• Architectural research
• /
• v.9 no.1
• /
• pp.39-45
• /
• 2007

The static behavior of continuous system is described by the elastic curve method or is approximately analyzed by a finite element method to be modeled as a discrete system. If a continuous system is constrained by linear constraints which restrict its static behavior, its behavior can be approximately described by the finite element method. It is not easy to describe the constrained behavior by continuous coordinate system. Starting from the generalized inverse method provided by Eun, Lee and Chung, this study is to expand the equation to the continuous systems, to perform the structural analysis of the beam under a uniform loading with interior spring supports, and to investigate the validity of the proposed method through applications.

• Proceedings of the Acoustical Society of Korea Conference
• /
• autumn
• /
• pp.237-242
• /
• 1999

In this study, a design method using plane actuator is developed to make new speaker system, whose shape is much thinner than that of conventional loudspeaker. Piezofilm(PVDF) is used as plane actuator of flat speaker. To avoid the distortion of sound radiated from flat speaker, the frequency response of radiated sound to be flat is taken as the design objective. The electrode pattern and orientation angle of piezofilm actuator is optimized to satisfy the design objective. The formulation is based on the coupled finite element and boundary element method. Genetic algorithm is used in the optimization process, which is useful in the optimization of discrete design variables. Frequency response with optimized piezofilm actuator is made flat enough to satisfy the design objective. For the enhancement of sound power, double-layered piezofilm actuators are also considered. The sound power with double-layered actuator becomes larger than that with single-layered actuator as expected.

• Journal of Magnetics
• /
• v.21 no.3
• /
• pp.393-398
• /
• 2016

This paper proposes a novel 16/10 segmented rotor switched reluctance motor (SSRM) for belt-driven starter generators (BSGs). Different from conventional SRMs, the stator of the proposed SSRM consists of two types of stator poles, i.e., exciting and auxiliary poles, and the rotor is constructed from a series of discrete segments. The topology and operation principle of this proposed SSRM are illustrated firstly, and then the design rules are listed. In addition, the finite element method (FEM) is employed to get the static and dynamic characteristics of the proposed SSRM. Finally, the simulation results are presented to show the validity of the proposed SSRM for BSGs.

• Journal of Advanced Marine Engineering and Technology
• /
• v.10 no.4
• /
• pp.31-40
• /
• 1986

With the tendency toward high speed and high pressure in centrifugal pumps, the problem of sub-synchronous vibration has arisen, caused by the hydraulic forces of the working fluid, such as wearring, balance piston, impeller, etc.. These forces can drastically alter the rotor critical speeds and stability characteristics, and can be acted significant destabilizing forces. For preventing such self-excited vibration, the desing of the rotor system needs, which would secure the stability of the machine. In this paper, a procedure is presented for dynamic modeling of rotor-bearing-seal-impeller systems which consist of rigid disks, distributed parameter finite rotor elements and discrete bearings, seals and impellers. A finite element model including the effects of rotatory inertia and gyroscopic moments is developed using the consistent matrix approach. The technique of dynamic matrix reduction is applied to the shaft matrices to reduce them to a set of matrices of dynamic of significantly fewer degrees of freedom. The representation of bearing, seal and impeller elements is in term of linearized stiffness and damping matrices by reasonably small perturbations from equilibrium. The stability behavior of a typical double suction centrifugal pump is presented. Results show the influence of clearance and flow conditions on running speeds and stability characteristics.

• Tunnel and Underground Space
• /
• v.3 no.1
• /
• pp.96-107
• /
• 1993

This paper deals with the analysis of rock slope stability using the distinct element method. This method consists in analysis of the interaction of discrete block assemblage delimited by elementary joints, which permits to consider the heterogeneous, anisotropic and discontinuous features of the rock mass. In particular, we were able to show that this method, and especially the BRIG3D software, is an outstanding tool which gives informations of greatest interest in order to analyze the toppling mechanisms. We have confirmed the fundamental role of the rock mass structure with different simulations. In the case of toppling phenomena, the essential parameter is the dip of major discontinuities. It has an influence on the intensity and volume of deformations. The anisotropic and heterogeneous features of the rock mass play also an important role. It is proved by insertion of thick rock bars in the structure or varying rock block sizes in the mass. These models modified considerably the stress distribution and the deformation distribution. Finally, we have analyzed the influence of mechanical parameters such as friction angle and tangential stiffness.

