• 한국해양공학회지
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• 제14권3호
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• pp.20-28
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• 2000

Using the hydraulic and numerical model of semi-enclosed bay (Chinhae Bay), the efficiencies of flow-control structures on the seawater-circulation in the inner bay were investigated. Expecially, this study was confirmed the effectiveness of the flow-control structures at the mouth and narrow channel of Chinhae Bay through the experiments. The system of flow-control structures could enhance the water exchange improvement appropriately. The results of this study can be used as the long-term and integrated environmental impact assessment model in the inner bay.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2004년도 추계 학술대회논문집
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• pp.25-28
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• 2004

The purpose of this paper is to present essential numerical data of FCV(Flow rate Control Valve) which is used in a projectile ejection system for a underwater vehicle. A commercial CFD code is applied to analyze the 3 dimensional viscous compressible flow field within the FCV as four cases of opening rate, 25, 50, 75, and $100\%$. The flow coefficient of each cases are mainly calculated. And other characteristics such as the location of shock wave and total temperature distribution are also determined.

• International Journal of Aerospace System Engineering
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• 제2권1호
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• pp.6-11
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• 2015

An active flow control technique using blowing and distributed suction on low Reynolds airfoil is investigated. Simultaneous blowing and distributed suction can recirculate the jet flow mass, and reduce the penalty to propulsion system due to avoiding dumping the jet mass flow. Energy is injected into main flow by blowing on the suction surface, and the low energy boundary flow mass is removed by distributed suction, thus the flow separation can be successfully suppressed. Aerodynamic lift to drag ratio is improved significantly using the flow control technique, and the energy consumption is quite low.

• 한국반도체및디스플레이장비학회:학술대회논문집
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• 한국반도체및디스플레이장비학회 2002년도 추계학술대회 발표 논문집
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• pp.115-116
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• 2002

This study aimed to investigate flow measurement by using a 'bucket and stop-watch' method of flow measurement. Most flow measurement systems measure pressure or other fluid properties to infer flow rate, though time is a variable which can be easily and very accurately measured. The main principle behind the method was to fill up a reservoir until a set pressure had been reached. This reservoir would then be emptied and the cycle would repeat itself. The prototype was designed to control flow rate using the method. It made use of computer control with an analogue digital converter and fast acting solenoid valves which controlled the flow into a reservoir. Reservoirs were available with internal diameter of 1mm up to 5.5mm to cope with a range of flow rate.

• 한국가시화정보학회지
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• 제22권2호
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• pp.44-54
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• 2024

This study investigates the effectiveness of using a plasma actuator for active control of turbulent flow around a finite square cylinder. The primary objective is to analyze the impact of plasma actuators on flow separation and wake region characteristics, which are critical for reducing drag and suppressing vortex-induced vibrations. