• ETRI Journal
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• v.36 no.5
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• pp.808-818
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• 2014

To deal with the major challenges of embedded sensor networks, we consider the use of magnetic fields as a means of reliably transferring both information and power to embedded sensors. We focus on a power allocation strategy for an orthogonal frequency-division multiplexing system to maximize the transferred power under the required information capacity and total available power constraints. First, we consider the case of a co-receiver, where information and power can be extracted from the same signal. In this case, we find an optimal power allocation (OPA) and provide the upper bound of achievable transferred power and capacity pairs. However, the exact calculation of the OPA is computationally complex. Thus, we propose a low-complexity power reallocation algorithm. For practical consideration, we consider the case of a separated receiver (where information and power are transferred separately through different resources) and propose two heuristic power allocation algorithms. Through simulations using the Agilent Advanced Design System and Ansoft High Frequency Structure Simulator, we validate the magnetic-inductive channel characteristic. In addition, we show the performances of the proposed algorithms by providing achievable ${\eta}$-C regions.

• Proceedings of the KIPE Conference
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• 2013.11a
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• pp.224-226
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• 2013

본 논문은 유도가열 시스템의 자성체 판별 알고리즘을 제안한다. 코일의 형상 및 구성에 따른 임피던스를 수학적으로 분석하여 자성체와 비자성체 동시 가열을 위한 유도 코일을 능동적으로 설계 한다. 또한 인버터 출력전압과 부하 전류를 센싱하여 계산한 임피던스 값과 수식으로 구한 부하 임피던스를 비교해 가열 용기의 재질을 판별한다. 제안된 알고리즘을 통해 자성체 및 비자성체 유도가열을 하나의 공진형 인버터로 구현할 수 있다. 제안된 판별법은 시뮬레이션을 통해 검증한다.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.5
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• pp.935-942
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• 2019

This paper descries the operation of a heater which was designed to control a motor that generates an eddy current. As the motor drives the rotor of an eddy current heater, magnetic fields are provided within the air gap between an eddy current heater's rotor and stator. Throughout the research, a rotor composed of 8 and 16 pieces of magnets was used to analyze which are the factors that affect the efficiency of this equipment. Test results showed that the magnetic fields are influenced by variable functions including the velocity of a motor and the quantity of magnets composing a rotor.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.3
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• pp.206-212
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• 2017

Induction motor torque is the reactive power is needed which corresponds to the exciting current to generate the magnetic flux as the product of current and flux. For use in the method of supplying the required reactive power to the induction motor power factor correction apparatus using a lot of ways to supply in place of the power supply side, when using a power factor compensation device can reduce the apparent power, the power factor can be improved. However, the distance to the emergency generator transformers or motors from the motor capacity is smaller but short and difficult to maneuver the theory and practice of the operating characteristics of the starting characteristics of the motor used a lot of large industrial plants were measured and analyzed. Therefore, this study investigated the motor starting Analysis and interpretation for the relationship with the large motor starting torque and speed during motor starting.

• The Journal of the Korea institute of electronic communication sciences
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• v.19 no.3
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• pp.497-506
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• 2024

In this paper, medium-power wireless power transmission is implemented using the commercial power frequency (60 Hz). Since general magnetic induction wireless power transmission devices use more than several tens of kHz, the commercial power frequency (60 Hz) cannot be used as is. Therefore an AC/DC converter is used to convert the 60 Hz power frequency into DC, and a high-frequency power amplifier is used to convert DC into several tens of kHz. In magnetic induction wireless power transmission, the AC/DC converter and high-frequency power amplifier are removed, and a extremely low frequency wireless power transmission(ELF-WPT) system using commercial frequency consisting of only transmitting resonance tank, transmitting coil, receiving resonance tank, and receiving coil is implemented, and verified through wireless power transmission experiments.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.6
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• pp.815-822
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• 2013

