• Journal of the Korean Ceramic Society
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• v.44 no.9
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• pp.524-528
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• 2007

The results of evaluating steel corrosion in concrete containing chloride content of various levels indicated that the more chloride content in concrete leads to the lower potential and higher corrosion current density. However, the open circuit potential of steel varied with time and exposure condition, and the corelation between the open circuit potential and corrosion current density was not obvious. In order to determine the critical threshold content of chloride of steel corrosion in concrete, the concept of average corrosion current density was employed. The range of critical chloride content in portland cement concretes was about $1.56{\sim}1.77%$($Cl^-$, %, wt of cement content) along with water-cement ratio, and higher water-cement ratio resulted in reduction in critical threshold chloride content.

• Applied Chemistry for Engineering
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• v.9 no.4
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• pp.523-528
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• 1998

The electrochemical characteristics of $V_2O_5$ as working electrode were studied in the cell (1-butene+$O_2$, $V_2O_5{\mid}YSZ{\mid}Ag$, $O_2$) with a YSZ solid electrolyte. The sintering of Ag as a counter electrode was occurred after calcination, and the structure which has the pores of over $3{\mu}m$ was achieved. In particular, the peak of (010) plane of the working electrode on the XRD spectrum which is responsible for selective oxidation appeared after calcination. The major product of 1-butene oxidation over $V_2O_5$ was butadiene. The technique of SEP (solid electrolyte potentiometry) was used to monitor the chemical potential of chemical species adsorbed on the working electrode. Over a wide range of gas compositions of 1-butene and oxygen, open circuit voltage (OCV) exhibited the mixed potential of surface oxygen activity.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.1
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• pp.124-132
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• 2022

The corrosion potential in concrete varies greatly with exposure and concrete mix conditions. In this study, RC (Reinforcement Concrete) samples were prepared considering cover depth, chloride concentration, and W/C(water to cement) ratio as variables, and HCP(Half Cell Potential) was measured, which evaluated comparative potential between embedded steel and concrete surface. In addition, OCP(Open Circuit Potential) was measured using buried steel and CE(Counter Electrode). Agar and NaOH solution were used as ion exchange materials and Hg/HgO was used for RE(Reference Electrode), which was more sensitive to temperature than HCP. Among the influencing factors, the exposure period and chloride concentration had a relatively greater effect than cover depth and w/c ratio. Additionally, the entire measured HCP and OCP showed a clearly linear relationship with increasing cover depth and w/c ratio. Through multiple regression analysis, the relationship between HCP and OCP was quantified, and an improved correlation was obtained with temperature effect.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.50 no.11
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• pp.550-556
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• 2001

The computerized cardiac analysis system, which acquires and analyzes the electrical activation signal propagating along the surface of the heart, is indispensible equipment for the open heart surgery and electrical cardiac study. In this paper, the design requirement and the electrical circuit analysis are performed to construct the multi-channel cardiac activation pre-amplifier necessary for a signal conditioning circuit. The general 64 channel configuration is expanded into 128 channels to enhance the spatial resolution on the mapped surface of the heart. The 128 channels pre-amplifier consists of input circuit, differential amplifier, right leg driven circuit and isolation part. It has distinct features; high voltage protection, leakage current limitation, isolation and the maximization of common mode rejection ratio with respect to the half-cell potential difference due to different electrode materials. The final pre-amplifier circuit is assembled with 8 boards, each of which composing of 16 channels.

• Journal of the Korea Safety Management & Science
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• v.2 no.4
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• pp.187-195
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• 2000

Electrochemical promotion of the reaction rate was investigated for CO oxidation in a solid electrolyte catalytic reactor where a thin film of Pt was deposited on the yttria stabilized zirconia as an electrode as well as a catalyst. It was shown under open circuit condition that potential was a mixed potential of $O_2$exchange reaction and electrochemical reaction induced by CO. The effect of electrochemical modification on the CO oxidation rate was studied at various overpotentials and $P_{CO}$$P_{O2}$.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2002.05a
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• pp.135-139
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• 2002

Most of all the mechanical devices are becoming more high-speed and high-power as well as their used condition being more polluted. So, it is necessary for these devices to equip cooling system to overcome that kind of severe using condition. In this study, corrosion test was carried out in distilled and tap water for the investigation on the corrosion characteristics of Al-alloy that is using as material for radiator.

