• Title/Summary/Keyword: solid capacitor

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Design and Implementation of DC Solid-State Circuit Breaker with Easy Charging Capability of Commutation Capacitor (전류 커패시터의 충전이 용이한 DC 반도체 차단기 설계 및 구현)

  • Kim, Jin-Young;Song, Seung-Min;Choi, Seung-soo;Kim, In-Dong;Choi, Sun Kyu
    • Proceedings of the KIPE Conference
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    • 2017.07a
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    • pp.304-305
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    • 2017
  • AC 그리드에 비해 DC 그리드는 전류의 영교차점이 없으므로 사고전류를 신속하게 차단하지 못 한다면 아크나 스파크에 의한 전기화재가 발생하여 큰 피해가 따른다. 본 연구에서는 신속한 차단과 전류 커패시터를 쉽게 충전할 수 있는 구조가 간단한 새로운 DC SSCB를 제안한다. 제안하는 DC SSCB는 단락사고를 모의하여 시뮬레이션 및 실험을 통해 동작특성을 검증한다. 본 논문에서 연구한 DC SSCB는 향후 DC 그리드 시스템의 설계 및 구현에 활용될 것으로 기대된다.

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Improved Memory Characteristics by NH3 Post Annealing for ZrO2 Based Charge Trapping Nonvolatile Memory

  • Tang, Zhenjie;Zhao, Dongqiu;Li, Rong;Zhu, Xinhua
    • Transactions on Electrical and Electronic Materials
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    • v.15 no.1
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    • pp.16-19
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    • 2014
  • Charge trapping nonvolatile memory capacitors with $ZrO_2$ as charge trapping layer were fabricated, and the effects of post annealing atmosphere ($NH_3$ and $N_2$) on their memory storage characteristics were investigated. It was found that the memory windows were improved, after annealing treatment. The memory capacitor after $NH_3$ annealing treatment exhibited the best electrical characteristics, with a 6.8 V memory window, a lower charge loss ~22.3% up to ten years, even at $150^{\circ}C$, and excellent endurance (1.5% memory window degradation). The results are attributed to deep level bulk charge traps, induced by using $NH_3$ annealing.

Design of gate driver and test circuits for solid-state pulsed power modulator (반도체 소자기반 펄스 전원용 게이트 구동 및 시험회로 설계)

  • Gong, Ji-Woong;Ok, Seung-Bok;An, Suk-Ho;Jang, Sung-Roc;Ryoo, Hong-Je
    • Proceedings of the KIPE Conference
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    • 2012.07a
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    • pp.230-231
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    • 2012
  • This paper describes a gate driver that operates numerous semiconductor switch in the solide-state pulsed power modulator. the proposed gate driver is designed to receive both the isolated drive-power and the on/off pulse signals through the transformer. Moreover, the IGBT-switch can be quickly turned off by adding protection circuit. Therefore it protects the IGBT-switch from the arc condition that frequently occurs in high-voltage pulse application. To comprehend operating characteristic of each IGBT-switch in pulse output condition, the device consisting of a high efficiency soft-switching capacitor charger and two series stacking IGBT-switch is developed. Finally, the relability of the proposed gate driver and the device for its test are proved through PSpice simulation and experiments.

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Microstructure Evolution and Dielectric Characteristics of CaCu3Ti4O12 Ceramics with Sn-Substitution

  • Kim, Cheong-Han;Oh, Kyung-Sik;Paek, Yeong-Kyeun
    • Journal of the Korean Ceramic Society
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    • v.50 no.1
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    • pp.87-91
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    • 2013
  • The doping effect of Sn on the microstructure evolution and dielectric properties was studied in $CaCu_3Ti_{4-x}Sn_xO_{12}$ polycrystals. Samples were produced by a conventional solid-state reaction method. Sintering was carried out at $1115^{\circ}C$ for 2-16 h in air. The dielectric constant and loss were examined at room temperature over a frequency range between $10^2$ and $10^6$ Hz. The microstructure was found to evolve into three stages. Addition of $SnO_2$ led to an increase in density and advanced formation of abnormal grains. The formation of coarse grains with a reduced thickness of the boundary brought about an enhanced dielectric constant and a lower dielectric loss below ~1 kHz. EDS data showed the Cu-rich phase along the grain boundary, which should contribute to the improved dielectric constant according to the internal barrier layer capacitor model. After all, $SnO_2$ was an effective dopant to elevate the dielectric characteristics of $CaCu_3Ti_{4-x}Sn_xO_{12}$ polycrystals as a promoter for abnormal grain growth.

