• Title/Summary/Keyword: interface charge

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The Effect of Neutron Radiation on the Electrical Characteristics of SiC Schottky Diodes (중성자 조사에 따른 SiC Schottky Diode의 전기적 특성 변화)

  • Kim, Sung-Su;Kang, Min-Seok;Cho, Man-Soon;Koo, Sang-Mo
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.27 no.4
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    • pp.199-202
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    • 2014
  • The effect of neutron irradiation on the properties of SiC Schottky Diode has been investigated. SiC Schottky diodes were irradiated under neutron fluences and compared to the reference samples to study the radiation-induced changes in device properties. The condition of neutron irradiation was $3.1{\times}10^{10}$ $n/cm^2$. The current density after irradiation decreased from 12.7 to 0.75 $A/cm^2$. Also, a slight positive shift (${\Delta}V_{th}$= 0.15 V) in threshold voltage from 0.53 to 0.68 V and a positive change (${\Delta}{\Phi}_B$= 0.16 eV) of barrier height from 0.89 to 1.05 eV have been observed by the neutron irradiation, which is attributed to charge damage in the interface between the metal and the SiC layer.

A Review on Nanocomposite Based Electrical Insulations

  • Paramane, Ashish S.;Kumar, K. Sathish
    • Transactions on Electrical and Electronic Materials
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    • v.17 no.5
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    • pp.239-251
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    • 2016
  • The potential of nanocomposites have been drawing the intention of the researchers from energy storage to electrical insulation applications. Nanocomposites are known to improve dielectric properties, such as the increase in dielectric breakdown strength, suppressing the partial discharge (PD) as well as space charge, and prolonging the treeing, etc. In this review, different theories have been established to explain the reactions at the interaction zone of polymer matrix and nanofiller; the characterization methods of nanocomposites are also presented. Furthermore, the remarkable findings in the fields of epoxy, cross-linked polyethylene (XLPE), polypropylene and polyvinyl chloride (PVC) nanocomposites are reviewed. In this study, it was observed that there is lack of comparison between results of lab scale specimens and actual field aged cables. Also, non-standardization of the preparation methods and processing parameters lead to changes in the polymer structure and its surface degradation. However, on the positive side, recent attempt of 250 kV XLPE nanocomposite HVDC cables in service may deliver a promising performance in the coming years. Moreover, materials such as self-healing polymer nanocomposites may emerge as substitutes to traditional insulations.

A study on the improvement of the contact of interface and the prevention of the charge recombination (투명전도성 막의 표면처리를 통한 계면 접촉 향상 및 재결합 방지 연구)

  • Seo, Hyun-Woong;Hong, Ji-Tae;Son, Min-Kyu;Kim, Jin-Kyoung;Shin, In-Young;Kim, Hee-Je
    • Proceedings of the KIEE Conference
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    • 2009.07a
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    • pp.1258_1259
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    • 2009
  • 염료감응형 태양전지 (dye-sensitized solar cell; DSC)는 경제성 한계에 달한 Si 태양전지를 대체할 수 있는 유력한 후보로서, 지금까지 많은 연구개발로 큰 효율향상을 기록했다. 다양한 연구 분야 중에서도, 투명전도성 막과 전해질 층간의 접촉으로 발생하는 전자의 재결합을 막기 위해 삽입하는 compact layer는 ZnO dip-coating, $TiCl_4$ dip-coating, Ti sputtering 등 다양한 제조방법이 제시되었다. 본 연구에서는 $TiCl_4$ 용액을 이용해 spin-coating 방법으로 $TiO_2$ compact layer를 제조하는 시도를 했다. 기존 dip-coating 방법과의 비교를 통해서 본 연구의 spin-coating 방법에 의한 효과를 확인한 결과, standard DSC 대비 33.4%, dip-coating 방법으로 compact layer를 삽입한 DSC 대비 6%의 효율 향상을 기록했다.

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A Study on the Analysis of the Urban Sewer Volume Using the Expert System (전문가기법을 이용한 도시 하수용량 분석에 관한 연구)

  • 이규석;유재용
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.11 no.1
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    • pp.67-75
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    • 1993
  • The urban expansion and the modernization of the urban infrastructure need a new technology to manage the facilities. The sewer management, one of the urban infrastructures, requires geographical information systems(GIS) for this purpose, and can be supported by the expert system. Consequently, non-professionals can use this system conveniently. In this study, the search and retrieving capacity of the relational database management system(DBMS) and the chain topology generator of the vector-based GIS were integrated into the sewer management system together with the expert knowledge. This system can predict the sewer volume charge by the simulation, and automate these procedures. This system is also user-friendly by using the user-interface. Finally, the system was applied to one of the Seoul drainage districts and tested.

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Development of catering system using 3-Tier architectures (3-Tier 구조를 이용한 케이터링 시스템 개발)

  • Kim, Hyeock-Jin
    • Journal of the Korea Computer Industry Society
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    • v.7 no.4
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    • pp.421-426
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    • 2006
  • Because the 3-Tier structure cia share a business logic, the reuse of existing code could be guaranteed Al so tiny and little client application in charge of user interface can he made that it doesn't need plenty of client memory and calculation capability. Catering system that capable of meal material code management autom atic production of requiring quantity, purchase and shipping management menu management, account management was developed for grafting 3-Tire structure technology using database language and ADO(ActiveX Dat a Object). This system improved production in field of school lunch program and saved o(poises. finally, this system is suitable to the service environment of school lunch program and lots of utilizations would be anticipated.

