• Corrosion Science and Technology
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• v.17 no.6
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• pp.310-316
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• 2018

The effect of passive film on corrosion of metals and alloys in a static corrosive environment has been studied by many researchers and is well known, however few studies have been conducted on the electrochemical measurement of metals and alloys during cavitation corrosion conditions, and there are no test standards for electrochemical measurements 'During cavitation' conditions. This study used commercially additive manufactured(AM) pure titanium in tests of anodic polarization, corrosion potential measurements, AC impedance measurements, and repassivation. Tests were performed in 3.5% NaCl solution under three conditions, 'No cavitation', 'After cavitation', and 'During cavitation' condition. When cavitation corrosion occurred, the passive current density was greatly increased, the corrosion potential largely lowered, and the passive film revealed a small polarization resistance. The current fluctuation by the passivation and repassivation phenomena was measured first, and this behavior was repeatedly generated at a very high speed. The electrochemical corrosion mechanism that occurred during cavitation corrosion was based on result of the electrochemical properties 'No cavitation', 'After cavitation', and 'During cavitation' conditions.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.4
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• pp.18-25
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• 2000

Ion current in an S.I engine cylinder is measured with the spark plug as a probe. The peak values are confirmed to show a fair correlation with local air-fuel ration and engine speed which implies that the ion current measured at the spark plug may provide a signal for the local mixture strength which is the key parameter in precise fuel control for future engines especially of gasoline direct-injected lean burn engines.

• Proceedings of the KIPE Conference
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• 1996.06a
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• pp.85-88
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• 1996

New power factor correction(PFC) technique based on the averaged model of boost converter is proposed. Without measurement of input current, power factor correction scheme derived from the averaged model is presented. With the measurements of input voltage and output voltage, the control signal is generated to make the shape of the line current same as the input voltage. The characteristics of input line current distortion is analyzed by considering the generation of duty cycle.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.4
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• pp.17-26
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• 1997

A enw channel current model of GaAs MeSFET suitagle for applications to microwave CAD has been developed. The current model includes the bias-dependent frequency dispersion effects and its parameters are extracted from the pulsed I-V measurements at several quiescent bias points. The model is verified by applying to the nonlinear circuit designs of power amplifier and MMIC mixer.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.12
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• pp.159-165
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• 1995

A gate-recessed structure is introduced to SOI MOSFET's in order to increase the source-to-drain breakdown voltage. A significant increase in the breakdown voltage is observed compared with that of a planar single source/drain SOI MOSFET without inducing the appreciable reduction of the current drivability. We have analyzed the origin of the breakdown voltage improvement by the substrate current measurements and 2-D device simulations, and shown that the breakdown voltage improvement is caused by the reductions in the impact ionization rate and the parasitic bipolar current gain.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.2
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• pp.60-64
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• 2001

The degradation process of silicone rubber was investigated by leakage current monitoring in Inclined-Plane method. DAS (Data Acquisition System) with 12-bit, 8-channel A/D converter was prepared. Average current, cumulative charge, current waveform and the number of peak pulses were measured on-line. And, FFT (Fast Fourier Transform) analysis was performed with stored current waveform. Besides, maximum erosion depth was measured in order to use as the indicator of the degradation process. So, the results of leakage current components and maximum erosion depth measurements were compared to find one or more components which have trends of changing similarly to that of erosion process. The result suggests that the ratio of peak current to r.m.s. current, harmonic contents and the number of peak pulses are well corresponding with the degradation process.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.34C no.10
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• pp.19-26
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• 1997

Novel class AB CMOS second-generation current conveyors (CCII) using 0.6.mu.m n-well CMOS process for high-frequency current-mode signal processing were developed. The CCII for low power operation consists of a class AB push-pull stage for the current input, a complementary source follower for the voltage input, and a cascode current mirror for the current output. In this architecture, the two input stages are coupled by current mirrors to reduce the current input impedance. Measurements of the fabricated CCII show that the current input impedance is 875.ohm. and the bandwidth of flat gain when used as a voltage amplifier extends beyond 4MHz. The power dissipation is 1.25mW and the active chip area is 0.2*0.15[mm$\^$2/].

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.6
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• pp.565-573
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• 2007

The effect of wave and current interactions on irregular wave transformation over a submerged elliptic shoal is investigated based on numerical simulations of the Vincent and Briggs experiment [Vincent, C.L., Briggs, M.J., 1989. Refraction-diffraction of irregular waves over a mound. Journal of Waterway, Port, Coastal and Ocean Engineering, 115(2), pp. 269-284]. The numerical simulations are conducted by a combination of REF/DIF S(a wave model) and SHORECIRC(a current model) and a time dependent phase-resolving wavecurrent model, FUNWAVE. In the simulations, the breaking-induced currents defocus waves behind the shoal and bring on a wave shadow zone that shows relatively low wave height distributions. The computed results of the combined model system agree better with the measurements than the computed results obtained by neglecting wave-current interaction do. In addition, the results of FUNWAVE show a good agreement with the measurements. The agreement indicates that it is necessary to take into account the effect of breaking-induced current on wave refraction when wave-breaking occurs over a submerged shoal.

• Journal of Engineering Education Research
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• v.16 no.6
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• pp.65-77
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• 2013

The purpose of this paper are to evaluate the program outcome(PO) for mechanical engineering program at Chosun University, In order to achieve the objectives of this study, we analyze the evaluation system on measuring and analyzed methods of PO. We expect that the evaluation system of PO will help program members to efficiently manage the engineering program accreditation evaluations. This paper were to improve PO evaluation system throughout assessment tools, measurements and analysis of PO between current students and faculty. This study would be confined measurements, analysis and improvement of PO for current students, and faculty in this program.

• Electrical & Electronic Materials
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• v.11 no.10
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• pp.94-99
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• 1998

Suitable replacement materials for ultrathin SiO2 in deeply scaled MOSFETs such as lattice polarizable films, which have much higherpermittivities than SiO2, have bandgaps of only 3.0 to 4.0 eV. Due to these small bandgaps, the reliability of these films as a gate insulator is a serious concern. Ramped voltage, time dependent dielectric breakdown, and hot carrier effect measurements were done on 190 layers of TiO2 which were deposited through the metal-organic chemical vapor deposition of titanium tetrakis-isopropoxide (TTIP). Measurements of the high and low frequency capacitance indicate that virtually no interface state are created during constant current injection stress. The increase in leakage upon electrical stress suggests that uncharged, near-interface states may be created in the TiO2 film near the SiO2 interfacial layer that allow a tunneling current component at low bias.