• Journal of Electrical Engineering and Technology
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• v.8 no.6
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• pp.1283-1295
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• 2013

This study proposed an improvement in synchronously rotating reference frame-based voltage sag detection under distorted grid voltages. In the past, the conventional synchronously rotating reference frame (CSRRF)-based voltage sag detection was generally used in the voltage sag compensation applications. Its disadvantage is a long delay of detection time. The modified synchronously rotating reference frame (MSRRF)-based voltage sag detection is able to detect the voltage sag with only a short delay in detection time. However, its operation under distorted grid voltage conditions is unavailable. This paper proposed the improvement of modified synchronously rotating reference frame (IMSRRF)-based voltage sag detection for use in distorted grid voltages with very fast operation of voltage sag detection. The operation of the proposed voltage sag detections is investigated via simulations and experimentations to verify the performance of the IMSRRF-based voltage sag detection.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.5
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• pp.753-756
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• 2012

In this paper, a modified low-votlage CMOS bandgap voltage reference with CTAT compensation is presented. The proposed structure doesn't use PTAT current. The proposed structure is more simple than the existing structure and doesn't use the eighteen BJT. The modified low-votlage CMOS bandgap voltage reference with CTAT compensation has been successfully verified in a standard 0.18um CMOS process. The simulation results have confirmed that, with the minimum supply voltage of 1.25V, the output reference voltage at 549mV has a temperature coefficient of 12$ppm/^{\circ}C$ from $0^{\circ}C$ to $100^{\circ}C$.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.8 no.3
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• pp.152-156
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• 2009

This paper designs and implements wake up module for WBAN/USN sensor node which is using dynamic reference voltage demodulation circuit. When a comparator is used in a system for detecting received voltage level, comparator must have a reference voltage. However, the reference voltage is fixed, the system can communicate only a few range because received voltage level is changing widely due to distance of the wireless sensor nodes. Therefore, the proposed wake up module employs a dynamic reference voltage demodulation circuit for increasing communication range.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.1239-1243
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• 2004

A novel voltage-current reference circuit for stable voltage-current applications is Proposed. Circuits for a positive and for a negative voltage-current reference are presented and are designed with commercial CMOS technology. The voltage-current reference that is stable over ambient temperature variations is an important component of most data acquisition systems. These results are verified by the HSPICE simulation $0.8{\mu}m$ parameter. As the result, the temperature dependency of output voltage and output current each is $0.57mV/^{\circ}C$, $0.11{\mu}A/^{\circ}C$ and the power dissipation is 1.8 mV on 5V supply voltage.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.375-378
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• 2013

A reference voltage generator which is insensitive to PVT (process-voltage-temperature) variation necessary for NVM memory IPs such as EEPROM and MTP memories is designed in this paper. The designed BGR (bandgap reference voltage) circuit based on MagnaChip's $0.18{\mu}m$ EEPROM process uses a low-voltage bandgap reference voltage generator of cascode current-mirror type with a wide swing and shows a reference voltage characteristic insensitive to PVT variation. The minimum operating voltage is 1.43V and the VREF sensitivity against VDD variation is 0.064mV/V. Also, the VREF sensitivity against temperature variation is $20.5ppm/^{\circ}C$. The VREF voltage has a mean of 1.181V and its three sigma ($3{\sigma}$) value is 71.7mV.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.9
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• pp.1651-1655
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• 2011

The reference impedances which is about 95% supply impedance value of residential consumers' supply impedances was published by IEC in 1980. The reference impedances are the standard values for use in determining the voltage disturbance characteristics of electrical equipment like the flicker. In IEC 60725, the reference impedances for premises having service current capacities less than 100A per phase and for service current capacities more than 100A per phase are recommended. And these reference impedances are targeted for the countries using 50Hz power frequency. Because of the frequency difference, the reactance values of the reference impedances will be increased in 60Hz power system like Korea, And also the reference impedances are different significantly each other according to declared voltage variation, power consumption and service wire length etc. Therefore It is needed to calculate the reference impedances suitable for domestic low-voltage power system. In this paper, the reference impedances for service current capacities less than 100A in 220/380V, 60Hz single-phase two wire and three-phase four wire low-voltage system are calculated, And the equations for service current capacities more than 100A to calculate the modulus value of maximum supply impedances are suggested base on IEC 60725 and the reference impedances for those are calculated on service current of 100A per phase.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.785-788
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• 2007

The newly proposed badgap reference voltage generator is insensible to PVT(process, voltage, temperature) variation and has a lower minimum supply voltage, which is required for stable operation. The simulation result is that the bandgap reference voltage generator starts operation at 1.0V of supply voltage. The layout of the bandgap reference voltage generator is designed using Magnachip $0.18{\mu}m$ DDI process, and the size is $409.36{\mu}m$ ${\times}$ $435.46{\mu}m$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.05b
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• pp.46-49
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• 2005

This paper presents the electrical characteristics of metal oxide varistors for lightning surge arresters. ZnO varistors were fabricated with typical ceramic production methods and two types of varistors were also prepared to be compared. The nominal discharge current and line discharge class of those varistors are $10kA(8/20{\mu}s)$ and class 3, respectively. The diameter of varistors manufactured and prepared were in the range of 61.6~65.0mm and the thickness of those were in the range of 27~42.52mm. The reference and residual voltage were tested and reference and residual voltage per 1mm and the ratio of reference and residual voltage were calculated. The reference voltage per 1mm of varistors manufactured was about 175V/mm but that of A's and B's varistors was nearly 200V/mm. The residual voltage exhibited the same trends as the reference voltage, so the reference and residual voltage per 1mm of domestic varistors should be increased. According to the results of tests, it is thought that if the reference and residual voltage per 1mm were increased to 200V/mm and 330V/mm, domestic ZnO varistors would be possible to apply to the station class arresters in the near future.

• Journal of the Semiconductor & Display Technology
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• v.17 no.2
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• pp.53-56
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• 2018

In this paper, a CMOS bandgap voltage reference that is not sensitive to changes in the external environment is presented. Large OLED display panels need high supply voltage. MOSFET devices with high voltage are sensitive to the output voltage due to the channel length modulation effect. The self-cascode circuit was applied to the bandgap reference circuit. Simulation results show that the maximum output voltage change of the basic circuit is 77mV when the supply voltage is changed from 10.5V to 13.5V, but the proposed circuit change is improved to 0.0422mV. The improved circuit has a low temperature coefficient of $9.1ppm/^{\circ}C$ when changing the temperature from $-40^{\circ}C$ to $140^{\circ}C$. Therefore, the proposed circuit can be used as a reference voltage source for circuits that require a high supply voltage.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.5
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• pp.249-257
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• 2002

In this paper, a novel control scheme compensating source voltage unbalance and harmonic currents for the combined system of series active and shunt passive power filter is proposed, where no low/high-pass filters are used in deriving the reference voltage for compensation. The phase angle and the reference voltages compensating for harmonic current and unbalanced voltage are derived from the positive sequence component of the unbalanced voltage set, which is simply obtained by using digital all-pass filters. In order to remove the phase delay in generating the reference voltage for compensation, the reference of 5th and 7th harmonic components is predicted one-sampling ahead. The validity of the proposed scheme has been verified for 3[kVA] proto-type active power filter system.