• IEIE Transactions on Smart Processing and Computing
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• v.4 no.3
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• pp.149-151
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• 2015

Coupling with a ring of capacitors introduces in-phase coupling current in multi-stage LC oscillators, increasing coupling strength and phase spacing accuracy. Capacitive coupling is effective at high-frequency applications because it increases coupling strength with the operating frequency. However, capacitive loading from the ring lowers operating frequency and reduces the tuning range. Mathematical expressions of phase noise and phase spacing accuracy with capacitive coupling are examined here, and transistor-level simulations confirm the effectiveness of the capacitive coupling.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.2
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• pp.201-208
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• 1999

This paper presents the degradation of the system performance according to the vmiation of the rotor time constant. The algorithm for the on-line estimation of rotor time constant is proposed. which is applied to the consistent relationship between the tangent torque angle of the synchronous reference frame and that of stationary reference f frame. For the purpose of the validity of proposed algorithm. the computer simulation and the experiments have been p performed.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.69-74
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• 2001

In this Paper are described the indirect induction heated boiler and induction heated hot air producer using the voltage-fed series resonant high-frequency inverter which can operate in the frequency range from 20kHz to 50kHz. A specially designed induction heater, which is composed of laminated stainless assembly with many tiny holes and interconnected spot welding points between stainless plates, is inserted into the ceramic type vessel with external working coil. This working coil is connected to the inverter and turbulence fluid through this induction heater to moving fluid generates in the vessel. The operating performances of this unique appliance in next generation and its effectiveness are evaluated and discussed from a practical point of view.

• Korean Journal of Optics and Photonics
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• v.7 no.3
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• pp.244-249
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• 1996

Multipass Ti:sapphire amplifier for the light source of DIAL was developed with an angular-multi-plexing, and the characteristics of output energy and spectra were investigated. As the characteristics of two-stage multipass amplifier, the maximum output energy was 22 mJ and the amplification gain was 20 dB on the wavelength of 790 nm. At that condition, output efficiency of the pumping energy was 18 percent. We obtained $0.15cm^{-1}$ (9.4 pm) as a spectral linewidth in the tuning range of 705~845 nm.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.5
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• pp.15-24
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• 1997

We propose a tunable add/drop filter in a form of an all-fiber mach-zehnder interferometer iwth one bragg grating at each arm. This device can be tuned by inducing a strain in the bragg grating. We also theoretically analyze the outut characteristics of the tunable add/drop filter. As a result of simulation, we know that the proposed tunable add/drop filter works well. When 2*10$^{-3}$ of strain is induced, the reflected spectrum shifts about 3nm. And its reflected spectral width is about 0.3nm. In this case roughly 5 channels can be tuned, assuming the channel spacing is 0.3nm. When the pathlengths of the both arms are not the same, the transmissivities at the add and output ports and the reflectivity at the tap port varies sinusoidally with the pthlength difference. To maintain the transmissivities above 90% in the wavelength tuning range of 20nm the pathlength difference less than 16.mu.m is required.

• Journal of electromagnetic engineering and science
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• v.3 no.1
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• pp.29-34
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• 2003

In this paper, we fabricated an 1.8 ㎓ differential VCO using a commercial 0.5 ${\mu}{\textrm}{m}$ SiGe BiCMOS process technology, The fabricated VCO consumes 16 ㎃ at 3 V supply voltage and has a 1.2 $\times$ 1.6 $mm^2$TEX>chip area. A phase noise measured at 100 KHz offset carrier is -110 ㏈c/Hz and a tuning range is 1795 MHz~1910 MHz when two varactor diodes are biased from 0 V to 3 V.

• JSTS:Journal of Semiconductor Technology and Science
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• v.12 no.3
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• pp.255-265
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• 2012

This paper presents a 15-GHz multiphase rotary traveling-wave voltage-controlled oscillator (RTW VCO) where a shielded coplanar stripline (CPS) is exploited to provide better shielding protection and lower phase noise at a moderate cost of characteristic impedance and power consumption. Test chips were implemented in a standard 90-nm CMOS process, demonstrating the measured results of 2-GHz frequency tuning range, -11.3-dBm output power, -109.6-dBc/Hz phase noise at 1-MHz offset, and 2-ps RMS clock jitter at 15 GHz. The chip core occupies the area of $0.2mm^2$ and dissipates 12 mW from a single 1.2-V supply.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.622-625
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• 2007

For optimizing the performance of SI engine such as engine torque, fuel consumption, and emissions, systems for variable valve timing were developed by many automotive researchers. In this work, we investigated the relationship between valve timing and intake orifice noise to improve the NVH (Noise, Vibration and Harshness) performance as well as engine torque and power. Two approaches are conducted, which are engine dynamometer testing and 1-D simulation analysis. Experimental data were measured on about 21 different operating conditions. This experiment shows that the intake and exhaust valve timing related to overlap period influence on the NVH performance, especially intake orifice noise of engine at given range of operation conditions. Similar results are achieved by using 1-D simulation analysis. It is concluded that the optimal strategies of controlling valve timing and tuning intake systems, are necessary to develop engines or vehicles with good sound quality.

• Journal of the Korea Computer Industry Society
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• v.2 no.8
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• pp.1063-1068
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• 2001

In this paper, we designed a high resolution six channel DSB modulator of Acousto-Optic effect generator make use of DDS technology. Also, configured seamless connection for other instruments to use IEEE-488 bus interface. We programmed the device driver for DDS and DAC control by 80C51 assembler language. And, high resolution 6 channel DSB modulator has improved the important characteristics of that the frequency tuning range, the resolution, the switching time. This DSB modulator system can use high precision frequency synthesizer for instruments.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.419-423
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• 2003

In this paper, we have constructed singly resonant KTP OPO system pumped by 532 nm to obtain broadly frequency tunable pulses. Also we have mathematically simulated frequency tuning range, phase matching angle for 900 nm output and threshold energy, and we calculated output intensity using wave propagation equations for optical parametric oscillator which include walk-off, pump depletion.