• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.187-192
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• 2006

The effect where the multiple sound arrest ing goes mad to the human being does the zone. From like that cotton, this dissertation the both sides flag executed the research regarding a sound arresting reduction in the object in one example. It compared the piping structure which generally is space-time and a specific piping structure and it tested and research and the modeling regarding a sound arresting reduction the simulation which leads and it executed result and comparison of existing it analyzed. The duplication where the reduction effect is bigger the result general VG2 piping structure than escape it did with the fact that it appears the large effect the piping structure which it connects. Also, the straight pipe effect of multiple sound arresting could not go mad with the fact that.

• Journal of Navigation and Port Research
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• v.28 no.3
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• pp.213-219
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• 2004

In this paper, a LNA(Low Noise Amplifier) has been developed, which is operating at L-band i.e., 1452∼1492 MHz for satellite DAB(Digital Audio Brcadcasting) receiver. The LNA is designed to improve input and output reflection coefficient and VSWR(Voltage Standing Wave Ratio) by balanced amplifier. The LNA consists of low noise amplification stage and gain amplification stage, which make a using of GaAs FET ATF-10136 and VNA-25 respectively, and is fabricated by hybrid method. To supply most suitable voltage and current, active bias circuit is designed Active biasing offers the advantage that variations in $V_P$ and $I_{DSS}$ will not necessitate a change in either the source or drain resistor value for a given bias condition. The active bias network automatically sets $V_{gs}$ for the desired drain voltage and drain current. The LNA is fabricated on FR-4 substrate with RF circuit and bias circuit, and integrated in aluminum housing. As a reults, the characteristics of the LNA implemented more than 32 dB in gain. 0.2 dB in gain flatness. lower than 0.95 dB in noise figure, 1.28 and 1.43 each input and output VSWR, and -13 dBm in $P_{1dB}$.

• 유공압시스템학회:학술대회논문집
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• 2010.06a
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• pp.12-17
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• 2010

The poppet valve had used every field area due to high quality of leakage property and response characteristic. But this valve still has terrible disadvantage that is self-exited vibration. This problem affects stability of total system and raises noise. The researcher tries to reduce that self-exited vibration when valve was designed. The stability discriminant is the typical study to improve the performance of the poppet valve. This paper concerns about stability discriminant that uses poppet valve with a drain orifice. At the first, the mathematical model is computed from poppet valve. After that, the limitation of stability is calculated that based on Nyquist criterion. At the final, the stability discriminant is selected in each condition and the graph that shows stability in the system is drown by dimensionless quantity.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.7
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• pp.761-766
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• 2014

This study performs the analytical investigation of the oscillation voltages at the tanks of the series tuned varactor incorporating balanced common-drain, and common-gate Colpitts VCO which are able to work even at the sub-1V power supply voltages. The results the investigation predicts is verified by the simulation on the circuit behaviors of the two VCOs. The analytical investigation finds that the series tuned varactor incorporating balanced common-gate VCO generates greater oscillation voltage at the tank than the series tuned varactor incorporating balanced common-drain VCO does, which in turn is more suitable for generating the low phase noise oscillation signal from the sub-1V supply voltage than the series tuned varactor incorporating balanced common-drain VCO.

• Journal of Power Electronics
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• v.2 no.2
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• pp.139-145
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• 2002

Because conventional switching converters have been usually using unbalanced circuit topologies, parasitice between the drain/collertor of an active switch and frame ground through its heat sink may generate the commom-mode conducted noise. We have proposed a balanced switching converter circuit, whitch is an effective way to reduce the commom-mode converter version of the balanced switching converter was presented and the mechanism of the commom-mode noise reduction was explained using equivalent circuits. This paper extends the concept of the balanced switch converter circuit and presents a buck-boost converter version of the blanced switching converter. The feature of common-mode niose reduction is confirmed by experimental resuits and the mechanisem of the commom-mode niose reduction is explained using equivalent circuits.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.11
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• pp.89-94
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• 2011

In this paper, we developed the W-band MMIC low noise amplifier for the millimeter-wave seeker using the tuner system. The MHEMT devices for MMIC LNA exhibited DC characteristics with a drain current density of 692mA/mm, an extrinsic transconductance of 726mS/mm. The current gain cutoff frequency(fT) and maximum oscillation frequency($f_{max}$) were 195GHz and 305GHz, respectively. The fabricated W-band low noise amplifier represented S21 gain of 7.42dB at 94 GHz and noise figure of 2.8dB at 94.2 GHz.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.3
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• pp.1-8
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• 2004

The anomalous behavior of the 1/f noise of halo or pocket ion implanted MOSFETs is investigated. The model for the anomalous 1/f noise behaviors of MOSFETs, which consist of inhomogeneous conductance along the channel is improved within a regional approximation as previous works and presented in a fen directly applicable to halo MOSFETs. The presented model reduces to the previous results, discussed in the linear region operation, for small drain bias. Comparisons with experimental results show that the 1/f model based on the regional approach can be applicable for limited ranges, especially for sufficiently large gate bias voltages.

• Journal of the Korean Institute of Telematics and Electronics
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• v.19 no.1
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• pp.9-13
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• 1982

The purpose of this experiment is to evaluate the noise dependency on the gate dimensions of the P-ch MOSFET which is fabricated of p+ sourse, drain, and gate electrode doped with PH$_3$ gas in type-N Si sudstrate. Experimental results indicate that: for the constant gate area and reletively thick films, noise level tends to decrease for the W/L ratio over unity, which generally conforms with theoretical observations, but its variation with the change in the thickness of film is less than the theoretically predicted for the W/L ratio below unity.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05c
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• pp.148-152
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• 2001

One set of MMIC library has been developed using gate recess etching by spin processor. It is superior than that of dipping Method in the uniformity and the reproducibility of gate recess. A DC characteristics of p-HEMT have a uniform characteristics in the whole wafer than that of dipping method. The low noise p-HEMT with the $0.6{\mu}m$ and $200{\mu}m$ of gate length and gate width, respectivily, has a uniform characteristics of Idss 130~145 mA, conductances 190~220mS/nm, and threshold voltage -0.7~-1.1V in the drain voltage of 2V.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.3
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• pp.113-123
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• 1989

We developed a general algorithm and program to determine nominal value of new optimum geometric parameters of MOSFET when yield satisfying specification of drain current and noise spectral density is maximum. In this paper, the total number of considered devices is 500, and each parameters of geometric parameter was generated randomly within the limits of ${pm}3%$ of nominal value, and the distribution of 500 geometric parameters is gaussian distribution.