• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.726-728
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• 2012

In this paper, the threshold voltage characteristics have been analyzed by varying the channel thicknesses of Double Gate MOSFET. The channel thickness, as well as determining the size of the device which hardly affects SCE(Short Channel Effects), therefore the channel thicknesses is a very important parameter in the IC(Integrated circuit) design. In this study, using series charge distribution to analyze the threshold voltage on the channel thickness. Consequently, the threshold voltage decreases with increasing a channel thickness.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.1
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• pp.53-61
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• 1997

The performance characteristics of magnetic fluid seals are studied numerically as a function of working gap, pole width, angle of pole sharpening, and shaft speed. The temperature distribution of a magnetic fluid seal with multiple tooth is investigated as a function of the contact fraction of magnetic fluids at the periphery of pole tooth using a finite element method. The most significant design parameter of a magnetic fluid seal is the working gap between the pole pieces and the rotating shaft. The result shows that with increasing the working gap, the friction torque decreases radically. The practical working gap for the pole pieces with triangular tooth zone profile is 0.2-0.4mm. The FEM results indicate that the optimal filling of a magnetic fluid between the pole pieces and the shaft is very important due to the accumulations of nonuniform friction heating within the pole pieces, which may interfere the magnetic circuit flow.

• Proceedings of the IEEK Conference
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• 2004.08c
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• pp.796-800
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• 2004

The main research on this paper is to model on-chip inductor in digital CMOS technology by using the foundry parameters and the physical structure. The s-parameters of a spiral inductor are extracted from the modeled equivalent circuit and then compared to the results obtained from HFSS. The structure and material of the inductor used for modeling in this work is identical with those of the inductor fabricated by CMOS process. To show why the modeled inductor instead of ideal inductor should be used to design a RF system, we designed dual band RF front-end receiver and then compared the results between when using the ideal inductor and using the modeled inductor.

• Journal of Electrical Engineering and Technology
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• v.12 no.1
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• pp.472-477
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• 2017

In this work, the current limiting and recovery characteristics of a flux-lock type superconducting fault current limiter (SFCL) with series connection of two coils were effectively improved by adding a third winding into the conventional flux-lock type SFCL with series connection of two coils. To confirm the contribution of the third winding to the current limiting and recovery characteristics of this type of the SFCL, short-circuit testing was carried out with consideration of the third winding, and the effect of the third winding on the current limiting and recovery characteristics was examined by comparative analysis of the amplitude of the limited fault current and the power burden of the high-TC superconducting (HTSC) element comprising the SFCL. Through the analysis of both the limiting impedance and the operational current as the main design parameter of the SFCL, the improved current limiting and recovery characteristics of the flux-lock type SFCL using the third winding could be verified.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.60-65
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• 2001

Bomb calorimeter was developed for measuring the calorific value of combustible matter such as wastes. The calorimeter consist of bomb, stirred-water type bucket, thermometer and ignition circuit. Operation and performance of the calorimeter have been tested experimentally. In the present study, calorific values of light oil, lamp oil and bunker C oil is measured using the bomb calorimeter. Mass of the sample is fixed at lg, and oxygen pressure in the bomb is used as an experimental parameter. Sample in the oxygen bomb is burned with electrically heated Ni-Cr wire of 100mm in length, and temperature of water in the bucket become increased by $5^{\circ}C$ during about 30min. Calorific value of the sample is calculated with the temperature difference of water. Combustion tests, such as the record of temperature history and the inspection of remnants, are performed at 4, 6, 8 and 10 atm of the oxygen pressure. From the test results, oxygen pressure in the bomb must be over 10atm for complete combustion.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.9
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• pp.67-74
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• 2009

For the surge currents like lightning currents containing high frequency components and the abnormal currents having high frequencies which cause the EMI(Electromagnetic interference) problems for the electronic devices and communication instruments, the linear grounding electrodes have the significantly composite impedance characteristics which are dependent on the frequency of the applied current. The impedance of a grounding electrode is not lowered by expanding the dimension of the grounding electrode, and the length of grounding electrode having the minimum value of the grounding impedance for each condition of frequency and soil characteristics is existent, and it is defined as Critical length. In this paper, the critical lengths for the vertically and horizontally-buried grounding electrodes are calculated by using the distributed parameter circuit model. The propriety of the simulations has been confirmed by comparing the simulated results with the measured results.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.4 no.3
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• pp.11-17
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• 1993

An active diplexer can be realized by using a MESFET and 2-sections of asymmetrical coupled bandpass filter, where the admittance inverter parameters in equivalent circuit of asym- metrical coupled microstrip lines are given as a function of an fundamental design parameter of a bandpass filter. An experimental active diplexer was designed over 22 and 18 percent bandwidth centered at 9 GHz and 11 GHz respectively, and the design data was optimized by Super-Compact. The gain performance was $6.2\pm0.3$dB in each band of 8.3~9.6 GHz and 10.3~11.8 GHz The measured bandwidth of the active diplexer was closely matched to design data but measured gain was slightly lower (1.5 dB) than the designed value.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1033-1036
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• 2007

The optical disc drive has used a high NA objective lens and a shorter wavelength laser diode for high recording density. But high NA and shorter wavelength cause several margins to become short. Focusing and tracking servo has to be more accurate and active tilt compensation mechanism is also needed for coma aberration compensation. In this paper, we proposed 3-axis moving magnet type actuator. For 3-DOF motion, moving coil actuator has to equip 6 wires for supplying 3 independent signals. However, moving magnet type actuator doesn't need to change the configuration of wires because coils are in stator. So, we added tilting mechanism to 2-axis moving magnet actuator which is designed in previous research. Addition of the tilting mechanism cuts down the focusing sensitivity. So, maximization the tilting sensitivity and securing the focusing sensitivity are objectivities of this research. DOE (design of experiments) procedures of electromagnetic circuit are performed for parameter study and the optimization is also performed to maximize the tilt sensitivity. And then the final design is suggested and its performance is verified by FE simulation.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.47-50
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• 1991

LPM(Linear Pulse Motor) provide direct and precise position control of bidirectional linear motion. LPM is not subject to the same linear velocity and acceleration limitations inherent in systems converting rotary to linear motion such as lead screws, rack and pinion, belt and pulley drives. With LPM, all the thrust force generated by the motor is efficiently applied directly to the load. And speed, distance, and acceleration are easily programmed in a highly repeatable fashion. Potential industrial and application fields of LPM include PCB assembly, industrial sewing machines, automatic inspection, coil winder, medical uses, conveyer system, laser cut and trim systems, semiconductor wafer processing, OA instruments etc. This paper describes various design parameter of LPM such as magnetic ciucuit construction methods, phase number and tooth number per pole, permanent magnet and coil mmf, tooth geometries. And to solve the problems of existing control methods, in this paper, a new control method of the LPM is proposed throughout modern control theory.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.10
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• pp.3905-3910
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• 2010

In this paper, a 3rd-order Chebyshev current-mode filter in 1.8V-$0.18{\mu}m$ CMOS parameter is designed. The core circuit of the current-mode filter is composed with the proposed voltage-controlled frequency tunable current-mode integrator. Using the proposed current-mode integrator, the cutoff frequency of the filter can be controlled and also total power consumption can be reduced. HSPICE simulation results show the cutoff frequency of the filter is controlled between 1.2MHz and 10.1MHz, and the power consumption is 2.85mW at Vdd=1.8V.