Dielectric and Electric Properties of Mutilayer Ceramic Capacitor with SL Temperature Characteristics (SL 온도특성을 가지는 적층 칩 세라믹 캐패시터용 유전체의 유전 및 전기적 특성)

  • Yoon, Jung-Rag;Lee, Sang-Won;Kim, Min-Ki;Lee, Kyoung-Min
    • 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.

The Piezoelectric Properties of (Na0.5K0.5)NbO3-K5.4Cu1.3Ta10O29 Ceramics with Various K5.4Cu1.3Ta10O29 Doping and Sintering Temperatures

  • Yoon, Jung Rag;Lee, Chang-Bae;Lee, Serk Won;Lee, Heun-Young
    • Transactions on Electrical and Electronic Materials
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    • v.13 no.6
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    • pp.283-286
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    • 2012
  • (1-X)$(Na_{0.5}K_{0.5})NbO_3-XK_{5.4}Cu_{1.3}Ta_{10}O_{29}$ (NKN-KCT) lead-free piezoelectric ceramics have been synthesized by the conventional solid state sintering method, and their sinterability and piezoelectric properties were investigated. Typically, this material is sintered between 1,025 and $1,100^{\circ}C$ for 2 hours to achieve the required densification. Crystalline structures and Microstructures were analyzed by X-ray diffraction and scanning electron microscope. The density, dielectric constant (${\varepsilon}_r$), piezoelectric constant $d_{33}$, electromechanical coupling factor $k_p$ and mechanical quality factor $Q_m$ value of the NKN ceramics depended upon the KCT content and the sintering temperature. In particular, the KCT addition to NKN greatly improved the mechanical quality factor $Q_m$ value. The ceramic with X = 1.0 mol% sintered at $1,050^{\circ}C$ exhibited optimum properties (${\varepsilon}_r$=246, $d_{33}$=95, $k_p$=0.38 and $Q_m$=1,826). These results indicate that the ceramic is a promising candidate material for applications in lead free piezoelectric transformer and filter materials.

A Study on the Synthesis and Consolidation of Ti3Al by Electro-Discharge (전기방전에 의한 Ti3Al의 합성 및 소결 특성 연구)

  • Jang, Hyungsun;Cho, Yujung;Kang, Taeju;Kim, Kibeom;Lee, Wonhee
    • Korean Journal of Metals and Materials
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    • v.47 no.8
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    • pp.488-493
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    • 2009
  • Direct syntheses of bulk $Ti_3Al$ via electro-discharge-sintering (EDS) of a stoichiometric elemental powder mixture were investigated. A capacitor bank of $450{\mu}F$ was charged with three input energies, 0.5, 1.0, and 1.5 kJ. The charged capacitor bank was then instantaneously discharged through 0.3 g of a Ti-25.0 at.%Al powder mixture for consolidation. Complete phase transformation occurred in less than $200{\mu}sec$ by the discharge and a bulk $Ti_3Al$ compact was obtained. Compared with consolidated samples fabricated by conventional methods such as high vacuum sintering and casting, the electro-discharge-sintered $Ti_3Al$ compact shows a very fine microstructure with a hardness value of 425 Hv. Electro-discharge-sintering under a $N_2$ atmosphere successfully modified the surface Ti oxide of the $Ti_3Al$ compact into Ti nitride, which concurred with the synthesis and consolidation of $Ti_3Al$. Complete conversion yielding a single phase $Ti_3Al$ is primarily dominated by the fast solid state diffusion reaction.

