• Proceedings of the Korean Society of Computer Information Conference
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• 2022.01a
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• pp.403-405
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• 2022

본 논문에서는 4차 산업에서 필요로 하는 스마트 기기의 소형 및 저전력 부품에 사용되는 센싱 플랫폼을 제안하였다. 특히 스마트팩토리의 공장 자동화와 정밀 측정의 핵심 부품인 리니어 모션 가이드(LM Guide)를 고정밀, 고정도로 제어할 수 있는 센싱 시스템을 개발하였다. 이를 위하여 기존의 변위 센서 기법의 한계를 극복할 수 있도록 와전류(Eddy Current) 기법을 이용함으로써 LC 공진기와 전도체를 LM 가이드에 장착할 수 있도록 구현하였다. 또한 미세 인덕턴스 값을 측정할 수 있도록 디지털 신호처리 기술과 컴퓨터/산술 기술을 FPGA를 이용한 HW 시스템을 제작하여 구현함으로써 실험을 진행했다. 본 논문에서 구현한 HW 센싱 시스템을 이용하여 LM 가이드를 동작시킴으로 실시간으로 변위 값을 디스플레이 부로 출력되어 측정이 가능하고, 변위 값의 분해능과 응답속도 면에서 우수함을 확인할 수 있다.

• Journal of the Korean Society for Nondestructive Testing
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• v.35 no.5
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• pp.291-298
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• 2015

An array type probe for monitoring metal tubes is proposed in this paper which utilizes peak value and peak time of a pulsed eddy current(PEC) signal. The probe consists of an array of encircling coils along a tube and the outside of coils is shielded by ferrite to prevent source magnetic fields from directly affecting sensor signals since it is the magnetic fields produced by eddy currents that reflect the condition of metal tubes. The positions of both exciter and sensor coils are consecutively moved automatically so that manual scanning is not necessary. At one position of send-receive coils, peak value and peak time are extracted from a sensor PEC signal and these data are accumulated for all positions to form an array type peak value signal and an array type peak time signal. Numerical simulation was performed using the backward difference method in time and the finite element method for spatial analysis. Simulation results showed that peak value increases and the peak appears earlier as the defect depth or length increases. The proposed array signals are shown to be excellent in reflecting the defect location as well as variations of defect depth and length within the array probe.

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2371-2373
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• 1999

This paper deals with the development, reliability, specification and performances of the ACSR inner corrosion detector system. It is designed to run on ACSR automatically and to inspect the corrosion of the line with on-line continuously. And it comprises a sensor a constant current source, a signal processing unit, a RF transmitter and receiver unit. Also separable encircling coil sensor is proposed in order to detect inner corrosion of the overhead ground wires. In conclusion, this detector can realize the nondestructive detecting of an ACSR inner corrosion.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.6
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• pp.43-50
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• 2000

Design and experiments of a nondestructive testing system with a solenoid eddy current sensor to inspect deterioration of ASCR-OC (ACSR Outdoor Cross-linked Polyethylene Insulated Wires) usually used in HV overhead distribution lines in domestic areas in presented in this paper. Through corrosion mechanisms and deterioration results for ACSR-OC conductors are examined, it is shown that corrosion may lead to the reduction of the effective cross section area of conductors is proposed. The measurement system consisting of a constant current source with a RF frequency, a signal processing unit and a motor driver/ controller is designed and implemented. This instrument has such capabilities as detecting the sensor output and estimating diameter change of the testing conductors, continuously. As a result, it was verified that such corrosion detector system with an eddy current sensor can be shown good effectiveness for estimating the serious faults due to deterioration in overhead distribution lines and giving an early warming before severe aged conductor may lead to fail.

• Journal of the Korean Society for Nondestructive Testing
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• v.36 no.3
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• pp.195-201
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• 2016

Eddy current testing (ECT) is commonly applied for the inspection of automated production lines of metallic products, because it has a high inspection speed and a reasonable price. When ECT is applied for the inspection of a metallic object having an uneven target surface, such as the spline gear of a spline shaft, it is difficult to distinguish between the original signal obtained from the sensor and the signal generated by a defect because of the relatively large surface signals having similar frequency distributions. To facilitate the detection of defect signals from the spline gear, implementation of high-order filters is essential, so that the fault signals can be distinguished from the surrounding noise signals, and simultaneously, the pass-band of the filter can be adjusted according to the status of each production line and the object to be inspected. We will examine the infinite impulse filters (IIR filters) available for implementing an advanced filter for ECT, and attempt to detect the flaw signals through optimization of system design parameters for detecting the signals at the system level.

