• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제55권2호
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• pp.107-115
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• 2006

In this paper, a new speed sensorless control based on an instantaneous reactive power is proposed for the interior permanent magnet synchronous motor(IPMSM) drives. In proposed algorithm, the current observer estimates the line currents and the estimated speed can be yielded from the voltage equation because the information of speed is included in back EMF. To implement speed sensorless control, the current observer is composed by using the voltage equation of the IPMSM in the stationary reference frame fixed to the stator. The estimated speed of the rotor is composed by using the voltage equation of the IPMSM in the rotating reference frame fixed to the rotor The estimated speeds to minimize the speed error compensated by using the instantaneous reactive power. The instantaneous reactive power is calculated on the rotating reference frame fixed to the rotor. The effectiveness of the preposed algorithm is confirmed by the experiments.

• 대한임상검사과학회지
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• 제55권1호
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• pp.29-36
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• 2023

이 연구는 특수건강진단 폐활량검사 시 아시안 외국인 근로자들에게 적절한 예측식을 제안하는 것이다. 연구 대상은 지리적 분포에 따라 중앙아시아, 동북아시아, 남아시아태평양 그룹으로 나누었으며, 그룹별 폐활량검사 결과와 예측식간 일치도를 확인하였다. 이를 기준으로 국내 외국인 근로자들에게 폐활량검사 시 적절한 예측식을 제안하였고, 제안한 예측식을 적용할 수 없는 폐활량검사기에는 보정계수를 제안하였다. Global lung function initiative 2012 (GLI2012)-동북아시안식과 동남아시안식의 해석일치도는 남성 0.819, 여성 0.770이었고, GLI2012-동남아시안식과 남아시안식의 해석 일치도는 남성 0.881, 여성 0.886이었다. GLI2012-동북아시안식과 중앙아시안식의 해석일치도는 남성 0.831, 여성 0.833이었다. 따라서 동북아시안, 중앙아시안 그룹에 속하는 외국인 근로자는 GLI2012-동북아시안식을 적용하고, 동남아시안, 남아시안 그룹에 속하는 외국인 근로자는 GLI2012-동남아시안식을 제안한다. GLI2012-동남아시안식을 선택할 수 없는 폐활량검사기의 경우 최정근식(Dr. Choi equation)에 보정계수 0.87을 적용할 것을 제안한다.

• 한국수자원학회논문집
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• 제41권4호
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• pp.413-422
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• 2008

기상자료가 부족하거나 결측 지역의 기준 증발산량 산정을 위하여 Penman-Monteith (PM) 공식을 이용한 Hargreaves 공식의 매개변수 추정을 수행할 필요가 있다. 본 연구에서는 경기만 유역에 위치한 강화, 인천, 수원, 서산, 천안의 1997년$\sim$2004년 기상자료를 바탕으로 PM 공식을 이용하여 계산한 기준 증발산량(이하 ETo)을 이용하여 Hargreaves 공식의 매개변수를 추정하였으며, 추정된 매개변수를 이용하여 2005년$\sim$2006년의 PM 공식을 이용한 ETo 결과와 비교하여 검정을 수행하였다. 그 결과, 매개변수 조정 전 RMS 오차는 $14.63{\sim}23.30$ 정도로 파악되었으며, 모형의 검정에서도 $14.43{\sim}26.81$ 정도로 유사한 범위를 보이고 있다. 한편, Nash-Sutcliffe 일치계수는 $0.68{\sim}0.77$이며, 검정과정에서는 $0.43{\sim}0.85$로 대부분의 지역이 추정효율이 아주 떨어지는 것으로 나타났다. 반면, Hargreaves 계수를 조정한 경우, RMS 오차는 $5.23{\sim}11.75$ 정도로 파악되었으며, 모형의 검정에서도 $6.48{\sim}9.09$정도로 매개변수 조정전에 비하여 크게 감소하고 있음을 알 수 있으며, 한편, NSC는 $0.92{\sim}0.98$이며, 검정과정에서는 $0.93{\sim}0.97$로 대부분의 지역에서 추정효율이 크게 향상되는 것으로 나타났다.

