• Journal of the Korean Institute of Intelligent Systems
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• v.11 no.2
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• pp.178-183
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• 2001

Welding is essential for the manufacture of a range of engineering components which may vary from very large structures such as ships and bridges to very complex structures such as aircraft engines, or miniature components for microelectronic applications. Especially, a domestic situation of the welding automation is still depend on the arc sensing system in comparison to the vision sensing system. Specially, the gap-detecting of workpiece using conventional arc sensor is proposed in this study. As a same principle, a welding current varies with the size of a welding gap. This study introduce to the fuzzy membership filter to cancel a high frequency noise of welding current, and ART2 which has the competitive learning network classifies the signal patterns the filtered welding signal. A welding current possesses a specific pattern according to the existence or the size of a welding gap. These specific patterns result in different classification in comparison with an occasion for no welding gap. The patterns in each case of 1mm, 2mm, 3mm and no welding gap are identified by the artificial neural network.

• International Journal of Korean Welding Society
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• v.2 no.1
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• pp.45-51
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• 2002

In the multi-pass welding of pressure vessels or ships, the mechanical touch sensor system is generally used together with a manipulator to measure the gap and depth of the narrow gap to perform seam tracking. Unfortunately, such mechanical touch sensors may commit measuring errors caused by the deterioration of the measuring device. An automation system of narrow gap multi-pass welding using a laser vision system which can track the seam line of narrow gap and which can control welding power has been developed. The joint profile of the narrow gap, with 250mm depth and 28mm width, can be captured by laser vision camera. The image is then processed for defining tracking positions of the torch during welding. Then, the real-time correction of lateral and vertical position of the torch can be done by the laser vision system. The adaptive control of welding conditions like welding currents and welding speeds, can also be performed by the laser vision system, which cannot be done by conventional mechanical touch systems. The developed automation system will be adopted to reduce the idle time of welders, which happens frequently in conventional long welding processes, and to improve the reliability of the weld quality as well.

• Journal of the Optical Society of Korea
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• v.19 no.6
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• pp.575-585
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• 2015

Magnetic field in magnetic bearings is the physical medium to realize magnetic levitation, the distribution of the magnetic field determines the operating performance of magnetic bearings. In this paper, a thin-slice Fiber Bragg Grating-Giant Magnetostrictive Material magnetic sensor used for the air gap of magnetic bearings was proposed and tested in the condition of dynamic magnetic field. The static property of the sensor was calibrated and a polynomial curve was fitted to describe the performance of the sensor. Measurement of dynamic magnetic field with different frequencies in magnetic bearings was implemented. Comparing with the finite element simulations, the results showed the DC component of the magnetic field was detected by the sensor and error was less than 5.87%.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2010.10a
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• pp.537-537
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• 2010

High precision sensing is very important in various technologies. Especially, it is more important when it were applied to nano/micro meter level's sensing like AFM, storage, etc. And capacitive sensing is widely used method. To improve the measurement efficiency, many signal conditioners were studied and one of them was surface acoustic wave (SAW) device. SAW device is very widely used as a high frequency bandwidth filter. Due to the reflective characteristic of high frequency, the response of SAW device contains both propagative and reflective signal at the external impedance. In this paper, we used SAW device as signal conditioner of capacitive sensor. And high precision gap measurement was executed using capacitive load. Reference signal was reflective SAW response and the magnitude at the center frequency of SAW device by the change of impedance was checked. Finally, the attainable gap resolution was determined.

• Journal of environmental and Sanitary engineering
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• v.15 no.2
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• pp.102-111
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• 2000

As IR-sensor for detecting pollution material, the iron silicide has a fit band gap, high physicochemical stability at high temperature and good acid resistance. The growing film was formed with the Fe-Si bond and the organic compound because plasma resolved the injected precursors into various active species. In the Raman scattering spectrum, the Fe-Si vibration mode showed at 250 {TEX}$cm^{-1}${/TEX}. The FT-IR peak indicated that the various organic compounds were deposited on the films. The iron silicide was epitaxially grown to β-phase by the high energy of plasma. The lattice structure of films had [220]/[202] and [115]. The thickness of the films increased with the flow rate of silane. But rf-power increased with decreasing the thickness. The optical gap energy and the band gap were shown about 3.8 eV and 1.182∼1.194 eV. The band gap linearly increased and the formula was below: {TEX}$E_g^{dir}${/TEX}= 8.611×{TEX}$10^{-3}N_{D}${/TEX}＋1.1775

