• Structural Engineering and Mechanics
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• 제18권6호
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• pp.769-790
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• 2004

The compressive behavior up to failure of short concrete members reinforced with fiber reinforced plastic (FRP) is investigated. Rectangular cross-sections are analysed by means of a simplified elastic model, able also to explain stress-concentration. The model allows one to evaluate the equivalent uniform confining pressure in ultimate conditions referred to the effective confined cross-section and to the effective stresses in FRP along the sides of section; consequently, it makes it possible to determine ultimate strain and the related bearing capacity of the confined member corresponding to FRP failure. The effect of local reinforcements constitute by single strips applied at corners before the continuous wrapping and the effect of round corners are also considered. Analytical results are compared to experimental values available in the literature.

• Computers and Concrete
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• 제13권2호
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• pp.235-253
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• 2014

The theoretical basis and the main results of a design procedure, which attempts to provide the optimal layout of ordinary reinforcement in prestressed concrete beams, subjected to bending moment and shear force are presented. The difficulties encountered in simulating the actual behaviour of prestressed concrete beam in presence of coupled forces bending moment - shear force are discussed; particular emphasis is put on plastic models and stress fields approaches. A unified model for reinforced and prestressed concrete beams under axial force - bending moment - shear force interaction is provided. This analytical model is validated against both experimental results collected in literature and nonlinear numerical analyses. Finally, for illustrating the applicability of the proposed procedure, an example of design for a full-scale prestressed concrete beam is shown.

• Membrane and Water Treatment
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• 제10권2호
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• pp.121-125
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• 2019

Chronic exposure to atrazine (ATR) raises concerns about adverse effects on reproductive functions. We tested our previously validated filtering device, the OBP-based filter, onto a biological model constituted of cultured swine granulosa cells treated for 48 h with media conditioned with 0.1 or $10{\mu}M$ ATR evaluating cell viability and steroidogenesis. The tested atrazine concentrations did not change granulosa cell viability and no filtering effects was observed following treatments with media prepared with differently filtered water. As for steroidogenesis, treatment of water with OBP-based filter containing $10{\mu}M$ atrazine completely suppressed the stimulatory effect of $10{\mu}M$ atrazine on progesterone production as well as the inhibitory effect of $0.1{\mu}M$ ATR on estradiol-$17{\beta}$ production by granulosa cells. Our data demonstrate that the impairment of steroidogenesis induced by ATR is effectively removed after water filtration in the experimental device thus suggesting potential use in biotechnological applications on living cells and/or organisms.

• 동력기계공학회지
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• 제2권2호
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• pp.20-26
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• 1998

Heat release data were obtained by analysis of cylinder diagrams from a test engine, naturally-aspirated small-size four-stroke DI diesel engine. These data were used to decide empirical coefficients of Whitehouse-Way's model, single zone combustion model. Finally, the comparison of calculated with experimental results was performed, and the accuracy of calculated versus experimental data of the model in predicting engine heat release and cylinder pressure was demonstrated.

• 한국터널지하공간학회 논문집
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• 제6권3호
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• pp.259-267
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• 2004

The practice of introducing and grouting reinforced fiber glass pipes or bar into the core to be excavated to maintain stable the tunnel face during excavation has been applied to many tunnels, where difficult geotechnical conditions are present, with good results in terms of safety and speed of works. This reinforcing technique, initially developed to be used jointly with the mechanical precut in clay, has been widely used with other geotechnical conditions as the only type of reinforcement or joined with other ground consolidation and/or reinforcement techniques (i.e. steel pipes or jet-grouting umbrella). At present same numerical researches have been carried out to find which are the real working conditions of the reinforcing elements but no final results have been obtained for the definition of the best design approaches. In this work the results of a three dimensional parametric numerical model is presented.

• BMB Reports
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• 제37권4호
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• pp.454-459
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• 2004

Experimental hyperoxia represents a suitable in vitro model to study some pathogenic mechanisms related to oxidative stress. Moreover, it allows the investigation of the molecular pathophysiology underlying oxygen therapy and toxicity. In this study, a modified experimental set up was adopted to accomplish a model of moderate hyperoxia (50% $O_2$, 96 h culture) to induce oxidative stress in the human leukemia cell line, U-937. Spectrophotometric measurements of mitochondrial respiratory enzyme activities, NMR spectroscopy of culture media, determination of antioxidant enzyme activities, and cell proliferation and differentiation assays were performed. The data showed that moderate hyperoxia in this myeloid cell line causes: i) intriguing alterations in the mitochondrial activities at the levels of succinate dehydrogenase and succinate-cytochrome c reductase; ii) induction of metabolic compensatory adaptations, with significant shift to glycolysis; iii) induction of different antioxidant enzyme activities; iv) significant cell growth inhibition and v) no significant apoptosis. This work will permit better characterization the mitochondrial damage induced by hyperoxia. In particular, the data showed a large increase in the succinate cytochrome c reductase activity, which could be a fundamental pathogenic mechanism at the basis of oxygen toxicity.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2011년도 춘계학술대회
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• pp.701-705
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• 2011

