• 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 Sensor Science and Technology
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• v.27 no.3
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• pp.186-191
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• 2018

Smart textile industries have been precipitously developed and extended to electronic textiles and wearable devices in recent years. In particular, owing to an increasingly aging society, the elderly healthcare field has been highlighted in the smart device industries, and pressure sensors can be utilized in various elderly healthcare products such as flooring, mattress, and vital-sign measuring devices. Furthermore, elderly healthcare products need to be more lightweight and flexible. To fulfill those needs, textile-based pressure sensors is considered to be an attractive solution. In this research, to apply a textile to the second layer using a pressure sensing device, a novel type of conductive textile was fabricated using vapor phase polymerization of poly(3,4-ethylenedioxythiophene) (PEDOT). Vapor phase polymerization is suitable for preparing the conductive textile because the reaction can be controlled simply under various conditions and does not need high-temperature processing. The morphology of the obtained PEDOT-conductive textile was observed through the Field Emission Scanning Electron Microscope (FESEM). Moreover, the resistance was measured using an ohmmeter and was confirmed to be adjustable to various resistance ranges depending on the concentration of the oxidant solution and polymerization conditions. A 3-layer 81-point multi-pressure sensor was fabricated using the PEDOT-conductive textile prepared herein. A 3D-viewer program was developed to evaluate the sensitivity and multi-pressure recognition of the textile-based multi-pressure sensor. Finally, we confirmed the possibility that PEDOT-conductive textiles could be utilized by pressure sensors.

• Journal of the Korean Society for Nondestructive Testing
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• v.35 no.2
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• pp.128-133
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• 2015

This paper describes the construction of a static 3D ultrasonography image by tracking the radiation beam position during the handy operation of a 1D array probe to enable point-of-care use. The theoretical model of the transformation from the translational and rotational information of the sensor mounted on the probe to the reference Cartesian coordinate system was given. The signal amplification and serial communication interface module was made using a commercially available sensor. A test phantom was also made using silicone putty in a donut shape. During the movement of the hand-held probe, B-mode movie and sensor signals were recorded. B-mode images were periodically selected from the movie, and the gray levels of the pixels for each image were converted to the gray levels of 3D voxels. 3D and 2D images of arbitrary cross-section of the B-mode type were also constructed from the voxel data, and agreed well with the shape of the test phantom.

• Journal of Sensor Science and Technology
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• v.25 no.6
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• pp.423-430
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• 2016

This study used a single metal oxide semiconductor (MOS) sensor to classify the major odorous gases hydrogen sulfide ($H_2S$), ammonia ($NH_3$) and toluene ($C_6H_5CH_3$). In order to classify these odorous substances, the voltage on the MOS sensor heater was gradually reduced in 0.5 V steps 5.0 V to examine the changes to the response by the cooling effect on the sensor as the voltage decreased. The hydrogen sulfide gas showed the highest sensitivity compared to odorless air under approximately 2.5 V and the ammonia and toluene gases showed the highest sensitivity under approximately 5.0 V. In other words, the hydrogen sulfide gas reacted better in the low temperature range of the MOS sensor, and the ammonia and toluene gases reacted better in the high-temperature range. In order to analyze the response characteristics of the MOS sensor by temperature in a pattern, a two-dimensional (2D) x-y pattern analysis was introduced to clearly classify the hydrogen sulfide, ammonia, and toluene gases. The hydrogen sulfide gas was identified by a straight line with a slope of 1.73, whereas the ammonia gas had a slope of 0.05 and the toluene gas had a slope of 0.52. Therefore, the 2D x-y pattern analysis is suggested as a new way to classify these odorous substances.

