• 한국소음진동공학회논문집
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• 제17권3호
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• pp.235-240
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• 2007

In this work, the operational deflection shape(ODS) of an automobile exhaust system is measured by using a recently-developed magnetic sensor. The magnetic sensor is composed of a solenoid and two pairs of permanent magnets generating an antisymmetric magnetic field in the lateral direction inside the solenoid. Lateral movement of a ferromagnetic pipe inside the magnetic field of the suggested sensor induces an electromotive force in the solenoid corresponding to the lateral velocity of the pipe. Due to the simplicity and non-contact characteristics of the magnetic sensor, dynamic behaviors of the structures operating under high temperature such as an exhaust pipe can be efficiently observed. It is shown that the lateral ODS of an exhaust system can be successfully measured by the suggested sensors.

• 센서학회지
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• 제24권3호
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• pp.181-187
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• 2015

The magnetoelectric characteristics on layered $Fe_{78}B_{13}Si_9/PZT$ and $Fe_{78}B_{13}Si_9/PZT/Fe_{78}B_{13}Si_9$($t_m=0.017$, 0.034mm) composites by epoxy bonding for magnetic field sensor were investigated in the low-frequency range and resonance frequency range. The optimal bias magnetic field $H_{dc}$ of these samples was about 23~63 Oe range. The Me coefficient of $Fe_{78}B_{13}Si_9/PZT/Fe_{78}B_{13}Si_9(t_m=0.034mm)$ composites reaches a maximum of $186mV/cm{\cdot}Oe$ at $H_{dc}=63Oe$, f=50 Hz and a maximum of $1280mV/cm{\cdot}Oe$ at $H_{dc}=63Oe$, resonance frequency $f_r=95.5KHz$. The output voltage shows linearity proportional to ac fields $H_{ac}$ and is about U=0~130.6 mV at $H_{ac}=0{\sim}7Oe$, f=50 Hz, U=0~12.4 V at $H_{ac}=0{\sim}10Oe$, $f_r=95.5KHz$(resonance frequency). The optimal frequency(f=50 Hz) of this sample is around the utility ac frequency(f=60 Hz). Therefore, this sample will allow for ac magnetic field sensor at utility frequency and low bias magnetic fields $H_{dc}$.

• Progress in Superconductivity
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• 제8권1호
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• pp.122-126
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• 2006

This paper presents experimental and numerical investigation on heat generation of a bulk HTS for application to a 100 kWh Superconductor Flywheel Energy Storage System(SFES) bearing. An experimental device is manufactured to reproduce varying magnetic field conditions that a bulk HTS may experience during the operation of the 100 kWh SFES. The bulk HTS is directly cooled by a cryocooler while the heat is generated by the eddy currents created by varying magnetic fields induced by a coil. In order to design the cryocooling system for the 100 kWh SFES project, a preliminary experiment to investigate the actual cooling load variation under AC magnetic field has been carried out. In the experiment, two different copper holders were designed and tested. Several temperature sensors were installed on each component of the assembly and the temperatures were measured for several operating conditions of the 100 kWh SFES. The experimental investigation on the thermal response of the bulk HTS and its holder is considered to be a valuable step fur the successful materialization of a large-scale SFES.

• Progress in Superconductivity
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• 제8권2호
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• pp.158-163
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• 2007

YBCO do superconducting quantum interference device (SQUID) magnetometers based on bicrystal junctions have been fabricated for magnetocardiograph (MCG) measurements. We could fabricate YBCO SQUID magnetometers having magnetic field noise of about $20fT/Hz^{1/2}$ at white noise region. We have developed an MCG system employing the high performance SQUID magnetometers. The lightweight MCG system, requiring liquid nitrogen as a coolant, consists of 6-channel SQUID sensors, an adjustable patient bed with sliding motion, and data analyses software. The MCG system could record quite clear MCG signals in a room with moderate magnetic shielding. In normal operation with multi-position MCG measurements, we could obtain clear 48-point mappings of magnetic field map and current source map with high enough signal qualities far clinical trials.

• 센서학회지
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• 제5권2호
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• pp.29-36
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• 1996

본 논문에서는 전기기기 및 전력설비의 운전 조작중에 발생하는 극저주파 영역(ELF)의 자장을 측정 및 분석 할 수 있는 장치로써 멀티턴 루우프형 센서를 이용한 3차원 자장측정계에 대해 기술한다. 저주파특성의 개선과 왜곡없는 공간자장성분의 측정 등 우수한 성능을 얻기 위해서, 자장측정계를 멀티턴 루우프형 센서와 증폭기, 능동성 적분기로 구성하여 3차원적으로 설계 제작하였다. 교정실험을 통하여 측정계의 고유응답특성을 산출한 결과, 주파수대역은 x, y, z 축 각각 8[Hz]에서 53[kHz] 정도이고, 응답감도는 9.54, 9.21, $10.89[mV/{\mu}T]$이다. 진동성 임펄스전류발생기를 이용한 적용실험으로써 측정계의 신뢰성을 확인하였고, 소형 전등기의 기동시에 발생하는 자장과 측정거리에 따른 정상운전중의 자장특성을 측정 분석한 결과 자장의 세기는 각각 최대 15.8, $8.61[{\mu}T]$이며, 거리가 증가할수록 급격한 감소를 보였다.

