• Title/Summary/Keyword: 전류센서

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Properties of Exchange Bias Coupling Field and Coercivity Using the Micron-size Holes Formation Inside GMR-SV Film (GMR-SV 박막내 미크론 크기의 홀 형성을 이용한 교환결합세기와 보자력 특성연구)

  • Bolormaa, Munkhbat;Khajidmaa, Purevdorj;Hwang, Do-Guwn;Lee, Sang-Suk;Lee, Won-Hyung;Rhee, Jang-Roh
    • Journal of the Korean Magnetics Society
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    • v.25 no.4
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    • pp.117-122
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    • 2015
  • The holes with a diameter of $35{\mu}m$ inside the GMR-SV (giant magnetoresistance-spin valve) film were patterned by using the photolithography process and ECR (electron cyclotron resonance) Ar-ion milling. From the magnetoresistance curves of the GMR-SV film with holes measuring by 4-electrode method, the MR (magnetoresistance ratio) and MS (magnetic sensitivity) are almost same as the values of initial states. On other side hand, the $H_{ex}$ (exchange bias coupling field) and $H_c$ (coercivity) dominantly increased from 120 Oe and 10 Oe to 190 Oe and 41 Oe as increment of the number of holes inside GMR-SV film respectively. These results were shown to be attributed to major effect of EMD (easy magnetic domian) having a region positioned between two holes perpendicular to the sensing current. On the basis of this study, the fabrication of GMR-SV applying to the hole formation improved the magnetoresistance properties having the thermal stability and durability of bio-device.

Shape Magnetic Anisotropy on Magnetic Easy Axis of NiFe/Cu/NiFe/IrMn Spin Valve Thin Film (NiFe/Cu/NiFe/IrMn 스핀밸브 박막소자의 자화 용이축에 따른 형상 자기이방성)

  • Choi, Jong-Gu;Kwak, Tae-Joon;Lee, Sang-Suk;Sim, Jung-Taek
    • Journal of the Korean Magnetics Society
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    • v.20 no.2
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    • pp.35-40
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    • 2010
  • The GMR-SV (giant magnetoresistance-spin valve) device depending on the micro patterned features according to two easy directions of longitudinal and transversal axes has been studied. The GMR-SV multilayer structure was Ta(5 nm)/NiFe(8 nm)/Cu(2.3 nm)/NiFe(4 nm)/IrMn(8 nm)/Ta(2.5 nm). The applied anisotropy direction of the GMR-SV thin film was performed under the magnitude of 300 Oe using by permanent magnet during the deposition. The size of micro patterned device was a $1\;{\times}\;18\;{\mu}m^2$ after the photo lithography process. In the aspects of the shape magnetic anisotropy effect, there are two conditions of fabrication for GMR-SV device. Firstly, the direction of sensing current was perpendicular to the magnetic easy axis of the pinned NiFe/IrMn bilayer with the transversal direction of device. Secondly, the direction of shape magnetic anisotropy was same to the magnetic easy axis of the free NiFe layer with the longitudinal direction of device.

A small ocean bottom electromagnetometer and ocean bottom electrometer system with an arm-folding mechanism (Technical Report) (팔-접힘 구조를 가지는 소규모 OBEM과 OBE시스템 (기술보고서))

  • Kasaya, Takafumi;Goto, Tada-nori
    • Geophysics and Geophysical Exploration
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    • v.12 no.1
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    • pp.41-48
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    • 2009
  • Natural magnetic fields are attenuated by electrically conductive water. For that reason, marine magnetotelluric surveys have collected data at long periods (1000-100 000 s). The mantle structure has been the main target of seafloor magnetotelluric measurements. To ascertain crustal structure, however, electromagnetic data at shorter periods are important, e.g. in investigations of megathrust earthquake zones, or in natural resource surveys. To investigate of the former, for example, electromagnetic data for periods of less than 1000 s are necessary. Because no suitable ocean bottom electromagnetometer (OBEM) has been available, we have developed a small OBEM and ocean bottom electrometer (OBE) system with a high sample rate, which has an arm-folding mechanism to facilitate assembly and recovering operations. For magnetic observation, we used a fluxgate sensor. Field observations were undertaken to evaluate the field performance of our instruments. All instruments were recovered and their electromagnetic data were obtained. Results of the first experiment show that our system functioned well throughout operations and observations. Results of other field experiments off Tottori support the claim that the electromagnetic data obtained using the new OBEM and OBE system are of sufficient quality for the survey target. These results suggest that this device removes all instrumental obstacles to measurement of electromagnetic fields on the seafloor.

