• KEPCO Journal on Electric Power and Energy
• /
• v.7 no.2
• /
• pp.215-220
• /
• 2021

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.48 no.6
• /
• pp.34-42
• /
• 2011

With the progress of USN technology, fields to which wireless sensor node is applicable are increased under a condition that it holds a lot of problems to solve for betterment. One of the problems which acts as an obstacle to USN industry diffusion is the wireless sensor node battery exchange to their individual life cycle. Exchanging the battery of so many sensor nodes one by one requires a great deal of times and costs. Such problem is against the convenience supply -aim by applying USN technology. In this paper, using RF wireless power transmission system that power transmission / harvesting module from a distance of 5 m and the power of 10 dBm with a current of 1 mA or more for Sensor Nodes in lithium-polymer battery charging system tested and verified.

• Journal of Advanced Marine Engineering and Technology
• /
• v.35 no.4
• /
• pp.506-511
• /
• 2011

In this paper, a rectenna for wireless power transmission at 900MHz is proposed. Rectenna is a device transforming RF power into DC power and it may consist of a antenna, rectifying and charging circuits. In this paper, we designed a slot antenna to receive 900MHz signal, a rectifying circuit of about 40% efficiency at 0dBm input, and a charging circuit to store a weak power signal and supply constant voltage to load. From the experiment using a RFID reader as a transmitter for 1W power, it was found that the proposed rectenna receiving about 0dBm power can supply 3.3V constant voltage to 50$k{\Omega}$ load during 280sec.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.25 no.1
• /
• pp.44-53
• /
• 2020

A bridgeless single-stage AC-DC converter for wireless power charging systems is proposed. This converter is composed of a PFC stage and a three-level hybrid DC-DC stage. The proposed converter can control the wide output voltage (200-450 V_DC) by the variable link voltage and the pulse-width voltage applied to the primary resonant circuit due to the phase-shifted modulation at a fixed switching frequency. Moreover, the input power factor and the total harmonic distortion can be improved by using the proposed converter. A 1 kW prototype was fabricated and validated through experimental results and analysis.

• Journal of IKEEE
• /
• v.23 no.2
• /
• pp.747-750
• /
• 2019

Wearable devices have become practically indispensable to daily life and helped people track and manage fitness, health, and medical functions etc. As these wearable devices become smaller and more comfortable for the user, the demand for longer run time and charging ways presents new challenges for the power management engineer. Wireless power transfer (WPT) is the technology that forces the power to transmit electromagnetic field to an electrical load through an air gap without interconnecting wires. This technology is widely used for the applications from low power smart phone to high power electric railroad and main electrical grid. There are two kinds of WPT methods: Inductive coupling and magnetic resonant coupling. The model using magnetic resonant coupling method is designed for a resonant frequency of 13.45 MHz. In this study, the hardware implementations of these two coupling methods are carried out, and the efficiencies are compared.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.26 no.2
• /
• pp.141-149
• /
• 2021

In the field of electric vehicles and AGVs, wireless power transfer (WPT) charging systems have been developed recently because of its convenience, reliability, and positive environmental impact due to cable and cord elimination. In this study, we propose a WPT charging system using a single stage AC-DC converter that can be reduced in size and weight and thus can ensure convenience. The proposed single-stage AC-DC converter can control a wide output voltage (36-54 VDC) within coupling ranges by using the variable link voltage applied to the WPT resonant circuit through phase-shifted modulation at a fixed switching frequency. Moreover, the input power factor and total harmonic distortion can be improved by using the proposed converter. A 1 kW prototype that can operate with an air gap range of 40-50 mm is fabricated and validated through experimental results and analysis.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.27 no.1
• /
• pp.1-6
• /
• 2017

Recent researches on radio frequency energy harvesting networks(RF-EHNs) with limited energy resource like battery have been focusing on the development of a new scheme that can effectively extend the whole lifetime of a network to semipermanent. In order for considerable increase both in the amount of energy obtained from radio frequency energy harvesting and its charging effectiveness, it is very important to design a network that supports energy harvesting and data transfer simultaneously with the full consideration of various characteristics affecting the performance of a RF-EHN. In this paper, we proposes an interference-based charging aware routing protocol(ICARP) that utilizes interference information and charging time to maximize the amount of energy harvesting and to minimize the end-to-end delay from a source to the given destination node. To accomplish the research objectives, this paper gives a design of ICARP adopting new network metrics such as interference information and charging time to minimize end-to-end delay in energy harvesting wireless networks. The proposed method enables a RF-EHN to reduce the number of packet losses and retransmissions significantly for better energy consumption. Finally, simulation results show that the network performance in the aspects of packet transmission rate and end-to-end delay has enhanced with the comparison of existing routing protocols.

• Journal of Digital Contents Society
• /
• v.5 no.3
• /
• pp.234-238
• /
• 2004

The system facilities in mobile communications networks are mainly classified into the coverage and usage in the viewpoint of the investments requirements. Based on the classification criterion, the interconnection charging between the wired operators art wireless operators is determined. In this paper, to decide the scale of the interconnection charging a new classification method is proposed by using the system capacity(Erlang, throughput) and subscriber`s estimated demand. The coverage ratio is first evaluated for each facility, and then more efficient interconnection charging model will be presented.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.3B
• /
• pp.288-303
• /
• 2009

In the near future it is foreseen that a genuine multimedia service over the WiMAX system is provided in a worldwide manner by exploiting the QoS technologies introduced in the wireless and wired broadband network. In this work we propose a pricing scheme for the multimedia service over the generic WiMAX system that supports a full QoS functionality. We assume real-time services such as the voice and video as well as the nonreal-time service such as the conventional high-speed data, and we propose a pricing and charging scheme for those services by investigating the inherent characteristics of those services and the multiple-class of QoS-service provided to them. After that we propose a method to compute expected revenue that is obtained from the WiMAX system by using an analytic method to estimate the usage of the bandwidth resources for the different class of services. Via numerical experiment, we verify the implication of the work.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.21 no.6
• /
• pp.542-545
• /
• 2016

This work proposes a capacitive coupling-based wireless battery charging circuit that is built with vehicle glasses for electric vehicles. A capacitive coupling wireless power transfer offers many advantages, such as low metal impact and low energy transfer efficiency changes in accordance with changes in position. However, a large coupling capacitor is needed for high power transfer. Therefore, a new capacitive coupling-based wireless power transfer LLC resonant converter built with the glasses of an electric vehicle is proposed. The proposed converter is composed of coupling capacitors with glasses of an electric vehicle and two transformers for impedance transformation. The proposed LLC converter can transfer large power and obtain high efficiency with zero voltage switching. The validity and features of the proposed circuit is verified by experimental results with a 1.2 kW prototype.