• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.5
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• pp.96-100
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• 2007

Condenser lens and objective lens are used to demagnify the image of the crossover to the final spot size. In lens, electrons are focused by magnetic fields. This fields is fringing field. It is important in electron focusing. Electron focusing occurs the radial component field and axial component field. Radial component produces rotational force and axial component produces radial force. Radial force causes the electron's trajectory to curve toward the optic axis and corss it. Focal length decreases as the current of lens increases. In this paper, we use the focal length for desiging the hardware of lens current control and present the results.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.561-563
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• 2012

In this work, tunable capacitors using a finger-type electrode are designed and characterized for frequency-agile RF circuit applications. Their top electrodes with different area and line width are designed in types of the finger for a long conducting perimeter which results in enhanced fringing-electric fields in order to improve their tunability. The tunable varactors were fabricated on a quartz substrate employing a multi-layer dielectric of a para/ferro/para-electric thin film. Compared to the conventional capacitor, finger-type capacitors are characterized in terms of effective capacitance and tunablility. Their effective capacitance and tunability with the long perimeter increase 24~40% and 7~12%, respectively, due to enhanced fringing electric fields from 1 to 2.5 GHz, compared to the conventional ones.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.640-643
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• 2008

In this work, a novel tunable MIM capacitor with the meshed electrode is proposed first in order to improve the tunability characteristics using fringe fields. The capacitors were fabricated on a low-resistivity Si substrate employing lead zinc niobate (PZN) thin film dielectric. The fabricated capacitor with the meshed electrode, whose line width and spacing was $2.5{\mu}m$, achieved the effective capacitance tunability of 31 % that is higher value of 18.5 % than that of the conventional capacitor with the rectangular-type electrode.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.11
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• pp.25-31
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• 1990

We analyze the spherical-rectangular patch microstrip resonator with conformal surface by the cavity model and derive the formulas to calculate resonant frequency in the consideration of effective dielectric constant in order to minimize the errors of resonant frequency due to the fringing fields. A transmission type spherical-rectangular patch microstrip resonator operating at 3GHz, for example, is designed and fabricated on Epsilam-10 substate. Measuring data of resonant frequency and return loss are 2.985 GHz and -44.4dB respectively. Those well agreed with theoretical values.

• Journal of Electrical Engineering and Technology
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• v.9 no.4
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• pp.1343-1348
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• 2014

The low frequency noise in Silicon Nanowire Field Effect Transistors is analyzed by characterizing the gate electrode dependence on various geometrical parameters. It shows that gate electrodes have a strong impact in the flicker noise of Silicon Nanowire Field effect transistors. Optimization of gate electrode was done by comparing different performance metrics such a DIBL, SS, $I_{on}/I_{off}$ and fringing capacitance using TCAD simulations. Molybdenum based gate electrode showed significant improvement in terms of high drive current, Low DIBL and high $I_{on}/I_{off}$. The noise power sepctral density is reduced by characterizing the device at higher frequencies. Silicon Nanowire with Si3N4 spacer decreases the drain current spectral density which interms reduces the fringing fields there by decreasing the flicker noise.

• Journal of Advanced Navigation Technology
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• v.17 no.6
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• pp.720-725
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• 2013

This paper has presented that fringing-electric fields enhanced by a finger-type electrode can improve the tunability of the tunable capacitor. Its top electrodes with different area and line width are designed in types of the finger for a long conducting perimeter. The tunable varactors were fabricated on a quartz substrate employing a multi-layer dielectric of a para/ferro/para-electric thin film. Compared to the conventional capacitor, finger-type capacitors are analyzed in terms of effective capacitance and tunablility. Their effective capacitance and tunability of the varactors with the long perimeter increase 24~40 % and 7~12 %, respectively, due to enhanced fringing electric fields from 1 to 2.5 GHz.

• Journal of the Institute of Convergence Signal Processing
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• v.4 no.1
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• pp.41-48
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• 2003

In this paper, a new equivalent circuit for a defected ground structure(DGS) is proposed and adapted to design of a power amplifier for performance improvement. The DGS equivalent circuit presented in this paper consists of parallel LC resonator and parallel capacitance to describe the fringing fields due to the etched defects on the metallic ground plane, and also is used to optimize the matching circuit of a power amplifier. A previous research has also used a DGS for harmonic rejection and efficiency improvement of a power amplifier(1), however, there was no exact equivalent circuit analysis. In this paper, we suggest a novel design method and show the performance improvement of a class AB power amplifier by using the equivalent circuit of a DGS applied to output matching circuit. The design method presented in this paper can provide very accurate design results to satisfy the optimum load condition and the desirable harmonic rejection, simultaneously. As a design example, we have designed a 20W power amplifier with and without circuit simulation of DGS, and compared the measurement results.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.401-404
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• 2004

The electron beam machining provides very high resolution up to nanometer scale, hence the E-beam writing technology is rapidly growing in MEMS and nano-engineering areas. In the optical column of the e-beam writer, there are several lenses condensing and focusing electron beams from electron gun with fringing magnetic fields. To achieve small spot size as 1-2 nm for higher power of electron beam, magnetic lenses should be designed considering their magnetic field distribution. In this paper, the magnetic field at two condenser lenses and object lens are calculated with finite element method and discussed its performances.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.586-589
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• 2012

In this paper, a tunable capacitor like an interdigital one is presented for low-voltage applications. In order to reduce operation voltage by enhancing fringing electric fields, two finger-patterned electrodes are vertically separated by employing a multi-layer thin film dielectric of a para-/ferro-/para-electrics without spacing between electrodes. The proposed tunable capacitor was fabricated on a quartz wafer and its characteristics are analyzed in terms of effective capacitance and tunability with a function of applied voltages, compared to the conventional interdigital capacitor (IDC). At 8V and 2 GHz, the proposed tunable capacitor shows the tunability of 18 % that is 10.3 % higher than that of the compared one.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.149-153
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• 2005

The electron beam machining provides very high resolution up to nanometer scale, hence the E-beam writing technology is rapidly growing in MEMS and nano-engineering areas. In the optical column of the e-beam writer, there are several lenses condensing and focusing electron beams from electron gun with fringing magnetic fields. The polepieces of these lenses are usually made with high purity iron which is hard to fabricate and very expensive. In this paper, the possibility of using polepiece of object lens composed with pure iron and low carbon steel was examined to reduce cost. The magnetic field at object lens was calculated with finite element method, and practical focusing qualities of SEM pictures were observed comparing for the object lens polepieces with pure iron and two type of composed with low carbon steel.