• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.26 no.7
• /
• pp.656-665
• /
• 2015

In this paper, we improved the clarity and quality of the radar imaging by applying motion compensation for time-frequency transform in B-ISAR imaging. The proposed motion compensation algorithm using UWB radar is verified. B-ISAR algorithm procedure and time-frequency transform for improved motion compensation are provided for theoretical ground. The image was created by a UWB Radar B-ISAR imaging algorithm method. Also, creating a B-ISAR imaging algorithm for motion compensation of time-frequency transformation method was used. The B-ISAR Imaging algorithm is implemented using STFT(Short-Time Fourier Transform), GWT(Gabor Wavelet Transform), and WVD(Wigner-Ville Distribution) approaches. The performance of STFT is compared with the GWT and WVD algorithms. It is found that the WVD image shows more clarity and decreased spread phenomenon than other methods.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.26 no.2
• /
• pp.218-225
• /
• 2015

Inverse synthetic aperture radar(ISAR) is coherent imaging system formed by conducting signal processing of received data which consists of radar cross section(RCS) reflected from maneuvering target. A novel algorithm is proposed to compensate inter-pulse motion(IPM) for the purpose of forming an well-focused ISAR image through signals generated by stepped chirp waveform( SCW). The velocity and acceleration of the target related to IPM are estimated based on particle swarm optimization (PSO) which has been widely used in optimization technique. Furthermore, a modified PSO which enables us to improve the performance of PSO is used to compensate IPM in a very short-time. Simulation results using point scatterer model of a Boeing-737 aircraft validate the performance of the proposed algorithm.

• Journal of the Korean Institute of Telematics and Electronics T
• /
• v.36T no.4
• /
• pp.94-102
• /
• 1999

This paper is related with the compensation of communication channel characteristics using predistorter, and the considered characteristic is the additive noise, phase rotation and frequency selective fading which occurred in communication channel. Predistorter can minimize the effect of obstacle element which occured in channel at receiving side by transmitting the predistortion of signal after modulation, the coefficient of inverse electrical charateristic of communication channel is performed at transmitting side. For this purpose, the predistorter is designed by using Tricepstrum Equalization Algorithm which is adaptive equlizer algorithm, and the receiving side must transmit the probing signal to transmitting side. Using the probing signal, the transmitting side can obtain the inverse characteristic coefficient of communication channel, and this probing signal must be transmitted periodically. We assumed that the channel characteristic do not change during this one period. As a result of computer simulation, we confirmed that the performance of predistorter was fairly good as same as the adaptive equalizer, and this technique have a effectiveness that can be used in the forward channel of mobile communication in order to achieve high speed transmission.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.30 no.7 s.250
• /
• pp.741-749
• /
• 2006

For last couple of decades, uses of TFI-LCDs have been expanded to many FPD(Flat Panel Display) applications including mobile displays, desktop monitors and TVs. Furthermore, there has been growing demand for increasingly larger LCD TVs. In order to meet this demand as well as to improve productivity, LCD manufactures have continued to install larger-generation display fabrication facilities which are capable of producing more panels and larger displays per mother glass(substrate). As the size of mother glass becomes larger, a robot required to handle the glass becomes bigger accordingly, and its end effectors(arms) are extended to match the glass size. With this configuration, a considerable static deflection occurs at the end of the robot arms. In order to stack maximum number of mother glasses on a given footprint, the static deflection should be compensated. This paper presents a novel static deflection compensation algorithm. This algorithm requires neither measurement instrument nor additional vertical axis on the robot. It is realized by robot controller software. The forward and inverse kinematics considering compensation always guarantees a unique solution, so the proposed algorithm can be applied to an arbitrary robot position. The algorithm reduced static deflection by 40% in stationary robot state experiment. It also improved vertical path accuracy up to 60% when the arm was running at its maximum speed. This algorithm has been commercialized and successfully applied to a seventh-generation LCD glass-handling robot.

