• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.102-108
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• 2000

Due to the rapid increase of long-distance transportation, particular attentions have been paid to truck tires, especially to their dynamic characteristics. In this research, experimental modal analysis on two kinds of light-truck tires, i.e., radial tire and bias tire, are performed by using GRFP(global rational fraction polynomial) method to investigate differences of the dynamic behavior of the two tires. The test results have shown that the modal frequencies of bias tire are much higher than their corresponding values of radial tire with a similar mode shape, which is in accordance with the fact that the radial rigidity of bias tire is higher than that of radial tire. And most of the modal decay rates of bias tire are larger than those of radial tire within the scope of this experiment. In the frequency domain range of test, the bias tire has extra modes, which do not occur in the radial tire. This difference is based on the fact that the circumferential rigidity of the bias tire is quite low whereas that of radial tire is so high that the frequencies of the corresponding modes are out of the frequency range of test.

• The Korean Journal of Applied Statistics
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• v.16 no.2
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• pp.305-319
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• 2003

This paper provides a non-Bayesian method based on the expanded EM algorithm for segmenting the magnetic resonance images degraded by bias field. For the images with the intensity as a pixel value, many segmentation methods often fail to segment it because of the bias field(with low frequency) as well as noise(with high frequency). Our contextual approach is appropriately designed by using normal mixture model incorporated with Markov random field for noise-corrective segmentation and by using the penalized likelihood to estimate bias field for efficient bias filed-correction.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.513-514
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• 2005

In plasma processing reactors, it is common practice to control plasma density and ion bombardment energy by manipulating excitation voltage and frequency. In this paper, a dually excited capacitively coupled rf plasma reactor is self-consistently simulated with a three moment model. Effects of phase differences between primary and secondary voltage waves, simultaneously modulated at various combination of commensurate frequencies, on plasma properties are investigated. The simulation results show that plasma potential and density as well as primary self-dc bias are nearly unaffected by the phase lag between the primary and the secondary voltage waves. The results also show that, with the secondary frequency substantially lower than the primary frequency, secondary self-dc bias remains constant regardless of the phase lag. As the secondary frequency approaches to the primary frequency, however, the secondary self-dc bias becomes greatly altered by the phase lag, and so does the ion bombardment energy at the secondary electrode. These results demonstrate that ion bombardment energy can be more carefully controlled through plasma simulation.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.8
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• pp.1263-1268
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• 2008

In this paper, the low noise power amplifier for GaAs FET ATF-10136 is designed and fabricated with active bias circuit and self bias circuit. To supply most suitable voltage and current, active bias circuit is designed. Active biasing offers the advantage that variations in the pinch-off voltage($V_p$) and saturated drain current($I_{DSS}$) will not necessitate a change in either the source or drain resistor value for a given bias condition. The active bias network automatically sets a gate-source voltage($V_{gs}$) for the desired drain voltage and drain current. Using resistive decoupling circuits, a signal at low frequency is dissipated by a resistor. This design method increases the stability of the LNA, suitable for input stage matching and gate source bias. The LNA is fabricated on FR-4 substrate with active and self bias circuit, and integrated in aluminum housing. As a results, the characteristics of the active and self bias circuit LNA implemented more than 13 dB and 14 dB in gain, lower than 1 dB and 1.1 dB in noise figure, 1.7 and 1.8 input VSWR at normalized frequency $1.4{\sim}1.6$, respectively.

• Proceedings of the IEEK Conference
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• 2001.06b
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• pp.193-196
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• 2001

One of the major reasons for not integrating a VCO on one-chip in a PLL (phase locked loop) system is the large chip-to-chip variation of the VCO (voltage controlled oscillator) center frequency. In this thesis, a simple bias technique is proposed to compensate the process fluctuation. The proposed bias technique is applied to the VCO and it reduces the deviation of the VCO center frequency from 35% to 8 %. With the suggested bias technique, a 400 MHz frequency synthesizer is designed for general purpose. It utilizes a programmable divider for various division ratio. The design methodology provides the possibility of the one-chip solution for a PLL system.

• Journal of the Semiconductor & Display Technology
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• v.19 no.4
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• pp.88-93
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• 2020

Based on the capture-emission energy (CEE) maps of CMOS devices, a physics-informed machine learning model for the bias temperature instability (BTI)-induced threshold voltage shifts and low frequency noise is presented. In order to incorporate physics theories into the machine learning model, the integration of artificial neural network (IANN) is employed for the computation of the threshold voltage shifts and low frequency noise. The model combines the computational efficiency of IANN with the optimal estimation of Gaussian mixture model (GMM) with soft clustering. It enables full lifetime prediction of BTI under various stress and recovery conditions and provides accurate prediction of the dynamic behavior of the original measured data.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.4
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• pp.101-108
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• 1998

We examine experimentally the dependence of output width on DC bias, RF power, and RF frequency in a gain-switched semiconductor laser. The optimum short pulses are obtained around threshold DC bias. The DC bias to generatoe shorter pulses decreases the RF power increases, whereas it increases to above threshold as the RF freqnecy increases. The pulse width becomes less sensitive to the variations of the DC bias, as the RF bias, or frquency increases.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.45-48
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• 2000

By the use of he DSP and microprocessor controller many high power converter such as especially inverter and motor drive system may be enhanced resulting in the improved robustness of EMI the ability to communicate the operating conditions and the ease of adjusting the control parameters. However the digital controller using DSP or microprocessor has not been applied in the high frequency switching power supplies especially in full bridge dc/dc converters. this paper presents a promising solution to the dc bias control problem of high frequency transformer in high power full bridge converter.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.492-492
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• 2012

RF biased inductively coupled plasma (ICP) has been widely used in various semiconductor etching processes and laboratory plasma researches. However, almost researches for the RF bias have been focused on the controls of dc self-bias voltages, even though the RF bias can change plasma parameters, such as electron temperature, plasma density, electron energy distribution (EED), and their spatial distributions. In this study, we report on the effect of the RF bias on the plasma parameters and the EEDs with various external parameters, such the RF bias power, the ICP power, the gas pressure, the gas mixture, and the frequency of RF bias. Our study shows the correlation between the RF bias and the plasma parameters and gives a crucial key for the understanding of collisionless electron heating mechanism in the RF biased ICP.

• JSTS:Journal of Semiconductor Technology and Science
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• v.9 no.4
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• pp.192-197
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• 2009

This paper presents the design and measurement of a 2.4/5.2-GHz dual band VCO with a balanced frequency doubler in $0.18\;{\mu}m$ CMOS process. The topology of a 2.4 GHz VCO is a cross-coupled VCO with a LC tank and the frequency of the VCO is doubled by a frequency balanced doubler for a 5.2 GHz VCO. The gate bias matching network for class B operation in the balanced doubler is adopted to obtain as much power at 2nd harmonic output as possible. The average output powers of the 2.4 GHz and 5.2 GHz VCOs are -12 dBm and -13 dBm, respectively, the doubled VCO has fundamental harmonic suppression of -25 dB. The measured phase noises at 5 MHz frequency offset are -123 dBc /Hz from 2.6 GHz and -118 dBc /Hz from 5.1 GHz. The total size of the dual band VCO is $1.0\;mm{\times}0.9\;mm$ including pads.