• Title/Summary/Keyword: Eddy Current Sensor System

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In-Process Measurement of ELID Grinding Status -Thickness of Insulating layer-

  • Ahn, Jung-Hwan;Kim, Hwa-Young;Seo, Young-Ho;Paik, In-Hwan
    • Journal of Mechanical Science and Technology
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    • v.15 no.9
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    • pp.1268-1273
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    • 2001
  • To successfully establish the ELID-grinding, it is important to properly select the electrolytic condition according to grinding conditions. Currently, the selection of electrolytic condition is mainly dependent on the operators experience, which is one of difficulties preventing the successful application of ELID technique. In this study, an in-process measurement system of the insulating layer using two gap sensors-a capacitance type and an eddy current type-are developed and the change of the thickness of insulating layer during ELID grinding is detected. Evaluation experiments show the possibility to control the electrolytic condition through the in-process measurement of the layer status.

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Application and Design of Eddy Current based on FEM for NDE Inspection of Surface Cracks with Micro Class in Vehicular Parts (자동차부품의 마이크로급 표면크랙 탐상을 위한 FEM 를 기반한 와전류 센서 디자인 및 적용)

  • Im, Kwang-Hee;Lee, Seul-Ki;Kim, Hak-Joon;Song, Sing-Jin;Woo, Yong-Deuk;Na, Sung-Woo;Hwang, Woo-Chae;Lee, Hyung-Ho
    • Journal of the Korean Society for Precision Engineering
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    • v.32 no.6
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    • pp.529-536
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    • 2015
  • A defect could be generated in bolts for a use of oil filters for the manufacturing process and then may affect to the safety and quality in bolts. Also, fine defects may be imbedded in oil filter system. So it is very important that such defects be investigated and screened during the multiple manufacturing processes. Therefore, in order effectively to evaluate the fine defects, the FEM simulations were performed to make characterization in the crack detection of the bolts and the parameters such as number of turns of the coil, the coil size, applied frequency were calculated based on the simulation results. Simulations were carried out for the defect signal of eddy current probe. Exciter and receiver were utilized. In this paper, the FEM simulations were performed in both bobbin-type and pancake-type probe, both probes were optimized under Eddy current FEM simulations and the results of calculation were discussed.

An Inductive Position Sensor for Self-sensing Magnetic Suspension System (셀프센싱 자기 부상계를 위한 인덕턴스형 변위센서)

  • 윤형진;이상헌;백윤수
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2003.06a
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    • pp.1038-1041
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    • 2003
  • The magnetic suspension system is used in many areas, because it has great advantages. such as no friction, no noise, no lubrication and so on, but it is a unstable system in natural. It must have a feedback control with the position is measured for a stable levitation. There are an eddy-current sensor, a capacitive sensor, an inductive sensor, and an optical sensor with a laser as the sensor which measures displacements without contact. Among them, an inductive sensor is made with lower price than others. And it has a good linearity. In this paper, a magnetic circuit leads a linear equation between an input as a displacement and an output as a voltage. Experiments establish that voltage change according to displacement is linear. This paper presents the preliminary study of an inductive position sensing for self-sensing magnetic suspension system.

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Runout Control of a Magnetically Suspended High Speed Spindle Using Adaptive Feedforward Method (적응 Feedforward를 이용한 자기베어링 고속 주축계의 전기적 런아웃 제어)

  • 노승국;경진호;박종권
    • Journal of the Korean Society for Precision Engineering
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    • v.19 no.12
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    • pp.57-63
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    • 2002
  • In this paper, the feedforward control with least mean square (LMS) adaptive algorithm is proposed and examined to reduce rotating error by runout of an active magnetic bearing system. Using eddy-current type gap sensor fur control, the electrical runout caused by non-uniform material properties of sensor target produces rotational error amplified in feedback control loop, so this runout should be eliminated to increase rotating accuracy. The adaptive feedforward controller is designed and examined its tracking and stability performances numerically with established frequency response function. The tested grinding spindle system is manufactured with a 5.5 ㎾ internal motor and 5-axis active magnetic bearing system including 5 eddy current gap sensors which have approximately 15 ~ 30 ${\mu}{\textrm}{m}$ of electrical runout. According to the experimental analysis, the error signal in radial bearings is reduced to less than 5 ${\mu}{\textrm}{m}$ when it is rotating up to 50,000 rpm due to applying the feedforward control for first order harmonic frequency, and vibration of the spindle base is also reduced about same frequency.

