The Experts below are selected from a list of 303 Experts worldwide ranked by ideXlab platform
Kwang-phil Park - One of the best experts on this subject based on the ideXlab platform.
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The flexible multibody dynamics of a floating offshore wind turbine in marine operations
Ships and Offshore Structures, 2016Co-Authors: Kwang-phil Park, Namkug KuAbstract:ABSTRACTIn this paper, a dynamic response analysis of a floating offshore wind turbine is performed during the rotor rotation under wind and wave loads after the turbine was installed on a floating platform.The floating offshore wind turbine is modelled as a system that consists of the floating platform, a tower, a nacelle, a hub, and three blades. Flexible multibody dynamics is employed in constructing the equations dealing with motion for the floating offshore wind turbine in the dynamic response analysis. The tower and the blades are constructed as flexible bodies by using the three-dimensional beam element. The external Forces acting on the floating platform included the Hydrostatic Force, the hydrodynamic Force, and the mooring Force. Then, aerodynamic Force was calculated based on the blade element momentum theory, and was applied to the blades.Using the wave and wind conditions that are generally required to operate a 5-MW offshore wind turbine, a numerical simulation was performed to determine the...
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computation of nonlinear Hydrostatic Force and position of a floating structure considering the coupled large inclined angles
Korean Journal of Computational Design and Engineering, 2016Co-Authors: Namkug Ku, Kwang-phil ParkAbstract:Received 21 December 2015; received in revised form 19 January 2016; accepted 20 January 2016ABSTRACTWhen ships and offshore plants are flooded or the floating crane is equipped with a heavyobject, these floating structures are excessively inclined. In this case, immersion, heel, and trimaffecting the Hydrostatic restoration performance are very large and are coupled each other. Inthis paper, in order to calculate a static equilibrium position of floating structures with exces-sive inclination, the nonlinear governing equations were constructed by sequential linearization.In the governing equation, the immersion, heel, and trim are fully coupled, and the equationsare represented using a plane area, a primary moment, and a moment of inertia of the waterplane area. Therefore, it is possible to calculate the additional factor related the water plane areafor estimating stability. Position and orientation of the floating structure are obtained by itera-tive calculation. The calculated results are compared with the previous studies in the aspect tothe performance and the accuracy.Key words:Computational Hydrostatics, Floating Structure, Large Inclination, Nonlinear Hydro-static Force, Static Equilibrium
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Development of a simulation framework and applications to new production processes in shipyards
Computer-aided Design, 2012Co-Authors: Kwang-phil ParkAbstract:Recently, a floating crane is frequently used for the block lifting, transportation, turn-over, and assembly processes in waves. For these production processes, it is important to detect collision in advance between assembly blocks or the block and the other facilities like the wire rope and the barge which are carrying the block. The tension of the wire rope also needs to be calculated to check that the maximum value is less than the safety criteria. In this paper, a mathematical model is constructed based on multibody system dynamics considering the external Forces such as the Hydrostatic, hydrodynamic, wind Force, etc. To observe the dynamic motions of the floating crane and the block, and to calculate the tension of the wire rope, the time and event simulations are performed by solving the mathematical model in the computer. For applying the simulations to the various production processes in shipyards, a simulation framework is developed. The simulation framework consists of a simulation kernel, application-specific modules, a simulation coordinator, development tools, and post-processing tools. The simulation kernel manages both DEVS (discrete event system specification) and DTSS (discrete time system specification) to deal with various simulation requests. The application-specific modules provide the functions used in application systems, such as dynamic analysis, collision detection, visualization, wire rope Force calculation, Hydrostatic Force calculation and hydrodynamic Force calculation. The simulation coordinator manages the data of the simulation kernel and the application-specific modules. The development tools provide a development process, a scenario manager, and a simulation model generator. The post-processing tools are used to report the simulation results. The examples of block lifting, transportation, turn-over, and assembly simulations are developed based on the framework to show that the framework is useful for the simulations of the production processes using one or more floating cranes.
