• Journal of Korean Society of Water and Wastewater
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• v.30 no.4
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• pp.391-399
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• 2016

In this study, carbon dioxide ($CO_2$) was used as an inhibitor of scale production on the surface of RO membrane. In order to compare the effects of $CO_2$ injection on scale production, four RO modules: 1) without $CO_2$ injection and anti-scalant (RO module #1), 2) with only $CO_2$ injection (RO module #2), 3) with only anti-scalant (RO module #3), 4) with both $CO_2$ injection and anti-scalant (RO module #4), were operated for 60 days under constant flux mode. The trans-membrane pressure (TMP) was observed to decrease significantly in RO modules with $CO_2$ injection as compared with the other RO modules. When the feed water pH was controlled at 5.0 by injecting $CO_2$, the maximum TMP in RO modules #2 and #4 was founded to decrease by 42 and 40%, respectively. Moreover, the $Ca^{2+}$ concentration in the concentrate was 20mg/L lower in RO modules without $CO_2$ injection which is attributed to the scale formation on the surface of the RO membranes. The SEM-EDS analysis further showed a serious fouled RO membrane surface in RO modules #1 and #3.

• Journal of Environmental Science International
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• v.9 no.4
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• pp.311-318
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• 2000

To improve $CO_2$pemselectivity, a modified silica membrane was prepared by chemical vapor deposition with tetraethoxysilane(TEOS)-ethanol-water, and TEOS-ethanol-water-HCI solution at 300-$600^{\circ}C$. The silica was effectively deposited in the mesopores of a ${\gamma}$-alumina film coated on a porous $\alpha$-alumina tube by evacuating the reactants through the porous wall. In this membrane, $CO_2$interacts, to some extent, with the pore wall, and $CO_2$/$N_2$selectivity then exceeds the value of the Knudsen diffusion mechanism, while the membrane derived from TEOS alone has no $CO_2$selectivity. The silica membrane prepared from TEOS-ethanol-water-HCI solution showed that $CO_2$permeance was $2.5$\times$10^{-7}mol/s^{-1}.m^{-2}.Pa^{-1} at 30{\circ}C$ and $CO_2$/$N_2$selectivity was approximately 3. The $CO_2$permeance and selectivity was improved by enlarging the surface diffusion with modification of chemical affinity of the silica pores.

• Laser Solutions
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• v.2 no.2
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• pp.42-51
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• 1999

This study has been performed to investigate into some effects of the output power and traverse speed of laser beam on the microstructures, hardness and fatigue resistance of the ductile iron surface-hardened by $CO_2$ laser defocussed beam. Optical micrographs have shown that with increasing the output power and decreasing the traverse speed, the martensite was coarsened and some retained austenite were appeared in ductile iron. The microstructures of hardening zone were composed of bull's eye and some nodular graphite dissolved structures by the effect of self quenching. Fatigue fracture characteristics of ductile iron have appeared in the high stress and low stress ranges. The fracture initiated at nodular graphites in the surface hardened layer due to the stress concentration caused by a notch effect. The interior graphite nodules were broken away or popped out during crack propagation. Fatigue test has shown that values of fatigue strength considerably increased with increasing output power at a given traverse speed.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.1
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• pp.31-37
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• 2011

Recently, the technology of surface treatment is being more important which affects the material cost reduction and substitution to the expensive material. The material used for the mechanical processing should have not only high intensity, but also strength toughness, wear resistance and corrosion resistance. In order to increase the durability and have better quality of the parts using such kind of tooling material, various kinds of research of the surface hardening through many kinds of heat resources is being done and practically applied. In this study, the characteristics of hardening surface zone for high strength of the press die material through laser beam irradiation are researched. In this study, it is experimentally observed by the status of the surface morphology, tensile strength, the hardness distribution of the base metal and wear condition by the surface hardness pattern by the laser beam based on the process parameters of $CO_2$ laser by using SM45C and STD11 used for press tool. Through this research, the characteristics of surface hardened zone for high strength of the thin metal by laser beam irradiation is done.

