• Journal of the Korean Society for Railway
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• v.13 no.5
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• pp.488-492
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• 2010

In order to verify the performance of high-speed train and core equipments such as current collection system, sophisticated tests and evaluating procedures must be considered. In case of force sensor to test contact force of pantograph, it should customize the test instruments according to characteristics of pantograph. In this paper, the force sensor with a built-in strain-gauge which developed to improve measuring performance of contact force between the pantograph and catenary system is introduced. The test and evaluation results of force sensor's static and dynamic calibration with pantograph shows that its design is very suitable and applicable for on-line test. Henceforth, the force sensor will be applied to test interaction characteristics between the pantograph and catenary system on the high-speed line and expected by a part of measuring system for evaluating current collecting characteristics more reliably.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.6
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• pp.68-73
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• 2009

One of the traditional optical methods to monitor a tool is a CCD sensor-based vision system which captures an aspect of the tool in real time. In the case using the CCD sensor, specific lens-modules are necessary to monitor the tool with higher resolution than its pixel size, and a microprocessor is required to attain desired data from captured images. Thus theses additional devices make the entire measurement system complex. Another method is to use a pair of an optical source and a detector per measuring axis. Since the method is based on the intensity modulation, the structure of the measurement system is simper than the CCD sensor-based vision system. However, in the case measuring the three dimensional position of the tool, it is difficult to apply to micro machine-tools because there may not be space to integrate three pairs of an optical source and a detector. In this paper, in order to develop a tool-origin measurement system which is employed in micro machine-tools, the improved method to measure a tool origin in x, y and z axes is introduced. The method is based on the intensity modulation and employs one pair of an optical source radiating divergent beams and a quadrant photodiode to detect a three dimensional position of the tool. This paper presents the measurement models of the proposed tool-origin sensor. The models were verified experimentally The verification results show that the proposed method is possible and the induced models are available for design.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.4
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• pp.26-32
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• 2020

Recently, as various wearable devices and IoT technologies have emerged and been applied to real applications, various sensors have been developed to satisfy their purposes and applied. In even In medical applications, IoT technologies have been applied gradually, and particularly, magnets and magnetic sensors have already been playing an important role in the medical industry. In wrist rehabilitation, this kind of sensor technology has enabled us to easily and conveniently measure wrist movement and gestures because there are no tangled lines required between the magnet and sensor. However, one of the drawbacks is that nonlinear output is generated because of the characteristics of a magnetic field. Also, the movement of the wrist joint involves small bones, and so it is not easy to simply model the movement. In order to resolve these issues and accurately measure sensor data, a calibration procedure is inevitable in the measurement. Thus, this paper proposes a practical model and simple calibration methods for measuring the distance between a magnet and a magnetic sensor.

• Journal of Sensor Science and Technology
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• v.25 no.1
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• pp.57-64
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• 2016

To understand a two-phase flow, a liquid film thickness is one of the important factors. A lot of researches have been performed to measure liquid film thickness with various approaches. Recently, an electrical conductance method which uses the conductivity of the liquid film has been widely applied on measuring the liquid film thickness. Though the electrical method has an advantage in high spatial resolution, as the conductivity of liquid can be affected by its temperature variation, the conventional electrical conductance methods have a limitation in being applied on varying temperature conditions where a heat transfer is involved. The purpose of this study is to develop a three-ring liquid film sensor that overcomes the limitation of the conventional method. The three-ring conductance method can measure the film thickness regardless of temperature variation by compensating the change of liquid conductivity. Considering its application on a wide range of conditions such as high temperature or curved surfaces, the sensor was fabricated on flexible printed circuit board (FPCB) in this study. This paper presents the concept of the measurement method, design procedure, prototype sensor fabrication and calibration results.

• Journal of Ocean Engineering and Technology
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• v.36 no.3
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• pp.153-160
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• 2022

Moored floating platforms have great potential in ocean engineering applications because a mooring system is necessary to keep the platform in station, which is directly related to the operational efficiency and safety of the platform. This paper briefly introduces the technical and operational details of an optical sensor for measuring the tension of mooring lines of a moored platform in waves. In order to check the performance of optical sensors, an experiment with a moored floating platform in waves is carried out in the wave tank at Changwon National University. The experiment is performed in regular waves and irregular waves with a semi-submersible and triangle platform. The performance of the optical sensor is confirmed by comparing the results of the tension of the mooring lines by the optical sensor and tension gauges. The maximum tension of the mooring lines is estimated to investigate the mooring dynamics due to the effect of the wave direction and wavelength in the regular waves. The significant value of the tension of mooring lines in various wave directions is estimated in the case of irregular waves. The results show that the optical sensor is effective in measuring the tension of the mooring lines.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1991.11a
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• pp.80-86
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• 1991

