• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.64.6-64
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• 2002

This paper presents a procedure of implementing a robust controller for a paper-making plant in DCSs. A paper-making process generally has triple problems to automatically tune its output qualities : Long transport delays which are not able to be simply linearized. The transfer matrix of the process is not square. And every plant model has some uncertainty in low and middle frequency region. To tackle these problems, a multi-input / multi-output (MIMO) plant model having some uncertainty was derived by considering some physical and mechanical principles of the process. Then a MIMO robust \ulcornercontroller is designed and implemented in a real DCS as function block type. Som...

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.6
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• pp.187-194
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• 2005

The objective of this study is to validate the hybrid breakup model and the vaporization model for GDI spray analysis at vaporization and non-vaporization conditions. The atomization process is modeled by using hybrid breakup model that is composed of Linearized Instability Sheet Atomization (LISA) model and Aerodynamically Progressed Taylor Analogy Breakup (APTAB) model. The vaporization process is modeled by using modified Abramzon & Sirignano model. The exciplex fluorescence method was used for comparing the calculated results with the experimental ones. The experiment and the calculation were performed at the ambient pressures of 0.1 MPa, 0.5 MPa and 1.0 MPa and the ambient temperature of 293K and 473K.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.1
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• pp.6-13
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• 2002

This paper deals with the linear matrix inequality (LMI) design procedures for multi-objective Η$_2$/Η$_{\infty}$ controllers with pole-placement constraints for an inverted pendulum system modeled as convex polytopes to ensure the stabilizing regulator and tracking performances. Polytopic models with multiple linear time-invariant models linearized at some operating points are derived to design controllers overcoming the conservativeness such as a controller may have when it is designed for a model linearized at a single operating point. Multi-objective controllers are designed for polytopic models by the LMT design technique with convex algorithms. It is observed that the inverted pendulum controlled by any controller designed for each polytopic model is stabilizingly restored to the vertical angle position for initial values of larger tilt anlges.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.466-471
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• 2003

The purpose of this study is to obtain the accurate prediction for the atomization and vaporization processes of GDI spray. Atomization process is modeled using hybrid model that is composed of Linearized Instability Sheet Atomization (LISA) model and Aerodynamically Progressed TAB (APTAB) model. Vaporization process is modeled using Spalding model and Abramzon & Sirignano model. To obtain the experimental results for comparing with calculated results, the cross-sectional images of liquid and vapor phases and SMD distribution were acquired by exciplex fluorescence method and Phase Doppler Analyzer respectively. The experiment and computation was performed at the ambient pressure of 0.1 MPa, 0.5 MPa, 1.0 MPa and the ambient temperature of 293K, 473K. The calculated results by modified KIVA-II code show good agreement with experimental results.

• Coupled systems mechanics
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• v.7 no.2
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• pp.141-162
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• 2018

This work presents a novel model for analysis of the loading rate influence onto structure response. The model is based on the principles of nonlinear system dynamics, i.e., consists of a system of nonlinear differential equations. In contrast to classical linearized models, this one comprises mass and loading as integral parts of the model. Application of the Kelvin and the Maxwell material models relates the novel formulation to the existing material formulations. All the analysis is performed on a proprietary computer program based on Wolfram Mathematica. This work can be considered as an extended proof of concept for the application of the nonlinear solid model in material response to dynamic loading.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.5
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• pp.545-552
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• 2004

The purpose of this study is to improve the prediction ability of the atomization and vaporization processes of GDI spray. Several models have been introduced and compared. The atomization process was modeled using hybrid breakup model that is composed of Linearized Instability Sheet Atomization (LISA) model and Aerodynamically Progressed TAB (APTAB) model. The vaporization process was modeled using Spalding model and Abramzon ＆ Sirignano model. Exciplex fluorescence method was used for comparing calculated with experimental results. The experiment and computation were performed at the ambient pressure of 0.1 MPa, 0.5 MPa and 1.0 MPa and the ambient temperature of 293k and 473k. Comparison of calculated and experimental spray characteristics was carried out and the calculated results of GDI spray showed good agreement with experimental results.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.5
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• pp.550-556
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• 2014

In this study, for the control of a single water tank system, a fuzzy-PID controller design technique based on a fuzzy model is investigated. For this purpose, a water tank system is linearized as a number of submodels depending on the operating point, and a fuzzy model is obtained by fuzzy combining. Each submodel is approximated as a first order time delay model, and a PID controller is designed using several existing tuning techniques. Then, through the fuzzy combination of this controller using the same method as that of the fuzzy model, a fuzzy-PID controller is designed. For the proposed technique, a simulation is performed using the fuzzy model of a water tank system, and the validity is examined by comparing its performance with that of a PID controller.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.969-974
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• 2004

For a maneuvering unmanned autonomous helicopter, it is necessary to design a proper controller of each flight mode. In this paper, overall helicopter dynamics is derived and hovering model is linearized and transformed into a state equation form. However, since it is difficult to obtain parameters of stability derivatives in the state equation directly, a linear control model is derived by time-domain parametric system identification method with real flight data of the model helicopter. Then, two different controllers - a linear feedback controller with proportional gains and a robust controller - are designed and their performance is compared. Both proposed controllers show outstanding results by computer simulation. These validated controllers can be used to autonomous flight controller of a real unmanned model helicopter.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2004.04a
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• pp.117-126
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• 2004

This paper presents a linear model for heat transfer processes in the drying cylinders and the web in papar mill. The PDE model, functions include steam temperatures, wet temperatures, moisture constents, reel speed and basis weight were derived from operation data. The changes of wet temperatures and moisture contents in the drying cylinders and wets could be described. The Transfer function can be obtained through the state space model derived from the linearized PDE model. Stability of the drying cylinder model for paper plants and analysis of characteristics of process responses for changes in input variables are investigated.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.5
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• pp.364-370
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• 2000

A large-signal average model for the controlled on-time boost power factor correction(PFC) circuit is developed and subsequently linearized resulting in a small-signal model for the PFC circuit. Ac analyses are performed using the small-signal model, revealing new results new on small-signal dynamics of the PFC circuit. The analysis results and model predictions are confirmed with experimental measurements on 200W prototype PFC circuit.