• 제어로봇시스템학회:학술대회논문집
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• 1995.10a
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• pp.87-90
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• 1995

When the ultrasonic transducer operating at l MHz for use in cleaning semiconductor wafers or other industsrial materials is driven from the MOS-FET DC-to RF inverter, the output power severely depends on the frequency of operation since the quality factor of the transducer is high. In order to tune to the eresonating frequency of the ultrasonic transducer, the drive signal frequency of the MOS-FET power inverter is automatically scananed until the frequency is set at the resonating frequency of the ultrasonic transducer is maximized. The control circuit consists of an output power sensing circuit, a PLL controller, a frequency standard, and other peripheral circuits. The operation was satisfactory when the transducer having an output of 600 W at 1 MHz was used.

• 한국정보통신설비학회:학술대회논문집
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• 2008.08a
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• pp.414-417
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• 2008

This paper presents the design and analysis of 2.45GHz Low-IF Mixer using CMOS 0.18um. The Mixer is implemented by using the Gilbert-type configuration, current bleeding technique, and the resonating technique for the tail capacitance. And the design of this Double Balance Mixer is based on its lineaity since it is important in the interference cancellation system. The low flicker noise mixer is implemented by incorporating a double balanced Gilber-type configuration, the RF leakage-less current bleeding technique, and Cp resonating technique. The proposed mixer has a simulated conversion gain of 16dB a simulated IIP3 of -3.3dBm and P1dB is -19dBm. A simulated noise figure of 6.9dB at l0MHz and a flicker corner frequency of 510kHz while consuming only 10.65mW od DC power. The layout of Mixer for one-chip design in a 0.18-um TSMC process has 0.474mm$\times$0.39 mm size.

• Journal of Sensor Science and Technology
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• v.20 no.4
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• pp.238-242
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• 2011

This paper describes the fabrication and characteristics of a low frequency vibration driven electromagnetic energy harvester. The fabricated generator consists of a permanent magnet of NdFeB, a FR-4 planar spring and a Copper cylinder type coil. ANSYS modal analysis was used to determine the resonant frequency for the generator. The implemented generator is capable of producing up to 550 mV peak-to-peak under 7 Hz frequency, which has a maximum power of $95.5\;{\mu}W$ with load resistance of $580\;{\Omega}$. This device is shown to generate sufficient power at different resonating modes, and the experimental and simulated results are discussed and composed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.5
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• pp.680-687
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• 1999

An extensive study on miniaturized bandpass filter(BPF) appropriate for mobile communication systems is presented in this paper. The miniaturization has been accomplished by incorporating low-loss high-index materials inside a resonating cavity fabricated in silicon substrate using micromachining etching techniques. By use of materials with dielectric constant $\varepsilon_r$=500, filters with volume less than 0.11 $mm^3$ have been designed at the center frequency of 5.8 GHz with 3.3% bandwidth. The electrical performances and design tolerances of these filters for a variety of materials and shapes are discussed and design guidelines are presented herein.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.291-294
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• 1999

This paper presents a GaAs MESMET self oscillating mixer for high efficiency L-band frequency conversion with small chip area consumption. Main circuit topology is consist of cascoded two FET with resonating part. The circuit is designed as unstably nonlinear for limited frequency band. FET with drain shorted to source is used for frequency tuning element. Linear conversion gain of -18.83 ㏈ is achieved with 9mA and 4V consumption. Input 1㏈ compression point is more than 11㏈m. The chip area is 1.4$\times$1.4 mm.

• Journal of electromagnetic engineering and science
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• v.11 no.4
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• pp.298-303
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• 2011

A capsular endoscope (CE) for inspection of the large intestine requires a motor for backward navigation against the autonomous travel in the intestine. This study proposes an HF power system for generating a magnetic field and for delivering wireless power to the internal or implanted medical devices. The magnetic field is generated by a wound coil (L) around a wooden frame, and the current is driven to the coil through a resonating capacitor (C). The characteristics of the resonance frequency shifting of the L-C series circuit are analyzed. A stable magnetic field intensity in the field coil is maintained by a specially designed frequency tracking system that automatically follows the L-C resonance frequency. Testing confirmed that the oscillation system tracks well the parameter changes of the electric components caused by the operating conditions or environmental variations.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.697-700
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• 1999

This Paper presents the design, fabrication, analysis of the measured date of a voltage controlled oscillator(VCO) for the application of Personal Communication Systems. Main VCO circuit consists of self biased emitter resonating circuit with microstrip line resonator on FR4 epoxy substrate. A varactor diode is used for 90MHz frequency tuning with center frequency of 1635MHz Phase noise of -114.67㏈C/Hz at 100KHz off set has been achieved with 3.3 V supply. The size of the fabricated VCO circuit is 1.25 cm$\times$ 1.25 cm.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.11
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• pp.1982-1987
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• 2007

This paper presents the design and analysis of LNA-Mixer for 2.45GHz RFID reader. The LNA is implemented by PCSNIM method for low power consumption. The Mixer is implemented by using the Gilbert-type configuration, current bleeding technique and the resonating technique for the tail capacitance. The connection between the two designed circuits is made by active balun. This LNA-Mixer has about 22dB gain and 8.5dB Noise Figure for -50dBm input RF power, LO power is 0dBm, RF frequency is 2.45 GHz and IF frequency is 100kHz. The layout of LNA-Mixer for one-chip design in a 0.18-um TSMC process has $2.5mm{\times}1.0mm$ size.

• Journal of the Korean institute of surface engineering
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• v.50 no.5
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• pp.392-397
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• 2017

The Young's modulus of a nanoscale titanium (Ti) thin-film was evaluated using a high-speed microcantilever resonating at the megahertz frequency in the present study. A 350 nm thick Ti film was deposited on the surface of a silicon microcantilever, and the morphology of the film was analyzed using the atomic force microscopy. The microcantilever was excited to resonate using an ultrasonic pulser that generates tone burst signals and the resonance frequency shift induced by the deposition of Ti was measured using a Michelson interferometer. The Young's modulus was determined through a modal analysis using the finite element method and the result was validated by the nanoindentation testing, showing good agreement within a relative error of 1.0%. The present study proposes a nanomechanical characterization technique with enhanced accuracy and sensitivity.

• Current Optics and Photonics
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• v.5 no.3
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• pp.213-219
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• 2021

We describe a single-channel rubidium (Rb) radio-frequency atomic magnetometer (RFAM) as a receiver that takes magnetic signal resonating with Zeeman splitting of the ground state of Rb. We optimize the performance of the RFAM by recording the response signal and signal-to-noise ratio (SNR) in various parameters and obtain a noise level of 159 $fT{\sqrt{Hz}}$ around 30 kHz. When a resonant radiofrequency magnetic field with a peak amplitude of 8.0 nT is applied, the bandwidth and signal-to-noise ratio are about 650 Hz and 88 dB, respectively. It is a good agreement that RFAM using alkali atoms is suitable for receiving signals in the very low frequency (VLF) carrier band, ranging from 3 kHz to 30 kHz. This study shows the new capabilities of the RFAM in communications applications based on magnetic signals with the VLF carrier band. Such communication can be expected to expand the communication space by overcoming obstacles through the high magnetic sensitive RFAM.