• Journal of Sensor Science and Technology
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• v.32 no.4
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• pp.232-237
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• 2023

This paper presents a system for estimating the position of a magnet using a magnetic sensor. An algorithm is presented to analyze the waveform and output voltage values of the magnetic field generated at each position when the magnet moves and to estimate the position of the magnet based on the analyzed data. Here, the magnet is sufficiently small to be inserted into a blood vessel and has a micro-magnetic field of hundreds of nanoteslas owing to the small size and shape of the guide wire. In this study, a highly sensitive magneto-impedance (MI) sensor was used to detect these micro-magnetic fields. Nine MI sensors were arranged in a 3×3 configuration to detect a magnetic field that changes according to the position of the magnet through the MI sensor, and the voltage value output was polynomially regressed to specify a position value for each voltage value. The accuracy was confirmed by comparing the actual position value with the estimated position value by expanding it from a 1D straight line to a 3D space. Additionally, we could estimate the position of the magnet within a 3% error.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.30 no.6
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• pp.975-980
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• 2020

To protect wireless sensor networks (WSNs), various key distribution and management schemes have been proposed. However, most of them conducted simulations and experiments for performance evaluation by considering only the two-dimensional (2D) environments. In this paper, we investigate the effect of real-world three-dimensional (3D) topographic features on the key pre-distribution schemes for WSNs. For this purpose, we analyze and compare the performance of three pairwise key pre-distribution schemes in 2D and 3D environments: full pairwise (FP), random pairwise (RP), and full and random pairwise (FRP) schemes. For the experiments, we employ a network simulator NS-3 and 3D graphic tools such as Blender and Unity. As a result, we confirm that there was a difference in the performance of each scheme according to the actual 3D terrain and that the location-based FRP that considers deployment errors, has the highest efficiency in many aspects.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.8
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• pp.65-72
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• 2004

For the burrs formed in machining are irregular and very sharp in shape, it is usually very difficult to measure burr accurately. It was proved that micro burr geometry can be measured imprecision by the Conoprobe sensor using conoscopic holography method. We developed 3D burr measurement system using this sensor. The system is composed of Conoprobe sensor, XY table, controller and 3D measurement program. Some measurements using the developed system are conducted for the burrs formed in micro drilling and piercing. Specific software fur burr measurement includes several function, calculation of burr volume, average burr height. Burs formed on a curved surface were compensated and measured successfully using the basic surface compensation function.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.951-954
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• 2003

Generally, for the burrs formed in machining are irregular and very sharp in shape, it is usually very difficult to measure burr accurately. But, it is proved that precision measurement for micro burr using the conoprobe sensor by conoscopic holography method is possible. We developed 3D burr measurement system using this sensor. The system is composed of Conoscopic laser Sensor, X-Y table, controller and 3D measurement program. Some measurements using the developed system are applied to burrs formed in micro drilling and piercing.

• Journal of the Korea Safety Management & Science
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• v.15 no.2
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• pp.55-61
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• 2013

For years, many studies have mainly been investigated in a complicated human motion analysis. Recently, many motion analysis equipments have been studied and developed. Therefore, the more complex human movement analyses are possible, we have enabled us to perform more and more complicated human movement analyses. A Three-dimensional(3D) motion analysis on of the several methods is a useful tool for analyzing the human motion analysis. The purpose of this study was to develop the 3D human motion analysis using a kalman filter algorithm and a gyro sensor. The algorithm and sensor were used to human motion analysis with high-speed motion capture. In this study, the developed system will be adapted to facilitate golf swing analysis. Using the developed system, golfers and coaches who do not have advanced biomechanical knowledge can easily be used to their golf swing analysis. Future study is necessary for more practical and efficient area such as other sports industries, 3D game industries, rehabilitation training, etc..

• Journal of the Korean Society for Precision Engineering
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• v.31 no.2
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• pp.149-156
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• 2014

Flexible tactile sensors can provide valuable feedback to intelligent robots about the environment. This is especially important when the robots, e.g., service robots, are sharing the workspace with human. This paper presents a flexible tactile sensor that was manufactured by direct writing technique, which is one of 3D printing method with multi-walled carbon nano-tubes. The signal processing system consists of two parts: analog circuits to amplify and filter the sensor output and digital signal processing algorithms to reduce undesired noise. Finally, experimental setup is implemented and evaluated to identify the characteristics of the flexible tactile sensor system. This paper showed that this type of sensors can detect the initiation and termination of contacts with appropriate signal processing.