• 한국초전도ㆍ저온공학회논문지
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• 제11권3호
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• pp.26-30
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• 2009

Korea Superconducting Tokamak Advanced Research(KSTAR) device is composed of 30 superconducting magnets, magnet structure, vacuum vessel, cryostat, current feeder system, and etc. KSTAR device is operated in the cryogenic temperature and high magnetic field. We install about 800 sensors - temperature sensors, stain gages, displacement gages, hall sensors - to monitor the thermal, mechanical, electrical status of KSTAR during operation. As a tremendous numbers of sensors should be installed for monitoring the KSTAR device, the method of effective installation was developed. The sensor test was successfully carried out to check its reliability and its reproduction in the cryogenic temperature. The sensor signal is processed by PXI-based DAQ system and communicated with central control system via machine network and is shown by Operator Interface(OPI) display in the main control room. In order to safely operate the device, any violations of mechanical & superconductive characteristic of the device components were informed to its operation system & operator. If the monitored values exceed the pre-set values, the protective action should be taken against the possible damage. In this paper, the system composition, operation criteria, operation result were presented.

• 한국정밀공학회지
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• 제20권4호
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• pp.68-75
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• 2003

This paper introduces the development of hydraulic cylinder with magnetic sensors detecting absolute and precise position for automation of excavator. The system which is developed can detect absolute position with a little displacement by using algorithm for recognizing datum points, 114 divider algorithm and high precision algorithm improved position precision. We alse evaluate the developed system under the load disturbance and add band pass filter to the previous's signal process circuit for the protecting magnetic sensors's saturation.

• Smart Structures and Systems
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• 제25권1호
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• pp.57-64
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• 2020

The nonlinear dynamics of a directly forced clamped-clamped-free-free magneto-rheological elastomer (MRE) sandwich shell has been experimentally investigated. Experiments have been conducted on an aluminium shallow shell (shell A) and an MRE-aluminium sandwich shallow shell with single curvature (shell B). An electrodynamic shaker has been used to directly force shells A and B in the vicinity of their fundamental resonance frequency; a laser displacement sensor has been used to measure the vibration amplitude to construct the frequency-response curves. It was observed that for an aluminium shell (shell A), that at small forcing amplitudes, a weak softening-type nonlinear behaviour was observed, however, at higher forcing amplitudes the nonlinear dynamical behaviour shifted and a strong hardening-type response occurred. For the MRE shell (shell B), the effect of forcing amplitude showed softening at low magnetic fields and hardening for medium magnetic fields; it was also observed the mono-curved MRE sandwich shell changed dynamics to quasiperiodic displacement at some frequencies, from a periodic displacement. The presence of a magnetic field, initial curvature, and forcing amplitude has significant qualitative and quantitative effects on the nonlinear dynamical response of a mono curved MRE sandwich shell.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 G
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• pp.2986-2988
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• 1999

This paper presents a new concept to implement and to control of tactile reproduction simulator by implementation of compliance emulator system. Compliance emulator system is a kind of levitation system using magnetic force. In the compliance emulator system, a floated plate moves vertically. When an external force is applied to the plate, the system produces a controlled reaction force by using 6 electromagnet. For the control, a LVDT displacement sensor and PD control method is used.

• 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.

• Structural Engineering and Mechanics
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• 제17권3_4호
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• pp.303-329
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• 2004

Magnetostrictive materials are routinely employed as actuator and sensor elements in a wide variety of noise and vibration control problems. In infrastructural applications, other technologies such as hydraulic actuation, piezoelectric materials and more recently, magnetorheological fluids, are being favored for actuation and sensing purposes. These technologies have reached a degree of technical maturity and in some cases, cost effectiveness, which justify their broad use in infrastructural applications. Advanced civil structures present new challenges in the areas of condition monitoring and repair, reliability, and high-authority actuation which motivate the need to explore new methods and materials recently developed in the areas of materials science and transducer design. This paper provides an overview of a class of materials that because of the large force, displacement, and energy conversion effciency that it can provide is being considered in a growing number of quasistatic and dynamic applications. Since magnetostriction involves a bidirectional energy exchange between magnetic and elastic states, magnetostrictive materials provide mechanisms both for actuation and sensing. This paper provides an overview of materials, methods and applications with the goal to inspire novel solutions based on magnetostrictive materials for the design and control of advanced infrastructural systems.

