• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.45-48
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• 2000

By the use of he DSP and microprocessor controller many high power converter such as especially inverter and motor drive system may be enhanced resulting in the improved robustness of EMI the ability to communicate the operating conditions and the ease of adjusting the control parameters. However the digital controller using DSP or microprocessor has not been applied in the high frequency switching power supplies especially in full bridge dc/dc converters. this paper presents a promising solution to the dc bias control problem of high frequency transformer in high power full bridge converter.

• Proceedings of the IEEK Conference
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• 2003.07b
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• pp.695-698
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• 2003

This paper presents a Si power LDMOSFET for power amplifiers in the 1.8-2.2GHz frequency range for the base station of personal communication systems. To improve the cut-off frequency, the proposed Si power LDMOSFET has small gate to drain capacitance by shielding the electric fields with extended source electrode and forming the field oxide structure in drain region. The proposed Si power LDMOSFET can be used for a power amplifier and it has 32% of power added efficiency and 39.5dBm of output power when the supply voltage is 28V and the operating frequency is 1.9GHz.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1999.11a
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• pp.189-194
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• 1999

This paper proposes a current-fed type high frequency inverter using a soft switching technology Zero-Voltage-Switching to reduce turn on and off loss at the switching. The analysis of the proposed circuit was described by using normalized parameter and operating characteristics have been evaluated as to switching frequency and parameters. The theoretical results are in good agreement with the experimental ones. In the future the proposed circuit is considered to be useful for induction heating applications.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2001.06a
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• pp.25-28
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• 2001

A new decision-feedback equalization technique for a filter bank-based orthogonal frequency division multiplexing (OFDM) data transmission system operating in a frequency selective multipath fading channel is presented in this paper. At the cost of relatively increased computational complexity in comparison to the conventional OFDM systems, the proposed system achieves a better performance in terms of bit error rates. The simulation results confirm the superiority and robustness of our method, particularly, in the low SNR channel environment.

• Journal of IKEEE
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• v.10 no.2 s.19
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• pp.128-133
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• 2006

This paper describes a high speed interface circuit using redundant multi-valued logic for high speed communication ICs. This circuit is composed of encoding circuit that serial binary data are received and converted into parallel redundant multi-valued data, and decoding circuit that converts redundant multi-valued data to parallel binary data. Because of the multi-valued data conversion, this circuit makes it possible to achieve higher operating speeds than that of a conventional binary logic. Using this logic, the proposed 1:4 DEMUX (demultiplexer, serial-parallel converter), was designed using a 0.35um standard CMOS technology. Proposed DEMUX is achieved an operating speed of 4.5Gb/s with a supply voltage of 3.3V and with power consumption of 53mW. The operating speed of this circuit is limited by the maximum frequency which the 0.35um process has. Therefore, this circuit is to achieve CMOS communication ICs with an operating speed greater than 10Gb/s in submicron process of high operating frequency.

• Nuclear Engineering and Technology
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• v.47 no.6
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• pp.729-737
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• 2015

Wireless communication technologies, especially smartphones, have become increasingly common. Wireless technology is widely used in general industry and this trend is also expected to grow with the development of wireless technology. However, wireless technology is not currently applied in any domestic operating nuclear power plants (NPPs) because of the highest priority of the safety policy. Wireless technology is required in operating NPPs, however, in order to improve the emergency responses and work efficiency of the operators and maintenance personnel during its operation. The wired telephone network in domestic NPPs can be simply connected to a wireless local area network to use wireless devices. This design change can improve the ability of the operators and personnel to respond to an emergency situation by using important equipment for a safe shutdown. IEEE 802.11 smartphones (Wi-Fi standard), Internet Protocol (IP) phones, personal digital assistant (PDA) for field work, notebooks used with web cameras, and remote site monitoring tablet PCs for on-site testing may be considered as wireless devices that can be used in domestic operating NPPs. Despite its advantages, wireless technology has only been used during the overhaul period in Korean NPPs due to the electromagnetic influence of sensitive equipment and cyber security problems. This paper presents the electromagnetic verification results from major sensitive equipment after using wireless devices in domestic operating NPPs. It also provides a solution for electromagnetic interference/radio frequency interference (EMI/RFI) from portable and fixed wireless devices with a Wi-Fi communication environment within domestic NPPs.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.2
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• pp.122-129
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• 2009

Frequency is an important operating parameter of a power system. It is essential that the frequency of a power system be maintained very close to its nominal frequency. And frequency measurement devices have need to measure a fast and accurate of frequency using voltage signals. This paper proposes a comparative study of frequency estimation techniques using the high speed FIR filter based algorithm, the DFT filter based algorithm using phasor angle between two phasors, and positive sequence component based algorithm using the half angle between two successive positions of phasor. The discussed three techniques have been formed through numerical manipulation of a discrete system. The proposed techniques have been tested using signals obtained from selected power system model using ATP simulation package. Some test results are shown in this paper.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.6
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• pp.68-74
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• 2013

Induction-heated system is innovative system which applied IH(Induction Heating) magnetic induction heating generated from induction-heated metallic package and high-frequency power circuit technique for thermal converse technique. In this occurs not burning, so that the working environment and deterioration of products can be improved. This technique is used high frequency inverter. By using high frequency inverter high frequency in the range of kHz can be made with conventional alternative current. In this contribution IGBT module is used for high frequency inverter. In this paper are discussed analysis of characteristics according to the each frequency and produced Flat plate induction heating system using 1.5kW-class half-bridge resonant inverter. In addition, operating characteristics of the system to changes in the distance between the coil and the heater, applications of system are also discussed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.5
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• pp.866-874
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• 2008

Motor frequency can be measured by a hall sensor. Among the many hall sensors, a linear type hall sensor is good at high accuracy frequency measuring problem. However, in general, this linear type hall sensor has DC offset which can vary along sensor's operating voltage change. Therefore, In motor frequency measurement problem using the linear hall sensor, it needs an estimator that can estimate frequency and DC offset simultaneously. In this paper, we propose the least mean square estimator to estimate motor frequency. To verify its performance, we compare the LMS estimator with a commercial analog tachometer. Experimental results shows the proposed LMS estimator works well in varying frequency and stationary DC offset.

• The Journal of the Acoustical Society of Korea
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• v.43 no.1
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• pp.39-48
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• 2024

A car horn serves a crucial safety role as a means of communication between drivers and a part that alerts pedestrians in advance. While previous studies have utilized finite element method and electric circuit model to simulate and analyze characteristics of the car horns, there remains a lack of research on design methods of a trumpet horn. This paper presents a design approach that predicts the operating frequency based on the acoustic reactance at the throat of the horn, once the vibrating part is determined. We deal with a horn combining both an exponential horn and a waveguide in the acoustic section, and confirm that the acoustic reactance at the horn throat measured by impedance tube experiment agrees well compared with the numerical result obtained using the finite element method. The resonance frequency of the car horn is predicted using the COMSOL Multiphysics finite element numerical analysis model, and the proposed design method is validated by measuring the operating frequency of the designed horn in a sound pressure experiment. As a result, the resonance measured in a semi-anechoic chamber environment by applying a DC voltage of 12 [V] excluding the holder occurs accurately within a few [Hz] of the design operating frequency. This paper discuss the design method of a trumpet horn from the perspective of the horn's acoustic reactance, and is expected to be useful for designing horn systems.