• Publications of The Korean Astronomical Society
• /
• v.29 no.3
• /
• pp.53-58
• /
• 2014

We improved the antenna efficiency of the Taeduk Radio Astronomy Observatory (TRAO) 13.7-m radio telescope by adjusting the antenna panels based on digital photogrammetric measurements. First of all, we measured the surface accuracy of the main reflector of this antenna at three elevation angles of $35^{\circ}$, $45^{\circ}$, and $60^{\circ}$. We performed a total of four sets of the photogrammetric measurements and panel adjustments. When adjusting the panels, we positioned the antenna to the zenith and applied the measured data sets at the elevation of $45^{\circ}$. We found that the antenna surface accuracy has been improved by a factor of ~ 3 times after the final adjustment in comparison with the value before the adjustments. And we also found that the antenna surface accuracy tended to be slightly better at the elevation angles of $35^{\circ}$ and $60^{\circ}$ than that at the elevation angle of $45^{\circ}$. After the final panel adjustment, the aperture and beam efficiencies of the telescope have has been improved from 35% to 44%, and from 41% to 51%, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.28 no.8
• /
• pp.653-660
• /
• 2017

In this paper, the author analyzes direction finding accuracy based on phase comparisons to estimate elevation and azimuth angles of arrival signals. This paper considers the uniform array configurations using four and three elements. In that direction finding structures, I present the analytic expressions for estimated elevation and azimuth angles and then analyze the direction finding errors. And one presents the design guideline of direction finding system in comparison with aspects of accuracy, structure, the number of channels in that structures. The analysis result is similar with simulation one and has difference within $1.2^{\circ}RMS$. From the proposed analysis results, one knows that when SNR is 20 dB and the baseline is half of wavelength, the estimated elevation accuracy of the uniform array using four elements is 1.15 times better than the one of the uniform array using three elements and the estimated azimuth accuracy is same each other. In addition, one knows coning error is eliminated in 2-D direction finding structure.

• Journal of the Korean GEO-environmental Society
• /
• v.24 no.2
• /
• pp.5-12
• /
• 2023

In this study, the amount of heaving soil and the heave characteristics of the heaving soil generated at the actual site were quantitatively analyzed through DCM laboratory test construction. By reproducing a series of construction processes of the DCM method in a large-scale soil tank close to the actual site, the amount of heaving soil was predicted and the elevation characteristics such as elevation, diffusion range, diffusion angle and amount of elevation of the heaving soil were evaluated. As a result of the laboratory test construction, the actual elevation in terms of similarity within the DCM improvement section is 0~8.18m, and an average of 3.50m is observed. The actual diffusion range of the heaving soil converted to the similarity ratio is distributed from 28.0 to 38.0m on the left and right sides of the improvement section. The total amount of heaving soil calculated by the SUFFER program based on the results of the laboratory test construction is 19,901m³. Compared with the injected slurry amount of 16,992m³, the amount of heave compared to the injected amount is analyzed as 85.4%. The diffusion angle of DCM heaving soil, which analyzed the results of DCM laboratory test construction with the SUFFER program, is measured to be 30.0~38.0° at a depth of 50.0m, and is evaluated as an average of 34.0°. On the other hand, based on the DCM laboratory test construction and the analysis results using the program performed in this study, the amount of heaving soil at the DCM depths of 40.0m and 60.0m is predicted.

• 제어로봇시스템학회:학술대회논문집
• /
• 1989.10a
• /
• pp.99-104
• /
• 1989

A practical filter is suggested for ground-Dasea missile tracking in a capture guidance mode, utilizing angle-only measurements from a passive sensor and its performance is evaluated by a realistic system simulation study. Also suggested is a missile acceleration model that provides inputs to the filter. The suggested filter has a decoupled structure of independent azimuth and elevation channels with efficiency in commutation time and memory requirements.

