• Journal of the Korean Ceramic Society
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• v.38 no.6
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• pp.499-505
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• 2001

The behaviour of ionic compound crystals under combined chemical and externally applied electrical potential gradients is discussed. Firstly, a systematic overview is given. Then a formal analysis follows. The transport equations of the ions and the electric defects predict that even with reversible electrodes demixing, and in particular decomposition of the compound will occur if the applied d.c. current density is sufficiently high. These predictions are illustrated by appropriate experiments. With the help of the solid solution (Me, Fe)O, where Fe-ions are the dilute species, we investigate experimentally the behaviour of a ternary ionic crystal under a d.c. electric current load. All the compounds were placed in a galvanic cell, and the internal reactions which then could be observed were driven by the electric field in this cell. In addition, we discuss the influence of the electric field on the classical solid state reaction AX+BX=ABX$_2$, if again the reaction couple is placed in a galvanic cell.

• Journal of Advanced Marine Engineering and Technology
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• v.24 no.6
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• pp.78-88
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• 2000

The effect of post-weld heat treatment(PWHT) of SCM440 steel was investigated with parameters such as micro-Vickers hardness, corrosion potential, polarization behaviors, galvanic current, Al anode generating current and Al anode weight loss, etc. Each hardness of three parts(HAZ, BM, WM) by PWHT is lower than each of as-welded parts. However, hardness of WM area was the highest among those three parts in case of both PWHT and as-welded. Corrosion potential of WM part was the highest among those three parts and WM area was also acted as cathode without regard to PWHT. The magnitude of corrosion potential difference among three parts by PWHT was larger than that of three parts of as-welded, and corrosion current by galvanic cell of these three parts by PWHT was also larger compared to as-welded. Therefore, it is suggested that corrosion resistance property of SCM440 steel is decreased by PWHT than as-welded. However, both Al anode generating current and anode weight loss were also increased by PWHT compared to as-welded when SCM400 steel is cathodically protected by Al anode.

• Journal of Advanced Marine Engineering and Technology
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• v.24 no.5
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• pp.58-68
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• 2000

When SS400 steel was welded with low hydrogen type and ilmennite type welding, the effect of post-weld heat treatment(PWHT) was investigated with parameters such as micro vickers hardness, corrosion potential, polarization behaviors, galvanic current, Al anode generating current and Al anode weight loss etc. Hardness of each parts(HAZ, BM, WM) by PWHT in case of low hydrogen type and ilmennite type welding was lower than that of each parts by As-welded However hardness of WM area in case of low hydrogen type and ilmennite type welding was the highest among those three parts regardless of PWHT, Whereas in case of ilmennite type welding, WM area was the highest potential among these three parts on galvanic potential series with As-welded while BM area was the highest potential among these three parts by PWHT on the contrary. And in case of low hydrogen type welding, galvanic corrosion and micro cell corrosion of welding parts was decreased with PWHT. However, It was increased with PWHT in case of ilmennite type welding. Moreover Al anode generating current and anode weight loss in case of low hydrogen type was decreased by PWHT compared to As-wedled but, which was increased than that of As-welded in case of ilmennite type welding. Therefore, it is suggested that Corrosion resistance property in case of low hydrogen type welding is increased by PWHT. However its property was devreased with PWHT in case of ilmennite type welding.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.543-548
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• 2001

The corrosion monitoring methods of reinforcing steel in concrete are the various methods such as half cell potential method, galvanic current method, resistivity method, polarization resistance method, AC impedance method and etc. In this study, the corrosion monitoring methods of reinforcing steel in concrete were investigated for the test specimens using corrosion inhibitors, zinc-mortar, zinc-plate, respectively. For this purpose, the accelerated corrosion tests for reinforcing steel were conducted according to the periodic cycles(140 days) of wetting($65^{\circ}C$, 90% R.H.) and drying period(15$^{\circ}C$ , 65% R.H.) for the test specimens. As a result, it can be concluded from the test that half cell potential and galvanic current method as monitoring techniques for corrosion were found to be relatively reliable and easily usable method in the field.

