• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.10
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• pp.966-980
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• 2011

Radar receiving echo signal provides target information - range, velocity and position by signal magnitude and Doppler shift, which are determined by target reflection characteristics and target maneuver. Target angle error is extracted from the magnitude ratio of difference channel to sum channel. In this paper, we introduce a radar Return Signal Simulation Equipment(RSSE) which is implemented for the purpose of performance analysis and evaluation of phased array multi-function radar(MFR). It generates multi-target environment with jamming signals using MC-DDS (Multi-Channel Direct Digital Synthesis), and has scalability by using the efficient hardware configuration. The performance of the developed RSSE has been evaluated under various test environments. Especially, we proved that required target detection performance is achieved by RSP(Radar Signal Processor) interfaced RSSE configuration.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.5
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• pp.763-770
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• 2017

A radome mounted on the front of an aircraft can cause refraction errors for various reasons that occur during maneuver in seeking and tracking a target. This refraction error means that the microwave seeker is detecting apparent target. An Interactive Multiple Model (IMM) algorithm is applied to estimate radome slope mounted on an aircraft in 3D space. However, even though the parameter of uncertain system model such as radome slope can be estimated, the estimated performance can not be guaranteed when it exceeds the range of the predicted value. In this paper, we propose a method to update the predicted value by using the radome slope as the mode parameter of the IMM algorithm, and confirm the radome slope estimation performance of the proposed method.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.31 no.2
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• pp.159-164
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• 2013

It is well known that a single moving camera video is capable of extracting the 3-dimensional position of an object. With this in mind, current research performed image-based monitoring to establish a floating structure model using a camcorder system. Following this, the present study extracted frame images from digital camcorder video clips and matched the interest points to obtain relative 3D coordinates for both regular and irregular wave conditions. Then, the researchers evaluated the transformation accuracy of the modified SURF-based matching and image-based displacement estimation of the floating structure model in regular wave condition. For the regular wave condition, the wave generator's setting value was 3.0 sec and the cycle of the image-based displacement result was 2.993 sec. Taking into account mechanical error, these values can be considered as very similar. In terms of visual inspection, the researchers observed the shape of a regular wave in the 3-dimensional and 1-dimensional figures through the projection on X Y Z axis. In conclusion, it was possible to calculate the displacement of a floating structure module in near real-time using an average digital camcorder with 30fps video.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.9
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• pp.3161-3167
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• 2010

Hall sensors of BLDC(brushless DC) motor are used to detect a position information for a control mechanism, which implements an algorithm for velocity and position control. Actual azimuth and altitude were measured to evaluate a control precision. The measurement revealed comparatively good accuracy that the measured values were $2.02^{\circ}$ and $1.01^{\circ}$ respectively, and the maximum error falls within $1.86^{\circ}$. The developed monitoring system of photovoltaic generation plants is a LCU(Local Control Unit) based on an integrated monitoring system which supports 1:N method for multiple simultaneous connections, remote control and real-time system state monitoring.

• Journal of Astronomy and Space Sciences
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• v.21 no.3
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• pp.221-232
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• 2004

Gauss method for the initial orbit determination was tested using angle-only data obtained by orbit propagation using TLB and SGP4/SDP4 orbit propagation model.. As the analysis of this simulation, a feasible time span between observation time of satellite resulting the minimum error to the true orbit was found. Initial orbit determination is performed using observational data of GPS 26 and Koreasat 2 from 0.6m telescope of KAO(Korea Astronomy Observatory) and precise orbit determination is also performed using simulated data. The result of precise orbit determination shows that the accuracy of resulting orbit is related to the accuracy of the observations and the number of data.

