• Corrosion Science and Technology
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• 제6권3호
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• pp.90-95
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• 2007

Cathodic protection technology has been widely used on ship's outer hull and inner side of ballast water tanks as a supplementary corrosion protection measure in combination with protective organic coatings. Impressed current cathodic protection system is typically opted for the ship's hull and, sacrificial anode system, for ballast water tanks. The anticipation and interest in cathodic protection system for ships has been surprisingly low-eyed to date in comparison with protective coatings. Computational analysis for the verification of cathodic protection design has been tried sometimes for offshore marine structures, however, in commercial shipbuilding section, decades old design practice is still applied, and no systematic or analytical verification work has been done for that. In this respect, over-rotection from un-erified initial design protocol has been also concerned by several experts. Especially, it was frequently reported in sacrificial anode system that even after full design life time, anode was remaining nearly intact. Another issue for impressed current system, for example, is that the anode shield area design for ship's outer hull should be compromised with actual application situation, because the state-of-the-art design equation is quite impractical from the applicator's stand. Besides that, in this study, some other critical design issues for sacrificial anode and impressed current cathodic protection system were discussed.

• Corrosion Science and Technology
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• 제7권4호
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• pp.197-200
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• 2008

In this paper, physical scale modeling was employed to identify the configurations of ICCP system and the electric field signatures. Computational boundary element modeling technique has been used to simulate the performance of the CP system and to predict the associated electric fields signatures. The optimization methods combined with the computer models and physical scale modeling will be presented here, which enable the optimum system design to be achieved both in terms of the location and current output of the anode but also in the location of reference electrodes for impressed current cathodic protection(ICCP) systems. The combined methodology was utilized to determine optimal placement of ICCP components (anodes and reference electrodes) and to evaluate performance of ICCP system for the 2%, 10% and 14% wetted hull coatings loss. The objective is to design the system to minimise the electric field while at the same time provide adequate protection for the ship. The results show that experimental scale modeling and computational modeling techniques can be used in concert to design an optimum ICCP system and to provide information for quickly analysis of the system and its surrounding environment.

• 콘크리트학회지
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• 제11권2호
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• pp.221-230
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• 1999

콘크리트 구조물에 균열이 생겨 물과 산소의 침투확산이 용이해 지거나 또는 외부로부터 염소이온과 같은 염화물이 침투확산되어 콘크리트 중의 철근까지 도달할 경우 및 콘크리트의 중성화가 철근위치까지 진행될 경우 철근의 부동태 피막은 파괴되어 부식이 급진전 되며 콘크리트의 박리 및 탈락현상이 수반될 뿐만 아니라 구조물의 내구성이 크게 저하된다. 본 연구에서는 콘크리트 중의 철근부식을 억제하기 위한 한 방안으로 적용되는 전기방식의 이론적인 고찰과 콘크리트 내부에 다량의 염화물을 함유시키거나 또는 균열을 발생시킨 시험체에 대하여 외부전원법을 활용한 실내실험을 실시하여 철근의 방식효과에 대해 고찰하였다. 외부전원법에 의한 전기방식을 실시하여 복극량을 측정한 결과 대상 시험체 모두 NACE의 방식기준을 만족하였으며, 부식면적율의 측정결과 34 ~84%, 단면감소의 경우 84 ~ 86%의 방식효과를 확인하였다.

• 한국구조물진단유지관리공학회 논문집
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• 제3권2호
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• pp.213-220
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• 1999

The purpose of this study is to apply cathodic protection to reinforced concrete structure and provide fundamental data to prevent the corrosion. The theory of cathodic protection of steel in concrete is to apply sufficient direct current so that corroding anodes on the steel are prevented from discharging ions. Two methods are used to supply the external current. In one, the protected metal is the cathode by connecting it to a more active metal. In the second, an external direct current power source supplies the current. The first is the sacrificial-anode system and the second the impressed-current system. The study results showed that the corrosion of the reinforcing steel in concrete could be enormously decreased by using protective current. The sacrificial anode and concrete nave to be adhered closely each in order to prevent the corrosion of reinforcing steel.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 봄 학술발표회 논문집
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• pp.197-202
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• 1997

Recently the interest in the reinforcing steel corrosion due to the use of sea-sand and deicing salt, marine environment, and carbonation in RC structures is increasing, therefore the studies on the corrosion control of reinforcing steel in concrete are vigorously proceeding. In this study, from the viewpoint of electrochemical process of steel corrosion in concrete we applied the impressed current system among the cathodic protections to reinforcing steel in concrete and ascertained the protection effect by half-cell potential, corrosion rate, and depolarization.

