• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.86.2-86
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• 2001

The method of pinpointing the place of the abnormalities of a power transmission system analyzes the voltage and the current information from the both ends of a power [1-2]. Now, there are only current and a voltage measuring instrument every about 20km, and the present condition is specifying the breaking down point by viewing of a worker in it. In this research, a power line circuit is assumed to be a line type system, and M-sequence is impressed to the end, it receives at other ends, the crosscorrelation function of input and output is taken, an impulse response is calculated, and the method in comparison with the time of normal is proposed. By this technique ...

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.4
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• pp.76-82
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• 2018

Grout in duct is very effective protection from tendon corrosion in PSC(Prestressed Concrete) structure. In the work, durability and mechanical tests are performed for two types of grout which are conventionally used one and the improved grout with reduced w/c (water to cement) ratio and silica fume. Tendon system with 1000mm height is prepared and various tests including strength, flow, absorption, and bleeding ratio are conducted. ICM(Impressed Current Method) is adopted for corrosion acceleration in tendon with 12.7mm diameter inside grout. For 2 and 4 days, corrosion acceleration is performed for 2 different type of grout and corrosion amount is investigated. The improved grout shows higher compressive strength by 10 MPa and lower absorption ratio by 50% than the conventional one. It also provides an excellent corrosion reduction to 39.8 %~48.2 % for 2~4 days of acceleration period.

• Proceedings of the KIEE Conference
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• 1990.11a
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• pp.161-165
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• 1990

KEPCO has experienced eight oil leakage failures due to POF cable corrosion in the 154KV underground POF cable transmission line since the line was operated in 1976. Experimentally, We have verified that the cause of the failure is electrolytic corrosion of the cable owing to subway leakage current. For the countermeasure, We adopted the total Cathodic Protection System by the use of Victim Anode, Forced Drainage Method and Impressed Current Method with polarization cell.

• Journal of Navigation and Port Research
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• v.30 no.4
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• pp.291-294
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• 2006

Corrosion is never avoided in the use rf materials with various environments. The underwater hull is normally protected against rusting by several coatings of anti-corrosive paint. The purpose of ICCP(Impressed Current Cathodic Protection) system is to eliminate the rusting or corrosion, which occurs on metal immersed in seawater. This thesis is about the ICCP control and monitoring system, which brings protection against the corrosion of the ship's hull in the sea environments. The test system for ICCP is composed of a power supply, anode, reference electrode and controller. The test system is composed power supply, anode, ref electrode, shunt and etc. The protection current is sent to the protection area though anode. Reference electrode senses whether or not the detected potential is within a range of protection of test equipment and then it is automatically controlled to increase or decrease the amount of protective current to be sent to the anode by controller. The monitoring system with LabView is also detected in order to check the normal state of the system at operation period, because an operator does not always watch over this system and thus the system cannot operate well because rf his or her negligent management. This paper was studied the variation of potential and current density with environment factors, velocity and time, and the experimental results will be explained Also, It is suggested that this system can accommodate a ship's automation for SCMS(Ship Control and Management System) and will be very useful.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.653-658
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• 2001

Recent 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. Thus, it needs to analyze the durability of marine concrete structures which are exposed to severe chloride environments. It is well known that corrosion of reinforcement steel in concrete is one of the major factors for the durability of concrete structures. The objective of this experimental study is to investigate the performance of impressed current system and corrosion inhibitors for the corrosion protection of reinforced concrete structures. Concrete test specimens were made with various test parameters, such as cover depth, steel diameter, compressive strength, direction and frequency of notch. For the efficient evaluation of these corrosion protection systems, these tests have been carried out in the shore.

• Journal of the Korean institute of surface engineering
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• v.40 no.6
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• pp.262-270
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• 2007

Recently, there has been a new appreciation of aluminum alloys as materials that are capable of reducing the environment load. This is because aluminum alloys are lightweight, easy to recycle, permit miniaturization, and have environmental friendly properties. In this study, we investigated the mechanical and electrochemical properties of 5083F aluminum alloys using slow strain rate test(SSRT) and potentiostatic tests under various potential conditions. In the potentiostatic tests, the current density in the potential range from -0.7 to -1.4V after 1,200 s was low. After considering the results of the potentiostatic tests, maximum tensile strength, yield strength, elongation, time-to-fracture, observation of fractured specimen and fractography analysis, the optimum protection potential range was between -1.3 and -0.7V(Ag/AgCl).

