• Journal of Electrical Engineering and Technology
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• v.9 no.4
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• pp.1309-1314
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• 2014

The measurement of stator core loss for an induction motor at each manufacturing process is carried out in this paper. Iron loss in the stator core of induction motor changes after each manufacturing process due to the mechanical stress, which can cause the deterioration of the magnetic performances. This paper proposes a new iron loss measuring system of the stator core in an induction motor, which can be applied to the case when the distribution of magnetic flux density is not uniform along the magnetic flux path. In the system, the iron loss is calculated based on the induced voltage of the B-search coil and exciting current.

• Journal of Electrical Engineering and Technology
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• v.6 no.5
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• pp.666-670
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• 2011

In this paper, a method for detecting broken rotor bar and stator winding fault in a low voltage squirrel-case induction motor using an air-gap flux variation analysis is proposed to develop a simple and low cost diagnosis technique. To measure the leakage flux in radial direction, a radial flux sensor is designed as a search coil and installed between stator slots. The proposed method is able to identify two kinds of motor faults by calculating load condition of motors and monitoring abnormal signals those are related with motor faults. Experimental results obtained on 7.5kW three-phase squirrel-cage induction motors are discussed to verify the performance of the proposed method.

• IE interfaces
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• v.6 no.2
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• pp.117-131
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• 1993

A job sequencing model is developed and its computer system is tested for processing cold-rolled coils in Tandem Cold Mills(TCM) at the Pohang Iron and Steel Company. Given coils waiting to be processed, this system generates a sequence of jobs satisfying operational constraints for the TCM process. We formulate the problem as a constraint satisfaction problem and employ the backtracking technique combined with looking ahead features in order to generate a feasible solution within a reasonable time. Our system is implemented in C language on 80486-based IBM PC. Some tests based on the real data show that our system is adequate with respect to search time and that it consistantly generates a good feasible solution.

• Proceedings of the KSR Conference
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• 1999.11a
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• pp.360-367
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• 1999

An inverter-driven induction motor is used as the traction motor for a high speed drive system that required safety, reliabillity, performance, compact size owing to the space and weight alloted for attaching to train, etc. particularly it is possible to happen the saturation effects of flux density at constant voltage-frequency region and then increase very higher than the at lowed capacity of no-load current and temperature in any case. therefore the optimum design of core, optimum voltage-frequency ratio, adoption of high grade magnetic core have been developed and researched for preventing these problems. this paper show the saturation effects of traction rotor by measuring the induced voltage of search coil at stator teeth and presents optimum voltage-frequency ratio as well as optimum core design through the comparison with efficiency, power factor, load current and no-load current for korea high speed train.

• Journal of Korea Multimedia Society
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• v.9 no.5
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• pp.585-594
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• 2006

Due to the size limit, the voice coil motor (VCM) is adopted in most of the mobile phone camera to control auto-focus instead of step motor. The optical system using the VCM has the property that the focus values are varying even though the same current is induced. It means that an error of the lens position was taken placed due to the characteristics of the VCM. In this paper, a algorithm was proposed to compensate the lens position error using the step size and the search count of each stage. In the proposed algorithm -7 step middle searching stage is inserted the conventional searching algorithm for the fast auto-focus searching and the final searing step size was set to +1 for the precise focus control, respectively. In the experimental results, the focus values was found more fast in the proposed algorithm than the conventional. And more the image quality by the proposed algorithm was superior to that of the conventional.

• Journal of the Korean Magnetics Society
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• v.26 no.4
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• pp.133-136
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• 2016

In this study, we have constructed a measuring system to investigate tensile stress of tendons, which is employed in bridges, by means of the magnetic non-destructive testing (NDT) method. For the twisted 7-strands tendon, we have used Wiedemann effect. An ac current was applied to the tendon and voltage induced from Search Coil on Tendon (SCT) under applying tensile stress was measured. The measuring system consists of tensile stress applying apparatus up to 2 GPa, and ac current supply to apply current to the tendon directly to magnetize the tendon. We have invested two kinds of tendon which were produced by different companies for testing with constructed measuring system. Voltage induced from SCT was decreased up to 1.5 GPa linearly and two kinds of tendon which were produced by different companies shows similar trends. Thus, Wiedemann effect was also applicable to measure tensile stress of tendon by means of magnetic NDT.

