• Journal of information and communication convergence engineering
• /
• v.7 no.3
• /
• pp.361-365
• /
• 2009

This paper has been presented the transport characteristics of FinFET using the analytical potential model based on the Poisson's equation in subthreshold and threshold region. The threshold voltage is the most important factor of device design since threshold voltage decides ON/OFF of transistor. We have investigated the variations of threshold voltage and drain induced barrier lowing according to the variation of geometry such as the length, width and thickness of channel. The analytical potential model derived from the three dimensional Poisson's equation has been used since the channel electrostatics under threshold and subthreshold region is governed by the Poisson's equation. The appropriate boundary conditions for source/drain and gates has been also used to solve analytically the three dimensional Poisson's equation. Since the model is validated by comparing with the three dimensional numerical simulation, the subthreshold current is derived from this potential model. The threshold voltage is obtained from calculating the front gate bias when the drain current is $10^{-6}A$.

• Proceedings of the KIEE Conference
• /
• 2006.04a
• /
• pp.183-185
• /
• 2006

This paper presents a SISO nonlinear controller for the power system consisting of a synchronous generator connected to an infinite bus. The proposed controller is based on input-output feedback linearization, with a modified version of the terminal voltage equation used as the output. The resulting closed-loop has no internal dynamics, and thus stability is guaranteed. The controller performance is seen to be effective through simulations.

• Proceedings of the KIEE Conference
• /
• 1997.07c
• /
• pp.1118-1120
• /
• 1997

This paper presents a simple method for evaluating of voltage stability using the line flow equation. Line flow equations ($P_{ij}$, $Q_{ij}$) are comprised of state variable, $V_i$, ${\delta}_i$, $V_j$ and ${\delta}_j$, and line parameter, r and x. Using the feature of polar coordinate, these becomes one equation with two variables, $V_i$ and $V_j$. Moreover, if bus j is slack or generater bus, which is specified voltage magnitude, it becomes one equation with one variable $V_i$, that is, may be formulated with the second-order equation for $V_i^2$. Therefore, multiple load flow solutions may be obtained with simple computation, and the formulated equation used for approximately evaluating of voltage stability limit considering line flow sensitivity. The proposed method was validated to 2-bus and IEEE 6-bus system.

• Proceedings of the KIEE Conference
• /
• 1996.07b
• /
• pp.797-799
• /
• 1996

This paper presents a simple method for evaluating of voltage stability using the line flow equation. Line flow equations($P_{ij}$, $Q_{ij}$) are comprised of state variable, $V_i$, ${\delta}_i$, $V_j$ and ${\delta}_j$, and line parameter, r and x. Using the feature of polar coordinate, these equations become one equation with two variables, $V_i$ and $V_j$. Moreover, if bus j is slack bus or generator bus, which is specified voltage magnitude, it becomes One equation with one variable $V_i$, that is, may be formulated with the second-order equation for $V_i^2$. Therefore, solutions are obtained with simple computation. Solutions obtained are used for evaluating of voltage stability through sensitivity analysis. Also, considering of reactive power source, method for evaluating the voltage stability is introduced. The proposed method was validated to 2-bus and IEEE 6-bus system.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.6 no.1
• /
• pp.27-28
• /
• 1992

This paper derives the emphirical equation of high pressure mercury discharge lamp voltage. This equation consists of mercury weight per unit length and lamp diameter. The lamp input lies 80∼100 [W/cm].

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.49 no.1
• /
• pp.9-14
• /
• 2000

When current flows through a thick conductor such, most of the current flows along outside of the conductor, which is called skin effect. This paper represents a method calculating such a current distribution in the conductor region. The conductor region is divided into some pieces and each piece has its own unknown variable, i.e. current density. The governing equation which expresses Maxwell's equation is combined with the circuit equation with voltage source. The combined equation is solved to obtain current distribution in the conductor. This algorithm is applied to EMC(Electromagnetic Casting) to calculate current density with voltage source.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.65 no.8
• /
• pp.1355-1361
• /
• 2016

The inter-turn fault (ITF) causes the negative sequence components in the d -q voltage equation due to an increase in the unbalance of three-phase input currents. For this reason, d -q voltage equation become complicate as the voltage equation is classified into positive and negative components. In this study, we propose a simplified d -q equivalent circuit of an interior permanent magnet synchronous motor under ITF state. First, we proposed modeling method for d -q current based on the finite element method simulation results. Then, we developed the simplified d -q equivalent circuit by applying the proposed d -q current modeling.

• Journal of information and communication convergence engineering
• /
• v.8 no.1
• /
• pp.107-111
• /
• 2010

This paper has presented the dependence of the threshold voltage on back gate bias and drain voltage for FinFET. The FinFET has three gates such as the front gate, side and back gate. Threshold voltage is defined as the front gate bias when drain current is 1 micro ampere as the onset of the turn-on condition. In this paper threshold voltage is investigated into the analytical potential model derived from three dimensional Poisson's equation with the variation of the back gate bias and drain voltage. The threshold voltage of a transistor is one of the key parameters in the design of CMOS circuits. The threshold voltage, which described the degree of short channel effects, has been extensively investigated. As known from the down scaling rules, the threshold voltage has been presented in the case that drain voltage is the 1.0V above, which is set as the maximum supply voltage, and the drain induced barrier lowing(DIBL), drain bias dependent threshold voltage, is obtained using this model.

• Journal of Power Electronics
• /
• v.16 no.1
• /
• pp.1-8
• /
• 2016

Dead time is typically incorporated in voltage source inverter systems to prevent short circuit cases. However, dead time causes an error between the output voltage and reference voltage. Hence, voltage equation-based algorithms, such as motor parameter estimation and back electromotive force (EMF)-based sensorless algorithms, are prone to estimation errors. Several dead-time compensation methods have been developed to reduce output voltage errors. However, voltage errors are still common in zero current crossing areas, and an effect of the error is much worse in a low speed region. Therefore, employing voltage equation-based algorithms in low speed regions is difficult. This study analyzes the conventional dead-time compensation method and output voltage errors in low speed operation areas. A current shaping method that can reduce output voltage errors is also proposed. Experimental results prove that the proposed method reduces voltage errors and improves the accuracy of the parameter estimation method and the performance of the back EMF-based sensorless algorithm.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.29 no.7
• /
• pp.387-393
• /
• 2016

Threshold voltage shift has been observed from many thin-film transistors (TFTs) and the time evolution of the shift can be modeled as the stretched-exponential and -hyperbola function. These analytic models are derived from the kinetic equation for defect-creation or charge-trapping and the equation consists of only reversible reactions. In reality TFT's a shift is permanent due to an irreversible reaction and, as a result, it is reasonable to consider that both reversible and irreversible reactions exist in a TFT. In this paper the case when both reactions exist in parallel and make a combined threshold voltage shift is modeled and simulated. The results show that a combined threshold voltage shift observed from a TFT may agrees with the analytic models and, thus, the analytic models don't guarantee whether the cause of the shift is defection-creation or charge-trapping.