• Proceedings of the KWS Conference
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• 2005.11a
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• pp.144-146
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• 2005

Dual electromagnetic sensor is used for sensing the weld line. The sensor consists of excitation and two sensing coil wound over the ferro-magnetic core. By using the dual sensor, the effect of noise is minimized. It is based on the generation of eddy currents in the welding plate by passing current through the excitation coil. The sensor can be used to track the butt joints having no gap between them, where a vision based sensor fails to track. Sensor sensitivity depends on the number of coil turns, frequency of excitation, distance of a sensor from the work piece, diameter of core, etc. The whole system consists of a sensor, a signal processing board, a motion controller and a personnel computer (PC). The raw sensor signal is processed using the signal processing board. It consists of amplification, rectification, filtering, averaging, offset adjustment, etc. Based on sensor data, the motion controller adjusts the position of a welding torch.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10b
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• pp.1316-1321
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• 1990

Molten steel level information of ladle is very important for process control in steelmaking process. At secondary refining process, measuring lance and snokel have to keep constant thier depth from molten steel surfaces. But, there is much slag on the molten steel surface. Besides, not only the thickness of slag is varied with refining condition, but also molten steel level is largely affected by firebrick errosion. Then, optical measuring method and/or by human eyes cannot detect true molten steel surface, but slag surface. This slag thickness is 300mm at maximum, then huge diameter eddy current sensor will be needed if that type sensor is applied. In addition to, cooling system is necessary because the molten steel and slag temperature is high. This is not practically. To solve this problem, immersion type levelmeter is developed. This sensor is made up from primary and secondary cylindrical coils. High frequency current is applied to primary coil. Electro-motive force from secondary coil is measured, which is varied with molten steel level. This complete set is installed within stainless steel long capsule and attached to top of lance. This sensor is immersed into molten steel bath of ladle or tundish with protection of expendable paper sleeve.

• Journal of the Korean Magnetics Society
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• v.14 no.6
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• pp.207-212
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• 2004

Eddy current (EC) testing methods are widely used in a variety of applications including the inspection of steam generator tubes in nuclear power plants, aircraft parts and airframes. A key factor that affects the EC signal is lift-off which means the physical distance between a sensor and a specimen in the testing. In practice, it is difficult to keep track of the actual value of the lift -off during a specific experiment, simulation or testing in the field, which is essential for accurate interpretation of the signal to be used in the following steps. Hence it is necessary to have a scheme to render the EC signal invariant to the effects of lift-off in spite of the changes in the real world. This paper describes a new method for compensating EC signals for variations in lift-off by acquiring an invariance feature using a homomorphic operator and neural network techniques. The signals from various lift-offs are transformed to obtain a zero lift-off equivalent signal that can be subsequently used for defect characterization in the next step.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.9
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• pp.2082-2088
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• 1995

In this paper, we designed and fabricated the magnetic bearings and built-in type cylindrical capacitive transducers for improving the vibration characteristics of rotating shaft. The eddy current and magnetic field from the electromagnet of the bearing don't affect the measuring signal of the capacitive type transducers so that it is possible to locate the capacitive sensor plates around the magnetic bearing poles and can improve the spillover problem which is induced by the noncollocation of the sensors and actuators. According to the sensitivity calibration schemes using a X-Y table, the cylindrical capacitive transducers have a good linearities in the .+-.70.mu.m range from the geometric center of the sensor plates. The measured results also show high displacement sensitivities of the sensors. According to the performance test of the magnetic bearing which is controlled by the analog PD controllers, we found that the built-in capacitive transducer system successfully measures the journal displacement in the magnetic field and therefore the magnetic bearing system supports the rotating shaft up to 12,000 rpm.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.755-756
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• 2009