• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.9
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• pp.669-676
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• 2013

In this study, we introduce a polymer(polyimide) based pressure sensor to measure real-time heart beat and blood pressure. The sensor have been designed with consideration of skin compatibility of material, cost effectiveness, manufacturability and wireless detection. The designed sensor was composed of inductor coils and an air-gap capacitor which generate self-resonant frequency when electrical source is applied on the system. The sensor was obtained with metalization, etching, photolithography, polymer adhesive bonding and laser cutting. The fabricated sensor was shaped in circular type with 10mm diameter and 0.45 mm thickness to fit radial artery. Resonant frequencies of the fabricated sensors were in the range of 91~96 MHz on 760 mmHg pressurized environment. Also the sensor has good linearity without any pressure-frequency hysteresis. Sensitivity of the sensor was 145.5 kHz/mmHg and accuracy was less than 2 mmHg. Real-time heart beat measurement was executed with a developed hand-held measurement system. Possibility of real-time blood pressure measurement was showed with simulated artery system. After installation of the sensor on skin above radial artery, simple real blood pressure measurement was performed with 64 mmHg blood pressure variation.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.2
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• pp.203-211
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• 2015

The implanted telemetry system provides the monitoring of species while they move within their cages. Species monitored include mice, rats, rabbits, dogs, pigs, primates, sheep, horses, cattle, and others. A miniature transmitter implanted in each animal measures one or more parameters. Parameters measured include arterial pressure, intra-pleural pressure, left ventricular pressure, intra-ocular pressure, bladder pressure, ECG, EMG, EEG, EOG, temperature, activity, and other parameters and transmits the data via radio frequency signals to a nearby receiver. Every conventional dedicated transmitter contains one or more sensors, cpu and battery. Due to the expected life of battery, the measuring time is limited. To overcome these problems, electromagnetic inductive coupling based wireless power transmission technology using multiple transmit coils were proposed. Each coil having different active area are driven by the coil driver. In this research, parallel resonance based coil driver was proposed. In addition, the device to detect where the receiver is positioned was proposed. From the experiments we show how to determine the driving condition of coil driver.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.6
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• pp.255-261
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• 2005

Recently, the RF inductive discharge or inductively coupled plasma continues to attract growing attention as an effective plasma source in many industrial applications, the best known of which are plasma processing and lighting technology. To the point of lighting sources, the ring-shaped electrodeless fluorescent lamps utilizing an inductively coupled plasma have been objects of interest and research during the last decades, mainly because of their potential for extremely long life, high lamp efficacies, rapid power switching response. In this paper, maxwell 3D finite element analysis program (Ansoft) was used to obtain electromagnetic properties associated with the coil and nearby structures. The electromagnetic emitting properties were presented by 3D simulation software operated at 250 kHz and some specific conditions. The electromagnetic field in the ferrite core was shown to be high and symmetric. An LS-100 luminance meter and a Darsa-2000 spectrum analyzer were used in the experiment. According to data on the lamp tested using high magnetic field ferrite, the optical and thermal wave fields were shown to be high around the ring-shaped electrodeless fluorescent lamp. The optical or light field was high at the center of the bulb rather than around the ferrite core. The light conditions of the bulb were assumed to be complex, depending on the condition of the filler gas, the volume of the bulb, and the frequency of the inverter. Our results have shown coupling between the gas plasma and the field of the light emitted to be nonlinear.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.2
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• pp.149-155
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• 2014

In this paper, we study the complex mobile antenna for WPT(Wireless Power Transfer) with NFC(Near Field Communication) of inductive coupling using FPCB which has half thickness compared with the existing coil type antennas. Considering the pattern thickness of loop antenna, the analysis of electromagnetic wave absorber and battery's influence, absorber thickness, the ranges of design parameters are obtained. The proposed antenna has 0.45 mm thickness using single layer 3 oz FPCB and absorber. From measurement, the characteristics of NFC antenna can be satisfied with the specifications of EMVCo. and domestic mobile telecommunication and the transmission efficiency of the proposed WPT antenna is 68.1 % which is competitive with the existing coil type antenna. From the results of this paper, it has been confirmed that the proposed antenna can be used as the WPT and NFC antenna for mobile phone. Key words: Wireless Power Transfer, Near Field Communication, Mobile Phone Antenna, Absorber, FPCB.

