• Title/Summary/Keyword: stress evolution

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The Evolution of Marketing Thought and Marketing Communication: The Perspective of Relationship Marketing (마케팅 사고의 변천과 마케팅 커뮤니케이션 : 관계 마케팅 관점)

  • Hwang, Byung-Il
    • Korean Business Review
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    • v.12
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    • pp.1-27
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    • 1999
  • The author focus on the role of IMC(integrated marketing communication)that is important for increase of relationship equity value, stress on the integration of IMC and PR in relationship marketing. This paper present as follow. The first, marketing thought have evolved through market competition situation at a market segmentation level perspective, and the concept of relationship equity is necessary to individual marketing or relationship marketing. The second, firm should identify profitable customer, build strong relationship for relationship equity, based on customer equity and life time value in customer market. The third, IMC needs integration with PR for relationship building of stakeholder including customer market at a point of view of corporate equity. Finally, this article offer discussion about implications of integration IMC and PR for future study.

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Global Functional Analysis of Butanol-Sensitive Escherichia coli and Its Evolved Butanol-Tolerant Strain

  • Jeong, Haeyoung;Lee, Seung-Won;Kim, Sun Hong;Kim, Eun-Youn;Kim, Sinyeon;Yoon, Sung Ho
    • Journal of Microbiology and Biotechnology
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    • v.27 no.6
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    • pp.1171-1179
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    • 2017
  • Butanol is a promising alternative to ethanol and is desirable for use in transportation fuels and additives to gasoline and diesel fuels. Microbial production of butanol is challenging primarily because of its toxicity and low titer of production. Herein, we compared the transcriptome and phenome of wild-type Escherichia coli and its butanol-tolerant evolved strain to understand the global cellular physiology and metabolism responsible for butanol tolerance. When the ancestral butanol-sensitive E. coli was exposed to butanol, gene activities involved in respiratory mechanisms and oxidative stress were highly perturbed. Intriguingly, the evolved butanol-tolerant strain behaved similarly in both the absence and presence of butanol. Among the mutations occurring in the evolved strain, cis-regulatory mutations may be the cause of butanol tolerance. This study provides a foundation for the rational design of the metabolic and regulatory pathways for enhanced biofuel production.

Dynamic Recrystallization of Medium Carbon Steels (중탄소강의 동적 재결정에 관한 연구)

  • Kim S. I.;Han C. H.;Yoo Y. C.;Lee D. R.;Ju U. Y.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2000.10a
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    • pp.33-36
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    • 2000
  • The dynamic recrystallization (DRX) of medium carbon steels (SCM 440 and POSMA45) was studied with torsion test in the temperature range of $900-1100^{\circ}C$ and the strain rate range of $5.0x10^{-2}\;-\;5.0x10^0/sec$. To establish the quantitative equations for DRX, the evolution of flow stress curve with strain was analyzed. The critical strain (${\varepsilon}_c$) and strain for maximum softening rate ( ${\varepsilon}^{*}$) could be confirmed by the analysis of work hardening rate ($d{\sigma}/d{\varepsilon}\;=\; \theta$). The volume fraction of dynamic recrystallization ($X_{DRX}$) as a function of processing variables, such as strain rate ( $\dot{\varepsilon}$ ), temperature (T), and strain ( $\varepsilon$ ) were established using the ${\varepsilon}_c$ and ${\varepsilon}^{*}$. For the exact prediction, the ${\varepsilon}_c$, ${\varepsilon}^{*}$ and Avrami' exponent (m') were quantitatively expressed by dimensionless parameter, Z/A respectively. The transformation-effective strain-temperature curve for DRX could be composed. It was found that the calculated results were agreed with the experimental data for the steels at any deformation conditions.

