• Title/Summary/Keyword: Transfer stability

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Investigation of the effects of common and separate ground systems in wireless power transfer

  • Park, Woocheon;Moon, Jung-Ick;Cho, In-kui
    • ETRI Journal
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    • v.44 no.2
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    • pp.339-345
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    • 2022
  • This article presents an investigation of the effects on a grounding system of wireless power transfer (WPT) when transmitting over relatively far distances, that is, up to 1.25 m. Conventional two-coil WPT systems are sufficiently commercialized in strong coupling range, but it is important to accomplish the long-range WPT in weak coupling range for further various applications. This system depends on the coupling effect between the two coils that the grounds of the transmitting and receiving coils should be completely separated. However, when evaluating the performance of two-coil systems with the instrument consisting of two ports and one common ground, undesirable problems occur in weak coupling ranges, for example, obtaining disagreeable transmission efficiency and degrading system stability/reliability. We investigate the problems of the leakage power from common ground systems and provide a practical solution to obtain a reliable WPT system by using an isolation transformer. The usefulness of this approach is that it is possible to achieve the stability of the system with relatively far transmitting distances and to determine the exact transmission efficiency.

Stability Analysis of Feed-forward Type VSVI Active EMI filter (전압센싱 전압주입 전향 능동형 EMI 필터의 안정도해석)

  • Kang, Byeong-Geuk;Choi, Yong-Oh;Chung, Se-Kyo
    • Proceedings of the KIPE Conference
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    • 2016.07a
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    • pp.329-330
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    • 2016
  • This paper deals with stability of active EMI filter. Feed-forward type voltage-sensing voltage-injection (VSVI) AEF is best topology when considering the filter size and leakage current. But it is not studied in stability. Therefore, the detailed and simplified transfer function is derived and it is used to analyze stability. The experimental results are provided to verify the effectiveness of the analysis.

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Analysis of Quenching Resistor Effect to Improve Stability of TIA Circuit for APD (APD용 TIA 회로의 안정성 개선을 위한 Quenching 저항 영향 분석)

  • Ki, Dong-Han;Jin, Yu-Rin;Kim, Sung-Mi;Cho, Seong-Ik
    • Journal of IKEEE
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    • v.26 no.3
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    • pp.373-379
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    • 2022
  • In this paper, since the APD(Avalanche Photo Diode) for LTV(Light to Voltage) conversion uses a high voltage in the operating range unlike other PD(Photo Diode)s, the quenching resistor must be connected in series to prevent overcurrent when using the TIA(Transimpedance Amplifier). In such a case, quenching resistance may affect the transfer function of the TIA circuit, resulting in serious stability. Therefore, in this paper, by analyzing the effect of APD quenching resistance on the voltage and current loop transfer function of TIA, we propose a loop analysis and a method for determining the quenching resistance value to improve stability. TIA circuit with quenching resistance was designed by the proposed method and the stability of operation was verified through simulation and chip fabrication.

Stability analysis of gas-liquid interface using viscous potential flow (점성포텐셜유동을 이용한 이상유동장의 표면안정성 해석)

  • Kim, Hyung-Jun;Kwon, Se-Jin
    • Proceedings of the KSME Conference
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    • 2007.05b
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    • pp.3033-3038
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    • 2007
  • In this research, Rayleigh instability of gas-liquid flow in annular pipe is studied in film boiling using viscous potential flow. Viscous potential flow is a kind of approximation of gas-liquid interface considering velocity field as potential including viscosity. A dispersion relation is obtained including the effect of heat and mass transfer and viscosity. New expression for dispersion relation in film boiling and critical wave number is obtained. Viscosity and heat and mass transfer have a stabilizing effect on instability and its effect appears in maximum growth rate and critical wave number. And the existence of marginal stability region is shown.

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Vortex Instability and Heat Transfer Correlations in the Natural Convection Flow over Inclined Isothermal flat Plates (경사진 등온 평판위 의 자연대류 유동 에서의 와류 불안정성 과 열전달 상관관계)

  • 최창균;유정열;이형인
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.8 no.1
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    • pp.10-17
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    • 1984
  • The critical conditions marking the onset of thermally induced vortices over an inclined iso-thermal plate are investigated using the linear stability theory. The stability equations are simplified by estimating the orders of magnitude of respective terms. The analysis is carried out under the assumption that for the system of large Prandtl numbers temperature disturbances are initiated within the conventional thermal boundary layer of the basic flow. The stability criteria obtained from the present results agree well with those of the existing quasi-parallel flow models. In addition it is found that the critical conditions generate the heat transfer correlation in good agreement with experiments. Therefore, it is suggested that the validity of existing theoretical models will be reexamined.