• 제어로봇시스템학회:학술대회논문집
• /
• 2003.10a
• /
• pp.150-155
• /
• 2003

We discussed a quantitative structure-activity relationships (QSAR) technique on incomplete data set. We proposed a new solver that used 2 kinds of multi-layer neural networks. One is to compensate the defect data, and another is to evaluate the QSAR. The solver can predict the defects in model QSAR data. By using them, we get very high precision QSAR. It is 5-10 times higher than that of a traditional method. However, in case of anti-cancer Carboquone, the prediction is not so complete. It was about O(3) wrong than the model calculation. The predicted values would have rather large error. It is caused by noisy observations of Carboquone. However, if we used the uncertain predictions, new data are included in QSAR. If not, they were omitted. The effect would not be little. Therefore, we evaluated the QSAR. The results are contrary to the expectation, are not so wrong. We believe that the wrong effect is suppressed by including information of new data.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.23 no.2
• /
• pp.97-105
• /
• 2020

In order to set up radar cross section(RCS) reduction factors for a target, the scattering point position of the target should be identified through inverse synthetic aperture radar(ISAR) image analysis. For this purpose, ISAR image focusing is important. Maritime ship is non-linear maneuvering in the sea, however, which blur the ISAR image. To solve this problem, translational and rotational motion compensation are essential to form focused ISAR image. In this paper, hourglass and ISAR image analysis are performed on the collected data in the sea instead of using the prediction software tool, which takes much time and cost to make computer-aided design(CAD) model of the ship.

• International Journal of Aeronautical and Space Sciences
• /
• v.18 no.1
• /
• pp.129-137
• /
• 2017

When the micro-Doppler (MD) image of a ballistic missile is derived, the translational motion compensation (TMC) method is usually applied to the inverse synthetic aperture radar (ISAR) image, but yields poor results because of the micro-motion of the ballistic missile. This paper proposes an efficient TMC method to obtain a focused MD image of a ballistic missile engaged in complicated micro-motion. During range alignment, range profiles (RPs) are coarsely aligned by using the 1D entropy cost function of RPs as a mark, then the coarsely-aligned RPs are fine-aligned by using the minimum 2D entropy of the MD image. During phase adjustment, the gradient of the phase error is appropriately weighted and added to the previous phase error to further fine-tune the aligned RPs. In simulations using the point scatterer model and the measured data from the real missile model, the proposed method provided better image focus than the existing method.

• Safety and Health at Work
• /
• v.3 no.4
• /
• pp.294-297
• /
• 2012

Previous studies on the vast increase in suicide mortality in Southeast Asia have indicated that suicide rates increase in parallel with a rise in unemployment or during periods of economic recession. This paper examines the effects of economic recession on suicidal rates amongst agriculture, fisheries, and forestry workers in Korea. Monthly time-series gross domestic product (GDP) data were linked with suicidal rates gathered from the cause of death records between1993-2008. Data were analyzed using generalized additive models to analyze trends, while a polynomial lag model was used to assess the unconstrained time lag effects of changes in GDP on suicidal rate. We found that there were significant inverse correlations between changes in GDP and suicide for a time lag of one to four months after the occurrence of economic event. Furthermore, it was evident that the overall relative risks of suicide were high enough to bring about social concern.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.14 no.11
• /
• pp.1156-1160
• /
• 2003

Many time-frequency analysis techniques have been used for motion compensated ISAR(Inverse Synthetic Aperture Radar) imaging. In this work, a novel time-frequency(T-F) analysis called evolutionary adaptive wavelet transform (EAWT) and evolutionary adaptive joint time-frequency(EAJTF) procedure are used for the motion compensated ISAR image. To show the validity of our algorism, we use simulated MIG-25 and Boeing 727(B-727) ISAR data. From the constructed ISAR image using EAWT and EAJTF, we show that our algorithm can obtain a clear motion compensated ISAR image such as other time-frequency analysis techniques.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.25 no.9
• /
• pp.930-937
• /
• 2014

Inverse synthetic aperture radar (ISAR) images can be generated by radar which radiates the electromagnetic wave to a target and receives signal reflected from the target. ISAR images can be widely used to target detection and recognition. This paper proposed a method of generation of high resolution ISAR images by synthesizing frequency spectrums of each stepped chirp waveform in one burst and sub-sampling in frequency domain. This process is performed over entire bursts during coherent processing interval. Conventional ISAR image generation method using stepped frequency waveform has a severe problem of short unambiguous range, loading to ghost phenomenon. However, this problem can be resolved by the proposed method. In simulations, we generate high resolution ISAR image of the moving target which is Boeing-737 aircraft model composed of several ideal point scatterers.