• Journal of KSNVE
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• v.9 no.4
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• pp.778-784
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• 1999

A method for obtaining the motion of an impact system whose primary and secondary system are composed of lumped masses, springs and dampers, and all the contacts are made through spring and damping elements is presented. The frequency response functions derived from the equations of motion and the impulse response functions obtained from the inverse Fourier transform of the derived frequency response functions are used for the calculation of the system responses. The procedure developed for the calculation of displacements and force time-histories was based on the convolution integrals of impulse response functions and forces applied to the systems. Time histories of displacements and contact forces are obtained for the case where a random excitation is applied to a point in the system. Impact statistics such as contact forces and the time between impacts calculated from those time histories is presented.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.12B no.1
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• pp.13-18
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• 2002

Novel method to calculate flux linkage for 3-D finite element analysis is proposed. It does not require any integral path if the current direction in a coil is known. The flux linkage can be calculated very easily using simple volume based integration. The current direction is calculated based on the recently developed technique by the authors. The novel method for flux linkage calculation is verified by applying to a very complicated deflection yoke coil. The simulation result is compared to the experimental one. From the simulation, it is shown that the proposed method is very accurate and effective to calculate the flux linkage of a coil.

• Communications for Statistical Applications and Methods
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• v.27 no.3
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• pp.377-383
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• 2020

The likelihood-based inference in a nonlinear generalized mixed model often requires computing moments of truncated multivariate normal random variables. Many methods have been proposed for the computation using a recurrence relation or the moment generating function; however, these methods rely on high dimensional numerical integrations. The numerical method is known to be inefficient for high dimensional integral in accuracy. Besides the accuracy, the methods demand too much computing time to use them in practical analyses. In this note, a moment calculation method is proposed under an assumption of a certain covariance structure that occurred mostly in generalized mixed models. The method needs only low dimensional numerical integrations.

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.280-285
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• 2001

As an integral part of the probabilistic fracture mechanics analysis, stress intensity factor calculation scheme for semi-elliptical surface flaws in thin-walled cylinder has been introduced. The approximation solution utilizes the influence coefficients to calculate the stress intensity factor at the crack tip. This method has been compared with other solution methods including 3-D finite element analysis for cooldown boundary condition. The analysis results confirmed that the simplified methods provided sufficiently accurate stress intensity factor values for axial semi-elliptcal flaws on the surface of the reactor pressure vessel.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.7 s.178
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• pp.1795-1800
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• 2000

One of the principal sources of vibration and noise in permanent magnetic machines is cogging torque, which is induced by interaction between the rotor poles and the stator teeth. For its analysis, using finite element analysis is very time consuming and the calculation of performance factors is extremely sensitive to the discretization. Especially, Maxwell stress tensor method is sensitive to the location of integral path. In this paper, a cogging permeance fuction is defined and replaced by the straight line. And it is assumed that the flux density acting on the stator's tooth side is the euqal to the flux density of the slot area. Using this definition and assumption, analytical calculation of cogging torque is presented and validated. And several reduction method is introduced.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.12
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• pp.1872-1876
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• 2012

A calculation method of the breakdown voltage for the drain region with the cylindrical structure in LDMOS is proposed. The depletion region of the drain is divided into many smaller regions and the doping concentration of each split region is assumed to be uniformly distributed. The field and potential in each split region is calculated by the integration of the Poisson equation and the ionization integral method is used to compute the breakdown voltage. The breakdown voltage resulted from the proposed method shows the maximum relative error of 2.2% compared with the result of the 2-dimensional device simulation using BANDIS.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.31 no.12
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• pp.173-179
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• 1982

This paper presents a modified quasi-static approximate solution derived from the Maxwell's equations of integral form for the calculation of magnetic shielding effectiveness in a non-uniform enclosure such as metal-clad high-voltage test laboratory. It also describes the simplified relationship between the electrical parameters applicable to the engineering calculations of electromagnetic absorption loss which comprise the resultant effects due to the welding seams and short-circuited slots as well as the shielding material properties. A numerical example shows the fairly good agreements with experimental results measured on the absorption loss vs. incident wave frequency without any unreasonable rapid increase.

• 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.

• Proceedings of the Korea Concrete Institute Conference
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• 1992.10a
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• pp.240-244
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• 1992

The values of a linguistic variable are words, phrases, or sentences in a given language. For example, structural damage can be considered as linguistic variable with values such a 'severely damaged', 'moderately damaged', which are meaningful classifications but not clearly defined, This paper is to evaluate reasonably the correction factor of bridge capacity with the aid of fuzzy sets theory. By using the above mentioned fuzzy measure, the concept of fuzzy integral and linear membership function can be defined. It is concluded that the fuzzy sets theory cam be applied to determine reasonably the correction factor of bridge capacity.

• Proceedings of the KIEE Conference
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• 2008.10a
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• pp.111-112
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• 2008

Induced electromagnetic fields of printed circuit board are computed using method of moment. In this calculation PEC and dielectric boards are considered when exposed to the external fields. The volume and surface integral equations are presented for the electromagnetic wave scattering from plate structures composed of dielectric and conducting objects. To reduce the computing time a fast multipole technique is applied.