• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.2 no.4
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• pp.73-80
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• 2009

In this paper, we implemented the integrated gateway for health care and home network system based on PLC(Power Line Communication) and Zigbee. The designed system is consists of sensors, integrated gateway, Zigbee module and PLC modem. The integrated gateway will transmit the data which is collected by health care sensors to health care control system and control an appliance for comfortable environment to medical facilities. The implemented gateway can support various health care and home network service.

• Journal of Electrical Engineering and Technology
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• v.9 no.6
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• pp.2224-2236
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• 2014

The performance of an isolated high voltage full bridge converter is improved using a voltage doubler. In a conventional high voltage full bridge converter, the diode of the transformer secondary voltage undergoes a voltage spike due to the leakage inductance of the transformer and the resonance occurring with the parasitic capacitance of the diode. In addition, in the phase shift control, conduction loss largely increases from the freewheeling mode because of the circulating current. The efficiency of the converter is thus reduced. However, in the proposed converter, the high voltage dual converter consists of a voltage doubler because the circulating current of the converter is reduced to increase efficiency. On the other hand, in the proposed converter, an input current is distributed when using parallel input / serial output and the output voltage can be doubled. However, the voltages in the 2 serial DC links might be unbalanced due to line impedance, passive and active components impedance, and sensor error. Considering these problems, DC injection is performed due to the complementary operations of half bridge inverters as well as the disadvantage of the unbalance in the DC link. Therefore, the serial output of the converter needs to control the balance of the algorithm. In this paper, the performance of the conventional converter is improved and a balance control algorithm is proposed for the proposed converter. Also, the system of the 1.5[kW] PCS is verified through an experiment examining the operation and stability.

• KEPCO Journal on Electric Power and Energy
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• v.5 no.3
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• pp.149-156
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• 2019

In the field of maintenance of power transmission lines, drones have been used for their patrol and inspection by KEPCO since 2017. This drone technology was originally developed by KEPCO Research Institute, and now workers from four regional offices of KEPCO have directly applied this technology to the drone patrol and inspection tasks. In the drone inspection system, a drone with an optical zooming camera and a thermal camera can fly automatically along the transmission lines by the ground control system developed by KEPCO Research Institute, but its camera gimbal has been remotely controlled by a field worker. Especially the drone patrol and inspection has been mainly applied for the transmission lines in the inaccessible areas such as regions with river-crossings, sea-crossings and mountains. There are often communication disruptions between the drone and its remote controller in such extreme fields of mountain areas with many barriers. This problem may cause the camera gimbal be out of control, even though the inspection drone flies along the flight path well. In addition, interference with the reception of real-time transmitted videos makes the field worker unable to operate it. To solve these problems, we have developed the auto-tracking camera gimbal system with deep learning method. The camera gimbal can track the transmission line automatically, even when the transmitted video on a remote controller is intermittently unavailable. To show the effectiveness of our camera gimbal system, its field test results will be presented in this paper.

• Journal of Advanced Navigation Technology
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• v.5 no.1
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• pp.54-61
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• 2001

In conventional Ultra Wide Band(UWB) system, it uses Pulse Positioning Modulation Method to modulate data signal. In this paper, however, we derive power spectral density characteristic of time hopped antipodal signal using stochastic process. UWB signal employes Gaussian monopulse and Rayleigh monopulse which pulse width is 0.5 nsec and interval is 5 nsec. But comb line which produces unintentionally could be evidently reduced by the time hopped code, so this code be used to channelize for multiple access and minimize to different communication system.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.1
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• pp.147-152
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• 2008

This paper has been fabricated the two different type of variable attenuators using a characteristics of a 3 dB directional coupler and pin diodes. One was not analyzed using the conventional even-odd modes but used simple two-port techniques. The resulting scattering parameters described operation characteristics for the general case where the terminating impedances are equal and unequal. After analyzing resistor role of the ${\pi}$ type fixed attenuator. this paper used a pin diode instead of a resistor. The variable attenuators were fabricated using pin diodes for current-controlled attenuation on the coupled ports of a 3 dB branch-line coupler and ${\pi}$ type fixed attenuator. The realized variable attenuators have more than 33 dB attenuation ranges at 2.1 GHz. and the input and output reflection coefficients are less than -13 dB. These results could be applied to mobile communication systems. It can be varied gain of the power amplifier according to change a outdoor environmental temperature and improved linearity.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.6
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• pp.873-880
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• 2011

