• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2005.10a
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• pp.69-74
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• 2005

In order to evaluate the safety of navigation at sea and the safety of mooring on berthing, it is necessary that the wave and wind induced ship dynamic motion should be measured in real time domain for the validity of theoretical evaluation method sum as sea-keeping performance and safety of mooring. In this paper, the basic design of sensors is discussed and some system configurations were shown. The developed system mainly consists of 4 kind of sensors sum as three dimensional accelerator, two dimensional tilt sensor, two displacement sensors and azimuth sensor. Using this measuring system(MMS), it can be obtained the 6 degrees of freedom of ship dynamic motions at sea and on berthing sum as rolling, pitching, yawing, swaying, heaving, surging under the certain external forces.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.11 no.1
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• pp.72-84
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• 2008

Since enactment of the Baekdu-Mountain Range protection law in Dec. 31st 2003, great interest arose in recovery of the natural environment in the Baekdu-Mountain Range. Since the Baekdu-Mountain Range has formed boundaries between different regions and it is the mountain that crosses our country from East to West, there are so many roads that penetrate this area. Slopes made by the construction of roads have poor foundation for the growth of vegetation and it takes a long period to restore only with natural restoration force. For this reason, various methods of revegetation to restore the damages are implemented but until now, revegetation of domestic soil cutting slopes are mainly covered by foreign import grasses to stabilize and cover grounds early. As we depended upon foreign import grasses for slopes revegetation, the landscape did not match in harmony with surrounding vegetation and therefore, we could see that these foreign grasses are withered in 2~3 years after the revegetation works and slopes become barren again. However, currently, there are no applicable standards for designs of green hill, desirable revegetation methods for the hill areas, roads and recovery models. Therefore, in this study, we investigated the status of revegetation plants and revegetation methods for the hill areas of the Baekdu-Mountain Range (azimuth, degree of tilt, and tilted places). Based on this, we attempted to find the desirable recovery models for the hill areas of the Baekdu-Mountain Range.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.5
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• pp.359-366
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• 2017

In this paper, aerodynamic data of the Gaori kite was constructed through the wind tunnel experiment taking into consideration all the angles of attack formed during the flight of the Gaori kite. From this aerodynamic data, we made a morphing analysis of the relative length of the front bridle to the rear bridle required to achieve equilibrium flight as the angle of attack of the Gaori kite or the azimuth angle change. As a result, it was found that the relative length of the front bridle to the rear bridle depends entirely on the chord length of the kite, the relative wind speed and changes morphed according to the angle of attack. Using this information data, one can adjust the relative length of the bridle line to suit the kite attitudes and flight environments handling the kites that maintain optimal flight performance.

• Journal of Satellite, Information and Communications
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• v.7 no.1
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• pp.75-81
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• 2012

This study is to design the transmitter and receiver of short range UWB(Ultra Wide Band) imaging radar that is able to display high resolution radar image for front area of a UGV(Unmanned Ground Vehicle). This radar can help a UGV to navigate autonomously as it detects and avoids obstacles through foliage. The transmitter needs two transmitters to improve the azimuth resolution. Multi-channel receivers are required to synthesize radar image. Transmitter consists of high power amplifier, channel selection switch, and waveform generator. Receiver is composed of sixteen channel receivers, receiver channel converter, and frequency down converter, Before manufacturing it, the proposed architecture of transceiver is proved by modeling and simulation using several parameters. Then, it was manufactured by using industrial RF(Radio Frequency) components and all other measured parameters in the specification were satisfied as well.

• Journal of Satellite, Information and Communications
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• v.9 no.2
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• pp.74-79
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• 2014

Conventional ScanSAR mode has been adopted in Envisat or Radarsat and played an important role to acquire wide swath SAR images for environmental surveillance. However, it suffers from the undesirable scalloping effect caused by non-homogeneity of antenna pattern while the image resolution is sacrificed. In recent years, TOPS mode has been suggested and put into use to overcome the disadvantages of the conventional scanning mode. Although TOPS mode is able to produce wide-swath SAR image in a short time interval, it demands highly complicated system design knowledge. In this paper, we present the operation principle of TOPS mode and a full SAR simulation is performed to generate TOPS SAR raw data. Azimuth antenna pattern is modified during TOPS mode operation and it is shown that the undesired scalloping effect is suppressed in the generated SAR image.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.5 no.3
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• pp.101-109
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• 2012

