• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.05a
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• pp.230-231
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• 2017

The addition of a limestone filler(LF) to fill into the voids between cement and aggregate particles can reduce the cementitious paste volume. This paper aim to evaluate the influence of LF contents on the hydration kinetics and compressive strength. Hydration kinetics were evaluate using heat of hydration, ignition loss and thermal analysis. The heat of hydration was measured using Isothermal Calorimetry. The degree of hydration was measured using ignition loss. Hydration product analysis was carried out by Thermal Gravimetric and Differential Thermal Analysis. The results show that the addition of LF reduces not only the initial setting time and heat of hydration peak, also degree of hydration and rate of strength development at early age increase with the addition of LF. It can be concluded the LF fills the pore between cement particles due to formation of carboaluminate, which may accelerate the setting of cement pastes.

• Journal of the Korean institute of surface engineering
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• v.1 no.1
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• pp.14.1-18
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• 1967

The characteristics of sulfuric acid anodized layer was studied under various Conbitions, acid concentration : 5-20%, temperature : 5-25$^{\circ}C$, bath voltate : 16 volts , bath agitain : mech agitation : mechanical . The Al+++ ion increase in anodizing baty, the film thickness under microscope, the comparative porosity and the thickness were determined. It was found that film thickness and the porosithy which are the main factors of determining andoized layet quality, rule the corrosing and abrasiion tesistance of the film, and that the porosity is increasing in the outerlayer. The formation mechanism was assumed as follows : The film thickness -increase is due to OH_ ion diffusion into compact non-conductive layer and Al+ + OH_ \longrightarrowAl(OH), Al(OH)+ + OH_ \longrightarrowAl(OH)+$_2$ , Al(OH)+$_2$ + OH_ \longrightarrowAl(OH)$_3$., the strong adhesion force is alse due to Al(OH) or Al(OH)$_2$ in transtion layer. And the pore-nucleation is produced by volume change between Al and Al$_2$O$_3$ and activated H$_2$O gas created by large reaction heat of Al+(x) +OH_ \longrightarrowAl(OH)x.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1996.11a
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• pp.131-139
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• 1996

To quantitatively investigate the effects of manure compost on the soil and water environment including ground water the elution patterns of anions and hydraulic conductivity wore estimated with four different depth(15, 30, 45 60cm) and four variable ratio of compost treatment(0, 2, 4, 6%) through soil column test. 1. There were over 95% of elution of chloride and nitrate within 0.1 pore volume(PV), and sulfate within 0.2 PV. With 2 ton/10a of cow manure compost treatment recommended total 40 kg/10a of anions added was recovered as effluent at the amount of 17kg chloride, 5.4kg nitrate, and 13.2kg sulfate, respectively However, phosphate rarely recovered in the effluent due to the strong affinity for sorption sites in soils. 2. In multi-layered soil column the maximum peaks of each anion eluted were retardated with increasing soil depth and the amount of organic matter(OM) treatment. 3. With increasing OM up to 2% the saturated hydraulic conductivity(SHC) was greatly decreased, but the slight decrease in SHC was found by addition of OM greater than 4％. In multi-layered soil column SHC was more effected by the lower SHV layer than by that of the higher.

• Applied Chemistry for Engineering
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• v.28 no.1
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• pp.8-16
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• 2017

The importance of the biomass-based activated carbon as an adsorbent has been reviewed with emphasizing on the application in the fields of energy storage and environmental related problems. It is clear from the literature survey that beside surface area and pore volume, surface chemistry also plays important role in determining their usage in various field. The capacities of biomass-based activated carbon can be increased depending upon the choice of the biomass used and the pathway taken for their activation and hence they can be tailored for various applications. Accordingly, this review summarizes the role of biomass based activated carbon in different applications.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.819-835
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• 2009

In order to investigate the field application of selected stabilization methods(cover soil method, surface and total interval treatment of embankment method) on rice paddies contaminated by heavy metals, column test was carried out with heavy metal-contaminated soils collected from rice paddies around abandoned mine site. Columns were made by acrylic and filled with untreated soil, treated soil mixed with amendments(lime stone and steel refining slag) and uncontaminated cover soil according to the design report. Distilled water was discharged into the columns with the velocity of 1 pore volume/day. During test, pH, EC, and heavy metal concentration were measured in the regular term. The column test result showed that the selected stabilization methods were effective remediation method to stabilize heavy metals in paddy soils, but it was also expected that application of surface treatment methods was required the careful observation on pH variation due to the lowest increment.

