• Title/Summary/Keyword: residual phase

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Dispersion Management and Optical Phase Conjugation in Optical Transmission Links with a Randomly Distributed Single-Mode Fiber Length

  • Lee, Seong-Real
    • Journal of information and communication convergence engineering
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    • v.11 no.1
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    • pp.1-6
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    • 2013
  • Suppressing or mitigating signal distortion due to group velocity dispersion and optical Kerr effects is necessary in ultra-high speed and long-haul wavelength division multiplexing (WDM) transmission systems. Dispersion management (DM), optical phase conjugation (OPC), and the combination of these two are promising techniques to compensate for signal distortion. In this paper, to implement a flexible optical WDM network, a new optical link configuration with a randomly distributed single-mode fiber (SMF) length and fixed residual dispersion per span in the combination of DM and OPC is proposed and investigated. The simulation results show that the best net residual dispersion (NRD) in the proposed optical links is +10 ps/nm, which is independent of pre- and postcompensation. The effective launch power of the WDM channel is increased more in the optical links with NRD = +10 ps/nm controlled by only precompensation. Furthermore, the system performance difference between the proposed optical link configuration with the best NRD and the conventional optical link with uniform distribution of the SMF length had little significance. Consequently, it is confirmed that the proposed optical link configuration with the best NRD is effective and useful for implementing a reconfigurable long-haul WDM network.

Sliding Wear Characteristics of plasma Sprayed $8\%Y_{2}O_3-ZrO_2$ Coating for Post-spray Heat Treatment

  • Chae Young-Hun;Kim Seock-Sam
    • KSTLE International Journal
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    • v.6 no.2
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    • pp.45-50
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    • 2005
  • Plasma ceramic spray that is applied on a machine part under severe work conditions has been investigated for tribological behavior. The application of ceramic coatings by plasma spray has become essential in tribosystems to produce wear resistance and long life in severe conditions. The purpose of this study was to investigate the wear characteristics of $8\%Y_{2}O_3-ZrO_2$ coating, in view of the effect of post-spay heat treatment. The plasma-sprayed $8\%Y_{2}O_3-ZrO_2$ coating was studied to know the relationship between phase transformations and wear behavior related to post-spray heat treatment. Wear test was carried out with ball on disk type on normal loads of 50N,70N and 90N under room temperature. The phase transformation of phase and the value of residual stress were measured by X-ray diffraction method(XRD). Tribological characteristics and wear mechanisms of coatings were observed by SEM. The tribological wear performance was discussed in the focusing of residual stress. Consequently, post-spray heat treatment plays an important role in decreasing residual stress. Residual stress in the coating system has a significant influence on the wear mechanism of coating.

Effect of cooling rate on the post-fire behavior of CFST column

  • Afaghi-Darabi, Alireza;Abdollahzadeh, Gholamreza
    • Computers and Concrete
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    • v.23 no.4
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    • pp.281-294
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    • 2019
  • The post-fire behavior of structural elements and the cooling process has always been one of the main concerns of the structural engineers. The structures can be cooled at different rates, where they affect the structure's behavior. In the present study, a numerical model has been developed using the Abaqus program to investigate the effect of cooling rate on the post-fire behavior of the CFST column. To verify the model, results of an experimental study performed on CFST columns within a full heating and cooling cycle have been used. In this model, coMParison of the residual strength has been employed in order to examine the behavior of CFST column under different cooling rates. Furthermore, a parametric study was carried out on the strength of steel and concrete, the height of the specimens, the axial load ratio and the cross-sectional shape of the specimen through the proposed model. It was observed that the cooling rate affects the behavior of the column after the fire, and thus the higher the specimen's temperature is, the more effect it has on the behavior. It was also noticed that water cooling had slightly more residual strength than natural cooling. Furthermore, it was recognized from the parametric study, that by increasing the strength of steel and concrete and the load ratio, as well as modifying the cross-sectional shape from circular to square, residual strength of column at the cooling phase was less than that of the heating phase. In addition, with reducing column height, no change was witnessed in the column behavior after the cooling phase.

A new dual-mode blind equalization algorithm combining carrier phase recovery (반송파 위상 복원을 결합한 새로운 이중모드 블라인드 등화 알고리즘)

  • 오길남;진용옥
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.32A no.5
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    • pp.14-23
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    • 1995
  • A new dual-mode algorithm for blind equalization of quadrature amplitude modulation (QAM) signals is proposed. To solve the problem that the constant modulus algorithm (CMA) converges to the constellation with the arbitrary phase rotation, with the modification of the CMA, the proposed algorithm accomplishes blind equalization and carrier phase recovery simultaneously. In addition, the dual-mode algorithm combining the modified constant modulus algorithm (MCMA) with decision-directed (DD) algorithm achieves the performance enhancement of blind convergence speed and steady-state residual ISI. So we can refer the proposed algorithm to as a scheme for joint blind equalization and carrier phase recovery. Simulation results for i.i.d. input signals confirm that the dual-mode algorithm results in faster convergence speed, samller residual ISI, and better carrier phase recovery than those of the CMA and DD algorithm without any significant increase in computational complexity.

