• 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.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2118-2122
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• 2005

This test was performed to assess the corelation of insulation deterioration condition with breakdown voltage of the stator winding of 3.3kV class induction motors which have been in service for 10 years after being installed in 1993. The insulation diagnostic tests include resistance, polarization index(P.I), dissipation factor$({\Delta}tan{\delta})$, maximum partial discharges (Qmax) and AC breakdown test. we evaluated the corelation of insulation diagnostic test with AC breakdown test for stator wilding of high voltage induction motor.

• Journal of the Korean Institute of Gas
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• v.5 no.4 s.16
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• pp.33-39
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• 2001

This paper was studied on corrosion behavior of absorption refrigeration systems using $LiBr-H_2O$ working fluids. In the various concentration of lithium bromide solution, polarization test of SS 400, Cu(C1220T-OL) and Al-Ni bronze is carried out. And the corrosion behavior of materials forming absorption refrigeration systems is investigated. The main results are as following: 1) As concentration of lithium bromide solution increases, polarization resistance of materials of each kinds is low. And open circuit potential becomes less noble, the corrosion current density is high drained 2) Open circuit potential of SS 400 is less noble than that of Cu and Al-Ni bronze, corrosion current density of SS5 400 is high drained than that of Cu and Al-Ni bronze. 3) Anodic polarization of Cu and Al-Ni bronze in $62\%$ LiBr solution continues the active state. that of Cu and Al-Ni bronze in the natural sea water maintains the active state and the critical current for passivation appears.

• Journal of Fisheries and Marine Sciences Education
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• v.15 no.2
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• pp.176-183
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• 2003

Recently, with the tendency of lightening, high-strength and high-speed in the marine industries such as marine structures, ships and propellers, it is rapidly enlarged the use of the aluminium alloy. Therefore, there occurs much interest in the study on corrosion characteristics of aluminium alloy. This paper was studied on the corrosion characteristics of Al-Mg alloy propeller used for a coasting vessel. Under the various pH of marine environment, the corrosion test of Al-Mg alloy was carried out. And thus polarization resistance, corrosion potential, and current density behavior of Al-Mg alloy and galvanic corrosion behavior of Al-brass and Al-Mg alloy coupled Al 5086 and SS 400 for hull were investigated. The main results are as following: 1. The corrosion potential of Al-brass propeller is more nobel than materials for hull, but that of Al-Mg alloy propeller is low or similar to materials for hull. Therefore, the galvanic corrosion of hull due to Al-Mg propeller don't occur. 2. The polarization resistance of Al-Mg alloy in sea water of pH 4 is highest, and corrosion current density of Al-Mg propeller is the most controlled. 3. As pH value decreases, potential showed Evans polarization diagram approaches cathodic potential. The corrosion current density of Al-Mg alloy is controlled to anodic reaction rate, therefore, the corrosion reaction of Al-Mg alloy is anodic control.

• Korean Journal of Materials Research
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• v.15 no.8
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• pp.536-542
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• 2005

Recently European Council(EU) published the RoHS(restriction of the use of certain hazardous substances in electrical and electronic equipment) which is prohibit the use of Pb, Hg, Cd, $Cr^{+6}$, PBB or PBDE in the electrical and electronic equipments. So EU member States shall ensure that, from 1 July 2006, new electrical and electronic equipment put on the market does not contain 6 hazardous substances. The one of the most important in electronics manufacturing process is soldering. Soldering process use the chemical substances which are applied in fluxing and cleaning processes and it can generate the malfunction of electronics caused by corrosion in the fields conditions. Therefore this study researched on the polarization and Tafel properties of Sn40Pb and Sn3.0Ag0.5Cu(SAC) solder based on the electrochemical theory. We prepared SnPb specimens which was aged in $150^{\circ}C,\;180^{\circ}C$ for 15 minutes ana Sn3.0Ag0.5Cu specimens that was aged in $180^{\circ}C,\;220^{\circ}C$ for 10 minutes. Experimental polarization curves were measured in distilled ionized water and $3.5 wt\%$, 1 mole NaCl electrolyte of $40^{\circ}C$, pH 7.5. Ag/AgCl and graphite were utilized by reference and counter electrode, respectively. To observe the electrochemical reaction, polarization test was conducted from -250 mV to +250 mV. From the polarization curves that were composed of anodic and cathodic curves, we obtained Tafel slop, reversible electrode potential(Ecorr) and exchange current density(Icorr). In these results, corrosion rate for two specimen were compared Sn3.0Ag0.5Cu with SnPb solders

