• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.427-427
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• 2021

During the rainy season, heavy downpours are always a source of concern for the world. Flooding and heavy rains can devastate communities, disrupt agriculture, and contribute to traffic accidents.. Weir and flow hall effect sensors are the conventional analytical methods for measuring flow rate; in this paper, we analyzed manhole flowrate statistics. The measurement of the flow rate of a notch/weir is a time-consuming task that necessitates continuous mathematical analysis. . We created three types of IoT sensors in this study: (HC-SR04 ultrasonic, YF-S201 magnetic, and HB100 radar), which take the sensor's real-time input signal and estimate the flow using a notch equation and a previously calibrated optimized coefficient of discharge. The proposed systems are cost-effective, but in terms of accuracy, we found that the HC-SR04 ultrasonic sensor is the best of the three systems

• Journal of Sensor Science and Technology
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• v.8 no.2
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• pp.184-188
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• 1999

PbTe thin films of high quality were deposited on HF-treated Si(100) substrates at various substrate temperature by pulsed laser deposition technique. XRD patterns showed that PbTe layers were well-crystallized to a cubic phase with (h00) preferred orientation with the substrate temperature up to $300^{\circ}C$. PbTe films could not form at substrate temperature above $400^{\circ}C$ because of reevaporation of the Pb. According to AFM image, the surface of films was composed of small granular crystals and flat matrix. According to the increase of substrate temperature, the grain size at film surface becomes larger. By Hall-effect measurement, the carrier concentration and Hall mobility of n-type PbTe films grown by $T_{sub}=300^{\circ}C$ were $3.68{\times}10^{18}cm^{-3}$ and $148\;cm^2/Vs$, respectively.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.276-280
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• 1993

An articulated, multifinger mechanical hand can carry out grasping and manipulation operations on objects of different type and shape. In this paper the architecture of the mechanical hand is presented. Joints are driven by two antagonist tendons. Strain gauges are used to derive tendon tensions, and located in the palm of the hand. Angular defection of the joints is measured by Hall effect sensors attached to the joints. A multiprocessor-based architecture for controlling the hand is illustrated.

• Journal of Mechanical Science and Technology
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• v.17 no.12
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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.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10a
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• pp.706-710
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• 1988

Using back electro-motive force(EMF) signals of a brushless DC motor, the sensorless micro-processor controlled drive system was developed. In this new commutation method, the manual pulses are used for relatively short accelerating phase and then the exact commutational positions are detected based upon the back emf signals. The hardware and software implementations with the experiment to compare the performance of the developed system with the, conventional system using hall effect sensors are included. By reducing the number of the required sensors in the artificial heart control system, the total reliability will be incresed.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.5
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• pp.50-56
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• 2015

As rotor position is a reference of coordinate in vector control of PMSM, the information of exact rotor position is required. To measure the position of motors, hall-effect sensors, encoders, resolvers, etc. are used. Among these sensors, resolvers have good endurance in the variation of circumstance and can be used in a wide range of temperature, but resolvers are less exact than encoders. In addition, resolvers have a drawback that the output signal contains periodic error components. Thus, this paper proposes a compensation method for the unique position error in resolvers using Kalman filter to achieve high performance control of PMSM. The validity of the proposed scheme is demonstrated through simulation studies.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.1018-1021
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• 2003

This dissertation is reference to measure visual information about the configuration of magnetic field automatically and materialize the new magnetic field mapping system for the rapid and clear measure by using of the mediocrity orthogonal robot in the three- dimensional space required the measure of magnetic field concurrently. The measuring sensor is composed to be available for the measure of three-dimensional direction of magnetic field by vertically conjoining each of three hall sensors utilized of the hall effect and installed Gaussmeter, which is devised to receive the sensor result and the robot controller, away from the measuring robot in order to minimize the affection of magnetic field. Also, the controller and Gaussmeter are composed of Use interface, RS-232C and IEEE-488.2 communication. Interface system is written in NI's LabVIEW and composed to be able to set up a measuring area, the measuring number of times, two and three-dimensional graph, the velocity of robot and the magnetic field distribution graph of each element by inputting parameters. The materialized magnetic field mapping system expert the collection of the data easily and the effect of utilizing data.

• Journal of the Korean Institute of Gas
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• v.6 no.1 s.17
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• pp.10-16
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• 2002

This paper introduces developed prototype intelligent pig which detects corrosion on pipeline by using Magnetic Flux Leakage technology. The 8 inch developed MFL(Magnetic Flux Leakage) pig is composed of 5 yokes which magnetize pipeline wall and 45 Hall sensors which detect MFL signal. The designed MFL modules are analyzed by using magnetic circuit method in order to confirm whether pipeline wall is fully saturated. A variety of artificial defects are manufactured on 8 inch diameter steel pipeline in order to acquire MFL signals. So leakage flux of the axial, radial and circumferential component was acquired as defects. The results of this paper show that design technique for 8 inch MFL pig can be applied to large diameter MFL pig and 0.5mm defect depth can be detected.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.12
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• pp.8306-8313
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• 2015

Open-type current sensors have been commonly used for DC motor controller, AC variable controller and Uninterruptible Power Supply. Recently they have begun to be used more widely, as the growth of renewable energy and smart-grid in power system. Considering most of the open-type current sensors are imported, developing the core technology needed to produce open-type current sensors is required. This paper describes the development and test results of open-type current sensors. Design of C type magnetic core, selection and test of a Hall sensor, design of current source circuit and signal conditioning circuit are described. 100A class DIP(Dual In-line Package) type and SMD(Surface Mount Devide) type open-type current sensors was made and tested. Test results show that the developed open-type current sensor satisfies the accuracy requirement of 2% and linearity requirement of 2% at 100 A of DC and AC current of 60Hz. Temperature compensation was carried out by using a temperature compensation circuit with NTC(Negative Temperature Coefficient) thermistor and the effect of the temperature compensation are described.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.362-362
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• 2012

Graphene-based materials have been gaining the unprecedented academic and industrial applications, due to the unique charge transport as a new kind of 2-dimensional materials. The applications incorporate electronic devices, nonvolatile memories, batteries, chemical sensors, etc. based on the electrical, mechanical, structural, optical, and chemical features newly reported. The current work employs thermal chemical vapor deposition involving H2 and CH4, in order to synthesize the 2-dimensional graphene materials. The qualitative/quantitative characterizations of the synthesized graphene materials are evaluated using Raman spectroscopy and Hall Measurements, In particular, the effect of processing variables is systematically investigated on the formation of graphene materials through statistical design of experiments. The optimized graphene materials will be attempted towards the potential applications to flat-panel displays.