• Journal of Astronomy and Space Sciences
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• v.20 no.1
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• pp.29-42
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• 2003

The KSR-3 magnetometers consist of the fluxgate magnetometer (MAG/AIM) for acquiring the rocket flight attitude information, and the search-coil magnetometer (MAG/SIM) for the observation of the Earth's magnetic fluctuations. The position (latitude, longitude, and height) and flight condition (the transformation angle) of the rocket is measured after the data based on these two magnetometers are compared with IGRF The gap in the vector of magnetic field between the position of the launching point and an impact point is taken into account in data reduction. Angular variation of pitch, yaw, and roll can be researched when the data is applied to the coordinate system of the rocket.

• Journal of Magnetics
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• v.21 no.3
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• pp.330-339
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• 2016

A magnetic field sensing system with a single primary sensor and multiple reference sensors deployed locally and orthogonally, was proposed for downlink signal reception and interference cancelling for Through-the-Earth Communication (TEC). This paper mathematically analyzes a design optimization process for a search coil magnetometer (SCM), and applies that process to minimize the bandwidth of the primary SCM for TEC signal reception and the volume of reference SCMs for multiple distributions. The primary SCM achieves a 3-dB bandwidth of 7 Hz, a sensitivity threshold of 120 fT/${\surd}$Hz, and a volume of $2.32{\times}10^{-4}m^3$. The entire sensing system volume is as small as $10^{-2}m^3$. Experiments with interference from industrial frequency harmonics demonstrated an average of 36 dB and 18 dB improvements in signal-to-interference ratio and signal-to-interference plus noise ratio, respectively, using multichannel recursive-least-squares algorithm. Thus, the proposed sensing system can reduce the interference effectively and allows reliable downlink signal reception.

• Annual Conference on Human and Language Technology
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• 1998.10c
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• pp.177-185
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• 1998

한글의 가로쓰기와 세로쓰기 체계의 상대적 효율성을, 글을 읽을 때 관찰되는 시선 이동을 측정하여 비교하였다. 실험 1에서는 동일한 글을 가로와 세로 방향으로 제시하고, 글을 읽는 동안 시선 운동(머리 운동과 안구 운동의 합)을 공막탐지코일법(scleral search coil method)으로 측정하였다. 가로글 읽기의 경우, 시선도약(saccade)의 크기가 더 컸으며, 동일한 크기의 도약운동을 비교할 때, 세로글 읽기에 비해 상대적으로 도약운동의 속도가 높았다. 평균 고정기간(fixation duration)은 글의 읽기 방향에 따른 유의미한 차이를 보이지 않았다. 시선 도약크기와 도약운동 속도에서의 차이는 가로글을 읽는 속도를 높여 글을 읽는 시선 이동의 효율성이 가로글에서 상대적으로 높았다. 실험 2에서는 팔의 읽기 방향에 따른 시선 이동 변수에서의 차이가 글자극의 독특한 자극 특성에 기인한 것인지 혹은 시각 및 안구 운동 체계에서의 차이를 반영하는 것인지를 결정하고자 하였는데, 의미정보가 없는 점자극을 수평과 수직방향으로 제시하고, 방향에 따른 시선 이동의 차이가 글자극을 사용한 경우와 동일하게 나타나는지를 보았다. 점자극에서도 수평 방향의 시선도 약 운동이 보다 크고 정확한 경향성이 있었다. 이 결과는 사람의 시각 운동 체계가 수평 방향의 시선 이동에 대해 선호성을 보이고 있으며, 이러한 시각 및 안구 운동 체계에서의 차이가 글을 읽는 행동에도 반영되고 있음을 보여준다.

• Journal of IKEEE
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• v.22 no.3
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• pp.532-538
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• 2018

This paper proposes an algorithm for signal processing which is used in pulse induction metal mine detectors. The detection power can be obtained from magnetic variation on the search coil. The calibration data should be made when there is no target because the detection power is difference between with and without a target. And it is also updated periodically because of surrounding various noises. Lastly, we keep a watch on the signal slope to identify exact position and signal power of mine detection.