• Journal of the Earthquake Engineering Society of Korea
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• v.11 no.2 s.54
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• pp.19-26
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• 2007

This paper presents the results of experimental studies of the mechanical characteristics of the Coil Spring and Viscous Damper system. The Coil Spring and Viscous Damper systems were selected for the isolation of Emergency Diesel Generator (EDG) which is located in Nuclear Power Plant (NPP). The Coil Spring and Viscous Damper systems were developed for the operating vibration isolation and seismic isolation for scaled Model EDG System. The damping properties of the viscous damper changes as the variation of velocity. Through this research nonlinear damping characteristics and the effective stiffness of coil spring and viscous damper system were evaluated.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.246-251
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• 2003

This paper presents an experimental study on the energy dissipation characteristics of viscous damping wall (VDW). VDW is consisted of a plate floating in a thin case made of steel plated filled with highly viscous silicone oil. Because VDW demonstrates both viscous damping and stiffness characteristics, the viscous resisting force can be expressed as the sum of velocity dependant viscous damping force and displacement dependant restoring force. The viscous resisting force and energy absorbing capacity can be easily adjusted by changing three factors, i.e. viscosity of the fluid, gap distance and area of the wall plates. VDW was tested using a series of harmonic (sinusoidal) displacement history having different frequency and amplitude and the force-displacement relationship was recorded. The relationship between dissipated energy with three factors and the influence of exciting frequency on resisting force were Investigated

• Journal of the korean society of oceanography
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• v.35 no.2
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• pp.78-88
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• 2000

A weakly viscous wave and an approximate variational principle in viscous fluids are introduced, with which we can interpret the fundamentals such as how viscosity dissipation occurs with time elapse, and how the free surface boundary layer exists at the wavy surface in weakly viscous fluids. As an application, responses of a spherical buoy on the weakly viscous capillary gravity wave are investigated to show the viscosity effects. At the end, surfactant problems are briefly reviewed with the view of short viscous waves as expected future applications.

• Steel and Composite Structures
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• v.34 no.4
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• pp.487-497
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• 2020

During the last few decades, fluid viscous dampers have been significantly improved in terms of performance and reliability. Viscous dampers dissipate the input energy into heat and the increased temperature may damage internal seals of the damper. As a result, thermal compensation is crucial for almost all fluid viscous dampers. In this study, while referring to the main working principles of the recently developed bypass viscous damper in Iran, a comprehensive case study is conducted on a RC building having diagonal braces equipped with such viscous dampers. Experimental results of a small-scale bypass viscous damper is presented and it is shown that the currently available simplified Maxwell models can simulate behavior of the bypass viscous damper with good accuracy. Using a case study, contribution of bypass viscous dampers to seismic behavior of structural and non-structural elements are investigated. A designed procedure is adopted to increase damping ratio of the building from 3% to 15%. In this way, reductions of 25% and 13% in the required concrete and steel rebar materials have been achieved. From nonlinear time history analyses, it is observed that bypass viscous dampers can greatly improve seismic behavior of structural elements and non-structural elements.

• Journal of Neurogastroenterology and Motility
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• v.24 no.4
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• pp.570-576
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• 2018

Background/Aims Swallows with viscous or solid boluses in different body positions alter esophageal manometry patterns. Limitations of previous studies include lack of standardized viscous substrates and the need for chewing prior to swallowing solid boluses. We hypothesize that high-resolution impedance manometry (HRiM) using standardized viscous and super-viscous swallows in supine and upright positions improves sensitivity for detecting esophageal motility abnormalities when compared with traditional saline swallows. To establish normative values for these novel substrates, we recruited healthy volunteers and performed HRiM. Methods Standardized viscous and super-viscous substrates were prepared using "Thick-It" food thickener and a rotational viscometer. All swallows were administered in 5-mL increments in both supine and upright positions. HRiM metrics and impedance (bolus transit) were calculated. We used a paired two-tailed t test to compare all metrics by position and substrate. Results The 5-g, 7-g, and 10-g substrates measured 5000, 36 200, and 64 $700mPa{\cdot}sec$, respectively. In 18 volunteers, we observed that the integrated relaxation pressure was lower when upright than when supine for all substrates (P < 0.01). The 10-g substrate significantly increased integrated relaxation pressure when compared to saline in the supine position (P < 0.01). Substrates and positions also affected distal contractile integral, distal latency, and impedance values. Conclusions We examined HRiM values using novel standardized viscous and super-viscous substrates in healthy subjects for both supine and upright positions. We found that viscosity and position affected HRiM Chicago metrics and have potential to increase the sensitivity of esophageal manometry.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2006.03a
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• pp.471-478
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• 2006