• Carbon letters
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• v.6 no.2
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• pp.89-95
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• 2005

Crushed peach stone shells were impregnated with $H_3PO_4$ of increasing concentrations (30-70%) followed by heat treatment at 773 K for 3 h. Produced carbons (ACs) were characterized by $N_2$ adsorption at 77 K using the BET-equation and the ${\alpha}$-method. High surface area microporous ACs were obtained, with enhanced internal pore volume, as function of % $H_3PO_4$. Adsorption isotherms from aqueous solution were determined for methylene blue (MB) and p-nitrophenol (PNP), as representatives for dye and phenolics pollutant molecules. Application of the Langmuir model proved the high limiting capacity towards both solute molecules, MB was uptaken in increasing amounts as function of $H_3PO_4$ concentration and generated porosity. High removal of PNP was almost the same irrespective of porosity characteristics. Competitive adsorption of $H_2O$ molecules on the hydrophilic carbon surface seems to partially reduce the available area to the PNP molecules. Application of the pseudo-second order law described well the fast adsorption (${\leq}$ 120 min) at two initial dye concentrations.

• Bulletin of the Korean Chemical Society
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• v.31 no.11
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• pp.3221-3224
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• 2010

This study investigates the requirements of lithium-air cathodes, which directly influence discharge capacity. The cathodes of Li-air cell are made by using five different carbon materials, such as Ketjen black EC600JD, Super P, Ketjen black EC300JD, Denka black, and Ensaco 250G. The Ketjen black EC600JD provides discharge capacity of 2600 mAh/g per carbon weight, while that of Ensaco 250G shows only 579 mAh/g. To figure out the differences of discharge capacity from carbon materials, their surface area and pore volume are analyzed. These are found out to be the critical factors in determining discharge capacity. Furthermore, carbon loading on Ni foam and amounts of electrolyte are significant factors that affect discharge capacity. In order to investigate catalyst effect, electrolytic manganese dioxide (EMD) is incorporated and delivered 4307 mAh/g per carbon weight. This infers that EMD facilitates to break $O_2$ interactions and leads to enhance discharge capacity.

• Proceedings of the Membrane Society of Korea Conference
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• 1995.04a
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• pp.11-15
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• 1995

Polysulfone (PS) membranes were prepared by the phase inversion process using water or isopropanol as nonsolvent. The Flory-Huggins theory for a ternary system nonsolvent/solvent/polymer is applied to describe the thermodynamic equilibria of the components. The calculated ternary phase equilibria show that demixing of a PS binary solution with n-methylpyrrolidone (NMP) will be fast in a water coagulation bath and will be delayed in an isopropanol bath. The prepared membranes were characterized by SEM, gas adsorption-desorption measurement, and permeability test. The membrane, which is precipitated by fast demixing in a water bath, has nodular structures in the skin region and includes finger-like cavities in the sublayer. The membrane coagulated by isopropanol has a very dense and thick skin structure, which is formed by delayed demixing. The membrane coagulated by isopropanol showed considerably lower pore volume and surface area compared to that observed with water coagulation method. With dimethylformamide (DMF) as solvent and 2-3 wt% of water, the solution can show the liquid-liquid phase separation due to agglomation of the polymer-lean phase from the homogeneous solution. The membranes, which were coagulated near an equilibrium state, show the large (micron size) round pores in the whole membranes. The pores do not contribute the permeation characteristics.

• Microbiology and Biotechnology Letters
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• v.42 no.3
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• pp.232-237
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• 2014

We investigated the effects of silica gels on the reduction of the crystallization time for the purification of vancomycin. The shortest crystallization time for vancomycin was obtained when silica gel with a pore diameter of $40-60{\AA}$ and with a particle diameter of 230-400 mesh was used as the material. The use of silica gel as a surface area increasing material dramatically reduced the crystallization time four fold (6 h) when compared with the results where the surface area had not been similarly increased. In addition, the crystal size of vancomycin was decreased with the addition of silica gel. This improved crystallization process has a significant effect on the convenience and feasibility of the purification step for vancomycin.

• Bulletin of the Korean Chemical Society
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• v.25 no.8
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• pp.1189-1194
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• 2004

The adsorption isotherms of N2 onto the metallic silver treated activated carbon fiber samples after acid treatment are Type I with a small amount of capillary condensation hysteresis. Increasing amount of acid treatment leads to a decrease in SBETs and external surface area. But, micropore volume and average pore diameter are presented in constant regular values with increasing amount of sulfuric acid treatment. SEM observes the surface morphology and crystal grown state of metal on the fiber surface. The results of EDX of Ag-activated carbon fiber pre-treated with acid show the spectra corresponding to almost all samples rich in silver with increasing the amount of acid treated. The FT-IR spectra of Ag-activated carbon fiber show that the acid pre-treatment is consequently associated with the homogeneous dispersion of metal with the increased surface acidity of the activated carbon fiber. The type and quality of oxygen groups are determined with Boehm titration method. From the those results, a positive influence of the acidic groups on the carbon fiber surface by acid treatment is also demonstrated by an increase in the contents of metallic silver with increasing of acidic groups.