• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.363-365
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• 1994

In switched reluctance motors(SRM), shaft position sensing is essential in order to synchronize the excitation pulse of a pertinent phase to the rotor position. This paper describes the operation of SRM drive using a simple position sensor of low cost. The position sensor is composed of a slotted disk similar to the rotor core shape of a prototype 6/4 SRM and three opto-interrupters disposed at an angle of 30 degrees. The phase current waveforms measured at several rotor speeds in experiment arc compared with those obtained through the computer simulation.

• Journal of the Korean Society of Safety
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• v.27 no.4
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• pp.33-37
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• 2012

This paper describes the characteristics for ground impedance of counterpoise according to position of auxiliary probe and frequency using the fall-of-potential method and the testing techniques to minimize the measuring errors are proposed. The fall-of-potential method is theoretically based on the potential and current measuring principle and the measuring error is primarily caused by the position of auxiliary probes. In order to analyze the effects of ground impedance due to the distance of the current probe and frequency, ground impedances were measured in case that the distance of current probe was located from 10[m] to 100[m] and the measuring frequency was ranged in 55 [Hz], 128[Hz], 342[Hz], and 513[Hz]. The results could be help to determine the position of auxiliary probe when the ground impedance was measured at grounding system.

• Journal of Electrical Engineering and Technology
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• v.12 no.4
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• pp.1449-1455
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• 2017

The vector control technique using low-resolution Hall-effect sensors has been widely used especially in consumer electronics. Due to electrical and/or mechanical unevenness related to binary-type Hall sensors, the calculated or estimated position information has discontinuities so called bumps, which causes the deterioration of vector control performance. In order to obtain a linearly changing position signal from low-precision Hall-effect sensors, this paper proposes a simple bumps in position signal removal algorithm that consists of a first-order observer with low-pass filtering scheme. The proposed algorithm has the feature of no needs for system parameters and additional estimation processes. The validity of the proposed method is verified through simulation and experimental results.

• Journal of Korean Neurosurgical Society
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• v.44 no.6
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• pp.392-395
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• 2008

Lateral femoral cutaneous neuropathy occurring during spinal surgery is frequently related to iliac bone graft harvesting, but meralgia paresthetica (MP) can result from the patient being in the prone position. Prone position-related MP is not an uncommon complication after posterior spine surgery but there are only few reports in the literature on this subject. It is usually overlooked because of its mild symptoms and self-limiting course, or patients and physicians may misunderstand the persistence of lower extremity symptoms in the early postoperative period to be a reflection of poor surgical outcome. The authors report a case of prone position-related MP after posterior lumbar interbody fusion at the L3-4 and reviewed the literature with discussion on the incidence, pathogenesis, and possible risk factors related to this entity.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.11
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• pp.930-935
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• 2005

In this paper, position tracking control of an autonomous helicopter is presented. Combining an LQR method and a proportional control forms a simple PD control. Since LQR control gains are set for the velocity control of the helicopter, a position tracking error occurs. To minimize a position tracking error, neural network is introduced. Specially, in the frame of the reference compensation technique for teaming neural network compensator, a position tracking error of an autonomous helicopter can be compensated by neural network installed in the remotely located ground station. Considering time delay between an auto-helicopter and the ground station, simulation studies have been conducted. Simulation results show that the LQR with neural network performs better than that of LQR itself.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.11
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• pp.1034-1039
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• 2012

In this paper, a structure of precise positioning based on satellite navigation system is proposed. The proposed system is consisted with three parts, range domain filter, navigation filter and position domain filter. The range domain filter generates carrier phase-smoothed-Doppler and Doppler-smoothed-code measurements. And the navigation filter calculates position and velocity using double-differenced code/carrier phase/Doppler measurements. Finally, position domain filter smooth position error, and it means enhancement of positioning performance. The proposed positioning method is evaluated by trajectory analysis using precise map date. As a result, the position error occurred by multipath or cycle slip was reduced and the calculated trajectory was in true lane.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.4
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• pp.290-298
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• 2013

Geomagnetic is refracted by building's wall and pillar. Therefore refracted geomagnetic is able to be used as feature point. In a specific space, a mobile device that is equipped with magnetic sensor array measures 3-axis magnetic field for each point. Magnetic field map is acquired by collecting the every sample point in the magnetic field. The measured magnetic field must be calibrated, because each magnetic sensor has a distortion. For this reason, sensor distortion model and sensor calibration method are proposed in this paper. Magnetic field that is measured by mobile device matches magnetic field map. Result of the matching is used for position estimation. This paper implements hardware system for position estimation method using magnetic field map.

• Transactions of The Korea Fluid Power Systems Society
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• v.8 no.2
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• pp.29-35
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• 2011

These days the injection molding work and press work are in the trend of needing the precision control of position and pressure in a high speed. On the other hand the digital computer technology is developing rapidly. And recently the digital servo controller using micro controller become to be used more broadly, because of the merit of digital communication. In this study the sequential control of hydraulic system switching from position to pressure and to position is tried using the HACD(Hydraulic Axis Controller Digital for electrohydraulic drives) which is manufactured by BoschRexroth. Through this, the possibility of the precision sequential control using the digital servo controller HACD is examined.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.4
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• pp.195-202
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• 2002

The high performance position controller named 'Unified PID Position Controller'is presented in part 1 of this paper. In part 2, we provide smart gain adjustment methods including the freedom utilizations for rare sensitivity toward the system parameter variation and for increasing the stiffness of the system. Owing to the provided gain tuning strategy, the overall system characteristics can be stabilized without over-shoot phenomena when the system parameter is changed in the rate of from 0.5 to 2∼4. Moreover, for the actual feasibility to the industrial fields, a simple butt effective anti-windup strategy prohibiting the integral component of the PID position controller from saturation is presented too. All of the presented algorithms are verified through the experiment works with commercial linear motor.

• Proceedings of the KIEE Conference
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• 2009.04a
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• pp.166-168
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• 2009

In this paper, we studied fire sensing and position tracing system in fire region. The coordinates of fire position is communicated to fire suppression system immediately. And the fire is suppressed by this system effectively. For the purpose, the fire occurrence region images are extracted with two different CCD surveillance cameras and fire occurrence are sensed, I suggested a method to measure the fire occurrence position. It was able to be sensed early experiment result fire outbreak and, I was able to understand a fire outbreak position coordinate at the moment when a fire occurred and, I confirmed that I could accomplish warning official announcement and fire suppression in an auto.