• Journal of electromagnetic engineering and science
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• v.11 no.3
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• pp.166-173
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• 2011

In this paper, we implemented and analyzed a wireless power transfer (WPT) system with a CSPR topology. CSPR refers to constant current source, series resonance circuit topology of a transmitting coil, parallel resonance circuit topology of a receiving coil, and pure resistive loading. The transmitting coil is coupled by a magnetic field to the receiving coil without wire. Although the electromotive force (emf) is small (about 4.5V), the voltage on load resistor is 148V, because a parallel resonance scheme was adopted for the receiving coil. The implemented WPT system is designed to be able to transfer up to 1 kW power and can operate a LED TV. Before the implementation, the EMF reduction mechanism based on the use of ferrite and a metal shield box was confirmed by an EM simulation and we found that the EMF can be suppressed dramatically by using this shield. The operating frequency of the implemented WPT system is 30.7kHz and the air gap between two coils is 150mm. The power transferred to the load resistor is 147W and the real power transfer efficiency is 66.4 %.

• Applied Chemistry for Engineering
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• v.25 no.3
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• pp.254-261
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• 2014

The transformer is a static electrical device that transfers energy by inductive coupling. Then, heat is occurred at coils, inner transformer was filled with insulating oils for cooling and insulation. Although mineral oil as insulating oil has been widely used, it does not meet health and current environmental laws because it is not biodegradable. Therefore, in this study, the diglycerol ester was synthesized with diglycerol and fatty acids (oleic acid and caprylic acid) over various catalysts for insulating oil having biodegradability, high flash points and low pour points. The sulfated zirconia ($SO_4{^{2-}}/ZrO_2$) catalyst prepared at different calcination temperature shows the highest conversion of fatty acids at $600^{\circ}C$ due to crystallinity and high density of acid sites per surface area. When the molar ratio of oleic acid and caprylic acid is 1:3, the diglycerol ester shows superior insulation properties that are the flash point of $306^{\circ}C$ and pour point of $-50^{\circ}C$. The insulation properties of synthesized diglycerol ester shows the pour point of $-50^{\circ}C$ and the flash point of over $300^{\circ}C$. Therefore, diglycerol ester is superior to the vegetable oils in insulation properties.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.12
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• pp.907-914
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• 2018

Wireless charging has been actively researched and popularized owing to the potential convenience of being able to charge electronic devices without wires for users. However, the receiver on the wireless charging pad is not charged when the center of the receiver is misaligned; thus, the center of the receiver must be adjusted well. This misalignment may greatly reduce the convenience of wireless charging. To overcome this limitation of wireless charging, a coil is designed to improve the positional freedom of the receiver. The positional freedom of the Rx coil is improved when the outer diameter of Tx coil is larger than when Rx and Tx coils are almost the same size. When the Tx coil has a larger outer diameter than that of the Rx coil, the efficiency at the center is somewhat lowered, but the efficiency is improved compared to when the center is out of order. In this paper, a double coil structure having an outer and an inner coil is proposed. The double coil structure further improves the efficiency, compared with one coil with the same outer size. The simulation and measurement results demonstrated that the tendency was consistent, and it was verified that the degree of freedom of the Rx coil is improved by adding the inner coil, while the size of the outer coil was the same. The measurement shows that the transmission efficiency of the conventional Tx coil is 37 %, the larger outer diameter coil is 45 %, and double coil is 47 % when the distance of the Tx/Rx coil is 3 mm, the misalignment is 15 mm and current flowing in the Rx coil is 1 A at an operating frequency of 105 to 210 kHz.