• Journal of Astronomy and Space Sciences
• /
• v.11 no.2
• /
• pp.250-272
• /
• 1994

Various plasma instabilities driven by the ion beams have been proposed in order to explain the broadband electrostatic noise (BEN) in the earth's geomagnetic tail. Ion acoustic, ion-ion two stream, and electron acoustic instabilities have been proposed. Here we consider a theoretical investigation of the generation of BEN by cold streaming ion beams in the earth's magnetotail. Linear theory analysis and particle simulation studies for the plasma sheet, which consists of warm electrons and ions as well as cold streaming ion beams, have been done. Both beam-ion acoustic and ion-ion two stream instabilities easily occur when the beam and warm electron temperature ratio, $T_b/T_e$ is small enough. The numerical simulation results confirm the existence of broadband electrostatic noise whose frequency is ranged from $\omega$=0 to $\omega$$\omega_{pe}$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.17 no.4
• /
• pp.448-452
• /
• 2004

The micromachined variable optical attenuator(VOA) was presented in the paper. The VOA has two single mode fiber(SMF) aligned with free space and symmetric parallel plate actuator with microshutter, which can control a amount of light by driving the actuator. In the paper, analysis on driving performances of the VOA was performed and can be reduced threshold voltage through the decreasing displacement actuating range. This paper presents a VOA that is fabricated using bosch deep silicon etching process with silicon on insulator(SOD wafer. The VOA consists of driving electrode, ground electrode, actuating microshutter, and mechanical stopper. In this VOA, actuating shutter is driven by electrostatic force and the threshold voltage is close to 28V, 46V come along with the spring width of 5${\mu}{\textrm}{m}$, 7${\mu}{\textrm}{m}$ respectively. Attenuation range is measured from 2.4㏈ to 16.7㏈.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.13 no.12
• /
• pp.1205-1213
• /
• 2001

The electrical characteristics and particle collection efficiency of a wide-plate spacing electrostatic precipitator are numerically investigated, and the results are compared with those obtained experimentally. The electric potential and field strength near the collection plate increase with increasing the plate spacing. The electric field strength of a discharge electrode of a twisted pin type is larger than that of a rectangular type. As the roughness factor of the discharge electrode wire becomes small, or the plate spacing becomes narrow, the corona current of the precipitator increases. The numerical results agree well with those obtained from experimental method.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.63 no.10
• /
• pp.1417-1422
• /
• 2014

Using a parallel plate DC plasma system was prepared. Using this equipment, we investigated the basic discharge characteristics of DC argon plasma in terms of electron density, temperature, voltage and current waveforms and plasma potential. The effects of the electrode gap distance, input voltage, ballast resistance and pressure were measured using electrostatic probe. Plasma simulation using fluid approximation has been performed. External circuit effects was included in the simulation. Measured and calculated current voltage characteristics show similar tendencies.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2004.11a
• /
• pp.656-661
• /
• 2004

Static and dynamic responses of micro double cantilever beam structures interacted by electrostatic forces are obtained employing Galerkin's method based on Euler beam theory. Variations of static and dynamic responses as well as natural frequencies are estimated for several sets of beam properties and applied voltages. It is shown that the variations of beam properties resulted by manufacturing process influence the deflections and the modal characteristics significantly. Such information can be usefully employed for the design of MEMS structures.

• Journal of the Semiconductor & Display Technology
• /
• v.22 no.3
• /
• pp.52-61
• /
• 2023

We designed a novel ultra-miniaturized microcolumn structure having an stigmator to significantly improve throughput per unit time, which is the biggest disadvantage of microcolumns. We adopted the structure of the stigmator in the form of an electrostatic octupole electrode, and used an electrostatic quadrupole deflector with a relatively simple structure considering the increase in wiring due to the introduction of the stigmator. We have dramatically reduced the effect of astigmatism that occurs when the electron beam probe is scanned to the periphery of the target by introducing the stigmator between the control electrode and the deflector. As our numerical analysis simulation results, the field of view obtained as a result of this study is about 46.3% improved compared to our previous study, and the electron beam probe size of less than 10 nm was achieved in the entire field of view.

• Proceedings of the IEEK Conference
• /
• 2008.06a
• /
• pp.24-25
• /
• 2008

An Electrostatic discharge (ESD) protection has been a very important reliability issue in microelectronics, especially for RF (Radio Frequency) integrated circuits (ICs). This paper reviews design and analysis of on-chip ESD (electrostatic discharge) protection circuits for RF applications. Key issues in RF ESD protection, design methods, and RF ESD protection solutions are discussed.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.34D no.12
• /
• pp.1-7
• /
• 1997

Serious troubles may occur in electromagnetic equipments due to electrostatic discharge (ESD). The number of the damaging incidents are significantly increasing with the increased use of integrated semiconductor elements with loer operation pwoer. In order to examine the phenomena theoretically, this paper anlyzes properties of the transient electromagnetic fields rdiated by ESD. A new model is presented using the Rompe-weizel formula for the spark resistance. The numerical results of ESD fields are compared with the experimental data that were given by wilson-Ma.

• Proceedings of the KIEE Conference
• /
• 2002.07c
• /
• pp.1982-1984
• /
• 2002

The admittance of one-port electrostatic actuator are modeled using the steady-state sinusoidal response. Also the admittance of the differential type actuator is derived taking the practical conditions into consideration, although it has no admittance in ideal case. It is a function of biasing error, driving error, and capacitive mismatch including parasitic capacitors. The validity of the admittance model is proved by comparing between the modeled and measured admittances. The distortion in the frequency response curve measured by a capacitive sensor is analyzed and it is concluded that the admittance is the main cause of this distortion.

• International Journal of Precision Engineering and Manufacturing
• /
• v.3 no.1
• /
• pp.43-48
• /
• 2002

This paper describes an automated computer-aided engineering (CAE) system for three-dimensional structures. An automatic finite element mesh-generation technique, which is based on fuzzy knowledge processing and computational geometry techniques, is incorporated into the system, together with a commercial FE analysis code, and a commercial solid modeler. The system allows a geometry model of interest to be automatically converted to different FE models, depending on the physical phenomena of the structures to be analyzed, i.e., electrostatic analysis, stress analysis, modal analysis, and so on. Also, with the aid of multilayer neural networks, the present system allows us to obtain automatically a design window in which a number of satisfactory design solutions exist in a multi-dimensional design parameter space. The developed CAE system is successfully applied to evaluate an electrostatic micromachines.