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Dynamic factor analysis considering elastic boom effects in heavy lifting operations
Ocean Engineering, 2011Co-Authors: Kwang-phil ParkAbstract:Abstract The dynamic factor is the ratio of the maximum dynamic load to the static load acting on the wire ropes between the boom of a floating crane and a cargo. In this paper, the dynamic factor is analyzed based on dynamic simulations of a floating crane and a cargo, considering an elastic boom. For the simulation, we designed a multibody system that consists of a floating crane barge, an elastic boom, and a cargo connected to the boom through wire ropes. The dynamic equations of motion of the system are based on flexible multibody system dynamics. Six-degree-of-freedom motions are considered for the floating crane and for the cargo, and three-dimensional deformations for the elastic boom. The Hydrostatic Force, the hydrodynamic Force, the gravitational Force, and the wire rope Forces are considered as external Forces. The dynamic factor is obtained by numerically solving the equation. The effects of the elastic boom on heavy cargo lifting are discussed by comparing the simulation results of an elastic boom and a rigid boom.
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dynamic response of a floating crane in waves by considering the nonlinear effect of Hydrostatic Force
Ship Technology Research, 2010Co-Authors: Kwang-phil ParkAbstract:The dynamic response of a floating crane and a suspended heavy cargo is analyzed. A mathematical model of the 6-degree-of-freedom floating crane and the 6-degree-of-freedom heavy cargo is developed based on multibody system dynamics. The Hydrostatic Forces are calculated as nonlinear. The motions of the floating crane and the cargo in waves are calculated and the tension of the wire rope between the two is compared with the measured data
Alexander V Neimark - One of the best experts on this subject based on the ideXlab platform.
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Polymer Translocation through a Nanopore: DPD Study
Journal of Physical Chemistry B, 2013Co-Authors: Kan Yang, Aleksey Vishnyakov, Alexander V NeimarkAbstract:Translocation of a polymer chain through a narrow pore is explored using 3D explicit solvent dissipative particle dynamics simulation. We study the dependence of the translocation dynamics and translocation time τ on the chain length N, driving Force magnitude E, and solvent quality. Two types of driving Forces are considered: uniform Hydrostatic Force, which is applied equally to the chain and solvent particles, and uniform electrostatic Force, which is applied selectively to the charged particles in the chain and oppositely charged counterions in the solvent. We concluded that the scaling correlations τ ∼ E–ξ and τ ∼ Nβ are valid only for coil-like chains. For globular chains, the exponents ξ and β could not be identified with a reasonable accuracy. While the found value of ξ agrees with published experimental results and does not depend on the driving Force type, the exponent β depends on the driving Force and solvent quality. This is explained by nonequilibrium effects, as in the systems considered, t...
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Polymer translocation through a nanopore: DPD study
Journal of Physical Chemistry B, 2013Co-Authors: Kan Yang, Aleksey Vishnyakov, Alexander V NeimarkAbstract:Translocation of a polymer chain through a narrow pore is explored using 3D explicit solvent dissipative particle dynamics simulation. We study the dependence of the translocation dynamics and translocation time τ on the chain length N, driving Force magnitude E, and solvent quality. Two types of driving Forces are considered: uniform Hydrostatic Force, which is applied equally to the chain and solvent particles, and uniform electrostatic Force, which is applied selectively to the charged particles in the chain and oppositely charged counterions in the solvent. We concluded that the scaling correlations τ ~ E(-ξ) and τ ~ N(β) are valid only for coil-like chains. For globular chains, the exponents ξ and β could not be identified with a reasonable accuracy. While the found value of ξ agrees with published experimental results and does not depend on the driving Force type, the exponent β depends on the driving Force and solvent quality. This is explained by nonequilibrium effects, as in the systems considered, the time of translocation is comparable with the time of chain relaxation. These effects, manifested in the changes of chain conformation in the process of translocation, were analyzed on the basis of the variation of the gyration radii of cis and trans segments of the chain in normal and lateral directions. A prominent chain expansion was observed for coils and was insignificant for globules. This work demonstrates the feasibility of the 3D dissipative particle dynamics modeling of translocation phenomena and accounting for the electrostatic interactions with explicit counterions, as well as for the solvent quality, in a computationally efficient manner.
