• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.778-781
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• 2008

The aim of this paper is to analyze the dynamic responses of pantograph-overhead contact line coupled system by using a condition monitoring system. The monitoring items are strain, vertical displacement and acceleration of a contact wire. Both strain and vertical displacement in the contact wire depends on uplift force and train velocity. Measurement of acceleration shows that the passage of the pantograph gives an impact force to a hard point on a contact wire.

• Proceedings of the KSR Conference
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• 2000.11a
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• pp.170-177
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• 2000

The Main objective of the study is to find out the basic running condition of KNR EMUs since the results can be useful in designing new EMUs. We had investigated the average annual mileages and decrepit levels. After that, we performed stress analysis for the carbody when uniformly distributed vortical loads due to the weight of the car body and passengers were applied to the underframes, in order to find out the most critical sections of the underframes and the effect of corrosion on the underframe strength.. Upon performing stress analysis, we carried out running tests of EMUs on the conventional line to measure dynamic stresses applied to the underframes.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1937-1942
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• 2010

Vehicle dynamic behavior should be investigated to establish the track irregularity criteria because they have an impact on vehicle dynamic behavior. The tilting train which have been developed in Korea will be operated on the conventional line. Therefore, it should be checked that the track irregularity criteria of conventional line is still available for the new vehicle. In this paper, the influence of vertical alignment on running behavior and safety for tilting train was instigated by numerical analysis. The wavelength and amplitude of vertical alignment were considered in scenario of this numerical analysis. This research is based on just numerical analysis and the final result which include measurement will be published in the future.

• 한국전산유체공학회:학술대회논문집
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• 1999.11a
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• pp.85-94
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• 1999

Transient aerodynamic response of an airfoil to a moving plane-flap is numerically investigated using two-dimensional Euler equations with conservative Chimera grid method. A body moving relative to a stationary grid is treated by an overset grid bounded by a 'dynamic domain-dividing line' the concept of which is developed in this study. A conservative Chimera grid method with a dynamic domain-dividing line technique is applied and validated by solving the flowfield around circular cylinder moving supersonic speed. The unsteady and transient characteristics of the flow solver is also examined by computations of a oscillating airfoil and a ramp pitching airfoil respectively. The transient aerodynamic behavior of an airfoil with a moving plane-flap is analyzed for various flow conditions such as deflecting rate of flap and free stream Mach number.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.2 no.2
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• pp.75-83
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• 2003

Recently, the machine tools have been needed for high speed and accuracy to increase productivity. The most Important thing to get a more stabilized machine is to know the frequency response which has an effect on manufacture a lot. This problem should be considered seriously by many researchers. There are many application programs about FEM but Just using FEM program to get information of the object is not enough to put our confidence in the stability of the machine tool design. Therefore, the purpose of this research is to make a study for proving one of the ways to design to produce stabilized a machine more efficiently by comparing FRT method and FEM. At these two tests, we can learn about the frequency response area causing resonance and we can reconfirm the result to trust.

• Journal of Power Electronics
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• v.9 no.2
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• pp.188-197
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• 2009

This paper presents an adaptive flux observer to estimate stator flux linkage and stator inductances of an interior permanent-magnet synchronous machine considering magnetic saturation. The concept of static and dynamic inductances due to saturation is introduced in the machine model to describe the relationship between current and flux linkage and the relationship between their time derivatives. A flux observer designed in the stationary reference frame with constant inductance is analyzed in the rotor reference frame by a frequency-response characteristic. An adaptive algorithm for an on-line inductance estimation is proposed and a Lyapunov-based analysis is given to discuss its stability. The dynamic inductances are estimated by using Taylor approximation based on the static inductances estimated by the adaptive method. The simulation and experimental results show the feasibility and performance of the proposed technique.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.2B no.3
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• pp.90-94
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• 2002

The line start permanent magnet (LSPM) motor has been developed facilitate to the design of the synchronous motor. The rotor of this motor is composed of interior permanent magnets and aluminum bars instead of rotor windings. It is difficult to predict the performance characteristics accurately, because many characteristics are produced by the aluminum rotor bars and the permanent magnets. Therefore, in this paper the dynamic characteristics of the LSPM motor are described and compared via the time-stepped finite element method with those of the cage-type induction motor to find the characteristics of the permanent magnets and the rotor bars in the LSPM motor.

• Proceedings of the KIEE Conference
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• 1999.11b
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• pp.361-363
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• 1999

This paper proposes an SSSC based on 3-level half-bridge inverters. The dynamic characteristic of the proposed SSSC was analyzed by EMTP simulation, assuming that the SSSC is inserted in the transmission line of the one-machine-infinite-bus power system. The proposed SSSC has six 3-level half-bridge inverters per phase, which operates in PWM mode. The proposed SSSC generates a quasi-sinusoidal output voltage by 90 degree phase shift to the line current. The proposed SSSC does not require the coupling transformer for voltage injection, and has a flexibility in operation voltage by increasing the number of series connection.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.133-134
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• 2006

A cylindrical capacitive displacement sensor (CCS) was developed and applied for monitoring end milling processes. Dynamic characteristics of a spindle-assembly were measured using the CCS and a designed magnetic exciter. The technique to extract the spindle displacement component caused only by cutting from the measured signals using the CCS was proposed in the paper. Using CCS signals and FRF (Frequency Response Function) derived from dynamics of the spindle tool system, dynamic cutting forces are estimated quantitatively.

• Tribology and Lubricants
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• v.10 no.1
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• pp.35-45
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• 1994

The thermohydrodynamic analysis of tilting pad thrust bearing is studied with the consideration of elastic effect of pad. Reynolds equation, deflection equation and energy equation are solved simultaneously with the boundary conditions. Reynolds equation is modified as the approximate form. Pads are supported by the line pivot and the point pivot respectively. Pads are considered as the flat planes. Effects of pad thickness on the performance of thrust bearing are emphasized and the performances of rigid pad and elastic pad are compared. Effects of inlet temperature on performances of the bearing are compared. Dynamic characteristics of both pad supported by line and point pivot are compared.