• KCI Concrete Journal
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• v.13 no.1
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• pp.3-9
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• 2001

This research concerns the effect of kaolin as material of cement admixture. which has the advantage of low price and high adaptability. Kaolin, a kind of soil, is well known as a raw material of pottery. which is widely scat-tered on the earth (especially in Korea). This research shows the method and process for activating kaolin to have the properties of a cement admixture through experiment. In the experiments, kaolin is baked in high temperature and then cooled suddenly to be activated. The temperature zone and time span, on which kaolin is activated are examined. The research looks over the effect of the activated kaolin based on several criteria regarding to chemical and physical characteristic of general admixtures. The results of this research are as follows; kaolin start activation at the temperature above 50$0^{\circ}C$ and make ends of activation at the temperature below 95$0^{\circ}C$ and there was little effect by the change of duration. It is concluded that compressive strength can be increased by putting activated kaolin in the concrete and the activated kaolin is good for water resistance and anti-chemical , and that it is effective for protecting the leakage of hazardous article like Cl- and for protecting damage by an organic salt like acid. The activated kaolin of proper temperature and time is effective in compressive strength, salt resistance and acid resistance. The adaptability of activated kaolin as a cement admixture was shown through this research.

• Journal of The Korean Society of Agricultural Engineers
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• v.51 no.1
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• pp.21-26
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• 2009

This study was performed to evaluate the physical and mechanical properties of concrete using waste activated carbon. Materials used were ordinary portlant cement, crushed coarse aggregate, natural fine aggregate, waste activated carbon, and superplasticizer. The substitution ratios of waste activated carbon were 0,1,2,3,4,5,6,7,8,9 and 10%. The unit weight was decreased and water absorption ratio was increased with increasing the waste activated carbon content, respectively. When the substitution ratio of waste activated carbon was 3%, compressive strength, flexural strength and dynamic modulus of elastisity were more higher than that of the ordinary portland cement (OPC), and it was decreased with increasing the waste activated carbon content, respectively. The most effective contents of waste activated carbon was 2% in performance and 4% in practical use Accordingly, waste activated carbon can be used for concrete material.

• Journal of the Korean Society for Heat Treatment
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• v.14 no.3
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• pp.151-154
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• 2001

$TiO_2$ thin film has wide application because of its high capacitanca, reflection, and good transmissivity in visible range. $TiO_2$ thin film can be made by thermal deposition method, reactive evaporation method, activated reactive evaporation(ARE) method. In the case of thermal deposition, the oxygen deficiency can occur because the melting point of Ti is very high. While in the case of reactive evaporation, high density $TiO_2$ can not be made, because reactive gas($O_2$) and evaporated material(Ti) are not fully combined, activated reactive evaporation, $TiO_2$ is easily deposited at lower gas pressure compared with reactive evaporation because the ionized reactive gas is made by plasma. Therefore, activated reactive evaporation is very useful to deposit the material having the high melting point. In this work, we formed $TiO_2$ thin film by activated reactive evaporation method. The surface of $TiO_2$ thin film was analyzed by X-ray photoelectron spectroscopy. The surface morphology which was analyzed by atomic force microscopy(AFM) shows that feature of the film surface is uniform. The dielectric capacitance, withstanding voltage were $600{\mu}F/cm^2$, 0.4V respectively. In further work, we can increase the withstanding voltage by improving the deposition parameter of substrates.

• Applied Chemistry for Engineering
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• v.20 no.4
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• pp.396-401
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• 2009

A micro-spherical activated carbon with meso-pore structure of 52~64% and particle diameter of $2{\sim}10{\mu}m$ was prepared for the improvement electrochemical performance of activated carbon as electrode material for electric double layer capacitor. Resorcinol-formaldehyde resin was used as a carbon source in this preparation. According to electrochemical analysis of EDLC using this activated a carbon with showing effects to reduce charge transfer resistance and to increase rate capability, it was found out that micro-spherical activated carbon could be a good method as well as a material for enhancing the performance of electric double layer capacitor.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.336-337
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• 2005

This study shows the effect of addition of $LiCoO_2$, with different milling time ranging from 0, 30, 200 hours, to the activated carbon electrode. Test cells consisting of activated carbon (100-X%) and $LiCoO_2$ (X%)were made (where X=10, 20, and 40). Test cells with varying concentrations of $LiCoO_2$ which differ in the milling time showed improved specific capacity compare with the cells fabricated using activated carbon alone. The enhanced capacity may be caused due to the addition of $LiCoO_2$ powders at varying concentration. An improved ESR value obtained may be caused by the smaller particle size of $LiCoO_2$. It was concluded that finer the particle size higher will be the efficiency.