• Proceedings of the Korean Society of Marine Engineers Conference
• /
• 2005.06a
• /
• pp.257-261
• /
• 2005

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 WAVENET control technique to control efficiently its elevation angle and azimuth one. Wavelet neural network(WAVENET) can construct systematically initial neural network as applying wavelet theory to feedforward network. It is proved through computer simulation that WAVENET has more excellent approximation capability than existing neural network. The simulation results using MATLAB are introduced.

• Proceedings of the IEEK Conference
• /
• 2002.06a
• /
• pp.163-166
• /
• 2002

Recently, two kinds of the digital satellite receiver for radio and television have been developed as the global receiving system. The frequency bands of the satellite radio system are ranging from 1, 400MHz to 2, 600MHz, while the satellite television system are ranging from 11, 000MHz to 13, 000MHz New anti-discern antennas have been developed so that satisfies the Omni-characteristics in the horizontal directivity and approximately 45$^{\circ}$'elevation angle in the vertical directivity. These results were similar to the discern antenna except the anti-vertical directivity.

• 제어로봇시스템학회:학술대회논문집
• /
• 2004.08a
• /
• pp.699-703
• /
• 2004

The autopilot system targets decreasing labor, working environment, service safety security and elevation of service efficiency. Ultimate purpose is minimizing number of crew for guarantee economical efficiency of shipping service. Recently, being achieving research about Course Keeping Control, Track Keeping Control, Roll-Rudder Stabilization, Dynamic ship Positioning and Automatic Mooring Control etc. which compensate nonlinear characteristic using optimizing control technique. And application research is progressing using real ship on actual field. Relation of Rudder angle which adjusted by Steering Machine and ship-heading angle are non-linear. And, Load Condition of ship acts as non-linear element that influence to Parameter of ship. Also, because the speed of a current and direction of waves, velocity and quantity of wind etc. that id disturbance act in non-linear form, become factor who make service of shipping painfully. Therefore, service system of shipping requires robust control algorithm that can overcome nonlinearity. In this paper, Using GA algorithm,design autopilot system of ship that could overcome the non-linear factor of ship and disturbance and examined result through simulation.

• 제어로봇시스템학회:학술대회논문집
• /
• 2001.10a
• /
• pp.158.5-158
• /
• 2001

Monopulse active homing radar requires velocity and angle information of target to track fast moving target. Target velocity can be estimated by measuring the frequency shift between transmitted and received frequencies. Angle information is obtained by measuring boresight error. Measurement of doppler frequency component in received signal is done through FFT analysis and interpolation algorithm for fine tuning. Boresight errors in azimuth and elevation axes are proportional to the power of each difference channel relative to sum channel. The target signal power in difference channel is estimated more precisely by measuring the power of FFT result cell of maximum ...

• Korean Journal of Geomatics
• /
• v.1 no.1
• /
• pp.21-26
• /
• 2001

Total Station (TS) is currently widespread and used in many fields of surveying projects. However, its application functions are not perfectly understood and so insufficiently used. One of them is indirect leveling method using TS. Because we can reach a considerable accuracy level with this method, it is gradually expanding for public surveying works such as construction of roads, airports and harbors. This paper gives results of an experiment to increase accuracy of indirect leveling by TS without direct leveling, which is more comfortable and quick to determine elevation.

• International Journal of Contents
• /
• v.1 no.2
• /
• pp.35-38
• /
• 2005

This paper describes a design of simple and precision direction finder that can be adapted to shipboard or mobile vehicles used for Electronic support measure, ELINT and radio signal monitoring systems. The direction finding technology has improved with monolithic integrated circuit, linear array antennas, and interferometer. Interferometer uses the phase-comparison principle and has a good direction finding accuracy but it has an ambiguity problem. We suggest a simple ambiguity solver using phase-comparison technology with amplitude-comparison principle. The direction finding device that has been designed by the suggested method has 0.7 degree RMS error in azimuth angle and 0.6 degree RMS error in elevation angle in 0.5 - 2.0 GHz.