• Journal of Environmental Science International
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• v.17 no.5
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• pp.493-500
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• 2008

This paper describes the adsorption/desorpton efficiency of a modified activated carbon by irradiated microwave to treat toluene. By employing microwave energy, the regeneration time was considerably shortened compared with conventional thermal heating regeneration. New adsorbent called ACB (Activated Carbon-Bentonite) was prepared from powder activated carbon with mixing bentonite as a binder. Specific surface area, average pore size and total pore volume of ACB were calculated from the nitrogen adsorption/desorption isotherm. The surface of ACB was characterized with scanning electron microscope(SEM). The results showed that the specific surface area, total pore volume, average pore size of ABC was not influenced by regenerating cycle with microwave irradiation. Toluene was adsorbed onto ACB which desorbed by MW irradiation. Absorption capacity of ACB was 0.117 $g_{toluene}/g_{ACB}$. Desorption efficiency of toluene increased as higher microwave output was applied.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.1
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• pp.61-70
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• 2004

Generally, ceramics are very difficult-to-cut materials because of its high strength and hardness. The machining process of ceramics can be characterized by cracking and brittle fracture. In the machining of ceramics, edge chipping and crack propagation are the principal reasons to cause surface integrity deterioration. Such phenomenon can cause not only poor dimensional and geometric accuracy, but also possible failure of the ceramic parts. Ceramics can be machined with traditional method such as grinding and polishing. However, such processes are generally cost-expensive and have low material removal rate. Thus, in this paper, to overcome these problems. BN powder, which gives good cutting property, is added for the fabrication of machinable ceramics by volume of 5,10,15,20,25 and 30%. And, mechanical properties, R-curve behavior and machining tests are carried out to evaluate the machining properties of the manufactured machinable ceramics.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.477-480
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• 2005

In this paper, the concept of sustainability was applied to mechanical design and manufacturing of mobile-phone case. A new evaluation method to find products' good and weak point for sustainability was developed. Two mobile phones were evaluated using the evaluation tool. As a result, electro-magnetic (EM) wave was considered as a harmful factor of the products, and improved front panel was made using nano particles that absorb EM waves. The EM shielding tests revealed that silver nano powders absorbed EM while MWCNT had no effect.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1668-1671
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• 2005

Vulcanized natural rubber was pulverized using a single screw extruder in a non-cryogenic Solid Shear Extrusion process where rubber granulates were subjected to high compressive and shear stresses. The producted particles had diameters ranging from 40 to 1200$\{mu}m$. A principle used in this paper was developed in Russia. The development method for producing a polymeric material powder consists in compressing said material by shearing the material during a pressure increase and cooling. Consecutive breakdown is carried out by shearing the material during the pressure decrease and cooling.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.201-203
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• 1991

T. Kanal et al, were studied the superconducting properties in Bi system by mechanical grinding, in which the authors found that the samples ground degraded from the superconducting phases to nonsuperconducting phases. To obtain more information of the practical application in Bi system with high-Tc phase in this paper, these samples mechanically ground and the high-Tc phase properties of grinding powder samples were investigated.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.317-322
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• 2001

This paper investigates the influence of fine aggregates on bleeding of concrete. According to test results, as water content decreases, crushed sand content increases, fluidity shows decline tendency. As for aggregates kinds, concrete using sea sand shows most fluidity loss among the tested results. Compressive strength gains highly when crushed sand is used. As for bleeding of concrete, bleeding shows decline tendency because of increasing in powder content and filling effect of voids. Bleeding amount is in a decreasing order of magnitude for concretes made with the following aggregates: sea sand, river sand, and crushed sand. Accordingly, crushed sand mixed with river sand and sea sand with certain proportion enable to reduce bleeding and enhance strength.

• Proceedings of the Korea Concrete Institute Conference
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• 1990.04a
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• pp.11-15
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• 1990

Results of an experimental study on the manufacture and the mechanical properties of carbon fiber reinforced fly ash-cement composites are presented in this paper. The carbon fiber reinforced fly ash-cement composites using silica powder and a small amount of Ethylene vinyl acetate emulsion are prepared with carbon fiber, foaming agents and curing conditions. As a result, the manufacturing process technology of carbon fiber reinforced fly ash-cement composites is developed. And the mechanical properties such as compressive, tensile and flexural strengths and drying shrinkage of lightweight carbon fiber reinforced fly ash-cement composites are improved by using a small amount of Ethylene vinyle acetate emulsion. The development and applications of precast products and the design systems of lightweight carbon fiber reinforced fly ash-cement composites are expected in the near future.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.814-817
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• 2004

Deterioration due to de-icer salt occurs in practice in concrete pavement, dike, barrier and similar structure. This paper reports the results of effect of de-icer salt on. durability of concrete structure in winter. To protect concrete structure from damage by de-icer salt in winter, the exposure test was performed using three countermeasures such as increase in design strength upto $350kg/cm^2$, application of ggbf slag powder, and concrete sealer. Of these, the method of increase in design strength upto $350kg/cm^2$ showed better durability for deterioration by de-icer salt.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.556-559
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• 2004

In this Paper, concrete durability, coefficient variation of compressive strength, and hydration heat development characteristics of concrete using different types binder for 2nd Phase Construction in IIA were investigated. The experimental results show that the coefficient variation of compressive strength decreased with the slag cement when compared with the replacement of granulated blast furnace slag powder. And the diffusion coefficient of chloride ion decreased with use of a blended cement when compared with using a only portland cement. Also the type of low heat cement is very suitable to reduce the thermal crack caused by hydration heat development.

• International Journal of Concrete Structures and Materials
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• v.10 no.2
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• pp.249-256
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• 2016

This paper deals with the effects of silica fume content and polymer-binder ratio on the properties of ultrarapid-hardening polymer-modified mortar using silica fume and ethylene-vinyl acetate redispersible polymer powder instead of styrene-butadiene rubber latex to shorten the hardening time. The ultrarapid-hardening polymer-modified mortar was prepared with various silica fume contents and polymer-binder ratios, and tested flexural strength, compressive strength, water absorption, carbonation depth and chloride ion penetration depth. As results, the flexural, compressive and adhesion strengths of the ultrarapid-hardening polymer-modified mortar tended to increase as increasing polymer-binder ratio, and reached the maximums at 4 % of silica fume content. The water absorption, carbonation and chloride ion penetration resistance were improved according to silica fume content and polymer-binder ratio.