• Title/Summary/Keyword: Environmental stresses

Search Result 850, Processing Time 0.027 seconds

Market Environmental Conditions and Reliability Testing for Electronic Equipments (전자기기의 시장환경조건과 신뢰성시험)

  • Tanaka, Hirokazu;Kim, Keun-Soo
    • Journal of the Microelectronics and Packaging Society
    • /
    • v.19 no.4
    • /
    • pp.1-5
    • /
    • 2012
  • The quality and performance of electronic parts and equipment are affected by various types of stresses. Thermal stress caused by changes in the ambient usage environment and mechanical stress from vibration shock during transportation can degrade both quality and performance. This paper gives an overview about recent researches for measuring market environmental conditions of electronic equipments.

Comparison of Environmental Stress Tolerance Between Lactobacillus fermentum Strains with High and Low Cell Surface Hydrophobicity

  • Li, Shao-Ji;Jeon, Jeong-Min;Hong, Sang-Won;So, Jae-Seong
    • Food Science and Biotechnology
    • /
    • v.17 no.2
    • /
    • pp.257-261
    • /
    • 2008
  • Previous studies have suggested a possible correlation between cell surface hydrophobicity (CSH) and stress tolerance in Bifidobacterium. In this study, the relationship was examined between CSH and environmental stress tolerance in Lactobacillus spp. By measuring the adhesion to hexadecane, 2 Lactobacillus fermentum strains- KLB 261 and KLB 231 were found to have high and low CSH, respectively. To measure their tolerance to various stresses, cells were subjected to salt (2 M NaCl), acid (pH 2), $H_2O_2$ (0.01 %, v/v), ethanol (20%, v/v), heat ($60^{\circ}C$), and cold ($-20^{\circ}C$). Compared with KLB 231, the hydrophobic KLB 261 was found to be much more resistant to the various stresses examined. After being subjected to different stresses for a period of time, KLB 261 and KLB 231 showed 50 and 0% survivability in 2 M NaCl, 108.2 and 0.6% in 0.01 %(v/v) $H_2O_2$, 40.2%(v/v), and 3.7% at $60^{\circ}C$ incubation, 4 and 0.6% at $-20^{\circ}C$, 12.9 and 0.1 % in pH 2, 33.8 and 0.2% in 20%(v/v) ethanol, respectively. Autoaggregation test and morphological observation were also conducted in an attempt to explain these differences. These results suggested that high CSH could strengthen the stress tolerance of lactobacilli.

Deformation Behavior of Existing Concrete-Faced Rockfill Dam due to Raising (증고에 따른 기존 CFRD 댐체의 변형거동)

  • Shin, Donghoon;Cho, Sungeun;Jeon, Jesung;Lee, Jongwook
    • Journal of the Korean GEO-environmental Society
    • /
    • v.8 no.6
    • /
    • pp.77-83
    • /
    • 2007
  • In this study, deformation behavior of existing concrete face rockfill dam, which is raised to a certain height to enhance storage capacity or to improve hydraulic and hydrologic stability, is examined using numerical analysis method. The results obtained from FEM analysis show a possibility that additional fill at downstram slope of existing CFRD dam body may lead undesirable deformations and stresses in existing dam body, especially in face concrete, such as settlements in upper part and bulging in lower part, excessive bending moments, and eventualy tensile cracks. Therefore, in designing multi-staged raising construction of CFRD, it is essential to consider deformations and stresses to be developed within and between exisiting dam body and added parts due to additional fill, and to prepare a proper measure to prevent abnormal deformations and stresses in the dam body including added parts.

  • PDF

Identification and Functional Characterization of the GALACTINOL SYNTHASE (MoGolS1) Gene in Melissa officinalis Plants

