• Journal of the Korean Magnetics Society
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• v.15 no.1
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• pp.48-52
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• 2005

This paper describes a current sensor for precision current measurement of an electronic watt-hour meter that is going to install in houses in the future. As the current sensor is based on an cored principle (the Rogowski principle) it is not subject to usual limitations of saturation and non-linearity of general current transformers. An advantage of the developed current sensor is that non-linearity error in low current range is improved and the construction can be kept simple using an air core. We present a magnetic field analysis of the sensor using a finite-element solver. We compared the measured values versus the calculated values.

• Journal of the Korean Magnetics Society
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• v.23 no.2
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• pp.49-53
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• 2013

A current sensor is one of important component which is used for the electrical current measurement during charge and discharge of the battery, and monitoring system of the motor controller in the electric and hybrid vehicle. In this study, we have developed an open loop type current sensor using GaAs Hall sensor and magnetic core has an air gap. The Hall sensor detect magnetic field produced by the current to be measured. The 3 mm air gap core was made by HGO electrical steel sheets after slitting, winding, annealing, molding, and cutting. Developed current sensor shows 0.03 % linearity within DC current range from -400 A to +400 A. Operating temperature range was extended to the range of $-40{\sim}105^{\circ}C$ using temperature compensating electronic circuit. To Improve frequency bandwidth limit due to the air flux of PCB (Printed Circuit Board) and Hall sensor, We employed an air flux compensating loop near Hall sensor or on PCB. Frequency bandwidth of the sensor was 100 kHz when we applied sine wave current of $40A{\cdot}turn$ in the frequency range from 100 Hz to 100 kHz. For the dynamic response time measurement, 5 kHz square wave current of $40A{\cdot}turn$ was applied to the sensor. Response time was calculated time reach to 90 % of saturation value and smaller than $2{\mu}s$.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.12
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• pp.95-100
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• 2008

Conventional Earth Leakage Circuit Breakers (ELCBs) have defects of a breaking failure or a long breaking-time against parallel arc current. In this paper, breaking characteristics of conventional ELCBs were analyzed by simulation of parallel arc in a low-voltage indoor wiring system, and an air-core current sensor and a signal converter being most available for parallel arc detection were developed and applied to a conventional ELCB. The proposed tripped the ELCB regardless of the location of parallel arc. The breaking-time was in ranges of $1.74{\sim}8.3[ms]$ depending on the phase of arc generation, which is about 5 times as fast as conventional ELCBs with the breaking-time of 50[ms].

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05c
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• pp.47-50
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• 2001

Conventionally, air-cored Rogowski coil was designed for use as high alternating and transient current sensor without saturation caused by ferromagnetic material in its core. This paper investigated that Rogowski coil can be applied to low current measurement in 60Hz power line. Measured parameters R, L of coil were compared with theoretically calculated values. Output voltages crossed by Rogowski coil have shown some linearity according to input current(tens to thousands of amperes) passing through it. And also shielding effect for external noises was investigated for three cases.

• Journal of Sensor Science and Technology
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• v.11 no.6
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• pp.365-370
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• 2002

The jumping ring apparatus described in this study is used to demonstrate and educate the effects of electromagnetic induction. Placing an aluminum ring over the core and switching on AC source causes the ring to jump in the air due to induced currents in the ring producing a magnetic field opposed to that produced in the core. This force is a function of flux density, ac current of ring and levitated height of the ring. Using photo sensor arrays, detect the ring position and represent the position of the ring to analog voltage for an education performance. This paper presents modelling of the jumping ring system and shows how does control signal generate in order to follow desired position.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.107.2-107
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• 2001

We propose portable equipment that monitors a current and potential on high-potential power transmission lines. In the equipment, a current and voltage sensor are attached to a hollow insulator that supports a power transmission line: A current on a power line is detected by an air-core solenoidal coil clamped to the line and the detected current signal is transmitted to the ground station by using optical data link, A potential on a power transmission line is detected by a high resistance element, zinc oxide (ZnO) that acts as a potential divider between the power line and the ground. The equipment does not require high potential insulators and magnetic cores which. This leads to the following advantages of the equipment: (a) It is easily installed owing to its small size and its simple structure; (b) It operates in low ...