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Study on fracture behavior of polypropylene fiber reinforced concrete with bending beam test and digital speckle method

  • Cao, Peng;Feng, Decheng;Zhou, Changjun;Zuo, Wenxin
    • Computers and Concrete
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    • v.14 no.5
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    • pp.527-546
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    • 2014
  • Portland cement concrete, which has higher strength and stiffness than asphalt concrete, has been widely applied on pavements. However, the brittle fracture characteristic of cement concrete restricts its application in highway pavement construction. Since the polypropylene fiber can improve the fracture toughness of cement concrete, Polypropylene Fiber-Reinforced Concrete (PFRC) is attracting more and more attention in civil engineering. In order to study the effect of polypropylene fiber on the generation and evolution process of the local deformation band in concrete, a series of three-point bending tests were performed using the new technology of the digital speckle correlation method for FRC notched beams with different volumetric contents of polypropylene fiber. The modified Double-K model was utilized for the first time to calculate the stress intensity factors of instability and crack initiation of fiber-reinforced concrete beams. The results indicate that the polypropylene fiber can enhance the fracture toughness. Based on the modified Double-K fracture theory, the maximum fracture energy of concrete with 3.2% fiber (in volume) is 47 times higher than the plain concrete. No effort of fiber content on the strength of the concrete was found. Meanwhile to balance the strength and resistant fracture toughness, concrete with 1.6% fiber is recommended to be applied in pavement construction.

Magnetohydrodynamic Simulations of Barred Galaxies

  • Kim, Woong-Tae;Stone, James M.
    • The Bulletin of The Korean Astronomical Society
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    • v.37 no.1
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    • pp.38.2-38.2
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    • 2012
  • We use two-dimensional high-resolution MHD simulations to investigate the effects of magnetic fields on the formation and evolution of such substructures as well as on the mass inflow rates to the galaxy center. We find that there exists an outermost x1-orbit relative to which gaseous responses to an imposed stellar bar potential are completely different between inside and outside. Inside this orbit, gas is shocked into dust lanes and infalls to form a nuclear ring. Magnetic fields are compressed in dust lanes, reducing their peak density. Magnetic stress removes further angular momentum of the gas at the shocks and leads to a smaller and more centrally distributed ring, resulting in the mass inflow rates larger, by more than two orders of magnitude, than in the unmagnetized counterparts. Outside the outermost x1-orbit, on the other hand, an MHD dynamo operates near the corotation and bar-end regions, efficiently amplifying magnetic fields. The amplified fields shape into trailing magnetic arms with strong fields and low density. The base of the magnetic arms have a thin layer in which magnetic fields with opposite polarity reconnect via a tearing-mode instability. This produces numerous magnetic islands with large density which propagate along the arms to turn the outer disk into a highly chaotic state.

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Differentially Expressed Genes under Cold Acclimation in Physcomitrella patens

  • Sun, Ming-Ming;Li, Lin-Hui;Xie, Hua;Ma, Rong-Cai;He, Yi-Kun
    • BMB Reports
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    • v.40 no.6
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    • pp.986-1001
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    • 2007
  • Cold acclimation improves freezing tolerance in plants. In higher plants, many advances have been made toward identifying the signaling and regulatory pathways that direct the low-temperature stress response; however, similar insights have not yet been gained for simple nonvascular plants, such as bryophytes. To elucidate the pathways that regulate cold acclimation in bryophytes, we used two PCR-based differential screening techniques, cDNA amplified fragment length polymorphism (cDNA-AFLP) and suppression subtractive hybridization (SSH), to isolate 510 ESTs that are differentially expressed during cold acclimation in Physcomitrella patens. We used realtime RT-PCR to further analyze expression of 29 of these transcripts during cold acclimation. Our results show that cold acclimation in the bryophyte Physcomitrella patens is not only largely similar to higher plants but also displays distinct differences, suggests significant alteration during the evolution of land plants.

Crystal Plasticity Simulation of Ti-6Al-4V Under Fretting Fatigue (프레팅 피로를 받는 Ti-6Al-4V의 결정소성 시뮬레이션)

  • Goh Chung Hyun;Lee Kee Seok;Ko Jun Bin
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.29 no.4 s.235
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    • pp.511-517
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    • 2005
  • Fretting fatigue is often the root cause of the nucleation of cracks at attachments of structural components. Since fretting fatigue damage accumulation occurs over relatively small volumes, the subsurface cyclic plastic strain is expected to be rather non-uniformly distributed in polycrystalline materials. The scale of the cyclic plasticity and the damage process zones is often on the order of microstructure dimensions. Fretting damage analyses using cyclic crystal plasticity constitutive models have the potential to account for the influence of size, morphology, and crystallographic orientation of grains on fretting damage evolution. Two-dimensional plane strain simulations of fretting fatigue are performed using the cyclic properties of Ti-6Al-4V. The crystal plasticity simulations are compared to an initially isotropic $J_{2}$ theory with nonlinear kinematic hardening as well as to experiments. The influence of initially isotropic versus textured microstructure in the presence of crystallographic slip is studied.

