• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.37-38
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• 2010

For MHz-class high frequency inverter in wireless power transfer applications, the voltage/current surges can be occurred in power stage when driving on the inverter. And also, the high-frequency oscillations can be produced at a high switching frequency due to the parasitic elements. The voltage and current stresses of the switching devices lead to the switching losses. The efficiency of the high frequency inverter will be reduced. And the inverter circuit with the sudden voltage and current fluctuations also generates the noise such as the EMI. Zero voltage, zero current switching technique can be used to reduce the switching loss and the noise. The high power density and high efficiency can be obtained. In this paper, the high-frequency inverter for short-range wireless power transfer applications was discussed. The feasible inverter circuit is analyzed in the circuit operating characteristics and the results are verified by the simulation.

• Journal of Information Processing Systems
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• v.10 no.2
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• pp.300-313
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• 2014

Various Time Synchronization protocols for a Wireless Sensor Network (WSN) have been developed since time synchronization is important in many time-critical WSN applications. Aside from synchronization accuracy, energy constraint should also be considered seriously for time synchronization protocols in WSNs, which typically have limited power environments. This paper performs analysis of prominent WSN time synchronization protocols in terms of power consumption and test by simulation. In the analysis and simulation tests, each protocol shows different performance in terms of power consumption. This result is helpful in choosing or developing an appropriate time synchronization protocol that meets the requirements of synchronization accuracy and power consumption (or network lifetime) for a specific WSN application.

• Journal of electromagnetic engineering and science
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• v.16 no.4
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• pp.232-234
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• 2016

In this paper, the power transfer efficiencies (PTEs) of magnetic resonance (MR) wireless power transmission (WPT) and radio frequency (RF) WPT are compared as a function of the distances between resonators (or antennas). The PTE of the C-loaded loop resonators during MR WPT was theoretically calculated and simulated at 6.78MHz, showing good agreement. The PTE of the patch antennas, whose area is the same as the C-loaded loop resonator during MR WPT, was theoretically calculated using the Friis equation and the equation by N. Shinohara and simulated at 5.8 GHz. The three results from the Friis equation, the equation by N. Shinohara, and from a full wave simulation are in strong agreement. The PTEs, when using the same size resonators and antennas are compared by considering the distance between the receiver and transmitter. The compared results show that the MR WPT PTE is higher than that of the RF WPT PTE when the distance (r) between the resonators (or antennas) is shorter. However, the RF WPT PTE is much higher than that of the MR WPT PTE when the distance (r) between the resonators (or antennas) is longer since the RF WPT PTE is proportional to $r^{-2}$ while the MR WPT PTE is proportional to $r^{-6}$.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.12
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• pp.3018-3036
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• 2013

In this paper, we investigate power allocation scheme and outage performance for a physical-layer network coding (PNC) relay based secondary user (SU) communication in cognitive multi-antenna relay networks (CMRNs), in which two secondary transceivers exchange their information via a multi-antenna relay using PNC protocol. We propose an optimal energy-efficient power allocation (OE-PA) scheme to minimize total energy consumption per bit under the sum rate constraint and interference power threshold (IPT) constraints. A closed-form solution for optimal allocation of transmit power among the SU nodes, as well as the outage probability of the cognitive relay system, are then derived analytically and confirmed by numerical results. Numerical simulations demonstrate the PNC protocol has superiority in energy efficiency performance over conventional direct transmission protocol and Four-Time-Slot (4TS) Decode-and-Forward (DF) relay protocol, and the proposed system has the optimal outage performance when the relay is located at the center of two secondary transceivers.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.2
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• pp.196-200
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• 2013

In this paper, the design of PRT vehicle power supply system is discussed. Since there is no power feeding line facilities in PRT system under development, the PRT vehicle must have its own energy storage device on board. For the energy storage device, ultra-capacitor bank is applied due to its fast charging capability and long life time. Charging the Ultra-capacitor bank is performed by wireless inductive power transfer system. The capacitor bank is charged up in less than 10 seconds when the vehicle is traveling by passenger stations. In this paper the design of the ultra-capacitor bank and the wireless inductive power transfer system for the PRT vehicle are discussed. Tests are conducted for the both system and the result shows the efficiency of the wireless inductive power transfer system is higher than 80%.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.543-544
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• 2007

