• Membrane Journal
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• v.27 no.4
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• pp.319-327
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• 2017

Chitosan/Pebax composite membranes were prepared with 1 : 1, 1 : 2, 1 : 10, 1 : 30 mass ratio of pebax and chitosan. Gas permeation test were carried out under pressure $6kgf/cm^2$, 35, $45^{\circ}C$ and $65^{\circ}C$ at different temperatures. The gas permeability and selectivity ($CO_2/N_2$) of $N_2$ and $CO_2$ for the Chitosan/Pebax composite membranes were investigated. As the amount of Pebax added to chitosan was increased the gas permeability of both $N_2$ and $CO_2$ increased. The selectivity ($CO_2/N_2$) was 6.9~44.3 in the Chitosan/Pebax composite membranes. With the increase of contents of Pebax and the decrease of temperature, the selectivity ($CO_2/N_2$) increased.

• Journal of Environmental Science International
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• v.17 no.8
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• pp.933-941
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• 2008

The formation of $Co_nTiO_{n+2}$ compounds, i.e., $CoTiO_3$ and $CO_2TiO_4$, in a 5wt% $CoO_x/TiO_2$ catalyst after calcination at different temperatures has been characterized via scanning electron microscopy (SEM), Raman and X-ray photoelectron spectroscopy (XPS) measurements to verify our earlier model associated with $CO_3O_4$ nanoparticles present in the catalyst, and laboratory-synthesized $Co_nTiO_{n+2}$ chemicals have been employed to directly measure their activity profiles for CO oxidation at $100^{\circ}C$. SEM measurements with the synthetic $CoTiO_3$ and $CO_2TiO_4$ gave the respective tetragonal and rhombohedral morphology structures, in good agreement with the earlier XRD results. Weak Raman peaks at 239, 267 and 336 $cm^{-1}$ appeared on 5wt% $CoO_x/TiO_2$ after calcination at $570^{\circ}C$ but not on the catalyst calcined at $450^{\circ}C$, and these peaks were observed for the $Co_nTiO_{n+2}$ compounds, particularly $CoTiO_3$. All samples of the two cobalt titanate possessed O ls XPS spectra comprised of strong peaks at $530.0{\pm}0.1$ eV with a shoulder at a 532.2-eV binding energy. The O ls structure at binding energies near 530.0 eV was shown for a sample of 5 wt% $CoO_x/TiO_2$, irrespective to calcination temperature. The noticeable difference between the catalyst calcined at 450 and $570^{\circ}C$ is the 532.2 eV shoulder which was indicative of the formation of the $Co_nTiO_{n+2}$ compounds in the catalyst. No long-life activity maintenance of the synthetic $Co_nTiO_{n+2}$ compounds for CO oxidation at $100^{\circ}C$ was a good vehicle to strongly sup port the reason why the supported $CoO_x$ catalyst after calcination at $570^{\circ}C$ had been practically inactive for the oxidation reaction in our previous study; consequently, the earlier proposed model for the $CO_3O_4$ nanoparticles existing with the catalyst following calcination at different temperatures is very consistent with the characterization results and activity measurements with the cobalt titanates.

• The Korean Journal of Pesticide Science
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• v.11 no.1
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• pp.8-17
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• 2007

Three-dimensional quantitative structure-activity relationships (3D-QSARs) on the fungicidal activity against damping-off (Pythium ultimum) with N-phenylbenzenesulfonamide and N-phenyl-2-thienylsulfonamide analogues (1-34) were studied quantitatively using CoMFA (comparative molecular field analysis) and CoMSIA (comparative molecular similarity indeces analysis) methodologies. On the whole, the statistical qualities of CoMSIA models with field fit alignment (FF1-FF5) were slightly higher than that of atom based fit alignment (AF1-AF5) but, the deviations of statistical quality between two alignments in case of CoMFA models were slightly lower. The statistical results of CoMFA and CoMSIA model showed that the optimized CoMSIA model (FF1: $r_{cv.}^2\;(q^2)=0.674$ & $r_{ncv.}^2=0.964$) for damping-off is better predictability and fitness for fungicidal activities than CoMFA model (AF5: $r_{cv.}^2\;(q^2)=0.616$ & $r_{ncv.}^2=0.930$). The fungicidal activities according to the information of the CoMSIA (FF1) model were dependence upon the electrostatic and hydrophobic field of the N-phenylbenzene sulfonamide analogues. Therefore, from the results of graphical analyses on the contour maps with CoMSIA (FF3) model, it is expected that the characters of R4-substituent on the N-phenyl ring as hydrophobic and hydrogen bond acceptor will be contributed to the fungicidal activity against damping-off.

