• 드라이브 ㆍ 컨트롤
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• 제14권4호
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• pp.23-28
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• 2017

Time-delay control with internal model (TDCIM) is the controller for robot manipulators that applies the time-delay estimation and the concept of internal model control (IMC). TDCIM is robust against unknown dynamics and non-linear friction like coulomb friction and static friction. It is simple and computationally efficient. This study presents the relationship between the discrete TDCIM and the discrete PID controller. The PID controller is the most popular control law in the real application. But often the PID controller can be difficult to achieve the desired level of control performance. The result in this study provides a good candidate solution to these situations.

• 산경연구논집
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• 제10권12호
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• pp.35-42
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• 2019

Purpose : This study examines The impact of human resource investment in internal control on stock price crash risk. Effective internal control ensures that information provided is complete and accurate, financial statements are reliable. By overseeing management, internal control systems can reduce agency costs between management and outside parties. In Korea, firms have to disclose information about internal control systems. The working experience of human resources in internal control systems is also provided for interested parties. If a firm hires more experienced internal control personnel, it can better facilitate the disclosure of information. Prior studies reported that information asymmetry between managers and investors increases future stock price crash risk. Therefore, the longer working experience internal control personnel have, the lower probability stock crashes have. Research design, data and methodology : This study analyzed the association between the working experience of internal control personnel and crash risk using regression analysis on KOSPI listed companies for fiscal years 2016 through 2017. The sample consists of 1,034 firm-years of non-financial firms whose fiscal year end on December 31. Career spanning data of internal control personnel was collected from internal control reports. The professionalism(IC_EXP) was measured as the logarithm of the average working experience of internal control personnel in months. Negative conditional skewness(NSKEW) and down-to-up volatility (DUVOL) are used to measure firm-specific crash risk. Both measures are based on firm-specific weekly returns derived from the expanded market model. Results : We find that work experience in internal control environment is negatively related to stock price crashes. Specifically, skewness(NSKEW) and volatility (DUVOL) are reduced when firms have longer tenure of human resources in internal control division. The results imply that firms with experienced internal control personnel are less likely to experience stock price crashes. Conclusions : Stock price crashes occur when investors realize that stock prices have been inflated due to information asymmetry. There is a learning effect when internal control processes are done repetitively. Thus, firms with more experienced internal control personnel could manage their internal control more effectively. The results of this study suggest that firms could decrease information asymmetry by investing in human resources for their internal control system.

• 전기학회논문지P
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• 제51권4호
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• pp.175-185
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• 2002

In this paper, a new fully digital current control method of UPS inverter, which is based on an internal model control, is proposed. In the proposed control system, overshoots and oscillations due to the computation time-delay are compensated by explicit incorporation of the time-delay in the current control loop transfer function. The internal model controller is adopted to a second order deadbeat reference-to-output response which means that its response reaches the reference in two sampling time including computational time-delays. That is, the average current of filter capacitor is been exactly equal to the reference current with a time lag of two sampling intervals. Therefore, this method has an essentially overshoot free reference-to-output response with a minimum possible rise time. The effectiveness of the proposed control system has been verified by the simulation and experimental respectively. From the simulation and experimental results, the proposed system is achieved the robust characteristics to the calculation time delay and parameter variation as well as very fast dynamic performance, thus it can be effectively applied to the power supply for the critical load.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년 학술대회 논문집 정보 및 제어부문
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• pp.108-110
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• 2006

This paper deals with a tracking problem for nonlinear systems using its T-S fuzzy model and internal model. We extend the internal model of linear systems to an internal model of T-S fuzzy systems to accompany with state error of zero. A sufficient condition of the existence of a tracking controller for T-S fuzzy systems is expressed by linear matrix inequalities. A system of inverted pendulum on cart is illustrated to verify our method.

• 디지털융복합연구
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• 제19권2호
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• pp.51-60
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• 2021

본 연구에서는 기업 내부통제의 중요성을 토대로 내부통제 품질과 이익조정과의 상관관계 분석을 바탕으로 내부통제 품질과 실제 이익 관리와 이익조정과의 상관관계를 분석하였다. 본 연구을 위해 내부통제 및 이익조정의 개념, 분류, 측정 방법 및 모델을 도입하여 본 논문의 연구가설을 제안하였다. 연구분석에서는 관련 측정 모델을 사용하여 기업의 실제 이익관리 수준과 이익조정 관리 수준을 설명 변수로 투입하여 회귀 모델을 설정하고 분석을 진행하였다. 연구결과, 실증 기업의 내부통제 품질, 실질적인 이익과 이익조정 간에는 통계적으로 유의미한 음의 상관관계가 있음을 확인하였으며, 실증 연구를 통해 최종 결과와 결론을 도출할 수 있었다. 이러한 연구결과는, 향후 내부통제 이론의 발전과 더불어 경영자의 이익조정 행동에 대한 관리 및 통제를 위한 기초적 가이드라인을 제공할 수 있을 것이다.