• 조명전기설비학회논문지
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• 제30권1호
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• pp.55-65
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• 2016

This paper proposed a new control method which is capable of controlling circulating current considering current capacity of switching device. In the unbalanced voltage conditions, active power and reactive power have double line frequency. Thus, in order to provide active power without ripple, it is necessary to inject the negative sequence current components. However, when the negative current components is injected, it increases the total current flowing in the Arm, and in the Sub-module(SM) the current more than rated is impressed, which leads to destroy the system. Also, in impressing the circulating current reference of each arm, conventional control method impressed applicable $i_{dck}/3$ in the case of balanced voltage conditions. In the case of unbalanced conditions, as arm circulating current of three phase show difference due to the power impressed to each arm, reference of each arm is not identical. In this study, in the case of unbalanced voltage, within permitted current, the control method to decrease the ripple of active power is proposed, through circulating current control and current limitations. This control method has the advantage that calculates the maximum active power possible to generate capacity and impressed the current reference for that much. Also, in impressing circulating current reference, a new control method proposes to impress the reference from calculating active power of each phase. The proposed control method is verified through the simulation results, using the PSCAD/EMTDC.

• Journal of Advanced Marine Engineering and Technology
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• 제37권3호
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• pp.260-265
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• 2013

Impressed current cathodic protection (ICCP) system is one of the most promising corrosion protection methods. The Effect of ICCP system can be changed at diverse conditions. Particularly, temperature and relative humidity plays a crucial role in CP (Cathodic Protection) effect. Thus, in this study, the influence of temperature and relative humidity on concrete specimens was investigated. Specimens were concrete slab type with a base of $400mm{\times}400mm$ and height of 70mm. To enhance the effect of CP system, seawater was used as an electrolyte. Used anode for ICCP system was mixed metal oxide (MMO) titanium. Test factors were natural potential, CP potential, CP current, and 4-hour depolarization potential. From this study, it could be confirm that CP potential and current were highly influenced by temperature and relative humidity.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.134-136
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• 2008

In recent years, the switched reluctance motor have been used many industrial application because of its cost advantage. SRM drivers are accomplished by switching the phase currents on and off synchronously with the rotor position which is fed back to the controller by position may deteriorate in harsh environments and increase the size and cost of the SRM drive system. This paper proposes a position sensorless method that is based on impressed pulse voltage using impressed at unenergised phases to estimate the rotor position. The current value by impressed pulse voltage compare with the threshold value. The rotor position can be estimated by observing the current value. Finally, simulation results compare with the sensor type SRM and confirm the proposed method to be useful.

• 동력기계공학회지
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• 제10권2호
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• pp.104-110
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• 2006

Corrosion has been around for all of recorded history. Cathodic protection is the electrical solution to the corrosion problem. Corrosion is not exactly a new topic. It has been around since the beginning of time. Corrosion is simply the loss of material resulting from current leaving a metal, following through a medium, and returning to the metal at a different point. Corrosion takes many forms and has various names, such as oxidation, rust, chemical, and bacteria action. Regardless of the agent, all corrosion is the result of electrical current flow. Various methods are used to treat corrosion or to try to prevent ti. Some of these include chemical treatment. coatings, and electrical current. Especially, proper impressed current can stop corrosive action on the protected surface. In this article, we introduce the Impressed Current Cathodic Protection (ICCP) Control and monitoring system developed by ourselves. The ICCP system is composed of a power supply, anode, reference electrode and controller. The main issue is to control the current flow on the desired value such that it is possible to force a metal to be more negative(cathodic) than the natural state. From the this process, we can achieve the cathodic protection. Of course, in the developed system, the necessary functions are possessed, such as remote control, monitoring of system fault detection etc. Some experimental results show the system performance and usefulness.

• 한국생산제조학회지
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• 제20권2호
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• pp.139-144
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• 2011

This paper presents a boundary element application to determine the optimal impressed current densities at defect position on the pipe line. In this protection paint, enough current must be impressed to lower the potential distribution on the metal surface to the critical values. The optimal impressed current densities are determined in order to minimize the power supply for protection. This inverse problem was formulated by employing the boundary element method. Since the system of linear equations obtained was ill-conditioned, including singular value decomposition, conjugate gradient method were applied and the accuracies of these estimation. Several numerical examples are presented to demonstrate the practical applicability of the proposed method.