• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1993.06a
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• pp.1054-1057
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• 1993

A direct method of fuzzy inference and a fuzzy algorithm with learning function are applied to the steam generator level control of nuclear power plant. The fuzzy controller by use of direct inference can control the steam generator in the entire range of power level. There is a little long response time of fuzzy direct inference controller at low power level. The rule base of fuzzy controller with learning function is divided into two parts. One part of the rule base is provided to level control of steam generator at low power level (0%∼30% of full power). Response time of steam generator level control at low power level with this rule base is shown generator level control at low power level with this rule base is shown to be shorter than that of fuzzy controller with direct inference.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.3
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• pp.192-200
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• 2019

This paper is analyzed causality using cointegration test and impact response after deriving a causality between direct overseas purchasing and sale and macroeconomic variables. The model used for the empirical analysis is the vector error correlation model. The model is used the macroeconomic variables such as the consumer price index and the GDP, and e-commerce variables such as direct overseas purchasing, direct overseas sales and online shopping amount. According to empirical analysis, the direct overseas purchasing has the causality with the consumer price index, and GDP has the causality with direct overseas purchasing and online. According to the impact response analysis of the VECM, the direct overseas purchasing has a positive effect on the CPI and GDP, but the direct overseas sales has a negative effect on the CPI and GDP. In addition, both direct overseas purchasing and sales have a negative effect on online shopping, but it has been shown that the direct overseas purchasing has a bigger negative effect on online shopping.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.40 no.3
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• pp.199-207
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• 2003

This paper is proposed new fuzzy controller for high performance of interior permanent magnet synchronous motor(IPMSM) drive. New fuzzy controller take out appropriate amounts of accumulated control input according to fuzzily described situations in addition to the incremental control input calculated by conventional direct fuzzy controller The structures of the proposed controller is motivated by the problems of direct fuzzy controller. The direct controller generally give inevitable overshoot when one tries to reduce rise time of response especially when a system of order higher than one is under consideration. The undesirable characteristics of the direct fuzzy controller are caused by integrating operation of the controller, even though the Integrator itself is introduced to overcome steady state error in response. Proposed controller fuzzily clear out integrated quantities acrording to situation. This paper attempts to provide a thorough comparative insight into the behavior of IPMSM drive with direct and new fuzzy speed controller. The validity of new fuzzy speed controller is confirmed by response results for IPMSM drive system.

• 한국신재생에너지학회:학술대회논문집
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• 2008.10a
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• pp.286-289
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• 2008

Mass of generator is one of the most important characteristic value especially direct drive type wind turbine. This paper introduce how to decease mass of generator rotor frame without declining generator performance. To obtain optimal design of rotor frame, sensitivity analysis using Taguchi method and RSM(response surface method) are have been performed.

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.208-210
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• 2007

This paper proposes a novel direct instantaneous pressure control(DIPC) of hydraulic pump system with SR drive. And it has very simple control structure, because it doesn’t use any speed and torque control for adjusting pump pressure. The hysteresis band of pressure and proper switching rules can make the actual pump pressure to be constant with fast dynamic response. Therefore, the proposed DIPC method can control of hydraulic pump pressure steadily with fast dynamic response.

• Coupled systems mechanics
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• v.1 no.3
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• pp.235-245
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• 2012

The nonlinear resonant response of an axially moving beam is investigated in this paper via two different numerical techniques: the pseudo-arclength continuation technique and direct time integration. In particular, the response is examined for the system in the neighborhood of a three-to-one internal resonance between the first two modes as well as for the case where it is not. The equation of motion is reduced into a set of nonlinear ordinary differential equation via the Galerkin technique. This set is solved using the pseudo-arclength continuation technique and the results are confirmed through use of direct time integration. Vibration characteristics of the system are presented in the form of frequency-response curves, time histories, phase-plane diagrams, and fast Fourier transforms (FFTs).

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.252-255
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• 2001

In this paper, a mathematical model of permanent magnet synchronous motor (PMSM) fed by inverter with Direct Torque Control (DTC) Dynamic and steady state characteristics of PMSM is simulated and analyzed: electro-magnetic torque response, speed response, locus of the stator flux linkage. It is mathematically proven that the increase of electromagnetic torque in a permanent magnet motor is proportional the increase of the angle between the stator and rotor flux linkages, and, therefore, the fast torque response can be obtained by adjusting the rotating speed of the stator flux linkage as fast as possible. The simulation results verify the proposed control and also show that the torque response under DTC is much faster than the PWM current controlled drive.

• Structural Engineering and Mechanics
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• v.3 no.3
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• pp.273-287
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• 1995

Stochastic response of systems to random excitation can be estimated by direct integration methods in the time domain such as the stochastic central difference method (SCDM). In this paper, the SCDM is applied to compute the variance and covariance in response of linear and nonlinear structures subjected to random excitation. The accuracy of the SCDM is assessed using two-DOF systems with both deterministic and random material properties excited by white noise. For the former case, closed-form solutions can be obtained. Numerical results also are presented for a simply supported geometrically nonlinear beam. The stiffness of this beam is modeled as a random field, and the beam is idealized by the stochastic finite element method. A perturbation technique is applied to formulate the equations of motion of the system, and the dynamic structural response statistics are obtained in a time domain analysis. The effect of variations in structural parameters and the numerical stability of the SCDM also are examined.

• Proceedings of the Korea Society of Design Studies Conference
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• 2003.11a
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• pp.12-13
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• 2003

• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.310-313
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• 2003

This paper is proposed new fuzzy controller for high performance of interior permanent magnet synchronous motor (IPMSM) drive New fuzzy controller take out appropriate amounts of accumulated control input according to fuzzy described situations in addition to the incremental control input calculated by conventional direct fuzzy controller. The structures of the proposed controller is motivated by the problems of direct fuzzy controller. The direct controller generally give inevitable overshoot when one tries to reduce rise time of response especially when a system of order higher than one is under consideration. The undesirable characteristics of the direct fuzzy controller are caused by integrating operation of the controller, even though the integrator itself is introduced to overcome steady state error in response. Proposed controller fuzzy clear out integrated quantities according to situation. This paper attempts to provide a thorough comparative insight into the behavior of IPMSM drive with direct and new fuzzy speed controller. The validity of the comparative results is confirmed by simulation results for IPMSM drive system.