Kan Yang - One of the best experts on this subject based on the ideXlab platform.
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Polymer Translocation through a Nanopore: DPD Study
Journal of Physical Chemistry B, 2013Co-Authors: Kan Yang, Aleksey Vishnyakov, Alexander V NeimarkAbstract:Translocation of a polymer chain through a narrow pore is explored using 3D explicit solvent dissipative particle dynamics simulation. We study the dependence of the translocation dynamics and translocation time τ on the chain length N, driving Force magnitude E, and solvent quality. Two types of driving Forces are considered: uniform Hydrostatic Force, which is applied equally to the chain and solvent particles, and uniform electrostatic Force, which is applied selectively to the charged particles in the chain and oppositely charged counterions in the solvent. We concluded that the scaling correlations τ ∼ E–ξ and τ ∼ Nβ are valid only for coil-like chains. For globular chains, the exponents ξ and β could not be identified with a reasonable accuracy. While the found value of ξ agrees with published experimental results and does not depend on the driving Force type, the exponent β depends on the driving Force and solvent quality. This is explained by nonequilibrium effects, as in the systems considered, t...
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Polymer translocation through a nanopore: DPD study
Journal of Physical Chemistry B, 2013Co-Authors: Kan Yang, Aleksey Vishnyakov, Alexander V NeimarkAbstract:Translocation of a polymer chain through a narrow pore is explored using 3D explicit solvent dissipative particle dynamics simulation. We study the dependence of the translocation dynamics and translocation time τ on the chain length N, driving Force magnitude E, and solvent quality. Two types of driving Forces are considered: uniform Hydrostatic Force, which is applied equally to the chain and solvent particles, and uniform electrostatic Force, which is applied selectively to the charged particles in the chain and oppositely charged counterions in the solvent. We concluded that the scaling correlations τ ~ E(-ξ) and τ ~ N(β) are valid only for coil-like chains. For globular chains, the exponents ξ and β could not be identified with a reasonable accuracy. While the found value of ξ agrees with published experimental results and does not depend on the driving Force type, the exponent β depends on the driving Force and solvent quality. This is explained by nonequilibrium effects, as in the systems considered, the time of translocation is comparable with the time of chain relaxation. These effects, manifested in the changes of chain conformation in the process of translocation, were analyzed on the basis of the variation of the gyration radii of cis and trans segments of the chain in normal and lateral directions. A prominent chain expansion was observed for coils and was insignificant for globules. This work demonstrates the feasibility of the 3D dissipative particle dynamics modeling of translocation phenomena and accounting for the electrostatic interactions with explicit counterions, as well as for the solvent quality, in a computationally efficient manner.
Namkug Ku - One of the best experts on this subject based on the ideXlab platform.
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The flexible multibody dynamics of a floating offshore wind turbine in marine operations
Ships and Offshore Structures, 2016Co-Authors: Kwang-phil Park, Namkug KuAbstract:ABSTRACTIn this paper, a dynamic response analysis of a floating offshore wind turbine is performed during the rotor rotation under wind and wave loads after the turbine was installed on a floating platform.The floating offshore wind turbine is modelled as a system that consists of the floating platform, a tower, a nacelle, a hub, and three blades. Flexible multibody dynamics is employed in constructing the equations dealing with motion for the floating offshore wind turbine in the dynamic response analysis. The tower and the blades are constructed as flexible bodies by using the three-dimensional beam element. The external Forces acting on the floating platform included the Hydrostatic Force, the hydrodynamic Force, and the mooring Force. Then, aerodynamic Force was calculated based on the blade element momentum theory, and was applied to the blades.Using the wave and wind conditions that are generally required to operate a 5-MW offshore wind turbine, a numerical simulation was performed to determine the...