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.2
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• pp.217-226
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• 1996

Switched reluctance motor (SRM) drives appear today as viable alternatives to induction and brushless motor drives in a wide range of application such as machine tools, fans, and pumps. This paper deals with a new converter topology which can be used in order converter. The split source type converter consists of minimum switching devices to be used in switched reluctance motor (SRM) drive. In this proposed converter two switches and six diodes are added to split source type converter. The proposed converter has performance minimizes the negative torque, Which puts the phase current off by double impressed voltages. The major advangtage of this converter is the increase of the average output power while improving better converter efficiency in heavy load and high speed than other topologies. The proposed converter system has been implemented using 80C196KB microcontroller and experiments were carried out ot verify the simulation results.

• Journal of Ocean Engineering and Technology
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• v.27 no.3
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• pp.8-14
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• 2013

Although there are various factors that threaten the security of ships, one of the most harmful is corrosion. It is not easy to find corroding areas and the status of corrosion, even though corrosion causes serious problems such as submergence and marine pollution as a result of leaking oil and polluted water. To monitor the corrosion of ships, non-destructive inspection, weight loss coupons, electrical resistance, linear polarization resistance, zero resistance ammeter, and electrochemical impedance spectroscopy have been developed. However, these methods require much time to detect corrosion, and most are not appropriate for real time monitoring. Coating, sacrificial anode, and impressed current cathodic protection (ICCP) methods have been developed to control corrosion. The ICCP and sacrificial anode methods are the most popular ways to prevent ship corrosion. However, ICCP is only appropriate for the outside of a ship and cannot be used for complex structures such as ballast tanks because these are composed of many separate chambers. Sacrificial anodes have to be replaced periodically. This paper proposes an integrated corrosion monitoring and control system (ICMCS) that can detect corrosion in real time and is appropriate for complex structures such as ballast tanks. Because the system uses titanium for an anode, exhausted anodes do not need to be replaced.

• Corrosion Science and Technology
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• v.10 no.3
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• pp.101-107
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• 2011

Marine ships have played an important role as a carrier, transporting much more than 80% of all international trading, and marine transportation is an internationally competitive, strategic, and great national important industry. However, those marine ships have the characteristics such as voyage of long distance, large-volume and lower speed than the other carry system. Therefore, it is important to manufacture a larger and faster ship, however, the steel plates which are consisted with most of those ships has brought about many corrosion problems in sea water such as general corrosion, localized corrosion, cavitation and erosion corrosion etc.. Most hulls of the ships have been protected with paintings, sacrificial anode, marine growth prevention system, and impressed current cathodic protection methods against numerious corrosion problems mentioned above. However, these conventional methods are not very effective because the rudder of ships stern are exposed to very severe corrosive environment such as tides, speeds of ships, cavitations and erosion corrosion, etc.. In this study, electrochemical and cavitation characteristics was investigated for the rudder material of ship which is exposed to serious corrosive environment. As a result, it is considered that the optimum cathodic protection potentials of rudder material is the range of -0.6 V ~ -0.8 V(Ag/AgCl) in static seawater.

• Corrosion Science and Technology
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• v.18 no.3
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• pp.78-85
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• 2019

The International Maritime Organization (IMO) will administer a new 0.5% global sulfur cap on fuel content from 1 January 2020, lowering from the present 3.5% limit. Seawater $SO_x$ (sulfur oxide) scrubbing is especially spray scrubbing and a promising alternative to complying with the IMO regulation. However, the ionization of $SO_2$ (sulfur dioxide) and the $H_2SO_4$ (sulfuric acid) formed from $SO_3$ (sulfur trioxide) is proposed to accelerate corrosion of the internal seawater pipe. Apparently, the corrosion of the scrubber seawater piping system occurs in a severe and frequent manner. Hence, in this study, electrochemical measurement and weight loss of carbon steel (used as seawater pipe in most of the ships) in diluted sulfuric acid solution were investigated to determine corrosion rate, corrosion current density, corrosion potential, electrochemical behavior, and impressed-current density. Accordingly, the corrosion rate of carbon steel sheet in various diluted sulfuric acid solutions was observed to be greater than that in natural seawater, thus suggesting the fundamental data to deal with corrosion problems in scrubber seawater pipe.