• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.5
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• pp.808-811
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• 2022

In this paper, a wide-range microphone system for lectures using dual 3D sensors is proposed. A previous work using a single sensor had lowering the detecting threshold to support wide-area. However it was found that an error occurred when lecturer wears clothes with low reflectivity or has small body size. When multiple sensors are used to expand the coverage it could be cause various problems. Each sensor could show different distance to the same target. We derive the rotation angle and and compensate for lecturing microphone system using sensors on the line. The proposed method shows a little improvement in performance by about 1dB compared to the previous works but the performance is uniform in all areas regardless of reflectivity.

• International Journal of Aeronautical and Space Sciences
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• v.7 no.1
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• pp.106-117
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• 2006

The active vibration control of composite shell structure has been performed with the optimized sensor/actuator system. For the design of sensor/actuator system, a method based on finite element technique is developed. The nine-node Mindlin shell element has been used for modeling the integrated system of laminated composite shell with PVDF sensor/actuator. The distributed selective modal sensor/actuator system is established to prevent the effect of spillover. Electrode patterns and lamination angles of sensor/actuator are optimized using genetic algorithm. Continuous electrode patterns are discretized according to finite element mesh, and orientation angle is encoded into discrete values using binary string. Sensor is designed to minimize the observation spillover, and actuator is designed to minimize the system energy of the control modes under a given initial condition. Modal sensor/actuator for the first and the second mode vibration control of singly curved cantilevered composite shell structure are designed with the method developed on the finite element method and optimization. For verification, the experimental test of the active vibration control is performed for the composite shell structure. Discrete LQG method is used as a control law.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.721-724
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• 2014

Ultrasonic sensor is used widely for many applications because low cost, simple structure, and low restriction. There are many difficulties to recognize an object by use an ultrasonic sensor, because of low resolution, poor direction, and measurement error. To improve the these problem, we use the various kinds of sensor arrangement methods, large amount of sensor, and change the arrangement pattern of sensor. In this paper, to obtain the most basic parameters for pattern recognition such as distance, dimension of the object, an angle of the object, we get the improved results by use the intelligent calculation algorithm based on Neuro-Fuzzy. This method use the multifarious output voltage of ultrasonic sensor by simple electronic circuit.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.2 s.245
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• pp.117-125
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• 2006

In the present study the unsteady forces acting on the pitching foils such as a flat plate, NACA0010, NACA0020, NACA65-0910 and BTE have been measured by using a six-axis sensor in a circulating water tunnel at a low Reynolds number region. The unsteady characteristics of the dynamic drag and lift have been compared to the quasi-steady ones which are measured under the stationary condition. The pitching motion is available for keeping the lift higher after the separation occurs. Especially, the characteristics of the dynamic lift are quite different from the quasi-steady one at high pitching frequency regions. As the pitching frequency deceases, the amplitude of the dynamic lift becomes closer to the quasi-steady one. However, the phase remains different between the steady and unsteady conditions even at low pitching frequencies. On the other hand, the dynamic drag is governed strongly by the angle of attack.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.9
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• pp.407-413
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• 2005

The optical current transformer was developed for 170 kV GIS using optical fiber. The sensor optimized on the optical CT was wound 3 turns and twisted 4 times per a turn at the pipe with a diameter of 130 m. To optimize the optical CT, the output signal was measured according to the setting angle of polarizer and analyzer, The asymmetry and distortion of the output signals were improved when the parallel polarized light was incident to the fiber sensor and under the angle of analyzer was $45^{o}$. The measurement error for the linearity was only $\pm{0.42}\;\%$ to 1,000 A in the case of reflection type.

• Journal of Sensor Science and Technology
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• v.27 no.3
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• pp.165-169
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• 2018

A single-axis Cubli frame realized simply with an IMU sensor and DC motor is presented herein. To maintain the balance on the Cubli frame, an LQR controller based on a Lagrangian derivation of the dynamics was designed, which utilized the state variables of the frame angle and its angular acceleration, as well as the wheel angle and its angular acceleration. The designed LQR controller showed a settling time balancing capability of approximately two seconds and 40% of the maximum overshoot in Matlab/Simulink simulations. Our experimental results of the fabricated Cubli frame matched with the simulation results. It maintained balancing at the reference position even though an initial offset as well as external disturbance during the balancing was applied.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.1105-1109
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• 1995

A CCD-camera, which is structured with vision system, was used to realize automatic seam-tracking system and 3-D information which is needed to generate torch path, was obtained by using laser-slip beam. To extract laser strip and obtain welding-specific point, Adaptive Hough-transformation was used. Although the basic Hough transformation takes too much time to process image on line, it has a tendency to be robust to the noises as like spatter. For that reson, it was complemented with Adaptive Hough transformation to have an on-line processing ability for scanning a welding-specific point. the dead zone,where the sensing of weld line is impossible, is eliminated by rotating the camera with its rotating axis centered at welding torch. The camera angle is controlled so as to get the minimum image data for the sensing of weld line, hence the image processing time is reduced. The fuzzy controller is adapted to control the camera angle.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.4
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• pp.817-819
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• 2007

The purpose of this work is to develop a measurement system of the pendulum test with minimal restriction of experimental environment and little influence of noise. In this work, we developed a vision system without any line between markers and a camera. The system performance is little influenced by the experimental environment, if light are sufficient to recognize markers. For the validation of the system, we compared knee joint angle trajectories measured by the developed system and by the magnetic sensor system during the nominal pendulum test and the maximum speed voluntary knee joint rotation. The joint angle trajectories of the developed system during both tests matched well with those of the magnetic system. Therefore, we suggest the vision system as an alternative to the previous systems with limited practicality for the pendulum test.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.783-786
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• 1991

Generally, The position of mobile robot moving on the plane is measured by the method of dead reckoning, using the encoder system coupled on a wheel axis. But it is noted that the encoder system cannot check the slip of a wheel, often occurring in tracking of the mobile robot. In this study, using velocity angular velocity sensor with a tuning fork vibration system, the system is developed which can measure the directional angle of positional variables on the mobile robot. By measuring the variations of tracking direction mobile robot equipped with this system, following result is found; In spite of the slip at a wheel when measuring the tracking directional angle, the error occurs in the range of .+-. 1 (degree).

• Journal of Biosystems Engineering
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• v.25 no.1
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• pp.55-62
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• 2000

Autonomous farm operation needs to be developed for safety, labor shortage problem, health etc. In this research, an autonomous tractor for tillage was investigated using machine vision and a fuzzy logic controller(FLC). Tractor heading and offset were determined by image processing and a geomagnetic sensor. The FLC took the tractor heading and offset as inputs and generated the steering angle for tractor guidance as output. A color CCD camera was used fro the image processing . The heading and offset were obtained using Hough transform of the G-value color images. 15 fuzzy rules were used for inferencing the tractor steering angle. The tractor was tested in the file and it was proved that the tillage operation could be done autonomously within 20 cm deviation with the machine vision and the FLC.