• Journal of the Society of Naval Architects of Korea
• /
• v.43 no.6 s.150
• /
• pp.631-637
• /
• 2006

This paper presents a numerical method to solve the ship motion coupled with internal fluid flow. Physically the internal fluid motion is coupled with the ship motion. Hitherto the previous numerical results of the coupled motion predict only the general tendency with experiments. The main reason of inaccuracy is that the coupled dynamics of ship motion and internal water motion is not accurately accounted. In this study CFD technique based on VOF is employed for the accurate analysis of flooding water motion. Some cases of the 24th ITTC stability committee's benchmark.study for tanker with internal fluid are analyzed by coupling the ship motion and sloshing dynamics. The calculated ship motion is compared with the experimental result to validate the coupled scheme and is in agreement with the experimental result.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.27 no.4
• /
• pp.348-355
• /
• 2022

A bipolar DC distribution system suffers from an imbalance in voltages when asymmetric loads are connected at the outputs. Dedicated voltage balancers are required to address the imbalance in bipolar voltage levels. However, additional components eventually increase the cost and decrease the efficiency and power density of the system. Therefore, to deal with the imbalance in output voltages without adding any extra components, this study presents a coupled inductor-based voltage balancing technique with a dual-output CLL resonant converter. The proposed coupled inductor does not require extra magnetic components to balance the output voltages because it is the result of resonant inductors of the CLL tank circuit. It can also avoid complex control schemes applied to voltage balancing. Moreover, with the proposed coupled inductor, the CLL converter acquires good features including zero voltage and zero current switching. Detailed analysis of the proposed coupled inductor is presented with different load conditions. A 3.6-kW hardware prototype was built and tested to validate the performance of the proposed coupled inductor-based voltage balancing technique.

• Interaction and multiscale mechanics
• /
• v.2 no.4
• /
• pp.397-411
• /
• 2009

The effect of soil-structure interaction on a simple single storeyed and two bay space frame resting on a pile group embedded in the cohesive soil (clay) with flexible cap is examined in this paper. For this purpose, a more rational approach is resorted to using the three dimensional finite element analysis with realistic assumptions. The members of the superstructure and substructure are descretized using 20 node isoparametric continuum elements while the interface between the soil and pile is modeled using 16 node isoparametric interface elements. Owing to viability in terms of computational resources and memory requirement, the approach of uncoupled analysis is generally preferred to coupled analysis of the system. However, an interactive analysis of the system is presented in this paper where the building frame and pile foundation are considered as a single compatible unit. This study is focused on the interaction between the pile cap and underlying soil. In the parametric study conducted using the coupled analysis, the effect of pile spacing in a pile group and configuration of the pile group is evaluated on the response of superstructure. The responses of the superstructure considered include the displacement at top of the frame and moments in the superstructure columns. The effect of soil-structure interaction is found to be quite significant for the type of foundation used in the study. The percentage variation in the values of displacement obtained using the coupled and uncoupled analysis is found in the range of 4-17 and that for the moment in the range of 3-10. A reasonable agreement is observed in the results obtained using either approach.

• Coupled systems mechanics
• /
• v.9 no.2
• /
• pp.163-182
• /
• 2020

Coupled thermo-mechanical analysis of reinforced concrete slab at elevated temperatures from a fire accounting for nonlinear thermal parameters is carried out. The main focus of the paper is put on a one-way continuous reinforced concrete slab exposed to fire from the single (bottom) side as the most typical working condition under fire loading. Although contemporary techniques alongside the fire protection measures are in constant development, in most cases it is not possible to avoid the material deterioration particularly nearby the exposed surface from a fire. Thereby the structural fire resistance of reinforced concrete slabs is mostly influenced by a relative distance between reinforcement and the exposed surface. A parametric study with variable concrete cover ranging from 15 mm to 35 mm is performed. As the first part of a one-way coupled thermo-mechanical analysis, transient nonlinear heat transfer analysis is performed by applying the net heat flux on the exposed surface. The solution of proposed heat analysis is obtained at certain time steps of interest by α-method using the explicit Euler time-integration scheme. Spatial discretization is done by the finite element method using a 1D 2-noded truss element with the temperature nodal values as unknowns. The obtained results in terms of temperature field inside the element are compared with available numerical and experimental results. A high level of agreement can be observed, implying the proposed model capable of describing the temperature field during a fire. Accompanying thermal analysis, mechanical analysis is performed in two ways. Firstly, using the guidelines given in Eurocode 2 - Part 1-2 resulting in the fire resistance rating for the aforementioned concrete cover values. The second way is a fully numerical coupled analysis carried out in general-purpose finite element software DIANA FEA. Both approaches indicate structural fire behavior similar to those observed in large-scale fire tests.