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Nitridation of Thin $SiO_2$ Film ($SiO_2$薄膜의 熱的 窒化)

  • Lee, Yong-Soo;Lee, Yong-Hyun;Sohn, Byung-Ki
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.25 no.11
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    • pp.1323-1328
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    • 1988
  • Thermally grown $SiO_2$ films on silicon have been thermally nitrided in the $NH_3$ gas ambient and their properties have been investigated by analyzing the AES data and the results of the I-V and the C-V measurements. The Auger depth profile show that the nitrogen-rich layers are formed at the nitrided oxide film surface and near the $SiO_2$-Si interface. The higher the nitridation temperature is, the larger the refractive index of nitroxide film is. And the thinner the oxide film to be nitrided for the same nitridation temperature is, the larger the refractive index of nitroxide film is. When thin $SiO_2$ film is thermally nitrided, the I-V characteristics show the Fowler-Nordheim conduction fashion. Flatband voltages of $SiO_2$ films are shifted by nitridation, due to the fixed charge formation.

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Analysis of temperature effects on DC parameters of AlGaAs/GaAs HBT (AlGaAs/GaAs HBT의 DC 파라미터에 미치는 온도영향의 해석)

  • 김득영;박재홍;송정근
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.33A no.12
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    • pp.39-46
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    • 1996
  • In AlGaAs/GaAs HBT the temperature dependence of DC parameters was investigated over the temperature range between 95K and 580K. The temperature dependence of DC parameters depends on the relative contribution of each of the current components suc as emitter-injection-current, base-injection-current, bulk recombination current, interface recombination curretn, thermal generation ecurrent and avalanche current due to impact ionization within the collector space charge layer in a specific temperature. In this paper we investigated the temperature effects on DC parameters such as V$_{BE,ON}$ current gain, input and output characteristics, V$_{CE, OFF}$, R$_{E}$, R$_{C}$ and analyzed the origins, and extracted the qualitativ econditions for a stable HBTs against the temperature variation. Finally, in order to keep HBTs stable with respect to the variation of temperature, the valance-band-energy-discontinuity at emitter-base heterojunction should be large enough to enhance the effect of carrier suppression at a relatively high temperature. In addition the recombination centers, especially around collector junction, should be removed and the area of emitter and collector junction should be identical as well.

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Thermal Management of a Nickel/Metal Hydride Battery (Nickel/Metal Hydride 전지의 열관리기술 개발)

  • Kim, Junbom
    • Applied Chemistry for Engineering
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    • v.8 no.4
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    • pp.667-672
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    • 1997
  • Thermal behavior of high capacity Nickel/Metal hybride battery in analyzed using the NISA software which is based on the three dimensional finite element method. Differential energy balance equation is used for the conduction heat transfer of the battery, while convective heat transfer equation is used for the interface between the battery and air. Heat generation rate and convective heat transfer coefficient are tested as variables to investigate thermal behavior, and the generalized equation for maximum temperature inside the battery is developed. The abrupt rise of the battery temperature due to the quick charge or discharge can be prevented from the use of metallic cooling fin. In addition, temperature augmentation of the battery is negligible when the low thermal conductive and thin insulating material is used outside of the battery case.

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Interface Study of the Intermediate Connectors in Tandem Organic Devices

  • Tang, Jian-Xin;Fung, Man-Keung;Lee, Chun-Sing;Lee, Shuit-Tong
    • Journal of Information Display
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    • v.11 no.1
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    • pp.1-7
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    • 2010
  • The intermediate connectors play crucial roles in the performance of tandem organic light-emitting diodes (OLEDs) because they are required to facilitate charge carrier transport and to guarantee transparency for light transmission and deposition compatibility. Understanding the physical properties of the intermediate connector is not only fundamentally important but is also crucial to developing high-efficiency organic devices with a tandem structure. In this study, several effective intermediate connectors in tandem OLEDs using a doped or non-doped organic p-n heterojunction were systematically investigated by studying their interfacial electronic structures and corresponding device characteristics. The working mechanisms of the intermediate connectors are discussed herein by referring to their relevant energy levels with respect to those of the neighboring organic layers. The factors affecting the operation of the intermediate connectors in tandem OLEDs, as demonstrated herein, provide guidance for the identification of new materials and device architectures for high-performance devices.

8kW LLC Isolated Converter Design for ESS Battery Charge/Discharge System (ESS 배터리 충방전 시스템을 위한 8kW급 LLC 절연형 컨버터 설계)

  • Kim, Jinwoo;Baek, Seunghoon;Cho, Younghoon;Koo, Tae-Geun
    • The Transactions of the Korean Institute of Power Electronics
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    • v.23 no.3
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    • pp.161-167
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    • 2018
  • In battery-operated systems, an isolated converter is used to interface the utility grid with the system to increase stability when charging and discharging batteries. Systems such as vehicle-to-grids (V2Gs), on-board chargers, and energy storage systems (ESSs) have recently become popular, and the roles of isolated converters have become important considerations in fabricating such devices. A fixed-frequency LLC converter, which is a type of isolated converter, presents the advantages of high efficiency and high power density by performing zero-voltage switching (ZVS) over wide frequency ranges. However, the magnetizing inductance of the LLC converter should be designed to enable ZVS in all switching devices. Therefore, in this study, the operating characteristics of the LLC circuit are analyzed, and an optimal design method for ZVS operation is established. Moreover, an 8 kW LLC high-efficiency and high-power-density resonant converter is designed and tested for ESS application. The LLC converter achieves 98% efficiency at rated power.