• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.119-119
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• 2008

The electrical characteristics of Metal-Ferroelectric-Nitride-Oxide-Silicon (MFNOS) structure is studied and compared to the conventional Silicon-Oixde-Nitride-Oxide-Silicon (SONOS) capacitor. The ferroelectric blocking layer is SrBiNbO (SBN with Sr/Bi ratio 1-x/2+x) with the thickness of 200 nm and is fabricated by the RF sputter. The memory windows of MFNOS and SONOS capacitors with sweep voltage from +10 V to -10 V are 6.9 V and 5.9 V, respectively. The effect of ferroelectric blocking layer and charge trapping on the memory window was discussed. The retention of MFNOS capacitor also shows the 10-years and longer retention time than that of the SONOS capacitor. The better retention properties of the MFNOS capacitor may be attributed to the charge holding effect by the polarization of ferroelectric layer.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.8
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• pp.20-29
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• 2011

This paper presents an improved phase-shift pulse-width modulation (PWM) full-bridge converter using a blocking capacitor. As the proposed converter reduces the circulation energy by inserting only one series blocking capacitor at the primary side of the conventional phase-shift PWM full-bridge converter structure, it improves the operation characteristics of the conventional converter. In this paper, first, the operation of conventional phase-shift PWM full-bridge converter is roughly reviewed, and then the operational principle of the proposed converter is classified and explained by each mode. After that, a prototype design example based on the operational principle is shown. Then, the improved operation characteristics of the proposed converter are actually verified through the experimental results.

• Journal of Power Electronics
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• v.7 no.2
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• pp.118-123
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• 2007

This paper presents a new ZCS-PWM high frequency inverter. Zero current switching operation is achieved in the whole load range by using a simple auxiliary reverse blocking switch in parallel with series resonant capacitor. Dual duty cycle control scheme is used to provide a wide range of high frequency AC output power regulation that is important in many high frequency inverter applications. It found that a complete soft switching operation can be achieved even for low power setting ranges by introducing high-frequency dual duty cycle control scheme. The proposed high frequency inverter is more suitable for consumer induction heating(IH) applications. The operation and control principle of the proposed high frequency inverter are described and verified through simulated results.

• Proceedings of the KIEE Conference
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• 2006.10d
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• pp.129-131
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• 2006

This paper presents a new ZVS-PWM high frequency inverter. The ZVS operation is achieved in the whole load range by using a simple auxiliary reverse blocking switch in parallel with series resonant capacitor. The operating principle and the operating characteristics of the new high frequency circuit treated here are illustrated and evaluated on the basis of simulation results. It was examined that the complete soft switching operation can be achieved even for low power setting ranges by introducing the high frequency dual duty cycle control scheme. In the proposed high frequency inverter treated here, the dual mode pulse modulation control strategy of the asymmetrical PWM in the higher power setting ranges and the lower power setting ones, the output power of this high frequency inverter could introduce in order to extend soft switching operation ranges. Dual duty cycle is used to provide a wide range of output power regulation that is important in many high frequency inverter applications. It is more suitable for induction heating applications the operation and control principle of the proposed high frequency inverter are described and verified through simulated results.

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.4
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• pp.261-268
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• 2020

Transformer saturation in full bridge (FB) isolated DC-DC converters is caused by uneven switching speeds and voltage drops in semiconductor devices and mismatched gate signals. In order to prevent transformer saturation, most popular and widely used approach is to insert a capacitor in series with the transformer windings. This study conducts extensive analyses on transformer saturation and the effect of DC blocking capacitors when they are placed in the primary or secondary windings of a transformer. The effect of the DC blocking capacitors is verified in voltage-fed and current-fed FB converters.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.288-292
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• 2002

We propose the new type of on-chip ESD protection method for RF applications. By using the properties of RF circuits, we can use the short-circuited stub as ESD protection device in front of the DC blocking capacitor Specially, we can use short-circuited stub as the portion of the matching circuit so to reduce the and various parameters of the transmission line. This new type ESD protection method is very different from the conventional ESD protection method. With the new type ESD protection method, we remove the parasitic capacitance of ESD protection device which degrade the performance of core circuit.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.364-367
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• 2001

ZVS Full-bridge converter is widely used in medium power level(1-3kW). ZVS can be designed within a limited load range and ZVS failure at light load condition is assumed to be acceptable within the given efficiency and thermal constraints. However, unbalanced ZVS resonant energy caused by dc blocking capacitor may alleviate the switching loss problem at light load condition. ZVS resonant energy is unbalanced by do blocking capacitor. This problem causes loss and heat concentration of a switch leg, In this paper, this problem is analyzed, and a novel control method is proposed to solve the problem.

• Journal of Electrical Engineering and Technology
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• v.12 no.5
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• pp.1902-1915
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• 2017

This paper presents the evaluation of a three-phase three-level DC-DC converter which achieves the soft switching condition for all switches in the circuit and uses the phase-shift PWM strategy to adjust electric power at the output side. According to the analysis, the operation modes can be categorized into two cases: in the first case, where the phase shift angle is less than 120 degrees and in the second case, where the phase shift angle is more than 120 degrees. The outer switches of the circuit operate under ZVS condition and the inner switches operate under ZVZCS condition. It has been discovered that under ZCS condition of the inner switches, when the blocking capacitors decrease, they make the voltage across the blocking capacitor higher so the current reduce rapidly. A three-phase three-level DC-DC converter has a maximum efficiency of 93.5% when its load is of 5.7 kW. The results from the experiment have been compared to the results obtained by the $MATLAB^{(R)}$ simulator in order to confirm the validity of the proposed converter.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.388-388
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• 2012

In this letter, We have investigated cell characteristics of the alloy FePt-NDs charge trapping memory capacitors with high-k $Al_2O_3$ dielectrics as a blocking oxide. The capacitance versus voltage (C-V) curves obtained from a representative MOS capacitor embedded with FePt-NDs synthesized by the post deposition annealing (PDA) treatment process exhibit the window of flat-band voltage shift, which indicates the presence of charge storages in the FePt-NDs. It is shown that NDs memory with high-k $Al_2O_3$ as a blocking oxide has performance in large memory window and low leakage current when the diameter of ND is below 2 nm. Moreover, high-k $Al_2O_3$ as a blocking oxide increases the electric field across the tunnel oxide, while reducing the electric field across the blocking layer. From this result, this device can achieve lower P/E voltage and lower leakage current. As a result, a FePt-NDs device with high-k $Al_2O_3$ as a blocking oxide obtained a~7V reduction in the programming voltages with 7.8 V memory.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.188-189
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• 2017

There has been a growing demand for power semiconductor switches equipped with high-voltage blocking capability of kV range and fast-switching characteristics of ns range in various plasma application. This paper investigates the application of SiC MOSFETs in the particular plasma application which requires the blocking voltage of 4.5kV and the switching transient time of less than 100ns. In order to meet the required blocking voltage, the series connection of multiple SiC MOSFETs is adopted in this paper. Also, snubber capacitors are employed to equalize the voltage sharing among the series connected SiC MOSFETs. The simulation and experimental result successfully verifies the application of SiC MOSFETs and snubber capacitors in the plasma application requiring high-voltage and fast-switching load dynamics.