• Title/Summary/Keyword: Damage Tolerance

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Low velocity impact characteristics on environmental variation of composite laminates used in the light rail transit (경량전철 복합 적층판의 환경변화에 대한 저속충격특성)

  • 김후식;김재훈;이영신;박병준;조정미
    • Proceedings of the KSR Conference
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    • 2002.10a
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    • pp.86-91
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    • 2002
  • Glass/phenolic composite laminates have been used in the field of non-flammable light rail transit and their applications have expanded more widely. Low velocity impact tests have been used to evalute the effect of temperature and acceleration aging on low velocity impact response of phenolic matrix composites reinforced with woven E-glass fabric. The damage of matrix cracking and delamination are suddenly reduced the compressive strength after impact. The damage area increases with increasing temperature and impact energy. UT C-scan is used to determine damage areas by impact loading. Therefore, all this observations indicate reduced impact damage resistance and damage tolerance of the laminates at elevated temperature.

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Study on the Salt Tolerance of Rice and Other Crops in Reclaimed 2. On the Salt Tolerance of Chinese Cabbage and Cabbage in Various Salty Conditions (간척지에서 수도 및 기타작물의 내염성에 관한 연구 2. 여러 가지 염분조건에서 배추와 양배추의 내염성에 관하여)

  • 임형빈
    • Journal of Plant Biology
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    • v.12 no.3
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    • pp.8-14
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    • 1969
  • Salt tolerances of Chinese cabbage and cabbage were observed by means of the sand culture and field experiment. The point of 50% yield reduction of Chinese Cabbage was 1% of salt concentration in sand culture. The Na absorption in the salty upland conditions was increased but the absorption of Ca, Mg were interrupted as the salt concentration was raised and there were no differences in the absorption of N and P. The Si absorption was increased at low salty conditions, but the salt concentration was raised, the absorption was interrupted drastically. The cabbage was more stronger salt tolerance than Chinese cabbage, and it was possible to prevent the salt damage significantly by planting on sloping beds instead of planting on the double-row beds in field condition.

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Structural damage alarming and localization of cable-supported bridges using multi-novelty indices: a feasibility study

  • Ni, Yi-Qing;Wang, Junfang;Chan, Tommy H.T.
    • Structural Engineering and Mechanics
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    • v.54 no.2
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    • pp.337-362
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    • 2015
  • This paper presents a feasibility study on structural damage alarming and localization of long-span cable-supported bridges using multi-novelty indices formulated by monitoring-derived modal parameters. The proposed method which requires neither structural model nor damage model is applicable to structures of arbitrary complexity. With the intention to enhance the tolerance to measurement noise/uncertainty and the sensitivity to structural damage, an improved novelty index is formulated in terms of auto-associative neural networks (ANNs) where the output vector is designated to differ from the input vector while the training of the ANNs needs only the measured modal properties of the intact structure under in-service conditions. After validating the enhanced capability of the improved novelty index for structural damage alarming over the commonly configured novelty index, the performance of the improved novelty index for damage occurrence detection of large-scale bridges is examined through numerical simulation studies of the suspension Tsing Ma Bridge (TMB) and the cable-stayed Ting Kau Bridge (TKB) incurred with different types of structural damage. Then the improved novelty index is extended to formulate multi-novelty indices in terms of the measured modal frequencies and incomplete modeshape components for damage region identification. The capability of the formulated multi-novelty indices for damage region identification is also examined through numerical simulations of the TMB and TKB.

A Study on the Damage Design of Military Aircraft Structure Material by Armor Piercing Bullet Hit (철갑탄 피격에 의한 군용 항공기 구조재료의 손상설계에 관한 연구)

  • Hur, Jang-Wook;Hyun, Young-Jin
    • Journal of the Korea Institute of Military Science and Technology
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    • v.13 no.6
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    • pp.1051-1057
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    • 2010
  • Database for the damage reference by armor piercing bullet test was established for both tube and plate specimens having a range of thickness. As the inclined angles of hit are increasing, it has been found that penetration damage diameter tends to increases accordingly in both specimen of the tube and plate, and such penetration damage diameter on the rear side becomes bigger than those on the front side. The tube specimen showed that the damage becomes bigger when central areas rather than the peripheral were hit. Through the plate test, it also has been found that the penetration ballistic limit for Al alloy is about 25.4mm and that of stainless steel about 12.7mm. From the fatigue analysis results using the database for damage reference, it has been identified whether the safety requirements of military aircraft could be met.

Improvement of Drought Tolerance in Transgenic Tobacco Plant (형질전환 담배의 내건성 개선)

  • Park, Yong Mok
    • Journal of Environmental Science International
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    • v.25 no.1
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    • pp.173-179
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    • 2016
  • Leaf water and osmotic potential, chlorophyll content, photosynthetic rate, and electrolyte leakage were measured to evaluate tolerance to water stress in wild-type (WT) and transgenic tobacco plants (TR) expressing copper/zink superoxide dismutase (CuZnSOD) and ascorbate peroxidase (APX) in chloroplasts. Leaf water potential of both WT and TR plants decreased similarly under water stress condition. However, leaf osmotic potential of TR plants more negatively decreased in the process of dehydration, compared with WT plants, suggesting osmotic adjustment. Stomatal conductance (Gs) in WT plants markedly decreased from the Day 4 after withholding water, while that in TR plants retained relatively high values. Relatively low chlorophyll content and photosynthetic rate under water stress were shown in WT plants since $4^{th}$ day after treatment. In particular, damage indicated by electrolyte leakage during water stress was higher in WT plants than in TR plants. On the other hand, SOD and APX activity was remarkably higher in TR plants. These results indicate that transgenic tobacco plants expressing copper/zink superoxide dismutase (CuZnSOD) and ascorbate peroxidase (APX) in chloroplasts improve tolerance to water stress.