• 한국생산제조학회지
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• 제23권3호
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• pp.266-272
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• 2014

This study proposes a closed-loop shaping control method with $H_{\infty}$ optimization for optical image stabilization (OIS) in mobile phone cameras. The image stabilizer is composed of a horizontal stage constrained by ball bearings and actuated by the magnetic force from voice coil motors. The displacement of the stage is measured by Hall effect sensors. From the OIS frequency response experiment, the transfer function models of the stage and Hall effect sensor were identified. The weight functions were determined considering the tracking performance, noise attenuation, and stability with considerable margins. The $H_{\infty}$ optimal controller was executed using closed-loop shaping and limiting the controller order, which should be less than 6 for real-time implementation. The control algorithm was verified experimentally and proved to operate as designed.

• 한국자기학회지
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• 제17권4호
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• pp.156-161
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• 2007

어레이(away) 자성센서 개발을 위해 고진공 스퍼터링 증착장비를 이용하여 스펙큘러형(specular type) Glass/Ta(5)/NiFe(7)/IrMn(10)/NiFe(5)/$O_2$/CoFe(5)/Cu(2.6)/CoFe(5)/$O_2$/NiFe(7)/Ta(5)(nm) 거대자기저항-스핀밸브(giant magnetoresistive-spin valves; CMR-SV)박막을 제작하였다. 다층박막 시료를 $20{\times}80{\mu}m^2$의 미세 활성영역을 가진 15개 어레이를 $8{\times}8mm^2$ 영역 내에 최적화한 제작 조건으로 광 리소그래피 패터닝 하였다. Cu를 증착하여 만든 2단자 전극법으로 측정한 자성특성은 15개 모든 소자들이 균일한 자기저항특성을 나타내었고, 5 Oe 근방에서 가장 민감한 자기저항비 자장민감도와 출력전압들은 각각 0.5%/Oe, ${\triangle}$V: 3.9 mV이었다. 형상자기이방성이 적용된 상부 자유층 $CoFe/O_2/NiFe$층은 하부 고정 자성층 $IrMn/NiFe/O_2/CoFe$층 자화 용이축과 직교하였다. 측정시 인가전류 값을 각각 1 mA에서 10 mA까지 인가하였을 때 출력 작동 전압 값은 균일하게 증가하였으며, 자장감응도도 거의 일정하여 미세 외부자장에 민감한 나노자성소자로서 좋은 특성을 띠었다.

• 대한기계학회논문집A
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• 제39권10호
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• pp.995-999
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• 2015

자기유도(inductive) 센서는 원리가 간단하고 경제적이어서 변위, 힘, 압력 등 다양한 물리량 측정에 사용된다. 본 논문에서는 고리 모양의 강판과 코일로 이루어진 간단한 구조의 자기유도 센서를 제안하였다. 센서의 인덕턴스를 자기회로 방법을 이용하여 추정하고 유한요소 해석을 통해 검증하였다. 고리의 고유 진동수를 Castigliano 정리와 등가 질량 방법을 이용하여 추정하고 실험 및 유한요소 해석을 통해 검증하였다. 기계적 진동에 영향을 주지 않도록 센서의 가진 주파수를 결정하였으며, 구동 및 신호처리 회로를 설계하여 센서를 제작하였다. 제작된 자기유도 센서를 유연관 내부의 유체 압력을 비침습적으로 측정하는데 활용하였다. 압력과 센서 출력 간의 관계를 이차식 형태로 표현하면 2% 이내의 정확도로 압력을 측정할 수 있어 압력 센서로서의 가능성을 확인하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 심포지엄 논문집 정보 및 제어부문
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• pp.377-379
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• 2007

To reduce the chattering errors of reed switch sensors used for automatic remote measurement of water supply system, a reed switch sensor was analyzed and improved. The operation of reed switch sensors can be described as a mechanical contact by approximation of permanent magnet piece to generate an electrical pulse. The reed switch sensors are used in measurement application by detecting the rotational or translational displacement. To apply for flow measurement devices, the reed switch sensors should keep high reliability. They are applied for the electronic digital type of water flow meters. The reed switch sensor is just installed simply on the mechanical type flow meter. A small magnet is attached on a pointer of the water meter counter rotor. Inside the reed sensor, two steel leaf springs make mechanical contact and apart as rotation of flow meter counter. The counting electrical contact pulses can be converted as the water flow amount. The MCU sends the digital flow rate data to the server using the wireless communication network. But it occurs data difference or errors by chattering noise. The reed switch sensor contains chattering error by it self at the force equivalent position. The vibrations such as passing car near to the switch sensor installed location. In order to reduce chattering error, most system uses just software methods for example using filter and also statistical calibration methods. The chattering errors were reduced by changing leaf spring structure using mechanical hysteresis characteristics.