• Carbon letters
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• v.12 no.4
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• pp.236-242
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• 2011

The oxyfluorination effects of activated carbon nanofibers (OFACFs) were investigated for $CO_2$ storage. Electrospun CFs were prepared from a polyacrylonitrile/N,N-dimethylformamide solution via electrospinning and heat treatment. The electrospun CFs were chemically activated in order to generate the pore structure, and then oxyfluorination was used to modify the surface. The samples were labeled CF (electrospun CF), ACF (activated CF), OFACF-1 ($O_2:F_2$ = 7:3), OFACF-2 ($O_2:F_2$ = 5:5) and OFACF-3 ($O_2:F_2$ = 3:7). The functional group of OFACFs was investigated using X-ray photoelectron spectroscopy analysis. The C-F bonds formed on surface of ACFs. The intensities of the C-O peaks increased after oxyfluorination and increased the oxygen content in the reaction gas. The specific surface area, pore volume and pore size of OFACFs were calculated by the Brunauer-Emmett-Teller and density functional theory equation. Through the $N_2$ adsorption isotherm, the specific surface area and pore volume slightly decreased as a result of oxyfluorination treatment. Nevertheless, the $CO_2$ adsorption efficiency of oxyfluorinated ACF improved around 16 wt% due to the semi-ionic interaction effect of surface modificated oxygen functional groups and $CO_2$ molecules.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.6 no.4
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• pp.640-647
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• 1996

It has been found that an white precipitates at the inside surface is a common characteristics of soda-lime-silica glasses which have not undergone special surface treatments during hot weather season. In this study, the white deposits were examed using by solution method, surface analysis etc., and the dependence of weathering on the atmospheric condition was also investigated. As a results, the white precipitates on the glass surface was discorved as carbonates like $Na_2CO_3{\cdot}H_2O,CaCO_3$. Coming to atmosphere-dependence, it was shown that the glass made and stored at sea shore province had 3 times much severe weathering than that at land province.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.219.2-219.2
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• 2011

The oxyfluorination effects of electrospun carbon nanofibers (OFACFs) were investigated for $CO_2$ storage. Carbon nanofibers were prepared form poly acrylonitrile / N,N-dimethylformamide solution through electrospinning method and heat treatment. Chemical activation of carbon nanofibers were carried out in order to improve the pore structure. And the surface modification of activated carbon nanofibers was conducted by oxyfluorination to improve the $CO_2$ storage on effect of introduced functional groups. The samples were labeled CF (electrospun carbon nanofiber), ACF (activated carbon nanofibers), OFACF-1 ($F_2:O_2$ = 3:7), OFACF-2 ($F_2:O_2$ = 5:5) and OFACF-3 ($F_2:O_2$ = 7:3). The functional group of OFACFs was investigated by x-ray photoelectron spectroscopy analysis. The specific surface area, pore volume and pore size of OFACFs were calculated and pore shape was estimated by the BET equation. Through the adsorption isotherm, the specific surface area and pore volume significantly decreased by oxyfluorination.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.158-161
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• 2003

To develop an effective adsorbent for radio active Carbon Dioxide, $^14CO_2$, which is discharged to nearby atmosphere from nuclear power plants of CANDU type, we made some preliminary adsorbents and tested their abilities of $CO_2$ removal. The chemical agents used was LiOH and we supported or impregnated it on the surface or the internal volume of activated Carbon(GW-H). The physical and chemical properties of various adsorbents were measured using methods such as XRD, BET. SEM images were taken to investigate the change of surface morphology of the adsorbents. Finally, amount of $CO_2$ adsorption of them were verified under specific conditions. We found that mechanical mixing of LiOH and activated Carbon showed the maximum $CO_2$ removal ability, while surface activation of activated Carbon by Nitric Acid-treatment enhanced its $CO_2$ removal efficiency to some degree.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.498-499
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• 2007

In this paper, we report on a study of the electrode/electrolyte interfaces of MCMB/$LiCoO_2$ cell using Ion-chromatography. The cells for the experiments were preconditioned by cycling three times and stabilized at OCV of 3.0V 4.35V and 4.5V. The stabilized cathode electrode was used for surface characterization investigations. Concerning the $LiCoO_2$/electrolyte interfaces, the result obtained have shown the presence of $F^-\;and\;CO_3^{2-}$ on the surface of cathode electrode as well as increasing the concentration of ions as cell voltage increase.

• Journal of Fisheries and Marine Sciences Education
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• v.25 no.3
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• pp.705-715
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• 2013

This Paper presented the reduction methods of $CO_2$ emission from ships during voyage. In order to decrease $CO_2$ emission during voyage the equation was established and conducted the study about the relationship between ship speed, the propulsive efficiency and its $CO_2$ production. The results obtained from the examinations are as follows : 1. $CO_2$ emission from sailing ships can be decreased by reducing specific fuel oil consumption of main diesel engine, coefficient of total resistance and ship speed and also by increasing propeller efficiency. 2. Diesel-electric propulsion system is more effective than diesel-mechanical system to decrease the level of $CO_2$ emission during long voyage. 3. Good condition of ship's hull surface, rudder and propeller's surface can decrease the quantity of fuel oil and $CO_2$ emission by reducing the resistance of ship that can rise the propeller efficiency 4. $CO_2$ emitted from ships can be decreased in a global scale by giving attention to the synthetic transport efficiency.