• Journal of Magnetics
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• v.8 no.1
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• pp.74-78
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• 2003

The largest advantage of magnetic micromachine is wireless operation. This advantage makes it suitable for medical micromachine working inside the human body. In the medical field, low invasion treatment is very important From this point of view, very small machines working in the body without power supply cables meet the needs of the medical field. In this paper, we report about magnetic wireless actuators for medical applications.

• JSTS:Journal of Semiconductor Technology and Science
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• v.13 no.6
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• pp.562-568
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• 2013

This paper presents a design of a wireless power transfer system based on magnetic resonant coupling technology with in-band wireless communication. To increase the transmission distance and compensate for the change in the effective capacitance due to the varying distance, the proposed system used a loop antenna with a selectable capacitor array. Because the increased transmission distance enables multiple charging, we added a communication protocol operated at the same frequency band to manage a network and control power circuits. In order to achieve the efficient bandwidth in both power transfer mode and communication mode, the S-parameters of the loop antennas are adjusted by switching a series resistor. Our test results showed that the loop antenna achieved a high Q factor in power transfer mode and enough passband in communication mode.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.3
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• pp.275-281
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• 2016

A novel bidirectional magnetic wireless communication system is proposed in this study. This system provides the communication capability between the source and load sides by high-frequency signal while wireless power is transferred. Contrary to the conventional wireless communication systems using complex IC circuit and active components, the proposed system is simply composed of passive components. It is practical and beneficial for environmental robustness, cost effectiveness, and simple implementation. The detailed static analysis of the proposed system for power and communication lines is established. The proposed system is experimentally verified, and results show that a 0.1 voltage gain for communication line is obtained while a 2.0 voltage gain for the power line is achieved. The proposed system is adequate for practical applications as it allows the inductive power transfer system to wirelessly and easily communicate between the source and load sides.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.1
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• pp.61-68
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• 2017

In this paper, we propose an improved magnetic field shielding structure to reducing the magnetic field generated in the wireless power transfer system operating at a low frequency band. The proposed structure consists of the magnetic material and the conductive material, magnetic field cancelling effect for power transfer is minimized while improving the leakage magnetic field cancelling effect by optimizing the various design parameters in the proposed structure. We analyzed and verified the efficiency of the wireless power transfer system and the reduction effect of the leakage magnetic field through computer simulation and measurement. Analysis results show that power transfer efficiency of the wireless power transfer system utilizing the proposed structure is 77 %, which is maintained at the conventional power transfer efficiency. In addition, compared with the structure maintaining high power transfer efficiency, leakage magnetic field strength is reduced to 29~37 % at the nearest point.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.5
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• pp.985-988
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• 2017

Magnetic induction (MI) based communication is one of the near-field communication techniques, which makes use of induced magnetic fields. In order to develop the MI based underwater communication networks, we evaluate and compare the loss performance between direct-MI and MI-waveguide in underwater environment.

• Korean Journal of Materials Research
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• v.29 no.9
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• pp.532-541
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• 2019

Information and communication technologies are developing rapidly as IC chip size becomes smaller and information processing becomes faster. With this development, digital circuit technology is being widely applied to mobile phones, wireless LANs, mobile terminals, and digital communications, in which high frequency range of GHz is used. In high-density electronic circuits, issues of noise and EMC(Electro-Magnetic Compatibility) arising from cross talk between interconnects or devices should be solved. In this study, sheet-type electromagnetic wave absorbers that cause electromagnetic wave attenuation are fabricated using composites based on soft magnetic metal powder and silicon rubber to solve the problem of electromagnetic waves generated in wireless communication products operating at the frequency range of 2.4 GHz. Sendust(Fe-Si-Al) and carbonyl iron(Fe-C) were used as soft magnetic metals, and their concentrations and sheet thicknesses were varied. Using soft magnetic metal powder, a sheet is fabricated to exhibit maximum electromagnetic attenuation in the target frequency band, and a value of 34.2dB(99.9 % absorption) is achieved at the target frequency.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.11
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• pp.97-102
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• 2012

Recently, a wireless sensor network system has been receiving great attention for management of underground facilities. However, traditional wireless communication systems using microwaves in several hundred MHz ~ several GHz experience significant performance degradation in the non-uniform underground environment. In this research, in order to make a robust communication for the underground facilities, we propose a wireless underground sensor system based on magnetic field communication. In 3 meters underground environment including rocks, soils, water, etc.,, our proposed sensor network system has proved fully functional and met its performance specification.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.8
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• pp.4227-4240
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• 2019

In this paper, we present our proposed magnetic induction based wireless communication system. The proposed system is designed to perform communication as well as distance measurement in underground environments. In order to improve the communication quality, we propose and implement the adaptive channel compensation technique. Based on the fact that the channel may be fast time-varying, we keep track of the channel status each time the data is received and accordingly compensate the channel coefficient for any change in the channel status. By using the proposed compensation technique, the developed platform can reliably communicate over distances of 10m while the packet error rate is being maintained under 5%. We also implement the distance measurement block that is useful for various applications that should promptly estimate the location of nearby nodes in communication. The distance between two nodes in communication is estimated by generating a table describing pairs of the magnetic signal strength and the corresponding distance. The experiment result shows that the platform can estimate the distance of a node located within 10m range with the measurement error less than 50cm.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.10
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• pp.2239-2244
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• 2013

Industrial machines have constraints on movement due to its wire for power supply. Recently, the research on wireless power supply for industrial machine which is required to move freely is receiving a lot of attention. In this paper, we suggest a magnetic induction system which can charge a equipment's battery with wireless at a close range. The system was designed to operate at 13.56 MHz and a distance of 20~30 mm between the transmitting and the receiving power module. From experiment, it was found that it takes about 135 minutes for charging the battery with about 15 V using the proposed system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.5A
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• pp.464-472
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• 2011

As wireless sensor networks are applied to various applications such as environment monitoring and disaster sensing system, there are increased needs for wireless communication in underground environment. Since the previous wireless communication technology using electromagnetic wave is not appropriate for the underground environment, a new alternative is required. Recently a magnetic field communication technology has been proposed and standardized as a domestic KS standard. In this paper, we analyze the media access control protocol of the KS standard by an analysis and a simulation study.