• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.274-277
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• 2000

Power factor and harmonics are increasingly important for high speed train auxiliary block. This paper presents experimental results of the power factor and harmonic performance of four parallel PWM converter circuits under various supply and load conditions. For reducing harmonics the harmonic content is eliminated by the phase shift between four converters switching phase. Experimental results show the usefulness of the proposed method and applicability to PWM converter in auxiliary block of high speed train.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.122-125
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• 1999

The AC-to-DC single-phase PWM rectifier for traction applications using high power semiconductor, IGCT is made and tested. Parallel operation of two PWM converter is adopted for increasing capacity of converters. For reducing harmonics, the harmonic content is eliminated by the phase shift between two converters switching phase. The output voltage control is achieved by interns calculation without detecting the input current. The part of PLL used for controlling power factor is simply implemented by software.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.155-158
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• 2002

Eu-doped lead zirconium titanate $Pb_{1.1}(Zr_{0.3}Ti_{0.7})O_{3}$ thin films on the Pt/Ti/$SiO_2$/Si substrates prepared by a metalorganic decomposition (MOD) method. The effect on the structural and electrical properties of the films measured according to Eu content. Eu-doping altered significantly the dielectric and ferroelectric properties. The remanent polarization and coercive field decreased with increasing the concentration of Eu content. The dielectric constant and dielectric loss of the film decreased with increasing Eu contents. The 3 mol% of Eu-doped PZT thin film showed large remanent polarization and the fatigue characteristic of the film did not change up to $10^9$ switching cycles.

• Journal of the Korean Ceramic Society
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• v.34 no.6
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• pp.569-576
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• 1997

Electrically-induced strain and polarization studies of the (1-x)Pb(Mg1/3Nb2/3)O3-PbZrO3 crystalline solutions have been done. Dielectric constants with temperature were investigated for 0$\leq$x$\leq$0.95. With increasing PbZrO3 content the transition maxima were found to move to higher temperature region and DPT (Diffused Phase Transition) properties were decreased for x$\leq$0.60. Phase transition between ferroelectric states and antiferroelectric states was confirmed for 0.93$\times$10-3 for 0.4

• The Journal of Korea Robotics Society
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• v.17 no.1
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• pp.93-101
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• 2022

Bioheavy oil, which is expanding its range of use as an alternative fuel to reduce environmental pollutant emissions, has a lot of difficulty in combustion due to its low emission of pollutants such as nitrogen oxide (NOx) and sulfur oxide (SOx), while its low dissipation and high oxygen content in fuel. many studies have been conducted on change in characteristics by mixing rate combustion characteristics and combustion reactions, but there have been no specific and effective studies on the composition of control system, optimization of control, development of logic for mixing and burning, minimizing environmental pollutantants discharge. In this study, we intend to consider systemmatic and empirical considerations on the composition, logic development, solve the problem of manual switching of bioler master due to excessive oxygen content and tuning of the control system for optimal combustion of bioheavy oil.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.11
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• pp.1010-1018
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• 2013

The dual-stream based stereoscopic 3D broadcasting standard was developed in 2011. EBS broadcasted 3DTV experimental service according to this standard in April 2012. Dual-stream based 3DTV broadcasting is service-compatible and backward-compatible, so viewers who have legacy 2D HDTV can watch the broadcasting content as 2D. And 3DTV viewers can select watching 2D or 3D. Since 3D content production is not usual yet for terrestrial broadcasters, only some particular programs in specific periods will be broadcasted as 3D at the initiatory stage. For it, stable viewing condition is strongly required for both 2D viewers and 3D viewers. This paper suggests broadcasting transmission system structure and effective switching scheme for stable 2D and 3D viewing conditions in the case of dual-stream based terrestrial 3DTV broadcasting.

• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.179-181
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• 2003

Conventional P/PI speed controller of today's servo drives should be manually tuned the controller switching set-point by trial-and-errors, which may translate the drive system down-time and loss of productivity. The adjustable drive performance is heavily dependent on the qualify of the expert knowledge and becomes inadequate in applications where the operating conditions change in a wide range, i.e., tracking command, cceleration/deceleration time, and load disturbances. In this paper, the demands on simple controls/setup are discussed for industry servo drives. Analyzing the frequency content of motor torque command, P/PI control mode switching is automatically peformed with some prior knowledge of the mechanical dynamics. The dynamic performance of the proposed scheme assures a desired tracking response curve with minimal oscillation and settling time over the whole operating conditions. For comprehensive comparison of traditional P/PI control scheme, extensive test is carried out on actual servo system.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.3
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• pp.233-240
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• 2005

In this paper, AC electric vehicle propulsion system(Converter/Inverter) using high power semiconductor, IPM is proposed. 2-Parallel operation of two PWM converter is adopted for increasing capacity of system and the harmonic content is eliminated by the phase shaft between two PWM converters switching phase. VVVF inverter control is used a mixed control algorithm, where the vector control strategy at low speed region and slip-frequency control strategy at high speed region. The proposed propulsion system is verified by experimental results with a 1,350kW converter and 1,100kVA inverter with four 210kW traction motors.

• Journal of Electrical Engineering and Technology
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• v.2 no.1
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• pp.98-101
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• 2007

Yttrium(Y)-substituted bismuth titanate $(Bi_{4-x},Y_x)Ti_3O_{12}$ [x=0, 0.25, 0.5, 0.75, 1](BYT) thin films were deposited using an RF sputtering method on the $Pt/TiO_2/SiO_2/Si$ substrates. The structural properties and electrical properties of yttrium-substituted $(Bi_4-xYx)Ti_3O_{12}$ thin films were analyzed. The remanent polarization of $(Bi_4-xYx)Ti_3O_{12}$ films increased with increasing Y-content. The $(Bi_{3.25}Y_{0.75})Ti_3O_{12}$ films fabricated using a top Au electrode showed saturated polarization-electric field(P-E) switching curves with a remanent polarization(Pr) of $8{\mu}C/cm^2$ and coercive field (Ec) of 53 kV/cm at an applied voltage of 7 V. The $(Bi_{3.25}Y_{0.75})Ti_3O_{12}$ films exhibited fatigue-free behavior up to $4.5{\times}10^{11}$ read/write switching cycles at a frequency of 1MHz.

• Journal of Power Electronics
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• v.8 no.2
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• pp.171-180
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• 2008

One of the major problems in electric power quality is the harmonic contents. There are several methods of indicating the quantity of harmonic contents. The most widely used measure is the total harmonic distortion (THD). Various switching techniques have been used in static converters to reduce the output harmonic content. This paper presents and compares the two harmonic optimization techniques, known as optimal minimization of the total harmonic distortion (OMTHD) technique and optimized harmonic stepped-waveform (OHSW) technique used in multi-level inverters with unequal dc sources. Both techniques are very effective and efficient for improving the quality of the inverter output voltage. First, we describe briefly the cascaded H-bridge multi-level inverter structure. Then, we present the switching algorithm for the inverter based on OHSW and OMTHD techniques. Finally, the results obtained for the two techniques are analyzed and compared. The results verify the effectiveness of the both techniques in multi-level voltage-source inverter with non-equal dc sources, clarifying the advantages of each technique.