• Proceedings of the Korea Concrete Institute Conference
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• 1998.10c
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• pp.203-206
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• 1998

In reinforced concrete carbonation of concrete leads to depassivation of the reinforcement, and hence to initiation of corrosion. As a result of carbonation accelerating experiment with using effect of wet-dry cycle and 15% concentration of CO ₂, the carbonation rate shows very distinct difference according to W/C ratio. OPC-40 estimated no carbonation depth, whereas OPC-60 estimated rapidly the carbonation rate. The comparative analysis of the carbonation rate accelerating depends on different kinds of cement shows fastest FAC-20. Also, highly W/C ratio's concrete shows low half-cell potential value and fast corrosion rate. During period for 14 weeks. corrosion rate was not severe. So, it can be concluded that only carbonation attack on concrete doesn't severly deteriorated except very poor qualitified concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10c
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• pp.211-216
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• 1998

Recently the shortage of good aggregate has encouraged the use of sea sand in construction field, and the corrosion damage of the reinforced steel in concrete structures has been increased due to chlorides from sea sand and deicing salt. Therefore, a number of researchs are proceeding to prevent the corrosion of the reinforced steel in concrete, especially in marine environments. This study focused on the effect of corrosion inhibitors to evaluate protection characteristics for mortar specimens containing clorides. Corrosion behaviors have been investigated by half-cell potential measurement, linear polarization method, AC impedance method, and cyclic polarization test after immersing in sea water for 7 years. A possitive effect of a corrosion inhibitor has been obtained.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10c
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• pp.217-222
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• 1998

In these days, mostof marine structures are constructed by reinforcement concrete due to economic reason. Theoretically, it is widely recognized that rebar in sound concrete is safe against corrosion because of the high alkalinity of concrete. However, corrosion for reinforcement concrete made by marine aggregate and exposed to ocean enviroments has become serious social problem. Especially in Korea, with the rapid economic growth construction activities have been accelerated and needed more natural aggregate. Therefore, inevitably marine aggregate had to be used due to limitation of good quality aggregate. In this study, as a part of efforts to establish the fundamental counterplan on corrosion problems related to marine aggregate, concrete specimens with chloride containing material and inhibitor have been studied. And, in order to analyze corrosion characteristics several electrochemical techniques including half-cell potential survery, linear and cyclic polarization tests were carried out.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.1193-1198
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• 2001

The glass of Ground Granulated Blast Furnace Slag(GGBFS) was released by the hydroxyl ions during the hydration of the Portland cement. That results in relatively less $Ca(OH)_{2}$ in the concrete replaced with GGBFS than in ordinary portland cement concrete(OPCC). As the quantity of $Ca(OH)_{2}$ is decreased, the rate of carbonation in the concrete replaced GGBFS is faster than OPCC. Therefore, it has been misunderstood that the concrete replaced GGBFS has negative effect on the corrosion of steel by carbonation. Therefore, this study aimed at the relation between carbonation and rebar corrsion in the concrete with GGBFS, measuring air.water permeability, half cell, and corrosion rate by the depth of carbonation.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.1185-1192
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• 2001

This paper reviews available techniques for monitoring corrosion of steel in concrete. The need for early detection and diagnosis of corrosion related deterioration in reinforced structures is widely acknowledged. This is particularly important in reinforced concrete structures on account of the economic and social significance of the problem. The current generally used on-site procedure for corrosion monitoring of reinforced structures employs a method of half-cell surface potential measurements. While the technique has provided a useful means of delineating areas of high or low corrosion risk, there are difficulties in its use and interpretation when assessing rates of deterioration. Electrochemical techniques are by far the most suitable for corrosion monitoring purpose and meet most of the requirements. The aim of this paper is to describe the electric resistance sensor(ER sensor) and electrochemical techniques employed to monitor and estimate corrosion rates of reinforcement. Early detection and diagnosis of corrosion hazards allows preventive measures to be taken, hence the typically expensive repair of severely deteriorated structures can be avoided.

• Journal of electromagnetic engineering and science
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• v.13 no.1
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• pp.1-7
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• 2013

This paper proposes a metamaterial (MTM) absorber for 2.45 GHz band applications. The unit cell of the proposed absorber consists of an electric LC (ELC) resonator and a strip line, which are printed on opposite sides of the substrate. The ELC resonator comprises two split ring resonators (SRRs) and a connecting line with a resistor. The designed absorber exhibits an absorption of 94 % and a half-max bandwidth of 0.16 GHz at 2.45 GHz.

• Journal of Advanced Marine Engineering and Technology
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• v.25 no.6
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• pp.1272-1280
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• 2001

SrS:Ce thin films for blue EL devices were prepared by Hot Wall Method and their crystallographic and optical characteristics were investigated by various methods. Deposition rates were increased with SrS cell temperature, but the rates were independent on substrate temperature and sulfur pressure. The optical and crystallographic characteristics were strongly affected by deposition rates. The band gap energies obtained by optical transmission spectra and Full Width at Half Maximum of (200) plane in X-ray diffraction patterns were found at 4.5-4.6eV and $0.22~0.26^{\circ}$, respectively. The photoluminescence from SrS:Ce thin tiles showed a greenish blue omission peaked at 470 and 540nm.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1997.04a
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• pp.3-5
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• 1997

Properties of a good drug include safety, efficacy, half-life and bioavailability. With the current approach to drug discovery based on receptor-based and cell-based screening methods, compounds are frequently moved into development with poor bioavailability. With low bioavailability, drug administration is typically limited to parenteral routes, thus limiting the potential wide-spread utility of these therapeutic agents. The first and most important factor limiting a drug's bioavailability is the intestinal membrane permeability which in turn determines the maximum fi:action of the dose administered that can be absorbed. We have recently utilized new intubation methods for performing permeability measurements in humans and establishing a fundamental human data base for correlating intestinal jejunal membrane permeabilities with permeabilities determined in other systems, e.g., animals, tissue culture, as well as physical chemical properties.

• Journal of the Korean Society of Combustion
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• v.8 no.1
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• pp.46-56
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• 2003

The present paper is concerned with the development of the computational biology in the past half century and its relationship with combustion. The modem computational biology is considered to be initiated by the work of Alan Turing on the morphogenesis in 1952. This paper first touches the life and scientific achievement of Alan Turing and his theory on the morphogenesis based on the reactive-diffusive instability, called the Turing instability. The theory of Turing instability was later extended to the nonlinear realm of the reactive-diffusive systems, which is discussed in the framework of the excitable media by using the Oregonator model. Then, combustion analogies of the Turing instability and excitable media are discussed for the cellular instability, pattern forming combustion phenomena and flame edge. Finally, the recent efforts on numerical simulations of biological systems, employing the detailed bio-chemical knietic mechanism is discussed along with the possibility of applying the numerical combustion techniques to the computational cell biology.

• Structural Engineering and Mechanics
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• v.61 no.2
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• pp.171-181
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• 2017

This paper summarizes the study on effect of ceramic waste powder as partial substitute to cement in binary blend and along with silica fume in ternary blend high strength concrete in normal and aggressive environments. Strength parameters such as compression & tension and durability indices such as corrosion measurement, deterioration, water absorption and porosity were studied. Ceramic waste powder was used in three different percentages namely 5, 10 and 15 with constant percentage of silica fume (1%) as substitutes to cement in ternary blend high strength concrete was investigated. After a detailed investigation, it was understood that concrete with 15% ceramic waste powder registered maximum performance. Increase of ceramic waste powder offered better resistance to deterioration of concrete.