This paper introduce methods and analysis of a simple wireless sensor concept for detecting and locating faults as well as for load monitoring are presented. The concept is based on distributed wireless sensors that are attached to the incoming and outgoing power lines of secondary substations. A sensor measures only phase current characteristics of the wire it is attached to, is not synchronized to other sensors and does not need configuration of triggering levels. The main novelty of the concept is in detecting and locating faults by combining power distribution network characteristics on system level with low power sampling methods for individual sensors. This concept enables the sensor design to be simple, energy efficient and thus applicable in new installations and for retrofit purposes in both overhead and underground electrical distribution systems.

• Journal of Power System Engineering
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• v.15 no.5
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• pp.49-53
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• 2011

This study concerns about wireless power generation that uses the energy harvester with EAP actuator. The UWSN(Underwater Wireless Sensor Network) has been considered many times by many researches. Because the information of underwater is getting important to secure the resource or to predict the meteorological phenomena. But the sensor node in the UWSN is driven by the acoustic wave to communicate with other sensor node. And this acoustic wave usually spends a 100 times energy than the RF(Radio Frequency) wave due to transfermation medium(sea water). Therefore the power source of the sensor node is very important that is needed to improve in the UWSN. For this purpose, the energy harvester is made by the acrylic elastomer in this study. And the electrode is modified with an aluminum impurity to improve the efficiency of energy harvester. After that, the modified energy harvester is experimented to confirm the improvement of the energy efficiency.

• Journal of Korea Multimedia Society
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• v.19 no.8
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• pp.1471-1478
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• 2016

In this study, the system to manage the power automatically was implemented by using Arduino, Raspberry pi, and Beacon technologies. Before the research, pre-research was carried out with the analysis on the existing power management systems in the market in order to find a solution to reduce burdens from standby power and power waste with the increase of electric charges. The system is designed to be able to deliver and receive data through IEEE 802.15.4 wireless protocol, by using Xbee module. Arduino was tested to verify whether it is able to control SSR(Solid State Relay), and it was found that there is no problem. Meanwhile, it was also tested whether it is possible to organize a star topology network through Arduino and Raspberry Pi, and it was confirmed that normal wireless communication is possible through IEEE 802.15.4 wireless protocol. It is designed that the signal from Android smartphone application is to be delivered to Raspberry Pi and then, to be delivered to Arduino through Xbee so that Arduino could control SSR. In addition to this, wireless protocol required to control Arduino with Raspberry Pi is also designed and applied to this research.

• Journal of Magnetics
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• v.21 no.4
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• pp.652-659
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• 2016

In this study, the efficiencies for both the angular aligned and unaligned positions of the receiver and transmitter coils of wireless power transfer (WPT) systems are examined. Some parameters of the equivalent circuit were calculated with Maxwell 3D software. The analytical solution of the circuit was calculated in MATLAB program through the composition of the system's mathematical modeling. The numerical solution of the system, however, was calculated using PSIM, which is circuit simulation software. In addition, with the use of the finite element method (FEM) in Maxwell 3D software, transient analysis of the three-dimensional system was performed. The efficiency of the system was estimated through the calculation of input and output power. The results demonstrated that power was efficiently transmitted to a certain extent in aligned and unaligned positions. The results also revealed that, for aligned positions, high efficiency with air gaps of 15-20 cm can be obtained and that the efficiency quickly dropped with air gaps of more than 20 cm. For spatially unaligned positions, it was observed that wireless power transfer could be realized with high efficiency with air gaps of up to 10 cm and that efficiency quickly dropped with air gaps of more than 10 cm.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.5
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• pp.521-524
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• 2015

This letter presents a selective wireless power transfer architecture using a reconfigurable multi-port amplifier. The proposed wireless power transfer architecture is composed of a phase shifter part controlled by FPGA, two class-E power amplifiers, a four-port power combiner and two coil loads. Depending on the phase control of FPGA, the power ratio of outputs at the two coil loads becomes 1:1, 2:0 and 0:2. The manufactured system has delivered 1W DC power to loads at 125 kHz. The total DC-to-DC conversion efficiency shows more than 40 % including PA efficiency of 79 %.