A Helmet-type MEG System with $1^{st}$ order SQUID Gradiometer Located in Vacuum (진공조에 위치한 1차 SQUID 미분계를 이용한 헬멧형 뇌자도 장치의 제작)

  • Yu, K.K.;Kim, K.;Lee, Y.H.;Kim, J.M.
    • Progress in Superconductivity
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    • v.11 no.1
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    • pp.78-82
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    • 2009
  • We have fabricated a helmet type magnetoencephalogrphy(MEG) with a $1^{st}$ order gradiometer in vacuum to improve the signal-to-noise ratio(SNR) and the boil-off rate of liquid helium(LHe). The axial type first-order gradiometer was fabricated with a double relaxation oscillation SQUID(DROS) sensor which was directly connected with a pickup coil. The neck space of LHe dewar was made to be smaller than that of a conventional dewar, but the LHe boil-off ratio appeared to increase. To reduce the temperature of low Tc SQUID sensor and pickup coil to 9 K, a metal shield made of, such as copper, brass or aluminum, have been usually used for thermal transmission. But the metal shield exhibited high thermal noise and eddy current fluctuation. We quantified the thermal noise and the eddy current fluctuation of metal. In this experiment, we used the bobbin which was made of an alumina to wind Nb superconductive wire for pickup coil and the average noise of coil-in-vacuum type MEG system was $3.5fT/Hz^{1/2}$. Finally, we measured the auditory evoked signal to prove the reliability of coil-in-vacuum type MEG system.

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Development of Deterioration Diagnosis System for Aged ACSR-OC Conductors in HV Overhead Distribution Lines (고압 가공배전선의 노화된 ACSR-OC 도체에 대한 열화진단시스템 개발)

  • 김성덕;이승호
    • 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.

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A study on the optimal conditions for machining accuracy when endmill fillet cutting at the corner (코너부 모깍기 엔드밀가공시 가공정밀도의 최적조건에 관한 연구)

  • Choi, Sung-Yun;Kwon, Dae-Gyu;Park, In-Su;Wang, Duck-Hyun
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.15 no.4
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    • pp.101-108
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    • 2016
  • Endmill fillet cutting at the corner was conducted with the online measurement of cutting forces and tool deflection by a tool dynamometer and an eddy current sensor system. The profile of the machined surface was also compared with the CAD profile with a Coordinate Measuring Machine (CMM) and CALYPSO software. It was found that the end mill cutter with four blades has a better surface profile than that with two blades, and the cutting forces and tool deformation were increased as the cutting speed was increased. When the tool located at the degree $45^{\circ}$ corner was found to conduct the maximum cutting force than started to the point of the workpiece. As it was compared with the CMM and ANOVA analysis result in the case that the cutting force and tool deformation was the maximum, it was found that the result was affected by the spindle speed and the number of blades.

The Organization of Rotational Accuracy Measurement System of NC Lathe Spindle (NC 선반 주축의 회전정도 측정 시스템의 구성)

  • Kim, Young-Seuk
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.14 no.5
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    • pp.21-26
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    • 2005
  • It is important to measure the rotational accuracy of NC lathe spindle as it affects to the qualities of all machines machined by the NC lathe using in industries. The bad rotational accuracy of NC lathe spindle are caused mainly by wearness of the spindle in using and quality of spindle when machining and using low level bearings. It occurs especially in case of NC lathes because the cutting force acting to work-piece act on one side to the spindle not to both sides symmetrically. Therefore in this study, constructing experimental appratus for measuring of rotational accuracy by using eddy current type gap sensors, converters, screw terminal, data acquisition board inserted in computer and software f3r data acquisition, DT VEE ver. 5.0 and then error data acquired in the rotational accuracy test of NC lathe spindle are analysed in plots and statistical treatments.

Real-time wafer thin-film thickness measurement system implementation with eddy current sensors. (와전류센서를 이용한 실시간 웨이퍼 박막두께측정 시스템 구현)

  • Kim, Nam-woo;Hur, Chang-Wu
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2013.10a
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    • pp.383-385
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    • 2013
  • 반도체소자의 고속실현을 위해서 알루미늄배선에서 40% 가량 성능을 높이는 반면 제조비용은 30%까지 낮출 수 있는 구리를 선호하고 있으나, 식각이 잘 되지 않아 원하는 패턴으로 만들어 내기가 곤란한 공정기술의 어려움과 구리물질이 지닌 유독성문제를 가지고 있다. 기존의 식각기술로는 구리패턴을 얻을 수 없는 기술적 한계 때문에 화학.기계적 연마(CMP)를 이용한 평탄화와 연마를 통해서 구리배선을 얻는 다마스커스(Damascene)기술이 개발됐고 이를 이용한 구리배선기술이 현실적으로 가능하게 됐다. CMP를 이용한 평탄화 및 연마 공정에서 Wafer에 도포된 구리의 두께를 실시간으로 측정하여 정밀하게 제어할필요가 있는데, 본 논문에서는 와전류를 이용하여 옹고스트롬 단위의 두께를 실시간으로 측정하여 제어 하는 시스템구현에 대해 기술한다.

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