• 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.

• 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.

• 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 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 IKEEE
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• v.2 no.1 s.2
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• pp.15-23
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• 1998

In this paper, distributed mixer is studied at microwave frequency. The circuit of distributed mixer composed of gate 1,2, drain transmission lines, matching circuits in input and output terminal, DGFET's. For impedance matching of input and output port at higher frequency, image impedance concept is introduced. In distributed mixer, a DGFET's impedances are absorbed by artificial transmission line, this type of mixer can get a very broadband characteristics compared to that of current systems. A RF/LO signal is applied to each gate input port, and are excited the drain transmission line through transcondutance of the DGFET's. The output signals from each drain port of DGFET's added in same phases. We designed and frabricated the distributed mixer, and a conversion gain, noise figure, bandwidth, LO/RF isolation of the mixer are shown through computer simulation and experimentation.

• Journal of Sensor Science and Technology
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• v.6 no.3
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• pp.194-199
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• 1997

When voltage or current gets out of the magnetic sensor as it is, we have often faced the problems such as introduction of noise and loss of voltage. In order to reduce these problems, a 2 drain MAGFET operating in the saturation region and fabricated by CMOS process, the system of I/V converter, VCO with operational amplifier, and V/F conversion circuits with Schmitt Trigger are designed and fabricated in one package. The absolute sensitivity of magnetic sensor shows 1.9 V/T and the product sensitivity is $3.2{\times}10^{4}\;V/A{\cdot}T$. The characteristic of V/F conversion is very stabilized and has the value of 190 kHz/T.

• JSTS:Journal of Semiconductor Technology and Science
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• v.11 no.3
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• pp.169-181
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• 2011

In this present paper, a comprehensive drain current model incorporating the effects of channel length modulation has been presented for multi-layered gate material engineered trapezoidal recessed channel (MLGME-TRC) MOSFET and the expression for linearity performance metrics, i.e. higher order transconductance coefficients: $g_{m1}$, $g_{m2}$, $g_{m3}$, and figure-of-merit (FOM) metrics; $V_{IP2}$, $V_{IP3}$, IIP3 and 1-dB compression point, has been obtained. It is shown that, the incorporation of multi-layered architecture on gate material engineered trapezoidal recessed channel (GME-TRC) MOSFET leads to improved linearity performance in comparison to its conventional counterparts trapezoidal recessed channel (TRC) and rectangular recessed channel (RRC) MOSFETs, proving its efficiency for low-noise applications and future ULSI production. The impact of various structural parameters such as variation of work function, substrate doping and source/drain junction depth ($X_j$) or negative junction depth (NJD) have been examined for GME-TRC MOSFET and compared its effectiveness with MLGME-TRC MOSFET. The results obtained from proposed model are verified with simulated and experimental results. A good agreement between the results is obtained, thus validating the model.