As environmental pollution, global warming, and exhaustion of fossil fuel become global issue recently, there has been strong research motivation to develop green energy technology. Along the same line of motivation, some research efforts have been put into the development of environment-friendly bicycle equipped with various smart energy technologies to increase the usability of the bicycle as short-distance transportation. Among the technologies related with new generation bicycle, PAS (power assist system) is one of the most important systems that are essential in efficiently integrating human power and the electrical power supplied by electric motor driven by battery. In this paper, a novel torque sensor technology which is core component for PAS is proposed. Unlike existing technologies, strain gauges are attached to rear shaft directly under the hub bearings, which eliminates the requirement of slip-ring, Furthermore, the sensor is able to not only measure the torque transmitted to driving axle by human but also estimate the position of the gear to which the chain is currently engaged.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.1
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• pp.207-212
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• 2017

The cables installed to deliver high electric power from a generator at a thermoelectric power station are XLPE (or CV) cables. Depending on the installation and usage conditions, the cables in operation start deteriorating from the time of initial operation. Some cables can cause accidents due to faulty construction or other environmental factors. In order to prevent cable accidents, regular auditing of power cables is required. We have invented a measuring device for systematic surveillance and prevention of accidents, and installed the device at Korean Western Power Co. Ltd. which measures load currents through the cables. In this paper, we present the load current measured using our device, analyze the load characteristics by measures current, compare the ampacity defined by IEC standard, and present a basic data to obtain the temperature of cable conductors.

• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.3
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• pp.334-341
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• 2015

This research outlines the design of a HR-TDC (High Resolution Time-to-Digital Converter) for high data rate communication systems using a $0.18{\mu}m$ CMOS process. The coarse-fine architecture has been adopted to improve the resolution of the TDC. A two-stage vernier time amplifier (2S-VTA) was used to amplify the time residue, and the gain of the 2S-VTA was larger than 64. The error during time amplification was compensated using two FTDCs (Fine-TDC) with their outputs. The resolution of the HR-TDC was 0.15 ps with a 12-bit output and the power consumption was 4.32 mW with a 1.8-V supply voltage.

• Journal of Electrical Engineering and Technology
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• v.4 no.1
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• pp.13-18
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• 2009

Because the existing Human-Machine Interface (HMI) for the conventional substation cannot dynamically indicate the configuration information of the Substation Automation System (SAS). In this paper, an intelligent station HMI is proposed for IEC 61850 based substation. The program of the proposed HMI not only can automatically generate the layout of single line diagram, but can also indicate the communication network and functions of IEDs by reading SCL files. It greatly helps monitor the operation status, communication network and each IED dynamically, such as failure detection in SAS. Furthermore, this paper presents the possibility of developing new software for SAS with the full use of IEC 61850-6. Once the software is complete, there is no need to change it when the substation is upgraded or when it is migrated to other IEC 61850 based substations, which is a cost-effective solution.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.1
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• pp.152-167
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• 2016

This paper investigates the simultaneous wireless information and power transfer (SWIPT) for two-hop orthogonal frequency division multiplexing (OFDM) decode-and-forward (DF) relay network, where a relay harvests energy from radio frequency signals transmitted by a source and then uses the harvested energy to assist information transmission from the source to its destination. The power splitting receiver is considered at the relay. To explore the performance limit of such a SWIPT-enabled system, a resource allocation (RA) optimization problem is formulated to maximize the achievable information rate of the system, where the power allocation, the subcarrier pairing and the power splitting factor are jointly optimized. As the problem is non-convex and there is no known solution method, we first decompose it into two separate subproblems and then design an efficient RA algorithm. Simulation results demonstrate that our proposed algorithm can achieve the maximum achievable rate of the system and also show that to achieve a better system performance, the relay node should be deployed near the source in the SWIPT-enabled two-hop OFDM DF relay system, which is very different from that in conventional non-SWIPT system where the relay should be deployed at the midpoint of the line between the source and the destination.