• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.5
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• pp.1155-1161
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• 2014

This paper proposes a start-up voltage generator for reducing the minimum input supply voltage of DC-DC boost converters to 250mV. The proposed start-up voltage generator boosts 250mV input voltage to over 500mV to charge the capacitor for starting the boost converter. After the boost converter operates initially with the supply voltage charged in the capacitor, it uses its boosted output voltage for the supply voltage. Therefore, after the start-up operation, the proposed DC-DC boost converter works as the same as the conventional one. The proposed start-up voltage generator reduces the threshold voltage of the transistors by adjusting the body voltage at a low input voltage. This causes the higher clock frequency and the larger current to a Dickson charge-pump for boosting the input voltage. The proposed start-up voltage generator was implemented with a $0.18{\mu}m$ CMOS process. Its clock frequency and output voltage were 34.5kHz and 522mV at 250mV input voltage, respectively.

• Journal of Sensor Science and Technology
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• v.24 no.3
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• pp.165-168
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• 2015

We demonstrated low-voltage organic thin-film transistors (OTFTs) with bilayer insulators, high-k polymer and low temperature crosslinkable polymer, on a flexible plastic substrate. Poly (vinylidene fluoridetrifluoroethylene) (P(VDF-TrFE)) and poly (2-vinylnaphthalene) are used for high-k polymer gate insulator and low temperature crosslinkable polymer insulators, respectively. The mobility of flexible OTFTs is $0.17cm^2/Vs$ at gate voltages -5 V after bending operation.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.6
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• pp.75-81
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• 2013

In this paper, protection coordination between residual current devices and surge protective devices in low-voltage consumer's distribution systems are presented. In the case that a surge protrctive device(SPD) is located on the load side of an residual current device(RCD), when the surge is injected from the source side of the RCD, most of injected surge currents are split into the RCD and the protection coordination between the SPD and RCD is improper, three of 6 specimens experience unintended operation due to test impulse currents. Also when the surges is injected from the load side, a lot of the surge currents is split into the SPD, but a half of test specimens causes nuisance trip. Coordination between SPD and RCD is not valid. When installing SPD, it is important to select SPD after due consideration of the protection voltage level of metal oxide varistor embedded in RCD. It is expected that the results obtained from this work could be useful to improve the protection effects of SPD in low-voltage distribution systems.

• Journal of Satellite, Information and Communications
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• v.11 no.4
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• pp.21-26
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• 2016

The ESD(electrostatic discharge) protection performance of PPS(PMOS pass structure) embedded N-type silicon controlled rectifier(NSCR_PPS) device with different implant of channel blocking region was discussed for high voltage I/O applications. A conventional NSCR standard device shows low on-resistance, low snapback holding voltage and low thermal breakdown voltage, which may cause latch-up problem during normal operation. However, our proposed NSCR_PPS devices with modified channel blocking structure demonstrate the improved ESD protection performance as a function of channel implant variation. Therefore, the channel blocking implant was a important parameter. Since the modified device with CPS_PDr+HNF structure satisfied the design window, we confirmed the applicable possibility as a ESD protection device for high voltage operating microchips.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.3
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• pp.586-594
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• 2014

Maximizing the operating time by reducing the power consumption is important factor to operate sensor network under water networks. For efficient power consumption, dynamic voltage scaling method is available. This method operates low frequency when there is no workload. In case of abundant workload, high frequency operation completes hard work within short time, reducing power consumption. For this reason, complex cryptography should be computed in high frequency. In this paper, we apply dynamic voltage scaling method to cryptography and show performance evaluation. With this result, we can reduce power consumption for cryptography in under water communication.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.106-109
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• 2003

This paper describes an AC voltage regulator using AC chopper and auxiliary transformer which is series connected with main input. It has many advantages such as fast voltage control, high efficiency and low THD. A detail study of step down AC voltage regulator is described and two kinds of novel step-up/down voltage regulator for AVR are proposed. The operation principle and PWM method of the proposed regulator are described. Experimental results show that it can be used as AC voltage regulator for special purpose very efficiently.

• Journal of Industrial Technology
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• v.28 no.B
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• pp.167-174
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• 2008

In this paper, the analysis on type effect of inverter output voltage distortion on the control of an induction motor is discussed. The inverter output voltage is distorted differently from the reference voltage owing to the inverter nonlinear characteristic. The inverter nonlinear characteristic results from the voltage drop, the inherent characteristic of the power semiconductor, and the dead time for preventing the short circuit of the inverter leg. This characteristic distorts the inverter output voltage and then, causes the motor flux estimation error. Although this characteristics do not significantly effect in the general-purpose induction motor control, but significantly effect on the low-speed operation of high performance motor control such as the sensorless vector control.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.11
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• pp.994-999
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• 2006

For low-cost embedded EEPROM, in this paper, single polysilicon EEPROM and n-channel high-voltage LDMOST device are developed in a $0.25{\mu}m$ standard CMOS logic process. Using these devices developed, the EEPROM chip is fabricated. The fabricated EEPROM chip is composed of 1 Kbit single polysilicon EEPROM away and high voltage driver circuits. The program and erase characteristics of the fabricated EEPROM chip are evaluated using 'STA-EL421C'. The fabricated n-channel high-voltage LDMOST device operation voltage is over 10 V and threshold voltage window between program and erase states of the memory cell is about 2.0 V.

• Journal of Aerospace System Engineering
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• v.1 no.2
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• pp.21-26
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• 2007

DMFC(Direct Methanol Fuel Cell) has been considered as an attractive option to produce electric power in many application. In this study, in order to estimate the effects of the methanol concentration, wind velocity and temperature on the performance of DMFC, a physical prototype of DMFC was designed and manufactured, and the stack voltage of DMFC was measured during the operation of DMFC. Expecially, the experimental results showed that a low stack temperature, a low wind velocity and an excess methanol concentration lead to the increase of the time to reach the maximum stack voltage.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.948-950
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• 2003

In this literature, the CMOS current mode fout quadrant differentiator circuit is proposed. The implementation is base on an appropriate input stage that converts the input current into a compressed voltage at the input capacitor ($C_{gs}$) of the CMOS driver circuit. This input voltage use as the control output current which flow to the output node by passing through a MOS active load and use it as the feedback voltage to the input node. Simulation results with level 49 CMOS model of MOSIS are given to demonstrate the correct operation of the proposed configuration. But the gain of the circuit is too low so the output differentiate current also low. The proposed differentiator is expected to find several applications in analog signal processing system.