• Journal of Sensor Science and Technology
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• v.9 no.6
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• pp.396-403
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• 2000

The low- frequency acoustic sensor using the recently developed FBG has an excellent merits which the existing fiber-optic sensor has and also it has an excellent signal sensing effect in the environment of low-frequency($30Hz{\sim}300Hz$). Furthermore, we can expect the utilization of low-frequency signal defection instead of existing microphones in the environment of electric noise and also it can be developed as the high-sensibility multiplexing through the sensor array system.

• Smart Structures and Systems
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• v.16 no.3
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• pp.537-554
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• 2015

Magneto-electro-elastic (MEE) materials under thermal environment exhibits pyroelectric and pyromagnetic coefficients resulting in pyroeffects such as pyroelectric and pyromagnetic. The pyroeffects on the behavior of multiphase MEE sensor bonded on top surface of a mild steel cylindrical shell under thermal environment is presented in this paper. The study aims to investigate how samples having different volume fractions of the multiphase MEE sensor behave due to pyroeffects using semi-analytical finite element method. This is studied at an optimal location on a mild steel cylindrical shell, where the maximum electric and magnetic potentials are induced due to these pyroeffects under different boundary conditions. It is assumed that sensor and shell is perfectively bonded to each other. The maximum pyroeffects on electric and magnetic potentials are observed when volume fraction is $v_f$ = 0.2. Additionally, the boundary conditions significantly influence the pyroeffects on electric and magnetic potentials.

• KEPCO Journal on Electric Power and Energy
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• v.6 no.3
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• pp.323-324
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• 2020

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.10
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• pp.37-42
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• 2014

This paper discusses study of sensorless control of a variable speed switched reluctance motor (SRM) for electric AC compressors on electrical vehicles. A typical SRM drive requires a position sensor such as an encoder or hall sensor to measure the angular rotor position. However, harsh environment in electrical AC compressors for electric vehicles makes it difficult to use the position sensor in their motor drive system. Therefore, a sensorless control scheme for electric compressor motors utilizing magnetic characteristics of SRM with respect to position angle and phase current is proposed. The overall variable speed SRM drive with position sensorless control scheme has been modeled using Matlab/Simulink software and closed loop current control simulation is presented to validate the proposed sensorless drive control.

• Journal of the Optical Society of Korea
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• v.18 no.6
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• pp.739-745
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• 2014

We have demonstrated a $Ti:LiNbO_3$ electro-optic electric-field sensor utilizing a $1{\times}2$ Y-fed balanced-bridge Mach-Zehnder interferometric (YBB-MZI) modulator, which uses a 3-dB directional coupler at the output and has two complementary output waveguides. A dc switching voltage of ~25 V and an extinction ratio of ~12.5 dB are observed at a wavelength of $1.3{\mu}m$. For a 20 dBm rf input power, the minimum detectable electric fields are ~8.21, 7.24, and ~13.3 V/m, corresponding to dynamic ranges of ~10, ~12, and ~7 dB at frequencies of 10, 30, and 50 MHz respectively. The sensors exhibit almost linear response for an applied electric-field intensity from 0.29 V/m to 29.8 V/m.

• Journal of the Korean Society for Railway
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• v.8 no.3
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• pp.216-221
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• 2005

In electric motor coaches, the rolling stocks move by the adhesive effort between rail and driving wheel. Generally, the adhesive effort is defined by the function of both the wright of electric motor coach and the adhesive effort between rails and driving wheel. The characteristics of adhesive effort is strongly affected by the conditions between rails and driving wheel. When the adhesive effort decreases suddenly, the electric motor coach has slip phenomena. This paper proposes a re-adhesion control based on disturbance observer and sensor-less vector control. The numerical simulation and experimental results point out that the proposed re-adhesion control system has the desired driving wheel torque response for the tested bogie system of electric coach. Based on this estimated adhesive effort, the re-adhesion control is performed to obtain the maximum transfer of the tractive effort.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.1
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• pp.239-243
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• 2012

This paper proposes a electric resistor sensor to measure soil moisture. The soil moisture sensor uses resistance to measure the water content of soil. The main idea is the resistance between the sensor probes can vary according to the water content of soil. Then the resistance difference can be converted to the electrical signal. This sensor is very simple and cheap. In this paper several sensors are connected in serial and composed a sensor network. This sensor network is adopted in IMS(Internet Management System) and demonstrated.

• Korean Journal of Optics and Photonics
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• v.8 no.2
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• pp.161-164
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• 1997

A new hybrid, heterodyne, fiber-optic electric field sensor scheme is presented. In this scheme, a dual polarization, dual frequency, stabilized He-Ne laser is used for the light source of the interferometer, Probe beam is delivered to the sensor head using polarization maintaining fiber. In the sensor head, $LiTaO_3$ electro-optic crystal is used for sensing element. Phase retardation is induced on the dual frquency, dual polarization probe beam due to applied electric field across the crystal. Induced phase retardation is demodulated by in-phase and quadrature demodulation technique. In this way, we can obtain optimum sensitivity for electric field measurement regardless a quasi-static phase difference between two polarization components.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.264-266
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• 2005

Recently, on-line diagnosis methods through wired and wireless networks are widely adopted in the diagnosis of industrial Electric Facilities, such as generators, transformers and motors. Also smart sensors which includes sensors, signal conditioning circuits and micro-controller in one board are widely studied in the field of condition monitoring. This paper suggests an self-powered system suitable for condition-monitoring smart sensors, which uses parasitic vibrations of the facilities as energy source. First, vibration-driven noise patterns of the electric facilities are presented. And then, an electromagnetic generator which uses mechanical mass-spring vibration resonance are suggested and designed. Finally energy consumption of the presented smart sensor, which consists of MEMS vibration sensors, signal conditioning circuits, a low-power consumption micro-controller, and a ZIGBEE wireless tranceiver, are presented. The usefulness and limits of the presented electromagnetic generators in the field of electric facility monitoring are also suggested.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.7
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• pp.562-569
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• 2016

This paper proposes a navigation system with a robust localization method for an underwater unmanned vehicle. For robust localization with IMU (Inertial Measurement Unit), a DVL (Doppler Velocity Log), and depth sensors, the EKF (Extended Kalman Filter) has been utilized to fuse multiple nonlinear data. Note that the GPS (Global Positioning System), which can obtain the absolute coordinates of the vehicle, cannot be used in the water. Additionally, the DVL has been used for measuring the relative velocity of the underwater vehicle. The DVL sensor measures the velocity of an object by using Doppler effects, which cause sound frequency changes from the relative velocity between a sound source and an observer. When the vehicle is moving, the motion trajectory to a target position can be recorded by the sensors attached to the vehicle. The performance of the proposed navigation system has been verified through real experiments in which an underwater unmanned vehicle reached a target position by using an IMU as a primary sensor and a DVL as the secondary sensor.