• Title/Summary/Keyword: Longitudinal Strain

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Preliminary investigation of Ic homogeneity along the longitudinal direction of YBCO coated conductor tape under tensile loading

  • Dizon, J.R.C.;Oh, S.S.;Sim, K.D.;Shin, H.S.
    • Progress in Superconductivity and Cryogenics
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    • v.15 no.2
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    • pp.24-28
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    • 2013
  • In this study, the homogeneity of critical current, $I_c$, along the lengthwise direction in the coated conductor (CC) tape under uniaxial tension was investigated using a multiple voltage tap configuration. Initially, a gradual and homogeneous $I_c$ degradation occurred in all subsections of the tape up to a certain strain value. This was followed by an abrupt $I_c$ degradation in some subsections, which caused scattering in $I_c$ values along the length with increasing tension strain. The $I_c$ degradation behaviour was also explained through n-value as well as microstructure analyses. Subsections showed $I_c$ scattering corresponding to damaged areas of the CC tape revealed that transverse cracks were distributed throughout the gauge length. This homogeneous $I_c$ degradation behaviour under tension is similar with the case under torsion strain but different with the case under hard bending which were previously reported. This behaviour is also different with the case using Bi-2223 HTS tapes under tension strain.

Welding Deformation Analysis of Plates Using the Inherent Strain-based Equivalent Load Method (고유변형률 기반 등가하중법을 이용한 판의 용접변형 해석)

  • Lee, Joo-Sung
    • Journal of Welding and Joining
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    • v.28 no.2
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    • pp.39-46
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    • 2010
  • IIn this study, used is the equivalent loading method based on the inherent strain to predict the welding deformation of panel members. Equivalent loads are computed from the inherent strain distribution around weld line, and then applied for the linear finite element analysis. Thermal deformation of panel members can be, of course, carried out through the rigorous thermal elasto-plastic analysis procedure but it is not practical in applying to predicting the welding deformation of large structures such as blocks found in a ship structure from view of computing time. The present equivalent load approach has been applied to flat plate model to verify the present approach, and to several curved plate models having the curvature in the welding direction to investigate the effect of the longitudinal curvature upon the weld-induced deformation. The results are compared with those by thermal elasto-plastic analysis. As far as the present results are concerned, it can be said that the present approach shows good agreement with the results by welding experiment and the rigorous thermal elasto-plastic analysis. The present approach has been also applied to predict the welding deformation of panel block as for application illustration to practical model.

Ceramic Pressure Sensors Based on CrN Thin-films (CrN박막 세라믹 압력센서)

  • Chung, Gwiy-Sang;Seo, Jeong-Hwan;Ryu, Gl-kyu
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2000.07a
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    • pp.573-576
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    • 2000
  • The physical, electrical and piezoresitive characteristics of CrN(chromium nitride) thin-films on silicon substrates have been investigated for use as strain gauges. The thin-film depositions have been carried out by DC reactive magnetron sputtering in an argon-nitrogen atmosphere(Ar-(5∼25 %)Na$_2$). The deposited CrN thin-films with thickness of 3577${\AA}$ and annealing conditions(300$^{\circ}C$, 48 hr) in Ar-10 % N$_2$deposition atmosphere have been selected as the ideal piezoresistive material for the strain gauges. Under optimum conditions, the CrN thin-films for the strain gauges is obtained a high electrical resistivity, $\rho$=1147.65 ${\mu}$$\Omega$cm, a low temperature coefficient of resistance, TCR=-186 ppm/$^{\circ}C$ and a high temporal stability with a good longitudinal gauge factor, GF=11.17.

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Nonlocal strain gradient theory for bending analysis of 2D functionally graded nanobeams

  • Aicha Bessaim;Mohammed Sid Ahmed Houari;Smain Bezzina;Ali Merdji;Ahmed Amine Daikh;Mohamed-Ouejdi Belarbi;Abdelouahed Tounsi
    • Structural Engineering and Mechanics
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    • v.86 no.6
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    • pp.731-738
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    • 2023
  • This article presents an analytical approach to explore the bending behaviour of of two-dimensional (2D) functionally graded (FG) nanobeams based on a two-variable higher-order shear deformation theory and nonlocal strain gradient theory. The kinematic relations are proposed according to novel trigonometric functions. The material gradation and material properties are varied along the longitudinal and the transversal directions. The equilibrium equations are obtained by using the virtual work principle and solved by applying Navier's technique. A comparative evaluation of results against predictions from literature demonstrates the accuracy of the proposed analytical model. Moreover, a detailed parametric analysis checks for the sensitivity of the bending and stresses response of (2D) FG nanobeams to nonlocal length scale, strain gradient microstructure scale, material distribution and geometry.

