• Proceedings of the Acoustical Society of Korea Conference
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• 1996.06a
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• pp.9-12
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• 1996

This paper introduces an analysis of the non-axisymmetric mode due to in-plane vibration of an annular type piezoelectric actuator using FEM(Finite Element Method). The actuator is used as stator of ultrasonec motor. The freqrency charecterisrics and non-axisymmetric mode of the annular piezoelectric acruator are considered at a steady-state condition. The non-axisymmetric mode is occured by two sinusodial voltage sources with $\pi$/2 phase difference on the time domain. The resonant frequency of non-axisymmetric of non-axisymmetric mode is 60.358 kHz and 59.880 kHz for calculation and measurement, respectivly. The error was 0.8% between calculation and measurement. The revolution of the non-axisymmetric mode for actuator is analized at a period of exciting voltage sources using annimation. It is confirmed that the actuator has an usefulness as the stator of ultrasonic motor and the preposed method has a properity.

• Journal of ILASS-Korea
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• v.23 no.1
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• pp.16-21
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• 2018

The current study has developed an in-house 3D FEM code in order to model thermoacoustic problems in a gas turbine combustion system and compared calculation results of main instability characteristics with measured ones from a lab-scale partially-premixed combustor. From the comparison of calculation results with the measured data, the current model could successfully capture the harmonic longitudinal instability frequencies and their spatial distributions of the acoustic field as well as the growth rate of self-excited modes.

• Structural Engineering and Mechanics
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• v.57 no.2
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• pp.221-238
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• 2016

One of the objectives of this study is to implement the direct calculation of the torsional moment of inertia for non-circular cross-sections, which is based on the St. Venant torsion formulation and the finite element method. Recently the proposed method provides a unique calculation of the torsional rigidity of simply and multiply connected cross-sections. Next, free vibration analyses of cylindrical and non-cylindrical helices with non-circular cross-sections are solved by a curved two-nodded mixed finite element based on the Timoshenko beam theory. Some thin-thick closed or open sections are handled and the natural frequencies of cylindrical and non-cylindrical helices are compared with the literature and the commercial finite element program SAP2000.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.948-950
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• 2005

This paper compared the test data with the loss when a conductor is exposed to the magnetic fieldof reactors after generating external magnetic field in specimen by means of an air core reactor model and the calculation of loss came from a tying the combination of FEM and integral method. It was applied to the loss measurement of transformers due to leakage flux.

• Journal of KSNVE
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• v.9 no.2
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• pp.310-316
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• 1999

4-Pole parameter method based on an acoustic theory is very popular for the analysis of the acoustic behavior of the car exhaust system. However, this method is applicable only for the simple shape of acoustic elements of the muffler. Numerical methods such as FEM(Finite Element Method) or BEM(Boundary Element Method) can also provide acceptable results for the acoustic analysis of the car exhaust system. Even though these numerical methods have benefits for the analysis of complicated shape of acoustic elements of the muffler, time consuming is another problem during modeling and numerical calculation. Combining benefits of both methods, the new code called the hybrid method for car exhaust system is introduced. And the developed code is utilized for calculation of the transmission loss of a main muffler of an automobile comparing with the experimental results.

• Progress in Superconductivity and Cryogenics
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• v.12 no.2
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• pp.13-16
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• 2010

The superconducting synchronous motor or generator mostly has high permeability iron only around outer yoke portion. Therefore, if excitation voltage (Back E.M.F) is calculated from 2 dimensional magnetic field distributions, it can be largely different from actual value due to additional voltage originated from end coils. In order to calculate the excitation voltage more accurately, 3 dimensional magnetic field calculation is necessary for including the end coil effect from large air-gap structure. The excitation voltage can be calculated by stator (armature) coil linkage flux originated from rotor (field) coil excitation, but it is difficult to calculate the flux linkage exactly because of complicated structure of the stator coil. This paper shows a method to calculate the excitation voltage from 3 dimensional magnetic energy that can be calculated directly from volume integration of magnetic flux density and field intensity scalar product through FEM (Finite Element Method) analysis software.

• Journal of Electrical Engineering and Technology
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• v.6 no.2
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• pp.208-214
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• 2011

In this paper, a characteristics analysis and calculation of the suspending force of a novel bearingless switched reluctance motor (BLSRM) with hybrid stator poles is proposed. The operating principle and permeance are calculated to find an appropriate control scheme for a proposed motor. Furthermore, a mathematical model for suspending force is derived. Finite element analysis is also employed to compare with the expressions for suspending force. Finally, the validity of the structure and the mathematical model is verified by simulation results.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 1999.02a
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• pp.85-88
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• 1999

The study of HTS bulk in permanent magnet applications requires the calculation of forces acting on the bulk. Currents distribution in HTS Superconducting bulk is very important to determine this forces. We have made computer program to find this current distribution and this program is applied to some simple disc-shape HTS bulk being magnetised in a uniform field. The techniques for determination of currents are FEM analysis and iteration method.

• 한국전산유체공학회:학술대회논문집
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• 2003.10a
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• pp.131-133
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• 2003

The streamfunction-vorticity equations for two-dimentional cavity flow are solved by a new finite element method which uses finite spectral basis functions as interpolation functions for rectangular elements. Results for several cases with different Renold's number are compared with benchmark solutions and found to be in well agreement.

• Proceedings of the KSR Conference
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• 2001.10a
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• pp.267-272
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• 2001

A FEM-based analytical approach was used to evaluate the static strength and the fatigue strength of a KHST bogie including eddy current brake system. Calculation was carried out in the fields of linearity and small deformation. The yield strengths were used as criteria for evaluating the static strength and the fatigue limits were used as criteria for evaluating the fatigue strength. The analysis results show that there is not any location that exceeds the allowable criteria.