• Title/Summary/Keyword: Drop time

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Multiple-Output Low Drop-Out Regulator With Constant Feedback Factor (고정 피드백 인자를 사용하는 다중출력 LDO 레귤레이터)

  • Mo, Hyunsun;Kim, Daejeong
    • Journal of IKEEE
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    • v.22 no.2
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    • pp.384-392
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    • 2018
  • A multiple-output LDO regulator is a good choice in terms of the efficiency in embedded systems requiring various supply voltages. A small feedback factor in LDO incurs the long settling time, resulting in large ripples in the time-multiplexing strategy. A new proposed topology enhances the settling time, and hence the ripples by incorporating the constant feedback factor with different reference voltages. The simulation results of a prototype design in a standard $0.35{\mu}m$ CMOS process verify that the proposed strategy enhances the settling time and ripple characteristic by more than doubled than a conventional circuit using the feedback factor of less than 0.4.

Quantitative estimation of reversibility of the discharge process undergone by nickel hydroxide film cathodically deposited on pure nickel as a positive supercapacitor electrode using cyclic voltammetry and potential drop method

  • Pyun Su-Il;Moon Sung-Mo
    • Journal of the Korean Electrochemical Society
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    • v.1 no.1
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    • pp.8-13
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    • 1998
  • This work presents the way how to evaluate the degree of reversibility of the discharging process undergone by the nickel hydroxide film cathodically deposited on pure nickel as a positive electrode for electrochemical capacitor using the combined cyclic voltammetry and potential drop method, supplemented by galvanostatic discharge and open-circuit potential transient methods. The time interval necessary just to establish the current reversal of anodic to cathodic direction from the moment just after applying the potential inversion of anodic to cathodic direction, was obtained on cyclic voltammogram. The cathodic charge density passed upon dropping the applied potential, was calculated on potentiostatic current density-time curve. Both the time interval and the cathodic charge density in magnitude can be regarded as being measures of the degree of reversibility of the discharging process undergone by the positive active material for supercapacitor, i.e. , the longer the time interval is, the lower is the degree of reversibility and the greater the cathodic charge density is, the higher is the degree of reversibility. From the applied potential dependences of the time interval and cathodic charge density, discharge at $0.42 V_{SCE}$ was determined to be the most reversible.

Dynamic Transient Phenomena of Proton Exchange Membrane Fuel Cell

  • Lee, Ying;Choi, Yong-Sung;Zhang, You-Sai;Lee, Kyung-Sup
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2010.03b
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    • pp.9-9
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    • 2010
  • The proton exchange membrane fuel cell (PEMFC) holds great promise of clean power. However, in practical applications which use the PEMFC as the power source, the output voltage from the fuel cell undergoes transient response especially during acceleration and deceleration. This paper presents the relationships between the internal voltage drop, voltage of time constant, time constant of FC1 and FC2 (in series and in parallel) charge curves and discharge curves respectively.

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A Study on Verification of PowerRail based on Voltage Drop under Extended Feeding Condition (연장급전 전압강하 계산을 위한 전기철도 급전 시뮬레이터의 검증에 관한 연구)

  • Kim, Joorak
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.64 no.2
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    • pp.331-337
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    • 2015
  • The power flow analysis of electrified railway is required complicated calculation, because of variable load. Train runs trough rail supplied by electric power therefore, the load value in electrified railway system fluctuates along time. The power flow algorithm in electrified railway system is different from general power system, and the power flow simulation is peformed by the particular simulation software. Powerail is simulation software for analysis of traction power supply system developed by KRRI, in 2008. This consists of load forecasting module, including TPS and time scheduling, and power flow module. This software was verified by measured current under normal feeding condition, however, has not been verified by voltage on the condition of extended feeding. This paper presents the verification of PowerRail based on voltage drop under extended feeding condition. This is performed by comparing simulation result with field test. Field test and simulation is done in commercial railway line.

A Study fur Wettability of Silicate Glasses on Silicon Nitride (질화규소와 실리케이트계 유리의 젖음성에 관한 연구)

  • 안병국
    • Journal of Welding and Joining
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    • v.20 no.3
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    • pp.116-121
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    • 2002
  • For the accumulation of a fundamental knowledge about the behavior of glass solder during the joining of ceramics, the wettability of solder on silicon nitride have been measured by sessile drop method. $SiO_2-MgO-Al_2O_3$ g1ass solder and oxynitride glass solders were selected as examples while silicon nitride which were used as substrates. Contact angle of solder on silicon nitride didn't decrease with time at high nitrogen content in the solder, but low nitrogen content in solders have the time-dependent property. Reason which contact angle of low nitrogen content in solders decrease on silicon nitride was that diffusion of nitrogen take place between solder and silicon nitride.

The Effect of NIC Buffer Size of Web Server on the Performance of LAN (웹 서버의 NIC 버퍼 사이즈가 LAN 성능에 미치는 영향)

  • Kim, Jin-Hee;Sin, Bum-Suk;Kwon, Kyung-Hee
    • Journal of IKEEE
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    • v.7 no.2 s.13
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    • pp.260-264
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    • 2003
  • Among many factors to affect the network performance, this paper analyses how the buffer size of NIC(Network Interface Card) can affect web server and LAN(Local Area Network). We use the ns-2 which is defacto network simulation tool to observe the changes in drop rate, throughput, RTT(Round Trip Time), effective throughput depending on varying buffer sizes. And we analyse the effect of NIC buffer size on the web traffic in Ethernet.