Subclinical left ventricular dysfunction in children after hematopoietic stem cell transplantation for severe aplastic anemia: a case control study using speckle tracking echocardiography

  • Kim, Beom Joon;Moon, Kyung Pil;Yoon, Ji-Hong;Lee, Eun-Jung;Lee, Jae Young;Kim, Seong Koo;Lee, Jae Wook;Chung, Nack Gyun;Cho, Bin;Kim, Hack Ki
    • Clinical and Experimental Pediatrics
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    • v.59 no.4
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    • pp.190-195
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    • 2016
  • Purpose: Severe aplastic anemia (SAA), a fatal disease, requires multiple transfusion, immunosuppressive therapy, and finally, hematopoietic stem cell transplantation (HSCT) as the definitive treatment. We hypothesized that iron overloading associated with multiple transfusions and HSCT-related complications may adversely affect cardiac function. Left ventricular (LV) function was assessed in children after HSCT for SAA. Methods: Forty-six consecutive patients with a median age of 9.8 years (range, 1.5-18 years), who received HSCT for SAA and who underwent comprehensive echocardiography before and after HSCT, were included in this study. The data of LV functional parameters obtained using conventional echocardiography, tissue Doppler imaging (TDI), and speckle-tracking echocardiography (STE) were collected from pre- and post-HSCT echocardiography. These data were compared to those of 40 age-matched normal controls. Results: In patients, the LV ejection fraction, shortening fraction, end-diastolic dimension, mitral early diastolic E velocity, TDI mitral septal E' velocity, and STE LV longitudinal systolic strain rate (SSR) decreased significantly after HSCT. Compared to normal controls, patients had significantly lower post-HSCT early diastolic E velocity and E/A ratio. On STE, patients had significantly decreased LV deformational parameters including LV longitudinal systolic strain (SS), SSR, and diastolic SR (DSR), and circumferential SS and DSR. Serum ferritin levels showed weak but significant correlations (P<0.05) with LV longitudinal SS and SSR and circumferential SS and DSR. Conclusion: Subclinical LV dysfunction is evident in patients after HSCT for SAA, and was associated with increased iron load. Serial monitoring of cardiac function is mandatory in this population.

Influence of Transverse Reinforcement Elements for Flexural Strength of Lap Spliced Ultra-high-strength Reinforced Concrete Beams (겹침이음된 초고강도콘크리트 보의 휨강도에 횡방향보강 요소가 미치는 영향)

  • Bae, Baek-Il;Choi, Hyun-Ki
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.26 no.5
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    • pp.135-142
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    • 2022
  • In this study, lap spliced ultra-high strength reinforced concrete beams were tested and the code criteria for calculating the lap splice length which was affected by the transverse reinforcement and concrete covering performance were reviewed. The main variables for test were set as fiber volume fraction and transverse reinforcing bar arrangement to improve the confining performance of the concrete cover. The change of the confining performance of concrete cover according to the increase in the fiber mixing amount at 1% and 2% volume ratio was examined, and D10 stirrups with a spacing of 100 mm were placed in the lap spliced region. As a result of the test, the specimens confined by the stirrups showed a sudden drop of load bearing capacity with horizontal cracking at the position of tensile longitudinal reinforcement. However, horizontal cracks were not appeared at the location of longitudinal reinforcement for the specimens with steel fiber. And these specimens showed gradual decrease of load bearing capacity after experiencing peak load. In particular, it was found that the strain at the position of the tensile longitudinal reinforcements of the specimens to which the mixing ratio of 2% was applied exceeds the yield strain. As a result of measuring the strain on the concrete surface, it was found that the fiber was more effective in preventing damage to the concrete surface than the stirrups for short lap spliced region.

Comparison of Cytoplasmic Inclusions Induced by Maize Dwarf Mosaic Virus Strain A and B (Maize Dwarf Mosaic Virus strain A와 B에 의해 유도된 세포질 봉입체의 비교분석)

  • Choi, Chang-Won;Gardner, Wayne S.
    • Applied Microscopy
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    • v.24 no.2
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    • pp.105-114
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    • 1994
  • Comparative ultrastructural studies of sorghum (Sorghum bicolor L. Moench) cultivar (cv.) HOK and cv Pioneer 8680 leaf cells separately infected with maize dwarf mosaic virus (MDMV) strain A and B, respectively, revealed the formation of numerous cylindrical inclusions in both cross and longitudinal sections. The MDMV-A and -B were distinguished by the presence or absence of specific inclusion bodies in the cytoplasm. Electron microscope revealed the presence of pinwheels, bundles, scrolls, and laminated aggregates in Pioneer 8680 sorghum leaf cells infected with MDMV-B while no laminated aggregates were found in cells of HOK sorghum leaf cells infected with MDMV-A. Differences in the ultrastructure of cylindrical inclusions between two strains of MDMV, especially with respect to laminated aggregates, have been morphologically indexed to classify potyviruses into subdivision. The presence of laminated aggregates may be assigned to subdivision III while the absence of laminated aggregates is assigned to subdivision I. These variations of structures associated with cylindrical inclusions appeared virus-specific inductions and may be represented the morphogenesis of inclusion bodies following development of infections.

