• 한국윤활학회:학술대회논문집
• /
• 한국윤활학회 2001년도 제34회 추계학술대회 개최
• /
• pp.273-281
• /
• 2001

Feasibility study of gas-lubricated bearing in micro gas turbine was performed. Based on Reynolds equation, finite difference method with coupled boundary was developed to analyze bearing characteristics, such as load-carrying capacity, mass flow rates and stiffness. By the bearing force and mass flow rates analysis with the variation of supply pressure, bearing clearance and capillary radius, acceptable range of design parameters were suggested in terms of load capacity and stiffness of bearings. Additionally, coupled boundary effect on pressure distribution was investigated and it is stated that coupling could reduce all excitation force due to narrow pressure distribution.

• 대한전기학회논문지
• /
• 제39권1호
• /
• pp.29-35
• /
• 1990

This paper proposes a tow-dimensional magnetic flux distribution analysis of the double-sided linear induction motor(DLIM). Both the longitudinal end-effect and the transverse edge-effect, which are due to the finite length and width of the primary stator, are considered. Also each force which is due to the variation of slip frequency was computed to show the fact that the thrust force of DLIM is dependent on both the longitudinal end-effect and the transverse edge-effect. To ascertain the propriety of this analysis, the simulated results of the magnetic flux density distribution in the airgap are compared to the experimental data.

• International Journal of Precision Engineering and Manufacturing
• /
• 제6권1호
• /
• pp.65-72
• /
• 2005

Drilling process is one of the most common, yet complex operations among manufacturing processes. The performance of a drill is largely dependent upon drilling forces, Many researches focused on the effects of drill parameters on drilling forces. In this paper, an effective theoretical model to predict thrust and torque in drilling is presented. Also, with the predicted forces, the stress analysis of the drill tool is performed by the finite element method. The model uses the oblique cutting model for the cutting lips and the orthogonal cutting model for the chisel edge. Thrust and torque are calculated analytically without resorting to any drilling experiment, only by tool geometry, cutting conditions and material properties. The stress analysis is performed by the commercial FEM program ANSYS. The geometric modeling and the mesh generation of a twist drill are performed automatically. From the study, the effects of the variation of the geometric features of the drill and of the cutting conditions of the drilling on the drilling forces and the stress distributions in the tool are calculated analytically, which can be applicable for designing optimal drill geometry and for improving the drilling process.

• International Journal of Naval Architecture and Ocean Engineering
• /
• 제7권2호
• /
• pp.364-374
• /
• 2015

The purpose of this research is to compare and analyze the advanced speed of ships with different rudder controller in wavy condition by using a simulation. The commercial simulation tool named AQWA is used to develop the simulation of ship which has 3 degree of freedom. The nonlinear hydrodynamic force acting on hull, the propeller thrust and the rudder force are calculated by the additional subroutine which interlock with the commercial simulation tool, and the regular wave is used as the source of the external force for the simulation. Rudder rotational velocity and autopilot coefficients vary to make the different rudder controller. An advanced speed of ships depending on the rudder controller is analyzed after the autopilot simulations.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2008년도 추계학술대회 논문집
• /
• pp.310-315
• /
• 2008

Authors design a rotary-type small-scaled linear induction motor(LIM) and a performance test machine before manufacturing a real-scaled LIM for a railway transit. The designed LIM is a single-sided, short primary type and its primary has 4 poles. The rated power is 10(kW). In order to analyze characteristics of the LIM, authors use a mixed 2D-3D FEM analysis. 3-D FEM analysis is used for calculating a distribution of eddy-current on the semi-caped AL-sheet of the secondary reaction. Authors calculate a correction factor of conductivity and an equivalent conductivity on the secondary AL-sheet using a normalized eddy-current. The equivalent conductivity which is calculated in this way includes a transverse edge-effect of the LIM. Authors apply the equivalent conductivity on the secondary AL-sheet of 2D-FEM model and get performance characteristics of the LIM. Basic characteristics such as thrust and normal force, input current, efficiency and power factor of the LIM have been analyzed with the variation of frequency and speed. In order to apply an air-gap control system, the variation of the basic characteristics have been analyzed with the air-gap length variation of the LIM. Finally, authors introduce an operation mode using the air-gap control system and conduct a research on feasibility of the system.

• 전기학회논문지P
• /
• 제60권2호
• /
• pp.82-90
• /
• 2011

The small precision spindle motors in the high value-added products including the visible home appliances such as DLP projector require not only the energy conversion devices but also high efficiency, low vibration and sound operation. However, the spindle motors using the conventional ball bearing and sintered porous metal bearing have following problems, respectively: the vibration by the irregularity of balls and the short motor life cycle by the ball's abrasion and higher sound noises by dry contact between shaft and sleeve. In this paper, it is proposed that the spindle motor with a fluid dynamic bearing is suitable for the motor to drive the color wheel of the DLP(digital lightening processor) in the visible home appliances. The proposed spindle motor is composed of the fluid dynamic bearing with both the radial force and the thrust force. The fluid dynamic bearing is solved by the finite element analysis of the mechanical field with the Reynolds equations. The magnetic part of spindle motor, which is a type of Brushless DC Motor, is designed by the electro-magnetic field analysis coupled with the Maxwell equation. And the load capacity and the friction loss of fluid dynamic bearing are analyzed to bearing clearance variation by the fabrication error in designed motor. The design of the proposed motor is implemented by the load torque caused by the eccentricity and the unbalance of the fluid dynamic bearing when the motors are fabricated in error. The prototype of the motor with the fluid dynamic bearing is manufactured, and experiment results show the vibration, sound, and phase current at no load and color wheel load of the motors in comparison. The high performance characteristics with the low vibration, the low acoustic noise and the optimal mechanical structure are verified by the experimental results.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2009년도 제40회 하계학술대회
• /
• pp.802_803
• /
• 2009

This paper deals with extraction of design parameters of Linear Switched Reluctance Motor (LSRM) and electromagnet based on force calculation using space harmonic analysis and 2D Finite Element Method (FEM) measurement. We introduce the design method employing FEM and parameter estimation method and a characteristics of LSRM according to variation of parameter.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2001년도 하계학술대회 논문집 B
• /
• pp.846-848
• /
• 2001

In this paper, electromagnetic fields of a linear induction motor with cage-type secondary are analyzed by the finite element method. Contact resistances between end-bars and secondary conductors are considered in the finite element analysis. The field quantify is a magnetic vector potential transformed into a phasor form. As a result, the sensitivities of a phase current thrust and normal force are presented according to the variation of the contact resistance.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2000년도 추계학술대회 논문집
• /
• pp.389-392
• /
• 2000

This paper presents a performance Analysis of electrically exhaust gas recirculation valve using commercial electromagnetic simulation software, Flux2D. Under the assumption of 2D axi-symmetric magnetic field, the characteristics of EEGR valve by revising the design parameter, has ken investigated by estimating the variation of thrust force with respect to the pintle position. The mode shapes and the frequency response functions were computed by using three dimensional finite element modeling of the whole EEGR valve and their accuracies were verified with experimental FFT analysis technique.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1989년도 추계학술대회 논문집 학회본부
• /
• pp.15-19
• /
• 1989

In this paper, the thrust force characteristic of SLIM according to the variation of several parameters was calculated from the fundamental equation based on Maxwell' s electromagnetic equation to design the transportation system which is drived by short primary single sided linear induction motor. The transportation system of moving secondary was constructed by the design values calculated on the base of simulated data and this values were compared to experimental values, and also the control method of transportation system was proposed.