• Proceedings of the KIEE Conference
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• 2006.07d
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• pp.2009-2010
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• 2006

This paper presents an adaptive line coupler to match input impedance of the Power line Communication(PLC) modem between access impedance of the power line. This line coupler provides maximum signal power transmiting capability, high reliability. The structure of this coupler is simple and designed to make a easy and low cost. The proposed line coupler is suitable for Amplitude Shift Keying(ASK) or Phase Shift Keying(PSK) modem. To figure out our models, the analysis of the transmitting features of power line channel is performed in the time domain at the carrier frequency. As a result of this study, we present the values of capacitors in the capacitor bank and adaptive line coupler circuit.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.1 s.104
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• pp.1-7
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• 2006

New phase shifters with higher phase shift values are presented using defected ground structures(DGSs). The varactor diodes are mounted on DGSs of termination loads to control the large phase variation of the DGS at resonance. Two types of phase shifters are implemented with a branch-line and a coupled line hybrid. The experimental results of the proposed phase shifters show $135\%$ and $221\%$ increases in maximum phase shills, respectively, compared with those of conventional ones.

• Journal of Welding and Joining
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• v.9 no.4
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• pp.60-68
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• 1991

The weld quality of end cap welds in Pressurized Heavy Water Reactor (PHWR) Fuel is extremely important for the fuel performance in the nuclear reactor. The quality of resistance upset welds is currently evaluated mainly by the metallographic examination although it reveals only two weld cross-sections in a circumference welds. This investigation was, firstly, carried out to determine whether the ultrasonic examination would be applied to detect weld defects in the end cap welds and, secondly, to measure the mechanical strength of upset butt welds as a function of phase shift percentage. The major results obtained in this study are as follows: 1. The weld current and amount of upset shrinkage linearly increased with increasing the phase shift percentage. 2. Above the phase shift 55%, the defects in the welds were completely eliminated with increasing the phase of sound weld was over the thickness of cladding tube. 3. The ultrasonic testing well detected such defects in the end cap welds as upset external crack, upset split, corner crack and irregular weld flash comparing with the results of metallography. 4. The micro-fissure in the corner of the end cap welds was reliably detected by ultrasonic testing. 5. The mechanical strength in the welds increased with increasing phase shift percentage but the fracture did't occur in the welds above 55%.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.468-469
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• 2010

DSTATCOM(Distribution STATic COMpensator) is one of the custom power devices, and protects a distribution line from unbalanced and harmonic current caused by non-linear and unbalanced loads. Conventional researches use a LPF(Low Pass Filter) to eliminate ripple component at the calculation of compensation current. This paper proposes a calculation of compensation current using phase shift that can be a counterproposal of conventional methods using LPF.

• KIEE International Transactions on Electrophysics and Applications
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• v.5C no.3
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• pp.131-137
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• 2005

This paper describes a new approach to the algorithm and fundamental characteristics of the device for monitoring the leakage currents flowing through zinc oxide (ZnO) surge arresters. In order to obtain a technique for a new on-line monitoring device that can be used in the deterioration diagnosis of ZnO surge arresters, the new algorithm and on-line leakage current detection device for extracting the resistive and capacitive currents using the phase shift addition method were proposed. The computer-based on-line monitoring device can sense accurately the power frequency leakage currents flowing through ZnO surge arresters. The on-line leakage current monitoring device of ZnO surge arresters proposed in this work has the high sensitivity compared to the third harmonic leakage current detection devices. As a consequence, it was found that the proposed leakage current monitoring device would be useful for forecasting the defects and degradation of ZnO surge arresters.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.9
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• pp.1048-1057
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• 2012

In this paper, a new compact dual-band unequal power divider is suggested. Instead of the quarter wavelength transmission line(TX-line)s for the branches of the conventional Wilkinson's power divider, we use composite right- and left-handed(CRLH) phase-shift lines and can reduce the physical length. With the non-linear dispersion of the meta-meterial, each branch in the proposed divider is designed to have $+90^{\circ}$ and $-90^{\circ}$ at $f_1$ and $f_2$ respectively. To validate the proposed method, the performances of the circuit and full-wave simulation results are shown with the CRLH dispersion curve. The measurement results are compared with the simulation results. Also, the size reduction effect by the proposed scheme is addressed.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.61 no.3
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• pp.111-115
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• 2012

Generally, brushless DC motor(BLDCM) driving system uses hall sensors or encoders as the mechanical position or speed sensor. It is necessary to achieve the informations of rotor position for driving trapezoidal type brushless DC motor without any position sensor. In this paper, the commutation signals are obtained without the motor neutral voltage, multistage analog filters, A/D converters, or the complex digital phase shift circuits which are indispensable in the conventional sensorless control algorithms. In the proposed method, in stead of detecting the zero crossing point of the nonexcited motor back electromagnetic force for the average motor terminal to neutral voltage, the commutation signal are extracted directly from the specific average line to line voltage with low-pass filter, adder and comparators circuit. In contrast to conventional methods, the neutral voltage is not need; therefore, the commutation signals are insensitive to the common mode noise. Moreover, the complex phase shift circuit can be eliminated. The effectiveness of the proposed method is verified through simulation results.

• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.3
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• pp.408-412
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• 1987

The designing method of the reflection and the loaded-line phase shifter is presented. Its phase shift is variable with changing of the stub parameters. In this paper, we design the 2-bit phase shifter which have 10\ulcornerand 90\ulcornerbit phase shift and analysi its characteristics. The experiments show 2d B max.insertion loss, 2.0max. input VSWR and 6\ulcornerphase error on 2.9-3.1GHz frequency range. They agree well with the theoretical results.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.215-218
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• 2002

In this paper, we propose a microstrip line tunable phase shifter. If we vary the applied bias voltage, the relative dielectric constant of ferroelectrics also changes and we designed tunable phase shifter using Au/BSTO/MgO/Au structure. We also used a coupling structure to increase the amount of phase shift at certain frequency in a limited size and we could reduce the loss by reducing the line width.

• Progress in Superconductivity
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• v.3 no.1
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• pp.5-12
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• 2001

Our experimental research focuses on manipulating pinning deflects to alter the phase diagram of vortex matter, creating new vortex phases. Vortex matter offers a unique opportunity for creating and studying these novel phase transitions through precise control of thermal, pinning and elastic energies. The vortex melting transition in untwinned YB $a_2$C $u_3$ $O_{7-}$ $\delta$/ crystals is investigated in the presence of disorder induced by particle irradiation. We focus on the low disorder regime, where a glassy state and a lattice state can be realized in the same phase diagram. We follow the evolution of the first order vortex melting transition line into a continuous transition line as disorder is increased by irradiation. The transformation is marked by an upward shift in the lower critical point on the melting line. With columnar deflects induced by heavy ion irradiation, we find a second order Bose glass transition line separating the vortex liquid from a Bose glass below the lower critical point. Furthermore, we find an upper threshold of columnar defect concentration beyond which the lower critical point and the first order melting line disappear together. With point deflect clusters induced by proton irradiation, we find evidence for a continuous thermodynamic transition below the lower critical point..