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Study on changes in electrical and switching characteristics of NPT-IGBT devices by fast neutron irradiation

  • Hani Baek;Byung Gun Park;Chaeho Shin;Gwang Min Sun
    • Nuclear Engineering and Technology
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    • v.55 no.9
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    • pp.3334-3341
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    • 2023
  • We studied the irradiation effects of fast neutron generated by a 30 MeV cyclotron on the electrical and switching characteristics of NPT-IGBT devices. Fast neutron fluence ranges from 2.7 × 109 to 1.82 × 1013 n/cm2. Electrical characteristics of the IGBT device such as I-V, forward voltage drop and additionally switching characteristics of turn-on and -off were measured. As the neutron fluence increased, the device's threshold voltage decreased, the forward voltage drop increased significantly, and the turn-on and turn-off time became faster. In particular, the delay time of turn-on switching was improved by about 35% to a maximum of about 39.68 ns, and that of turn-off switching was also reduced by about 40%-84.89 ns, showing a faster switching.

Solubilization Mechanism of Hydrocarbon Oils by Polymeric Nonionic Surfactant Solution (고분자 비이온 계면활성제 수용액에 의한 탄화수소 오일의 가용화 메커니즘)

  • Bae, Min Jung;Lim, Jong Choo
    • Korean Chemical Engineering Research
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    • v.47 no.1
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    • pp.24-30
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    • 2009
  • In this study, solubilization experiments of n-decane, n-undecane and n-dodecane oil were performed by micellar solutions of polymeric nonionic surfactant Pluronic L64($EO_{13}PO_{30}EO_{13}$) at room temperature. A single spherical drop of hydrocarbon oil was injected into aqueous surfactant solution using an oil drop contacting technique and solubilization rate of hydrocarbon oil was measured by observing the size of oil drop with time. It was shown that solubilization rate decreased with the alkane carbon number(ACN) of the hydrocarbon oil. The solubilization rate was also found to be independent of initial oil dorp size and almost linearly proportional to the initial surfactant concentration. These results revealed that solubilization of n-decane, n-undecane and n-dodecane oils by L64 micellar solution is controlled by interface-controlled mechanism but not by diffusion-controlled mechanism. The equilibrium solubilization capacity(ESC) was measured by a turbidimeter and the result showed that EAC decreased with an increase in ACN but increased with both increases in surfactant concentration and solubilization rate. Dynamic interfacial tension measurements showed that interfacial tension and equilibrium time increased with an increase in ACN of hydrocarbon oil but decreased with an increase in surfactant concentration.

Chaoticity Evaluation of Ultrasonic Signals in Welding Defects by 6dB Drop Method (6dB Drop법에 의한 용접 결함 초음파 신호의 카오스성 평가)

  • Yi, Won;Yun, In-Sik
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.23 no.7 s.166
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    • pp.1065-1074
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    • 1999
  • This study proposes the analysis and evaluation method of time series ultrasonic signal using the chaotic feature extraction for ultrasonic pattern recognition. Features extracted from time series data using the chaotic time series signal analysis quantitatively welding defects. For this purpose analysis objective in this study is fractal dimension and Lyapunov exponent. Trajectory changes in the strange attractor indicated that even same type of defects carried substantial difference in chaoticity resulting from distance shills such as 0.5 and 1.0 skip distance. Such differences in chaoticity enables the evaluation of unique features of defects in the weld zone. In experiment fractal(correlation) dimension and Lyapunov exponent extracted from 6dB ultrasonic defect signals of weld zone showed chaoticity. In quantitative chaotic feature extraction, feature values(mean values) of 4.2690 and 0.0907 in the case of porosity and 4.2432 and 0.0888 in the case of incomplete penetration were proposed on the basis of fractal dimension and Lyapunov exponent. Proposed chaotic feature extraction in this study enhances ultrasonic pattern recognition results from defect signals of weld zone such as vertical hole.

A Novel Dead Time Minimization Algorithm for improving the inverter output waveforms (인버터 출력파형 개선을 위한 새로운 휴지기간 최소화 알고리즘)

  • Han, Yun-Seok;Choe, Jeong-Su;Kim, Yeong-Seok
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.48 no.5
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    • pp.269-277
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    • 1999
  • In this paper, a novel dead time minimization algorithm is proposed for improving the output waveform of an inverter. The adverse effects of the dead time are mainly described by the voltage drop and the distortion factor of waveforms. The principle of the proposed algorithm is organized with forbidding unnecessary firings fo the inverter switches which are not conducted even though the gate signal is impressed. The proposed methods are explained with the conduction mode of output currents. The H/W and S/W implementation method of the proposed algorithm are also presented. The validity of the proposed algorithm is verified by comparing the simulation and experimental results with conventional methods. It can be concluded from the results that the proposed algorithm has the advantage which is able to reduce the harmonics in the output voltages and which the output voltage can nearly be equal to the reference value. Another advantage of the proposed method is the reduction of total numbers of switching so that the switching losses of inverter drives can be minimized.

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