• Title/Summary/Keyword: Phase transformation line

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Evolution of the Vortex Melting Line with Irradiation Induced Defects

  • Kwok, Wai-Kwong;L. M. Paulius;Christophe Marcenat;R. J. Olsson;G. Karapetrov
    • 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..

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A Novel Fault Location Method for a Line to Line Fault Using Inverse Theorem of Matrix on Electric Power Lines (행렬의 역정리를 이용한 전력공급 선로의 상간단락 사고지점 검출 방법)

  • Lee Duck-su;Choi Myeon-song;Hyun Seung-ho
    • Proceedings of the KSR Conference
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    • 2004.06a
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    • pp.1321-1324
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    • 2004
  • Unbalanced systems, such as distribution systems, have difficulties in fault locations due to single-phase laterals and loads. In this paper, a novel fault location algorithm is suggested for a line to line faults using inverse theorem of matrix on electric power lines. The fault location for balanced systems has been studied using the current distribution factor, by a conventional symmetrical transformation, but that for unbalanced systems has not been investigated due to their high complexity The proposed algorithms overcome the limit of the conventional algorithm using the conventional symmetrical transformation, which requires the balanced system and are applicable to any electric power system but are particularly useful for unbalanced distribution systems. The simulation results oriented by the real distribution system are presented to show its effectiveness and accuracy.

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A New Line to Line Fault Location Algorithm in Distribution Power Networks using 3 Phase Direct Analysis (3상회로의 직접해석에 의한 송배전계통 선간단락 사고 고장거리 계산 알고리즘)

  • Choe, Myeon-Song;Lee, Seung-Jae;Im, Seong-Il;Jin, Bo-Geon;Lee, Deok-Su
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.51 no.9
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    • pp.467-473
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    • 2002
  • In this paper, a fault location algorithm is suggested for line to line faults in distribution networks. Conventional fault location algorithms use the symmetrical component transformation, a very useful tool for transmission network analysis. However, its application is restricted to balanced network only. Distribution networks are, in general, operated in unbalanced manners, therefore, conventional methods cannot be applied directly, which is the reason why there are few research results on fault location in distribution networks. Especially, the line to line fault is considered as a more difficult subject. The proposed algorithm uses direct 3-phase circuit analysis, which means it can be applied not only to balanced networks but also to unbalanced networks like distribution a network. The comparisons of simulation results between one of conventional methods and the suggested method are presented to show its effectiveness and accuracy.

A New Control Method of Series Active Power Filter with Harmonic Voltage Source (고조파 전압원에 대한 직렬형 능동전력필터의 새로운 제어법)

  • Ko, Soo-Hyun;Shin, Jae-Hwa;Kim, Young-Seok
    • Proceedings of the KIEE Conference
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    • 2002.07b
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    • pp.1033-1036
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    • 2002
  • This paper introduces a control method of series active power filter that compensate harmonic currents and eliminate a neutral line current in 3 phase 3 wire and 3 phase 4 wire power system with harmonic voltage source. These harmonic currents and neutral line current are caused by a nonlinear loads such as diode rectifiers and thyristor converters. Proposed methode extracts a voltage reference directly from performance function without phase transformation. Therefore, the control method is simpler than any other conventional methods. Experimental results for 3-phase 3-wire and 3-phase 4-wire series active power filter system were shown to verify the effectiveness of this control method.

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Implementation of Inverter Systems for DC Power Regeneration

  • Kim Kyung-Won;Yoon In-Sic;Seo Young-Min;Hong Soon-Chan;Yoon Duck-Yong
    • Proceedings of the KIPE Conference
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    • 2001.10a
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    • pp.126-131
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    • 2001
  • This paper deals with implementation of inverter systems for DC power regeneration, which can regenerate the excessive DC power from DC bus line to AC supply in substations for traction systems. From the viewpoint of both power capacity and switching losses, a three-phase square-wave inverter system is adopted. To control the regenerated power, the magnitude and phase of fundamental output voltages should be appropriately controlled in spite of the variation of input DC voltage. Inverters are operated with modified a-conduction mode to fix the potential of each arm. The overall system consists of the line-to-line voltage and line current sensors, an actual power calculator using d-q transformation method, a complex power controller with PI control scheme, a gating signal generator for modified $\alpha-conduction\;mode\;with\;\delta\;and\;\alpha$, a DPLL for frequency followup, and power circuit.

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An Experimental Study of Reconstruction from Laser Diffraction Measurement for Axisymmetric Sprays (레이저 회절법을 이용한 축대칭 분무 구조의 공간 분포 변환에 관한 실험적 연구)

  • 양승연;이충훈;구자예;정석호
    • Transactions of the Korean Society of Automotive Engineers
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    • v.8 no.1
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    • pp.10-16
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    • 2000
  • Spatially resolved liquid volume fractions from a set of line-of-sight laser diffraction measurements for axisymmetric sprays generated from a pintle-type gasoline injector have been tomographically reconstructed by Abel transformation, Fourier transformation and onion peeling method. Spatially resolved liquid volume fractions classified into 32 size groups were translated characteristics of SI engine fuel sprays. These data were also obtained from the phase Doppler measurements for the same sprays. The comparison between laser deffraction measurements and transformation reconstructs more reasonable spatially resolved characteristics for axisymmetric sprays as well as for asymmetric sprays.