• Journal of Biosystems Engineering
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• v.31 no.6 s.119
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• pp.489-499
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• 2006

Since the application of chemicals in confined spaces under the canopy of an orchard is hazardous work, it is needed to develop an autonomous guidance system for an orchard sprayer. The autonomous guidance system developed in this research could steer the vehicle by tracking an overhead guidance rail, which was installed on an existing frame structure. The autonomous guidance system consisted of an 80196 kc microprocessor, an inclinometer, two interface circuits of actuators for steering and ground speed control, and a fuzzy control algorithm. In addition, overhead guidance rails for both straight and curved paths were devised, and a trolley was designed to move smoothly along the overhead guidance rails. Evaluation tests showed that the experimental vehicle could travel along the desired path at a ground speed of 30 $\sim$ 50 cm/s with a RMS error of 5 cm and maximum deviation of less than 12 cm. Even when the vehicle started with an initial offset or a deflected heading angle, it could move quickly to track the desired path after traveling 2 $\sim$ 3 m. The vehicle could also complete turns with a curvature of 1 m. However, at a ground speed of 50 cm/s, the vehicle tended to over-steer, resulting in a zigzag motion along the straight path, and tended to turn outward from the projected line of the guidance rail.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.7
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• pp.552-558
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• 2014

In this paper, we propose a side-peak cancellation technique of composite binary offset carrier (CBOC) signals for e-navigation. First, we divide a CBOC sub-carrier into several sub-carrier pulses, and then, observe that CBOC autocorrelation is the sum of multiple sub-correlation functions. Finally, we propose a novel correlation function with no side-peak and a sharp main-peak by combining the sub-correlation functions to improve the positioning accuracy. From numerical results, we confirm that the proposed correlation function with a sharp main-peak provides a better positioning performance than the conventional correlation functions in terms of the tracking error standard deviation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.3C
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• pp.125-132
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• 2005

This paper describes a computer vision system based on active IR illumination for real-time gaze discrimination system. Unlike most of the existing gaze discrimination techniques, which often require assuming a static head to work well and require a cumbersome calibration process for each person, our gaze discrimination system can perform robust and accurate gaze estimation without calibration and under rather significant head movement. This is made possible by a new gaze calibration procedure that identifies the mapping from pupil parameters to screen coordinates using generalized regression neural networks (GRNNs). With GRNNs, the mapping does not have to be an analytical function and head movement is explicitly accounted for by the gaze mapping function. Futhermore, the mapping function can generalize to other individuals not used in the training. To further improve the gaze estimation accuracy, we employ a reclassification scheme that deals with the classes that tend to be misclassified. This leads to a 10% improvement in classification error. The angular gaze accuracy is about 5°horizontally and 8°vertically. The effectiveness of our gaze tracker is demonstrated by experiments that involve gaze-contingent interactive graphic display.

• Tunnel and Underground Space
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• v.26 no.4
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• pp.253-265
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• 2016

In this study, travel time data collection of mine equipments was conducted in an underground mine using a reverse Radio Frequency IDentification (RFID) system. In the reverse RFID system, RFID readers and antennas are mounted on mine equipments, and RFID tags are attached to the underground mine gallery. Indoor experiments were performed to analyze how RFID reader transmission power levels affect tag readable area and tag recognition rates. The results showed that travel time measurement become precise when the reader transmission power was reduced, however tag recognition rates were reduced. The field experiments indicated that setting the reader transmission power to 28 dBm maintained the tag recognition rate while minimizing the tracking location error. In addition, the results revealed that the reverse RFID system can be used successfully in an underground mine to collect the travel time data of haulage trucks.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.3 no.1
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• pp.38-46
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• 2010

This paper describes a computer vision system based on active IR illumination for real-time gaze discrimination system. Unlike most of the existing gaze discrimination techniques, which often require assuming a static head to work well and require a cumbersome calibration process for each person, our gaze discrimination system can perform robust and accurate gaze estimation without calibration and under rather significant head movement. This is made possible by a new gaze calibration procedure that identifies the mapping from pupil parameters to screen coordinates using generalized regression neural networks (GRNNs). With GRNNs, the mapping does not have to be an analytical function and head movement is explicitly accounted for by the gaze mapping function. Furthermore, the mapping function can generalize to other individuals not used in the training. To further improve the gaze estimation accuracy, we employ a reclassification scheme that deals with the classes that tend to be misclassified. This leads to a 10% improvement in classification error. The angular gaze accuracy is about $5^{\circ}$horizontally and $8^{\circ}$vertically. The effectiveness of our gaze tracker is demonstrated by experiments that involve gaze-contingent interactive graphic display.