• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2004년도 춘계학술대회 논문집
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• pp.64-69
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• 2004

The work presented here deals with controller design using error model constructed with proportional control ramp response. The design aims at the improvement of transient response, steady-state error reduction with stability preservation, generation of the consistent contour error through the proportional gain regulation of a mismatched system. The first step is to generate tracking-error curve with proportional control only and decide the added error signal shape on the error curve. The next is to construct a table for the steady-state loop gain with step input. The table is used for selecting the proportional gain. The effectiveness of the proposed controller is confirmed through the simulation and experiment.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 춘계학술대회논문집
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• pp.278-282
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• 2003

There is a strong industrial demands for the development of light-vehicle to improve fuel efficiency. It is more effective to reduce weight of the parts directly driven by an automobile engine. So the saving in weight of wheels which is operated by an automobile engine improve fuel efficiency more than other parts. There are many step of sheet metal forming in fabricating automotive wheel, so that it is difficult to design process and tools of multi-stage stamping. Traditionally, design process and tools have depended on the experience of skilled workers and it has done by trial and error methods. However, it needs too much costs and time. Taguchi methods has an advantage of the number of required experiments and reliability compared with trial and error method. In this study, Taguchi methods and response surface methods are applied to design process and tools of automotive wheel. As a result, the principal variables are selected and process conditions are optimized.

• 오토저널
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• 제15권1호
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• pp.67-72
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• 1993

Wall wetting phenomenon in the intake port of an MPI engine was investigated with different kinds of injectors by an A/F step response test and analysis was done based on the simple wall wetting model to find out a certain correlation between wall wetting and A/F variations. It was found that (1) At fully warmed condition of 90.deg.C water temperature, around 40-60% of injected fuel was wall wetted, (2) At cold condition of 45.deg.C Water temperature, around 68-80% of injected fuel was wall wetted, and (3) A/F variations during acceleration and deceleration were influenced by the wetting area, the fuel droplet size, and the amount of wall wetting fuel.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 B
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• pp.653-656
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• 2001

This paper describes the design and the analysis of permanent magnetic actuator "Magnetic Switch" using classical method and 2D finite element method. The classical method gives an outline of permanent magnet size and analysis is carried out by finite element method. Therefore we make use of the result in specific detail site of magnet. The transient state is simulated in order to calculate the response time of "Magnetic Switch". The simulation is based upon a step-by-step integration of the electric circuit equations and the tore movement. The contactor uses a permanent magnet for maintaining the closed state. The presented solution takes account of non-linear magnetic material property and spring force controlled by core position. The dynamic response of "Magnetic Switch" is predicted by the simulation agrees closely with the required condition.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.1120-1123
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• 1996

DMC(Dynamic Matrix Control) algorithm has been successfully used in industries for more than a decade. It can handle constraints and easily extended to MIMO case. The application of DMC, however, is limited to the open loop stable process because it uses the FIR(Finite Impulse Response) or FSR(Finite Step Response) model. Integrating process widely used in chemical process industry, is the representative open loop unstable process. The disturbance rejection of DMC is relatively poor due to the assumption that the current disturbance is equivalent to the future disturbance. We propose the IDMC(Improved Dynamic Matrix Control) for the integrating process, as well as non-integrating process. IDMC has shown better disturbance rejection using multi-step ahead predictor for the disturbance.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.175-178
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• 2000

An aerostatic stage has frictionless behavior, so it has a advantage of investigation into positioning characteristics. A one-dimensional aemstatic ceramic stage with ballscrew driven and laser scale feedback system is manufactured. aiming at investigating positioning characteristic of aerostatic stage, especially position error and repeatability, we analyze positioning behavior with other factors such as angular error, temperature. Experimemal results show that the aerostatic stage has a l0nm micro step response. Comparing experimental results and calculated abbe's error, we confirm that mean of position error is owing to angular error. And, also we confirm the temperature is dominant factor of repeatability in ten nm order.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 춘계학술대회 논문집
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• pp.610-614
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• 1996

As the run out error and misalignment of ball screw connected directly to guide table largely affect the motion accuracy of guideway, floating coupling that releases the table from screw nut except feed and rotational direction is needed todecrease its influences. The purpose of this study is to propose a practical model floating coupling of ball serew for high precision feeding system. The straightness, dynanic characteristics and micro step response of hydrostatic guideway, mounted with three types of coupling fixed type, leaf spring type and hydrostatic type, are tested and compared. From the resuts of experiments, it is proved that a hydrostatic type floating coupling is superior to other couplings and is available to high precision feeding system with ball screw.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제50권4호
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• pp.151-157
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• 2001

This paper presents an identification method of parameters of induction motor which is driven by PWM voltage inverter. The method uses least square estimation based on the step voltage input and current response. Utilizing the fact that ratio of two characteristic roots is large in the induction motor circuit, we derived two 1st-order difference equations for direct computation of parameter values. experimental results are compared with conventional motor test results to demonstrate that the proposed method is capable of estimating parameters of induction motor at standstill.

• Journal of Mechanical Science and Technology
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• 제17권7호
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• pp.966-977
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• 2003

This paper investigates how intentional mistuning of bladed disks reduces their sensitivity to unintentional random mistuning. The class of intentionally mistuned disks considered here is limited, for cost reasons, to arrangements of two types of blades (A and B, say). A two-step procedure is then described to optimize the arrangement of these blades around the disk to reduce the effects of unintentional random mistuning. First, a pure optimization effort is undertaken to obtain the pattern (s) of the A and B blades that yields small/the smallest value of the largest amplitude of response to a given excitation in the absence of unintentional random mistuning using Genetic Algorithm. Then, in the second step, a qualitative/quantitative estimate of the sensitivity for the optimized intentionally mistuned bladed disks with respect to unintentional random mistuning is performed by analyzing their amplification factor, probability density function and passband/stopband structures. Examples of application with simple bladed disk models demonstrate the significant benefits of using this class of intentionally mistuned disks.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1999년도 제14차 학술회의논문집
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• pp.116-120
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• 1999

The step response of the Manabe standard form[1］has little overshoot and shows almost same waveforms regardless of the order of the characteristic polynomials. In some situations it is difficult to control the rise time and settling time simultaneously of the step response of the Manabe standard form. To control its rise time and settling time efficiently, we develop the generalization of the Manabe standard form: we try to find out the SRFS(Slow Rise time & Fast Settling time) form which has the slower rise time and faster settling time than those of the Manabe standard form. we also consider the other three forms: FRSS(Fast Rise time & Slow Settling time), SRFS(Slow Rise time ＆ Fast Settling time) and SRSS(Slow Rise time & Slow Settling time) forms. In this paper, by using the genetic algorithm, we obtain all the coefficient of the four forms we mention above. Finally, we design a controller for a given plant so that the overall system has the performance that the rise time is faster, the settling time is slower than those of the Manabe standard form.