• 한국기계가공학회지
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• 제16권6호
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• pp.47-54
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• 2017

This study analyzed air suspension seat frame structure and vibration for 50 - 180 kg mass driver to obtain optimum seat design parameter values for the equivalent spring constant and damping coefficient. Various air suspension seat frames were designed following WTS-003 and KS B 6839 standards, and then evaluated using finite elements analysis. Resonance and vibration tests were performed according to the 78/764/EEC standard.

• 한국자동차공학회논문집
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• 제13권4호
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• pp.105-112
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• 2005

Analyses of dynamic models which were one and two degrees of freedom, and had the nonlinear springs and dampings with certain polynomial functions were performed from SIMULINK in MATLAB. Those consisted of 12 programs and were built on the basis of the preceding programs fur the linear dynamic simulations. However the programs for the nonlinear simulations were quite different from those f3r the linear ones, and showed the results of the analyses in real time with animating. It was found that the programs would help us to solve any kind of nonlinear dynamic simulation with one and two degrees of freedom. Especially, the simulations for 1 DOF system with cubic nonlinear spring farce showed the results for Duffing's equation, of which phenomena were jump-up and jump-down. It will be applied to the dynamic simulation of the car seat vibration with a passenger, of which model has the equivalent nonlinear springs and is two degrees of freedom.

• 조명전기설비학회논문지
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• 제15권3호
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• pp.83-90
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• 2001

본 논문은 전력계통에 저주파수 동요현상을 제거하기 위한 목적으로 쓰이고 있는 전력계통 안정화 장치의 적정 파라메타 선정에 관한 알고리즘을 다루었다. 실측에 의한 발전기 시스템의 모델로부터 시스템 제 정수를 구하고, 극좌표 이동법으로 적절한 전력계통 안정화 장치의 파라메타를 Matlab으로 작성하여 구했다. 이 기법으로 선정된 전력계통 안정화 장치의 파라메타로 1기 무한대 계통에 적용한 시뮬레이션 결과는 만족한 만큼의 댐핑 효과를 보았다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.647-650
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• 2004

The modeling of an active vibration isolation system is accomplished by using the equivalent spring constant, mass and rotational Inertia of each component. The detailed model of the actuation module is successful for describing its frequency-domain performance but also too complicated to implement it to actual system for control so that the order of the model is reduced up to the degree that preserves its characteristic in the low frequency range. The reduced model is suitable for identifying the unknown system parameters such as damping constants of components. The overall isolation system is described by using the reduced model of the actuation module. The accurate model ing and system parameter identification that is essential for the control of the active vibration isolation system is attained successfully.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.217-222
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• 2005

Active vibration control of smart hull structure using Macro Fiber Composite (MFC) actuator is performed. Finite element modeling is used to obtain governing equations of motion and boundary effects of end-capped smart hull structure. Equivalent interdigitated electrode model is developed to obtain piezoelectric couplings of MFC actuator. Modal analysis is conducted to investigate the dynamic characteristics of the hull structure, and compared to the results of experimental investigation. MFC actuators are attached where the maximum control performance can be obtained. Active controller based on Linear Quadratic Gaussian (LQG) theory is designed to suppress vibration of smart hull structure. It is observed that closed loop damping can be improved with suitable weighting factors in the developed LQG controller and structural vibration is controlled effectively.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2006년도 학술발표회 논문집
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• pp.537-544
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• 2006

In this study, performance level evaluation tests have been actually performed on laminated rubber seismic isolation bearings (LRB) made in Korea. To provide basic data for setting up fabrication criteria and performance evaluation criteria three real scale LRB were tested and the test results were analysised. Accordingly, a large capacity test device has been designed and manufactured to implement the tests. The device selected for evaluation is a circular LRB actually applied in bridges. Evaluation tests were conducted using full-scale LRB with diameter of 851mm in the rubber part and total height of 215mm of which the effective horizontal stiffness and equivalent damping ratio have been measured during the experiments.

• Structural Engineering and Mechanics
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• 제10권2호
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• pp.139-156
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• 2000

This paper concerns the development of a computational model for the damage evolution of engineering materials under dynamic loading. Two models describing the anisotropic damage evolution of a material are presented; the first is based on a power function of the effective equivalent stress and the second on the damage strain energy release rate. The methods for computing the damage accumulated in structural components and their implementation in a finite element programme are presented together with some numerical results. The dynamic response of a damaged structural component and the dynamic behaviour of a damaged material have been studied numerically. This study shows that the frequency spectrum of a damaged structure is down-shifted, while the damping ratio of damaged materials becomes higher, the amplitude of the response significantly increases and the resonance ensuing from the damage growth still occurs in a damaged structure.

• 대한조선학회지
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• 제7권2호
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• pp.61-70
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• 1970

Since there has been no analytical method to calculate principal dimensions of the axial vibration damper of marine diesel engine shaftings in design state, it has often happened to install the axial vibration damper after the ship's trial trip. In this paper a method to calculate the coefficient of equivalent damping of the axial vibration damper is introduced and with this value one can calculate fairy accurate vibrating amplitudes of the crankshaft that is fitted with an axial vibration damper, by using author's matrix methods.[1][2][3][4] A comparison of the calculated amplitudes with measured ones is shown and its result is fairy good, except values of the case where the damper nozzle is almost closed.

• Wind and Structures
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• 제28권2호
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• pp.89-97
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• 2019

The non-linear equations governing wind-induced internal pressures for a two-compartment building with background leakage are linearized based on some reasonable assumptions. The explicit admittance functions for both building compartments are derived, and the equivalent damping coefficients of the coupling internal pressure system are iteratively obtained. The RMS values of the internal pressure coefficients calculated from the non-linear equations and linearized equations are compared. Results indicate that the linearized equations generally have good calculation precision when the porosity ratio is less than 20%. Parameters are analyzed on the explicit admittance functions. Results show that the peaks of the internal pressure in the compartment without an external opening (Compartment 2) are higher than that in the compartment with an external opening (Compartment 1) at lower Helmholtz frequency. By contrast, the resonance peak of the internal pressure in compartment 2 is lower than that in compartment 1 at higher Helmholtz frequencies.

• 한국공간구조학회논문집
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• 제22권1호
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• pp.51-57
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• 2022

In this paper, based on the finite element analysis model verified in previous studies, a new model of a buckling restrained brace reinforced with a steel plate was proposed. A design formula was proposed for the new model to dissipate energy without buckling the steel core under load protocol, and the performance of the model satisfying the design formula was evaluated by comparing it with the previous model through the results of hysteresis loop, bi-linear curve, cumulative energy dissipation capacity, and equivalent viscous damping.