• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2005.03a
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• pp.405-412
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• 2005

In this study, a numerical method for soil-pile-structure interaction problems in multi-layered half-plane is developed. The total soil-pile-structure interaction system is divided into two parts namely, nonlinear structure part and linear soil-pile interaction parts. In the structure field, the general finite element method is introduced to solve the dynamic equation of motion for the structure. In the soil-pile structure interaction part, physical model consisting of lumped parameter, which is frequency dependent coefficient and determined by rigorous analysis method is introduced. Using proposed analysis procedure, the nonlinear behavior of structure considering soil-structure interaction can be efficiently determined in time domain and the analysis cost is dramatically reduced.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.183-188
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• 2004

Nowadays optical disc drives have become necessary. As the equipment is popular to use, competition of price and rotating rate have been harder and harder. Shock response analysis for the optical disk drives is rarely studied. In this paper the optical disk drive has 5-DOF system and each motion is presented by using Lagrange Equation. As the motion of the Pick up lens is important to read and write data, it needs to consider the pickup and disk. The lumped parameter model is compared with finite element model in order to make sure of the result. Results of the shock response analysis from various shock inputs are gotten.

• International Journal of Precision Engineering and Manufacturing
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• v.7 no.2
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• pp.56-59
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• 2006

A vibrational model of powder transfer equipment based on the lumped parameter method was developed, in which the operating motion consists of surging, bouncing, and pitching. After decoupling the equation of motion, the vibrational excitation source of the pitching motion was removed. So the designers are able to plan the optimum design to adjust the motion trajectory of the powder transfer equipment. That is, a procedure to adjust the motion trajectory of powder transfer equipment by changing design specifications such as the installation position, the direction of the motor, the driving speed, the mass unbalance, the stiffness coefficient, and the installation position of the support spring, is presented in this paper. The powder transfer equipment manufactured according to the results of this study did not suffer fatigue destruction, since the maximum stress on the basket structure was sufficiently small.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1679-1682
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• 2008

Pulsatile Extracorporeal Membrane Oxygenation(ECMO) can mitigate the heart load and raise the patient's blood perfusion. But If the ECMO pulsate the blood flow during the systolic period, It can burden to the patient's heart. To avoid the heart injury, we have to consider the relation between output of ECMO, hemodynamic states and heart movement. To raise the efficacy of the pulsatile ECMO, we investigated the coronary perfusion, cardiac muscle tension and hemodynamic states during the ECMO perfusion by using the mathematical model of human blood circulatory system and ECMO. The outflow data of the pulsatile ECMO(T-PLS, Bioheartkorea, Korea) was obtained in vitro experiments. According to the phase and pumping rate of the ECMO, the heart's load and coronary perfusion could be adjusted to the proper levels. The results of the human- ECMO lumped parameter model showed that the synchronizing operation of the pulsatile ECLS can be helpful at stabilizing the patient's hemodynamic states.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1648-1653
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• 2003

This paper predicts the modified proportional damping structural eigenvectors and eigenvalues due to the change in the mass and stiffness of a proportional damping structure by iterative calculation of the sensitivity coefficient using the original dynamic characteristics. The method is applied to examples of a cantilever and 3 degree of freedom lumped mass model by modifing the mass and stiffness. The predicted dynamic characteristics are in good agreement with these from the structural reanalysis using the modified mass and stiffness.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1997.04a
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• pp.241-248
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• 1997

The super-structure in a soil-structure interaction analysis is commonly idealized as lumped parameter system. In this study, the complex shear wall structure is modeled using three different kinds of modeling techniques : 1) full FEM comparatively as an exact solution, 2)equivalent shear spring model assuming mainly shear deformations of the wall, 3) equivalent beam-stick model made by independent static analysis. Dynamic characteristics due to three different modeling methods are compared and investigated before performing structural response analysis. The beam-stick model in comparison to shear spring model gives closer dynamic responses when compared with the full FEM, even though it requires additional unit load static analyses.

