• Journal of Mechanical Science and Technology
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• 제15권5호
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• pp.613-622
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• 2001

Interaction of blood flow and leaflet behavior in a bileaflet mechanical heart valve was investigated using computational analysis. Blood flows of a Newtonian fluid and a non-Newtonian fluid with Carreau model were modeled as pulsatile, laminar, and incompressible. A finite volume computational fluid dynamics code and a finite element structure dynamics code were used concurrently to solve the flow and structure equations, respectively, where the two equations were strongly coupled. Physiologic ventricular and aortic pressure waveforms were used as flow boundary conditions. Flow fields, leaflet behaviors, and shear stresses with time were obtained for Newtonian and non-Newtonian fluid cases. At the fully opened phase three jets through the leaflets were found and large vortices were present in the sinus area. At the very final stage of the closing phase, the angular velocity of the leaflet was enormously large. Large shear stress was found on leaflet tips and in the orifice region between two leaflets at the final stage of closing phase. This method using fluid-structure interaction turned out to be a useful tool to analyze the different designs of existing and future bileaflet valves.

• 한국가시화정보학회지
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• 제12권2호
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• pp.18-22
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• 2014

Caenorhabditis elegans (C. elegans) is an undulatory nematode which exhibits two distinct locomotion types of swimming and crawling. Although in its natural habitat C. elegans lives in a non-Newtonian fluidic environment, our current understanding has been limited to the behavior of C. elegans in a simple Newtonian fluid. Here, we present some experimental results on the penetrating behavior of C. elegans at the interface from liquid to solid environment. Once C. elegans, which otherwise swims freely in a liquid, makes a contact to the solid gel boundary, it begins to penetrate vertically to the surface by changing its stroke motion characterized by a stiffer body shape and a slow stroke frequency. The particle image velocimetry (PIV) analysis reveals the flow streamlines produced by the stroke of worm. For the worm that crawls on a solid surface, we utilize a technique of traction force microscopy (TFM) to find that the crawling nematode forms localized force islands along the body where makes direct contacts to the gel surface.

• Nuclear Engineering and Technology
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• 제49권8호
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• pp.1636-1644
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• 2017

The main purpose of this article is to describe the magnetohydrodynamic stagnation point flow of Walter-B nanofluid over a stretching sheet. The phenomena of heat and mass transfer are based on the involvement of thermal radiation and chemical reaction. Characteristics of Newtonian heating are given special attention. The Brownian motion and thermophoresis models are introduced in the temperature and concentration expressions. Appropriate variables are implemented for the transformation of partial differential frameworks into sets of ordinary differential equations. Plots for velocity, temperature, and nanoparticle concentration are displayed and analyzed for governing parameters. The skin friction coefficient and local Nusselt and Sherwood numbers are studied using numerical values. The temperature and heat transfer rate are enhanced within the frame of the thermal conjugate parameter.

• 천문학회보
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• 제42권2호
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• pp.84.2-84.2
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• 2017

The pilot study of SLGT (Superconducting Low-frequency Gravitational-wave Telescope) is being performed by KKN (KASI-KISTI-NIMS) collaboration. Among environmental noise sources, Newtonian noise (NN) is one of the most challenging obstacles in order to achieve a good sensitivity in low frequency below 10Hz for terrestrial gravitational wave (GW) detectors. So we should mitigate them for operating the SLGT to detect GWs on the ground. In this poster, we discuss the NNs and its mitigation for SLGT.

• Journal of Astronomy and Space Sciences
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• 제38권1호
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• pp.39-44
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• 2021

In the general accretion disk model theory, the accretion disk surrounding an astronomical object comprises fluid rings obeying Keplerian motion. However, we should consider relativistic and rotational effects as we close in toward the center of accretion disk surrounding spinning compact massive objects such as a black hole or a neutron star. In this study, we explore the geometry of the inner portion of the accretion disk in the context of Mukhopadhyay's pseudo-Newtonian potential approximation for the full general relativity theory. We found that the shape of the accretion disk "puffs up" or becomes thicker and the luminosity of the disk could exceed the Eddington luminosity near the surface of the compact spinning black hole.

