• Journal of the Korea Institute of Military Science and Technology
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• v.22 no.1
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• pp.11-19
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• 2019

The waveguide slotted active phased array radar is characterized in that the beam is tilt in a specific direction when the feeding position of the antenna is not in the center of the antenna. If the beam deflection phenomenon is not properly compensated, error bias is generated in the target information collected by the radar, and the target accuracy is lowered. In this paper, we describe a technique to compensate the error of the target information that is collected in the active phased array radar of the waveguide slot type instead of the center of the antenna.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.8
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• pp.29-39
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• 2015

This paper describes a design and implementation of fuzzy-based algorithm for hand-shake state detection and error compensation in the mobile optical image stabilization(OIS) motion detector. Since the gyro sensor output of the OIS motion detector includes inherent error signals, accurate error correction is required for prompt hand-shake error compensation and stable hand-shake state detection. In this research with a little computation overhead of fuzzy-based algorithm, the hand-shake error compensation could be improved by quickly reducing the angle and phase error for the hand-shake frequencies. Further, stability of the OIS system could be enhanced by the hand-shake states of {Halt, Little vibrate, Big vibrate, Pan/Tilt}, classified by subdividing the hand-shake angle. The performance and stability of the proposed algorithm in OIS motion detector is quantitatively and qualitatively evaluated with the emulated hand-shaking of ${\pm}0.5^{\circ}$, ${\pm}0.8^{\circ}$ vibration and 2~12Hz frequency. In experiments, the average error compensation gain of 3.71dB is achieved with respect to the conventional BACF/DCF algorithm; and the four hand-shake states are detected in a stable manner.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.279-285
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• 1993

This paper presents a precision automatic measuring system for ball screw Pitch. Ball screw is mounted on a precision indexing table, and the ball screw pitch is measured via magnetic scale, where the indexing and measurement are performed by a PC. For precision indexing of ball screw, direct driven motor is coupled to the designed dead and live centers; the performance of the centers are assessed with a precision master sylinder,such as radial motion,tilt motion, and axial motions. An error compensation model is constructed for the measurement system of ball screw pitch, where the error motions of indexing system as well as the scale measurement system are combined to give the measurement error for the ball screw. The developed system proposes an automated precision measurement system for manufacturers and users of ball screw.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.565-569
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• 2002

To improve the driving sensitivity of an optical pickup actuator for high density and high speed drive, we present a new actuator design using multipolar flux-density distribution by magnetic materials and Nd-Fe-B sintered magnets. We expect this actuator to use in 3-axis actuator for tilt compensation as well as conventional 2-axis actuator. The electromagnetic field analysis applying 3-D FEM was performed and several samples were actually tested. From comparing simulated data with experimental results, we verified the accuracy of the simulation and the superiority of the presented method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.358.2-358
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• 2002

To improve the driving sensitivity of an optical pickup actuator for high density and high speed drive, we present a new actuator design using multipolar flux-density distribution by magnetic materials and Nd-Fe-B sintered magnets. We expect this actuator to use in 3-axis actuator fur tilt compensation as well as conventional 2-axis actuator. The electromagnetic field analysis applying 3-D FEM was performed and several samples were actually tested. From comparing simulated data with experimental results, we verified theaccuracy of the simulation and the superiority of the presented method.

• Journal of the Optical Society of Korea
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• v.10 no.1
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• pp.23-27
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• 2006

We are studying the application of an adaptive optics system to upgrade the beam quality of a laser. The adaptive optics (AO) system consists of a bimorph deformable mirror, a Shack-Hartmann sensor and a control system. In most AO applications, the beam aperture is considered to be circular. However, in some cases such as laser beams from unstable resonators, the beam apertures are annulus or a holed-rectangle. In this paper, we investigate how well a bimorph deformable mirror of ${\Phi}120\;mm$ clear aperture can compensate phase distortions for three different beam configurations; 1) ${\Phi}120\;mm$ circular aperture, 2) ${\Phi}100\;mm$ annulus aperture with a ${\Phi}20\;mm$ hole and 3) $70\;mm{\times}70\;mm$ square aperture with a hole of $30\;mm{\times}30\;mm$. This study concludes that the bimorph mirror, which might be considered as a modal controller, can compensate tilt, defocus, coma and astigmatism, and spherical aberration for all three beams.

• Journal of the Korean Solar Energy Society
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• v.29 no.1
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• pp.38-43
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• 2009

In this paper. a prototype of a mobile Sun tracking system is proposed. The proposed system uses 2-axis tilt sensor and 3-axis magnetic sensor to measure the orientation and the posture of the system according to the horizontal system of coordinates, which are used to compensate the slope effects. Then through astronomical calculation using the time and position information obtained by GPS sensor the azimuth and altitude of the Sun from that location is calculated. The position of the Sun is converted to that of the mobile Sun tracking system coordinates and used to control A-axis and C-axis of the system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.479-480
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• 2006

We have studied the viewing angle control of a twist nematic liquid crystal display (TN-LCD). The TN-LCD exhibits a bad image quality along vertical direction, due to characteristics such as low contrast ratio and gray scale inversion. The proposed new TN-LCD has the function of switching between the wide viewing mode and narrow viewing angle mode using two tilted LC layers at both sides of a TN-cell. Tilt angles of the two LC layers, $14^{\circ}$ and $60^{\circ}$ were required in both wide viewing angle and narrow viewing angle modes, respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.8C
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• pp.1175-1183
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• 2004

This paper propose a method to trace a moving object based on the information directly obtained from MPEG-2 compressed video stream without decoding process. In the proposed method, the motion flow is constructed from the motion vectors involved in compressed video and then we calculate the amount of pan, tilt, zoom associated with camera operations using generalized Hough transform. The local object motion can be extracted from the motion flow after the compensation with the parameters related to the global camera motion. The moving object is designated initially by a user via bounding box. After then automatic tracking is performed based on the mean-shift algorithm of the motion flows of the object. The proposed method can improve the computation speed because the information is directly obtained from the MPEG-2 compressed video, but the object boundary is limited by blocks rather than pixels.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.6C
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• pp.593-603
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• 2009

In this paper, we propose a new integrated computer vision system designed to track multiple human beings and extract their silhouette with an active stereo camera. The proposed system consists of three modules: detection, tracking and silhouette extraction. Detection was performed by camera ego-motion compensation and disparity segmentation. For tracking, we present an efficient mean shift based tracking method in which the tracking objects are characterized as disparity weighted color histograms. The silhouette was obtained by two-step segmentation. A trimap is estimated in advance and then this was effectively incorporated into the graph cut framework for fine segmentation. The proposed system was evaluated with respect to ground truth data and it was shown to detect and track multiple people very well and also produce high quality silhouettes. The proposed system can assist in gesture and gait recognition in field of Human-Robot Interaction (HRI).