• The Korean Journal of Pesticide Science
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• v.2 no.2
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• pp.59-67
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• 1998

토양중 침투성 살충제 carbofuran과 제초제 petilachlor의 용탈행적을 구명하기 위하여 물리화학적 성질이 상이한 2종의 논토양으로 충전된 토양 column (내경 5cm ${\times}$ 길이 30cm)에 $^{14}C$-표지 화합물을 각각 처리한 후 벼 (Oryza sativa L.)를 생육시키면서 벼를 심지 않은 경우를 대조구로 하여 8주 동안 주당 95.2 ml씩 용탈시켰다. Carbofuran의 경우 토양 column에서 용탈된 $^{14}C$ 방사능의 양은 벼를 재배하지 않은 토양 A와 B에서 각각 총처리 방사능의 74.8와 92.3%였으며, 벼를 재배한 토양에서는 각각 45.1%와 69.7%였다. 반면에 petilachlor의 경우 벼를 재배한 토양 column에서는 각각 총처리 방사능의 2.4%와 5.0%가 용탈되었으며, 벼를 재배한 경우는 각각 3.1%와 8.2%가 용탈되었다. 토양에 처리한 [$^{14}C$]화합물 모두 벼의 생육유무에 관계없이 양이온치환용량, 유기물 및 점토의 함량이 적은 토양 B에서 $^{14}C$ 방사능의 용탈이 증가되었다. 토양 column중 carbofuran의 이동성은 매우 높은 반면에 petilachlor는 매우 낮았으며, 이는 그들의 토양흡착과 수용성에 기인된 것으로 판단된다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.6
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• pp.90-96
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• 2014

The electrical resistivity of concrete can be related to two processes involved in corrosion of reinforcement: initiation (chloride penetration) and propagation (corrosion rate). The resisistivity of concrete structure exposed to chloride indicates the risk of early corrosion damage, because a low resistivity is related to rapid chloride penetration and to high corrosion rate. Concrete resistivity is a geometry-independent material property that describes the electrical resistance, which is the ratio between applied voltage and resulting current in a unit cell. In previous study, it was realized that the resistivity of concrete depended on the moisture content in the concrete, microstructural properties, and environmental attack such as carbonation. The current is carried by ions dissolved in the pore liquid. While some data exist on the relationship between moisture content on electrical resistivity of concrete, very little research has been conducted to evaluate the effect of chloride on the conduction of electricity through concrete. The purpose of this study is to examine and quantify the effect of chloride content on surface electrical resistivity measurement of concrete. It was obvious that chloride content had influenced the resistivity of concrete and the relationship showed a linear function. That is, concrete with chloride ions had a comparatively lower resistivity. Decreasing rate of resistivity of concrete was clear at early time, however, after 50 days resistivity was constant irrespective of chloride concentration. Conclusively, this paper suggested the quantitive solution to depict the electrical resistivity of concrete with chloride content.

• Journal of the Korea Concrete Institute
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• v.29 no.1
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• pp.65-75
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• 2017

C-S-H phase is the most abundant reaction product, occupying about 50~60% of cement paste volume. The phase is also responsible for most of engineering properties of cement paste. This is not because it is intrinsically strong or stable, but because it forms a continuous layer that binds together the original cement particles into a cohesive whole. The binding ability of C-S-H phase arises from its nanometer-level structure. In terms of chloride penetration in concrete, C-S-H phase is known to adsorb chloride ions, however, its mechanism is very complicated and still not clear. The purpose of this study is to examine the interaction between chloride ions and C-S-H phase with various Ca/Si ratios and identify the adsorption mechanism. C-S-H phase can absorb chloride ions with 3 steps. In the C-S-H phase with low Ca/Si ratios, momentary physical adsorption could not be expected. Physical adsorption is strongly dependent on electro-kinetic interaction between surface area of C-S-H phase and chloride ions. For C-S-H phase with high Ca/Si ratio, electrical kinetic interaction was strongly activated and the amount of surface complexation increased. However, chemical adsorption could not be activated for C-S-H phase with high Ca/Si ratio. The reason can be explained in such a speculation that chloride ions cannot be penetrated and adsorbed chemically. Thus, the maximum chloride adsorption capacity was obtained from the C-S-H phase with a 1.50 Ca/Si ratio.

