• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.225-260
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• 2002

The purpose of this paper is to further extend the theoretical understanding of the dynamic end milling process and to derive a computational model to predict the milling force components. A comparative assessment of different cutting force models is performed to demonstrate that the instantaneous shear plane based formulation is physically sound and offers the best agreement with experimental results. The procedure for the calculation of the model parameters used in the cutting force model, based on experimental data, has been presented. The validity of the proposed computational model has been experimentally verified through a series of cutting tests.

• Journal of computational fluids engineering
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• v.5 no.1
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• pp.27-32
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• 2000

This study investigates the problem of phase change from liquid to solid in the inviscid stagnation flow. The instantaneous location of the solid-liquid interface is fixed for all times by a coordinate transformation. Finite difference method is used to obtain the solution of the unsteady problem, and the growth rate of solid and the transient heat transfer from the surfaces of solid are investigated. The transient solution is dependent on the three dimensionless parameters, but the final steady state is determined by only one parameter of temperature ratio/conductivity ratio. It is observed that the instantaneous heat flux at the surface of solid can be obtained with sufficient accuracy by measuring the thickness of the solid or vice versa.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.7 no.3
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• pp.421-434
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• 1995

A new instantaneous flowmeter for hydraulics by means or cylindrical chokes is developed. In this method the instantaneous flowrate through chokes is predicted in real time from measurement of pressure difference on both sides of cylindrical choke. The experimental study for the flowrate of pulsating flow in a pipe is carried out to measure differential pressure drop by using a strain gauge pressure transducer with data acquisition and processing system. A pulsating flow is verified by a visualization method. In the present study, the flow characteristic variables of laminar pulsating flow are investigated analytically and experimentally in a circular pipe. Characteristic parameters of ratio of inertia term to pressure term($\phi_{t.1}$) and ratio of viscous term to pressure term($\phi_{z.1}$) are introduced to describe the flow pattern of laminar pulsating flow.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1053-1055
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• 2000

This paper describes a new approach to estimating permanent magnet synchronous motor(PMSM) speed and position from measured terminal voltages and currents for speed-sensorless vector control. The proposed system is based on observing the instantaneous reactive power of the motor. The described technique is very simple and robust to variations of motor parameters. The new approach is not dependent upon the value of the stator resistance. Also, MRAS schemes are chosen for determining the adaptive law for the speed and the position estimator. The effectiveness is verified by simulation.

• Water for future
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• v.23 no.1
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• pp.89-98
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• 1990

This study is developed the runoff analysis method that is used the geomorphologic instantaneous unit hydrograph to the relative role of network geometry in a basin. The quantitative expressions for the geomorphologic characteristics of a basin are used Shreve's link sepration and width function method. The network geometry are used Weibull's distribution as probability model of the width function, the structural characteristics of channel networks and the other geomorphologic parameters for the gaged basin.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.348-351
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• 2001

In this paper, voltage-fed high frequency resonant inverter of instantaneous current phaser control method used to DC voltage source separated is proposed. In the output control method, a novel circuit type of phase shift driving signal method with CVCF illustrated, also the operation principle of the proposed circuit is described in detail and its characteristics are presented as to normalized parameters. According to the each mode, in order to the circuit analysis and characteristic evaluation of the state equation are derives and present used to normalized parameter. In the future, this proposed inverter show that it can be practically used as power source system for the lighting equipment of discharge lamp, DC-DC converter etc.

• Proceedings of the KIEE Conference
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• 2000.11b
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• pp.384-386
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• 2000

This paper describes a new approach to estimating permanent magnet synchronous motor(PMSM) speed and position from measured terminal voltages and currents for speed-sensorless vector control. The proposed system is based on observing the instantaneous reactive power of the motor. The described technique is very simple and robust to variations of motor parameters. The new approach is not dependent upon the value of the stator resistance. Also, MRAS schemes are chosen for determining the adaptive law for the speed and the position estimator. The effectiveness is verified by the experimental results.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.237-239
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• 1995

The inverter for UPS system is required to satisfy pure sinusoidal output voltage with very low THD(Total Harmonic distortion). This paper proposes a TMS320c31 digital signal processor based predictive instantaneous control scheme of inverter. The proposed scheme is able to satisfy the conditions; high capability, high efficiency, low audible noise and robustness of inverter. The transient state characteristics of proposed inverter has been improved. in case of power failure or recovery, nonlinear load, sudden load change or parameters variations. Finally, the performance of the proposed inverter is shown and discussed by simulation and experiment.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.1
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• pp.50-56
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• 1999

This paper presents consideration on validity of instantaneous correlation power theory. The proposed power theory is defined and analyzed by time domain approach, thus it is easy to understand and instrument. The power is decomposed into active, fundamental reactive and harmonics components based on the autocorrelation and crosscorrelation signal techniques between voltage and current waveforms. On the compensation property, active power filter deal with three components only. Also, for real time control of active power filter, the power models with difficult concept are not cost effective. To verify the validity of the instantaneous correlation power theory, experimental work for voltage type DSP based active power filter is achieved. The power of thyristor controlled motor drives is decomposed into three orthogonal components by proposed power theory. From compensation results, validity of proposed theory is confirmed. feedback controller needs the information on some motor parameters. New recursive adaptation algorithms for rotor resistance and mutual inductance which can be applied to our nonlinear feedback controller are also presented in this paper. The recursive adaptation algorithms make the estimated values of rotor resistance and mutual inductance track their real values. Some simulation and experimental results show that the adaptation algorithms are robust against the variation of stator resistance and stator inductance.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.52 no.4
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• pp.172-178
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• 2003

This paper examines the application of high voltage static var compensator(SVC) with cascade multilevel inverter which employs H-bridge inverter(HBI). This method has the primary advantage that the number of voltage levels can be increased for a given number of semiconductor devices when compared to the conventional control methods. The SVC system is modeled using the d-q transform which calculates the instantaneous reactive power. This model is used to design a controller and analyze the SVC system. From the mathematical model of the system, the design procedures of the circuit parameters L and C are presented in this thesis. To meet the specific total harmonic distortion(THD) and ripple factor of the capacitor voltage, the circuit parameters L and C are designed. Simulated and experimental results are also presented and discussed to validate the proposed schemes.