• Journal of Power Electronics
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• v.16 no.4
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• pp.1277-1287
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• 2016

This study proposes a novel isolated high step-up galvanic converter, which is suitable for renewable energy applications and integrates a boost converter, a coupled inductor, a charge pump capacitor cell, and an LC snubber. The proposed converter comprises an input inductor and thus features a continuous input current, which extends the life of the renewable energy chip. Furthermore, the proposed converter can achieve a high voltage gain without an extremely large duty cycle and turn ratio of the coupled inductor by using the charge pump capacitor cell. The leakage inductance energy can be recycled to the output capacitor of the boost converter via the LC snubber and then transferred to the output load. As a result, the voltage spike can be suppressed to a low voltage level. Finally, the basic operating principles and experimental results are provided to verify the effectiveness of the proposed converter.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.5
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• pp.559-568
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• 2019

Recently, the infrastructure of the marine environment has been increasing. Therefore, there has been increasing interest in increasing the durability of structures. The FRP Hybrid Bar with improved durability against corrosion was developed in recent years. On the other hand, studies that evaluate the corrosion resistance are insufficient. In this study, the corrosion resistance according to the type of rebar in concrete was assessed and analyzed. The experiment used steel bars and FRP Hybrid Bar. The corrosion test method was a galvanic current and half-cell potential method. The accelerated corrosion test was carried out by four levels (0%, 1.5%, 3%, and 6%) of chloride added to the concrete. The galvanic current measurements revealed no corrosion current in the FRP Hybrid Bar. The half-cell measurement also showed the corrosion resistance of the FRP Hybrid Bar. Therefore. FHB can be used as an alternative steel for structures where a marine environment and steel corrosion are predicted.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.19 no.1
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• pp.57-62
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• 1983

The galvanic anodes have three kinds of Zn alloy anode, Al alloy anode and Mg alloy anode, which are widely used in cathodic protection for all metal structures in water or under ground. This paper to be used for designing of the grounding cell has reached the following conclusion as the results of an experimental study on the characteristics of such galvanic anodes for corrosion protection of pipings: 1) Zn alloy anode was the best when the specific resistance of the environment was bellow 1000 $\Omega$.cm, and when above 1000 $\Omega$.cm, Mg alloy anode to be used for designing of the grounding cell was the best. 2) Al alloy anode was better than Mg alloy anode for grounding cell when the specific resistance was bellow 500 $\Omega$.cm, but the Al alloy anode in all the environments reduced the characteristics of galvanic anode to the lower grade than those of Zn alloy anode. 3) Each impressed voltage (E) of the anodes at which drainage current density ($\rho$) begins rapidly increasing is quantitatively presented as follows: \circled1 E sub(Zn)=log (4.9465/$\rho$super(0.0639))+11$\times$10 super(-6)$\rho$super(0.8923i) \circled2 E sub(Al)=log (4.9306/$\rho$super(0.0525))+13$\times$10 super(-6)$\rho$super(0.9314i) \circled3 E sub(Mg)= log (3.7086/$\rho$super(0.0988))+181$\times$10 super(-6)$\rho$super(0.5406i) 4) The empirical equations between the drainage current density (i) and impressed environment are modeled as the following type. logi=g+root(n.E+r)(g,n,r; constants)

• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.2
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• pp.160-166
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• 2015

On board hydrogen generation from the hydrolysis of an active metal is very attractive due to its economical, convenient, and safe reasons. A Mg-graphite pellet has been designed as a hydrogen source for portable fuel cell. Mg (1 g) + 0.10 g graphite pellet showed an excellent hydrogen generation rate that is equivalent to 15.8 ml/g.min from its hydrolysis. The hydrogen generation rate of the pellet is significantly increased due to the galvanic corrosion by galvanic cells between Mg anode and graphite cathode in a 10.wt. % NaCl solution at a room temperature.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.179-180
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• 2010

The literature of present study was performed with content of chloride by total 6 level. After casting, and then, to measure the results of corrosion in a quick time used accelerated method of corrosion during 20 weeks. Both Galvanic and Half-cell for 20 weeks was used to model the initial time to corrosion, and then current of corrosion was measured by using Linear polarization at the end of cycling. The processing of steel used in concrete is same way as the case of mortar and also the initial time of corrosion was measured.

• Journal of Korea Foundry Society
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• v.37 no.3
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• pp.63-70
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• 2017

In the present study, effects of an addition of Sn on the microstructure and corrosion behavior were investigated in Mg-4%Zn-(0-3)%Sn casting alloys. With an increase in the Sn content, the ${\alpha}-(Mg)$ dendritic cell size was reduced, whereas the total amount of precipitates increased due to the formation of the $Mg_2Sn$ phase. It was found in immersion and electrochemical corrosion tests that the addition of Sn has a detrimental effect on the corrosion resistance of the Mg-4%Zn alloy. Microstructural examinations of the corrosion product and the corroded surface indicated that an accelerated micro-galvanic effect by the $Mg_2Sn-phase$ particles and a less protective corrosion product on the surface were responsible for the increased corrosion rate at a higher Sn content.