• Korean Journal of Plant Resources
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• v.11 no.2
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• pp.119-123
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• 1998

Effects of elevated CO2 and temperature on nitrogen (N) uptake , leaf N concentration, N partitioning , N use efficiency (NUE) and grain yield of pot and field grown rice (Oryza sativa. L.cv. Chukwangbyeo) under canopy-like conditions were studied over three years. Rice plants were grown in pots and in the field in temperature gradient chambers containing either ambient(350ppm) or elevated CO2 concentrations (690 or 650ppm) in conbination with either four or seven temperature regimes ranging form ambient temperature(AT) to AT plus 3$^{\circ}C$. There were three N supplies 94g or 6g m-2 to 20g or 48g m-2.Elevated CO2 increased N uptake in field-grown rice ; the magnitude of this effect was thelargest (+15%) at the highest N level. However, in pot-grown rice, N uptake was suppressed with the effect was the largest at high N levels. Leaf N concentration declined at elevated CO2 mainly due to a decrease in N partitiioning to the leaf blades. Air temperature had little effect on the N parameters mentioned previously, wherease NUE for spikelet production declined rapidly with increased temperature irrespective of CO2 concentration. The response of the biomass to elevated CO2 varied with N level, with the greatest response at 20g N m-2 (+30%) . At AT, where high temperature-induced sterility was generally not observed, elevated CO2 increased yield. However, the magnitude of this effect varied greatly (2-39%) with N level, and was mainly dependent on the magnitude of the increase in spikelet number.

• Korean Journal of Materials Research
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• v.16 no.1
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• pp.30-36
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• 2006

A novel method was proposed to grow an epitaxial $CoSi_2$ on (100)Si substrate. A $CoN_x$ interlayer was deposited by reactive sputtering of Co in an Ar+$N_2$ flow. From the Ti/Co/$CoN_x$/Si structure, a uniform and thin $CoSi_2$ layer was epitaxially grown on (100)Si by annealing above $700^{\circ}C$. Two amorphous layers were found at the $CoN_x$/Si interface, where the top layer has a silicon nitride (Si-N) bonding state with some Co content and the bottom layer has a Co-Si intermixing state. The SiNx amorphous layer seems to play a critical role of suppressing the diffusion of Co into Si substrate for the direct formation of epitaxial $CoSi_2$.

• Journal of the Korean Society of Combustion
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• v.7 no.4
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• pp.29-35
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• 2002

[$CO_2$] is a well-known greenhouse gas, which is the major source of global warming. Many researchers have studied to reduce $CO_2$ emission in combustion processes. The central method of low $CO_2$ emission is Oxygen/CxHy combustion. Theoretically Oxygen/CxHy combustion only produces $CO_2\;and\;H_2O$ and allows convenient recovery of $CO_2$. The combustion characteristics, flame stability, composition in the flame zone and temperature profile were studied experimentally for various compositions of oxidant by substituting $CO_2\;for\;N_2$ with the constant $O_2$ concentration. Results showed that flame became unstable due to the high heat capacity, low transport rate and strong radiation effect of $CO_2$ in comparison with those of $N_2$. The reaction zone was quenched and broadened, as the ratio of $CO_2\;to\;N_2$ was increased. The emission of NOx in flue gas decreased due to the decreased temperature of the reaction zone. As the conversion ratio of $CO_2\;to\;N_2$ was increased, the emission of CO and the higher temperature zone increased due to decrease of reaction rate by the a quenching effect.

• Korean Journal of Agricultural and Forest Meteorology
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• v.20 no.4
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• pp.386-396
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• 2018