• Interaction and multiscale mechanics
• /
• v.1 no.1
• /
• pp.83-101
• /
• 2008

A derivation is given of two-scale models that are able to describe deformation and flow in a fluid-saturated and progressively fracturing porous medium. From the micromechanics of the flow in the cavity, identities are derived that couple the local momentum and the mass balances to the governing equations for a fluid-saturated porous medium, which are assumed to hold on the macroscopic scale. By exploiting the partition-of-unity property of the finite element shape functions, the position and direction of the fractures are independent from the underlying discretization. The finite element equations are derived for this two-scale approach and integrated over time. The resulting discrete equations are nonlinear due to the cohesive crack model and the nonlinearity of the coupling terms. A consistent linearization is given for use within a Newton-Raphson iterative procedure. Finally, examples are given to show the versatility and the efficiency of the approach.

• Earthquakes and Structures
• /
• v.14 no.4
• /
• pp.297-303
• /
• 2018

Seismic behavior of Osmanli and Senyuva stone bridges was addressed in this study. A combination of FEM and DEM was employed for getting closer to the real behavior of the bridge. One of the unique features of this combinational method is simulation close to reality. Modal numerical analysis was also used to verify the modeling. At the end of earthquake, a part of two lateral walls of Osmanli bridge was broken. The growth of arch cracks also increased during the earthquake. A part of right-hand wall of Senyuva Bridge was destructed during the earthquake. The left-hand side of the bridge wall was damaged during the earthquake but was not destructed.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 1999.11a
• /
• pp.124-129
• /
• 1999

In this study, a design method for the flat sound radiator is developed to make new sound radiator system, whose shape is much thinner than that of conventional loudspeaker. Piezofilm (PVDF) is used as actuators of flat sound radiator. To avoid the distortion of sound radiated from flat sound radiator, the frequency response of radiated sound to be flat is taken as the design objective. The electrode pattern and orientation angle of piezofilm actuator is optimized to satisfy the design objective. The formulation is based on the coupled finite element and boundary element method. Genetic algorithm is used in the optimization process, which is useful in the optimization of discrete design variables. Frequency response with optimized piezofilm actuator is made flat enough to satify the design objective. For the enhancement of sound power, double-layered piezofilm actuators are also considered. The sound power with double-layered actuator becomes larger than that with single-layered actuator as expected.

• Animal cells and systems
• /
• v.3 no.4
• /
• pp.413-415
• /
• 1999

Our previous report demonstrated that the rhp51$^＋$, a recA and RAD51 homolog of the fission yeast, encodes three transcripts of 1.9, 1.6 and 1.3 kb which have at least six polyadenylation sites. The 3'-end of the gene alone can direct the formation of multiple, discrete 3'ends of the transcripts. To identify the regulatory element required for the 3'-end formation of -rhp51$^＋$ deletion mapping analysis was performed. Northern blot analysis revealed that the 254-bp DNA fragment including 4 distinct poly (A) sites downstream from the Hindlll site, is crucial for normal 3'-end formation. Deletion of the 3'-terminal AU rich region caused appearance of read-through RNA, leading to enhancement of survival rate of the rhp51 deletion mutant in response to DNA damaging agent, methylmethane sulfonate (MMS). The results imply that the rhp51$^＋$ system may be useful for molecular analysis of the 3'-end formation of RNA in the fission yeast.

• Journal of Power System Engineering
• /
• v.5 no.4
• /
• pp.53-60
• /
• 2001

This paper considers a modeling for the MIMO magnetic bearing system. The rotor is flexible and has a complex shape. To obtain the nominal plant transfer functions, we perform a numerical analysis by using the finite element method(F.E.M.) for the rotor's dynamics, and make a nominal model by reducing the modes from the results. And, we have experimented on the frequency response by a closed-loop identification method, and compared it with the simulation's result on the closed-loop control system.