• Journal of the Korean Society for Railway
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• v.9 no.2 s.33
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• pp.230-236
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• 2006

For a short-term measurement to reduce an accident on a railroad crossing, it is necessary to find out the weakness and problems of existing equipment in the railroad transportation system. The analysis of railroad crossing accidents shows that main causes of accidents (24.9%) are the careless driving including an engine problem, damage on the safety equipment, slide on the snow, and an engine stop on the railroad crossing. Therefore, it is required to install a sensor, or to make a crossing gate at the exist for detecting obstacles on a railroad to prevent collisions among trains. This paper suggests 'a panel sensor using the strain gauge' to make up the weaknesses of the sensing Dead Zone, which are caused by using a laser method, and to detect any small objects passing railroads in order to reduce the errors, which are occurred in the earth magnetic field for controlling Exit Slide Crossing Arm Detector. The device, suggested in this paper, is verified with detecting any small objects passing the railroad, with judging entry decision clearly, and with controlling passing gate and obstruction warnings/cautions obstacles at the same time, through an experimental test.

• Journal of Korea Multimedia Society
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• v.18 no.3
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• pp.401-407
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• 2015

In this paper, we propose the method to eliminate EMI (Electro-Magnetic Interference) in ELF (Extremely Low Frequency) band below 2 KHz for extending the gesture-recognition distance of smart TVs to more than 3m using electric potential sensor. First, we measure the electric field generated from the back panel of a TV and propose the effective arrangement of two sets of differential sensors as well as the shielding method using metal fiber. Also, we eliminate the PLN (Power Line Noise) and other noise generated from the TV and sensors as well as surrounding environments using filters. Using the proposed EMI eliminating methods, we evaluate displacement ratio on measured signals according to distance between sensors and a moving hand. Experiment results show that our proposed method can extend the hand-gesture sensing distance using EPS (Electric Potential Sensor) up to more than 3m, which is enough to satisfy applicability of EPS based remote control to Smart TVs.

• Journal of Sensor Science and Technology
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• v.14 no.4
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• pp.244-249
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• 2005

In this study, radiation sensor tips are fabricated for remote sensing of X or gamma ray with inorganic scintillators and plastic optical fiber. The visible range of light from the inorganic scintillator that is generated by radiation source is guided by the plastic optical fiber and is measured by optical detector and power-meter. Two kinds of sensor tips are designed and fabricated such as film type and powder type. Many kinds of inorganic scintillators are used to fabricate both sensor tips, and the different wavelength of emitting lights from them are measured to determine the optimal inorganic scintillator which has maximum light output. As a radiation source X-ray generator and Ir-192 are selected to test a performance of sensor tip. It is expected that the fiber-optic radiation sensor is widely used in nuclear industry and medical applications due to its special characteristics such as good flexibility, easy in processing, long lengths and no interference to electro magnetic field.

• Journal of Magnetics
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• v.19 no.2
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• pp.151-154
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• 2014

Recent years have seen an increasing range of planar Hall resistive (PHR) sensor applications in the field of magnetic sensing. This study describes a new application of the PHR sensor to monitor a current. Initially, thermal drift experiments of the PHR sensor are performed, to determine the accuracy of the PHR signal output. The results of the thermal drift experiments show that there is no considerable drift in the signals attained from 0.1, 0.5, 1 and 2 mA current. Consequently, the PHR sensor provides adequate accuracy of the signal output, to perform the current monitoring experiments. The performances of the PHR sensor with bilayer and trilayer structures are then tested. The minimum detectable currents of the PHR sensor using bilayer and trilayer structures are $0.51{\mu}A$ and 54 nA, respectively. Therefore, the PHR sensor having trilayer structure is the better choice to detect ultra low current of few tens nanoampere.

• Journal of the Korea Society of Computer and Information
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• v.13 no.7
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• pp.207-212
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• 2008

In EMC(electromagnetic compatibility) certification, the facilities and equipments have been considered as important qualification for registration of EMC certification business. In future, the certification environment is also supposed to be restricted Strictly. Many organizations have made on attempt to establish, certification environment as a international standard. Therefore, in order to enhance the competitive powers of domestic certification industry, a real-time system which can be measure automatically and remotely the temperature, humidity, illumination, CO/CO2, magnetic field, and human sensing is proposed in this paper. This system can also maintain the appropriate measurement environment by using USN (ubiquitous sensor network). The availabilities are confirmed through the experiment.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.3
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• pp.223-232
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• 2014

An inductive sensor system is proposed to detect the gear location and angular position of a geared shaft for automatic feeding of the shaft into the proper cutting position of the other end. The system consists of two set of coils, bridge circuit, signal condition circuit, and microprocessor. The coil sensors of the system measure changes of inductance along with the surface position of a geared shaft. The inductance changes are transformed to voltages by the bridge circuit, which are then conditioned and processed for the recognition of the gear. In order to incorporate with the experimental results with the sensor system, a finite element method (FEM) simulation for the magnetic field between the sensor and the shaft was carried out. The predicted results and the experiments revealed that the sensor system was appropriate for sensing the position of gear and the angular position of gear tooth of a geared shaft.