Cropland is sources of atmospheric nitrous oxide ($N_2O$) and carbon dioxide ($CO_2$). However, the contribution of the fallow season to emission of these gases has rarely been determined. In this study, a field experiment encompassing three treatments was conducted to determine efflux of $N_2O$ and $CO_2$ in cropland during fallow season. The treatments were hairy vetch (H.V.), rye and control (Con.). The H.V. and rye were sown in middle October and early November, respectively. The soil $N_2O$ efflux among all three treatments in the fallow season (November-April) were $0.014-2.956mg\;N_2O\;m^{-2}{\cdot}d^{-1}$. The cumulative $N_2O$ emissions were $104.4mg\;N_2O\;m^{-2}$ for Con., $85.8mg\;N_2O\;m^{-2}$ for H.V. and $85.0mg\;N_2O\;m^{-2}$ for Rye during the fallow season. The highest $N_2O$ emissions occurred in Con., while H.V. and Rye emissions were similar. Cumulative $CO_2$ emissions were $293.1g\;CO_2\;m^{-2}$ for Con., $242.2g\;CO_2\;m^{-2}$ for H.V., $275.2g\;CO_2\;m^{-2}$ for Rye during fallow season. This study showed that soil $N_2O$ and $CO_2$ average daily emission during fallow season were 28.3% and 27.4%, respectively of the growing season. Our results indicate that $CO_2$ and $N_2O$ emissions from agricultural systems continue throughout the fallow season.

• Applied Chemistry for Engineering
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• v.32 no.4
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• pp.431-441
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• 2021

In this study, PEBAX/GO-PEI and PEBAX/ZIF-8@GO-PEI composite membranes were prepared by varying the contents of GO and ZIF-8@GO in PEBAX, and also the gas permeation characteristics of N₂ and CO₂ was studied. Overall, the N₂ and CO₂ permeability of the PEBAX/GO-PEI composite membrane decreased as the GO content increased, and the CO₂/N₂ selectivity slightly increased. In the case of PEBAX/ZIF-8@GO-PEI composite membrane, the permeability of N₂ decreased, but CO₂ increased to 1 wt% of ZIF-8@GO and then decreased in the content thereafter. The CO₂/N₂ selectivity at 1 wt% of ZIF-8@GO was 92.3, showing the highest selectivity. This is thought to be due to the greatest effect of GO and ZIF-8 with good affinity for CO₂ alongside the effect of porosity ZIF-8 while improving compatibility with PEBAX and dispersing evenly. In addition, PEBAX/ZIF-8@GO-PEI composite membrane improved both CO₂ permeability and CO₂/N₂ selectivity than those of the PEBAX-PEI and PEBAX/GO-PEI membranes, except for ZIF-8@GO 5 wt%. The result was close to the Robeson upper bound.

• Mass Spectrometry Letters
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• v.10 no.1
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• pp.27-31
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• 2019

In this article, the properties of ${CO_2}^+(CO_2)_n$ clusters in a Paul ion trap have been investigated using mass-selective instability mode which conducted by chosen precursor ions, mainly $Ar^+$ and ${CO_2}^+$ produced by a mixture of Ar and $CO_2$. Exposure of ${CO_2}^+$ ions to $CO_2$ molecules, lead to the formation of ${CO_2}^+(CO_2)_n$ clusters. Here, Ar gas react as a buffer gas and lead to form ${CO_2}^+(CO_2)_n$ cluster by collisional effect.

• Proceedings of the Membrane Society of Korea Conference
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• 1998.10a
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• pp.46-49
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• 1998

1. 서론 및 이론적 배경 : 지구 온난화에 의한 생태계 변화의 위해 문제가 대두됨에 따라 온난화의 주요인인 이산화탄소를 발생원으로부터 분리, 회수하는 기술에 대한 관심이 고조되고 있다. 최근에는 이러한 기술 중에서 에너지가 적게 소요되며 환경 친화적인 분리막 공정에 의한 CO$_2$의 효율적인 분리, 회수법이 하나의 대안으로 연구되고 있다. 분리막 기술 중 함침액막법은 고분자막의 장점을 이용하면서도 투과도를 크게 향상시킬 수 있는 장점이 있어 최근에 액막을 이용한 CO$_2$/N$_2$혼합가스의 분리, 회수연구도 수행되고 있다. 순수한 물에 대한 CO$_2$의 용해도는 8x10$^{-6}$/cmHg이며, N$_2$는 1.55x10$^{-7}$/cmHg 로서 대략 50배 정도의 용해도 차를 보이고 있는데 이러한 물에 대한 기체의 높은 용해도 차를 이용하면 효과적으로 CO$_2$를 분리,회수할 수 있을 것으로 기대된다. 본 연구에서는 이러한 물을 함침한 액막을 이용하여 CO$_2$/N$_2$를 분리하였으며 혼합기체의 조성, 기체의 압력 등의 변수가 액막에 의한 CO$_2$의 분리에 미치는 영향을 조사하였다.