• The KSFM Journal of Fluid Machinery
• /
• v.17 no.4
• /
• pp.70-75
• /
• 2014

In this paper a analysis method is presented to obtain the steady state dynamic response from the finite element based equations of a rotor-bearing system with initial deflection. The method has been applied to analyze the dynamic response of the two-shaft rotor-bearing system with rigid coupling offset in a heavy duty gas turbine-generator. Bumps in the dynamic response of each rotor system have been observed at each critical speed due to the effect of initial deflection for rigid coupling offset. And, the dynamic responses have been shown to reduce for operating condition changes from cold to hot.

• Proceedings of the KIEE Conference
• /
• 1997.07a
• /
• pp.291-293
• /
• 1997

The external magnetic field which is applied to the superconducting wire generates coupling loss. Analytical method has been used for the calculation of the coupling loss. This paper calculates the coupling loss that is generated in the matrix by the external magnetic field. Two-dimensional Finite Element Method has been used for the calculation.

• Textile Coloration and Finishing
• /
• v.19 no.5
• /
• pp.37-40
• /
• 2007

The electrostatic layer-by-layer technique provides a convenient way to control the construction of ultrathin films at nano-scale ranges and can be easily obtained. It can be also applicable to fiber substrate with dye compounds. We have fabricated multilayer dye films using diazonium resin and three couplers, which are prepared by self-assembly approach. This method is based on layer-by-layer deposition using electrostatic attraction between oppositely charged ions. Beside, the diazo coupling reaction proceeded to form azo dye layer on the PET fibers the same time. The corresponding results of the multilayer films have been discussed on the level of color strength (K/S).

• The Journal of the Korea institute of electronic communication sciences
• /
• v.15 no.6
• /
• pp.1187-1194
• /
• 2020

We presented a method of deep quiz cropping for automatic construction of quiz pool in online quiz systems. The method detects question boxes and sunda boxes in images captured from test papers by a deep learning-based object detector, and makes pairs of question box and sunda box by the box coupling. We applied the deep quiz cropping to images captured from test papers and achieved successful results.

• Journal of Electrical Engineering and Technology
• /
• v.9 no.6
• /
• pp.2049-2057
• /
• 2014

In this paper, a numerical method for analyzing coupling between high-altitude electromagnetic pulse (HEMP) as external field and a shielded twisted pair (STP) cable is proposed, which is based on an expanded chain matrix. Load responses of electromagnetic (EM) field excitation in uniform transmission line (TL) are solved by Baum-Liu-Tesche (BLT) equations in frequency domain, however, it is difficult to apply BLT equations to solve load responses of STP cable because the iteratively changing configuration of each twisted pairs are involved in cable. To avoid this problem and decrease memory and CPU time, we proposed the expanded chain matrix modeling method that is calculated using ABCD parameters, and applied multi-conductor transmission line (MTL) theory to consider the EMP coupling effectiveness of each twisted pairs. The results implemented by the proposed method are presented and compared with those obtained by the finite-difference time domain (FDTD) method as a kind of 3D full wave analysis.

• Wind and Structures
• /
• v.20 no.3
• /
• pp.423-448
• /
• 2015

In this paper the unsteady fluid-structure interaction (FSI) problems with large structural displacement are solved by partitioned solution approaches in the arbitrary Lagrangian-Eulerian finite element framework. The incompressible Navier-Stokes equations are solved by the characteristic-based split (CBS) scheme. Both a rigid body and a geometrically nonlinear solid are considered as the structural models. The latter is solved by Newton-Raphson procedure. The equation governing the structural motion is advanced by Newmark-${\beta}$ method in time. The dynamic mesh is updated by using moving submesh approach that cooperates with the ortho-semi-torsional spring analogy method. A mass source term (MST) is introduced into the CBS scheme to satisfy geometric conservation law. Three partitioned coupling strategies are developed to take FSI into account, involving the explicit, implicit and semi-implicit schemes. The semi-implicit scheme is a mixture of the explicit and implicit coupling schemes due to the fluid projection splitting. In this scheme MST is renewed for interfacial elements. Fixed-point algorithm with Aitken's ${\Delta}^2$ method is carried out to couple different solvers within the implicit and semi-implicit schemes. Flow-induced vibrations of a bridge deck and a flexible cantilever behind an obstacle are analyzed to test the performance of the proposed methods. The overall numerical results agree well with the existing data, demonstrating the validity and applicability of the present approaches.

• Coupled systems mechanics
• /
• v.8 no.5
• /
• pp.393-414
• /
• 2019

This paper presents seismic analysis of concrete gravity dams considering soil-structure-fluid interaction. Displacement based plane strain finite element formulation is considered for the dam and foundation domain whereas pressure based finite element formulation is considered for the reservoir domain. A direct coupling method has been adopted to obtain the interaction effects among the dam, foundation and reservoir domain to obtain the dynamic responses of the dam. An efficient absorbing boundary condition has been implemented at the truncation surfaces of the foundation and reservoir domains. A parametric study has been carried out considering each domain separately and collectively based on natural frequencies, crest displacement and stress at the neck level of the dam body. The combined frequency of the entire coupled system is very less than that of the each individual sub-system. The crest displacement and neck level stresses of the dam shows prominent enhancement when coupling effect is taken into consideration. These outcomes suggest that a complete coupled analysis is necessary to obtain the actual responses of the concrete gravity dam. The developed methodology can easily be implemented in finite element code for analyzing the coupled problem to obtain the desired responses of the individual subdomains.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.23 no.9
• /
• pp.1073-1078
• /
• 2012

This paper presented the extraction solution for the coupling coefficient at the magnetically coupled wireless power transmission(WPT) system through the analysis of its equivalent circuit considering the loss. The conventional extraction solution using coupled mode theory is generalized employing the extracted solution considering the load resistance. Consequently, the measuring process of extracting coupling coefficient becomes convenient since the even/odd mode analysis is not necessary. Furthermore, the coupling coefficient obtained from the induced extraction method was in excellent agreement with the coupling coefficient obtained using the ratio of magnetic flux passing through the two loops. The extraction of the accurate coupling coefficient at the magnetically coupled WPT is an essential work to analyze and optimize the WPT system.

• Earthquakes and Structures
• /
• v.7 no.5
• /
• pp.817-842
• /
• 2014

ASCE/SEI 41-13 provides modeling parameters and numerical acceptance criteria for various types of members that are useful for evaluating the seismic performance of reinforced concrete (RC) building structures. To accurately evaluate the global performance of a coupled wall system, it is crucial to first properly define the component behaviors (i.e., force-displacement relationships of shear walls and coupling beams). However, only a few studies have investigated on the modeling of RC coupling beams subjected to earthquake loading to date. The main objective of this study is to assess the reliability of ASCE 41-13 modeling parameters specified for RC coupling beams with various design details, based on a database compiling almost all coupling beam tests available worldwide. Several recently developed coupling beam models are also reviewed. Finally, a rational method is proposed for determining the chord yield rotation of RC coupling beams.

• 한국전산유체공학회:학술대회논문집
• /
• 2005.10a
• /
• pp.111-116
• /
• 2005

Two coupling methods for the Navier-Stokes equations and a two-equation turbulence model equations are compared. They are the strongly coupled method and the loosely coupled method. The strongly coupled method solves the Navier-Stokes equations and the two-equation turbulence model equations simultaneously, while the loosely coupled method solves the Navier-Stokes equation with the turbulence viscosity fixed and subsequently solves the turbulence model equations with all the flow quantities fixed. In this paper, performances of two coupling methods are compared for two and three-dimensional problems.