• Journal of Fisheries and Marine Sciences Education
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• v.12 no.2
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• pp.164-175
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• 2000

Port facilities and marine structures used in marine environment were encountered to corrosion damages because of the influence of Cl-. Generally, to protect these accidents, anti-corrosion paint and epoxy coating have been used. But they were still remained erosion-corrosion damage like impingement erosion, cavitation erosion and deposit attack. It is necessary to develope the new composite lining material in order to protective those corrosion damages. In this paper, polyester glass flake, vinylester glass flake lining and epoxy coating for SS400 were investigated by the electrochemical polarization test and the impingement-cavitation erosion test for corrosion behaviour under the sea water. The main results obtained are as follows ; 1) Epoxy coating appear potentiodynamic polarization behaviour, but polyester glass flake and vinylester glass flake lining do not appear potentiodynamic polarization behaviour. 2) Open circuit potential of polyester glass flake lining is more noble than that of epoxy coating and corrosion current density of polyester glass flake lining is less drained than that of epoxy coating in sea water. 3) Open circuit potential of vinylester glass flake lining is more noble than that of polyester glass flake lining and corrosion current density of vinylester glass flake lining is less drained than that of polyester glass flake lining in the sea water.

• Journal of Advanced Marine Engineering and Technology
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• v.25 no.6
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• pp.1336-1340
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• 2001

Due to increase of air pollution substance, such as $SO_2$,$SO_3$, H2S ,CO, HCI, $Cl_2$ and so on, the operating environment of mechanical equipment and facilities like generating plants, ships, metal structure etc., are acidified and corroded. In these environments, the crevice corrosion of marine facilities frequently occurs at crevice like jointed bolt, gasket or sealant, riveted plates, contact of metal with non-metallic solids etc. Therefore, this paper was studied on the crevice corrosion behavior of mild steel(SS 400) in marine environment. In a variety of NaCl solutions, the aspect of he .crevice corrosion and polarization behavior under the crevice corrosion was investigated. The main results obtained are as follows: 1) Under crevice corrosion, the open circuit potential become less treble as the concentration of NaCl solution increased. 2) The corrosion current density of mild steel was high drained as the concentration of NaCl solution increased by 3.5%, but in the concentration increased over 3.5%, the corrosion current density was low drained. 3) The crevice corrosion is more sensitive to the synergy effect of dissolved oxygen and NaCl.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2006.06a
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• pp.271-272
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• 2006

Zinc confers high corrosion resistance by acting as a sacrificial anode, and a zinc coating improves the appearance of steel. Chromate conversion coating (CCC) films are still one of the most efficient surface treatments for steel. Although such films can self-repair via the dissolution of Cr(VI), dissolved Cr(VI) have adverse effects on humans, and the environment. Therefore, we examined the corrosion protection property and morphology of colloidal silica conversion films as an alternative to CCC films. The corrosion behavior was investigated in 3% NaCl solution using electrochemical techniques, including electrochemical impedance spectroscopy, open circuit potential, and the salt spray test(SST). Corrosion was implied by the appearance of red rust on the specimen surface. In corrosion resistance at 3% NaCl solution, red rust appeared at 15-20, 55-70, and 83-98 days on Zn-electroplated steel, colloidal silica conversion-coated specimens, and CCC-coated specimens, respectively. In the salt spray test, the colloidal silica film provided better corrosion protection than CCC films, i.e., red rust appeared at 96 hours on the Zn-electroplated steel sheet, at 432 hours with the CCC films, and at 888 hours with silica conversion coating.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2001.11a
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• pp.92-97
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• 2001

This paper was studied on the effect of temperature on corrosion of absorption refrigeration systems using LiBr-$H_2O$ working fluids. In the fresh water and 62 %lithium bromide solution at $70^{\circ}C$, polarization test of SS 400, Cu(Cl220T-OL) and Ni-Al bronze was carried out. And Polarization behavior, polarization resistance characteristics, corrosion rate(mmpy) and corrosion sensitivity of materials forming absorption refrigeration systems was considered. The main results are as following: As the experimental temperature increase, the change of corrosion rate of Ni-Al bronze become duller than SS 400 and Cu in 62 % lithium bromide solution. Open circuit potential of SS 400 is less noble than that of Cu and Ni-Al bronze in fresh water, but that becomes noble than Cu and Ni-Al bronze in 62 % lithium bromide solution. The corrosion sensitivity of Ni-Al bronze was controlled than that of Cu and SS 400 in 62% LiBr solution.