Creep Design of Type 316LN Stainless Steel by K-R Damage Theory (K-R 손상이론에 의한 316LN 스테인리스강의 크리프 설계)

  • Kim, U-Gon;Kim, Dae-Hwan;Ryu, U-Seok
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.25 no.2
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    • pp.296-303
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    • 2001
  • Kachanov-Rabotnov(K-R) creep damage theory was reviewed, and applied to design a creep curve for type 316LN stainless steel. Seven coefficients used in the theory, i.e., A, B, k, m, λ, r, and q were determined, and their physical meanings were analyzed clearly. In order to quantify a damage parameter ($\omega$), cavity amount was measured in the crept specimen taken from interrupted creep test with time variation, and then the amount was reflected into K-R damage equations. Coefficient λ, which is regarded as a creep tolerance feature of a material, increased with creep strain. Mater curve with λ=2.8 was well coincided with an experimental one to the full lifetime. The relationship between damage parameter and life fraction was matched with the theory at exponent ${\gamma}$=24 value. It is concluded that K-R damage equation was reliable as the modelling equation for type 316LN stainless steel. Coefficient data obtained from type 316LN stainless steel can be utilized for life prediction of operating material.

Impact Properties of New 3D Composites by Fiber Placement Processing (섬유 자동 배열에 의한 시로운 3D 복합재의 충격특성)

  • Song S-W;Lee C-H;Song J-E;Byun J-H;Um M-K
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2004.10a
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    • pp.171-174
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    • 2004
  • In order to improve the damage tolerance of the conventional laminated composites, three­dimensional fiber structures incorporated with stitching yams have been utilized in this study. From the newly developed process termed as TAPIS(TApe Placement Incorporated with Stitching), carbon/epoxy composites have been fabricated. Two-dimensional composites with the same stacking sequence as 3D counterparts have also been fabricated for the property comparison. To examine the damage resistance performance the low speed drop weight impact test has been adopted. For the assessment of damage after the impact loading, specimens were subjected to C-scan nondestructive inspection compression after impact(CAI) were also conducted to evaluate residual compressive strength. Although the damage area of 3D composites was greatly reduced$(30-40\%)$ compared with that of 2D composites, the CAI strength did not show drastic improvement.

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Impact Characteristics of Glass Fiber Reinforced Composite Curved Beams w.r.t. Pre-load (예 하중이 유리섬유 복합재료 곡선 보의 충격특성에 미치는 영향)

  • Lee, Seung-Min;Lim, Tae-Seong;Lee, Dai-Gil
    • Proceedings of the KSME Conference
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    • 2004.04a
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    • pp.162-167
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    • 2004
  • The low velocity impact characteristics of composite laminate curved beams are investigated to increase damage tolerance and reduce the deflection. Drop weight impact tests of the composite curved beam were performed with respect to pre-load, then the damage after impact was measured by macrography. Also, finite element analyses were performed using ABAQUS to investigate the stress state of composite curved beam with respect to pre-load and impact. From the investigation, it was found that pre-load of the composite curved beams had much influence on impact damage of the curved beam, which showed good agreement with the experiment results.

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Interferon-Stimulated Gene 15 in the Control of Cellular Responses to Genotoxic Stress

  • Jeon, Young Joo;Park, Jong Ho;Chung, Chin Ha
    • Molecules and Cells
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    • v.40 no.2
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    • pp.83-89
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    • 2017
  • Error-free replication and repair of DNA are pivotal to organisms for faithful transmission of their genetic information. Cells orchestrate complex signaling networks that sense and resolve DNA damage. Post-translational protein modifications by ubiquitin and ubiquitin-like proteins, including SUMO and NEDD8, are critically involved in DNA damage response (DDR) and DNA damage tolerance (DDT). The expression of interferon-stimulated gene 15 (ISG15), the first identified ubiquitin-like protein, has recently been shown to be induced under various DNA damage conditions, such as exposure to UV, camptothecin, and doxorubicin. Here we overview the recent findings on the role of ISG15 and its conjugation to target proteins (e.g., p53,$ {\Delta}Np63{\alpha}$, and PCNA) in the control of cellular responses to genotoxic stress, such as the inhibition of cell growth and tumorigenesis.

Low Temperature Tolerance of Panax quinquefolium (미국삼(Panax quinquefolium)의 저온 저항성에 관한 연구)

  • Lee, Jong-Chul;John, T.A.Proctor
    • Journal of Ginseng Research
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    • v.20 no.2
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    • pp.179-183
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    • 1996
  • One exotherm was detected in the intact ginseng seeds containing more than 35% water, but in seeds with 20% there was no exotherm. The shapes of exotherm were remarkably uniform without relation to water content above 35%. The temperature at the initiation of freezing varied from -3.5$^{\circ}C$ to -9.6$^{\circ}C$ with the different water content in the seeds, and the Initial temperature of freezing delayed with the decrease of water content. The resistance damage at low temperature appeared in order of maln body, rhizome, lateral root of 3-year-old yearling rhizome, and fine root of 3-year-old. Ginseng roots didn't receive any damage at -5$^{\circ}C$ for 24 hours. Otherwise they received serious damage below -1$0^{\circ}C$ even for 5 hours'exposure. Hence, alternative low temperature gave more severe damage compared to constant low temperature. This result suggests that the Possibility of receiving injury at low temperature was higher during the thawing season of the early spring than in the winter.

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