• Title/Summary/Keyword: residual phase

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Improvement of Residual Delay Compensation Algorithm of KJJVC (한일상관기의 잔차 지연 보정 알고리즘의 개선)

  • Oh, Se-Jin;Yeom, Jae-Hwan;Roh, Duk-Gyoo;Oh, Chung-Sik;Jung, Jin-Seung;Chung, Dong-Kyu;Oyama, Tomoaki;Kawaguchi, Noriyuki;Kobayashi, Hideyuki;Kawakami, Kazuyuki;Ozeki, Kensuke;Onuki, Hirohumi
    • Journal of the Institute of Convergence Signal Processing
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    • v.14 no.2
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    • pp.136-146
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    • 2013
  • In this paper, the residual delay compensation algorithm is proposed for FX-type KJJVC. In case of initial version as that design algorithm of KJJVC, the integer calculation and the cos/sin table for the phase compensation coefficient were introduced in order to speed up of calculation. The mismatch between data timing and residual delay phase and also between bit-jump and residual delay phase were found and fixed. In final design of KJJVC residual delay compensation algorithm, the initialization problem on the rotation memory of residual delay compensation was found when the residual delay compensated value was applied to FFT-segment, and this problem is also fixed by modifying the FPGA code. Using the proposed residual delay compensation algorithm, the band shape of cross power spectrum becomes flat, which means there is no significant loss over the whole bandwidth. To verify the effectiveness of proposed residual delay compensation algorithm, we conducted the correlation experiments for real observation data using the simulator and KJJVC. We confirmed that the designed residual delay compensation algorithm is well applied in KJJVC, and the signal to noise ratio increases by about 8%.

Improvement of Photo-Alignment Characteristics for Device Applications

  • Hwang, Yong-Jae;Choi, Kil-Yeong;Yi, Mi-Hie;Hong, Sung-Hwan;Shin, Dong-Myung
    • 한국정보디스플레이학회:학술대회논문집
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    • 2007.08a
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    • pp.867-870
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    • 2007
  • In order to solve image sticking phenomena, the gas-phase and liquid-phase interfacial reactions of photosensitive polyimide can annihilate photoreactive carbon-carbon double bonds, which remain after photo-alignment process. The annihilation processes dramatically affect residual DC and photochemical reorientation of photoactive functional groups.

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Effect of an temperatures of post-spray heat treatment on wear behavior of $8%Y_2O_3-ZrO_2$ coating

  • Chae, Y.H.;Kim, S.S.
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2002.10b
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    • pp.181-182
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    • 2002
  • Most recent, Plasma ceramic spray is used on parts of tribosystem, has been investigated on the tribological performance. The application of ceramic coatings by plasma spray has become essential in tribosystems to produce better wear resistance and longer life in various conditions. The purpose of this work was to investigate the wear behavior of $8%Y_2O_3-ZrO_2$ coating due to temperatures of post-spay heat treatment. The plasma-sprayed $8%Y_2O_3--Zirconia$ coating was idiscussed to know the relationship between phase transformations and temperatures of post- spray heat treatment. Wear tests was carried out with ball on disk type on normal load of 50N, 70N and 90N under room temperature. The transformation of phase and the value of residual stress were measured by X-ray diffraction method(XRD). Tribological characteristics and wear mechanisms of coatings was observed by SEM. The tribologieal wear performance was discussed a point of view for residual stress. Consequently. post-spray heat treatment plays an important role in decreasing residual stress. Residual stress in coating system has a significant influence on the wear mechanism of coating.

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A Study on Zirconia/Metal Functionally Gradient Materials by Sintering Method (III) (소결법에 의한 $ZrO_2/Metal$계 경사기능재료에 관한 연구(III))

  • 정연길;최성철;박철원
    • Journal of the Korean Ceramic Society
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    • v.32 no.12
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    • pp.1337-1348
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    • 1995
  • TZP/SUS- and ZT/SUS-functionally gradient materials (FGM) were fabricated by pressureless sintering in Ar-atmosphere. The sintering defects such as warping, frustrum formation, splitting and cracking which originated from shrinkage and sintering behaviors of metal and ceramics different from each other could be controlled by the adjustment with respect to the particle size and phase type of zirconia. The residual stresses generated on the metal and ceramic regions in FGM were characterized with X-ray diffraction method, and relaxed as the thickness and number of compositional gradient layer were increased. The residual stress states in TZP/SUS-FGM have irregular patterns by means of the different sintering behavior and cracking at ceramic-monolith. While in ZT/SUS-FGM, compressive stress is induced on ceramic-monolith by the volume expansion of monoclinic ZrO2 at phase transformation. Also, compressive stress is induced on metal-monolith by the constraint of warping which may be created to the metal direction by the difference of coefficient of thermal expansions. As a consequence, it has been verified that the residual stress generated on FGM is dominantly influenced by the thickness and number of compositional gradient layer, and the sintering defects and residual stress can be controlled by the constraint of the difference of shrinkage and sintering behaviors of each component.

