• Journal of the Korean Institute of Telematics and Electronics A
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• 제31A권1호
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• pp.54-60
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• 1994

In this paper, we present the analytical models for the change of the lateral electric field distribution and the velocity saturation region length with the electron trapping of stressed SC-PMOSFET in the saturation region. To derive the hot-electron-induced lateral electric field of stressed SC-PMOSFET. Ko's pseudo two dimensional box model in the saturation region which illustrates the analysis of the velocity saturation region is modified under the condition of electron trapping in the oxide near the drain region. From the results, we have the following lateral electric field in the y-direction, that is, E(y) ES1satT.cosh(y/l) qNS1tT.sinh(y/l)/lCox. It is shown that the trapped electrons influence the field in the drain region. decreasing the lateral electric field. Calculated velocity saturaion length increases with the trapped electrons. increasing the drain current of stressed SCPMOSFET. This results well explain the HEIP phenomenon of PMOSFET's.

• Proceedings of the KIPE Conference
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• 전력전자학회 2006년도 전력전자학술대회 논문집
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• pp.428-431
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• 2006

Matching transformer in Dynamic Voltage Compensator is needed for grid connection and isolation. Flux saturation in transformer will be occurred by voltage of transformer from inverter and DC offset voltage and flux saturation makes over current in transformer. In this paper, mathematical modeling of matching transformer is proposed for flux saturation simulation of Dynamic Voltage Compensator.

• Journal of Power Electronics
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• 제9권2호
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• pp.188-197
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• 2009

This paper presents an adaptive flux observer to estimate stator flux linkage and stator inductances of an interior permanent-magnet synchronous machine considering magnetic saturation. The concept of static and dynamic inductances due to saturation is introduced in the machine model to describe the relationship between current and flux linkage and the relationship between their time derivatives. A flux observer designed in the stationary reference frame with constant inductance is analyzed in the rotor reference frame by a frequency-response characteristic. An adaptive algorithm for an on-line inductance estimation is proposed and a Lyapunov-based analysis is given to discuss its stability. The dynamic inductances are estimated by using Taylor approximation based on the static inductances estimated by the adaptive method. The simulation and experimental results show the feasibility and performance of the proposed technique.

• Journal of Communications and Networks
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• 제12권1호
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• pp.43-51
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• 2010

IEEE 802.11 defines distributed coordination function (DCF), which is characterized by CSMA/CA and binary exponential backoff (BEB) algorithm. Most modifications on DCF so far have focused on updating of the contention window (CW) size depending on the outcome of own frame transmission without considering freezing periods experienced in the backoff interval. We propose two simple but novel schemes which effectively utilize the number of freezing periods sensed during the current backoff interval. The proposed schemes can be applied to DCF and its family, such as double increment double decrement (DIDD). Saturation throughput of the proposed schemes is analyzed by means of Bianchi's Markovian model. Computer simulation validates the accuracy of the analysis. Numerical results based on IEEE 802.11b show that up to about 20% improvement of saturation throughput can be achieved by combining the proposed scheme with conventional schemes when applied to the basic access procedure.

• Korean Journal of Optics and Photonics
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• 제2권2호
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• pp.67-73
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• 1991

The unsaturated signal gain, signal gain bandwidth, and saturation power which are important parameters determining characteristics of the semiconductor laser amplifier were measured for an AlGaAs Fabry-Perot cavity type laser amplifier and compared with the results of Fabry-Perot formula. The unsaturated signal gain 25 dB is obtained near oscillation thereshold current at $0.7\mu\textrmW$ input power. The corresponding signal gain bandwidth was about 3 GHz. Also. We measured the variation of the saturation signal gain and saturation power.

• Proceedings of the IEEK Conference
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• 대한전자공학회 1998년도 추계종합학술대회 논문집
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• pp.541-544
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• 1998

A SiGe p-channel MESFET using $\delta-doped$ layers is designed and the considerable enhancement of the current driving capability of the device is observed from the result of simulation. The channel consists of double $\delta-doped$ layers separated by a low-doped spacer which consists of Si and SiGe. A quantum well is formed in the valence band of the Si/SiGe heterojunction and much more holes are accumulated in the SiGe spacer than those in the Si spacer. The saturation current is enhanced by the contribution of the holes inthe spacer. Among the design parameters that affect the performance of the device, the thickness of the SiGe layer and the Ge composition are studied. The thickness of $0~300\AA$ and the Ge composition of 0~30% are investigated, and the saturation current is observed to be increased by 45% compared with a double $\delta-doped$ Si p-channel MESFET.

• Proceedings of the KIEE Conference
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• 대한전기학회 2005년도 추계학술대회 논문집 전력기술부문
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• pp.49-51
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• 2005

The saturation of transformer for short-circuit test suppress the peak current value during the test. And such phenomenon effect on the test results occasionally. This paper deals with the induction of the formula to restore the peak current value from the measured data.

• Journal of the Korean Institute of Telematics and Electronics D
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• 제34D권12호
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• pp.69-75
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• 1997

A Si-channle MESFET using .delta.-doped layers was designed and the considerable enhancement of the current driving capability of the device was observed by simulation. The channel consists of double .delta.-doped layers separated by a low-doped spacer. Cariers are spilt from the .delta.-doped layers and are accumulated in the spacer. The saturation current is enhanced by the contribution of the carriers in the spacer. Among the design parameters that affect the peformance of the device, the thickness of the spacer and the ratio of the doping concentrations of the two .delta.-doped layers were studied. The spacer thickenss of 300~500.angs. and the doping ratio of 3~4 were shown to be the optimized values. The saturation current was observed to be increased by 75% compared with a bulk-channel MESFET. The performances of transconductance, output resistance, and subthreshold swing were also enhanced.

• The Transactions of the Korean Institute of Electrical Engineers C
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• 제53권7호
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• pp.358-363
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• 2004

A new 600 V dual gate transistor employing thyristor action, which incorporates floating PN junction and trench gate IGBT, is proposed to improve the forward current-voltage characteristics and the short circuit ruggedness. Our two-dimensional numerical simulation shows that the proposed device exhibits low forward voltage drop and eliminates the snapback phenomena compared with conventional trench gate IGBT and EST The proposed device achieves high current saturation characteristics by separating floating N+ emitter and cathode. The proposed device achieves low saturation current value compared with conventional devices, and the short-circuit ruggedness is improved. The proposed device may be suitable for the use of high voltage switching applications.

• Proceedings of the KSR Conference
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• 한국철도학회 1999년도 추계학술대회 논문집
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• pp.360-367
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• 1999

An inverter-driven induction motor is used as the traction motor for a high speed drive system that required safety, reliabillity, performance, compact size owing to the space and weight alloted for attaching to train, etc. particularly it is possible to happen the saturation effects of flux density at constant voltage-frequency region and then increase very higher than the at lowed capacity of no-load current and temperature in any case. therefore the optimum design of core, optimum voltage-frequency ratio, adoption of high grade magnetic core have been developed and researched for preventing these problems. this paper show the saturation effects of traction rotor by measuring the induced voltage of search coil at stator teeth and presents optimum voltage-frequency ratio as well as optimum core design through the comparison with efficiency, power factor, load current and no-load current for korea high speed train.