• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.1792-1795
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• 1997

It is difficulte to control in the flow system because there are many disturbance. So it is impossible to control delicately sometimes by PI or PID. In this paper, we study on the application of intellignet control algorithms such as 2DOF PID control, neural network, Fuzzy contro, Relay feedback to the flow control system. the resultings are 2DOF-PID control is more good response.

• 대한전자공학회논문지
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• 제24권2호
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• pp.347-354
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• 1987

Timing simulators are widely used nowadays for analyzing large-scale MOS digital circuits, which, however, have several limitations such as nonconvergence and/or in accuracy for circuits containing tightly coupled feedback elements or loops. This paper describes a new timing simulator which aims at solving these problems. The algorithm employed is based on the wave-form relaxation method, but exploits the signal flow along the feedback loops. Each of feedback loops is treated as one circuit block and then local iterations are performed to enhance the timing simulation. With these techniques, out simulator can analyze the MOS digital circuits with up to 5-20 times of the magnitude speed improvemnets as compared to SPICE2, while maintaining the accuracy.

• 정보처리학회논문지:소프트웨어 및 데이터공학
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• 제8권8호
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• pp.317-322
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• 2019

프로그래밍 훈련 지원을 위한 프로그래밍 채점시스템은 일반적으로 웹 상에 구축되어 출제자는 프로그래밍 문제를 업로드하고 이를 학습자가 열람하고 문제에 대한 답안을 제출한다. 프로그래밍 채점시스템은 제출된 답안 소스코드를 실행하여 통과, 실패, 에러 메시지 등의 피드백을 제공한다. 통과를 제외한 피드백을 받은 학습자는 통과 판정받을 때까지 계속해서 소스코드를 디버깅한다. 본교에서 프로그래밍 훈련 지원을 위해 온라인 채점시스템을 자체 개발하였고 학생들이 제출한 답안을 분석한 결과 통과 판정을 받지 못한 학생들 중 다수가 자신이 틀린 부분을 정확하게 모른 채 계속해서 문제를 푼다는 사실을 확인하였다. 현재 프로그래밍 채점시스템은 주로 런타임 에러 메시지 위주로 피드백을 수행한다. 하지만 이러한 정보만으로는 프로그래밍 훈련을 하는 학습자들은 제출한 답안의 틀린 부분을 찾아내기가 어렵다. 따라서 본 논문에서는 학습자가 제출한 소스코드에 사용된 테스트케이스의 제어흐름을 분석한 결과를 프로그래밍 실패에 대한 피드백으로 제공하는 시스템을 제안한다. 제안한 시스템은 제어흐름 상의 결함이 존재할 수 있는 경로를 피드백하여 학습자들이 틀린 부분을 보다 빠르게 찾을 수 있게 도와준다. 또한 실제 학습자가 제출한 답안 소스코드를 예로 들어 본 시스템이 적용 가능함을 보인다.

• 대한수학회지
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• 제34권4호
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• pp.841-857
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• 1997

We present analysis and some computational methods for boundary optimal and feedback control problems for Navier-Stokes equations. We use one example to illustrate our methodology and ideas which are applicable to general control problems for Navier-Stokes equations. First, we discuss the existence of optimal solutions and derive an optimality system of equations from which an optimal solution may be computed. Then we present a gradient type iterative method. Finally, we present some numerical results.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.327-330
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• 2004

Laser aided direct metal deposition (LADMD) process offers the ability to make a metal component directly from 3-D CAD dimensions. A 3-D object can be formed by repeating laser cladding layer by layer. The key of the build-up mechanism is the effective control of powder delivery and laser power to be irradiated into the melt-pool. A feedback control system using optical sensors is introduced to control laser power and powder mass flow rate. Using H13 tool steel and $CO_2$ laser system, comprehensive analysis are executed to test the efficiency of the system. In addition, the dimensional characteristics of directed deposited material are investigated with the parameters of deposition thickness, laser power, traverse speed and powder mass flow rate.

• 한국산업융합학회 논문집
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• 제19권3호
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• pp.160-166
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• 2016

This study proposes the development and performance evaluation of electronic proportional control valve having an LVDT. The electronic proportional control valve is composed of hydraulic valve, proportional solenoid and controller. LVDT is to reduce the steady state error for the reference input of the controller by the feedback signal to detect the displacement of the spool. Designed LVDT is applied to the common proportional valve. In order to evaluate the performance of the developed valve, the hydraulic test equipment was developed and flow tests were carried out. From experimental results, it was proved that the hysteresis was less than 1% based on the maximum flow rate.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 12th Asian Congress of Fluid Mechanics
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• pp.46.5-47
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• 2008

• Journal of Mechanical Science and Technology
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• 제16권12호
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• pp.1561-1575
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• 2002

A reduced-order linear feedback controller, which is used to control the linear disturbance in two-dimensional plane Poiseuille flow, is applied to a boundary layer flow for stability control. Using model reduction and linear-quadratic-Gaussian/loop-transfer-recovery control synthesis, a distributed controller is designed from the linearized two-dimensional Navier-Stokes equations. This reduced-order controller, requiring only the wall-shear information, is shown to effectively suppress the linear disturbance in boundary layer flow under the uncertainty of Reynolds number. The controller also suppresses the nonlinear disturbance in the boundary layer flow, which would lead to unstable flow regime without control. The flow is relaminarized in the long run. Other effects of the controller on the flow are also discussed.

• 대한기계학회논문집B
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• 제40권8호
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• pp.535-542
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• 2016

본 연구에서는 차량용 슈퍼차져의 원심압축기 출구 공기 유량을 제어하기 위한 모델 기반 적응 제어기를 설계하였다. 원심압축기 모델은 운전 동특성을 확인할 수 있는 해석적 기반으로 개발하였으며, 개발된 모델은 실험과의 검증을 통해 타당성을 확인하였다. 모델 기반 적응제어는 압축기 모델과 적응 제어기로 구성되었다. 피드백 제어는 시스템 파라미터의 변화에 견실 제어가 가능하지 않지만, 적용된 적응 제어는 시스템 파라미터의 변화에 견실 제어가 가능하다. 결론적으로, 모델 기반 제어는 제어 요구 유량에 제어가 이루어지며, 또한 시스템 파라미터가 변화해도 피드백 제어에 비해 견실한 제어가 이루어지는 것을 확인할 수 있다.

• 대한기계학회논문집
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• 제18권3호
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• pp.738-750
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• 1994

The load-sensing hydraulic system which was developed to improve energy efficiency of conventional hydraulic systems has its own properties. The instability of system responses, linearity of a servo valve, robustness for variation of external load, and dynamic interference between hydraulic motors are such properties which have much to do with control properties of the system. The load-sensing hydraulic system has instability tendancy because the load-sensing mechanism makes a positive feedback loop between the motor part and the pump part. A flow property of the servo valve can be said to be linear because the flow through the valve has nothing to do with a load pressure and the flow is strictly proportional to a valve opening which is adjusted by a valve command signal. The resultant control property can be said to be robust because the steady-state control performance is independent to the load actuated on the motor shaft. In the case when one pump simultaneously drives more than two hydraulic motors, the pump outlet pressure is determined by a hydraulic motor of the largest load pressure among all of the hydraulic motors, and, thus, the other motors are dominated by the largest load pressure. That is, the other motors can be said to be interfered by the motor of the largest load pressure.