• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.04c
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• pp.115-118
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• 2008

A field-oriented UHF system for on-line PD monitoring of transformers. is designed, which has been installed inside the oil tank of a transformer by two ways: on-line installing mode through the oil-valve and pre-installing mode through the man hole/hand hole cover. This system has successfully captured long intermittent discharge signals that hadn't been detected through conventional techniques, and solved the problem successfully. The results demonstrate that UHF technique has great advantages for on-line PD monitoring of transformers. By adopting the peak detection technique, it becomes easy and effective for the transplantation of the phase-resolved pattern recognition technique from conventional method to UHF method, and then to realize continuous on-line monitoring, source characterization and trending analysis.

• Journal of Power Electronics
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• v.12 no.4
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• pp.548-558
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• 2012

In this paper, a novel offset-based single-state pulse width modulation (PWM) method for achieving zero common-mode voltage (CMV) and reducing switching losses in multilevel inverters is presented. The specific active switching state of the zero common-mode (ZCM) voltage that approximates the reference voltage can be deduced from the switching state sequence of the reduced CMV phase disposition PWM (CMV PD PWM) method. From the reference leg voltages for the zero common-mode voltage, an N-to-2-level transformation defines a virtual two-level inverter and the corresponding nominal leg voltage references. The commutation process of the reduced CMV PD PWM method in a multilevel inverter and its outputs can be simply followed in a nominal switching time diagram for the virtual inverter. The characteristics of the reduced CMV PD PWM and the single-state PWM for zero common-mode voltage are analyzed in detail in this paper. The theoretical analysis of the proposed PWM method is verified by experimental results.

• Journal of the Microelectronics and Packaging Society
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• v.21 no.3
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• pp.51-56
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• 2014

The reliability of solder joint is significantly affected by the property of surface finish. This paper reports on a study of high speed shear energy and failure mode for Sn-4.0wt%Ag-0.5wt%Cu (SAC405) solder joints with the time of Pd activation. The nodule size of electroless Ni-P deposit increased with increasing the time of Pd activation. The roughness (Ra) of electroless Ni-P deposit decreased with increasing the time of Pd activation. Then, with $HNO_3$ vapor, the quasi-brittle and brittle mode of SAC405 solder joint decreased with increasing the time of Pd activation. This results indicate that the increase in the Pd activation time for Electroless Ni/ Electroless Pd/ Immersion Au (ENEPIG) surface finish play a critical role for improving the robustness of SAC405 solder joint.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.2 no.3
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• pp.439-446
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• 1998

This paper presents design of SD adder and PD adder on Multi-Valued Logic. For implementing of Multi-valued logic circuits we use Current-mode CMOS circuits and also use Voltage-mode CMOS circuits partially. The proposed arithmetic circuits was estimated by SPICE simulation. At the SD(Signed-Digit) number presentation applying Multi-Valued logic the carry propagation is always limited to one position to the left this number presentation allows fast parallel operation. The addition method that add M operands using PD( positive digit number) is effective not only for the realization of the high-speed compact arithmetic circuit, but also for the reduction of the interconnection in the VLSI processor. therefor, if we use PD number representation, the high speed processor can be implementation.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.57 no.2
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• pp.176-180
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• 2008

A field-oriented UHF system for on-line PD monitoring of transformers is designed, which has been installed inside the oil tank of transformer in a substation by two ways: on-line installing mode through the oil-valve and pre-installing mode through the man hole/hand hole cover. This system has successfully captured long intermittent discharge signals that hadn't been detected through conventional techniques, and solved the problem successfully. The results demonstrate that UHF technique has great advantages for on-line PD monitoring of transformers. By adopting the peak detection technique, it becomes easy and effective for the transplantation of the phase-resolved pattern recognition technique from conventional method to UHF method, and then to realize continuous on-line monitoring, source characterization and trending analysis.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.4
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• pp.18-26
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• 2001

In this paper, we propose an ATC(Automatic Transfer mode Controller) algorithm and an average-mode-change method for use in Gear shift PLL which can automatically change loop gain. The proposed ATC algorithm accurately detects proper timing or the mode change and has a very simpler structure - than the conventional lock detector algorithm often used in QPSK. And the proposed average mode change method can obtain low errors of estimated frequency offset by averaging the loop filter output of frequency component in shift register. These algorithms are also useful in designing ASIC, since these algorithms occupy small circuit area and are adaptable for high speed digital processing. We also present phase tracking performance of proposed Gear-shift PLL, which is composed of polarity decision PD, ATC and average mode change circuit, and analyze the results by examining constellation at each mode.