Because the installation problem of parabola antenna that is tilted to 45 degree when this antenna is installed at the area of middle latitude, the study on planar antenna in place of parabola antenna is made rapid progess. Especially, The development of the planar antenna for VSAT is needed depending on the increased Ka-band satellite communications. In this paper, in order to meet with these performances, an array antenna consisting of the vertical polarized waveguide longitudinal slots based on the leaky-wave mode of traveling wave antenna is proposed. Especially, for the lower sidelobe level, the design method of the radiation power distribution control using the different slot widths is proposed. An array antenna consisting of 32 leakywave waveguide antennas is showing 35.16 dBi of gain, 2.5 degree of beamwidth at azimuth, below than -30 dB of sidelobe level, 45.8 degree of beam tilt angle in center frequency 30.2 GHz.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.6
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• pp.89-99
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• 2008

In this paper proposes a novel tacking algorithm regarding the power loss when operating a tracking system for a rapidly changing insolation to improve the power of PV hacking system. The tracking system of sensor method used in a conventional PV power station is unable to exactly track a sun position when lacking in the intensity of radiation and has the problem is malfunction of tracking system by a rapidly changing climatic. The tracking system of program method spends too much energy on the unnecessary operation of tracking system because that is unable to adapt itself to a outside factor of climatic environment. In case of tracking an azimuth and altitude of the sun in realtime, therefore, the actual PV power is less increasing than the power of tracking system fixed a specific position. To reduce the power loss, this pap proposes a novel control algorithm of the tracking system. Also, this paper is analyzed efficiency of traditional solar tracking method and proposed method, prove validity of proposed algorithm through demonstrable study.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.5
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• pp.86-94
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• 2008

In this paper proposed the solar tracking system to use a fuzzy based on PC in of order to increase an output of the PV(Photovoltaic) array. The solar tracking system operated two DC motors driving by signal of photo sensor. The control of dual axes is not an easy task due to nonlinear dynamics and unavailability of the parameters. Recently, artificial intelligent control of the fuzzy control, neural-network and genetic algorithm etc. have been studies. The fuzzy control made a nonlinear dynamics to well perform and had a robust and highly efficient characteristic about a parameter variable as well as a nonlinear characteristic. Hence the fuzzy control was used to perform the tracking system after comparing with error values of setting-up, nonlinear altitude and azimuth. In this paper designed a fuzzy controller for improving output of PV array and evaluated comparison with efficient of conventional PI controller. The data which were obtained by experiment were able to show a validity of the proposed controller.

• Journal of the Korean Institute of Navigation
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• v.7 no.2
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• pp.1-45
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• 1983

This paper concerns the applications of the Kalman filter to navigation and the develment of computer programs of the navigational calculations. Methods to apply the Kalman filter to celestial fix, fix by cross bearing and cocked hat are proposed, and numerical simulations under various noise conditiions are conducted. The accuracy of the optimal positions obtained by the Kalman filter is compared with that of the fixed positiions by radial error method. In the case of celestial fix, an algorithm to estimate the optimal positions by using the linear Kalman filter is presented. The optimal positions by the Kalman filter are compared with the running fixes and with the most probable positions obtained from a single line of position. It is confirmed that the resutls of the proposed method are more accurate than the others. In practical piloting, bearings are generally measured intermittently and the measurement process is nonlinear. It is, therefore, difficult for us to apply the Kalman filter to fix by cross bearing. In order to be used in such an unfavorable case, the extended Kalman filter is revised and the aplicability of the revised extended Kalman filter is checked by numerical simulation under various noise conditions. In a cocked hat, an inside or outside fix is dependent only upon azimuth spread, if the error of each line of position is assumed to be equal both in magnitude and sign. A new technique of selecting a ship's position between an inside fix and an outside fix in a cocked hat by using fix determinant derived from the equation of three lines of position is also presented. The relations among the optimal position by Kalman filter, incentre (or excentre) and random error centtre of the cocked hat are discussed theoretically and the accuracy of the optimal position is compared with that of the others by numerical simulation.

• Korean Journal of Remote Sensing
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• v.21 no.2
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• pp.163-171
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• 2005

I have developed a processor for synthetic aperture radar (SAR) raw data compression using range-doppler algorithm for educational purpose. The program realized a generic SAR focusing algorithm so that it can deal with any SAR system if the specification is known. It can run efficiently on a low-cost computer by selecting minimum size out of a whole dataset, and can produce intermediate images during the process. Especially, the program is designed for educational purpose in such a way that Doppler centroid and azimuth ambiguity can be determined graphically by the user. By distributing the source code and the algorithm to public, I intend to maximize the educational effect on understanding and utilizing SAR data. This paper introduces the principle of SAR focusing algorithm embedded on the eSAR processor and shows an example of data processing using ERS-1 raw data.