• Transactions on Electrical and Electronic Materials
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• v.12 no.1
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• pp.35-39
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• 2011

An electrically erasable programmable read-only memory (EEPROM) containing a stacked metal-insulator-metal (MIM) and n-well capacitor is proposed. It was fabricated using a 0.18 $\mu$m standard complementary metal-oxide semiconductor process. The depletion capacitance of the n-well region was effectively applied without sacrificing the cell-area and control gate coupling ratio. The device performed very similarly to the MIM capacitor cell regardless of the smaller cell area. This is attributed to the high control gate coupling ratio and capacitance. The erase speed of the proposed EEPROM was faster than that of the cell containing the MIM control gate.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1499-1501
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• 2003

The A $Sr_{0.7}Bi_{2.6}Ta_2O_9$(SBT)thin films are deposited on Pt-coated electrode(Pt/$TiO_2/SiO_2$/Si) using RF magnetron sputtering method. The electrical properties of SBT capacitors with top electrodes were studied. In the XRD pattern, the SBT thin films in all annealing temperatures had (105) orientation. In the SEM images, Bi-layered perovskite phase was crystallized at $750^{\circ}C$ and grains largely grew in oxygen annealing atmosphere. The electrical properties of SBT capacitor with top electrodes represents a favorable properties in Pt electrode. The maxim urn remanent polarization and the coercive electric field with Pt electrode are $12.40C/cm^2$and 30kV/cm respectively. The dielectric constant and leakage current density with Pt electrode is 340 and $6.8110^{-10}A/cm^2$ respectively.

• Proceedings of the KIEE Conference
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• 2004.11a
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• pp.183-186
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• 2004

The metal-ferroelectric-insulator-semiconductor(MFIS) capacitors were fabricated using a metalorganic decomposition (MOD)method. The $CeO_2$ thin films were deposited as a buffer layer on Si substrate and $Bi_{3.25}La_{0.75}Ti_3O_{12}$ (BLT) thin films were used as a ferroelectric layer. The electrical and structural properties of the MFIS structure were investigated by varying the $CeO_2$ layer thickness. The width of the memory window in the capacitance-voltage (C-V)curves for the MFIS structure decreased with increasing thickness of the $CeO_2$ layer. Auger electron spectroscopy (AES) and transmission electron microscopy (TEM) show no interdiffusion by using the $CeO_2$ film as buffer layer between the BLT film and Si substrate. The experimental results show that the BLT-based MFIS structure is suitable for non-volatile memory field-effect-transistors (FETs) with large memory window.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.193-196
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• 2001

This paper describes an improved short-circuit protection for a multilevel ac/dc power converter The output do power of the proposed converter can be disconnected from the load within several hundred microseconds at the instant of short-circuit fault. Once the fault has been cleared the dc power is reapplied to the load. The rising time of the do load voltage is as small as several hundred microseconds, and there is no overshoot of the dc voltage because the do output capacitors hold undischarged state. Therefore, the proposed converter can be used for a power supply, which requires a rapid disconnection of the load from the power supply in the case of a short circuit, as well as a rapid connection the load to the power supply after the clearance of the short circuit condition.

• Journal of Surface Science and Engineering
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• v.49 no.2
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• pp.191-195
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• 2016

Among the lithium metal oxides for hybrid-capacity, $Li_4Ti_5O_{12}(LTO)$ is an emerging electrode material as zero-stain material in volume change during the with the charging and discharging processes. However, LTO has a limitation of low ionic and electronic conductivity. To enhance the ionic and electronic properties of $Li_4Ti_5O_{12}(LTO)$, we synthesized the spherical LTO/CNT composite by sol-gel process for hybrid capacitors. CNT interconnection networks between CNT-LTO particles enhanced electronic conductivity and electrochemical charging/discharging properties. All of the LTO samples was observed to show the spinel structure and spherical morphology with the diameter of $5{\sim}10{\mu}m$. Especially, spherical LTO/CNT composite of the CNT-3 wt% showed the enhanced capacity from 110 mAh/g to 140 mAh/g at 10 C.