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computation of nonlinear Hydrostatic Force and position of a floating structure considering the coupled large inclined angles
Korean Journal of Computational Design and Engineering, 2016Co-Authors: Namkug Ku, Kwang-phil ParkAbstract:Received 21 December 2015; received in revised form 19 January 2016; accepted 20 January 2016ABSTRACTWhen ships and offshore plants are flooded or the floating crane is equipped with a heavyobject, these floating structures are excessively inclined. In this case, immersion, heel, and trimaffecting the Hydrostatic restoration performance are very large and are coupled each other. Inthis paper, in order to calculate a static equilibrium position of floating structures with exces-sive inclination, the nonlinear governing equations were constructed by sequential linearization.In the governing equation, the immersion, heel, and trim are fully coupled, and the equationsare represented using a plane area, a primary moment, and a moment of inertia of the waterplane area. Therefore, it is possible to calculate the additional factor related the water plane areafor estimating stability. Position and orientation of the floating structure are obtained by itera-tive calculation. The calculated results are compared with the previous studies in the aspect tothe performance and the accuracy.Key words:Computational Hydrostatics, Floating Structure, Large Inclination, Nonlinear Hydro-static Force, Static Equilibrium
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Dynamic Constrained Force of Tower Top and Rotor Shaft of Floating Wind Turbine
Journal of the Computational Structural Engineering Institute of Korea, 2012Co-Authors: Namkug KuAbstract:In this study, we calculate dynamic constrained Force of tower top and blade root of a floating offshore wind turbine. The floating offshore wind turbine is multibody system which consists of a floating platform, a tower, a nacelle, and a hub and three blades. All of these parts are regarded as a rigid body with six degree-of-freedom(DOF). The platform and the tower are connected with fixed joint, and the tower, the nacelle, and the hub are successively connected with revolute joint. The hub and three blades are connected with fixed joint. The recursive formulation is adopted for constructing the equations of motion for the floating wind turbine. The non-linear Hydrostatic Force, the linear hydrodynamic Force, the aerodynamic Force, the mooring Force, and gravitational Forces are considered as external Forces. The dynamic load at the tower top, rotor shaft, and blade root of the floating wind turbine are simulated in time domain by solving the equations of motion numerically. From the simulation results, the mutual effects of the dynamic response between the each part of the floating wind turbine are discussed and can be used as input data for the structural analysis of the floating offshore wind turbine.
El J Hajalicia - One of the best experts on this subject based on the ideXlab platform.
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evaluation of the growth environment of a Hydrostatic Force bioreactor for preconditioning of tissue engineered constructs
Tissue Engineering Part C-methods, 2015Co-Authors: H L Leonardkatherine, R Henstockjames, P Whiteleyjonathan, M Osbornejames, L Waterssarah, El J HajaliciaAbstract:Bioreactors have been widely acknowledged as valuable tools to provide a growth environment for engineering tissues and to investigate the effect of physical Forces on cells and cell-scaffold constructs. However, evaluation of the bioreactor environment during culture is critical to defining outcomes. In this study, the performance of a Hydrostatic Force bioreactor was examined by experimental measurements of changes in dissolved oxygen (O2), carbon dioxide (CO2), and pH after mechanical stimulation and the determination of physical Forces (pressure and stress) in the bioreactor through mathematical modeling and numerical simulation. To determine the effect of Hydrostatic pressure on bone formation, chick femur skeletal cell-seeded hydrogels were subjected to cyclic Hydrostatic pressure at 0–270 kPa and 1 Hz for 1 h daily (5 days per week) over a period of 14 days. At the start of mechanical stimulation, dissolved O2 and CO2 in the medium increased and the pH of the medium decreased, but remained within h...