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.235-238
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• 2009

To study the relationship between spark ignition and the gap in the nano-scale region, the electric potential was applied to between a Pt-Ir tip and a gold substrate. The tip was sharpened by electro-chemical etching process in the solution of $CaCl_2;H_2O$ and acetone. The radius of tip was measured to be around 200nm and attached to the scanning probe microscope to control the gap between the tip and the substrate. The electric potential of 10V to 80V was applied to initialize the spark. The gaps and the current profile were measured to analyze the characteristics of spark ignition. A spark sustaining time was measured to be between 50ns and 200ns depending on the applied electric potential and the gap between the electrodes. The continuous electric discharge was successfully sustained up to 1 second of spark or arc time. The developed process can be applicable to the micro-scale fabrication of automotive sensors as a similar concept of GTAW.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.53.5-53
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• 2001

In continuous galvanizing process at steel making plant, coating weight on the surface of strip that pass through air knife is controlled by the pressure at the chamber of air knife and the gap between the nozzle of air knife and strip. The pressure can be easily measured and controlled. But it is difficult to measure the distance between Air knife nozzle and strip, and also difficult to decide how much distance air knife move. Because, the gap between nozzle and strip varies with the height of air knife, intermesh of stabilizing roll and welding of strips that have different thickness. In this research, we developed a gap sensor that can measure the relative distance between Air knife nozzle and strip. And several tests are performed to find optimal condition for application at real plant. We performed test in which the possibility of the sensor to apply ...

• Journal of the Korean Society for Precision Engineering
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• v.26 no.4
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• pp.107-113
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• 2009

In this paper, we studied of measurement the vibration of natural frequency using optical fiber sensor. The boring bar for measurement of vibration in use optical fiber sensor has the advantage of direct measure for the frequency than accelerometer. Because it deal with output value on electrical signal of optical fiber in physical disturbance when it measures the frequency of vibration. The optical fiber sensor measured the vibration of boring bar by the gap in sensing jig while optical fiber just kept contact with boring bar. A prototype system was composed of jig part with gap and optical system part. In this paper, we found out the possibility to measurement of vibration by the gap in use optical fiber.

• Journal of KIISE:Information Networking
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• v.35 no.3
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• pp.192-206
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• 2008

Multihop is the main communication style for wireless sensor networks composed of tiny sensor nodes. Until now, most applications have treated the periodic small sized sensing data. Recently, the burst traffic with the transient and continuous nature is increasingly introduced due to the advent of wireless multimedia sensor networks. Therefore, the efficient communication protocol to support this trend is required. In this paper, we propose a novel PIGAB(Packet Interval Gap based on Adaptive Backoff) protocol to efficiently transmit the burst data in multihop wireless sensor networks. The contention-based PIGAB protocol consists of the PIG(Packet Interval Gap) control algorithm in the source node and the MF(MAC-level Forwarding) algorithm in the relay node. The PIGAB is on basis of the newly proposed AB(Adaptive Backoff), CAB(Collision Avoidance Backoff), and UB(Uniform Backoff). These innovative algorithms and schemes can achieve the performance of network by adjusting the gap of every packet interval, recognizing the packet transmission of the hidden node. Through the simulations and experiments, we identify that the proposed PIGAB protocol considerably has the stable throughput and low latency in transmitting the burst data in multihop wireless sensor networks.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.9
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• pp.589-595
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• 2017

MOS-FET structured gas sensors were manufactured using MWCNTs for application as NOx gas sensors. As the gas sensors need to be heated to facilitate desorption of the gas molecules, heat dispersion plays a key role in boosting the degree of uniformity of molecular desorption. We report the desorption of gas molecules from the sensor at $150^{\circ}C$ for different sensor electrode gaps (30, 60, and $90{\mu}m$). The COMSOL analysis program was used to verify the process of heat dispersion. For heat analysis, structure of FET gas sensor modeling was proceeded. In addition, a property value of the material was used for two-dimensional modeling. To ascertain the degree of heat dispersion by FEM, the governing equations were presented as partial differential equations. The heat analysis revealed that although a large electrode gap is advantageous for effective gas adsorption, consideration of the heat dispersion gradient indicated that the optimal electrode gap for the sensor is $60{\mu}m$.