• International Journal of Computer Science & Network Security
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• 제21권1호
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• pp.64-69
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• 2021

In this paper, we have proposed a new internal model control structure (IMC). It is aimed at unstable overactuated multivariable systems whose transfer matrices are singular and unstable. The model inversion problem is essential to understand this structure. Indeed, the precision between the output of the process and the setpoint is linked to the quality of the inversion. This property is preserved in the presence of an additive disturbance at the output. This inversion approach proposed in this article can be applied to multivariable systems with no minimum phase or minimum phase shift with or without delays in their transfer matrices. It is proven by an example of simulation through which we have shown its good performance as a guarantee of stability, precision as well as rapidity of system responses despite the presence of external disturbances and we have tested this control structure in the frequency domain hence the robustness of the IMC.

• 디지털융복합연구
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• 제15권2호
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• pp.121-133
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• 2017

본 연구는 취약한 내부통제시스템을 형성하고 있을 가능성이 높은 기업들을 예측하는 적합한 모형을 형성하고, 이를 기반으로 취약기업의 특성을 살펴보고자 했다. 분석에 사용된 자료는 K_금융기관과 대출거래가 이루어졌던 상장법인과 비상장법인을 대상으로 하였다. 주요 결과로, 금융기관이 내부통제가 취약한 기업을 예측하기 위해서는 로짓모형에 비해 판별모형이 적합하다는 결론에 도달했다. 판별모형이 내부통제 취약기업을 취약기업으로 예측하는 정확도가 높고, 취약기업을 정상기업으로 잘못분류 할 오류가 낮았기 때문이다. 내부통제가 취약한 기업의 주요특성은 낮은 신용도, 낮은 자산건전성, 높은 연체율, 낮은 영업활동현금흐름, 높은 부채비율, 그리고 부(-)의 매출액영업이익률을 형성하는 기업으로 나타났다. 본 내부통제 취약예측모형을 포함한 연구결과는 자료구성의 한계로 연구가 이루어지지 않았던 비상장기업군까지 확장하였기에, 금융기관이 내부통제 취약가능성이 높은 기업을 사전적으로 예측하여 자산손실을 예방하는 도구로 이용할 수 있을 것이다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년 학술대회 논문집 정보 및 제어부문
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• pp.285-287
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• 2006

The paper treats the nonlinear robust control of Chua's circuit having Chuar's diode as an element based on the internal model principle. The Chua's diode has unknown nonlinear parameters and the circuits parameters are alos assumend unknown. Nonlinear regulator equations are established to obtain 3-fold equilibrium equations on which the output error is zero. Also an internal model of the 3-fold exosystem is constructed for obtaining the control law. Pole Placement method is used for obtaining the feeback control law. Simulation results are presented for tracking the sinusoidal and constant reference input signal. Asymptotic trajectory control and the suppression of chaotic motion in spite of uncertainties in the system are accomplished.

• 제어로봇시스템학회논문지
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• 제7권11호
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• pp.958-961
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• 2001

Control of Industrial processes is very difficult due to nonlinear dynamics, effect of disturbances and modeling errors. M.Morari proposed Internal Model Control(IMC) system that can be effectively applied to the systems with model uncertainties and time delays. The advantage of IMC is their robustness with respect to a model mismatch and disturbances. But it is difficult to apply for nonlinear systems. ANFIS(Adaptive Neuro-Fuzzy Inference System) which contains multiple linear models as consequent part is used to model nonlinear systems. Generally, the linear parameters in ANFIS can be effectively utilized to control a nonlinear systems. In this paper, we propose new ANFIS-based IMC controller for nonlinear systems. Numerical simulation results show that the proposed control scheme has good performances.

• 대한전기학회논문지:전력기술부문A
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• 제48권2호
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• pp.159-167
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• 1999

A digital tracking controller is proposed for a precise positioning control under a large repetitive and/or non repetitive disturbances. The proposed control system. Numerical Examples are illustrated for a precise head positioning of optical disk drives regardless of a torque disturbance and/or output disturbance.