• Kyungpook Mathematical Journal
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• 제46권3호
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• pp.329-336
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• 2006

In the category of the group theoretic methods using invertible discrete group transformation, we give a useful relation between Emden-Fowler equations and nonlinear heat equation. In this paper, by means of appropriate transformations of discrete group analysis, the nonlinear hate equation transformed into the class of the Emden-Fowler equations. This approach shows that, under the group action, the solution of reference equation can be transformed into the solution of the transformed equation.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2001년도 춘계학술대회 학술발표 논문집
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• pp.144-147
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• 2001

This paper presents adaptive fuzzy controller which is uncertainty or unknown variation in different parameters with nonlinear system of helicopter. The proposed adaptive fuzzy controller applied TSK(Takagi-Sugeno-Kang) fuzzy system which is not only low number of fuzzy rule, and a linear input-output equation with a constant term, but also can represent a large class of nonlinear system with good accuracy. The adaptive law was designed by using Lyapunov stability theory. The adaptive fuzzy controller is a model reference adaptive controller which can adjust the parameter $\theta$ so that the plant output tracks the reference model output. First of all, system of helicopter was considered as stopping state, and design of controller was simulated from dynamics equation with stopping state. Results show that it is controlled more successfully with a model reference adaptive controller than with a non-adaptive fuzzy controller when there is a modelling error between system and model or a continuous added noise in such unstable system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 B
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• pp.882-884
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• 2002

The transient voltage characteristics of capacitor self-exited induction generator are analyzed by the state equation which is obtained from the d-q axis equivalent circuit of stationary reference frame and torque equation. The d-q equivalent circuit is composed using the condition of stationary reference frame. The mutual inductance is only considered as a function of magnetizing current in the equivalent circuit. The characteristics are analyzed and discussed by the backward Euler method for various load conditions under specified initial conditions and input.

• 대한기계학회논문집A
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• 제25권4호
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• pp.619-628
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• 2001

A viscoelastic constitutive equation of rubber is proposed under small oscillatory load superimposed on large static deformation. The proposed model is derived through linearization of Simos nonlinear viscoelastic constitutive model and reference configuration transformation. Statically pre-deformed state is used as reference configuration. The model is extended to a generalized viscoelastic constitutive equation including widely-used Mormans model. Static deformation correction factor is introduced to consider the influence of pre-strain on the relaxation function. The model is tested for dynamic behavior of rubbers with different carbon black fractions. It is shown that the constitutive equation with static deformation correction factor agrees well with test results.

• Journal of Advanced Marine Engineering and Technology
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• 제16권4호
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• pp.50-59
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• 1992

The paper presents a digital speed control approach of induction motor systems by using a digital servo control method and a well-known second order differential equation as model. The basic concept of using the modeling equation stated in the above is induced from the control theory stand point such that we can describe usually the motor system connected by inverter, generator and load etc, just as a mechanical system to be controlled. The concept does not demand us the complicated vector-based modeling equation adopted in the traditional methods for the speed control of induction motor. Futhermore, the proposed speed control system can be treated as a single input and single output system. The effectiveness of the servo control system obtained by the above-mentioned design concept is illustrated by the experimental results in the presence of both step reference changes and load variations. It is observed from the experimental results that the steady state-error of the experimental set up becomes zero after some regulation time and the induction motor system is robust in spite of reference signal changes and load variations.

• Journal of Mechanical Science and Technology
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• 제14권2호
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• pp.168-176
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• 2000

Related to the error dynamics of an adaptive system, averaging theorems are developed for coupled differential equations which consist of ordinary differential equations and a parabolic partial differential equation. The results are then applied to the convergence analysis of the parameter estimate errors in the model reference adaptive control of a nonautonomous parabolic partial differential equation with lowly time-varying parameters.

• 수산해양기술연구
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• 제28권1호
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• pp.27-38
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• 1992

The paper presents a digital speed control approach of induction motor systems by using a digital redesign method and adopting a well known 2nd order model as the system model equation. The basic concept using the modeling equation is induced from the control theory stand point such that we can describe usually the motor system connected by inverter, generator and load etc. just as a mechanical system to be controlled. The concept does not demand us the complicated vector-based modeling equation adopted in the traditional methods for the speed control of induction motor. The effectiveness of the servo control system composed by the above mentioned design concept is illustrated by the experimental results in the presence of step reference change and generator load variation. It is observed from the experimental results that the steady state error of the experimental set up becomes zero after some regulation time and the induction motor system is robust in spite of reference signal change and load variation of generator.