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Wear characteristics of plasma sprayed yttria-stabilized zirconia coating as phase transformation (지르코니아 용사코팅의 상변화에 따른 마멸특성)

  • Park, Chan;Chae, Young-Hun;Kim, Seock-Sam
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2001.11a
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    • pp.322-330
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    • 2001
  • The plasma-sprayed 8%Y$_2$O$_3$-Zirconia coating was studied to know the relationship between phase transformation and wear properties after several heat treatment. Wear tests were carried out with ball on disk on 50N, 70N, 90N. The specimen in this study was cast iron and tests were performed on room temperature. The transformation of phase and residual stress was measured by x-ray diffraction method(XRD) and worn surface were observed by SEM.

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Dispersion-managed Transmission Links with the Non-midway Optical Phase Conjugator (Non-midway 광 위상 공액기를 갖는 분산 제어 링크)

  • Lee, Seong-Real
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2017.05a
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    • pp.744-746
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    • 2017
  • The maximum number of fiber spans is induced in disoersion-managed optical links with the non-midway optical phase conjugator (OPC) for the compensation of the distorted WDM signals due to the group velocity dispersion (GVD) are evaluated and compared.

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Dispersion-managed Transmission Links with the Non-midway Optical Phase Conjugator (Non-midway 광 위상 공액기를 갖는 분산 제어 링크)

  • Lee, Seong-Real
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2017.10a
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    • pp.671-673
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    • 2017
  • The maximum number of fiber spans is induced in disoersion-managed optical links with the non-midway optical phase conjugator (OPC) for the compensation of the distorted WDM signals due to the group velocity dispersion (GVD) are evaluated and compared.

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A Development of ZnO Varistor for Railroad Vehicle d.c. Arrester (전철탑재형 직류피뢰기용 ZnO 바리스터의 개발)

  • Cho, I-Gon;Park, Choon-Hyun;Jung, Se-Young;Song, Tae-Kwon;Kim, Suk-Soo
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2002.11a
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    • pp.552-556
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    • 2002
  • The microstructure and electrical characteristics of A~C's ZnO varistors fabricated according to variable sintering condition, which sintering temperature is $1130^{\circ}C$ and speeds of pusher are A: 2mm/min, B: 4mm/min, C: 6mm/min, respectively, were investigated. In the microstructure, A~C's ZnO varist-ors fabricated variable sintering condition was consisted of ZnO grain(ZnO), spinel phase$(Zn_{2.33}Sb_{0.67}O_4)$ Bi-rich $phase(Bi_{2}O_{3})$, wholly. Varistor voltage of A~C's ZnO varistors sintered at $1130^{\circ}C$ increased in order A < B < C's ZnO varistors. C's ZnO varistor exhibited good characteristics that nonlinear exponent is 31.70. Leakage current of A~C's ZnO varistors exhibited below 2mA at rated voltage. Lightning impulse residual voltage of A's ZnO varistor suited standard characteristics, which is 3.85kV at 2.5kA, 4.4kV at 5kA and 5.16kV at 10kA. After multi lightning impulse residual voltage test of A's ZnO varistor exhibited good discharge characteristics which ZnO varistor reveals no evidence of puncture, flashover, cracking in visual examination. After high current impulse test of A's ZnO varistor exhibited good discharge characteristics, which variation rate of residual voltage is 0.4% before and after test, and revealed no evidence.

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Effect of stress relief heat treatment on the residual stress and hardness of additively manufactured Ti-6Al-4V alloy (응력제거 열처리 공정조건이 적층제조한 Ti-6Al-4V 합금의 잔류응력 및 경도에 미치는 영향)

  • Yeonghwan Song
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.33 no.6
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    • pp.282-287
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    • 2023
  • The effect of stress relief heat treatment temperature and duration time on the microstructure, residual stress and Vickers hardness of additively manufactured Ti-6Al-4V alloy using laser powder bed fusion process was clarified. As a result of stress relief heat treatment for 240 minutes at 823 K and 60 minutes or more at 873 K, residual stress was decreased less than 30 MPa without grain growth and phase transformation which causes dimensional distortion and deterioration of mechanical properties. In addition, hardness was increased with increasing heat treatment temperature and duration time. It was deduced that the refinement of acicular martensitic α' phase due to the increasing duration time of isothermal heat treatment at 773~873 K, which was not detected by XRD and phase map analysis using SEM-EBSD, probably increases the hardness.

Pseudo-symmetrically Dispersion-Managed Optical Transmission Links with Midway OPC for Compensating for Distorted WDM Signals

  • Lee, Seong-Real
    • Journal of information and communication convergence engineering
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    • v.13 no.4
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    • pp.228-234
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    • 2015
  • The system performance improvement in dispersion managed (DM) links combined with optical phase conjugator (OPC) for compensating for optical signal distortion due to group velocity dispersion and nonlinear fiber effects has been reported. However, in DM link combined OPC, the equalities of the lengths of single-mode fibers (SMFs), the length of dispersion compensating fibers (DCFs), the dispersion coefficient of DCF, and the residual dispersion per span (RDPS) with respect to an OPC restrict a flexible link configuration. Thus, in this paper, we propose a flexible optical link configuration with inequalities of link parameters, the so-called "pseudo-symmetric configuration." Simulation results show that, in the restricted RDPS range of 450 ps/nm to 800 ps/nm, the improvement in the system performance of the proposed pseudo-symmetrically configured optical links is better than that of the asymmetrically configured optical links. Consequently, we confirmed that the proposed pseudo-symmetric configuration is effective and useful for implementing a reconfigurable long-haul wavelength-division multiplexing (WDM) network.