• Journal of the Korea Concrete Institute
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• v.16 no.2 s.80
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• pp.261-268
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• 2004

Corrosion of reinforcement is the main cause of damage and early failure of reinforced concrete structures. The corrosion is mainly progressed by the chloride ingress. In this paper, an experimental study is executed to investigate the effect of concrete properties and testing methods on the coefficients of chloride diffusion. Also, it is surveyed the relationship between total chloride and free chloride in concrete. According to this experiment results, W/C ratio and testing method affect chloride diffusion coefficient of concrete. As W/C ratio is increased, diffusion coefficient in concrete is also increased. Diffusion coefficient obtained by each testing method show the different values, respectively. The model equation of diffusion coefficient with W/C ratio is proposed.

• The Korean Journal of Pesticide Science
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• v.15 no.1
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• pp.1-7
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• 2011

In order to enhance the fungicidal activity of the thifluzamide formulation against rice sheath blight, the surfactants which was able to facilitate the foliar uptake or increase the leaf deposit of thifluzamide on rice plants were selected, and the formulations containing the surfactants were tested to compare the fungicidal efficacy against the rice sheath blight with a control WP formulation. The WP suspension containing dodecaethylene glycol monohexadecyl ether as an activator increased the foliar uptake of thifluzamide on rice plants, but its fungicidal efficacy against rice sheath blight was decreased. The addition of the combined surfactants with either heptaethylene glycol monoisododecy ether or heptaethylene glycol monotridecyl ether and sodium dioctylsulfosuccinate to WP suspension increased the leaf deposition of thif1uzamide at around 5 times of that without a spreader-sticker that median control concentrations of thifluzamide against rice sheath blight were decreased to 4.4 mg $L^{-1}$ and 3.4 mg $L^{-1}$, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.2
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• pp.1188-1194
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• 2014

The purpose of this study is to estimate Chloride Attack Resistibility and mechanical properties of quaternary concrete adding fly ash, blast-furnace slag, and silica fume. Compressive strength, modulus of elasticity, chloride migration coefficient, charge passed from Rapid chloride penetration test(RCPT), and immersion testing in 3% NaCl are tested. Chloride migration coefficient and charge passed of quaternary concrete measured $0.032{\times}10^{-12}m^2/sec$ and 650 coulomb at 17 weeks, which are in a permitted limit. Also in immersion test, depth of chloride penetration and maximum chloride ion of quaternary concrete measured 3.7 mm and $10.211kg/m^3$ respectively. From the results, quaternary concrete adding fly ash, blast-furnace slag, and silica fume denotes improvement of mechanical properties and chloride attack resistibility.

• Journal of the Korean Recycled Construction Resources Institute
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• v.1 no.2
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• pp.136-143
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• 2013

In the sewage structures and wastewater facilities, concrete is exposed to hydrogen sulfide ($H_2S$) which acts as an acid material in a solution, and a strongly acidic sulfate ion ($SO{_4}^{-2}$) is generated by a sulfuric bacteria. Hence, a degradation of concrete with biochemical corrosion would be accelerated. Finally, durability of concrete and concrete structures may be greatly reduced. In this study, in order to remove the hydrogen sulfide which is used by the sulfuric bacteria organic-biologically, the antibiotic metal and metallic salt powders were mixed to concrete, and a suppressing performance of the sulfate ion was assessed. For the sulfuric acid bacteria, a comparative evaluation of antimicrobial performance on neutralized concrete specimens were carried out, also by a rapid chloride penetration test, chloride penetration depths and diffusion coefficients were measured for antibiotic concrete in accordance with the amount of metal and metallic salt-based antibacterial agents. Eventually, by an observation of the biochemical state of the surface of concrete specimens exposed outdoors, the performance and applicability of antibiotic concrete were confirmed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.4
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• pp.18-24
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• 2012

