• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.1
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• pp.213-218
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• 2017

High-voltage power systems operate in order to generate and transmit electric power at power stations. Compared to low-power systems, high-power systems are complex in structure, large-scale, and expensive. When high-power cable accidents occur, most facilities are incapacitated-including low-power systems-causing huge economic losses. Great care must therefore be taken in designing, installing and managing power systems. Although dependent on installation circumstances and usage conditions, in some cases the cross-sectional areas of cables fall short of the critical area due to the expansion of and improper design and installation of power facilities. In this situation, the exceeded ampacity (allowable current) above the critical value caused by the operating current initiates the deterioration processes of power cables. In order to systematically monitor power cables operating at power stations, we have developed the first device of its kind in Korea. In this paper, we present the analyzed characteristics of expected temperatures of cables based on the load current of high-voltage cables operating at Korean Western Power Co. Ltd. We can predict the lifetime of cables by analyzing the temperature obtained from our device.

• Korean Journal of Materials Research
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• v.24 no.3
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• pp.152-158
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• 2014

We report the effect of the fabric of the surface microstructure on the CO gas sensing properties of $SnO_2$ thin films deposited on self-assembled Au nanodots ($SnO_2$/Au) that were formed on $SiO_2/Si$ substrates. We characterized structural and morphological properties, comparing them to those of $SnO_2$ thin films deposited directly onto $SiO_2/Si$ substrates. We observed a significant enhancement of CO gas sensing properties in the $SnO_2$/Au gas sensors, specifically exhibiting a high maximum response at $200^{\circ}C$ and quite a low detection limit of 1 ppm level in dry air. In particular, the response of the $SnO_2/Au$ gas sensor was found to reach the maximum value of 32.5 at $200^{\circ}C$, which is roughly 27 times higher than the response (~1.2) of the $SnO_2$ gas sensor obtained at the same operating temperature of $200^{\circ}C$. Furthermore, the $SnO_2/Au$ gas sensors displayed very fast response and recovery behaviors. The observed enhancement in the CO gas sensing properties of the $SnO_2/Au$ sensors is mainly ascribed to the formation of a nanostructured morphology in the active $SnO_2$ layer having a high specific surface-reaction area by the insertion of a nanodot form of Au nucleation layer.

• Journal of information and communication convergence engineering
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• v.7 no.1
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• pp.72-77
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• 2009

Three different procedures for adding Pd compounds to $SnO_2$ particles have been investigated. These processes are: (1) coprecipitation; (2) dried powder impregnation; and (3) calcined powder impregnation. The microstructures of $SnO_2$ particles have been analyzed by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). In the coprecipitaion method, the process does not restrain the growth of $SnO_2$ particles and it forms huge agglomerates. In the dried powder impregnation method, the process restrains the growth of $SnO_2$ particles and the surfaces of the agglomerates have many minute pores. In the calcined powder impregnation method, the process restrains the growth of $SnO_2$ particles further and the agglomerates have a lot more minute pores. The sensitivity ($S=R_{air}/R_{gas}$) of the $SnO_2$ gas sensor made by the calcined powder impregnation process shows the highest value (S = 21.5 at 5350 ppm of $C_3H_8$) and the sensor also indicates the lowest operating temperature of around $410^{\circ}C$. It is believed that the best result is caused by the plenty of minute pores at the surface of the microstructure and by the catalyst Pd that is dispersed at the surface rather than the inside of the agglomerate. Schematic models of Pd distribution in and on the three different $SnO_2$ particles are presented.

• Korean Journal of Agricultural and Forest Meteorology
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• v.25 no.3
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• pp.226-235
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• 2023

This study aimed to supplement the shortcomings of the Multiple-sensor-based Frost Observation System (MFOS). The developed frost observation system is an improvement of the existing system. Based on the leaf wetness sensor (LWS), it not only detects frost but also functions to predict surface temperature, which is a major factor in frost occurrence. With the existing observation system, 1) it is difficult to observe ice (frost) formation on the surface when capturing an image of the LWS with an RGB camera because the surface of the sensor reflects most visible light, 2) images captured using the RGB camera before and after sunrise are dark, and 3) the thermal infrared camera only shows the relative high and low temperature. To identify the ice (frost) generated on the surface of the LWS, a LWS that was painted black and three sheets of glass at the same height to be used as an auxiliary tool to check the occurrence of ice (frost) were installed. For RGB camera shooting before and after sunrise, synchronous LED lighting was installed so the power turns on/off according to the camera shooting time. The existing thermal infrared camera, which could only assess the relative temperature (high or low), was improved to extract the temperature value per pixel, and a comparison with the surface temperature sensor installed by the National Institute of Meteorological Sciences (NIMS) was performed to verify its accuracy. As a result of installing and operating the MFOS v2, which reflects these improvements, the accuracy and efficiency of automatic frost observation were demonstrated to be improved, and the usefulness of the data as input data for the frost prediction model was enhanced.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.10
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• pp.2503-2508
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• 2014

This study is about the selection and noise test of electronic sensor which is preceded by electric Operating Cell(EOC) development using electronic sensor technology to solve the structural weakness of Mechanism Operated Cell(MOC) in VCB, and has a final target in product development minimizing contact malfunction of the chattering or rebounce states caused by existing MOC. In this test results, when opening and closing VCB, rising velocity of surge voltage in opening time was measured 4.2 times faster than closing time and noise decibel value was measured respectively 120dB and 110dB. When supplying 60kV power frequency overvoltage, we found that sensor output graph in VCB opening and closing times operated stably without distortion. When supplying 150kV $1.2{\times}50{\mu}s$ impulse frequency voltage, we found that voltage graph of output contact in sensor opening and closing sides maintained a normal condition without distortion, and when supplying 2500A current, we found that tested result of electric field noise operated stably without distortion.

