• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.13 no.5
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• pp.403-411
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• 2020

Since the analog circuit of the beta ray sensor circuit for the true random number generator and the power and ground line used in the comparator circuit are shared with each other, the power generated by the digital switching of the comparator circuit and the voltage drop at the ground line was the cause of the decreasein the output signal voltage drop at the analog circuit including CSA (Charge Sensitive Amplifier). Therefore, in this paper, the output signal voltage of the analog circuit including the CSAcircuit is reduced by separating the power and ground line used in the comparator circuit, which is the source of digital switching noise, from the power and ground line of the analog circuit. In addition, in the voltage-to-voltage converter circuit that converts VREF (=1.195V) voltage to VREF_VCOM and VREF_VTHR voltage, there was a problem that the VREF_VCOM and VREF_VTHR voltages decrease because the driving current flowing through each current mirror varies due to channel length modulation effect at a high voltage VDD of 5.5V when the drain voltage of the PMOS current mirror is different when driving the IREF through the PMOS current mirror. Therefore, in this paper, since the PMOS diode is added to the PMOS current mirror of the voltage-to-voltage converter circuit, the voltages of VREF_VCOM and VREF_VTHR do not go down at a high voltage of 5.5V.

• Journal of Pharmaceutical Investigation
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• v.36 no.3
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• pp.185-192
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• 2006

The purpose of this study was to determine the effects of iontophoresis on transdermal delivery of procaine hydrochloride in healthy volunteers, as well as to the synergic effect of high voltage current or ultrasound on the efficacy of transdermal delivery of iontophoresis. Forty healthy volunteers were randomly assigned to four groups topical application group (TA), iontophoresis group (IT), pre-treatment of high voltage current stimulation with iontophoresis (HVS + IT), and pre-treatment of ultrasound application with iontophoresis (US + IT). All subjects received procaine iontophoresis on the forearm using direct current with 4 mA f3r 15 minutes. All subject was measured the duration of local anesthesia, pressure pain threshold, pain perception threshold using rectangular wave at 0.2 ms, 1 ms, 50 ms of rectangular current stimulation after procaine iontophoresis. For comparisons of the sensory characteristics and efficacy of iontophoresis between the groups, an one-way ANOVA and Kruskal-Wallis were used. The significant difference the duration of local anesthesia were found between the groups (p<0.001). The local anesthetic duration of IT, HVS+IT were significantly longer than TA. Meanwhile, the local anesthetic duration of US+IT was significantly longer than HVS+IT, IT and TA group (p<0.05). Also, the pressure pain threshold, pain perception threshold at 0.2 ms, 1 ms, 50 ms were significant difference between the groups (p<0.001). All sensory characteristics including pressure pain threshold, pain perception threshold of IT, HVS+IT was significantly increased than TA, whereas, US+1T was significantly increased HVS+1T, IT and TA (p<0.05). This study showed that the procaine iontophoresis have increase the duration of local anesthesia concomitantly pressure pain threshold and pain perception threshold of sensory nerve fibers such as $A-{\beta}$, $A-{\delta}$ and C fiber. This findings suggest that the iontophoresis enhanced the transdermal delivery of drug ions in vivo. The combination of ultrasound application and iontophoresis synergized the transdermal delivery of drug ions. It is suggests that an electric field, mechanical and heating property of ultrasound may contribute to synergic effect due to temporary changes of structure in the stratum corneum.

• Journal of Welding and Joining
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• v.35 no.1
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• pp.34-42
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• 2017

This paper presents a comparative study of the AC and MFDC resistance spot welding process with consideration of sheet thickness. The previous studies have confirmed that there is difference in the optimum welding current and expulsion current with AC and MFDC. The aim of this study was revealing the effect of sheet thickness on weldable current range and expulsion behavior for AC and MFDC welding processes. The optimum welding current of AC was lower (1.6 kA) than MFDC welding process in 0.8 mm sheet thickness. Early nugget growth being caused by the peak current of AC developed weld interface deformation, which resulted in suppressing the growth of corona bond and occurrence of low current expulsion. The resistance spot welding for thicker sheet (1.4 mm) required lower current of 0.6 kA for the expulsion on the MFDC welding process. The growth of contact diameter (size of corona bond) and button diameter was linear up to the expulsion current with MFDC welding process. Therefore, more attention is required when the AC and MFDC resistance spot welding process is applied for different thickness of steel sheet combination for automotive application.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.5
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• pp.462-473
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• 1999

This paper addresses the current measurement issue of all digital field oriented control of ac motors. The p paper focuses on the effect of low-pass filter and also on the sampling of the fundamental component of the m motor current. The low-pass filter, which suppresses the switching noise of the motor current, introduces v variable phase delay according to the current ripple frequency. It is shown that the current sampling error c consists of the fundamental component and high frL'quency ripple components. In this paper, the dependency of t this current sampling e$\pi$or on the reference voltage vector is investigated analytically and a sampling technique i is proposed to minimize the error. The work is based on the three phase symmetry pulse width modulation l inverter driving an induction machine. With this technique, the bandwidth of current regulator can be extended t to the limit given by the switching frequency of the inverter and more precise torque regulation is possible.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.10
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• pp.29-34
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• 2007