• Bulletin of the Korean Chemical Society
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• v.35 no.1
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• pp.103-110
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• 2014

Sisal fiber, an agricultural resource abundantly available in china, has been used as raw material to prepare activated carbon with high surface area and huge pore volume by chemical activation with zinc chloride. The orthogonal test was designed to investigate the influence of zinc chloride concentration, impregnation ratio, activation temperature and activation time on preparation of activated carbon. Scanning electron micrograph, Thermo-gravimetric, $N_2$-adsorption isotherm, mathematical models such as t-plot, H-K equation, D-R equation and BJH methods were used to characterize the properties of the prepared carbons and the activation mechanism was discussed. The results showed that $ZnCl_2$ changed the pyrolysis process of sisal fiber. Characteristics of activated carbon are: BET surface area was $1628m^2/g$, total pore volume was $1.316m^3/g$ and ratio of mesopore volume to total pore volume up to 94.3%. These results suggest that sisal fiber is an attractive source to prepare mesoporous high-capacity activated carbon by chemical activation with zinc chloride.

• Journal of the Korean Ceramic Society
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• v.44 no.11
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• pp.633-638
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• 2007

The setting time of alkali activated slag cement tends to be much faster than ordinary Portland cement, and its compressive strength had been higher from the 1 day but became lower than that of the cement on the 28 days. According to the results of the surface observation, weight loss, compressed strength, and erosion depth tests on the sulphuric acid solution. It has been drawn that alkali activated slag cement has a higher sulphate resistance than ordinary Portland cement, and in particular, the alkali activated slag cement added 5 wt% alumina cement has little deterioration on the sulphuric acid solution. The reason why the alkali activated slag cement has higher sulphate resistance than other hardened cement pastes is that it has no $Ca(OH)_2$ reactive to sulphate ion, and there is little $CaSO_4{\cdot}2H_2O$ production causing volume expansion, unlike other pastes. And it is supposed that $Al(OH)_3$ hydrates with high sulphate resistance, which is produced by adding the alumina cement increases the sulfate resistance.

• Composites Research
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• v.35 no.1
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• pp.1-7
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• 2022

The activated carbon is a very good choice for using as supercapacitor electrode materials. Herein, the flower of Shorea robusta, a bio-waste material was successfully used to synthesize the activated carbons for application as supercapacitor electrode materials. The activated carbon was synthesized through chemical activation process followed by thermal treatment at 700℃ in presence of N₂ atmosphere using KOH, ZnCl₂ and H₃PO₄ as the activating agents. The physicochemical analyses demonstrate that the obtained activated carbons are graphitic in nature and the degree of disorder of the graphitic carbons is changed with the activating agents. The activated carbon obtained from Shorea robusta flower (ACSF-K) electrode shows the specific capacitance of ~610 F g^-1 at 2 A g^-1 current density, which is higher than ACSF-Z (560 F g^-1) and ACSF-H (470 F g^-1) electrode material under the identical current density. The synthesized graphitic carbons also demonstrated good rate capability and high electrochemical stability as supercapacitor electrode.

• Journal of Environmental Science International
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• v.8 no.2
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• pp.221-225
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• 1999

This study was conducted to evaluate the treatment efficiency including reaction kinetics and hydraulic characteristics of food processing wastewater by using an ejector-type aeration system (ETAS) in activated sludge process. The oxygen transfer efficiency in ETAS can be changed in accordance with the depth of reactor. However, the optimum air velocity was found less than 1.82 m/hr at a superficial liquid velocity of 634 m/hr. The ETAS process showed higher organic material removal efficiency than that of the existing activated sludge process under hydraulic detention time 6 to 12 hours. This process, which can maintain MLVSS highly, is able to have high organic material removal efficiency at short HRT and deal with variable organic material loading.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.11a
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• pp.165-170
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• 2009

Since artificial building materials and environmental contamination are getting worse recently, people has been interested in eco-friendly construction. In addition, the problems like Sick Building Syndrome are issued these days. In order to solve these problems, the reuse of building materials and the development of environment-friendly materials are urgently in demand. In this sense, Hwangtoh is in the limelight as the environment-friendly material, and broad studies on it have been in progress. However the reactivity of Hwangtoh is low, and without activation process it is very hard to use it as a building material. This study examined the usability of Hwangtoh as an environmental building material by experimenting the reactivity of inactivated Hwangtoh with Reaction Induction Material.