Time-Temperature Superposition Behavior for Accelerated Fatigue Lifetime Testing of Polycarbonate(PC) (폴리카보네이트(PC)의 가속 피로수명 시험을 위한 시간-온도 호환성)

  • Kim Gyu-Ho
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.30 no.8 s.251
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    • pp.976-984
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    • 2006
  • Time-temperature superposition has been studied to determine the long-term fatigue life over millions of cycles for glassy polymers. π le superposition is supposed to make an accelerated lifetime testing (ALT) technique possible. Dog-bone shaped specimens made of carbon filled Polycarbonate (PC) were tested under fatigue, based on the stress-lifetime approach (S-N curve). Fatigue-induced localized yield-like deformation is considered as the defect leading to fatigue and its evolution behavior is characterized by a modified energy activation model in which temperature is considered as fatigue acceleration factor. This model allows the reduced time concept to account for effects of different temperature in short-term fatigue data to determine long-term fatigue life through the use of time-temperature superposition that is applicable under a low frequency and isothermal conditions. The experimental results validated that the proposed technique could be a possible method for accelerated lifetime testing (ALT) of time-dependent polymeric materials.

Changes of Hemodynamic Characteristics during Angulated Stenting in the Stenosed Coronary (관상동맥 협착부에 각이진 스텐트 시술시 혈류역학적 특성변화)

  • Suh Sang-Ho;Cho Min-Tae;Kwon Hyuck-Moon;Lee Byung-Kwon
    • Proceedings of the KSME Conference
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    • 2002.08a
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    • pp.717-720
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    • 2002
  • The present study is to evaluate the performances of flow velocity and wall shear stress in the stenosed coronary artery using human in vivo hemodynamic Parameters and computer simulation. Initial and follow-up coronary angiographics in the patients with angulated coronary stenosis are performed. Follow-up coronary angiogram demonstrated significant difference in the percent of diameter in the stenosed coronary between two groups ($Group\;1:\;40.3{\%},\;Group\;2:\;25.5{\%}$). Flow-velocity wave obtained from in vivo intracoronary Doppler ultrasound data is used for the boundary condition for the computer simulation. Spatial and temporal variations of flow velocity vector and recirculation area are drawn throughout the selected segment of coronary models. The WSS of pre- and post-intracoronary stenting are calculated from three-dimensional computer simulation. Then negative shear stresses area on 3D simulation we noted on the inner wall of the post-stenotic area before stenting. The negative WSS is disappeared after stenting. High spatial and temporal WSS before stenting fell into within physiologic WSS after stenting. This finding was prominent in Model 2. The present study suggest that hemodynamic forces exerted by pulsatile coronary circulation termed WSS might affect on the evolution of atherosclerosis within the angulated vascular curvature. The local recirculation area which has low or negative WSS, might lead to progression of atherosclerosis.

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An Experimental Study of Turbulent Uniform Shear Flow in a Nearly Two-Dimensional $90^{\circ}$ Curved Duct (II) - Turbulent Flow Field- (2차원 $90^{\circ}$ 곡관에서 균일전단류의 특성에 대한 실험적 연구 (2) -난류유동장-)

  • 임효재;성형진;정명균
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.3
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    • pp.846-857
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    • 1995
  • An experimental study is made of turbulent shear flows in a nearly two-dimensional 90.deg. curved duct by using the hot-wire anemometer. The Reynolds normal and shear stresses, triple velocity products, integral length scales, Taylor micro length scales and dissipation length scales are measured and analyzed. For a positive shear at the inlet, the afore-mentioned turbulence quantities are all suppressed. However, when the inlet shear flow is negative, they are augmented, i.e., the convex curvature suppresses the turbulence whereas the concave curvature augments it. It is found that the curvature effects are rather sensitive to the triple velocity products than the Reynolds stresses. The evolution of turbulence under the curvature with the different shear conditions is well described by the modified curvature parameter S' and the non-dimensional development time ${\tau}$.'