The fault current limiting characteristics of a flux-lock type superconducting fault current limiter(SFCL) according to fault angles were investigated. From the electrical equivalent circuit with the magnetization branch, the inner magnetic flux of this SFCL due to fault angles was induced and its effect on the limited fault current was analyzed. From the fault current limiting experiments, the exciting current, which described the saturation of the iron core, was calculated and its dependence on the fault angle was analyzed. Before the fault happened, the exciting current did not happen, that it kept zero value. However, after the fault happened, the exciting current flowed and, the exciting current in case of the additive polarity winding showed higher value than for the case of the subtractive polarity winding. The analysis results were compared with the experimental ones, and experimental results agreed with the analysis ones.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.5
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• pp.992-997
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• 2016

This paper analyzes the deviation of tunneling current for the ratio of top and bottom gate oxide thickness of short channel asymmetric double gate(DG) MOSFET. The ratio of tunneling current for off current significantly increases if channel length reduces to 5 nm. This short channel effect occurs for asymmetric DGMOSFET having different top and bottom gate oxide structure. The ratio of tunneling current in off current with parameters of channel length and thickness, doping concentration, and top/bottom gate voltages is calculated in this study, and the influence of tunneling current to occur in short channel is investigated. The analytical potential distribution is obtained using Poisson equation and tunneling current using WKB(Wentzel-Kramers-Brillouin). As a result, tunneling current is greatly changed for the ratio of top and bottom gate oxide thickness in short channel asymmetric DGMOSFET, specially according to channel length, channel thickness, doping concentration, and top/bottom gate voltages.

• Journal of Korea Society of Industrial Information Systems
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• v.23 no.1
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• pp.43-52
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• 2018

This paper presents the performance of a Phase Shift Full Bridge (PSFB) converter with inductive load and a new current control scheme to improve dynamic response of output current with various inductive loads. Enhanced dynamic model is used which includes leakage inductance and inductive load. Effect of changing of inductive load was analyzed in detail. Proposed current control scheme is designed based on phase margin specifications. As a result, the proposed current control scheme helps to improve the dynamic response in comparison with the existing current control scheme. The performance of the designed controller is verified by a 500 A PSFB converter. The results will be utilized for high current applications with high inductive load such as superconducting devices.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.4
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• pp.1191-1201
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• 2014

The rip current warning index function, which estimates the likelihood of dangerous rip current in the real-time rip current warning system operating to help mitigate against rip current accidents at Haeundae beach, was studied. The rip current warning index evaluated as a function of various real-time observations was developed based on Choi et al. (2013b). This study shows a version of rip current warning index improved by including the effect of wave direction and spreadings of frequency-directional spectrum on rip current likelihood. The wave and tidal observations in 2012 at Haeundae coast were applied to the rip current index function, and its performances at several real events found based on CCTV images were presented and analyzed.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.12
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• pp.90-95
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• 2009

The application of a large power transformer into a power distribution system was inevitable due to the increase of power demand and distributed generation. However, the decrease of the power transformer‘s impedance causes the short-circuit current of the power distribution system to increase and thus, the higher short-circuit current exceeds the cut-off ratings of the protective devices such as a circuit breaker. To solve these problems, several countermeasures have been proposed to protect the power system effectively from the higher fault current and the superconducting fault current limiter (SFCL) has been expected to be the promising countermeasure. However, the current limiting effect of SFCL including its bus voltage drop compensation depends on SFCL's application location in a distributed power system. In this paper, the current limiting and the bus-voltage drop compensating characteristics of the SFCL applied into a power distribution system were studied. In addition, the quench and the recovery characteristics of the SFCLs in each location of the power distribution system were compared each other.

• Applied Chemistry for Engineering
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• v.34 no.3
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• pp.272-278
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• 2023

In this study, we analyzed the effects of current density and electroosmotic phenomena on the desalination performance of electrodialysis (ED). We conducted ED experiments under constant voltage conditions, changing the concentration of the concentrate solution from 10 to 200 g/L. During the ED operation, we measured the current density and charge supplied to the stack, the concentration of the diluted and concentrated solutions, and the amount of water transported by electroosmosis to analyze desalination performance. As the concentration of the concentrated solution increased, the selectivity of the ion exchange membrane decreased, resulting in a decrease in current efficiency. Moreover, the current efficiency was found to be influenced by the current density supplied. When the current density exceeded 15 mA/cm², back diffusion of ions was suppressed, leading to an increase in current efficiency. We also investigated the specific water transport by electroosmosis during the ED operation. We found that the amount of water transported increased proportionally to the concentration ratio of the concentrated and diluted solutions. When the concentration ratio exceeded 100, the specific water transport rapidly increased due to osmotic pressure, making it challenging to obtain a concentrated solution greater than 200 g/L.