabilities, self-built tubes were inserted into the beam path in the resonator and purged with N2 gas. Finally, output powers of the Cr:YAG laser were optimized to 250 mW fer long time stable mode-locked operation.

• Asian Journal of Turfgrass Science
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• v.24 no.1
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• pp.56-61
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• 2010

This study was conducted to evaluate the effect of application of SCB liquid fertilizer produced after slurry composting and biofiltration (SCB) on turfgrass growth in golf course during 6 month period from May to October in 2008. The change of soil properties by applying CF and SCB was unaffected respective treatments. As compared with NF, turf color index of CF, S-1 and S-2 increased by 1.8%, 2.5%, and 3.4%, respectively and chlorophyll content by 13%, 19%, and 25%, respectively. Dry weight of S-1 and S-2 was increased by 15% and 26% than that of CF. As compared with CF, N uptake rate in S-1 and S-2 was increased by 21% and 37%, P uptake rate 57% and 28%, and K uptake rate 16% and 27%, respectively. S-2 showed the best effect for turf color index, chlorophyll content, dry weigh and nutrient uptake rate in creeping bentgrass. These results suggested that an mixed application of SCB and compound fertilizer was improved turf quality and growth of creeping bentgrass by increasing nutrient uptake rate of turfgrass.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.1
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• pp.103-110
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• 2012

The flow field, fuel-air mixing, and behaviors of turbulent flames have been investigated using the large eddy simulation (LES) numerical technique in a premixed swirl combustor equipped with EV double cone burners. Recirculation zones are generated by the swirl burner, and lean premixed flames are formed within a distance of 0.2 m from the tip of the burner. NOx emission of 0.46 ppm is predicted at 1 atm and an air/fuel ratio of 38.7. However, most of the CO generated in a flame front continues to be oxidized as it moves toward the exit, and CO emission of 5.45 ppm is predicted at the exit. The NOx emission can be reduced by decreasing the pressure and air/fuel ratio. The characteristics of NOx emission have been investigated through RANS simulations for various fuel injection types, and it is found thereby that five-lance-hole injection produces the lowest NOx emission rate.

• Membrane Journal
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• v.15 no.4
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• pp.310-319
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• 2005

This paper describes the preliminary study on the development of multi-stage membrane demonstration plant for removal of carbon dioxide from flue gas stream being emitted from LNG boiler in thermal power generation plant. The prerequisite requirement is to design and develop the membrane process producing a $99\%\;CO_2$ with $90\%$ recovery from LNG flue gas of 1,000 $Nm^3$/day. Asymmetric polyethersulfone hollow fiber membranes and membrane modules developed in this laboratory[1] were used in this study. Using the permeation data for the hollow fiber membranes, modelling on the membrane module and multi-stage membrane process was done to meet the requirement condition of the process design. The effects of the operating pressure of feed and permeate side and feed concentration on $CO_2$ purity and recovery were investigated experimentally with the developed hollow fiber modules. These experimental results matched well with theoretical modelling results.