In this study, hybrid method using polyvinyl acetate (PVAc) which has a strong adhesion and flexibility in which acrylic copolymer chemical-reaction reacts with cement, and is eco-friendly, is to improve the watertightness. The hybrid method is applied applied primarily waterproof stuff comprising silicate system and secondary mortar mixed with PVAc on the concrete surface. And then, in order to evaluate the performance, the properties of bond strength and amount of water absorption were measured. Based on the above experiments, mock-up specimens for field application were fabricated, and then the properties were evaluated as laboratory experiments. As the results, specimens cast from hybrid method using PVAc showed the best results on watertightness and bond strength. And also, with respect to experiment of mock-up specimens, the properties were in agreement with laboratory results. Especially, it could know that PVAc has strengthening effect from the results of the compressive strength. Due to outstanding results of carbonation depth and resistance to chloride ion penetration, it may be applied in weak areas such as underground and marine structures.

• Journal of Soil and Groundwater Environment
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• v.6 no.3
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• pp.3-12
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• 2001

This study conducted to Investigate the movement of fertilized nutrients in a volcanic ash soil in Jeju using by the pressure-vacuum soil water sampler. The percolated water to measure the ion concentration of leachates was taken from a lysimeter at depths of 20, 40, 60, 80, 100 and 120 cm in the soil in where a corn and potato were cultivated as a preceding and succeeding crop, respectively. Fertilizers of N-$P_2$O$_{5}$-$K_2$O were applied at the rate of 36-30-30 kg $10a^{-1}$ for the corn and 28-22-24 kg $10a^{-1}$ for the potato prior to planting of both crops. The highest concentrations of Cl , $NO_3$-N, $Ca^{+2}$ and $K^+$ in percolates were showed at 20cm and 40cm in soil depth at one month after fertilizing, and then gradually moved and reduced into below soil depths. At 5.5 months after fertilization, the concentrations in all soil depths were similar with the value of before fertilization. At depth of 120cm, the concentration of NO$_3$-N and the other cations in leachate was highest 1 to 1.5 months after fertilization. pH in percolated water was negatively correlated with NO$_3$-N concentration while the concentration of $NO_3$-N showed positive correlation between Cl, $Ca^{+2}$ and $Mg^{+2}$ concentrations. This result indicated that those cations can be leached out by accompanied with $NO_3$-N.

• Journal of the Korea Institute of Building Construction
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• v.23 no.3
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• pp.221-229
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• 2023

This research aimed to conduct an empirical assessment of the penetration of chloride and sulfate ions into mortar sections using an anion exchange membrane(AEM) and laser-induced breakdown spectroscopy(LIBS). The study involved a simultaneous ion chromatography(IC) analysis and LIBS analysis performed on mortars immersed in varying concentrations of chloride and sulfate. The findings revealed that at the wavelengths specific to Chloride(837.59nm) and Sulfur(921.30nm), the LIBS intensity achieved using AEM surpassed that obtained with a paper substrate at equivalent penetration concentrations. A robust correlation was confirmed between LIBS intensity and chloride ion concentration. Furthermore, when juxtaposed with IC analysis concentration outcomes at identical depths, the AEM displayed a higher intensity. The research noted an enhancement in LIBS intensity and a diminution in errors within the low-concentration section when deploying AEM. However, for the Sulfur wavelength of 921.3nm, there remains a need to augment the sensitivity of the LIBS signal within the low-concentration section in future studies. The findings underscore the potential of employing AEM and LIBS for precise analysis of chloride and sulfate ion penetration into mortar sections. This strategy can aid in bolstering assessment precision and mitigating errors, particularly in regions with low concentrations. It is recommended to further research and develop methods to amplify the sensitivity of the LIBS signal for sulfur detection in low-concentration sections. In sum, the study accentuates the significance of employing advanced techniques like AEM and LIBS for efficacious and precise analysis in the domain of mortar section assessment.