• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.121.3-121
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• 2001

The movement of a ship is important for DBS(Direct Broadcasting Satellite) Receiving Antenna control algorithm design on shipboard. Especially, turning of ship is essential factor to affect the angle change of azimuth and elevation. Therefore, to track the satellite stably, we need the tracking method considering turning rate of ship. In this paper, we propose an effective satellite tracking algorithm for DBS receiving antenna on shipboard. In the proposed method, when a ship is turned, it selects one of the Multi tracking modes - Normal mode, Low speed mode, Middle speed mode and High speed mode - according as turning rate to be calculated by using Gyro sensor.

• ETRI Journal
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• v.18 no.4
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• pp.287-299
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• 1997

Integrated-optic polarization controlling devices such as polarizers, polarization splitters, and polarization converters, are proposed and demonstrated in nonlinear optic polymers. Poling-induced birefringence in electro-optic polymers is exploited to fabricate the devices. The polymeric waveguide polarizers show low excess losses, and extinction ratios of 20.7 dB and 17.1 dB for TM-pass and TE-pass polarizers, respectively. The polymeric waveguide polarization splitters exhibit TE-TM mode splittings with crosstalk of 14.2 dB and 10.1 dB for TM and TE mode splittings, respectively. The polymeric waveguide polarization converters show successful TE/TM polarization mode conversion with conversion efficiencies of higher than 30 dB. The device employs poling-induced waveguides which have slowly rotating azimuth angle of optic axis along the light propagation direction. The novel polarization converter is insensitive to wavelength and easier to fabricate than the other polarization converters containing periodic structures.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.683-686
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• 2002

The hydrodynamic instability of the three-dimensional boundary-layer over a rotating disk has been numerically investigated for three cases flows using linear stability theory (i.e. Rossby number, Ro = -1, 0, and 1). Detailed numerical values of the disturbance wave number, wave frequency, azimuth angle, radius (Reynolds number, Re) and other characteristics have been calculated for $K{\acute{a}}rm{\acute{a}}n$, Ekman and $B{\"{o}}ewadt$ boundary-layer flows. Neutral curves for these flows are presented. Presented are the neutral stability results concerning the two instability modes (Type I and Type II) by using a two-point boundary value problem code COLUEW that was based upon the adaptive orthogonal collocation method using B-spline. The prediction from the present results on both instability modes among the three cases agrees with the previously known numerical and experimental data well.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.669-673
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• 2008

Based on the averaged Korean head shapes that are the results of digital Korean project by KISTI and Catholic university, experimental apparatus of head dummies of Korean male and female are developed in order to measure head-related transfer functions (HRTF) by using a reverse engineering and rapid prototyping techniques. For the Korean dummies, HRTFs are measured using the substitution method over 12 kHz frequency bands. At every azimuth angle $15^{\circ}$ HRTFs are measured for elevation angles $-30^{\circ}$, $0^{\circ}$, and $30^{\circ}$. The measured HRTFs are compared with those of KEMAR (Knowles Electronic Manikin for Acoustic Research) dummy head, which shows a little different frequency characteristic beyond 2 kHz frequency band.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.86-88
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• 1997

The helicopter system is non-linear and complex. Futhermore, because of absence of an accurate mathematical model, it is difficult accurately to control its attitude therefore, we propose a fuzzy control technique to control efficiently its elevation angle and azimuth one. This controller is on the basis of expert's knowledges and his experiences. The simulation results using MATLAB are introduced.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.4
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• pp.675-684
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• 2004

The Helicopter system has a non-linearity and complexity. Futhermore, because of absence of its correct mathematical model. it is difficult to control accurately its attitudes for elevation angle and azimuth one. Therefore, we proposed a GA-PID control technique to control these angles efficiently. The proposed GA-PID controller can systematically generate optimal PID parameters by applying GA theory to a helicopter attitude control system. Through the computer simulation, the GA-PID technique shows better attitude control characteristic than traditional PID control technique.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.905-908
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• 1988

In recent, Kalman filter technique has been much used as one of technique for tracking of the moving target. But some problem are still remained to be resolved. For example, when Kalman filter technique is applied to nonlinear system, the technique is nonoptimal estimator. Therefore, extended Kalman filter is proposed to reduce modeling error for nonlinear system. In this study, an extended Kalman filter in Cartesian coordinates is described for moving target, when the radar sensor measures range, azimuth and elevation angle in polar coordinates. And an approximate gain computation algorithm is proposed. In this approach, Kalman gains are computed for three uncoupled filter and multiplied by a Jacobian transformation determined from the measured target position and orientation.

• Proceedings of the KIEE Conference
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• 1998.07b
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• pp.497-499
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• 1998

the satellite tracking problem of Antenna with two axis of elevation angle and azimuth one is described in this paper. The proposed control procedures for stabilization of nonlinear pedestal unit are consists of a off-line modeling identified by neural network and a on-line neural network controller combined with a reference model using the least square method. the simulation results are introduced and compared to a conventional PID controller.

• Proceedings of the KIEE Conference
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• 1998.07b
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• pp.534-536
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• 1998

The helicopter system is non-linear and complex. Futhermore, because of absence of accurate mathematical model, it is difficult accurately to control its attitude. therefore, we propose a PID Neural Networks control technique to control efficiently its elevation angle and azimuth one. The coefficients of PID controller are automatically adjusted by the back-propagation algorithm of a neural network. The simulation results using MATLAB are introduced.

• 한국지구물리탐사학회:학술대회논문집
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• 2007.06a
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• pp.81-86
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• 2007

Spectral features of the seismic wave propagation from Odaesan Earthquake were evaluated based on the commonly treated random error between the observed data and the prediction values by the stochastic point-source ground-motion spectral model regarding the source, path and site effects. Radiation pattern of the error according to azimuth angle was found to be similar to the theoretical estimate. It was also observed that the spatial distribution of the errors was correlated with the geological map and the Q0 map which are indicatives of seismic boundaries.