• Tribology and Lubricants
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• v.17 no.1
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• pp.56-63
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• 2001

The dynamic behavior of rotor-bearing system used in swash plate compressor has been investigated using the combined methodologies of finite elements and transfer matrices. The finite element is formulated including the field element for a shaft section and the point element for swash plate, disk pulley and bearings. The Houbolt method is used to consider the time march for the integration of the system equations. The transient whirl response of rotating shaft supported on roller bearings is obtained, considering compression forces and unbalance forces at swash plate and driving pulley. And, the steady state displacements of the rotor are compared with a variation in unbalance mass. Results show that the loci of rotating shaft considering unbalance forces and external compression forces are more severe in flutter motion than with only unbalance forces.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.566-572
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• 2000

The System identification is the process of developing or improving a mathematical model of a physical system using experimental data of the input, output and noise relationship. The field of system identification has been an important discipline within the automatic control area. The reason is the requirement that mathematical models having a specified accuracy must be used to apply modem control methods. In this paper, it is confirmed that we can obtain transfer function of flexible beam that is expressed in the forms of identified state-space system matrix A, B, C, D and identified observer gain G using Eigensystem Realization Algorithm including singular value decomposition. And these matrices can be applied to the automatic control. In addition to, it is also confirmed that transfer function can express a system using identified observer gain G, in spite of a noisy data or a periodic disturbance.

• 전기의세계
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• v.23 no.2
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• pp.46-54
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• 1974

The purposes of this paper are to deal with the design of m-input, m-output linear systems by the state variable feedback, and to extend the design capability of the state variable feedback design. The design requirements are decoupling and the exact realigation of desired transfer functions. Some methods are proposed to insert series compensators in the fixed plant in the cases when series compensators are needed to meet the input-output transfer matrix specification. The method for adding series compensators to the input channels of the fixed plant is shown by examples to lead both to the loss of the ability to decouple the augmented plant by the state variable feedback, and to the loss of desired zeroes. A method which avoids these two hazards is developed in which series compensators are put on the output channels of the fixed plant: it is proved that the augmented plant is F-invariant. By treating each subsystem individually, the designer can apply some of the previous developed knowledge of the state variable design of single-input, single-output systems.

• Journal of KSNVE
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• v.10 no.6
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• pp.977-984
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• 2000

Vibration of disk drive spindle is one of the major limiting factors in achieving higher track densities in hard disk drives. Vibration of a BLDC motor is a coupled phenomenon between mechanical characteristics and magnetic origins through the motor air-gap. In this paper, radial magnetic forces for symmetric and asymmetric BLDC motor are calculated with respect to the various rotor eccentricity using analytic method. Based on the results of the radial magnetic forces, transient whirl responses of the spindle motor are analyzed using finite element and transfer matrices. Results show that an asymmetric motor has a worse effects on unbalanced magnetic forces and vibration when mechanical and magnetic coupling exists.

• Proceedings of the KWS Conference
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• 2005.11a
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• pp.135-137
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• 2005

The body of the work covers FSW welding of Al6061 and its thermal distribution based on an analytical model for the heat input at the probe/matrix boundary of Al plates and FSW tool due to the effect of combined translation and rotational motion of the tool pin and shoulder. Finally the 2D- finite element heat transfer analysis program has been used to plot the heat distribution at the Friction Stir Welded joint in Al 6061 plate. The work concludes that the heat distribution result obtained from FE analysis has a reasonable agreement with the experimentally measured values.

• International Journal of Air-Conditioning and Refrigeration
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• v.13 no.2
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• pp.83-88
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• 2005

This study investigates the air leakage and heat transfer characteristics of a commercially available rotary-type air-to-air heat exchanger with a fiber polyester matrix. Crossover leakage between the exhaust and supply air is measured using a tracer gas method for various ventilation rates and rotational speeds of the wheel. A correlation equation for the leakage is obtained by summing up pressure leakage and carryover leakage. The pressure leakage is observed to be a function of ventilation rate only, and the carryover leakage is found to be a linear function of wheel speed. The real efficiency of the heat exchanger can be obtained from its apparent efficiency by taking into account the leakage ratio. The heat recovery efficiency decreases, as the ventilation rate increases. As the wheel speed increases, however, the efficiency increases initially but reaches a constant value for the speeds over 10rpm.

• Proceedings of the KSR Conference
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• 2001.05a
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• pp.123-128
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• 2001

Numerical simulation is conducted to clarify the heat transfer and fluid flow characteristics of brake shoe for freight car. High order up-wind scheme for governing equations, k-epsilon turbulent model and SIMPLEC algorithm based on finite volume method are used to solve the physical shoe model. The governing equations are solved by TDMA(Tri-Diagonal Matrix Algorithm) with line-by-line method and block correction. From the results of simulation, the characteristics of cooling pattern is strongly affected by the velocity of train and the material of shoe. The face lift of shoe affects on the temperature distribution of rear surface of shoe as well as the front surface of that. Due to the grooves in shoe, it will be expected to cool the frictional heat and result in the reduction of maintenance efforts.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.1B
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• pp.35-41
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• 2010

In this paper, we propose a 3D view design scheme which arranges 2D information in a 3D virtual space with a flexible interface and voice information. The scheme allows the user interface of the 2D image in 3D virtual space anytime from any view point. Voice information can be easily attached. It is this simple and efficient image and voice information arrangement in 3D virtual space that improves information transfer.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1996.10a
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• pp.203-209
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• 1996

The authors apply the transfer influence coefficient method to the 3-dimensional vibration analysis of beam with multi-joints and formulate a general algorithm to analysis the longitudinal, flexural and torsional coupled forced vibration. In this paper, a structure, which is mainly founded in the robot arms, cranes and so on, has some crooked parts, subsystems and joints but has no closed loop in this system. It is modeled as the beam of a distributed mass system with massless translational, rotational and torsional springs in each node, and joint elements of release or roll at which node the displacement vector is discontinuous. The superiority of the present method to the transfer matrix method in the computation accuracy was confirmed from the numerical computation results. Moreover, we confirmed that boundary and intermediate conditions could be controlled by varying the values of the spring constants.

• Proceedings of the KSR Conference
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• 1999.11a
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• pp.93-98
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• 1999

Numerical simulation is conducted to clarify the heat transfer and fluid flow characteristics of brake disk-lining for rolling stock. Multiple rotational reference frame, k-epsilon turbulent model and SIMPLE algorithm based on finite volume method are used to solve the physical disk-lining model. The governing equations are solved by TDMA(TriDiagonal Matrix Algorithm) with line-by-line method and block correction, From the results of simulation, the characteristics of cooling pattern is strongly affected by the grooves in lining. The face lift of lining affects on the temperature distribution of rear surface of lining as well as the front surface of that. Due to the grooves in lining, it will be expected to extend the maintenance life circle of lining.