• Journal of Navigation and Port Research
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• v.42 no.6
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• pp.421-426
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• 2018

With regard to LED lighting devices which have currently been commercialized, LED operating sequences are being sold in a fixed state. In such a state, the external environmental factors are not taken into consideration as only the illumination environment application is considered. Currently, it is difficult to create an optimal lighting environment which can adapt to changes in external environmental factors in the ship. Therefore, it was concluded that there is a need to input the external environment value so that the optimal illumination value can be reflected in real time in order to adapt more organically and actively to the change of external environmental factors. In this paper, we used a microprocessor as an integrated management system for environmental data that changes in real time according to existing external environmental factors. In addition, a controller capable of lighting control of RGB LED module by combining fuzzy inference system. For this, a fuzzy control algorithm is designed and a fuzzy control system is constructed. The distance and the illuminance value from the external environment element are input to the sensor, and these values are converted to the optimum illumination value through the fuzzy control algorithm, and are expressed through the dimming control of the RGB LED module and the practical effectiveness of the fuzzy control system is confirmed.

• Journal of Positioning, Navigation, and Timing
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• v.4 no.1
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• pp.1-7
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• 2015

In the case of an unmanned aerial vehicle (UAV) equipped with a GNSS sensor, a boundary line where the vehicle can actually exist can be calculated using a navigation error model, and safe navigation (e.g., precise landing and collision prevention) can be supported based on this boundary line. Therefore, for the safe operation of UAV, a model for the position error of UAV needs to be established in advance. In this study, the multipath error of a GNSS sensor installed at UAV was modeled through a flight test, and this was analyzed and compared with the error model of an existing manned aircraft. The flight test was conducted based on a scenario in which UAV performs hovering at an altitude of 40 m, and it was found that the multipath error value was well bound by the error model of an existing manned aircraft. This result indicates that the error model of an existing manned aircraft can be used in operation environments similar to the scenario for the flight test. Also, in this study, a scenario for the operation of multiple UAVs was considered, and the correlation between the multipath errors of the UAVs was analyzed. The result of the analysis showed that the correlation between the multipath errors of the UAVs was not large, indicating that the multipath errors of the UAVs cannot be canceled out.

• Transactions of the Korean Society of Automotive Engineers
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• v.25 no.1
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• pp.60-65
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• 2017

We designed and fabricated the engine oil monitoring sensor to measure engine oil deterioration through increased vehicle mileage. Since the condition of the engine oil can be affected by the state of the vehicle and its operating conditions, it should be directly measured and determined in every vehicle. The fabricated sensor has an aluminum parallel capacitor structure that measures capacitance related with the dielectric constant, which is one of the indices of oil deterioration. The size of the capacitor is small enough that it could be easily adapted on the oil level gauge without introducing any change in the design. The fabricated device is installed in the diesel engine to measure the change in capacitance accurately as the vehicle moved from 0 km (new engine oil state) to 11,364 km. The results showed the maximum value at around 5,000 km, and the values plateaued as mileage increased, corresponding with the measurement result of the TAN (Total Acid Number). Based on the results, the condition of the oil must be monitored regularly though oil change is recommended once the vehicle has traveled the distance of around 10,000 km.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.20 no.3
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• pp.86-99
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• 2021

This research proposes the Accident Prevention System to prevent collision accident that can occur due to blind spots such as crossway or school zone using V2I communication. Vision sensor and LiDAR sensor located in the infrastructure of crossway somewhere like that recognize objects and warn vehicles at risk of accidents to prevent accidents in advance. Using deep learning-based YOLOv4 to recognize the object entering the intersection and using the Manhattan Distance value with LiDAR sensors to calculate the expected collision time and the weight of braking distance and secure safe distance. V2I communication used ROS (Robot Operating System) communication to prevent accidents in advance by conveying various information to the vehicle, including class, distance, and speed of entry objects, in addition to collision warning.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.4
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• pp.151-159
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• 2015

In this study, we developed an automated contact-type thickness measurement machine that continuously and precisely measures the thickness of a PCB module product using multi-LVDT sensors. The system contains a measurement part to automatically measure the thickness in real time according to the set conditions with an alignment supply unit and unloading unit to separate OK and NG products. The sensors were calibrated before assembly in the measuring machine, and precision and accuracy performance tests were also performed to reduce uncertainty errors in the measurement machine. In the calibration test, the precision errors of the LVDT sensor were determined to be $1-3{\mu}m$ as 0.1% at the measuring range. A measurement error of 0.8 mm and 1.0 mm thickness test standards were found to be $1{\mu}m$ and $4{\mu}m$, and the standard deviations of two 1.0 mm products were measured as $14{\mu}m$ and $8{\mu}m$, respectively. In the measurement system analysis, the accuracies of test PCB standards were found to be $2{\mu}m$ and $3{\mu}m$, respectively. From the results of gage repeatability and reproducibility (R & R) crossed, we found that the machine is suitable for the measurement and process control in the mass production line as 7.92% of total gage R & R and in seven distinct categories. The maximum operating speed was limited at 13 pcs/min, showing a value good enough to measure.