• Bulletin of the Korean Chemical Society
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• v.22 no.8
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• pp.807-815
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• 2001

Two-dimensional (2D) correlation method, which generates the synchronous and the asynchronous 2D spectrum by complex cross correlation of the Fourier transformed spectra, is an analysis method for the changes of the sample spectrum induced by vari ous perturbations. In the present work, the 2D electronic correlation spectra have been simulated for the cases where the sample spectrum composed of two gaussian bands changes linearly. When only the band amplitudes of the sample spectrum change, the synchronous spectrum shows strong peaks at the band centers of the sample spectrum, but the asynchronous spectrum does not make peaks. When the sample spectrum shifts without changing intensity and width, the synchronous spectrum shows peaks around the initial and final positions of the band maximum and the asynchronous spectrum shows long peaks spanning the shifting range. The band width change produces the complex 2D correlation spectra. When the sample spectrum shifts with band broadening, the width change by 50% of full width at half maximum (FWHM) does not give so large an effect on the correlation spectrum as the spectral shift by one half of FWHM of the sample spectrum.

• Proceedings of the KIEE Conference
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• 1987.07a
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• pp.26-29
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• 1987

This paper concerns methods for ${\mu}$-wave imaging. The image reconstruction of an object by range-doppler preceding using the X-Band Linear-FM signal is presented from tile simulated data. The high degree of range resolution is achived using large signal band width and cross-range resolution is obtained by doppler processing.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.402-403
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• 2018

70GHz-band high gain array antenna is developed for automotive short range radar sensor. In Short-rangeradar, the gain must be high in order to increase the resolution, and the angle width must be set to secure the field of view(Fov). The proposed antenna operates at 76~81GHz and satisfies angle width $60^{\circ}$, antenna gain 15dB and the input reflection coefficient of less than -10dB within the operating frequency. Wave guide WR-10 was used to measure the antenna and results similar to the simulation results were obtained.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.57.3-58
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• 2017

We report the detailed design of an unprecedented wideband(band7+8) corrugated feed horn in ASTE focal plane array aiming for future ALMA receiver. We have found that such design constraints as return loss, cross-polarization level, beam width and phase curvature can be controlled by optimizing critical corrugation parameters at the throat and flare region of the horn. The success of optimization manifest itself through simulated aperture effciency over 80 % at the entire frequency range. Physical implications of the resulting corrugation parameters are discussed.

• Journal of Integrative Natural Science
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• v.2 no.1
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• pp.41-44
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• 2009

Photonic crystals containing multiple rugate structure are prepared by electrochemical etchings. Typically etched rugate PSi prepared in this study. Etching is carried out in a Teflon cell by using a two-electrode configuration with a Pt mesh counter electrode. They exhibit sharp photonic band gaps in the optical reflectivity spectrum. This reflectivity can be tuned to appear anywhere in the visible to near-infrared spectral range, depending on the programmed etch waveform. We study the method of full width half maxima and reflectivity index control by using amplitude.

• Journal of the Society of Naval Architects of Korea
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• v.52 no.1
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• pp.88-95
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• 2015

For the frequency-domain spectral fatigue analysis, the probability density function of stress range needs to be estimated based on the stress spectrum only, which is a frequency domain representation of the response. The probability distribution of the stress range of the narrow-band spectrum is known to follow the Rayleigh distribution, however the PDF of wide-band spectrum is difficult to define with clarity due to the complicated fluctuation pattern of spectrum. In this paper, efforts have been made to figure out the links between the probability density function of stress range to the structural response of wide-band Gaussian random process. An artificial neural network scheme, known as one of the most powerful system identification methods, was used to identify the multivariate functional relationship between the idealized wide-band spectrums and resulting probability density functions. To achieve this, the spectrums were idealized as a superposition of two triangles with arbitrary location, height and width, targeting to comprise wide-band spectrum, and the probability density functions were represented by the linear combination of equally spaced Gaussian basis functions. To train the network under supervision, varieties of different wide-band spectrums were assumed and the converged probability density function of the stress range was derived using the rainflow counting method and all these data sets were fed into the three layer perceptron model. This nonlinear least square problem was solved using Levenberg-Marquardt algorithm with regularization term included. It was proven that the network trained using the given data set could reproduce the probability density function of arbitrary wide-band spectrum of two triangles with great success.

• Proceedings of the KIEE Conference
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• 1987.11a
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• pp.392-397
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• 1987

This paper concerns a method for micro-wave imaging. The image reconstruction of a perfect conducting cylinder by phase and amplitude measurement using the X-Band multifrequency is presented troll the simulated data. The high degree of range resolution is achieved using large signal band-width and cross-range resolution is obtained by doppler processing. The comparison of image reconstruction between range doppler processing and circular convolution algorithm is also shown.

• Journal of the Korean GEO-environmental Society
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• v.14 no.9
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• pp.39-47
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• 2013

Local deformations in back filling materials of two sands and one glass bead with different particle shapes behind a rigid retaining wall were studied. Two kinds of boundary conditions were compared: active wall translation and active rotation of the wall about its toe. Effect of the speed of active wall translation was also investigated. The digital image correlation method was used to analyze local deformation developments inside the materials. Test results showed that particle shape and density mainly influence the inclination angle and width of the shear band. The general shear band pattern is strongly dependent on the wall movement mode, while it was little influenced by particle shape. Within a limited range of wall speed in this study, shear band became wider and local deformation became larger with increase of wall speed.

• Proceedings of the KIEE Conference
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• 1990.07a
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• pp.525-528
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• 1990

In this paper, a CMOS Operational Transconductance Amplifier (OTA) which is used for high-frequency operation has been designed and simulated by SPICE 2G program. To increase input linear range, the input stage is designed by cross-coupled pair. And the output stage insert buffer stage for the buffing and gain. The band-width of designed OTA is $50{\sim}60$ [MHz].

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.7A
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• pp.1057-1062
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• 2000

Allow me to introduce the development of an FM transmitter. The transmitter uses millmeter waves at the frequency of 60 GHz, and it can produce as much as 20 mW power with the band width of 1 GHz. The great feature of the FM transmitter is that it has been created by the special technique of utilizing the NRD (non radiative dielectric) waveguide. The advantage of adopting the NRD waveguide is that it can significantly reduce transmission loss. We can construct a small-size NRD guide transmitter in a simple way that has superb transmission performance. The NRD guide transmitter is very useful for CATV transmission or transmission over a wide range. In addition, the transmitter has almost the same band width as optical communication, and the data transmission speed of the transmitter is faster than that of optical communication. A transmitter with these merits would be highly appreciated as a way of ultra-highspeed communication network over short distances.