• Proceedings of the Korea Concrete Institute Conference
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• 1998.04a
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• pp.147-152
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• 1998

This study is to investigate the application of concrete with crushed sand on site. As a result, it is showed that the combined sand mixed with sea sand is very desirable for obtaining workability and strength of concrete, and the optimal replacement percentage of crushed sand is 50% with sea sand. After all, the crushed sand could be sufficiently used as a fine aggregate for concrete in the aspect of economical efficiency and quality, but the particle shape and microsand passing No.200 sieve should be firstly improved for increasing workability of concrete on site.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2000.10a
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• pp.431-437
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• 2000

The aim of the work described in this paper is to develope a pavement method for farm road. To this ends, a series of material test are conducted on in-situ soil which was mixed additives-coarse aggregate, polypropylene fiber, excellent soil compound etc. With the laboratory test results, in-situ pavement test was conducted during two years. The serious problem of the pavement is not appeared up to this time. And the measurement of field data is continued presently. The majority merits of this pavement method is low cost and using environmental materials.

• Magazine of RCR
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• v.13 no.4
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• pp.33-41
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• 2018

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1569-1571
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• 1996

The role of ESR spectroscopy in the characterization of functional LB films is discussed. Optical absorption were performed on LB films of binary mixtures of three kinds of merocyanine dyes where DS and 6Me-DS form J-like aggregates but not DO in single component films. The observed optical absorption spectra of mixed films were markedly dependant on the combination of dyes. We found the formation of J-aggregates in a mixed merocyanine dyes containing a non J-aggregate forming dye DO, in a single component case. In structural studios, ESR is of particular important in the analysis of molecular orientation of LB films. Development of new functional LB films may provide more cases where ESR spectroscopy will clarify the nature of such films.

• Journal of Communications and Networks
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• v.17 no.5
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• pp.473-481
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• 2015

In this study, we propose a clustering algorithm to enhance the performance of wireless sensor and actuator networks (WSANs). In each cluster, a multi-level hierarchical structure can be applied to reduce energy consumption. In addition to the cluster head, some nodes can be selected as intermediate nodes (INs). Each IN manages a subcluster that includes its neighbors. INs aggregate data from members in its subcluster, then send them to the cluster head. The selection of intermediate nodes aiming to optimize energy consumption can be considered high computational complexity mixed-integer linear programming. Therefore, a heuristic lowest energy path searching algorithm is proposed to reduce computational time. Moreover, a channel assignment scheme for subclusters is proposed to minimize interference between neighboring subclusters, thereby increasing aggregated throughput. Simulation results confirm that the proposed scheme can prolong network lifetime in WSANs.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.04a
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• pp.241-247
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• 1997

Reinforced concrete is in general known as high durability construction material under normal enviroments due to strong alkalinity of cement. Marine and harbour concrete as well as concrete mixed with seasand for fine aggregate are exposed to detrimental saltwater wich cause to accel-eate corrosion of reinforcing steel in concrete. If corrosion resistance of concrete gets to weaken due to carbonation and crack in cover concrete, concrete durability rapidly decrease by corrosion of reinforcement steel embedded in concrete. This research is to investigate basic physical properties of various corrosion inhibitors and to evaluate their corrosion resistance in concrete mixed with seasand. The object of this study is develop appropriate corrosion protection systems so as to enhance the durability of concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.04a
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• pp.210-219
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• 1997

This research which lays emphasis on ready mixed concrete standard 25-210~240kgf/$\textrm{cm}^2$ shows the influence caused by the ratio of ingredients of superplasticized concrete, and the flowing and strength development of mortar and concrete according to the ratio of ingredients. This research shows that flowability, compactability, and segregation resistivity are the best condition under the following ratio of ingredients: fly ash 30%, unit binders 490~510kg/$\textrm{m}^3$, unit weight of water 184~194kg/$\textrm{m}^3$, fine aggregate ratio 49~51%, and superplasticizer 1.1~1.5%. Following this ratio of ingredients, the reinforced concrete structures to need design strength 25-210~240kgf/$\textrm{cm}^2$ can apply to complicated constructions.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.04a
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• pp.154-155
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• 2022

In this study, propose a plan to efficiently utilize CGS, a by-product generated from IGCC, as a mixed fine aggregate for concrete. The effect of the premixed cement types and CGS replacement rate on the overall characteristics and length change rate of concrete was analyzed. As a result of the analysis, the effect of CGS was found to be insignificant, and the effect of cement was found to be dominant.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.78-79
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• 2021

In this study, the fluidity and compressive strength properties of concrete according to the mixing ratio of mixed slag aggregates were compared as part of research to alleviate the aggregate supply problem and improve environmental pollution by utilizing industrial by-products.

• Journal of the Korean GEO-environmental Society
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• v.9 no.5
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• pp.5-13
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• 2008

In this study, It was carried out to evaluate the feasibility of recycled crushed concrete as aggregate used cement mortar replace sand and to investigate engineering properties of recycled aggregate for hazardous waste solidification. The compressive strength of cement mortar replaced 5-15% (wt.) recycled aggregate was over $163kgf/cm^2$ which is the standard of first grade concrete block class C. And cement mortar was examined to evaluate the stability by leaching test. Cu, Cd, Pb, Cr, and As as the heavy metals were proved very stable but mercury (Hg) was leached high concentration because it was simply tied to the cement surface. We investigated the crystal structures of cement mortar and they had shown the peaks of $Ca(OH)_2$, ettringite, and CSH (calcium silicate hydrate). As the result, the longer curing time, the higher CSH peak that means to increase compressive strength and the cement mortar was more stable. Therefore it was shown that it may be possible to apply hazardous waste solidification using recycled aggregate, fly ash and sewage sludge ash.