• 센서학회지
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• 제19권6호
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• pp.475-482
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• 2010

Rogowski coil which detects magnetic flux on current changes. It is used for digital integration with watt-hour meter's current sensor, because, Rogowski coil has non-cored or non-magnetic core structure, so that, it cannot be saturated magnetically. This is a study for inventing accurate electric current sensors that have been applied on multi-layer ceramic substrate. We have confirmed its properties from each different layer's materials and pattern sizes by MWS 3D Electromagnetic field analysis program. And, after sensor manufacturing on multi-layer ceramic substrate, we confirmed its sensing quality is reliable as accurate electric current sensor for watt-hour meter.

• 동력기계공학회지
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• 제11권2호
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• pp.72-76
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• 2007

Since the magnetic bearing system has unstability inherently it is necessary to measure the displacement for stable operation. Normally the displacement measurement is implemented by using sensors. The sensor for the displacement measurement is selected by precision, installation space, effect of magnetic field and response speed. And the cost of displacement measurement sensor also is considered. At the cost the hall effect sensor has a large advantage comparing with the others. Therefore this study concern about the basis experimental test for the displacement measurement of the magnetic bearing system that uses the hall effect sensor coupled with a tiny permanent magnet. The experimental results confirm the validity and practicability for this displacement measurement sensor.

• 제어로봇시스템학회논문지
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• 제14권2호
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• pp.118-124
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• 2008

Recently fishing industry is interested in efficiency and automation to acquire the international competitive power of national fishing industry. As an automation device of fishing boat, there are electric compasses using GPS and terrestrial magnetic sensor. Electric compass can be minimum size, high effectiveness with keeping the characteristic of a magnetic compass. This can be used a heading angle sensor to construct auto-navigation system in a small size ship. This paper develop electronic compass system that has serial output signal in NMEA 0183 and demonstrates the possibility of the electronics compass in navigation system for a small sized ship.

• Journal of Mechanical Science and Technology
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• 제17권12호
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• pp.1835-1843
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• 2003

This paper introduces the development of the caliper system for a geometry PIG (Pipeline Inspection Gauge). The objective of the caliper system is to detect and measure dents, wrinkles, and ovalities affect the pipe structural integrity. The developed caliper system consists of a finger arm, an anisotropic permanent magnet, a back yoke, pins, pinholes and a linear hall effect sensor. The angle displacement of the finger arm is measured by the change of the magnetic field in sensing module. Therefore the sensitivity of the caliper system mainly depends on the magnitude of the magnetic field inside the sensing module. In this research, the ring shaped anisotropic permanent magnet and linear hall effect sensors were used to produce and measure the magnetic field. The structure of the permanent magnet, the back yoke and pinhole positions were optimized that the magnitude of the magnetic field range between a high of 0.1020 Tesla and a low of zero by using three dimensional nonlinear finite element methods. A simulator was fabricated to prove the effectiveness of the developed caliper system and the computational scheme using the finite element method. The experimental results show that the developed caliper system is quite efficient for the geometry PIG with good performance.

• 대한교통학회지
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• 제23권5호
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• pp.123-134
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• 2005

본 연구는 기존의 루프검지기의 설치 및 유지보수를 위한 성능평가 방법으로서 사용해왔던 L-R-C(Inductance-Resistance-Capacitance) Test에 의한 Q Factor(질 계수)방법을 대체/보완할 수 있는 새로운 방법에 대한 연구이다. 기존의 Q Factor방법은 크게 세 가지 문제점을 수반하고 있다. 첫째, 현장의 루프검지기의 전기적 특성인 L-R-C값을 Q Factor를 기준으로 루프검지기의 현재 성능을 평가함으로써 인력에 의존하는 효율성에 문제를 안고 있으며 둘째, 루프검지시스템의 전체를 대상으로 하지 않고 일부의 측정치만으로 전체시스템을 추론하고 있다는 점과 셋째, 기존의 방법으로는 루프검지기의 검지영역, 즉 높이별 검지영역를 알 수 없다는 것이다. 따라서 본 연구에서는 이러한 문제점을 보완할 수 있는 방법으로서 루프검지기헤드에서 발생하는 자기장을 측정하여 루프검지기 전체시스템의 현재상태를 파악하고자 하였다. 이를 위하여 루프검지기에서 생성되는 자기장을 검출할 수 있는 센서와 자료수집방법, 분석방법 및 진단방법 등을 개발하였다.