• Earthquakes and Structures
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• v.8 no.1
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• pp.101-132
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• 2015

This research formulates a closed-form equation to predict a glass panel cracking failure drift for several curtain wall and storefront systems. An evaluation of the ASCE 7-10 equation for Dclear, which is the drift corresponding to glass-to-frame contact, shows that the kinematic modeling assumed for formulation of the equation is sound. The equation proposed in this paper builds on the ASCE equation and offers a revision of that equation to predict drift corresponding to cracking failure by considering glazing characteristics such as glass type, glass panel configuration, and system type. The formulation of the proposed equation and corresponding analyses with the ASCE equation is based on compiled experimental data of twenty-two different glass systems configurations tested over the past decade. A final comparative analysis between the ASCE equation and the proposed equation shows that the latter can predict the drift corresponding to glass cracking failure more accurately.

• 전기의세계
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• v.21 no.2
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• pp.9-19
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• 1972

The transient characteristics of separately excited d-c motor driven by thyristor d-c chopper is studied in this paper. The armature controlled system is applied. As a result of theoretrical analysis the following conculsions were drawn: (1) For the transient analysis, it is recognized that the state transition analysis is a more general method and powerful tool than the state equation method or signal flow graph method, although it includes iterative matrix calculations. And the system is dealt with a finite width sampled-data system in the state transition analysis. (2) The transient characteristics of the motor angular velocity and its torque to the sampling duration variation are compared with those due to the amplitude variation of d-c chopper voltage as follows. The attenuation rate of the transient characteristics is equal in both cases, but the initial value of the transient characteristics in former case is greater than in latter case. (3) The roots of characteristics equation of the system lie inside the unit circle of the Z-plane. Therefor the system is stable. Further it is found that as the sampling duration is decreased the relative stability is lessened.

• Structural Engineering and Mechanics
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• v.59 no.6
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• pp.1139-1153
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• 2016

Elastic constraints are usually simplified as "spring forces" exerted on beam ends without considering the "spring deformation". The partial differential equation governing the free vibrations of a cantilever Bernoulli-Euler beam considering the deformation of elastic constraints is firstly established, and is nondimensionalized to obtain two dimensionless factors, $k_v$ and $k_r$, describing the effects of elastically vertical and rotational end constraints, respectively. Then the frequency equation for the above Bernoulli-Euler beam model is derived using the method of separation of variables. A numerical analysis method is proposed to solve the transcendental frequency equation for the continuous change of the frequency with $k_v$ and $k_r$. Then the mode shape functions are given. Finally, effects of $k_v$ and $k_r$ on free vibration characteristics of the beam with different slenderness ratios are calculated and analyzed. The results indicate that the effects of $k_v$ are larger on higher-order free vibration characteristics than on lower-order ones, and the impact strength decreases with slenderness ratio. Under a relatively larger slenderness ratio, the effects of $k_v$ can be neglected for the fundamental frequency characteristics, while cannot for higher-order ones. However, the effects of $k_r$ are large on both higher- and lower-order free vibration characteristics, and cannot be neglected no matter the slenderness ratio is large or small.

• Korean Journal of Hydrosciences
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• v.6
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• pp.51-66
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• 1995

Various Eulerian-Lagerangian numerical models for the one-dimensional longtudinal dispersion equation are studied comparatively. In the models studied, the transport equation is decoupled into two component parts by the operator-splitting approach ; one part governing advection and the other dispersion. The advection equation has been solved using the method of characteristics following flud particles along the characteristic line and the result are interpolated onto an Eulerian grid on which the dispersion equation is solved by Crank-Nicholson type finite difference method. In solving the advection equation, various interpolation schemes are tested. Among those, Hermite interpo;ation po;ynomials are superor to Lagrange interpolation polynomials in reducing both dissipation and dispersion errors.

• Proceedings of the KSR Conference
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• 2001.10a
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• pp.475-480
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• 2001

In this study, a empirical equation which can be feasibly used to evaluate minimal track buckling strength without exact numerical analysis is presented. Parameter studies we carried out to investigate the effects of the individual factor on buckling strength. In order to simulate track buckling in the field as precisely as possible, a rigorous buckling model which accounts for all the important parameters is adopted. A empirical equation for prediction of minimal track buckling strength is derived by taking nonlinear regression of data which are obtained from numerical analyses. Its characteristics and applicability are investigated by comparing the results by the presented equation with the one by the equation which was presented in japan, and is frequently using in korea when designing track structure.

• Journal of KSNVE
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• v.9 no.3
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• pp.502-508
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• 1999

Newly developed control methodology applied to dynamic system under random disturbance is investigated and its performance is verified experimentall. Flexible cantilever beam sticked with piezofilm sensor and piezoceramic actuator is modelled in physical domain. Dynamic moment equation for the system is derived via Ito's stochastic differential equation and F-P-K equation. Also system's characteristics in stochastic domain is analyzed simultaneously. LQG controller is designed and used in physical and stochastic domain as wall. It is shown experimentally that randomly excited beam on the base is controlled effectively by designed LQG controller in physical domain. By comparing the result with that of LQG controller designed in stochastic domain, it is shown that new control method, what we called $\ulcorner$Heo-stochastic controller design technique$\lrcorner$, has better performance than conventional ones as a controller.

• Journal of Ocean Engineering and Technology
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• v.15 no.2
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• pp.6-10
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• 2001

Water waves propagate over irregular bottom bathymetry are transformed by refraction, diffraction, shoaling, reflection etc. Principal factor of wave transform is bottom bathymetry, but in case of current field, current is another important factor which effect wave transformation. The governing equation of this study is develope as wave-current equation type to investigate the effect of wave-current interaction. It starts from Berkhoff's(1972) mild slope equation and is transformed to time-dependent hyperbolic type equation by using variational principal. Finally the governing equation is shown as a parabolic type equation by splitting method. This wave-current model was applied to the kwangan beach which is located at Pusan. The numerical simulation results of this model show the characteristics of wave transformation and flow pattern around the Kwangan beach fairly well.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.2
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• pp.87-97
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• 2013

Recently the use of gas spring in the combat and commercial vehicle's suspension is increasing. Because of its nonlinear characteristics, the gas spring can support wide range of dynamic loads and gives good ride quality. In design of gas spring, isothermal and adiabatic processes are applied generally, but those processes could not produce heat transfer effect in the simulation. So in this study, heat transfer differential equation and BWR/Ideal state equation are used to calculate the pressure of gas spring which is changing with time. The numerical analysis showed that the pressure of gas spring forms a hysteresis loop in the both of the state equations. But the peak pressure value of BWR equation over 0.1Hz frequency are higher than that of adiabatic process. And the test results showed that the differences between test results and ideal gas equation are smaller than those of BWR equation, so the ideal equation is more accurate than BWR equation in this case.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.06a
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• pp.291-296
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• 1999

This study presents a method for determining stiffness and damping coefficients of 30% U slider-air bearings by using perturbation method, and shows that this method is more accurate than steady state method according to the comparison of those with the modal analysis method. Through a generalized lubrication equation, which based on linealized Boltzmann equation, the static and dynamic pressure distributions are calculated by finite volume method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.332-335
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• 2007

This paper presents a theoretical approach to describe the vibration characteristics of a piezoelectric shell transducer. Governing equations for the motion of the piezoelectric shell are classified and simplified according to the boundary conditions. Applied mechanical and electrical boundary conditions have yielded each characteristic equation for circumferential, longitudinal, and radial motions of the piezoelectric shell transducer. Theoretical calculations of the resonance frequencies have been compared with the results obtained by the experiment and have shown a good agreement.