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Right Ventricular Strain Is Associated With Increased Length of Stay After Tetralogy of Fallot Repair

  • Ranjini Srinivasan;Jennifer A. Faerber;Grace DeCost;Xuemei Zhang;Michael DiLorenzo;Elizabeth Goldmuntz;Mark Fogel;Laura Mercer-Rosa
    • Journal of Cardiovascular Imaging
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    • v.30 no.1
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    • pp.50-58
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    • 2022
  • BACKGROUND: Little is known regarding right ventricular (RV) remodeling immediately after Tetralogy of Fallot (TOF) repair. We sought to describe myocardial deformation by cardiac magnetic resonance imaging (CMR) after TOF repair and investigate associations between these parameters and early post-operative outcomes. METHODS: Fifteen infants underwent CMR without sedation as part of a prospective pilot study after undergoing complete TOF repair, prior to hospital discharge. RV deformation (strain) was measured using tissue tracking, in addition to RV ejection fraction (EF), volumes, and pulmonary regurgitant fraction. Pearson correlation coefficients were used to determine associations between both strain and CMR measures/clinical outcomes. RESULTS: Most patients were male (11/15, 73%), with median age at TOF repair 53 days (interquartile range, 13,131). Most patients had pulmonary stenosis (vs. atresia) (11/15, 73%) and 7 (47%) received a transannular patch as part of their repair. RV function was overall preserved with mean RV EF of 62% (standard deviation [SD], 9.8). Peak radial and longitudinal strain were overall diminished (mean ± SD, 33.80 ± 18.30% and -15.50 ± 6.40%, respectively). Longer hospital length of stay after TOF repair was associated with worse RV peak radial ventricular strain (correlation coefficient (r), -0.54; p = 0.04). Greater pulmonary regurgitant fraction was associated with shorter time to peak radial RV strain (r = -0.55, p = 0.03). CONCLUSIONS: In this small study, our findings suggest presence of early decrease in RV strain after TOF repair and its association with hospital stay when changes in EF and RV size are not yet apparent.

An Evaluation of Stress-Strain Behaviour of Earth-Rockfill Dam and Causes of Crack due to Water Table Fluctuation (수위변동에 따른 Earth-Rockfill 댐의 거동 및 균열원인에 대한 평가)

  • 김상규;한성길;이민형;안상로
    • Journal of the Korean Geotechnical Society
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    • v.17 no.6
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    • pp.149-162
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    • 2001
  • Longitudinal cracks have occurred on the crest of dams soon after their construction of two earth-rocfill dams located in Samlangjin. They are a pair of pumped storage dams constructed for generation of electrical power. The upper dam and lower dam are subjected to the variation of water level more than 10m once in a day alteratively. This paper deals with the finding of possible causes for longitudinal cracks about upper dam. The dominant cause was considered to be due to fluctuation of water load, for which numerical analysis was carried out using the hyperbolic model. In order to obtain parameters necessary to the analysis, a series of triaxial tests was performed for both core and rock material. Also dynamic triaxial test was performed to obtain dynamic properties of soils, which could be used as input data to simulate frequent variation of stress change due to the water fluctuation. It was known from the numerical analysis that the confining pressure of upper 4m from the top of the crest become negative after repeating of water load, meaning that tension cracks occurred in the top portion of the crest. The depth of longitudinal cracks has been investigated by digging test pit on the crest. This results agree with the field observation.

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Displacement Ductility Ratio of Reinforced Concrete Bridge Piers with Lap-splices (주철근 겹침이음 비율에 따른 RC교각의 연성능력 평가)

  • Park, Kwang-Soon;Ju, Hyeong-Seok;Shin, Hyun-Mock;Kim, Moon-Kyum
    • Journal of the Earthquake Engineering Society of Korea
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    • v.12 no.6
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    • pp.1-12
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    • 2008
  • As internal and external seismic experiment results, the seismic performance of RC bridge piers is largely dependent on the ratio of lap-spliced bars to all longitudinal reinforcing bars in plastic hinge regions, and confining effects of transverse reinforcements. Capacity and displacement ductility of non-seismically designed existing RC piers are reduced by lap splices in plastic hinge regions. The provision for the lap splice of longitudinal reinforcing bars was not specified in KBDS (Korean Bridge Design Specifications) before the implementation of 1992 seismic design code, but the ratio of lap-spliced bars to all longitudinal reinforcing bars in plastic hinge regions is restricted to 50% in the 2005 version of KBDS. This paper presents a seismic assessment of RC piers at lap-splicing ratios of 0%, 50%, and 100%. Through a comparison of experimental and analytic results of RC piers, we introduce an appropriate ultimate strain of confined concrete in plastic hinge regions with lap-splices, and propose a method for estimating displacement ductility ratios of non-seismically designed existing RC piers using fiber element analysis.