• Journal of the Korea Concrete Institute
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• v.12 no.5
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• pp.69-80
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• 2000

This paper presents the prediction of remaining service life of the concrete due to steel corrosion caused by the following three cases; carbonation, using sea sand and using deicing salts. The assessment of initiation period was generalized considering the existing perdiction models in the literature, corrosion experiment and field assessment. To evaluate the prediction equation of rust growth, the corrosion accelerating experiments was performed. The polarization resistance was measured by potentiostat and the conversion coefficient of polarzation resistance to corrosion rate was determined by the measurement of real mass loss. Chloride content, carbonation, cover depth, relative humidity, water-cement ratio(W/C), and the use of deicing salts were taken into account and the resulting prediction equation of rust growth was proposed on the basis of these properties. The proposed equation is to predict the rust growth during any specified period of time and be effective in particular for predicting service life of concrete in the case of using sea sand.

• Journal of Power System Engineering
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• v.11 no.3
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• pp.41-46
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• 2007

The microstructure and electrochemical analysis of welds of electric resistance welding(ERW) pipe were investigated. The direction of metal flow line in HAZ of ERW pipe shifted to the inner(or outer) surface of pipe by plastic deformation during welding. The lowest heat input welds of ERW pipe was showed crack by liquid penetrant testing. Accelerated corrosion test by constant current density of 20mA/$cm^{2}$ developed groove at the welds of ERW pipe and the measured grooving factors were about $1.2{\sim}1.5$. Corrosion potential of base metal obtained by cyclic polarization in artificial sea water(3.5wt.% NaCl solution) was 100mV higher than that of weld metal of ERW pipe.

• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.262-265
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• 2007

Preliminary results are reported on ship detection using coherence images computed from cross-correlating images of multi-look-processed dual-polarization data (HH and HV) of ENVISAT ASAR. The traditional techniques of ship detection by radars such as CFAR (Constant False Alarm Rate) rely on the amplitude data, and therefore the detection tends to become difficult when the amplitudes of ships images are at similar level as the mean amplitude of surrounding sea clutter. The proposed method utilizes the property that the multi-look images of ships are correlated with each other. Because the inter-look images of sea surface are covered by uncorrelated speckle, cross-correlation of multi-look images yields the different degrees of coherence between the images and water. The polarimetric information of ships, land and intertidal zone are first compared based on the cross-correlation between HH and HV. In the next step, we examine the technique when the dual-polarization data are split into two multi-look Images.

• Journal of Electrochemical Science and Technology
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• v.10 no.2
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• pp.139-147
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• 2019

Incorporation of CuO nanoparticles during the polymerization of aniline in the presence of ammonium peroxydisulphate as an oxidizing agent and sodium salt of dodecylbenzene sulphonic acid as dopant as well as surfactant yielded water soluble CuO-PANI composite. Comparison of recorded spectra like FTIR, XRD and SEM with reported one confirm the formation of the composite. Analysis by gravimetric method exposes that the synthesized composite is having resistivity against corrosion, with slight variation in efficiency on extending the time duration up to eight hours in strong acidic condition. OCP measurement, potentiodynamic polarization and EIS studies also confirms the suppression ability of composite against corrosion. Riskless working environment could be provided by the synthesized composite during industrial cleaning process.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.333-335
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• 2005

The simulation of electric field distribution of discharge tube with globular $ZrO_2$ and the removal characteristic of Escherichia coli by the discharge tube with globular $ZrO_2$ were estimated. The removal characteristic of Escherichia coli was related to the input voltage because the electric field is increased according to input voltage. As the particle size of $ZrO_2$ beads increased, the removal time of Escherichia coli was shortened due to the dielectric polarization of $ZrO_2$ beads.