Improvement of PWM Driving Control Characteristics for Low Power LED Security Light (저전력형 LED 보안등의 PWM형 구동제어 특성 개선)

  • Park, Hyung-Jun;Kim, Nag-Cheol;Kim, In-Su
    • Journal of IKEEE
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    • v.21 no.4
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    • pp.368-374
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    • 2017
  • In this Paper, we developed a low power type LED security light using LED lighting that substitutes a 220[V] commercial power source for a solar cell module instead of a halogen or a sodium lamp. in addition, a PWM type drive control circuit is designed to minimize the heat generation problem and the drive current of the LED drive controller. in developed system, The light efficiency measurement value is 93.6[lm/W], and a high precision temperature sensor is used inside the controller to control the heat generation of the LED lamp. In order to eliminate the high heat generated from the LED lamp, it is designed to disperse quickly into the atmosphere through the metal insertion type heat sink. The heat control range of LED lighting was $50-55[^{\circ}C]$. The luminous flux and the lighting speed of the LED security lamp were 0.5[s], and the beam diffusion angle of the LED lamp was about $110[^{\circ}C]$ by the light distribution curve based on the height of 6[m].

A Study On Design of ZigBee Chip Communication Module for Remote Radiation Measurement (원격 방사선 측정을 위한 ZigBee 원칩형 통신 모듈 설계에 대한 연구)

  • Lee, Joo-Hyun;Lee, Seung-Ho
    • Journal of IKEEE
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    • v.18 no.4
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    • pp.552-558
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    • 2014
  • This paper suggests how to design a ZigBee-chip-based communication module to remotely measure radiation level. The suggested communication module consists of two control processors for the chip as generally required to configure a ZigBee system, and one chip module to configure a ZigBee RF device. The ZigBee-chip-based communication module for remote radiation measurement consists of a wireless communication controller; sensor and high-voltage generator; charger and power supply circuit; wired communication part; and RF circuit and antenna. The wireless communication controller is to control wireless communication for ZigBee and to measure radiation level remotely. The sensor and high-voltage generator generates 500 V in two consecutive series to amplify and filter pulses of radiation detected by G-M Tube. The charger and power supply circuit part is to charge lithium-ion battery and supply power to one-chip processors. The wired communication part serves as a RS-485/422 interface to enable USB interface and wired remote communication for interfacing with PC and debugging. RF circuit and antenna applies an RLC passive component for chip antenna to configure BALUN and antenna impedance matching circuit, allowing wireless communication. After configuring the ZigBee-chip-based communication module, tests were conducted to measure radiation level remotely: data were successfully transmitted in 10-meter and 100-meter distances, measuring radiation level in a remote condition. The communication module allows an environment where radiation level can be remotely measured in an economically beneficial way as it not only consumes less electricity but also costs less. By securing linearity of a radiation measuring device and by minimizing the device itself, it is possible to set up an environment where radiation can be measured in a reliable manner, and radiation level is monitored real-time.

Characteristics of a planar Bi-Sb multijunction thermal converter with Pt-heater (백금 히터가 내장된 평면형 Bi-Sb 다중접합 열전변환기의 특성)

  • Lee, H.C.;Kim, J.S.;Ham, S.H.;Lee, J.H.;Lee, J.H.;Park, S.I.;Kwon, S.W.
    • Journal of Sensor Science and Technology
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    • v.7 no.3
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    • pp.154-162
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    • 1998
  • A planar Bi-Sb multijunction thermal converter with high thermal sensitivity and small ac-dc transfer error has been fabricated by preparing the bifilar thin film Pt-heater and the hot junctions of thin film Bi-Sb thermopile on the $Si_{3}N_{4}/SiO_{2}/Si_{3}N_{4}$-diaphragm, which functions as a thermal isolation layer, and the cold junctions on the dielectric membrane supported with the Si-substrate, which acts as a heat sink, and its ac-dc transfer characteristics were investigated with the fast reversed dc method. The respective thermal sensitivities of the converter with single bifilar heater were about 10.1 mV/mW and 14.8 mV/mW in the air and vacuum, and those of the converter with dual bifilar heater were about 5.1 mV/mW and 7.6 mV/mW, and about 5.3 mV/mW and 7.8 mV/mW in the air and vacuum for the inputs of inside and outside heaters, indicating that the thermal sensitivities in the vacuum, where there is rarely thermal loss caused by gas, are higher than those in the air. The ac-dc voltage and current transfer difference ranges of the converter with single bifilar heater were about ${\pm}1.80\;ppm$ and ${\pm}0.58\;ppm$, and those of the converter with dual bifilar heater were about ${\pm}0.63\;ppm$ and ${\pm}0.25\;ppm$, and about ${\pm}0.53\;ppm$ and ${\pm}0.27\;ppm$, respectively, for the inputs of inside and outside heaters, in the frequency range below 10 kHz and in the air.