In this study an the development of the heat flux sensor with thermocouple, the heat-treated adhesive type film nickel gauge(Ni-Gauge) for measuring temperature was used. and this Ni-Gauge is not only comparable for platinum gauge(Pt-Gauge) in linearity, but also economically cheap. And from this viewpoint. numerical analysis is essential to investigate charateristics of sensor, since this analysis is capable of simulating precise boudary condition and practical conditions and so on. By the way. there are many types of heat flux sensor. of which adhesive type flux sensor is common, in the study this type of heat flux sensor was chogen. and analysis of the sensor is considered as a kind of open cavity figure. performed by SIMPLER algorithm. As a result. through temperature distributial of the sensor by numerical analysis in steady and unsteady state, the dracteristics of the acdhesive type heat flux sensor(lst heat flux sensor) acooodinge to heat flux, that is, outvoltage, sensitivity. and responsibilty could be evaluated. in addition, time of improved heat flux sensor(2nd heat flux sensor) could be predicted fran the reflectian of proper operating temperature(l50 $^{\circ}C$)of theNi-Gauge.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.7
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• pp.524-529
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• 2016

We describe the design and fabrication of a two-axis force/torque sensor with parallel-plate beams (PPBs) and single beams for measuring force and torque in hip-joint rehabilitation exercise using a lower rehabilitation robot. The two-axis force/torque sensor is composed of an Fz force sensor and a Tz torque sensor, which detect z direction force and z direction torque, respectively. The two-axis force/torque sensor was designed using the FEM (Finite Element Method) and manufactured using strain gages. The characteristics experiment of the two-axis force/torque sensor was carried out. The test results show that the interference error of the two-axis force/torque sensor was less than 0.64% and the repeatability error and the non-linearity of the two-axis force/torque sensor were less than 0.03%. It is thought that the developed two-axis force/torque sensor could be used for a lower rehabilitation robot.

• Smart Structures and Systems
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• v.6 no.5_6
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• pp.689-709
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• 2010

In this paper, a low cost, low power but multifunctional wireless sensor node is presented for the impedance-based SHM using piezoelectric sensors. Firstly, a miniaturized impedance measuring chip device is utilized for low cost and low power structural excitation/sensing. Then, structural damage detection/sensor self-diagnosis algorithms are embedded on the on-board microcontroller. This sensor node uses the power harvested from the solar energy to measure and analyze the impedance data. Simultaneously it monitors temperature on the structure near the piezoelectric sensor and battery power consumption. The wireless sensor node is based on the TinyOS platform for operation, and users can take MATLAB$^{(R)}$ interface for the control of the sensor node through serial communication. In order to validate the performance of this multifunctional wireless impedance sensor node, a series of experimental studies have been carried out for detecting loose bolts and crack damages on lab-scale steel structural members as well as on real steel bridge and building structures. It has been found that the proposed sensor nodes can be effectively used for local wireless health monitoring of structural components and for constructing a low-cost and multifunctional SHM system as "place and forget" wireless sensors.

• Tribology and Lubricants
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• v.40 no.4
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• pp.139-143
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• 2024

This study evaluates the sensitivity of a ferrous particle sensor in response to changes in viscosity in a gearbox. Composed of various gears, the gearbox typically occurs significant ferrous wear due to gear contact. Condition monitoring is primarily implemented by measuring the number of ferrous wear particles in the lubricant. Gearboxes are critical in many systems, including wind turbines, for facilitating changes in speed and torque. Therefore, technology to monitor ferrous particles in gearboxes is essential. In this study, a simplified gearbox is numerically modeled to assess sensor sensitivity based on viscosity and sensor position. Three sensor positions are considered: one directly beneath the gear and two at locations farther from the gear. Analyses are conducted using lubricants with low viscosity and gear oil. Sensor sensitivity is defined by the number of ferrous particles adhering to the sensor, where more particles indicated higher sensitivity. The evaluation reveals that the position directly beneath the gear exhibits the highest sensitivity due to direct influence from the main flow. To achieve optimal sensitivity, sensors should be installed in the main flow path as determined by flow analysis. Evaluation of sensor sensitivity with changes in viscosity shows that a higher viscosity results in a lower sensor sensitivity. Therefore, for ease of analysis, performing an analysis under low-viscosity conditions is useful for understanding the main flow and for identifying the optimal location for proper sensor position.

• Science of Emotion and Sensibility
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• v.25 no.3
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• pp.77-90
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• 2022

This study seeks to develop a stretch sensor for measuring the wrist movements of people using fishing lures. In order to confirm wrist movement, a stretch sensor was attached to the wrist band, and measurements of the dorsiflexion, plantar flexion, and fishing landing motion were measured using a scale to gauge factor, tensile strength, and elongation recovery rate. A conductive sensor using CNT dispersion was developed and applied to the E-band under the same conditions. A total of 15 sensors of the same size and five types of impregnation once, twice, and three times each were used to measure the gauge factor using UTM. The sensor that was impregnated twice had the best gauge rate, and the prototypes were manufactured with three sensors with high gauge rates and tensile strength. The results of the operation test conducted by connecting to the Arduino showed that Sample 1, which had the highest tensile strength and gauge factor, had a stable graph wavelength in three operations. Samples 2 and 3 showed stable wavelengths in the dorsiflexion and the plantar flexion; however, signal noise appeared in the fishing landing motion. This showed stable wavelengths in the two motions, but the wavelengths of the graphs differ depending on the tensile strength and gauge factor in the fishing landing motion. As a result, it was possible to identify the conditions necessary for manufacturing a stretch sensor for measuring wrist movement. This study will contribute to the development of smart wearable products for lure fishing.