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.12
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• pp.2246-2253
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• 2011

This paper presents the error correction method of magnetic position sensor using recursive least square method (RLSM) with forgetting factor. Magnetic position sensor is proposed for linear position detection of the linear motor which has tooth shape stator, consists of permanent magnet, iron core and linear hall sensor, and generates sine and cosine waveforms according to the movement of the mover of the linear motor. From the output of magnetic position sensor, the position of the linear motor can be detected using arc-tan function. But the variation of the air gap between magnetic position sensor and the stator and the error in manufacturing process can cause the variation in offset, phase and amplitude of the generated waveforms when the linear motor moves. These variations in sine and cosine waveforms are changed according to the current linear motor position, and it is very difficult to compensate the errors using constant value. In this paper, the generated sine and cosine waveforms from the magnetic position sensor are compensated on-line using the RLSM with forgetting factor. And the speed observer is introduced to reduce the effect of uncompensated harmonic component. The approaches are verified by some simulations and experiments.

• Journal of the Korean Ceramic Society
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• v.41 no.2
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• pp.97-101
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• 2004

W $O_{x}$-based semiconductor type thin film gas sensor was fabricated for the detection of N $O_{x}$ by reactive d.c. sputtering method. The relative oxidation state of the deposited W $O_{x}$ films was approximately compared by the calculation of the difference of the binding energy between Ols to W4 $f_{7}$2/ core level XPS spectra in the standard W $O_3$ powder of known composition. As the annealing temperature increased from 500 to 80$0^{\circ}C$, relative oxygen contents and grain size of the sputtered films were gradually increased. As the results of sensitivity ( $R_{gas}$/ $R_{air}$) measurements for the 5 ppm N $O_2$ gas, the sensitivity was 110 and the sensor showed recovery time as fast as 200 s. The other sensor properties were examined in terms of surface microstructure, annealing temperature, and relative oxygen contents. These results indicated that the W $O_3$ thin film with well controlled structure is a good candidate for monitoring and controlling of automobile exhaust.haust.t.t.t.

• Current Optics and Photonics
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• v.3 no.6
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• pp.541-547
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• 2019

A novel photonic crystal fiber (PCF) sensor with three D-shaped holes based on surface plasmon resonance (SPR) is analyzed in this paper. Three D-shaped holes are filled with the analyte, and the gold film is deposited on the side of three planes. The design of D-shaped holes with outward expansion can effectively solve the uniformity problem of metallized nano-coating, it is beneficial to the filling of the analyte and is convenient for real-time measurement of the analyte. Compared with the hexagonal lattice structure, the triangular arrangement of the clad air holes can significantly reduce the transmission loss of light and improve the sensitivity of the sensor. The influences of the air hole diameter, the distance between D-shaped holes and core, and the counterclockwise rotation angle of D-shaped holes on sensing performance are studied. The simulation results show that the wavelength sensitivity of the designed sensor can be as high as 10100 nm/RIU and the resolution can reach 9.9 × 10^-6 RIU.

• Journal of the Korean Magnetics Society
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• v.25 no.3
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• pp.83-86
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• 2015

Nowadays the weapon systems are employed air bursting munition (ABM) as smart programmable 40 mm shells which have been developed in order to hit the target with programmed munition that can be air burst after a set distance in the battlefield. In order to improve the accuracy of such a bursting time, by measuring the speed of the munition from the barrel, weapon systems calculate the exact time of flight to the target and then the time information must be inputted to the munition. In this study, we introduce a device capable of detecting a shot at K4 40 mm automatic grenade. The shot is composed of a rotating copper band to convert linear motion into rotary motion when it passes through the barrel, the steel section is exert the effect of fragment and aluminum section to give fuze information. The aluminum section was used to detect munition using eddy current method. To measure muzzle velocity by means of non-contact method, two eddy current probes separated 10 cm was employed. Time interval between two eddy current probe detection times was used as muzzle velocity. The eddy current probe was fabricated U-shape Mn-Zn ferrite core with enamelled copper wire, and 200 kHz alternating current was used to detect inductance change. Measured muzzle velocity using the developed sensor was compared to the Doppler radar system. The difference was smaller than 1%.