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전계석 光云大學校 1979 論文集 Vol.8 No.-
A simple equivalent circuit of a loop-coupled varactor-tuned Gunn Oscillator is presented. This circuit is used to predict Oscillation frequeay, Tuning characteristics, and mode-switching frequency. Experimentally observed mode-swthing was occurred at 19.2mm of the moving short plunger. And tuning range was 100 MHZ. These were compared with theoretically calculated results.
전계석,고대식 慶熙大學校 大學院 1988 高凰論集 Vol.4 No.-
In this paper, penetration depth of the scanning acoustic microscope (SAM) system has been analyzed. Penetration depth of SAM system depends on the elastic parameters of the material, the signal-to-noise ratio, and the operation frequency of the SAM system. In experiment, it has been shown that penetration depth of SAM system can be increased by the proper selection of the opening angle of the acoustic lens and defocus length.
초음파현미경을 이용한 micro-electronic소자의 결함 검출
田啓石 慶熙大學校 1990 論文集 Vol.19 No.-
In this paper, ultrasonic microscope system has been constructed with a immersion focused transducer and the technique to examine micro-electronic device has been analyzed. The system has been designed at the center frequency of 50 MHz. It has been shown that the resolution of system has been in the range of one wavelength and the penetration depth determined by transmission coefficient and a type of acoustic lens. The propagation charateristic of ultrasonic wave visualizing the interior of micro-electronic devices has been discussed and the experiment made in the various samlmpe(PCB, IC, power TR, a ceramic material). In experimental results, it has been shown that a small aperture type microscope has more advantages than a large aperture type in examining thick samples, and also it has been powerful tool in examing the multi-layer media and the mirco-electronic devices.
田啓石,丁寬秀,金容平 慶熙大學校 1980 論文集 Vol.10 No.-
In X-band, a edge-guided(EG) mode microstrip isolator is designed in which nonreciprocal attenuation is due to the ferromagnetic resonance absorption caused by a strong d-e magnetic field applied locally at the shorted edge of a ferrite microstrip. From modal analysis. the dominant EG mode has been shown to propagate alone the microstrip with one edge shorted to the ground plane. Dispersion relations and rf electric field distributions have been calculated numerically. And the upper limit and the cutoff frequency of band width have been discussed with several design parameters. A practical EG-mode microstrip isolator based on these results has been successfully designed, which has more than 25dB isolation.
탄성표면파 소자를 이용한 대역통과 여파기의 설계에 관한 연구
전계석,황금찬,김봉열 대한전기학회 1982 전기의 세계 Vol.31 No.2
In this paper, surface acoustic wave (SAW) bandpass filter is designed using the Fourier series approach and the I$_{0}$-shin window function. And also we studied a method to realize SAW filter using the apodized ID transducer which was fabricated with aluminum metallization of about 1500 A over .deg. thickness on Y-cut Z-propagating LiNbO$_{3}$, crystal by photolithographic technique (lift-off method). Experimental results on SAW bandpass filter responses show good agreements with the theoretical characteristics.s.
田啓石 慶熙大學校 1982 論文集 Vol.11 No.-
In this paper, the analysis of leaky-wave antenna is studied using a microwave network approach which is based on a transverse resonance method. And then, the network resonance equations, which must be solved for the complex propagation constant of leaky waves, can be conveniently treated by a perturbation technique. In experiment a power-ratio method is used for the attenuation constant measurements of leaky waves, and a interferometer method for its guide wavelength measurements. Experimental results on leaky-wave antenna show good agreements with the theoretical characteristics.