• Korean Journal of Materials Research
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• v.3 no.4
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• pp.352-360
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• 1993

A nitride layer was df'posited on the thermal oxide layer by LPCVD process. ONO(oxidenitricle oxide) capacitors with various thickness of component layer wore fabricated by wet reoxidation of the nitride with and without anrwalmg treatment and their properties were investigated. As a result of observation on the refrative index and etching behavior of the ONO fIlms, the nitride layer OF 40 A thick ness was not so dense that the bottom oxide during the reoxidation process and the capability of securing the capacitance decreased. The conduction current in the ONO multl-Iayer dielctric film was reduced as the bottom(or top) oxide layer became thicker. However, in the case of oxide with thickness more than 50A, it merely plays a factor of reduction in capacitance, and the effect of barrier for hole injection was not so much increased. Annealing of the nitride laypr bpfore reoxidation did not show a grpat effects on the refractive index and capacitance of the film, however, the annealing process increased the breakdown voltage by 2${\cdot}$V.

• Korean Journal of Materials Research
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• v.19 no.10
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• pp.544-549
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• 2009

Activated carbon (AC) with very large surface area has high capacitance per weight. However, such activation methods tend to suffer from low yields, below 50%, and are low in electrode density and capacitance per volume. Carbon NanoFibers (CNFs) had high surface area polarizability, high electrical conductivity and chemical stability, as well as extremely high mechanical strength and modulus, which make them an important material for electrochemical capacitors. The electrochemical properties of immobilized CNF electrodes were studied for use as in electrical double layer capacitor (EDLC) applications. Immobilized CNFs on Ni foam grown by thermal chemical vapor deposition (CVD) were successfully fabricated. CNFs had a uniform diameter range from 50 to 60 nm. Surface area was 56 m$^2$/g. CNF electrodes were compared with AC and multi wall carbon nanotube (MWNT) electrodes. The electrochemical performance of the various electrodes was examined with aqueous electrolyte of 2M KOH. Equivalent series resistance (ESR) of the CNF electrodes was lower than that of AC and MWNT electrodes. The specific capacitance of 47.5 F/g of the CNF electrodes was achieved with discharge current density of 1 mA/cm$^2$.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.1
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• pp.1-8
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• 2010

The ultrafashionable machinery that require high quality electricity power has been daily come into being. Because domestic power system has been larger and more complicated in accordance with raising power demand by power market requirement. Because of these power market situations, The FACTS (Flexible AC Transmission System) which is power transmission system for the next generation to meet flexible supply the power and reliability has been applied. If they, compensators and FACTS, are used inter-efficiently in range that does not affect the stability and a badly influence the security, they might be increase in the voltage stability of system, supply reliability and also achieve the voltage control in a suddenly changed power system. Therefore we describe and suggest on this treatise that a plan for coordination control between UPFC, Shunt elements (Sh. Capacitors & Sh. Reactors) among compensators and also describe the method to keep or control the voltage of power system in allowable ranges. The method follows that, we used characteristics of each equipment, UPFC would be also settled to keep the identified voltage range in change of load bus, Shunt elements also would be settled to supply the reactive power shortage in out of operating range of UPFC to cope actively with change of the power system. As the result of simulation, it is possible to keep the load bus voltage in limited range in spite of broad load range condition. This helps greatly for the improvements of supply reliability and voltage stability.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.7
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• pp.645-651
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• 2008

To reduce noise in high frequency and distortion of signal, the composition of $(Ca_{0.7}Sr_{0.3})(Zr_{0.97}Ti_{0.03})O_3$ and $(Ba_{0.2}Ca_{0.4}Sr_{0.4})TiO_3$ was developed. The composition was not solid solution, but mixtures of various phases composed of Ca, Sr, Zr, Ti and Ba oxides. The dielectric constant increased, the quality factor and the insulation resistance decreased with $(Ba_{0.2}Ca_{0.4}Sr_{0.4})TiO_3$ content. The composition of $0.4(Ba_{0.2}Ca_{0.4}Sr_{0.4})TiO_3$ satisfied the electric characteristics and the temperature coefficient of dielectric constant (TCC). In addition, the glass frit and $MnO_2$ also affected the electric characteristics. From the result of the best fit simulation, $MnO_2$ 0.3 mol%, the glass frit 0.6 wt% showed the insulation resistance $906{\Omega}{\cdot}F$, the quality factor 821, and the dielectric constant 92. With the selected composition, MLCC capacitors sized $4.5{\times}3.2{\times}2.5mm$ were manufactured with 105 layered of the dielectric thickness $16{\mu}m$ using Ni inner electrode, They represented the capacitance $98{\sim}102$ nF, the quality factor 1,200 and the insulation resistance $1,500{\Omega}{\cdot}F$. Also, they had high break-down voltage with $107{\sim}115V/{\mu}m$, and satisfied the SL TCC characteristics.