• Analytical Science and Technology
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• v.36 no.4
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• pp.198-203
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• 2023

The reaction of cis-protected (Me4en)Pd(II) species with potentially multidentate bis(benzylthio)methylenepropanedioate (L) was carried out to obtain a monometallic compound, [(Me₄en)Pd(L)], in O,O'-coordination mode. The bis(benzylthio)methylene group was bent strikingly from the palladium square plane at the dihedral angle of 70.40°. The physicochemical properties of the present palladium(II) compound were fully characterized by means of infrared and nuclear magnetic resonance spectroscopy, thermogravimetric analysis, and single-crystal X-ray diffraction measurement.

• Journal of Advanced Navigation Technology
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• v.23 no.2
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• pp.134-141
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• 2019

Radar systems are divided into the pulse Doppler (PD) radar and the frequency modulated continuous wave (FMCW) radar depending on the transmission waveform. In particular, the PD radar is advantageous for long-range target detection, and the FMCW radar is suitable for short-range target detection. In this paper, we present design and implementation results for a multi-mode radar signal processor (RSP) that can support both PD and FMCW radar systems to detect unmanned aerial vehicles (UAVs) at short distances as well as long distances. The proposed radar signal processor can be implemented based on Altera Cyclone-IV FPGA with 19,623 logic elements, 9,759 registers, and 25,190,400 memory bits. The logic elements and registers of the proposed radar signal processor are reduced by approximately 43% and 30%, respectively, compared to the sum of logic elements and registers of the conventional PD radar and FMCW radar signal processor.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.655-658
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• 1995

Magnetization behavior of sputter-deposited Co/Pd multilayers were characterized, and it has been found that even when the multilayers are sputtered at low pressure (10 mTorr), the coercivity of the multilayers can be increased to large extent without noticeable change of saturation magnetization by increasing the deposition pressure of Pd underlayer. It turned out that the surface topology of Pd underlayer gets rough as deposition pressure increases, which consequently affects the magnetization reversal mode of Co/Pd multilayers from domain wall motion to magnetic spin rotation. The enhancement of coercivity is attributed to the domain wall pinning effect which is comected with the surface roughness of Pd underlayer on which Co/Pd multilayers grow.

• ETRI Journal
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• v.38 no.4
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• pp.665-674
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• 2016

We designed and fabricated a semiconductor optical amplifier-integrated dual-mode laser (SOA-DML) as a compact and widely tunable continuous-wave terahertz (CW THz) beat source, and a pin-photodiode (pin-PD) integrated with a log-periodic planar antenna as a CW THz emitter. The SOA-DML chip consists of two distributed feedback lasers, a phase section for a tunable beat source, an amplifier, and a tapered spot-size converter for high output power and fiber-coupling efficiency. The SOA-DML module exhibits an output power of more than 15 dBm and clear four-wave mixing throughout the entire tuning range. Using integrated micro-heaters, we were able to tune the optical beat frequency from 380 GHz to 1,120 GHz. In addition, the effect of benzocyclobutene polymer in the antenna design of a pin-PD was considered. Furthermore, a dual active photodiode (PD) for high output power was designed, resulting in a 1.7-fold increase in efficiency compared with a single active PD at 220 GHz. Finally, herein we successfully show the feasibility of the CW THz system by demonstrating THz frequency-domain spectroscopy of an ${\alpha}$-lactose pellet using the modularized SOA-DML and a PD emitter.