• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.49-52
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• 2005

This study was performed to evaluate antibacterial performance antibiotics(RCF-95, Antibio-C) which could control biochemical corrosion of concrete used sewage facilities by sulfate oxidizing bacteria. As antibacterial methods, Broth MIC testing was used for investigating controlled growth effect of sulfate oxidizing bacteria. Also, color-changed testing by indicator was used for confirming between $H_{2}SO_{4}$ diffusion rate by bacteria and antibiotics. It confirmed that Antibio-C was superior to RCF-95 in the antibacterial performance and hence anticipated that this developed Antibio-C was enough to replace imported antibiotics from Japan.

• Journal of Ocean Engineering and Technology
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• v.13 no.1 s.31
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• pp.121-129
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• 1999

Double-diffusive convection with verical temperature and concentration gradients in thermally stratified fluids has been investigated experimentally using an electrochemical technique. Cupric sulfuric-sulffuric acid solution confined between two horizontal copper electrodes was used. The change of thermal and solutal buoyance has no influence on the range of voltage for the limiting current. Due to Soret effect, the onset time of natural convection is delayed as the stabilizing thermal buoyancy decreases. Also it is found that the shrinkage of the unstabilizing solutal buoyancy makes the onset of natural convection retard. Multi-layered convective phenomena do not appear because cupric sulfate-sulfuric acid solution is thermally stratified, and heat diffuses faster than cupric sulfate solfate solution.

• Applied Chemistry for Engineering
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• v.8 no.4
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• pp.645-652
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• 1997

Electrochemical characteristics and kinetic parameters of copper ion reduction were investigated with a platinum rotating disk electrode (RDE) in a diffusion controlled region. Reduction of Cu(II) in sulfate had one-step two-xelectron process, while the reduction of Cu(II) in chloride solution was involved two one-electron processes. The transfer coefficient of Cu(II) in sulfate solution was lowest, and the transfer coefficient of Cu(I) in halide solutions had the value of nearly one. In chloride solutions, electrodeposition rate of Cu(II) was about one hundred times faster than Cu(I). Diffusion coefficient increased in the order of Cu(II) in chloride solution, Cu(I) in the iodide, bromide, chloride solution, Cu(II) in sulfate solution. The calculated ionic radii and activation energy for diffusion decreased in the same order as above. Morphological study on the copper electrodeposition indicated that the electrode surface became rougher as both concentration and reduction potential increases, and the roughness of the surface was analyzed with UV/VIS spectrophotometer.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.771-776
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• 2001

Test results on the deterioration process of concrete under single and combined attacks of chloride penetration have been obtained. After test period of 52 weeks, it is found that the internally penetrated chloride ion contents are less in the single attacks of chloride than the combined attacks of chloride and sulfate. Both the diffusion coefficients and surface chloride concentration derived form the chloride profiles showed a time dependence. Also the performance of fly ash-blended cements was observed to be better than plain cements in retarding chloride attack. However it should be needed that improved chloride diffusion model for the combined deterioration process.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.721-726
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• 2003

The Durability of Concrete Structure is serverely degraded due to mainly carbonation, sulfate attack and chloride ion diffusion in concrete. The ultimate purpose of this study is to obtain how much the durability of Concrete Structure is improved according to the variation of physical properties in concrete or the frequency of surface coating on concrete. Where, variation of physical properties is a water-cement ratio or amount of air. The experiments are the chliride ion diffusion test, the lapid corrosion test, the lapid carbonation test, the test on resistance to freezing and thawing. Finally, this study shows that the effect by the surface coating method is better than the variation of physical properties in concrete.

