• Journal of Power Electronics
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• v.9 no.1
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• pp.68-73
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• 2009

Automotive inverters may require current sensors for motor torque control, especially, in applications of hybrid electric vehicles or fuel cell vehicles. In this paper, to achieve a compact, integrated and low cost current sensor, a hall current sensor without magnetic core is introduced for integrating an automotive inverter. The compactness of the current sensor is possible by using integrated magnetic concentrators based on the Hall effect. Magnetic fields caused by three-phase currents are analyzed and a magnetic shield design is proposed for decoupling the cross-coupled field. It offers galvanic isolation, wide bandwidth (>100kHz), and accuracy(< 1%). Using 2D FEM analysis, its performance is demonstrated with design parameters at a U-shaped magnetic shield. The proposed coreless current sensor is tested with rated current to validate the linearity and accuracy.

• Proceedings of the KSR Conference
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• 2000.11a
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• pp.535-542
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• 2000

Pure copper, Cu-1.1wt%Cd and ACSR(Aluminum Conductor Steel Reinforced) have been used as Catenary Materials in Electric Railway System. Since these materials may have chance to be exposed to the corrosive environments like polluted air, acid rain and sea water, it is important not only to investigate the corrosion characteristics but also to measure corrosion rates in various corrosive environments. In order to examine corrosion characteristics according to the dissolved oxygen content, pH, chloride ion concentration ion, and the addition of Cd to Cu, a series of tests such as potentiodynamic polarization. a.c impedance spectroscopy and galvanic corrosion tests were carried out in these materials. Results showed that the addition of Cd to Cu and chloride ion in the solution have an adverse effect on the resistance to corrosion. Additionally, Galvanic currents between Al and steel wires of ACSR were confirmed by using ZRA(zero resistance ammeter) method.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.7
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• pp.16-24
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• 2019

The corrosion amounts of steel structures can be different depending on their installation condition and height. Thus, their corrosion maintenance should be considered depending on installation conditions of local structural members. In this study, an atmospheric exposure test was conducted to evaluate the corrosion amount and the corrosion rate depending on the installation condition and height of a steel water gate using monitoring steel plates and corrosion environment measuring sensors. The mean corrosion depth was evaluated using the weight loss method and the galvanic corrosion current was measured by corrosion environment measuring sensors. Local corrosion rate of local structural member in steel water gate was estimated using measured mean corrosion depths and galvanic corrosion currents. From this measurement results, the corrosion damage in horizontal member of the cross beam was highly evaluated than those of other structural member as skin plate, etc. The relative difference in the corrosion rate of a local structural member could be highly affected by local corrosion environments of steel water gate members. Therefore, an appropriate maintenance method should be considered for local corrosion damages of local structural members determined by local corrosion environments of a steel water gate.

• Journal of the Korean institute of surface engineering
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• v.34 no.5
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• pp.435-444
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• 2001

WC-( $Ti_{1-x}$ A $l_{x}$) N coatings of constant changing Al concentration were deposited on S45C substrates by high-ionization sputtered PVD method. The Al concentration could be controlled by using evaporation source for Al and fixing the evaporation rate of the metals (i.e, WC- $Ti_{0.86}$A $l_{0.14}$N, WC- $Ti_{0.72}$A $l_{0.28}$N, and WC- $Ti_{0.58}$A $l_{0.42}$N). The corrosion behavior of WC-( $Ti_{1-x}$ A $l_{x}$)N coatings in a deaerated 3.5% NaCl solution was investigated by electrochemical corrosion tests and surface analyses. The measured galvanic corrosion currents between coating and substrate indicated that WC- $Ti_{0.72}$A $l_{0.28}$N coating showed the best resistance of the coating tested. The results of potentiodynamic polarization tests showed that the WC- $Ti_{0.72}$A $l_{0.28}$N coating deposited with 32W/c $m^2$ of Al target revealed higher corrosion resistance. This indicated that the WC- $Ti_{0.72}$A $l_{0.28}$N coating is effective in improving corrosion resistance. In EIS, the WC- $Ti_{0.72}$A $l_{0.28}$N coating showed one time constant loop and increased a polarization resistance of coating ( $R_{coat}$) relative to other samples. Compositional variations of WC-( $Ti_{1-x}$ A $l_{x}$)N coatings were analyzed by EDS and XRD analysis was performed to evaluate the crystal structure and compounds formation behavior. Surface morphologies of the films were observed using SEM and AFM. Scratch test was performed to measure film adhesion strength.strength. adhesion strength.strength.