• 영어영문학
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• 제58권4호
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• pp.723-752
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• 2012

Although his mythic poetry deals with the fall and resurrection of Albion as the origin of humankind, William Blake (1757-1827) simultaneously links it to the professionalization and unification of disciplinary knowledge itself. He particularly takes a great interest in the cross-referential relation of poetry to science. He argues for the communication of poetry and science on equal footing with each other without the former's prioritization over the latter, or vice versa. In his works Vala, or The Four Zoas (1797-1807) and Jerusalem: The Emanation of the Giant Albion (1804-1820), on which I focus in this essay, Blake's primary problematic is to display strong conflicts among different systems of knowledge. I approach this issue in light of the ideological clash of Newtonian thought, Romantic thought, and postmodern thought. In his poetry, Blake thematizes the very clashes of these different thought patterns. From the standpoint of Romantic thought, first of all, Blake problematizes Newtonian Enlightenment. He criticizes abstract universalization both in poetry and science, which Urizen, one of four Zoas, propagates. Protesting against Urizen's Newtonism, Los values "living form." Thus, Blake demonstrates, through this figure, that poetic imagination and scientific organicism are discursively communicative. Blake, however, also questions the network of Romantic science and Romantic poetry so as to suggest what current critics would call postmodern thought. Blakean postmodernism pursues the self-similarity of organic structure in science and poetry. Precisely, Blake sees polypus as a proliferation of organic body; he arranges four Zoas' self-repetitive stories in a non-linear way. Blake aspires for the conflicting coexistence of different thought patterns.

• 식품보건융합연구
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• 제8권5호
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• pp.11-20
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• 2022

Honey was diluted with different percentages of water and was analysed rheologically at room temperature of 27℃. The rheological profiles of pure and impure honey samples were measured at low shear rates (0.01-4.16s^-1). This work developed a structural kinetic model, which correlated well with the rheological data. The new model was used to categorise honey samples using their average molecular weights as one of the distinctive properties. Also, the kinetics order in the new model predicts the number of active components in the "honey" undergoing deformation. Honey produced third order kinetics to depict the monomers, oligomers and water content in honey. Pure honey exhibits peculiar non-Newtonian rheological behaviour. The behaviour of water is Newtonian. Dilution of honey with different percentages of water turns the resulting fluid Newtonian from 10% dilution with water. This study analysed the antibacterial activities of honey and serially adulterated samples against Staphylococcus aureus and Pseudomonas aeruginosa. The antibacterial analyses of honey were conducted using Kirby Bauer's well diffusion method. The results indicated that pure honey exhibited a zone of inhibition against both organisms. Also, the diameter of the zone of inhibition decreased with increasing dilution of honey, suggesting a correlation with the rheological method.

• 한국화재소방학회논문지
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• 제5권2호
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• pp.21-35
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• 1991

As a part of studies of drag reduction phenomenon, at the entrance flow region of abrupt contraction tube flowing water, dilute and concentrated drag reducing polymer solutions contraction losses are estimated experimentally. Futher more, entrance lengths are considered theoretically and are measured experimentally. In the present experiment, fluid temperature is fixed l$0^{\circ}C$ and flow rates are 3,000

• Journal of Nutrition and Health
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• 제10권3호
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• pp.1-6
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• 1977

Flow properties of heated edible oils, such as soybean, rapeseed, rice bran, corn and perilla oils, were measured with Maron-Belner type capillary viscometer. These oils were heated at $180{\pm}5^{\circ}C$ (general cooking temperature) for $5{\sim}20$ hours except soybean oils ($5{\sim}40$ hours). Fluidities of these heated oils except rice bran oil were decreased according to heating time and decreasing ratio of fluidity was outstanding after 15 hour heating in corn oil and 20 hours heating in soybean and perilla oils. All the oils examined in this experiments except rice bran oil showed non-Newtonian motion after 15 hour hinting at high shear stress and Newtonian motion at less than 10 hour heating. In the soybean oil non-Newtonian flow property was outstanding after 30 hour heating at $180{\pm}5^{\circ}C$. Rice bran oil exhibit characteristic flow property, that is, non heated rice bran oil has lowest fluidity but heated one has highest fluidity compared to other oils examined in this experiment. Change of fluidity with extension of heating time was not detected and non heated rice bran oil showed non-Newtonian motion.

• 제어로봇시스템학회논문지
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• 제20권12호
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• pp.1209-1216
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• 2014

This paper copes with control design for unmanned aerial vehicle transportation system. Moving pendulum dynamics of slung-load system is derived using two methods: Udwadia-Kalaba equation and Newtonian approach. PID controller is applied to Udwadia-Kalaba equation model for structural consistency and linear quadratic Gaussian / Loop Transfer Recovery (LQG/LTR) technique is employed for Newtonian model with minimal state-space realization. Characteristics of PID and LQG/LTR controller are compared, and two controllers are combined to compensate the drawbacks of each other. Numerical simulation is set for two cases and conducted to evaluate performance of designed controllers. The result proves that combination of LQG/LTR and PID control performs stable and robust.