• Journal of Electrical Engineering and Technology
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• v.7 no.3
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• pp.297-303
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• 2012

This paper presents the simulation results for the analysis of a lightning surge, switching transients and very fast transients within a thermal plant. The modeling of gas insulated substations (GIS) makes use of electrical equivalent circuits that are composed of lumped elements and distributed parameter lines. The system model also includes some generators, transformers, and low voltage circuits such as 24V DC rectifiers and control circuits. This paper shows the simulation results, via EMTP (Electro-Magnetic Transients Program), for three overvoltage types, such as transient overvoltages, switching transients, very fast transients and a lightning surge.

• Journal of Advanced Marine Engineering and Technology
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• v.17 no.4
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• pp.87-99
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• 1993

Nowadays, the cartridge valve can be controlled proportionally in remote place by adopting proportional solenoid and it becomes widely used as control component in hydraulic systems. Especially, multi stage proportional valve is attractive because it consumes less input power though its characteristics might slightly be defected. But, the system parameter should be carefully chosen to obtain optimistic characteristics. This study concerning three stage proportional throttle control valve is purposed to examine the influences of paameters to the dynamic characteristics. The typical transient and frequency responses of proportional throttle control valve were inspected through the experiments and compared to those derived from the theoritical analyses. And it was confirmed that the analyses are appropriate. Then the influences of various system parameters to the dynamic characteristics were examined by means of simulations. For the analyses, the basic equations derived from lumped model were linearized and the linearized equations were transformed to the transfer functions between inputs and outputs. Then the transient responses and frequency responses were obtained from transfer functions. 1. It is appropriate to estimate the dynamic characteristics of valve which has relatively sophisticated structure by means of system analyses using linearized equations. 2. Though the valve has two pilot stages, fairly good characteristics can be obtained by carefully choosing system parameters. 3. Main valve very quickly follows the movement of second pilot valve when the parameters of main valve(the oil supply passage and discharge passage fpr second pilot valve) are appropriately chosen.

• Transactions of the Korean Society of Mechanical Engineers
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• v.8 no.5
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• pp.416-424
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• 1984

A numerical and experimental investigation was carried out on the single-phase natural circulation system. This study is concerned with the multiloop system which is relevant to the primary system of the pressurized water reactor. For numerical analysis, five time-dependent governing equations were derived using the one-dimensional lumped parameter model. These equations were discretized by the space-time integration technique, and a simplified computer program, SIMFARS, was developed to solve those discretized equations. Experiments were performed for two purposes-one is to validate the developed code, and the other is to understand the qualitative behavior of the natural circulation loop. Comparison of the computational results with experiments, and several experimental and numerical results are presented in this article.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2001.09a
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• pp.117-124
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• 2001

A simplified method fur the eigenpair sensitivities of damped system with multiple eigenvalues is presented. This approach employs a reduced equation to determine the sensitivities of eigenpairs of the damped vibratory systems with multiple natural frequencies. In the proposed method, adjacent eigenvectors and orthonormal conditions are used to compute an algebraic equation whose order is (n+m)x(n+m), where n is the number of coordinates and m the number of multiplicity of multiple natural frequencies. The proposed method is an improved Lee and Jung's method which was developed previously. Two equations are used to find eigenvalue derivatives and eigenvector derivatives in Lee and Jung's method. A significant advantage of this approach over Lee and Jung's method is that one algebraic equation newly developed is enough to compute such eigenvalue derivatives and eigenvector derivatives. This method can be consistently applied to both structural systems with structural design parameters and mechanical systems with lumped design parameters. To demonstrate the theory of the proposed method and its possibilities in the case of multiple eigenvalues, the finite element model of the cantilever beam and 5-DOF mechanical system in the case of a non-proportionally damped system are considered as numerical examples. The design parameter of the cantilever beam is its height. and that of the 5-DOF mechanical system is a spring.