• Journal of ILASS-Korea
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• v.25 no.2
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• pp.45-50
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• 2020

Recently, global warming and environmental pollution are becoming more important, and fuel economy is becoming important. Each automobile company is actively developing various new technologies to increase fuel efficiency. CVVD(Continuously Variable Valve Duration) system means a device that continuously changes the rotational speed of the camshaft to change the valve duration according to the state of the engine. In this paper, VVT(Variable Valve Timing) and CVVD were applied to a single-cylinder diesel engine, and the characteristics of intake and exhaust flow rate and in-cylinder pressure characteristics were analyzed by numerical analysis. In order to analyze the effect of CVVD on the actual engine operation, the study was performed by setting the valve control and injection pressure as variables in two sections of the engine operating region. As a result, In the case of applying CVVD, the positive overlap with the exhaust valve is maintained, thus it is possible to secure the flow smoothness of air and increase the volumetric efficiency by improving the flow rate. The section 2 condition showed the highest peak pressure, but the pressure rise rate was similar to that of the VVT 20 and CVCD 20 conditions up to 40 bar due to the occurrence of ignition delay.

• Journal of Drive and Control
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• v.18 no.4
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• pp.52-58
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• 2021

The variable structure controller is designed such that in sliding mode, the system moves along the switching plane in the vicinity of the switching plane, thus it is robust because it is not affected by the parameter fluctuations of the plant. However, a controller based on a variable structure may not meet the desired performance when it is commanded to track any input or is exposed to disturbances. This study proposes a sliding mode controller that follows the IVSC (Integral Variable Structure Control) approach with ELO (Extended Luenberger observer) to solve this problem. The proposed sliding mode control is applied to the velocity control of the hydraulic motor. The sliding plane was determined by the pole placement, and the control input was designed to ensure the existence of the sliding mode. The feasibility of modeling and controller are reviewed by comparing with conventional proportional-integral control through computer simulation using MATLAB software and experimenting on the cases of significant plant parameter fluctuations and disturbances.

• Proceedings of the KIEE Conference
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• 1986.07a
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• pp.140-144
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• 1986

In this paper an FIR(finite impulse response) filter and smoother are introduced for discrete time-invariant state-space models with driving noises. The FIR structure not only quarantees the BIBO stability and the robustness to parameter changes but also improves the filter divergence problem. It is shown that the impulse responses of the FIR filter and the smoother are obtained by Riccati-type difference equations and that they are to be time-invariant and reduced to very simple forms. For implementational purpose, recursive forms of the FIR filler and smoother are derived with each other used as the adjoint variable.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.460_461
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• 2009

This paper analyzes the steady state characteristics for variable speed wind power system with doubly-fed induction generator(DFIG). This paper explains the equivalent circuit and phasor diagram of DFIG for different operating conditions. It also simulates the torque-slip characteristics with respect to changes of different parameters. Simulation results show the torque-slip characteristics, stator power factor-rotor voltage and stator current-rotor voltage.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.1188-1193
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• 1993

For the HST(Hydrostatic Transmission) consisted of a variable displacement axial piston pump and motor, a speed controller with efficiencies considered is proposed. To consider a efficiency in speed control, the displacements of pump and motor which maximize a steady state efficiencies with a various load torque are calculated through computer simulation and these results are reflected to speed controller which has PI control structure with cross over control scheme. It is shown through computer simulation that the proposed controller gives better steady state efficiencies compared with the conventional controller and good transient responses.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.8
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• pp.899-905
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• 1988

In this paper, we suggest a new quasi-sliding mode condition with a wighting factor which guarantees all the states to reach switching planes and improves the convergence of the state trajectories. The result of computer simulation shows that by the suitable selection of a weighting factor, all the state trajectories reach switching planes and enter the sliding mode having the property of the insensitivity to parameter variation and disturbances.

• Journal of the Korean Data and Information Science Society
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• v.22 no.5
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• pp.967-976
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• 2011

The Box-Cox transformation is a well known family of power transformations that brings a set of data into agreement with the normality assumption of the residuals and hence the response variable of a postulated model in regression analysis. Normalization (studentization) of the regressors is a common practice in analyzing microarray data. Here, we implement Box-Cox transformation in normalizing regressors in microarray data. Pridictabilty of the model can be improved using data transformation compared to studentization.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.4
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• pp.7-13
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• 1998

The gloval model is developed by combining this actuator formular with robot manipulator which is reported previously . The model initially represented in the form of coupled time-varying nonlinear dynamic system. It then decomposed into the decoupled linear model using nonlinear feedback and state transformation techniques. The new model employes the pole replacement method to improve the stability of the system. Using this new model, an robust control algorithm is developed. The proposed algorithm takes two state variables, position vector and velocity vector, and one input variable from actuator, input voltage.

• Journal of the Korean Operations Research and Management Science Society
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• v.4 no.1
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• pp.41-51
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• 1979

The Classical multi-server heterogeneous queuing system can be more generalized by using the concept of the switching rules. The descriptions of these systems, the relations among the state probebilities at the various points of interest, and comparisons with the single-server system will be presented. Instead of using the imbedded markov chain we set up the simultaneous equations for the state probabilites by the supplementary variable method.

• 전기의세계
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• v.21 no.6
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• pp.9-16
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• 1972

This work intends to study the machine dynamics in the state-space approah and to formulate the operating characteristics of a namplidyne generator, with balanced control field winding and an auxiliary feedback winding for compensating purpose. In the derivation of the dynamic equation, investigations on the demagnetization effects are accentuated, based on the magnetic interlinks between windings of the machine. From the machine dynamic relation obtained, a state-variable representation of the machine dynamics is approached in the first part of this work.