• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.100-103
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• 2003

In this paper, the characteristics of an inverted-F antenna for the 2.4GHz local wireless communication system have been analysed in terms of the variation of design parameters. The antenna can be integrated on printed circuit board, and the characteristics in terms of the variation of the gap between feed line and shorting stub, gap between antenna's leg and ground plane, antenna leg's width, substrate's height and dielectric constant are analysed. By using these characterization plot of design parameter, the tuning techniques are proposed to design optimum antenna. The designed antenna has 6.4% frequency bandwidth for VSWR under 1.5 and 3dB gain.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.6
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• pp.1103-1108
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• 2003

In this paper, the characteristics of an inverted-F antenna for the 2.4GHz local wireless communication system have been analysed in terms of the variation of design parameters. The antenna can be integrated on printed circuit board, and the characteristics in terms of the variation of the gap between feed line and shorting stub, gap between antenna's leg and ground plane, antenna leg's width, substrate's height and dielectric constant are analysed. By using these characterization plot of design parameter, the tuning techniques are proposed to design optimum antenna. The designed antenna has 6.4 % frequency bandwidth for VSWR under 1.5 and 3dB gain.

• Journal of the Korean Society of Visualization
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• v.14 no.2
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• pp.52-60
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• 2016

The Passive Auxiliary Feedwater System(PAFS) is one of the advanced safety concepts adopted in the Advanced Power Reactor Plus(APR+). To validate the operational performance of the PAFS, detailed understanding of a boiling heat transfer on horizontal tube outside is of great importance. Especially, in the mechanistic boiling heat transfer model, it is important to visualize the phenomena but there are some limitations with conventional experimental approaches. In the present study, we devised a heater based on the Flexible Printed Circuit Board (FPCB) for a more comprehensive visualization and subsequently, a digital image processing technique for the bubble motion measurement was established. Using the measurement technique, important parameters of the nucleate boiling are analyzed.

• Journal of Navigation and Port Research
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• v.28 no.1
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• pp.31-36
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• 2004

In this paper, the characteristics of an inverted-F antenna for the 2.4GHz(ISM) Bluetooth system have been analysed in terms of the variation of design parameters. The antenna can be integrated on printed circuit board, and the characteristics in terms of the variation of the gap between feed line and shorting stub, gap between antenna's leg and ground plane, antenna leg's width, substrate's height and dielectric constant are analysed By using these characterization plot of design parameter, the tuning techniques are proposed to design optimum antenna. The designed antenna has 6.3%(150MHz) frequency bandwidth for VSWR under 1.5, and 3dBi gain.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.8
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• pp.1-7
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• 1998

This paper reports a dispersion compensation technique to implement tje distortionless transmission line by satisfying the heaviside conditon. Because of the skin depth for aconductor, compensation condition is dependent on the freuqncy variation. For this reason, first, the resistance have been chaacterized in awide range of frequencies, and then found the effective conductivity of the substrate which satisfied the heaviside condition. The phase velocity and the characteristics impedance are prresented nearly constant over a wideband frequency range.

• Journal of the Korean Graphic Arts Communication Society
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• v.15 no.2
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• pp.15-24
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• 1997

In DTP systems, satisfactory matching the appearance of displayed image on CRT and that of a reproduced binary image is very important. Most halftoning techniques assume that the printed color dots are square. However, most printers produce roughly circular dots. Thus, there is overlap between adjacent dots, and dots accupy adjcent space that should be empty space. These results are because the significant image distortion on the reproduced images. In this paper, we proposed a new tone correction digital halftoning method based on equi-visual perception characteristic.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.10
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• pp.907-913
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• 2015

This work presents a method to predict the near magnetic field distribution on the digital switching circuit mounted on PCB using co-simulation of circuit and electromagnetic fields. The proposed method first obtains the normalized near field distribution by exciting the signal and power ports of the switching circuit using sinusoidal sources. Then the real near magnetic field distribution is determined by weighting the normalized field distribution using the current spectrum of the switching circuit. To confirm the proposed method, a switching IC with a ring oscillator and a output buffer is fabricated and measured in the form of chip-on-board. The surface magnetic field distribution is measured using a magnetic probe above the PCB and compared with the simulation results. Experimental results show the correspondence between simulation and measurement results within 10 dB up to fifth harmonics.

• Journal of Power Electronics
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• v.15 no.3
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• pp.644-651
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• 2015

This paper introduces a novel digital one cycle control (DOCC) boost power factor correction (PFC) converter. The proposed PFC converter realizes the FPGA-based DOCC control approach for single-phase PFC rectifiers without input voltage sensing or a complicated two-loop compensation design. It can also achieve a high power factor and the operation of low harmonic input current ingredients over universal loads in continuous conduction mode. The trailing triangle modulation adopted in this approach makes the acquisition of the average input current an easy process. The controller implementation is based on a boost topology power circuit with low speed, low-resolution A/D converters, and economical FPGA development board. Experimental results demonstrate that the proposed PFC rectifier can obtain a PF value of up to 0.999 and a minimum THD of at least 1.9% using a 120W prototype.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.389-392
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• 2003

A use of micro processor having H-com functions is gradually increased, and this paper describes the digital servo controller applied to linear pulse motor The TMS320LF2407, made by TI(Texas Instruments Co.), is used as a arithmetic unit in control circuit, designed f3r motor drive and available for the implement of high performance and miniaturization. Also, it can allow the sufficient debugging and downloading into control board for independent operation. A current control in order to carry out a position control is of a digital current control mode, and its implement confirmed the servo control performance of position control.

• Journal of Engineering Education Research
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• v.6 no.2
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• pp.5-14
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• 2003

In this paper, we developed an efficient virtual experiment kit with creative and interactive multimedia contents, which can be used to enhance the quality of education in the area of digital logic circuits. Since our virtual experiment kit is implemented to describe the on-campus laboratory, the learners can obtain similar experimental data through it. Also, our web-based virtual experiment kit is designed to enhance the efficiency of both the learners and the educators. The learners will be able to achieve high learning standard and the educators save time and labor. The virtual experiment is performed according to the following procedure: (1) Circuit Composition on the Bread Board (2) Applying Input Voltage (3) Output Measurements (4) Checkout of Experiment Results. Furthermore, the circuit composition on the bread board and its corresponding online schematic diagram are displayed together on the virtual experiment kit for the learner's convenience. Finally, we have obtained several affirmative effects such as reducing the total experimental hours and the damage rate for experimental equipments and increasing learning efficiencies as well as faculty productivity.