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Design of a Miniaturized 5.3 GHz 360° Analog Phase Shifter (소형화된 5.3 GHz 대역 360° 아날로그 위상천이기 설계)

  • Jeong, Hae-Chang;Son, Bon-Ik;Lee, Dong-Hyun;Ahmed, Abdul-Rahman;Yeom, Kyung-Whan
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.24 no.6
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    • pp.602-612
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    • 2013
  • In this paper, a design and fabrication of miniaturized 5.3 GHz reflection type $360^{\circ}$ analog phase shifter with branch line coupler and $360^{\circ}$ variable reactance load. In order to miniaturize phase shifter, novel branch line coupler is proposed. The novel branch line coupler is miniaturized using transformation of transmission line to T and ${\pi}$ type equivalent circuit. The miniaturized branch line coupler has small size of above 50 % compared with conventional branch line coupler. For wide phase shift range, $360^{\circ}$ variable reactance load structure is adopted. Especially, the structure was improved for linear phase shift by adding transmission line which acts as an impedance transformer. The improved structure was miniaturized using the equivalent lumped-element of transmission line. The fabricated phase shifter with $15{\times}15mm^2$ shows wide phase shift of above $480^{\circ}$, the insertion loss of -4~-6 dB and the reflection loss of below -20 dB at 5.3 GHz under 0~10 V control voltage range.

Characteristics of Zn-Ni Electrodeposition of 60 kgf/$\textrm{mm}^2$ Grade Transformation Induced Plastic Steel Sheets for Automotive Body (60 kgf/$\textrm{mm}^2$급 자동차용 변태유기소성강화강 Zn-Ni 전기도금 특성 연구)

  • Kim D. H.;Kim B. I.;Jeon Y. T.;Jeong Y. S.
    • Journal of the Korean institute of surface engineering
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    • v.37 no.5
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    • pp.263-272
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    • 2004
  • High strength steels such as transformation induced plastic steel, dual phase and solid solution Hardening have been developed and continuously improved due to the intensified needs in the automotive industry. But silicon and manganese in transformation induced plastic steels were known to exhibit harmful effects on galvannealing reaction by oxide film formed during heat treatment. Therefore, in this work, the applicability of Zn-Ni electrodeposition instead of hot dip galvannealed coating to transformation induced plastic steels was evaluated and optimum electroplating condition was investigated. Based on these investigations optimized electroplating conditions were proposed and Zn-Ni electrogalvanized steel sheet was produced by EGL (electrogalvanized line). Its perfomance properties for automotive steel was evaluated.

A new line to line fault location algorithm in distribution power networks using 3 phase direct analysis (3상회로의 직접해석에 의한 배전계통 선간단락 사고 고장거리 계산 알고리즘)

  • Jin, B.G.;Choi, M.S.;Lee, S.J.;Yoon, N.S.;Jung, B.T.;Lee, D.S.
    • Proceedings of the KIEE Conference
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    • 2002.07a
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    • pp.108-110
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    • 2002
  • In this paper, a fault location algorithm is suggested for line to line faults in distribution networks. Conventional fault location algorithms use the symmetrical component transformation, a very useful tool for transmission network analysis. However, its application is restricted to balanced network only. Distribution networks are, in general, operated in unbalanced manners, therefore, conventional methods cannot be applied directly, which is the reason why there are few research results on fault location in distribution networks. Especially, the line to line fault is considered as a more difficult subject. The proposed algorithm uses direct 3-phase circuit analysis, which means it can be applied not only to balanced networks but also to unbalanced networks like distribution a network. The comparisons of simulation results between one of conventional methods and the suggested method are presented to show its effectiveness and accuracy.

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Simulation of plate deformation due to line heating considering water cooling effects (수냉 효과를 고려한 선상가열에 의한 판 변형의 시뮬레이션)

  • Ko, Dae-Eun;Ha, Yun-Sok
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.12 no.6
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    • pp.2470-2476
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    • 2011
  • Inherent strain method, a hybrid method of experimental and numerical, is known to be very efficient in predicting the plate deformation due to line heating. For the simulation of deformation using inherent strain method, it is important to determine the magnitude and the region of inherent strain properly. Because the phase of steel transforms differently depending on the actual speed of cooling following line heating, it should be also considered in determining the inherent strain. A heat transfer analysis method including the effects of impinging water jet, film boiling, and radiation is proposed to simulate the water cooling process widely used in shipyards. From the above simulation it is possible to obtain the actual speed of cooling and volume percentage of each phase in the inherent strain region of a line heated steel plate. Based on the material properties calculated from the volume percentage of each phase, it should be possible to predict the plate deformations due to line heating with better precision.