• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.21 no.2
• /
• pp.137-145
• /
• 2011

This study is proposed to develop a numerical interaction model of the magnetically levitated(maglev) train and guideway. For this purpose, equation of motion for 6-DOF vehicle model, EMS, guideway and guideway irregularity are derived as the state-space equation. In order to solve the state space equations, the present work was performed via matlab simulation using Runge-Kutta method. Through the simulation, the effect of dynamic response of maglev system to different vehicle speeds, guideway rigidity(EI) and masses is investigated.

• Journal of Applied and Pure Mathematics
• /
• v.4 no.3_4
• /
• pp.151-184
• /
• 2022

In the article, we handle with the existence and controllability results for fractional impulsive neutral functional integro-differential equation in Banach spaces. We have used advanced phase space definition for infinite delay. State dependent infinite delay is the main motivation using advanced version of phase space. The results are acquired using Schaefer's fixed point theorem. Examples are given to illustrate the theory.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.42 no.10
• /
• pp.816-822
• /
• 2014

The estimation of the angular rate of a satellite has been discussed. A nonlinear observer has been proposed based on the state-dependent Riccati equation method. A sufficient stability condition for the convergence of estimation error has been presented. This condition is related to a state-dependent algebraic Riccati equation. It has been derived by transforming nonlinear error dynamics into a Lipschitz nonlinearity. An observer gain is obtained from this condition. Numerical simulations are presented to verify the proposed method.

• Journal of Institute of Control, Robotics and Systems
• /
• v.17 no.9
• /
• pp.897-901
• /
• 2011

This paper presents a TS (Takagi-Sugeno) type FLC (Fuzzy Logic Controller) with only 3 rules. The choice of parameters of FLC is very difficult job on design FLC controller. Therefore, the choice of appropriate linguistic variable is an important part of the design of fuzzy controller. However, since fuzzy controller is nonlinear, it is difficult to analyze mathematically the affection of the linguistic variable. So this choice is depend on the expert's experience and trial and error method. In the design of the system, we use a variety of response characteristics like stability, rising time, overshoot, settling time, steady-state error. In particular, it is important for a stable system design to predict the steady-state error because the system's steady-state response of the system is related to the overall quality. In this paper, we propose the method to choose the consequence linear equation's parameter of T-S type FLC in the view of steady-state error. The parameters of consequence linear equations of FLC are tuned according to the system error that is the input of FLC. The full equation of T-S type FLC is presented and using this equation, the relation between output and parameters can represented. As well as the FLC parameters of consequence linear equations affect the stability of the system, it also affects the steady-state error. In this study, The system according to the parameter of consequence linear equations of FLC predict the steady-state error and the method to remove the system's steady-state error is proposed using the prediction error value. The simulation is carried out to determine the usefulness of the proposed method.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.17 no.3
• /
• pp.3815-3832
• /
• 1975

This study was made to investigate various engineering properties of earth materials resulting from their changes in density and moisture content. The results obtained in this study are summarized as follows: 1. The finner the grain size is, the bigger the Optimum Moisture Content(OMC) is, showing a linear relationship between percent passing of NO. 200 Sieve (n) and OMC(Wo) which can be represented by the equation Wo=0.186n+8.3 2. There is a linear relationship of inverse proportion between OMC and Maximum Dry Density (MDD) which can be represented by the equation ${\gamma}$d=2.167-0.026Wo 3. There is an exponential curve relationship between void ratio (es) and MDD whose equation can be expressed ${\gamma}$d=2.67e-0.4550.9), indicating that as MDD increases, void ratio decreases. 4. The coefficent of permeability increases in proportion to decrease of the MDD and this increase trend is more obvious in coarse material than in fine material, and more obvious in cohesionless soil than in cohesive soil. 5. Even in the same density, the coefficient of permeability is smaller in wet than in dry from the Optimum Moisture Content. 6. Showing that unconfined compressive strength increases in proportion to dry density increase, in unsaturated state the compacted in dry has bigger strength value than the compacted in wet. On the other hand, in saturated state, the compacted in dry has a trend to be smaller than the compacted in wet. 7. Even in the same density, unconfined compressive strength increases in proportion to cohesion, however, when in small density and in saturated state, this relationship are rejected. 8. In unsaturated state, cohesion force is bigger in dry than in wet from OMC. In saturated state, on the other hand, it is directly praportional to density. 9. Cohesion force decreases in proportion to compaction rate decrease. And this trend is more evident in coarse matorial than in fine material. 10. Internal friction angle of soil is not influenced evidently on the changes of moisture content and compaction rate in unsaturated state, On the other hand in saturated state it is influenced density. 11. Cohesion force is directly proportional to unconfined compressive strength(qu), indicating that it has approximately 35 percent of qu in unsaturated state and approximately 70 percent of qu in saturated state.

