• Environmental Engineering Research
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• 제11권3호
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• pp.164-171
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• 2006

Numerical modeling of the flow velocity fields for the near corona wire electrohydrodynamic (EHD) flow was conducted. The steady, two-dimensional momentum equations have been computed for a wire-plate type electrostatic precipitator (ESP). The equations were solved in the conservative finite-difference form on a fine uniform rectilinear grid of sufficient resolution to accurately capture the momentum boundary layers. The numerical procedure for the differential equations was used by SIMPLEST algorithm. The Phoenics (Version 3.5.1) CFD code, coupled with Poisson's electric field, ion transport equations and the momentum equation with electric body force were used for the numerical simulation and the Chen-Kim ${\kappa}-{\varepsilon}$ turbulent model numerical results that an EHD secondary flow was clearly visible in the downstream regions of the corona wire despite the low Reynolds number for the electrode ($Re_{cw}=12.4$). Secondary flow vortices caused by the EHD increases with increasing discharge current or EHD number, hence pressure drop of ESP increases.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 춘계학술대회 논문집
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• pp.103-106
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• 1999

In this paper, we suggest the FED packaging technology that have 4mm thickness, using sodalime glass-to-sodalime glass electrostatic bonding. It based on conventional silicon-glass bonding. The silicon film was deposited an around the exhausting hole on FED backside panel. And then, the silicon film of panel was successfully bonded with capping(bare) glass in vacuum environment and the FED panel was vacuum-sealed. In this method, we could achieve more 153 times increased conductance and 200 times increased vacuum efficiency than conventional tube packaging method. The vacuum level in panel, by SRG test, was maintained about low 10$_{-4}$ Torr during above two months And, the light emission was observed to 0.7-inch tubeless packaged FED. Then anode current was 34 $\mu$ A. Emission stability was constantly measured for 10 days.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 추계학술대회 논문집 전기물성,응용부문
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• pp.97-98
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• 2006

High current behaviors of extended drain n-type metal-oxide-semiconductor field effects transistor (EDNMOS) with double polarity source (DPS) for electrostatic discharge (ESD) protection are analyzed. Simulation based contour analyses reveal that combination of bipolar junction transistor operation and deep electron channeling induced by high electron injection gives rise to the second on-state. Therefore, the deep electron channel formation needs to be prevented in order to realize stable and robust ESD protection performance. Based on our analyses, general methodology to avoid the double snapback and to realize stable ESD protection is to be discussed.

• Structural Engineering and Mechanics
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• 제76권5호
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• pp.619-629
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• 2020

In current study, surface/interface effects for pull-in voltage and viscous fluid velocity effects on dimensionless natural frequency (DNF) of fluid-conveying piezoelectric nanosensor (FCPENS) subjected to direct electrostatic voltage DC with nonlinear excitation, harmonic force and also viscoelastic foundation (visco-pasternak medium and structural damping) are investigated using Gurtin-Murdoch surface/interface (GMSIT) theory. For this analysis, Hamilton's principles, the assumed mode method combined with Lagrange-Euler's are used for the governing equations and boundary conditions. The effects of surface/interface parameters of FCPENS such as Lame's constants (λI,S, μI,S), residual stress (τ0I,S), piezoelectric constants (e31psk,e32psk) and mass density (ρI,S) are considered for analysis of dimensionless natural frequency respect to viscous fluid velocity u̅f and pull-in voltage V̅DC.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.63-66
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• 2000

In this paper, we present the simulation of the heterojunction bipolar transistor with different Emitter-Base junction structures. Our simulation results include effect of setback and graded layer. We prove the emitter efficiency's improvement through setback and graded layer. In 1995, the analytical equations of electric field, electrostatic potential, and junction capacitance for abrupt and linearly graded heterojunctions with or without a setback layer was derived. But setback layer and linearly graded layer's recombination current was considered numerically. Later, recombination current model included setback layer and graded layer will be proposed. New recombination current model also wile include abrupt heterojunction's recombination current model. In this paper, the material parameters of the heterojunction bipolar transistor with different Emitter-Base junction structures is introduced.

• 한국전기전자재료학회논문지
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• 제23권9호
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• pp.724-729
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• 2010

We have proposed a new configuration on the cathode structure to improve a neutron yield without the application of external ion sources in an inertial electrostatic confinement (IEC) device. A neutron yield in the IEC device is closely related to the potential well structure generated inside the cathode and is proportional to the ion current. Therefore, the application of a double grid cathode structure to the IEC device is expected to produce a higher ion current and neutron yield than at a single grid cathode due to a high electric field strength generated around the cathode. These possibilities were verified as compared with the ion current calculated from both shape of the single and double grid cathode. Additionally from the results of ion's lives and trajectories examined at various outer cathode voltages and grid cathode configurations by using particle simulations, the validity of the double grid cathode was confirmed.

• 전기학회논문지
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• 제56권3호
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• pp.465-471
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• 2007

The one step type pole and two step type pole are used in KEPCO's distribution system. The neutral current increases in three-phase four-wire distribution system due to unbalanced load. Usually, power line and communication line are installed at contiguity by effect of topography in Korea. To this end, the damages such as electrostatic induction, electromagnetic induction and harmonic induction generated by induced voltage and current are occured in power line and communication line. This paper calculates the neutral current in KEPCO's distribution system using EMTP by composing various simulated conditions. Also, these results are verified by vector analysis.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1990년도 추계학술대회 논문집 학회본부
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• pp.176-179
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• 1990

In this paper, the pheonmena of flowing electrification is experimently studied in the model transformer of a super high voltage transformer. The current of natural terminal which is flowed by the flowing electrification is increased according to oil flow, but according to the oil temperature the current is decreased and the direction of the current is changed.

• ETRI Journal
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• 제31권6호
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• pp.725-731
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• 2009

In this paper, electrostatic discharge (ESD) protection circuits with an advanced substrate-triggered NMOS and a gate-substrate-triggered NMOS are proposed to provide low trigger voltage, low leakage current, and fast turn-on speed. The proposed ESD protection devices are designed using 0.13 ${\mu}m$ CMOS technology. The experimental results show that the proposed substrate-triggered NMOS using a bipolar transistor has a low trigger voltage of 5.98 V and a fast turn-on time of 37 ns. The proposed gate-substrate-triggered NMOS has a lower trigger voltage of 5.35 V and low leakage current of 80 pA.

• 한국안전학회지
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• 제11권3호
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• pp.89-96
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• 1996

This paper presents a study on the analysis and evaluation for ELF( Extremely Low Frequency) electric and magnetic fields under the transmission line according to the power system states. The power system states are classified into two types, normal state resulting from normal operation and alert state from outages. The current in a system is changed continually owing to the load fluctuations even in a normal operation. To calculate the current of the concerned line in a normal state, the system load level is devided into light, base and heavy load level. In case of contingency, an efficient algorithm based on matrix inversion lemma is developed to figure out the current changes. In order to analyze the variations of ELF field caused by the current fluctuations the electrostatic field approach which is far simpler than the electromagnetic field one based on Maxwell equation is introduced in this paper. The suggested method is applied to the IEEE 14 bus system to demonstrate the usefulness.