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Performance Improvement of WDM Signals through Precompensation and Postcompensation in Dispersion Managed Optical Transmission Links with Artificial Distribution of Single Mode Fiber Length and RDPS (인위적인 단일 모드 광섬유 길이와 RDPS 분포를 갖는 분산 제어 광전송 링크에서 선치 보상과 후치 보상을 통한 WDM 신호의 성능 개선)

  • Lee, Seong-Real
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.16 no.10
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    • pp.2293-2302
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    • 2012
  • New optical transmission links technique for compensating of the distorted wavelength division multiplexed (WDM) signals due to group velocity dispersion (GVD) and self phase modulation (SPM) in single mode fiber (SMF) are proposed. The proposed optical links have optical phase conjugator (OPC) placed at nearby WDM transmitter or receiver and repeater spans with artificial distribution of SMF length and residual dispersion per span (RDPS). It is confirmed that optimal link configuration expanding effective launching power range and effective net residual dispersion (NRD) by improving system performance is that having OPC closely placed at WDM receiver and the gradually descended distribution of SMF length and RDPS of each repeater spans, related with the gradually increased optical link length. And, it is also confirmed that NRD is controlled by postcompensation in optimal optical link with OPC closely placed at WDM receiver.

Induction of Optimal Condition of 40 Gbps RZ Format for OTDM/WDM Transmission (OTDM/WDM 전송을 위한 40 Gbps RZ 형식의 최적 조건 도출)

  • Lee, Seong-Real
    • Journal of Advanced Navigation Technology
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    • v.14 no.6
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    • pp.831-837
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    • 2010
  • Optimal conditions of 40 Gbps RZ format for implementation of optical time division multiplexing/wavelength division multiplexing (OTDM/WDM) transmission system are induced by analyzing and comparing performance depending on duty cycle and extinction ratio (ER). Optical phase conjugator (OPC) and inline dispersion management (DM) are applied into optical transmission links for compensating signal distortion due to chromatic dispersion and nonlinearity of fiber. It is confirmed that RZ format of 0.25 duty cycle is less effected by system performance change depending on ER and it is suitable for multiplexing to 160 Gbps signal through OTDM. Also, it is shown that performance improvement of RZ format determined by same net residual dispersion (NRD) is more increased as residual dispersion per span (RDPS) becomes large.

A DS/CDMA Code Acquisition Scheme to Reduce the System Performance Variation Resulting from Residual Code Phase Offset (나머지 부호 위상차가 일으키는 시스템 성능변화를 줄이는 직접수열 부호분할 다중접속 부호 획득 방법)

  • Yun, Seok-Ho;Yun, Hyeong-Sik;Song, Ik-Ho;Kim, Seon-Yong;Lee, Yong-Eop
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.37 no.4
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    • pp.25-34
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    • 2000
  • In this paper, we first investigate the effect of residual code phase offset on the DS/CDMA code acquisition scheme. When the code phase offset normalized to the chip duration is within the advancing step size, the sum of two successive matched filter outputs has a constant value regardless of the residual code phase offset if noise is absent. Based on this observation, we propose a new code acquisition scheme, and investigate the performance of the scheme. The Proposed code acquisition scheme is analyzed, and numerical results are given to show that the proposed scheme is more robust to the variation of the residual code phase offset and has better performance than the conventional scheme.

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Chemical Speciation and Potential Mobility of Heavy Metals in Tailings and Contaminated Soils (광미 및 오염된 토양에서 중금속의 존재형태 및 잠재적인 이동도)

  • 이평구;강민주;최상훈;신성천
    • Economic and Environmental Geology
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    • v.37 no.1
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    • pp.87-98
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    • 2004
  • Tailings and contaminated soils from Cheongyang mine and Seobo mine have been analysed by ICP-AES from 5-step sequential extraction method of multielement determination on extraction solutions at each step. As and Co within tailings and contaminated soils from Cheongyang mine and Seobo mine are mainly in the residual phase. In case of Cd, Cu and Zn, the most dominant fraction for tailings of Cheongyang mine is the oxidizable phase, while tailings of Seobo mine is dominated by the residual phase. In contaminated soils from Seobo mine, the predominant fraction for Cd, Cu and Zn is the Fe-Mn oxide phase. The exchangeable fraction of Pb in tailings from Cheongyang mine and Seobo mine is relatively high compared with those of other metals; whereas Pb fraction in contaminated soils from Seobo mine is largely associated with the residual fraction.

Sensorless Control of a Single-Phase Switched Reluctance Motor Using Residual Flux

  • Yang, Hyong-Yeol;Shin, Duck-Shick;Lim, Young-Cheol
    • Journal of Power Electronics
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    • v.9 no.6
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    • pp.911-918
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    • 2009
  • This paper presents a new sensorless control method for single-phase switched reluctance motors using induced electromotive force (EMF) due to the residual flux both on the stator and the rotor during phase commutation. The induced EMF falls to zero when the rotor pole moves away from the overlap with the stator pole. By detecting this instant, the speed and position of the rotor can be simply estimated. This method is very simple to implement and it is insensitive to variations in the system parameters as it does not require any stored magnetic data or offline inductance measurements but requires only measurements of the terminal voltage and a simple analog circuit. The proposed method is implemented on a 6/6 single-phase switched reluctance motor. However, it can also be implemented on a multiphase SRM regardless of the size, operation speed and switching mode of the motor hence making the proposed method viable to many applications. Simulation and experimental verification is provided to demonstrate the feasibility of the proposed method.

Locating the Change Point of Mean Residual Life of Certain Life Distributions

  • Li, Xiaohu
    • International Journal of Reliability and Applications
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    • v.3 no.2
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    • pp.91-98
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    • 2002
  • A class of life distributions, whose mean residual life keeps stable at its earlier phase and then starts to decrease in time, is proposed to model the life of an element haying survived its burn-in. A strongly consistent estimator and a nonparametric testing procedure are developed to locate the occurrence of the change-point of the mean residual life. Finally, some numerical simulations are employed to be an illustration as well.

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