• Korean Journal of Remote Sensing
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• v.33 no.5_3
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• pp.855-866
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• 2017

Several research cases using remote sensing methods to analyze changes of storage and dynamics of groundwater aquifer were reviewed in this paper. The status of groundwater storage, in an area with regional scale, could be qualitatively inferred from geological feature, surface water altimetry and topography, distribution of vegetation, and difference between precipitation and evapotranspiration. These qualitative indicators could be measured by geological lineament analysis, airborne magnetic survey, DEM analysis, LAI and NDVI calculation, and surface energy balance modeling. It is certain that GRACE and InSAR have received remarkable attentions as direct utilization from satellite data for quantification of groundwater storage and dynamics. GRACE, composed of twin satellites having acceleration sensors, could detect global or regional microgravity changes and transform them into mass changes of water on surface and inside of the Earth. Numerous studies in terms of groundwater storage using GRACE sensor data were performed with several merits such that (1) there is no requirement of sensor data, (2) auxiliary data for quantification of groundwater can be entirely obtained from another satellite sensors, and (3) algorithms for processing measured data have continuously progressed from designated data management center. The limitations of GRACE for groundwater storage measurement could be defined as follows: (1) In an area with small scale, mass change quantification of groundwater might be inaccurate due to detection limit of the acceleration sensor, and (2) the results would be overestimated in case of combination between sensor and field survey data. InSAR can quantify the dynamic characteristics of aquifer by measuring vertical micro displacement, using linear proportional relation between groundwater head and vertical surface movement. However, InSAR data might now constrain their application to arid or semi-arid area whose land cover appear to be simple, and are hard to apply to the area with the anticipation of loss of coherence with surface. Development of GRACE and InSAR sensor data preprocessing algorithms optimized to topography, geology, and natural conditions of Korea should be prioritized to regionally quantify the mass change and dynamics of the groundwater resources of Korea.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.7
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• pp.95-102
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• 2016

Geomagnetic sensors are widely utilized for sensing heading direction of quadrotors. However, measurement from a geomagnetic sensor is easily corrupted by environmental magnetic field interference and roll/pitch directional motion. In this paper, a measurement method of a quadrotor heading direction is proposed for application to yaw attitude control. In order to eliminate roll/pitch directional motion effect, the geomagnetic sensor data is compensated using the roll/pitch angles measured for stabilization control. In addition, yaw-directional angular velocity data from a gyroscope sensor is fused with the geomagnetic sensor data using a complementary filter which is a simple and intuitive sensor fusion method. The proposed method is applied to experiments, and the results are presented to prove validity and effectiveness of the proposed method.

• Journal of the Korean Magnetics Society
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• v.23 no.3
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• pp.104-109
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• 2013

Clip-type pulsimeter equipped with Hall device and a minute permanent magnet as sensing the minute movement of a radial artery was developed. The clinical data of the 120 number of subject acquisited through the clip-type pulsimeter did treated with a typical statistical logistic regression analysis. The prediction algorithm for the replete pulse and vacuous pulse was studied. The reflective peak time and the notch peak time were major parameters to discern the replete pulse and vacuous pulse. The discrimination rate was 65%. It suggests that the logistic regression equations are possible to use the diagnosis index to predict and discern the oriental pulse wave.

• Journal of the Korean Society for Nondestructive Testing
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• v.21 no.5
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• pp.542-548
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• 2001

A robust, accurate, broad-band, alternating current sensor using fiber-optics is being developed as a part of optical over current protection relay system. The sensor uses the Faraday effect in optical fiber and polarimetric measurements tc sense electrical current. The current sensing coil consists of a length of twisted optical fiber and Faraday rotator mirror to suppress the linear birefringence effect. Due to its single-ended closed path structure, it can not only be easily installed to the target with great isolation from other fields in the vicinity, but the sensitivity can be increased by using multiple turns. This paper reports on the theoretical backgrounds of the sensor design and the preliminary experimental results.