The paper reviews Cronbaha's coefficient to measure a single source of error. On the contrary to classical measurement theory, the generalizability study can be used in the social survey design to calculate Generalizability Index (GI) and Dependability Index (DI) for measuring multiple sources of errors of behavior evaluation. The study proposes application guidelines to implement R:($A{\times}B$) mixed models that are composed of random factor and fixed factor.

• Wind and Structures
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• 제17권6호
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• pp.629-646
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• 2013

One of the most common solutions adopted to reduce vibrations of skyscrapers due to wind or earthquake action is to add external damping devices to these structures, such as a TMD (Tuned Mass Damper) or TLCD (Tuned Liquid Column Damper). It is well known that a TLCD device introduces on the structure a nonlinear damping force whose effect decreases when the amplitude of its motion increases. The main objective of this paper is to describe a Hardware-in-the-Loop test able to validate the effectiveness of the TLCD by simulating the real behavior of a tower subjected to the combined action of wind and a TLCD, considering also the nonlinear effects associated with the damping device behavior. Within this test procedure a scaled TLCD physical model represents the hardware component while the building dynamics are reproduced using a numerical model based on a modal approach. Thanks to the Politecnico di Milano wind tunnel, wind forces acting on the building were calculated from the pressure distributions measured on a scale model. In addition, in the first part of the paper, a new method for evaluating the dissipating characteristics of a TLCD based on an energy approach is presented. This new methodology allows direct linking of the TLCD to be directly linked to the increased damping acting on the structure, facilitating the preliminary design of these devices.

• International Journal of Quality Innovation
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• 제3권2호
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• pp.13-28
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• 2002

Higher efficiency and effectiveness of Research & Development phases can be attained using advanced statistical methodologies. In this work statistical methodologies are combined with a deterministic approach to engineering design. In order to show the potentiality of such integration, a simple but effective example is presented. It concerns the problem of optimising the performances of a paper helicopter. The design of this simple device is not new in quality engineering literature and has been mainly used for educational purposes. Taking full advantage of fundamental engineering knowledge, an aerodynamic model is originally formulated in order to describe the flight of the helicopter. Screening experiments were necessary to get first estimates of model parameters. Subsequently, deterministic evaluations based on this model were necessary to set up further experimental phases needed to search (or a better design. Thanks to this integration of statistical and deterministic phases, a significant performance improvement is obtained. Moreover, the engineering knowledge かms out to be developed since an explanation of the “why” of better performances, although approximate, is achieved. The final design solution is robust in a broader sense, being both validated by experimental evidence and closely examined by engineering knowledge.

• BMB Reports
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• 제44권11호
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• pp.747-752
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• 2011

To investigate the effects of disulphide bond position on the salt resistance and lipopolysaccharide (LPS)-neutralizing activity of ${\alpha}$-helical homo-dimeric antimicrobial peptides (AMPs), we synthesized an ${\alpha}$-helical model peptide ($K_6L_4W_1$) and its homo-dimeric peptides (di-$K_6L_4W_1$-N, di-$K_6L_4W_1$-M, and di-$K_6L_4W_1$-C) with a disulphide bond at the N-terminus, the central position, and the C-terminus of the molecules, respectively. Unlike $K_6L_4W_1$ and di-$K_6L_4W_1$-M, the antimicrobial activity of di-$K_6L_4W_1$-N and di-$K_6L_4W_1$-C was unaffected by 150 mM NaCl. Both di-$K_6L_4W_1$-N and di-$K_6L_4W_1$-C caused much greater inhibitory effects on nitric oxide (NO) release in LPS-induced mouse macrophage RAW 264.7 cells, compared to di-$K_6L_4W_1$-M. Taken together, our results indicate that the presence of a disulphide bond at the N- or C-terminus of the molecule, rather than at the central position, is more effective when designing salt-resistant ${\alpha}$-helical homo-dimeric AMPs with potent antimicrobial and LPS-neutralizing activities.