• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.04a
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• pp.493-499
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• 1997

In this study, the changes in transmitting and receiving characteristics, especially resonance frequencies, of the underwater acoustic planar array transducer by the transformers used in the analog weighting circuit are investigated. Electrical equivalent circuit analysis shows that an ideal transformer does not change the resonance frequency of the transmitting mode, but the resonance frequency which gives the maximum receiving sensitivity can be designed by adjusting the magnitude of reactance of transformer.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.2
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• pp.213-218
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• 2022

In this paper, a technology for a high-efficiency wireless power transmission transmitting and receiving coil that can wirelessly charge a drone is introduced. The drone station implements the ability to charge the battery wirelessly without the need to remove the battery to charge the drone's battery. In order to charge the drone's battery in the shortest time, wireless charging efficiency must be high. In order to increase the wireless charging efficiency of the drone station, a method for manufacturing high-efficiency transmitting and receiving coils and a performance measurement method are presented. Transmitting and receiving coils were manufactured considering the size and weight of the drone so as not to interfere with the flight of the drone. Efficiency of 88% or more was realized at a distance of 40mm or more between the transmitting and receiving coils.

• 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 %.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.14 no.1
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• pp.48-55
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• 2021

The 3-coil magnetic resonance wireless power transmission system was analyzed using an equivalent circuit model, and the |S21| of the system was expressed as the equation of the Q of the three coils, the coupling coefficient k between the transmitting coil and the relay coil, the relay coil and the receiving coil. It is suggested that the maximum efficiency can be obtained when the relay coil is located in the center of the transmitting and the receiving coil. When the distance between the transmitting and the receiving coil is 30 cm and the two coils are aligned, maximum efficiency of 9 % is obtained with the relay coil centered between the coils. If the transmitting coil and the receiving coil are misaligned during a wireless charging of an electric vehicle, the efficiency is expected to decrease significantly compared to the aligned case. It is expected that the efficiency can be increased by using a relay coil and by rotating the coil.

• The Journal of the Acoustical Society of Korea
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• v.20 no.3
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• pp.83-90
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• 2001

Conventional SAW duplexer filters employ a 1/4 wavelength transmission line, which causes difficulty in fabrication of the strip line on the package. Its manufacturing process is also complicated, because it needs integrating process of the separate transmitting filter, receiving filter and isolation circuits. This paper concerns development of a new structure of the duplexer filter that has all the transmitting filter, the receiving filter and the isolation circuit as a one chip device. For composition of the duplexer, we design the component SAW ladder filters and the isolation network consisting of lumped inductor and capacitor elements. Performance of the whole duplexer is optimized by the nonlinear multivariable minimization of a proper target function, and the result is compared with that of commercial filters.

• Journal of IKEEE
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• v.23 no.1
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• pp.306-309
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• 2019

Wireless charging is a technology of transmitting power through an air gap to an electrical load for the purpose of energy dissemination. Compared to traditional charging with code, wireless power charging has many benefits of avoiding the hassle from connecting cables, rendering the design and fabrication of much smaller devices without the attachment of batteries, providing flexibility for devices, and enhancing energy efficiency, etc. A transmitting coil and a receiving coil for inductive coupling or magnetic resonant coupling methods are available for the near field techniques, but are not for the far field one. In this paper, the wireless power transfer (WPT) circuit by using magnetic resonant coupling method with a resonant frequency of 13.45 Mhz for the low power system is implemented to measure the power transmission efficiency in terms of mutual distance and omnidirectional angles of receiver.

• 전자공학회논문지 IE
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• v.44 no.4
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• pp.30-34
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• 2007

The Channel environment is poor in the power line communication because power line proposed power supply use a communication medium. In this paper, we designed gate drive circuit used coupler reducing the signal diminution for the good communication. We analyzed receiving and transmitting operation of the coupler and designed the drive circuit with the suitable impedance. As a result, we improved the environment of impedance variation due to the inter reaction of many electron products. So, to improve BER(45%) enabled us to communicate smoothly in power line communication.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.13 no.2
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• pp.160-170
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• 1988

This paper describes the outboard NIU(Network Interface Unit) using microprocessor and the hardware and software of concentrator for constructing star typed LAN(Local Area Network) based on token ring method. The NIU adapter can adapter up to four parallel and serial typed terminals. Because it has PAD function on input output data, any type of terminals can be adapted. Since the concentrator has logical switching circuit which enables data to bypass the faulted NIU adapter, this network prevents communication break. When user transmits and receives data, the concentrator constructs star typed LAN which connct both transmitting and receiving sides. A s result, this network eliminated ring latency time in other NIU exculding transmitting and receiving NIU. So the throughput of this LAN is increased. Because this LAN system consists of several modultes according to it's function, the expansion of function or the modification of method is easy.

• Journal of Veterinary Clinics
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• v.13 no.2
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• pp.171-176
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• 1996

In this study, dldctronic identification system of individual dairy cow was developed for autocatization of stoxkvreeding management. To automize the breeding management, it is necessary to obtain and analyze the individual information distinguished from others perferentially. Electronic identification system can distinguish individual livestock from others with electromagnetic wave signal recognition system. Electoronic identification system consists of transmitter transmitting the oscillated signal and receiver set. The transmitted signal from transmitter clung to individual livestock is received from the receiving antenna and the signal in different according to the established value of the register. By distinct signal recieved from the reciever, wi can distinguish the identity of a livestock from others clearly. This system can manage $2^{12}$ individuals with a reciever theoretically. However in order to reduce the errors by analogous signal, this system uses only triple number and can manage 1365 individuals with a reciever practically. This system can be connevtted to Max 232 and microcomputer for the breeding management efficiently.

• The Journal of the Acoustical Society of Korea
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• v.15 no.4
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• pp.77-82
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• 1996

In this paper an identification method is presented to obtain the equivalent electric model of a sandwitch type piezoelectric transducer. Unknown parameters related to the equivalent circuit are identified by solving a nonlinear optimization problem which can minimize an error between the experimental and analytical admittances in air. The proposed method is applied to an example transducer. The validity of equivalent circuit model is demonstrated by the comparison between the experimental measurements and analytical calculations of transmitting voltage response(TVR) and receiving voltage response(RVS).