• IEMEK Journal of Embedded Systems and Applications
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• v.11 no.5
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• pp.305-312
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• 2016

Modern embedded systems are typically operated by the rechargeable batteries in our daily life. Since charge of batteries is considered as an time consuming task, there have been extensive efforts to manage the charge time from the perspective of materials, circuits, and systems. Estimation of battery charge time is one of the essential information to design the charge circuitry. A compact macro model for the constant-current and constant-voltage charge protocol was recently introduced, which gives us a quick estimation of charge time with similar shape to the famous Peukert's law for discharge time estimation. The CC-CV charging protocol is widely used for Lithium-based batteries and Lead-acid batteries. In this paper, we characterize the lead-acid battery by measurement to extract the model coefficients, which was not covered by the previous studies. By our proposed model, the key coefficient Kcc results in 1.18-1.31, which is little bit higher than that of Lithium batteries. The accuracy of our model is within the range of ${\pm}10%$ error, which is compatible with the other studies such as Peukert's law.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.4
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• pp.311-321
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• 2022

The report reviews recent research efforts in demonstrating a computing system whose operation principle mimics the dynamics of biological neurons. The temporal variation of the membrane potential of neurons is one of the key features that contribute to the information processing in the brain. We first summarize the neuron models that explain the experimentally observed change in the membrane potential. The function of ion channels is briefly introduced to understand such change from the molecular viewpoint. Dedicated circuits that can simulate the neuronal dynamics have been developed to reproduce the charging and discharging dynamics of neurons depending on the input ionic current from presynaptic neurons. Key elements include volatile memristors that can undergo volatile resistance switching depending on the voltage bias. This behavior called the threshold switching has been utilized to reproduce the spikes observed in the biological neurons. Various types of threshold switch have been applied in a different configuration in the hardware demonstration of neurons. Recent studies revealed that the memristor-based circuits could provide energy and space efficient options for the demonstration of neurons using the innate physical properties of materials compared to the options demonstrated with the conventional complementary metal-oxide-semiconductors (CMOS).

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.1106-1109
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• 2002

This paper introduces an improved pulse generator using power semiconductors. The proposed circuit consists of the series connected boost converter structure. In the presented circuits, high voltage pulse is generated by series-connection of capacitors and IGBTs. The charging of capacitors and voltage balance of IGBTs is done automatically. To verify the proposed circuit, 1kV, 25A pulse generator is manufactured and tested.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.189-192
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• 2001

This paper proposed that an AC-DC converter system using multiple buck-chopper operates with four choppers connecting to a number of parallel circuits. To improve these, a large number of soft switching topologies included a resonant circuit have been proposed. And, some simulative results on computer are included to confirm the validity of the analytical results. The partial resonant circuit makes use of an inductor using step-down and a condenser of loss-less snubber. The result is that the switching loss is very low and the efficiency of system is high. And the snubber condenser used in a partial resonant circuit makes charging energy regenerated at input power source for resonant operation. The proposed conversion system is deemed the most suitable for high power applications where the power switching devices are used.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.7
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• pp.937-942
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• 2013

Equivalent series impedance of high-voltage pulsed power capacitor is one of the important electrical characteristics both for users and for capacitor manufacturers because it may have serious effects on the performance of pulse forming circuits. In this paper, definition of equivalent series impedance and factors which generate equivalent series impedance are reviewed. Theoretical analysis for the calculation of equivalent series impedance based on differential measurement method is described and calculation program has been developed. In order to acquire data which are necessary to calculate equivalent series impedance from discharging current waveform, charging-dischargig controller has been manufactured. Measurement results of equivalent series impedance for high voltage pulsed power capacitor have been given.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.10a
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• pp.331-334
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• 2009

This paper presents the characteristics of external inductor for impulse current waveform with 10/350 ${\mu}s$ time parameters. Impulse generator was composed with capacitor having large capacitance and low working voltage for the safe of operator and small discharging sound. Parallel R-L-C circuits with crow-bar gaps and superposition method were proposed to make a high current lightning impulse according to IEC 62305-1. The high energy inductor with several taps for fitting half decay time T2 within the tolerance range and experimental data of inductance according to charging voltages were suggested.

• JSTS:Journal of Semiconductor Technology and Science
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• v.13 no.6
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• pp.562-568
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• 2013

This paper presents a design of a wireless power transfer system based on magnetic resonant coupling technology with in-band wireless communication. To increase the transmission distance and compensate for the change in the effective capacitance due to the varying distance, the proposed system used a loop antenna with a selectable capacitor array. Because the increased transmission distance enables multiple charging, we added a communication protocol operated at the same frequency band to manage a network and control power circuits. In order to achieve the efficient bandwidth in both power transfer mode and communication mode, the S-parameters of the loop antennas are adjusted by switching a series resistor. Our test results showed that the loop antenna achieved a high Q factor in power transfer mode and enough passband in communication mode.

• JSTS:Journal of Semiconductor Technology and Science
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• v.1 no.3
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• pp.167-181
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• 2001

A stepwise driving method was used for reducing the AC power consumption in a TFT-LCD. The AC power takes the largest portion of the total power consumption of a TFT-LCD. Experimental results confirmed that the AC power saving efficiency reached up to 75% when a 5-stepwise driving with each step time of $2\mu$ sec was applied to a 14.1 inch-diagonal XGA TFT-LCD. The second largest component of power consumption called the DC power comes from the quiescent currents in Op-amps. A simple and efficient architecture was proposed in this work to reduce this DC power consumption: Half of the Op-amps have the 5V-supplies, and the rest half have the 10V-supplies, and two Op-amps are shared by adjacent two channels. Measurements of test circuits showed that this simple method could reduce over 40% of the DC power consumption..

• Journal of the Korean Institute of Telematics and Electronics
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• v.14 no.4
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• pp.15-21
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• 1977

In this paper, an analogical method for measuring the electrical characteristics of the silent discharge in the Na2CO3 electrolyte is proposed by using an electrical equivalent model which consist of charging and discharging circuits. The electrical equivalent model is constructed with the use of zener diode and capacitor, and the electrical characteristics can be obtained by the voltage and charge traces which appear a simple parallelogram on the oscilloscope. The area enclosed by the parallelogram could be considered of the energy input per cycle, and is independent of the applied voltage waveform but dependent on the maximum applied voltage.

• Proceedings of the KIEE Conference
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• 1998.07b
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• pp.426-428
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• 1998

In this paper we describe a real time signal processing technique for the code correletion short range measurement sensor. Code correlation values are acquired via simple RC charging circuits within several tens of microsecond. Because the range measuring process is very fast and simple, the proposed technique is applicable to common near range targets as well as fast moving targets in real time. Some experimental results show the validity and usefulness of the proposed method.