• Journal of computational fluids engineering
• /
• v.17 no.3
• /
• pp.99-107
• /
• 2012

In this paper, the shock waves in compressible solids and liquids are simulated using a six-equation diffuse interface multiphase flow model that is extended to the Cochran and Chan equation of state. A pressure relaxation method based on a volume fraction function and a pressure-correction equation are newly implemented to the six-equation model. The developed code has been validated by a shock tube problem with liquid nitromethane and an impact problem of a copper plate on a solid explosive. In addition, a new problem, an impact of a copper plate on liquid nitromethane, has been solved. The present code well shows the wave structures in compressible solids and liquids without any numerical oscillations and overshoots. After the impact of a solid copper plate on liquid, two shock waves (one propagates into liquid and the other into solid) are generated and a material interface moves to the impacting direction. The computational results show that the shock velocity inside the liquid linearly increases with the impact velocity.

• Transactions of the Korean hydrogen and new energy society
• /
• v.34 no.2
• /
• pp.162-168
• /
• 2023

The fast refueling process of compressed hydrogen has an important impact on the filling efficiency and safety. With the development and use of hydrogen energy, the demand for precision measurement of filling hydrogen thermodynamic parameters is also increasing. In this paper, the compressibility factor calculation model of high-pressure hydrogen gas was studied, and the basic equation of state and thermo-physical parameters were calculated. The hydrogen density data provided by the National Institute of Standards and Technology was compared with the calculation results of each model. Results show that at a pressure of 0.1-100 MPa and a temperature of 233-363 K, the calculation accuracy of the Zheng-Li equation of state was less than 0.5%. In the range of 0.1-70 MPa, the accuracy of Redich-Kwong equation is less than 3%. The hydrogen pressure more influences on the compressibility factor than the hydrogen temperature does. Using the Zheng-Li equation of state to calculate the compressibility factor of on-board high pressure hydrogen can obtain high accuracy.

• Journal of Electrical Engineering and Technology
• /
• v.13 no.5
• /
• pp.1927-1934
• /
• 2018

In this paper, we studied the state of charge (SOC) estimation algorithm of a high-capacity lithium secondary battery for electric vehicles (EVs) considering temperature characteristics. Nonlinear characteristics of high-capacity lithium secondary batteries are represented by differential equations in the mathematical form and expressed by the state space equation through battery modeling to extract the characteristic parameters of the lithium secondary battery. Charging and discharging equipment were used to perform characteristic tests for the extraction of parameters of lithium secondary batteries at various temperatures. An extended Kalman filter (EKF) algorithm, a state observer, was used to estimate the state of the battery. The battery capacity and internal resistance of the high-capacity lithium secondary battery were investigated through battery modeling. The proposed modeling was applied to the battery pack for EVs to estimate the state of the battery. We confirmed the feasibility of the proposed study by comparing the estimated SOC values and the SOC values from the experiment. The proposed method using the EKF is expected to be highly applicable in estimating the state of the high-capacity rechargeable lithium battery pack for electric vehicles.

• Coupled systems mechanics
• /
• v.9 no.1
• /
• pp.77-89
• /
• 2020

This study is dedicated to the dynamic elasticity problem for a semi-strip. The semi-strip is loaded by the dynamic load at the center of its short edge. The conditions of fixing are given on the lateral sides of the semi-strip. The initial problem is reduced to one-dimensional problem with the help of Laplace's and Fourier's integral transforms. The one-dimensional boundary problem is formulated as the vector boundary problem in the transform's domain. Its solution is constructed as the superposition of the general solution for the homogeneous vector equation and the partial solution for the inhomogeneous vector equation. The matrix differential calculation is used for the deriving of the general solution. The partial solution is constructed with the help of Green's matrix-function, which is searched as the bilinear expansion. The case of steady-state oscillations is considered. The problem is reduced to the solving of the singular integral equation. The orthogonalization method is applied for the calculations. The stress state of the semi-strip is investigated for the different values of the frequency.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.53 no.3
• /
• pp.129-134
• /
• 2004

To analyze the performance of the gas circuit breaker(GCB), the flow field variables such as temperature, pressure and density should be evaluated accurately In the puffer chamber of puffer type GCB, the pressure rise may Exceed 20 bar and in this range of high pressure, $SF_6$ gas deviates the ideal gas property. Therefore, the real gas property of $SF_6$ should be taken into consideration for the accurate analysis of flow field. This paper presents the analysis technique of cold gas flow in GCB employing the real gas state equation of SF6. The FVFLIC method is Employed to solve the axisymmetric Euler equation. To reduce the computational effort of real gas state equation, the relationship between density and pressure is approximated by the polynomial at the temperature of 300K. The proposed method is applied to the test GCB model and simulation results show good agreement with the experimental ones.