Synthesis of Titanium Silicide by Electro-Discharge-Sintering of Ti and Si Powder Mixture (Ti 및 Si 혼합 분말의 전기방전소결에 의한 Titanium Silicide의 합성 연구)

  • Cheon Y. W.;Oh N. H.;Kim Y. H.;Byun C. S.;Lee S. H.;Lee W. H.
    • Journal of Powder Materials
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    • v.12 no.6 s.53
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    • pp.447-452
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    • 2005
  • The synthesis and consolidation of titanium silicide by electro-discharge-sintering has been investigated. As-received Ti powder was in flaky shape and the mean particle size was $45.0{\mu}m$, whereas the mean particle size of the pre-milled Si powder with angular shape was $8.0{\mu}m$. Single pulse of 2.5 to 5.0 kJ/0.34g-elemental Ti and pre-milled Si powder mixture with the composition of $Ti-37.5at.\%$ Si was applied using $300{\mu}F$ capacitor. The solid with $Ti_5Si_3$ phase has been successfully fabricated by the discharge with the input energy more than 2.5kJ in less than $129{\mu}sec.$ Hv values were found to be higher than $1000kgf/mm^2$. The formation of $Ti_5Si_3$ occurred through a fast solid state diffusion reaction.

A Study of Electro-Discharge-Sintering of Ti-6Al-4V Spherical Powders Doped with Hydroxyapatite by Spex Milling and Its Consolidation Characteristics (Hydroxyapatite가 도핑된 Ti-6Al-4V 구형 분말의 전기방전 소결 및 소결체 특성에 관한 연구)

  • Cho, Y.J.;Kim, Y.H.;Jo, Y.H.;Kim, M.J.;Kim, H.S.;Kim, S.W.;Park, J.H.;Lee, W.H.
    • Journal of Powder Materials
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    • v.20 no.5
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    • pp.376-381
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    • 2013
  • Spherical Ti-6Al-4V powders in the size range of 250 and 300 ${\mu}m$ were uniformly doped with nano-sized hydroxyapatite (HAp) powders by Spex milling process. A single pulse of 0.75-2.0 kJ/0.7 g of the Ti-6Al-4V powders doped with HAp from 300 mF capacitor was applied to produce fully porous and porous-surfaced Ti-6Al-4V implant compact by electro-discharge-sintering (EDS). The solid core was automatically formed in the center of the compact after discharge and porous layer consisted of particles connected in three dimensions by necks. The solid core increased with an increase in input energy. The compressive yield strength was in a range of 41 to 215 MPa and significantly depended on input energy. X-ray photoelectron spectroscopy and energy dispersive x-ray spectrometer were used to investigate the surface characteristics of the Ti-6Al-4V compact. Ti and O were the main constituents, with smaller amount of Ca and P. It was thus concluded that the porous-surfaced Ti-6Al-4V implant compacts doped with HAp can be efficiently produced by manipulating the milling and electro-discharge-sintering processes.

Fabrication of Niobium Powder for Solid-electrolyte Capacitors (고체 전해커패시터용 니오븀 분말제조)

  • Yoon, Jae-Sik;Hwang, Sun-Ho;Kim, Byung-Il
    • Journal of the Korean institute of surface engineering
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    • v.42 no.5
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    • pp.227-231
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    • 2009
  • The niobium capacitor showed somewhat more unstable characteristics than the commercial tantalum capacitors, but is nonetheless considered applicable as a future substitute for tantalum capacitors. In this study, niobium powder was fabricated by metallothermic reduction process using $K_2NbF_7$ as the raw materials, KCl and KF as the diluents and Na as the reducing agent. The niobium particle size greatly decreased from 0.7um to 0.2 um as the amount of diluent increased. However if a higher surface area of powder is required, more diluents need to be used in the said method in order to produce niobium powder. The niobium powder morphology and particle size are very sensitive to a amount of sodium excess. The particle size of niobium powder increased with a increasing amount of sodium excess. When more diluent and sodium are used, the niobium powder will be contaminated with more impurities such as Fe, Cr, Ni so on.