• Title/Summary/Keyword: Phase analysis

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Fault Current Limiting Characteristics of Separated and Integrated Three-Phase Flux-Lock Type SFCLs

  • Lim, Sung-Hun
    • Journal of Electrical Engineering and Technology
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    • v.2 no.3
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    • pp.289-293
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    • 2007
  • The fault current limiting characteristics of the separated and the integrated three-phase flux-lock type superconducting fault current limiters (SFCLs) were analyzed. The three-phase flux-lock type SFCL consisted of three flux-lock reactors and three $high-T_c$ superconducting (HTSC) elements. In the integrated three-phase flux-lock type SFCL, three flux-lock reactors are connected on the same iron core. On the other hand, three flux-lock reactors of the separated three-phase flux-lock type SFCL are connected on three separated iron cores. The integrated three-phase flux-lock type SFCL showed the different fault current limiting characteristics from the separated three-phase flux-lock type SFCL that the fault phase could affect the sound phase, which resulted in quench of the HTSC element in the sound phase. Through the computer simulation applying numerical analysis for its three-phase equivalent circuit, the fault current limiting characteristics of the separated and the integrated three-phase flux-lock type SFCLs according to the ground fault types were compared.

A Study on Kinematic Analysis of Trunk and Lower Extremities in Stance Phase of Walking according to Turning Direction (보행 방향 전환 시 입각기 하지 및 체간의 운동형상학적 분석)

  • Oh, Tae-Young
    • The Journal of Korean Physical Therapy
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    • v.25 no.2
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    • pp.88-95
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    • 2013
  • Purpose: The purpose of this study was to conduct an analysis of kinematics of lower extremities and trunk in stance phase of walking according to turning direction. Methods: Ten university students (five male, five female) who were in their 20s (mean age was 20.6 years old) participated in this study. Participants did not have participants did not have any problem with skeletal muscular system. We used the "Qualisys motion capture system" for analysis of trunk and lower extremity movement in stance phase of walking according to turning direction. We collected data while subjects walked a distance of 10 m, and at the 6 m line, subjects were required to turn to the left side and the right leg was positioned in stance phase and the left leg was positioned in swing. For data analysis, the SPSS for Windows ver. 20.0 statistics program was used in performance of one way analysis of variance according to turning direction. Results: Significant difference of trunk and lower extremities was observed for turning direction according to walking cycle (p<0.05). Upper trunk movement showed a greater increase at three dimensions than lower trunk, and in heel off phase, pelvic movement showed a greater increase than lower trunk (p<0.05). In 45 degree and 90 degrees of turning direction, all movements of trunk and lower extremities were significantly different among three events of stance phase (p<0.05). Conclusion: We suggest that three-dimensional movement analysis of trunk and lower extremities during turning movement was very important in order to indicate increasing balance or walking ability for people with impaired movement or walking.

Experimental Modal Analysis of Two Unequal Rectangular Plates Coupled with Fluid (유체로 연성되고 두께가 상이한 두 직사각 평판의 실험적 모드 해석)

  • Yoo, Gye-Hyoung;Jeong, Kyeong-Hoon;Lee, Seong-Cheol
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.26 no.12
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    • pp.2541-2549
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    • 2002
  • In order to study the vibration characteristics of fluid-structure interaction problem, two rectangular plates coupled with bounded fluid were investigated. Experimental modal analyses were carried out to extract the modal parameters of the system. Additionally. finite element modal analyses performed using a commercial computer code, ANSYS. The FEM solutions were compared with the experimental solutions to verify the finite element model. As a result, the comparison between the experiment and FEM results showed excellent agreement. The transverse vibration modes, in-phase and out-of-phase, were observed alternately in the fluid-coupled system. The thickness effect of the plates on the fluid-coupled natural frequencies and mode shapes was investigated for two different cases with the identical thickness and the unequal thickness. It was found that the coupled natural frequencies increase with the thickness for the identical plates regardless of the mode phase. The experimental and the finite element analysis results showed that the out-of-phase mode shapes were deviated from the symmetrical mode shapes in the plate transverse direction fur the unequal plate thickness case.

Design of a PLL Frequency Synthesizer for RSSI Applications Using Phase Noise Analysis (위상잡음 해석을 이용한 RSSI용 PLL 주파수합성기 설계)

  • Kim, Nam-Tae;Jeong, Jae-Han;Song, Han-Jung
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.48 no.12
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    • pp.28-34
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    • 2011
  • In this paper, a PLL frequency synthesizer for RSSI applications is designed by phase noise analysis. Required synthesizer performance is achieved by optimizing the noise performance of PLL components and a loop transfer function, since its phase noise, lock time, and spur suppression capability are determined by the performance of loop components and loop filter characteristics. As an application example, a PLL frequency synthesizer for RSSI applications, which operates at the frequency of 2.288GHz, is designed using the phase noise analysis. The validity of the design technique is proved by experiments.