• Geomechanics and Engineering
• /
• v.10 no.4
• /
• pp.423-436
• /
• 2016

Currently, there is a great interest in the coupling between multiphase fluid flow and geomechanical effects in hydrocarbon reservoirs and surrounding rocks. The ideal solution for this coupled problem is to introduce the geomechanical effects through the stress analysis solution and implement an algorithm, which assures that the equations governing the flow and stress analyses are obeyed in each time step. This paper deals with the implementation of a program (FORTRAN90 interface code), which was developed to couple conventional reservoir (ECLIPSE) and geomechanical (ABAQUS) simulators, using a partial coupling algorithm. The explicit coupled hydro-mechanical behavior of Iranian field during depletion and $CO_2$ injection is studied using the soils consolidation procedure available in ABAQUS. Time dependent reservoir pressure fields obtained from three dimensional compositional reservoir models were transferred into finite element reservoir geomechanical models in ABAQUS as multi-phase flow in deforming reservoirs cannot be performed within ABAQUS. The FEM analysis of the reservoir showed no sign of plastic strain under production and $CO_2$ injection scenarios in any part of the reservoir and the stress paths do not show a critical behavior.

• Journal of the Korean Institute of Telematics and Electronics T
• /
• v.36T no.1
• /
• pp.79-85
• /
• 1999

The propagation properties of the high speed pulse signal in time domain using the equivalent circuits for the analysis by SPICE on the coupled microstrip lines are investigated. In this paper, the SPICE program is used for the crosstalk analysis on the coupled microstrip lines. The results of crosstalk of coupled microstrip lines compared to one by Branin and FDTD method. And the near-end and far-end crosstalk on coupled lines are analyzed for the square pulse and trapezoidal pulse. The results of this paper are apply To the determination for the geometric structure and the frequency of signal pulse in design of MIC and MMIC by the CAD program.

• Journal of the Korean Chemical Society
• /
• v.29 no.4
• /
• pp.382-389
• /
• 1985

The effect of plasma operational parameters for the determination of rare earth elements(REE) by means of inductively coupled plasma(ICP) spectrometry was investigated. While the increase in the flow rate of carrier gas argon enhanced the sensitivity and lowered the detection limit, significant ionization interferences were observed. The decrease in RF power increased the signal to background ratio. The observation point showing the lowest ionization interference was slightly higher than the position where the spatial profile of the analyte reached the maximum. The detection limits of the spectral lines commonly used for the determination of REE were measured and the spectral lines relatively free from spectral interferences were chosen.

• Structural Engineering and Mechanics
• /
• v.73 no.6
• /
• pp.667-684
• /
• 2020

In this article, the static responses of layered magneto-electro-thermo-elastic (METE) plates in thermal environment have been investigated through FE methods. By using Reddy's third order shear deformation theory (TSDT) in association with the Hamilton's principle, the direct and derived quantities of the coupled system have been obtained. The coupled governing equations of METE plates have been derived through condensation technique. Three layered METE plates composed of piezoelectric and piezomagnetic phases are considered for evaluation. For investigating the correctness and accuracy, the results in this article are validated with previous researches. In addition, a special attention has been paid to evaluate the influence of different electro-magnetic boundary conditions and pyrocoupling on the coupled response of METE plates. Finally, the influence of stacking sequences, magnitude of temperature load and aspect ratio on the coupled static response of METE plates are investigated in detail.

• Ocean Systems Engineering
• /
• v.3 no.4
• /
• pp.295-307
• /
• 2013

More FOWTs (floating offshore wind turbines) will be installed as relevant regulations and technological hurdles are removed in the coming years. In the present study, a numerical prediction tool has been developed for the fully coupled dynamic analysis of FOWTs in time domain including aero-loading, tower elasticity, blade-rotor dynamics and control, mooring dynamics, and platform motions so that the influence of rotor-control dynamics on the hull-mooring performance and vice versa can be assessed. The developed coupled analysis program is applied to Hywind spar design with 5 MW turbine. In case of spar-type floaters, the control strategy significantly influences the hull and mooring dynamics. If one of the control systems fails, the entire dynamic responses of FOWT can be significantly different. Therefore, it is important to maintain various control systems in a good operational condition. In this regard, the effects of failed blade pitch control system on FOWT performance including structural and dynamic responses of blades, tower, and floater are systematically investigated. Through this study, it is seen that the failure of one of the blade pitch control system can induce significant dynamic loadings on the other blades and the entire FOWT system. The developed technology and numerical tool are readily applicable to any types of floating wind farms in any combinations of irregular waves, dynamic winds, and steady currents.

• Proceedings of the KSME Conference
• /
• 2003.04a
• /
• pp.839-844
• /
• 2003

The effect of water level on the free vibration of a partially water-filled two rectangular plates structure was investigated by experimental modal analysis and finite element analysis using ANSYS computer program. Modal parameters of two rectangular plates coupled with water were obtained by means of experiment and the FEM solutions were compared with the experimental solutions to verify the finite element model. As a result, the comparison between the experiment and FEM results showed excellent agreement. The transverse vibration modes, in-phase and out-of-phase, were observed alternately in the fluid-coupled system. The effect of water level and water gap size on the fluid-coupled natural frequency were investigated. It was found that the natural frequency of the partially water-filled two rectangular plates are not proportional to the water level, but depend on mode number of plates.