This paper presents the results of experimental studies of the mechanical characteristics of the Coil Spring and Viscous Damper system. The Coil Spring and Viscous Damper systems were selected for the isolation of Emergency Diesel Generator (EDG) which is located in Nuclear Power Plant (NPP). The Coil Spring and Viscous Damper systems were developed for, the operating vibration isolation and seismic isolation for scaled Model EDG System. The damping properties of the viscous damper changes as the variation of velocity. As a results, nonlinear damping characteristics of viscous damper system were evaluated.

• 한국전산유체공학회:학술대회논문집
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• 1996.05a
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• pp.40-45
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• 1996

This paper discribes the viscous interaction of Hypersonic Wedge Flows using Roe FDS and AUSM+. For this purpose we developed the frozen and the equilibrium code and numerically simulated the viscous interaction by changing the surface temperature and the mach number. We used curve fitting data in NASA Reference Publication 1181, 1260 to calculate equilibrium properties. We compare the equilibrium flow with the frozen flow. We conclude that the mach number and the surface temperature are significant parameters, as the surface temperature and the mach number increase the viscous interaction becomes stronger, and we must consider high-temperature effects in hypersonic flow

• Journal of Ocean Engineering and Technology
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• v.14 no.2
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• pp.112-116
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• 2000

To determine a preliminary hull form with a minimum viscous resistance this study considers the systematic variations of full form and calculations of the viscous resistance for varied hull forms. A preliminary hull form can be determined from a parametric study of viscous resistance.

• Journal of fish pathology
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• v.18 no.2
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• pp.167-178
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• 2005

Streptococcus iniae is one of the major bacterial pathogens of cultured olive flounder, Paralichthys olivaceus in Korea. This study was carried out to investigate the interaction between morphological characteristics and immune response such as phagocytosis and serum killing activity. They were differentiated phenotypically into two groups, the viscous colonies and the non-viscous colonies, but the strains in both groups were similar in physiological and biochemical characteristics. Electron microscopic examination of the viscous form revealed thick, electron-dense exopolysaccharide materials surrounding polycationic ferritin-stained cells, while the exopolysaccharide material was absent around the non-viscous form of S. iniae. The viscous type strains were disclosed more virulent than those of non-viscous type for olive flounder. The viscous strains were resistant to normal serum killing activity, while the non-viscous strains were susceptible to bactericidal activity of normal serum from olive flounder. The viscous strains were more resistant to opsonophagocytosis and decreased the chemiluminescence response of head kidney macrophages of olive flounder. All of the tested non-viscous S. iniae strains were efficiently destroyed by the macrophage after phagocytosis. Both the viscous and the non-viscous strains invaded and replicated in cultured fish cell line (CHSE-2l4). This cellular invasion may contribute to the pathogenesis of invasive S. iniae infection.

• 한국방재학회:학술대회논문집
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• 2007.02a
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• pp.140-143
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• 2007

A continuing elevated bridge is replaced with mass-spring system model, and a part of the bridge is cut out as an analytical area. A viscous boundary is installed at both ends, and dynamic analyses are carried out changing the wave velocity of the viscous boundary, The result is compared with a result of a very long model corresponding to the solution with infinite length. A wave velocity is chosen so that the good performance of a viscous boundary is exhibited. The parametric analyses are carried out changing the model of various structural properties, and an approximation expression is suggested to obtain the wave velocity easily for setting a viscous boundary.