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Growth of CdSe thin films using Hot Wall Epitaxy method and their photoelectrical characteristics (HWE방법에 의한 CdSe 박막 성장과 광전기적 특성)

  • Hong, K.J.;Lee, K.K.;Lee, S.Y.;You, S.H.;Shin, Y.J.;Suh, S.S.;Jeong, J.W.;Jeong, K.A.;Shin, Y.J.;Jeong, T.S.;Kim, T.S.;Moon, J.D.;Kim, H.S.
    • Journal of Sensor Science and Technology
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    • v.6 no.4
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    • pp.328-336
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    • 1997
  • The CdSe thin films were grown on the Si(100) wafers by a hot wall epitaxy method (HWE). The source and substrate temperature are $600^{\circ}C$ and $430^{\circ}C$ respectively. The crystalline structure of epilayers was investigated by double crystal X-ray diffraction(DCXD). Hall effect on the sample was measured by the van der Pauw method and studied on the carrier density and mobility dependence on temperature. From Hall data, the mobility was increased in the temperature range 30K to 150K by impurity scattering and decreased in the temperature range 150k to 293k by the lattice scattering. In order to explore the applicability as a photoconductive cell, we measured the sensitivity(${\gamma}$), the ratio of photocurrent to darkcurrent(pc/dc), maximum allowable power dissipation(MAPD), spectral response and response time. The results indicated that the photoconductive characteristic were the best for the samples annealed in Cu vapor compare with in Cd, Se, air and vacuum vapour. Then we obtained the sensitivity of 0.99, the value of pc/dc of $1.39{\times}10^{7}$, the MAPD of 335mW, and the rise and decay time of 10ms and 9.5ms, respectively.

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A 12b 200KHz 0.52mA $0.47mm^2$ Algorithmic A/D Converter for MEMS Applications (마이크로 전자 기계 시스템 응용을 위한 12비트 200KHz 0.52mA $0.47mm^2$ 알고리즈믹 A/D 변환기)

  • Kim, Young-Ju;Chae, Hee-Sung;Koo, Yong-Seo;Lim, Shin-Il;Lee, Seung-Hoon
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.43 no.11 s.353
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    • pp.48-57
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    • 2006
  • This work describes a 12b 200KHz 0.52mA $0.47mm^2$ algorithmic ADC for sensor applications such as motor controls, 3-phase power controls, and CMOS image sensors simultaneously requiring ultra-low power and small size. The proposed ADC is based on the conventional algorithmic architecture with recycling techniques to optimize sampling rate, resolution, chip area, and power consumption. The input SHA with eight input channels for high integration employs a folded-cascode architecture to achieve a required DC gain and a sufficient phase margin. A signal insensitive 3-D fully symmetrical layout with critical signal lines shielded reduces the capacitor and device mismatch of the MDAC. The improved switched bias power-reduction techniques reduce the power consumption of analog amplifiers. Current and voltage references are integrated on the chip with optional off-chip voltage references for low glitch noise. The employed down-sampling clock signal selects the sampling rate of 200KS/s or 10KS/s with a reduced power depending on applications. The prototype ADC in a 0.18um n-well 1P6M CMOS technology demonstrates the measured DNL and INL within 0.76LSB and 2.47LSB. The ADC shows a maximum SNDR and SFDR of 55dB and 70dB at all sampling frequencies up to 200KS/s, respectively. The active die area is $0.47mm^2$ and the chip consumes 0.94mW at 200KS/s and 0.63mW at 10KS/s at a 1.8V supply.