• Journal of Electrical Engineering and Technology
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• v.9 no.2
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• pp.576-588
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• 2014

The superiority of CMI (Cascaded Multilevel Inverter) is unparalleled in high power and high voltage STATCOM (Static Synchronous Compensator). However, the parameters and operating conditions of each individual power unit composing the cascaded STATCOM differ from unit to unit, causing unit voltage disequilibrium on the DC side. This phenomenon seriously impairs the operation performance of STATCOM, and thus maintaining the DC voltage balance and stability becomes critical for cascaded STATCOM. This paper analyzes the case of voltage disequilibrium, combines the operation characteristics of the cascaded STATCOM, and proposes a new DC voltage control scheme with the advantages of good control performance and stability. This hierarchical control method uses software to achieve the total active power control and also uses chopper controllers to enable that the imbalance power can flow among the capacitors in order to keep DC capacitor voltages balance. The operating principle of the chopper controllers is analyzed and the implementation is presented. The major advantages of the proposed control strategy are that the number of PI regulators has been decreased remarkably and accordingly the blindness of system design and debugging also reduces obviously. The simulation reveals that the proposed control scheme can achieve the satisfactory control goals.

• Journal of Electrical Engineering and Technology
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• v.13 no.3
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• pp.1346-1354
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• 2018

Quality of the power system depends upon the reliability of its components such as transformer, transmission lines, insulators, circuit breakers and isolators. The transient voltage due to internal or external reasons may affect the insulation level of the components. The insulation level of these components must be tested against these conditions. Different studies, testing of different electrical components against high voltage impulses and different industrial applications rely on the international manufactures for pulsed power generation and testing, that is quite expensive and large in size. In this paper a model of impulse voltage generator with capacitive load of pin type insulator is studied by simulation method and by an experimental setup. A ten stage high voltage impulse generator (HVIG) is designed and implemented for different applications. In this proposed model, the cost has been reduced by using small and cheap capacitors as an alternative for large and expensive ones while achieving the same effectiveness. Effect of the distributed capacitance in each stage is analyzed to prove the effectiveness of the model. Different values of front and tail resistances have been used to get IEC standard waveforms. Results reveal the effectiveness at reduced cost of the proposed model.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.4
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• pp.8-12
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• 2003

Characteristics of optical transceiver module in radio frequency(RF) band were investigated with TO-can packaged Fabry-Perot laser diode(FP-LD). R-L-C parameters for equivalent circuit model of the LD were extracted with an impedance analyzer. With this model, impedance matching to the packaged LD could be performed by eliminating inductive components of the leads in the package by using lumped chip capacitors that have opposite reactance, while it shows resonance dip in low frequency band. The resonance dip could be removed using lumped elements for impedance matching by shifting the resonance frequency to the region out of interest.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2003.11a
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• pp.283-288
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• 2003

This paper presents the result of survey of case study for Harmonics in electrical Installations of buildings. Recently, many power electronic equipments(power converter, computers, air conditioners electronic ballasts for fluorescent lamps and so on) are used in office buildings, and harmonic current from them influence the other equipments in a distribution line. Notably, voltage distortion or voltage harmonics may approach or exceed is allowable level in power distribution system. Individual electric power consumers and end-users and responsible for reducing current harmonics while companies or utilities are responsible for reducing voltage harmonics at the point of common coupling in distribution system. As for harmonics, which one of the electric power qualities, it becomes important to obtain harmonic voltage/current distribution of the power system precisely because the use of power electronic apparatus in increasing. However, there are some difficulties on evaluating the measured data in comparison with the simulated result. The primary cause was indentitied with the resonance of harmonics form many sources. To suppress harmonics in electrical installations of buildings, one of many methods suggest that resonance frequencies are controlled by modulating the capacities of high-voltage customer's capacitors.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.7
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• pp.41-47
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• 2014

The on-line partial discharge (PD) in stator windings of air-cooled gas turbine (GT) generator (119.2MVA, 13.8kV) is measured and analyzed in this paper. This generator was designed by global vacuum pressure impregnation (VPI). The generator failed two times at top bar (16T) of phase B in the stator slot. Six epoxy-mica capacitors were installed in three phases of GT generator. On-line PD test was performed on GT generator using turbine generator analyzer (TGA). TGA showed that the normalized quantity number (NQN) and the PD magnitude($Q_m$) were high in phase B. Internal discharges were generated in phases A, B and C. The trend analysis of NQN and $Q_m$ value are obtained in order to monitor the insulation condition in GT generator stator windings. Phases A and C were in good condition. But phase B had deteriorated significantly