• Transactions on Electrical and Electronic Materials
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• v.17 no.5
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• pp.261-269
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• 2016

A high-performance transmit/receive (T/R) switch is essential for every radio-frequency (RF) device. This paper proposes a T/R switch that is designed in the CEDEC 0.13 μm complementary metal-oxide-semiconductor (CMOS) technology for 2.4 GHz ISM-band RF applications. The switch exhibits a 1 dB insertion loss, a 28.6 dB isolation, and a 35.8 dBm power-handling capacity in the transmit mode; meanwhile, for the 1.8 V/0 V control voltages, a 1.1 dB insertion loss and a 19.4 dB isolation were exhibited with an extremely-low power dissipation of 377.14 μW in the receive mode. Besides, the variations of the insertion loss and the isolation of the switch for a temperature change from - 25℃ to 125℃ are 0.019 dB and 0.095 dB, respectively. To obtain a lucrative performance, an active inductor-based resonant circuit, body floating, a transistor W/L optimization, and an isolated CMOS structure were adopted for the switch design. Further, due to the avoidance of bulky inductors and capacitors, a very small chip size of 0.0207 mm² that is the lowest-ever reported chip area for this frequency band was achieved.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.3
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• pp.224-230
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• 2016

In this study, a single-power-conversion series-resonant ac-dc converter with high efficiency and high power factor is proposed. The proposed ac-dc converter consists of single-ended primary-inductor converter with an active-clamp circuit and a voltage doubler with series-resonant circuit. The active-clamp circuit clamps the surge voltage and provides zero-voltage switching of the main switch. The series-resonant circuit consists of leakage inductance $L_{lk}$ of the transformer and resonant capacitors $ C_{r1}$ and $ C_{r2}$. This circuit also provides zero-current switching of output diodes $D_1$ and $D_2$. Thus, the switching loss of switches and reverse-recovery loss of output diodes are considerably reduced. The proposed ac-dc converter also achieves high power factor using the proposed control algorithm without the addition of a power factor correction circuit and a dc-link electrolytic capacitor. A detailed theoretical analysis and the experimental results for a 1kW prototype are discussed.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.113.1-113.1
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• 2011

PEMS (printed electro-mechanical system) is fabricated by means of various printing technologies. Passive and active compo-nents in 2D or 3D such as conducting lines, resistors, capacitors, inductors and TFT(Thin Film Transistor), which are printed withfunctional materials, can be classified in this category. And the issue of PEMS is applied to a R2R process in the manu-facturing process. In many electro-devices, the vacuum process is used as the manufacturing process. However, the vacuum process has a problem, it is difficult to apply to a continuous process such as a R2R(roll to roll) printing process. In this paper, we propose an ESD (electro static deposition) printing process has been used to apply an organic solar cell of thin film forming. ESD is a method of liquid atomization by electrical forces, an electrostatic atomizer sprays micro-drops from the solution injected into the capillary with electrostatic force generated by electric potential of about several tens kV. ESD method is usable in the thin film coating process of organic materials and continuous process as a R2R manufacturing process. Therefore, we experiment the thin films forming of PEDOT:PSS layer and active layer which consist of the P3HT:PCBM. The organic solar cell based on a P3HT/PCBM active layer and a PEDOT:PSS electron blocking layer prepared from ESD method shows solar-to-electrical conversion efficiency of 1.42% at AM 1.5G 1sun light illumination, while 1.86% efficiency is observed when the ESD deposition of P3HT/PCBM is performed on a spin-coated PEDOT:PSS layer.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.3
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• pp.206-212
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• 2017

Induction motor torque is the reactive power is needed which corresponds to the exciting current to generate the magnetic flux as the product of current and flux. For use in the method of supplying the required reactive power to the induction motor power factor correction apparatus using a lot of ways to supply in place of the power supply side, when using a power factor compensation device can reduce the apparent power, the power factor can be improved. However, the distance to the emergency generator transformers or motors from the motor capacity is smaller but short and difficult to maneuver the theory and practice of the operating characteristics of the starting characteristics of the motor used a lot of large industrial plants were measured and analyzed. Therefore, this study investigated the motor starting Analysis and interpretation for the relationship with the large motor starting torque and speed during motor starting.

• Journal of Advanced Navigation Technology
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• v.19 no.5
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• pp.433-439
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• 2015

Recently, Interest in power the quality was increased because of increasing the use of sensitive load equipment into an electrical disturbance such as computer, Electricity, Electronics, Telecommunications and semiconductor device. In addition, To enhance power quality, the instantaneous voltage drop occurred in precision load equipment is a need for proper compensation. In order to solve the problem, The developed dynamic voltage restorer (DVR) using an electric double layer capacitor (EDLC) has been applied. In this paper, We will do study to apply hybrid capacitors that have high energy density to the same size compared to the EDLC to DVR. Also, As a emergency luminaires of emergency power supply that we can support more than 10 years of life was confirmed the applicability of hybrid capacitor.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.3
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• pp.2301-2307
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• 2015

The aim of this study was to evaluate the feasibility of application of the high voltage impulse (HVI) technique to the control of scale formation by calcium carbonate, which is pointed out as an important issue in industrial water treatment. The HVI system consisted of the power supply, high voltage generator, capacitors, switch and impulse generator was designed and made in laboratory scale, which can make 17kV impulse. HVI was introduced to the reactor that was filled with synthetic water containing $Ca^{2+}$ion. The concentration of calcium ion decreased only 3.0% after 5 minutes of contact time. However, it decreased up to 13.7% after 60 minutes of HVI contact time. Temperature and pH increased but conductivity decreased due to precipitation of the calcium carbonate. Although the decrease in concentration of calcium ion was not sufficient, it was verified that the HVI technique could be applicable for the softening and desalting processes.