  • Kim, Jun-Hyeok;Hossain, Acktar Mohammad;Kim, Na-Hyun;Lee, Dong-Ho;Lee, Ho-Joung
    • Journal of Applied Biological Chemistry
    • /
    • v.54 no.4
    • /
    • pp.244-251
    • /
    • 2011
  • Galactinol and rafinose accumulation in plants is associated with stressful environmental conditions such as cold, heat, or dehydration by the action of galactinols synthase (GolS) in the raffinose family of oligosaccharides biosynthetic pathway from UDP-galactose. Moreover, several reports mentioned that GolS transcription is up regulated by various environmental stresses like cold, heat, dehydration. Therefore, to determine whether MoGolS1 was induced with the abiotic stress we analyzed the expression pattern of the gene under various abiotic stresses like heat, cold, abscisic acid, sucrose and salt concentration in the lemon balm plants grown in standard MS medium. The MoGolS1 gene was 981-bp in length encoding 326 amino acids in its sequence and shared 77 and 76% sequence similarity with Arabidopsis thaliana galactinol synthase4 (AtGolS4) and AtGolS1 genes respectively. The MoGolS1 gene was strongly expressed by the abiotic stress induced by sucrose, ABA or heat shock. It was also expressed in responses to cold, Identification and Functional Characterization of the GALACTINOL SYNTHASgene induction with various stresses may be possible for itscrucial function in abiotic stress tolerance in plants, providing a good engineering target for genetic engineering.

Numerical modeling of brittle failure of the overstressed rock mass around deep tunnel (심부 터널 주변 과응력 암반의 취성파괴 수치모델링)

  • Lee, Kun-Chai;Moon, Hyun-Koo
    • Journal of Korean Tunnelling and Underground Space Association
    • /
    • v.18 no.5
    • /
    • pp.469-485
    • /
    • 2016
  • The failure of rock mass around deep tunnel, different from shallow tunnel largely affected by discontinuities, is dominated by magnitudes and directions of stresses, and the failures dominated by stresses can be divided into ductile and brittle features according to the conditions of stresses and the characteristics of rock mass. It is important to know the range and the depth of the V-shaped notch type failure resulted from the brittle failure, such as spalling, slabbing and rock burst, because they are the main factors for the design of excavation and support of deep tunnels. The main features of brittle failure are that it consists of cohesion loss and friction mobilization according to the stress condition, and is progressive. In this paper, a three-dimensional numerical model has been developed in order to simulate the brittle behavior of rock mass around deep tunnel by introducing the bi-linear failure envelope cut off, elastic-elastoplastic coupling and gradual spread of elastoplastic regions. By performing a series of numerical analyses, it is shown that the depths of failure estimated by this model coincide with an empirical relation from a case study.

A Study on the Stability Estimation Procedure for Reinforced Pillar of Twin Tunnel (병설터널 보강 필라의 안정성 평가방법에 관한 연구)

  • Baek, Seungcheol;Jang, Busik;Lee, Taegyu;Lee, Sungmin;Hwang, Jungsoon
    • Journal of the Korean GEO-environmental Society
    • /
    • v.10 no.7
    • /
    • pp.81-91
    • /
    • 2009
  • Recently, twin-tunnel is often designed in the aspects of disaster prevention and economical reasons. However, the design cases and the studies are relatively insufficient. By the twin-tunnel excavation, deviate stresses of pillar between tunnels are increased and the increased stresses induce the instability of the twin-tunnel. In this study, numerical analyses about the twin-tunnel behaviour were conducted with varying ground strength, width of pillar and depth of earth cover and a series of regression analyses were carried out by using the results of numerical analyses for the twin-tunnel. Based on the numerical analyses, an estimation method of derived stresses is suggested through the regression analyses. Also, based on the results of regression analyses, an quantitative estimation method considering the reinforcement effects is also suggested. Then various parametric studies were conducted to be considered the reinforcement type and various design parameters. Finally, the efficiency of the suggested method based on the Hoek-Brown Failure Criterion is verified through the results of parametric studies.

  • PDF

Design Methodology of Gap Slab for Post-Tensioned Prestressed Concrete Pavement (포스트텐션 콘크리트 포장의 Gap Slab 설계 방안)

  • Park, Hee-Beom;Kim, Seong-Min;Shim, Jae-Soo
    • International Journal of Highway Engineering
    • /
    • v.12 no.2
    • /
    • pp.137-146
    • /
    • 2010
  • This study was conducted to develop the design methodology of gap slabs for the post-tensioned concrete pavement (PTCP). The gap slabs were considered as unbonded, half bonded, and bonded types. According to the types of the gap slabs, the curling stresses were investigated first under the environmental loads. The stresses due to the vehicle loads were analyzed considering both the single and tandem axles. The method to calculate the prestressing amount was suggested by comparing the combined stresses due to both loads and the allowable tensile stress of concrete. The prestressing amount for the unbonded type gap slab could be designed by considering only the gap slab; however, for the half bonded and bonded gap slabs, the whole PTCP slab should be analyzed to properly design the prestressing amount.