In this paper, the research is to develop a system that can detect the breakage of the rubber belt conveyor system in the transport of the raw materials required for the operation of logistics. We are to develop a system that can detect the breakage of the belt due to the electronic system of belt breakage occurs by placing the material on the inside of the belt, electric induction to minimize the damage of the belt. The belt repair costs, or reorder the steps of the logistics transit time can be reduced. Induced in the coil, and belt embedded in the transmitted signal as a way to detect the breakage of the belt was to detect the damage of the belt by detecting the electrical phenomena induced in the coil at the receiving end.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.2
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• pp.131-136
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• 2021

A DC motor is an important driving source used in a wide range along with an induction motor. Although the structure is complex and has disadvantages in terms of maintenance, most of the demands are given to induction motors as a power source in the industry today, but due to its excellent control performance, DC motors are constantly being used as small-sized control motors. In addition, DC motors with a structure capable of high-power and high-efficiency operation are being developed with the development of magnetic materials as a structure capable of using a permanent magnet in a armature. In addition, the configuration of the controller is simpler than that of an induction motor using an inverter, and the demand for a DC motor is still not negligible, so it is still occupied as an important power source. Considering these trends, this paper attempts to investigate the control performance of DC motors through hardware implementation such as modeling through simulation, PWM generation circuit and electric motor circuit using EPLD, and PI control using processor.

• Journal of the Korean Magnetics Society
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• v.17 no.6
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• pp.232-237
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• 2007

We have synthesized the low temperature sintered of Ni-Zn-Cu ferrite with nonstoichiometric composition a little deficient in $Fe_2O_3$ from $(Ni_{0.2}Cu_{0.2}Zn_{0.6})_{1+x}(Fe_2O_3)_{1-x}$. For low loss and acceleration of grain growth $TiO_2$ and $Li_2CO_3$ was added from 0.25 mol% to 1.0 mol%. The mixture of the law materials was calcinated and milled. The compacts of toroidal type were sintered at different temperature $(875^{\circ}C,\;900^{\circ}C,\;925^{\circ}C\;950^{\circ}C)$ for 2 hours in air followed by an air cooling. Then, effects of composition and sintering temperatures on the physical properties such as density, resistivity, magnetic induction, coercive force, initial permeability, and quality factor of the Ni-Zn-Cu ferrite were investigated. The density of the Ni-Zn-Cu ferrite was $4.85\sim5.32g/cm^3$, resistivity revealed $10^8\sim10^{12}\Omega-cm$. The magnetic properties obtained from the aforementioned Ni-Zn-Cu ferrite specimens were 1,300 gauss for the maximum induction, 4.5 oersted for the coercive force, 275 for the initial permeability, and 83 for the quality factor. The physical properties indicated that the specimens could be utilized as the core of high frequency range (involved microwave range) communication and deflection yoke of T.V.

• Journal of IKEEE
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• v.23 no.2
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• pp.599-605
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• 2019

Ferrite cores are used as a soft magnetic material in the fabrication of couplers for inductive powerline communication (PLC). However, it is difficult to adjust the size freely according to the power-line and power-grid environment. In this paper, we report that a nano-crystalline alloy with higher permeability than ferrite can be used as an inductive coupler for non-contact PLC. Since nano-crystalline are produced in the form of a thin ribbon, the size of the coupler can be freely controlled by the number of ribbons wound on the toroidal core. It was fabricated with induction type coupler and showed to be suitable for non-contact power line communication. Experimental results show that the communication bandwidth is 45 Mbps for 100 m and 8 Mbps for 200 m under the current fluctuation of less than 100 A, and the reception ratio is 100%.

• International Journal of Control, Automation, and Systems
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• v.1 no.2
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• pp.215-221
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• 2003

The education system in this paper is used to demonstrate and educate the effects of electromagnetic induction. Placing an aluminum ring over the core and switching on AC source causes the ring to jump in the air due to induced currents in the ring producing a magnetic field opposed to that produced in the core. To control the position of the ring by only the current, it is to require nonlinear control algorithm and control board that is composed of photo sensors, decode circuit, computer communication, and power electronics circuit. This paper provides the development for education system in detail and the effects of dynamic neural networks for nonlinear control with on line is studied.