Mechanism Analysis and Stabilization of Three-Phase Grid-Inverter Systems Considering Frequency Coupling

  • Wang, Guoning;Du, Xiong;Shi, Ying;Tai, Heng-Ming;Ji, Yongliang
    • Journal of Power Electronics
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    • v.18 no.3
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    • pp.853-862
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    • 2018
  • Frequency coupling in the phase domain is a recently reported phenomenon for phase locked loop (PLL) based three-phase grid-inverter systems. This paper investigates the mechanism and stabilization method for the frequency coupling to the stability of grid-inverter systems. Self and accompanying admittance models are employed to represent the frequency coupling characteristics of the inverter, and a small signal equivalent circuit of a grid-inverter system is set up to reveal the mechanism of the frequency coupling to the system stability. The analysis reveals that the equivalent inverter admittance is changed due to the frequency coupling of the inverter, and the system stability is affected. In the end, retuning the bandwidth of the phase locked loop is presented to stabilize the three-phase grid-inverter system. Experimental results are given to verify the analysis and the stabilization scheme.

N.M.for the Effect of P.T. on Resicual Stress Relaxation (잔류응력 완화에 미치는 상변태의 수치적 모델링)

  • 장경복;손금렬;강성수
    • Journal of Welding and Joining
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    • v.17 no.6
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    • pp.84-89
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    • 1999
  • Most of ferrous b.c.c weld materials may experience martensitic transformation during rapid cooling after welding. It is well known that volume expansion due to the phase transformation could influence on the relaxation of welding residual stress. To apply this effect practically, it is a prerequisite to establish a numerical model which is able to estimate the effect of phase transformation on residual stress relaxation quantitatively. For this purpose, the analysis is carried out in two regions. i.e., heating and cooling, because the variation of material properties following a phase transformation in cooling is different in comparison with the case in heating, even at the same temperature. The variation of material properties following phase transformation is considered by the adjustment of specific heat and thermal expansion coefficient, and the distribution of residual stress in analysis is compared with that of experiment by previous study. consequently, in this study, simplified numerical procedures considering phase transformation, which based on a commercial finite element package was established through comparing with the experimental data of residual stress distribution by other researcher. To consider the phase transformation effect on residual stress relaxation, the transition of mechanical and thermal property such as thermal expansion coefficient and specific heat capacity was found by try and error method in this analysis.

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Concept Analysis of Parents' Treatment Adherence for an Epileptic Child or Adolescent (뇌전증 아동·청소년 부모의 치료이행 개념분석)

  • Lee, Juna;Yoon, Ju Young
    • Research in Community and Public Health Nursing
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    • v.32 no.2
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    • pp.205-219
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    • 2021
  • Purpose: This concept analysis was conducted to clarify 'parents' treatment adherence for an epileptic child or adolescent'. Methods: The analysis used a hybrid model comprising three phases: theoretical phase, fieldwork phase, and integration phase. In the theoretical phase, fifty studies were reviewed. Interviews with four parents of epileptic children or adolescents were conducted during the fieldwork phase. In the integration phase, the results derived from prior phases were synthesized and clarified. All phases were performed cyclically. Results: The concept, 'parents' treatment adherence for an epileptic child or adolescent' was defined as parents' voluntary and goal-directed behavior towards the epilepsy treatment for their children: a collaborative decision-making process with health-care providers, establishing a support system, adaptability to the treatment plans, and appraisals of the child's health condition. Conclusion: This achievement is thought to contribute to improving the accuracy and validity of the concept measurement. It has implications for additional research on how the concept 'treatment adherence' differs in diverse health problems and other population groups than parents of children and adolescents with epilepsy.

Fault Tolerance Operation and Characteristics Analysis of Asymmetric Six-phase Permanent Magnet Synchronous Motor According to Switch Open (비대칭 6상 영구자석 동기 전동기의 스위치 개방에 따른 특성 분석 및 고장허용운전)

  • Jun, So-Young;Hwang, Seon-Hwan;Park, Jong-Won
    • Journal of the Korean Society of Industry Convergence
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    • v.25 no.6_2
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    • pp.1003-1008
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    • 2022
  • This paper proposes a method related to fault tolerance operation and characteristic analysis of asymmetric 6-phase permanent magnet synchronous motor. In general, motor drive systems with multi-phase structures can be continuously operated despite a reduction of power and speed by using a phase changeover or control techniques according to the failures. As a result, it is widely used in industrial fields such as aviation and defense, which require high efficiency and high reliability. In this paper, the second order ripple of the electrical fundamental freuqnecy occurs in the dq-axis currents of the synchronous coordinate system through mathematical analysis according to the switch open of the dual 3-phase inverter. Therefore, the fault tolerant operation method is presented by applying the fault detection method with a constant cycle for continuous operations. The effectiveness of the proposed fault tolerance operation method is verified through the several experiments.

Analysis and Design of Crossover Junctions including Output Phase (출력 위상을 고려한 크로스오버 접합의 해석 및 설계)

  • Myun-Joo Park
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.23 no.1
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    • pp.146-152
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    • 2024
  • This paper presents the analysis and the design methods of the crossover junctions including the output phase. The general solutions were derived analytically through an even-odd analysis of the reflection coefficients and the impedance parameters for the crossover junction with arbitrary output phase. The general solutions were applied to a real crossover junction structure to derive the exact design formula for the arbitrary output phase. The results agreed well with the existing studies. The designed circuit satisfied the crossover junction operation with the exact output phase.