• YAKHAK HOEJI
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• v.4 no.1
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• pp.47-49
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• 1959

Another application of the new quantitative analytical method of prussic acid by "Microdiffusion analysis" for the determination of prussic acid in human blood was studied. The blood containing potassium cyanide was dropped in outer room of unit, and then N-sulfuric acid was added. The liberated HCN gas was absorbed into nickel sulfate solution of inner room, afterward, absorbed prussic acid was determined with EDTA by residual titration. The result was coincided with the result of Liebig Denigs' method at ordinary temperature.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.1
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• pp.36-42
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• 2005

This study examined the feasibility of producing sulfuric acid and ammonia water from ammonium sulfate solution using two-compartment electrodialysis with a bipolar membrane (EDBM). Electrodialysis experiments were carried out with 20 wt% ammonium sulfate at different current densities and sulfuric acid concentrations in a concentrate compartment. The current efficiency increased with the current density from 25 to $100\;mA/cm^2$. Nevertheless, the efficiency was relatively low compared with that of general desalting electrodialysis, owing to the diffusion of sulfuric acid from the concentrate compartment to the diluate. The diffusion rate through the anion exchange membrane increased with the sulfuric acid concentration in the concentrate compartment, which decreased the current efficiency. Conversely, the electrical resistance decreased with increasing current density owing to the Joulian heat generated during water dissociation in the transition region of the bipolar membrane under a high electric field. From the experimental results, we concluded that operating at a higher current density is effective from the perspective of current efficiency and electrical resistance when producing sulfuric acid and ammonia water from ammonium sulfate using a two-compartment EDBM process. Further studies on the effects of increasing the sulfuric acid concentration on current efficiency are required to apply the EDBM process practically.

• Journal of the Korean Wood Science and Technology
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• v.19 no.4
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• pp.7-17
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• 1991

The feasibility of treating three softwood(Japanese larch pitch pine, and Korean pine) thinned logs by double-diffusion treatment processes was investigated. Some posts were incised before immersion, and others were imersed in hot copper sulfate solution. Comparison among species indicated that. in general, pitch pine was most treatable and Japanese larch least treatable. For all three species, almost all treatment schedules gave consistently good penetration and high net retention, but very steep gradient of preservative distribution. As expected, the treatability was increased by the extension of immersion time, increased concentration of treating solution, incising. and heating of the first solution. Of the variables tested, it appears that heating of the first solution is the most important. From the data in this paper, it may be concluded that, if the first solution is not heated, the best schedule is #3. If the first solution is healed. it appears the best schedules are #10 or #11. Since heating of the first solution improves the treatability. schedules # 10 or :#11 are recommended if the cost of heating might be justified. The data presented in this paper indicate that double-diffusion treatment processes seem to offer a promise as a comparatively effective and easy-operating method of treating thinned logs for the small-scale production of treated stock.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.2
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• pp.149-156
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• 2016

It has been well known that concrete structures exposed to chloride and sulfate attack environments lead to significant deterioration in their durability due to chloride ion and sulfate ion attack. The purpose of this experimental research is to evaluate the long-term durability against chloride ion and sulfate attack of the alkali activated cementless concrete replacing the cement with ground granulated blast furnace slag. For this purpose, the cementless concrete specimens were made for water-binder ratios of 40%, 45%, and 50%, respectively and then this specimens were cured in the water of $20{\pm}3^{\circ}C$ and immersed in fresh water, 10% sodium sulfate solution for 28, 91, 182, and 365 days, respectively. To evaluate the long-term durability to chloride ion and sulfate attack for the cementless concrete specimens, the diffusion coefficient for chloride ion and compressive strength ratio, mass change ratio, and length change ratio were measured according to the NT BUILD 492 and JSTM C 7401, respectively. It was observed from the test results that the resistance against chloride ion and sulfate attack of the cemetntless concrete were comparatively largely increased than those of OPC concrete irrespective of water-binder ratio.

• Journal of the Korea Concrete Institute
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• v.14 no.5
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• pp.708-717
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• 2002

Durability is a major concern in the design and construction of concrete structures which are located in the sea environments. In particular, the combined action of chlorides, sulfates, and carbonation nay influence greatly the deterioration behavior of concrete structures. The purpose of the present study is to explore the diffusion characteristics of chloride ions in concrete structures under combined deterioration conditions. The present test results indicate that the chloride penetration into concrete structures is more pronounced under combined attacks of chlorides, sulfates and carbonation. The diffusion coefficients and surface chloride contents were found to increase under combined multiple deterioration conditions. The present study provides quantitatively the penetration and diffusion characteristics of chloride ions in concrete structures under various deterioration conditions. The results of present study may be efficiently used for the realistic design of concrete structures under combined deterioration conditions.