• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.852-855
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• 2008

In this paper, we proposed a new type's PZT actuator using surface acoustic wave. This actuator uses Rayleigh wave as an operational traveling wave. For the development of the actuator, each components of surface acoustic wave motor like PZT substrate, slider and IDT was studied theoretically and fabricated. For the measurement of transfer function of PZT substrate and operation of surface acoustic wave motor, network analyzer and 13.56MHz RF generator were used. Also the model which expresses the driving characteristic best was suggested and simulation was executed for the suggested model. And the future research works for improvement of SAW actuator was suggested.

• YAKHAK HOEJI
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• v.6 no.2
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• pp.1-6
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• 1962

Clinical tests revealed that the extracts of Gelidium amansii (Gelidiaceae) had a anthelmintic action and further examinations were made on the anthelmintic components of this seaweed. This anthelmintic principle is absorbed on alumina and eluted from it by alkali solution. The active principle is absorbed on activated carbon from aqueous extract and eluted from it by methanol and it is not adsorbed on Amberite IR-120(H-form). This anthelmintic effective fraction was prepared by the use of this properties. Action of the active principle of Gelidium amansii was examined pharmacologically. The active principle of Gelidium amansii was found to decrease the tensity, tonus and mobility of Eisenia foetida(Savigny) nerve muscles. The active principle of this effective fraction was submitted to paper chromatography and spots to ninhydrin were detected at Rf; 0.30-0.31(yellow), 0.26(violet), 0.2(violet), 0.14-0.13(violet), 0.9(orange) and 0.04(violet).

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.96-99
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• 2003

This paper presents the development of a Ku-band Low Noise Amplifier with the Noise figure of 1.4dBmax, the gain of 35dB, and the In/Out Return toss of -22dB/-18dB in the frequency range from 14 to 14.5GHz for Satellite transponders. All RF components were assembled using a hybrid technology with 15-mil thin-film substrates. The mechanical and thermal design of the housing was performed considering a vibration and a vacuum of space environment.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.04b
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• pp.150-152
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• 2004

The number of layers in rigid PCB(printed circuit board) is restricted, so the number of components can be embedded in module is restricted also. But using flexible multilayer PCB, the layers over than 7 can be evaluated. In this study, to verify the possibility of application of flexible multilayer PCB to RF modules, multilayered embedded capacitor is fabricated and analyzed. The characteristics of embedded capacitor is analyzed and compared to that of MLCC and LTCC capacitor. Embedded capacitor has better electrical features than MLCC and compatible one to LTCC capacitor.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1434-1435
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• 2008

In this paper, we propose a method that applies Vector Fitting(VF) and Adaptive Frequency Sampling(ASF) technique to the equivalent circuit model for RF passive components. VF and ASF schemes are implemented to obtain the rational functions. S parameters of the equivalent circuit model is compared to those of EM simulation in case of the microstrip structure with coupled bandpass filter.

• Journal of Advanced Navigation Technology
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• v.2 no.1
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• pp.11-21
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• 1998

There have been active research efforts in the development of a dual-use millimeter-wave radiometer as an aircraft landing aid in low visibility conditions. In this paper, we constructed a radiometer operating at the Ka-band where it is relatively easy to build RF components. The radiometer is used to collect radiometric signatures of some vehicles and land surfaces. Measured signatures suggest that vehicles with metallic surfaces yield signatures markedly different from nearby land surfaces so that they can easily be detected by a simple radiometer.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.06a
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• pp.406-411
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• 2005

In this paper, we propose an active 90$^{\circ}$ phase divider for application to MMIC. Because of their very large size, conventional passive 90$^{\circ}$ dividers can't be integrated on MMIC. Therefore, highly miniaturized 90$^{\circ}$ dividers are required for a development of highly integrated MMIC. For this reason, active 90$^{\circ}$ divider is indispensable because active phase divider is much smaller than conventional passive dividers, and it can be integrated on MMIC. In this work, we developed active 90$^{\circ}$ divider with emitter inductor, and it was employed for the operation of the balanced mixer in order to verify the performance of the active 90$^{\circ}$ divider. According to the results, it was found that the active 90$^{\circ}$ divider exhibited good RF performances comparable to conventional passive power dividers.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.06a
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• pp.412-416
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• 2005

In this paper we propose low-impedance and miniaturized a wilkinson power divider on MMIC passive component which was fabricated by a novel microstrip line structure employing periodically perforated ground metal (PPGM). The novel microstrip line structure showed much lower impedance and shorter guided-wavelength than conventional one. Using the novel microstrip line with periodically perforated ground metal, a miniaturized 17 ${\Omega}$ power divider was fabricated. The line width of the power divider was 20 ${\mu}m$, and the size of it was 0.110 $mm^2$, which is 21 % of conventional one. The power divider exhibited good RF performances from 10 to 20 GHz.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.06a
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• pp.417-422
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• 2005

Using the novel microstripline with periodically perforated ground metal, a miniaturized 1/4 ${\lambda}$ transformer was fabricated. The line width of the 1/4 ${\lambda}$ transformer was 20${\mu}m$ and the size of it was 0.0085$mm^2$, which is 1.2% of conventional one. The 1/4 ${\lambda}$ transformer exhibited good RF performances from 10 to 25GHz.

• Journal of Electrical Engineering and Technology
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• v.5 no.3
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• pp.497-502
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• 2010

In this paper, the O-mode ultrashort-pulse reflectometry (USPR) millimeter-wave signals that propagate into the plasma and cover a frequency bandwidth of 33-158 GHz are examined numerically using MATLAB. Two important processes are involved in the computation: the propagation of the USPR impulse signal through a waveguide and the frequency up-conversion using millimeter-wave mixers. These mixers are limited to intermediate frequency signals that are less than 500 mV; thus, it is necessary to disperse the impulse signal into a chirped waveform using the waveguide. The stationary phase method is utilized to derive a closed-form formula for a chirped waveform under the assumption that the USPR impulse is Gaussian. In the process of frequency up-conversion, the chirped waveform is mixed with the mixer LO signal, and the lower frequency components of the RF signal are removed using high pass filters.