• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.537-542
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• 2001

Recently long-span bridges, such as Kwang-Ahn Grand bridge, Seo-Hae Grand Bridge, Young-Jong Grand Bridge, etc, have been designed and constructed near the shore. It needs to maintain the durability of marine concrete structures which are exposed to severe chloride environments. It is well known that corrosion of reinforcement steels in concrete structure is the most important cause for the durability of concrete structure which can be controlled by systematic preparatory corrosion protection works for economic and safe infrastructures. Various corrosion protection systems have been used for the corrosion protection of reinforcement steels from detrimental chemical components such as chloride, sulphate and etc. Since chloride can be penetrated into concrete in a variety way, an effective method has to be adopted by taking into full economical aspects and technical data of each protection system. The objective of this experimental study is to investigate the corrosion behavior of reinforcing steel in laboratory concrete specimens which are exposed to cyclic wet and dry saltwater, and then to develop pertinent corrosion protection system, such as corrosion inhibitors and cathodic protection for reinforced concrete bridges exposed to chloride environment. Resistance of various corrosion inhibitors and impressed current system have been experimentally evaluated under severe environmental conditions, and thus effective corrosion protection systems could have been Practically developed for future concrete construction.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.3
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• pp.414-417
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• 2014

At present, the demand for electric power increases, the electric power system is complicated. The size of the line-to-ground fault and the line-to-line fault occurred with complication of electric power system continue to increase, therefore several issues are raised. To address these issues effectively, the superconducting fault current limiter (SFCL) has been proposed, this study is ongoing. In this paper, we applied the SFCL in three-phase transformer and comparative analysis of the electric power burden to the SFCL. The superconductor is combined to the third winding of transformers in connection structure. In case of a third line-to-line fault, we did comparative analysis of the electric power burden to the SFCL based on the turn ratio of transformer third winding. In this case, we could confirm as the third turn ratio increased, electric power impressed to the superconducting element increased.

• Journal of the Korean Institute of Gas
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• v.12 no.1
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• pp.19-24
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• 2008

Due to industrialization and urbanization, underground metallic utilities with different owners have been rapidly increased and cathodic protection (CP) methods, especially impressed current CP systems, have been widely adopted to protect their utilities from corrosion with expanded recognition of this method. The stray current interference problem as well as the difficulty in spatial security for system installation, however, came to a ramification of which each owner couldn't resolve for himself. In this respect, this paper illustrates a field-diagnosed example for mutual interference due to separately operated CP systems and suggests an alternative method to overcome the interference situation by design and field-assessment of a common anode bed cathodic protection system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.6
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• pp.1515-1524
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• 2015

Recently, for the purpose of preventing the corrosion of a vessel, the electrical corrosion protection device that prevents the corrosions of the hull and the propeller is widely used. However, the electrical corrosion protection method artificially emits the current into the seawater around the hull using the power supply in order to make the hull and propeller be in the state of not being corrosion, so that electromagnetic field is generated outside the hull by the current emitted into the seawater. In this paper, the static and alternating constituents of the electromagnetic field generated in underwater outside the hull are analyzed and a countermeasure is investigated to reduce the strength of the electromagnetic field. In conventional shaft grounding system, the shaft potential is maintained above at least 100mV and the alternating current component constitutes more than 10% of the total current. However, in this paper, a control system was designed in order that the alternating current component and the shaft potential which generate electromagnetic field are maintained within 1% and 2mV respectively, and the performance was verified by simulation.

• Journal of Ocean Engineering and Technology
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• v.25 no.2
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• pp.85-91
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• 2011

Many protection methods such as surface coating, electric protection, or other methods have been applied to the numerous steel structures widely used in continental and marine areas to control their corrosion, which is done from an economic point of view. Most of these steel structures are primarily protected by coating methods. However, some steel piles under seawater are protected by the electric protection method, that is, either using an impressed current or a sacrificial anode method. Furthermore, environmental contamination may cause a severely corrosive environment, which, in turn, causes the accelerated corrosion of steel structures. Subsequently, coated steel structures could deteriorate more rapidly than the designed lifetime because of the acid rain caused by air pollution, etc. Therefore, a coating of marine paint exposed to seawater, that is, underwater hardening painting, is increasingly required to be fast drying as well as highly corrosion resistant. In this study, five types of underwater hardening paints were prepared with different resin series and additives. Their corrosion and water resistances were investigated using electrochemical methods such as corrosion potential, polarization curves, impedance and cyclic voltammogram measurements, etc. Even though it is generally accepted that the corrosion resistance of bare steel tends to increase with a shift of the corrosion potential in the noble direction, the corrosion resistance of a sample with a coating exhibited a relatively better tendency when it had a lower corrosion potential in this study. The corrosion current density was also decreased with a decrease in the diffusion limiting current density, which may mean that there is some relationship between corrosion and water resistance. The S sample of the ceramic resin series showed the relatively best corrosion and water resistance among those of samples, while the worst corrosion and water resistance were observed for the R sample of the epoxy resin series. The corrosion and water resistance of those samples tended to deteriorate with an increase in the immersion days, and their corrosion and water resistances were considered to be apparently improved by the types of resin and additives.