• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 A
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• pp.64-66
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• 1998

This paper presents a new efficient method for transient analysis in magnetodynamic systems of linear eddy current problems. This mehtod employs the Fourier transform and the high-order frequency sensitivity of harmonic finite element method. By taking into account the time-constant of magnetodynamic system, the Fourier integral of continuous frequency is converted into the Fourier series of discrete frequency. And with the results of Fourier series expansion of converted input wave form, the responses of each sinusoids is superposed to give the total response of the magnetodynamic systems. But, if the frequency band of input wave form is broad, it takes long computational time since all responses for each sinusoids must be calculated. Therefore, the high-order frequency sensitivity method is employed to estimate the response variation to frequency. The proposed algorithm is applied to an induction heating system to validate its numerical efficiency.

• Structural Engineering and Mechanics
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• 제32권2호
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• pp.235-249
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• 2009

The response of concrete structures subjected to shock and blast load involves a rapid transient phase, during which material breach may take place. Such an effect could play a crucial role in determining the residual state of the structure and the possible dispersion of the fragments. Modelling of the transient phase response poses various challenges due to the complexities arising from the dynamic behaviour of the materials and the numerical difficulties associated with the evolving material discontinuity and large deformations. Typical modelling approaches include the traditional finite element method in conjunction with an element removal scheme, various meshfree methods such as the SPH, and the mesoscale model. This paper is intended to provide an overview of several alternative approaches and discuss their respective applicability. Representative concrete material models for high pressure and high rate applications are also commented. Several recent application studies are introduced to illustrate the pros and cons of different modelling options.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.714-714
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• 2005

This paper presents the modeling and impact analysis for a rotating cantilever beam having a concentrated mass. The concentrated mass takes an impact force during the rotating motion and the transient response of the beam induced by the impact is calculated by applying the Rayleigh-Ritz assumed mode method. The stiffness variation effect caused by the rotating motion is considered in this modeling. The effects of the concentrated mass size, impact position and the angular velocity of the beam on the transient responses are investigated through numerical studies.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.1654-1659
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• 2003

This paper introduces a fast Fourier transform (FFT)-based spectral analysis method for the transient responses as well as the steady-state responses of linear discrete systems. The force vibration of a viscously damped three-DOF system is considered as the illustrative numerical example. The proposed spectral analysis method is evaluated by comparing with the exact analytical solutions as well as with the numerical solutions obtained by the Runge-Kutta method.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 추계학술대회논문집
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• pp.287-290
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• 2000

An efficient dynamic response analysis method of structures supported by nonlinear resilient mounts when subjected to the transient base excitations is presented by using the structural synthesis method in time domain. Through a numerical example, the validity of the presented method is verified by comparison of the results with those of the 'traditional' analysis method.

• 디지털융복합연구
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• 제17권7호
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• pp.125-130
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• 2019

민감도 해석은 어떤 설계 변수의 변화가 전체 시스템에 미치는 영향을 확인하기 위한 방법으로, 계산된 민감도는 구조개선 시 중요한 지표가 된다. 본 연구에서는 유한요소해석을 이용하여 설계 변수에 대한 민감도 도출 및 분석 방법과, 민감도 결과를 활용한 구조개선 방법을 제안하였다. 구조 개선이 필요한 실제 반도체 검사 장비를 이용하여 경량화를 위한 설계 변수를 선정하고 설계 변수에 대한 민감도를 유한요소법과 유한차분법을 활용하여 계산하였으며, 장비가 요구하는 과도응답(Transient Response)은 유지하면서도 무게 감소가 가능한 개선 방안을 제시하였다. 유한요소해석과 유한차분법을 이용한 민감도 분석 결과를 이용한다면 구조물의 설계 개선 시 원하는 응력 또는 변위는 만족하면서도 구조적으로 향상된 설계를 할 수 있고, 이는 반도체 검사 장비뿐만 아니라 다양한 분야에서 활용이 가능하다.

• 대한기계학회논문집B
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• 제33권2호
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• pp.133-140
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• 2009

A fast-response $CO_2$ analyzer has been developed for measuring the $CO_2$ concentration during transient condition of a SI engine. The analyzer consists of the non-dispersive infrared absorption method, electrical chopping system and water cooling system. The analyzer has good repeatability, linearity and permissible drift characteristic. Besides, it showed 18ms of a response to measure the $CO_2$ concentration. The fast-response $CO_2$ analyzer was applied to a single cylinder SI engine and the $CO_2$ emission was examined during engine start. Simultaneously, the standard exhaust gas analyzer, which has slow response time, was used for confirming the accuracy of the exhaust gas analysis using the fast-response $CO_2$ analyzer. The developed analyzer showed much faster responsive characteristic than that of a standard analyzer and made cycle by cycle exhaust gas analysis possible. The transient engine operating characteristics will be estimated from the $CO_2$ concentration of engine-out emissions and engine operating variables.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.174-178
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• 2005

This paper presents a novel fuzzy logic based control method for shunt active filters. Since the fuzzy sets are based on linguistic description, therefore they don't need to the mathematical model of the investigated systems. The proposed method is very suitable to nonlinear and time variant loads. The controller is robust, reliable and it has a smooth response. Also transient response of method is much better than the other classical methods. The simulation results confirm the suitable performance of the filter using this control method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 추계학술대회 논문집 전기물성,응용부문
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• pp.266-269
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• 2003

In this work, a new formulation is presented for analyzing the transient electromagnetic response from wire antennas using the time-domain integral equation. The solution method is based on the Galerkin's method that involves separate spatial and temporal testing procedures. Piecewise triangle basis functions have been used for spatial expansion functions for arbitrarily shaped wire structures. The time-domain variation is approximated by a set of orthonormal basis functions that are derived from the Laguerre polynomials. The method presented in this paper results in very stable transient responses from wire antennas.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제52권9호
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• pp.412-417
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• 2003

In this Paper, we propose a time-domain magnetic field integral equation (TD-MFIE) formulation for analyzing the transient electromagnetic response from three-dimensional (3-D) dielectric bodies. The solution method in this paper is based on the Galerkin's method that involves separate spatial and temporal testing procedures. Triangular patch basis functions are used for spatial expansion and testing functions for arbitrarily shaped 3-D dielectric structures. The time-domain unknown coefficients of the equivalent electric and magnetic currents are approximated tv a set of orthonormal basis function that is derived from the Laguerre polynomials. These basis functions are also used for the temporal testing. Numerical results computed by the proposed method are presented and compared.