• 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.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1996-1998
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• 2000

In this paper, the electric and magnetic field waveforms produced by cloud-to-groud lightning discharges were measured and statistically analyzed. The measuring system used to measure the electric and magnetic fields is consisted of the hemisphere electric field sensor, the loop magnetic field sensor and the data acquisition system. The stepped leader is appeared before the return stroke. Some parameters of the electric and magnetic fields produced by the stooped leaders in cloud-to-ground lightning discharges were investigated.

• Composites Research
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• v.27 no.4
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• pp.146-151
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• 2014

In this study, the experimental study has been performed by varying the polarization of the electric field and impact force to check the piezoelectric characteristics of piezoelectric paint sensor. Piezoelectric paint sensor used in this study is composed of epoxy resin with a hardener and PNN-PZT powder in 1:1 weight ratio. The dimensions of the paint sensor specimen are $40{\times}40{\times}1mm^3$ and regular specimens were made using a mold. The voids are removed from the specimen in the vacuum desiccator. Both upper side and bottom side of the paint sensor were coated with silver paste for making an electrode and then dried at room temperature for a day. The poling treatment has been carried out under controlled conditions of the electric field in order to check the effect of piezoelectric sensitivities, while the poling temperature was fixed at room temperature and the poling time was set to 30 min. The piezoelectric sensitivities have been measured by comparing output voltage from paint sensor with output force from impact hammer when the impact hammer hits the paint sensor. In result, the effect of the electric field has been evaluated for the sensitivity and describe the result.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.1
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• pp.31-36
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• 2015

In this paper, an LED lighting system that is capable of automatic or maunal dimming control using a ultrasonic sensor and Bluetooth wireless communication technology is presented. The LED lighting system consists of a ultrasonic sensor, microcontroller unit, Bluetooth wireless communication, LED driver, and LED light source. By using the implemented LED lighting system sample, it is shown that the automatic and manual dimming control is realized. By using the ultrasonic sensor, the LED lighting is automatically brighter or dimmer depending on the distance between the sensor and an object. When using a smartphone that includes Bluetooth wireless communication function, one can not only manually control the brightness of the LED lighting from level 1 to 10, but also monitor the distance between the sensor and object on the smartphone.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.4
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• pp.244-249
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• 2014

In this research, it have developed a sensor that could diagnose inner deterioration of covered wires. With this sensor it observed results from simulation, and the attribute required for realization. For simulation it have used FLUX, it have considered all of geometric and electromagnetic information from coil and base metal that influences eddy current sensor's property in order to predict the final result. It assumed there is no mutual inductance in the coil with N number of turns, because equivalent current flows in coil that is continuously connected in eddy current sensor. It assumed circular coil loop draws a circle, always have self inductance, and they are connected in series and overlapped according number of turns (N) in coil, and bobbin configuration. Actual sensor was produced with consideration of inductance and number of turns (N). In conclusion, it were able to test the dependency through results from simulation, actual measurement, and modeling of simulation. It is considered that attributes of respective base metal and structure can be predicted by simulating in advance.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.2
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• pp.1-7
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• 2015

The Light Emitting Diode(LED) lighting control system proposed in this thesis is made up of a sensor module, a microcontroller, Bluetooth wireless communication, LED Driver, and LED downlight. The sensor module, comprised of an infrared sensor, an illumination sensor, and a temperature sensor, was designed to one Printed Circuit board(PCB). The system is able to identify the environment information collected by the sensor, and make it possible to control lighting automatically and manually through sensors. In addition, depending on users' conditions, a color temperature can be controlled. CS-1000, a spectroradiometer, was employed to measure the changing values of a color temperature in 8 steps. According to a test, it was found that it was possible to change a color temperature from 3187K of Warm White LED to 5598K of Cool White LED. The Bluetooth based wireless communication technique makes it possible to control more lighting devices than other wireless communication techniques does.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.4
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• pp.363-370
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• 2020

This paper reports the results of an experimental study using the BOTDR sensor to detect the unbonded location of attached CFRP sheet for structural rehabilitation. A specimens with the unattached CFRP sheet were fabricated for this study, on which BOTDR sensor was attached with a nylon net. During the flexural test of the specimens, the strain of the CFRP sheet was measured using the BOTDR sensor and electric resistance gauges. From the results, it was confirmed that the strain distribution obtained through the BOTDR sensor can be effectively used to visualize and detect the unbonded position of the CFRP sheet. In addition, In addition, the strain measured by the BOTDR sensor was found to be more effective in analyzing the overall structure behavior than the electric resistance strain gauge. The development of a BOTDR sensor with a measuring longth of less than 100 mm will enable accurate detection of the local unbonded position of the CFRP sheet.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.4
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• pp.1272-1277
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• 2010

Target detection and tracking wireless sensor network must have various signal processing ability. Wireless sensor nodes need to light weight signal processing algorithm because of energy constraints and communication bandwidth constraints. General signal processing algorithm of wireless sensor node consists of de-noising, received signal strength computation, feature extraction and signal compression. Wireless sensor network life-time and performance of target detection and classification depend on sensor node signal processing. In this paper, we propose energy efficient signal processing algorithm using wavelet transform. The proposed method estimates exact target position.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.2050-2051
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• 2007

As a fundamental investigation to develop a sensor which is able to detect shorted turn phenomenon of generator rotor, we have experimented with self-made sensor using flux generator and high-resolution oscilloscope. We have recorded sensor-induced voltage according to the different condition, such as variations of turn, diameter and length of sensor. Based on the acquired data, we analyzed and simulated under similar circumstances of actual spot to maximize reliability. We have a plan to invest more resources to supply power plants with the developed sensor for ourselves.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.597-599
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• 2005

To make the autonomous mobile robot move in the unknown space, we have to know the information of current location of the robot. So far, the location information that was obtained using Encoder always includes Dead Reckoning Error, which is accumulated continuously and gets bigger as the distance of movement increases. In this paper, we analyse the effect of the size of the two wheels of the mobile robot and the wheel track of them among the factors of Dead Reckoning Error. And after this, we compensate this Dead Reckoning Error by Kalman filter using Gyro Sensors. To accomplish this, we develop the controller to analyse the error components of Gyro Sensor and to minimize the error values. We employ the numerical approach to analyse the error components by linearizing them because each error component is nonlinear. And we compare the improved result through simulation.