Stability Analysis of Nonlinear Pulse-Modulated System Subject to Gaussian Noise (가우스 잡음을 고려한 비선형 펄스 변조 시스템의 안정도 분석)

  • 강영채
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.19 no.6
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    • pp.67-79
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    • 1982
  • The stability of general pulse-width modulation system with Gaussian random disturbance was discussed . General system is divided into nonlinear and linear elements using the conventional describing function method. The concept of the equivalent admittance was used to find the transfer characteristic of the nonlinear element of the system. In this paper the self-sustained oscillation condition in the autonomous system was derived and the results was analyzed with computer simulation.

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The Site Selection of 100MVA STATCOM for Voltage Stability Enhancement in Korean Metropolitan Area (수도권 전압안정도 향상을 위한 100MVA STATCOM 위치선정 연구)

  • Chang, Byung-Hoon;Kim, Soo-Yul;Han, Jeong-Yeol;Choi, Don-Keun;Song, Hwa-Chang;Lee, Byong-Joon
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.56 no.9
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    • pp.1543-1548
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    • 2007
  • This paper reports a study on determination of the adequate location of 100 MVA STATCOM regarding the transfer capability enhancement on the metropolitan interface as well as the economy in system operation. The base case in the study was established considering a scenario of the energy support to North Korea from the KEPCO (Korea Electric Power Corporation) system through a HVDC interconnection. In the base case, the energy support was approximately modeled with a load of 1500 MW, and by the load addition, the system was weakened in terms of voltage stability and transfer capability. After a thorough investigation on the case, the location of the STATCOM was decided to compensate the reactive deficit of the modified system and to maximize the operational benefit which can be estimated by FV analysis.

The Roles of Aramid Pulp and Potassium Titanate Whisker in the Automotive Friction Materials (자동차용 마찰재에 사용되는 아라미드 섬유와 티탄산칼륨 섬유의 역할)

  • Kim, Seong-Jin;Lim, Hyun-Woo;Jang, Ho
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 1999.11a
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    • pp.213-218
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    • 1999
  • Friction and wear characteristics of novolac resin-based friction materials reinforced with aramid pulp and potassium titanate were investigated by using a pad-on-disk type friction tester. Friction properties such as friction stability, surface morphology, and wear rate varied according to the relative amount of aramid pulp and potassium titanate. The friction materials reinforced with both aramid pulp and potassium titanate showed superior friction stability and wear resistance due to the formation of durable transfer layer.

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Hole Transfer Layer p-doped with a Metal Oxide for Low Voltage Operation of OLEDs

  • Shin, Won-Ju;Lee, Je-Yun;Kim, Jae-Chang;Yoon, Tae-Hoon;Kim, Tae-Shick;Song, Ok-Keun
    • 한국정보디스플레이학회:학술대회논문집
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    • 2007.08a
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    • pp.435-438
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    • 2007
  • $V_{2}O_{5}$ was tested as a p-dopant for lower operating voltage and higher stability of OLEDs. Low voltage and high stability were achieved using this doping layer. It can be separated to bulk and interface contributions and the latter is a more dominant factor both of operation voltage and stability.

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Evaporator Superheat Control of a Multi-type Air-conditioning/Refrigeration System (멀티형 공조/냉동시스템의 증발기 과열도 제어)

  • Kim, Tae-Sub;Hong, Keum-Shik;Sohn, Hyun-Chul
    • Proceedings of the KSME Conference
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    • 2001.06b
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    • pp.712-717
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    • 2001
  • This paper investigates the control problem of evaporator superheat, i.e., the difference between the temperature of the refrigerant at the entrance region of an evaporator and that at the exit region, for multi-type air-conditioning/refrigeration systems. Mathematical equations describing the characteristics of compressor, condenser, evaporator, and electronic expansion valve are first derived. Then, the transfer functions from the current input of the electronic expansion valve to wall temperatures of evaporator tube at two-phase region and superheated region, respectively, are derived. The stability and performance of the closed loop system with a PI controller are analyzed by Nyquist stability criterion. Simulation results are provided.

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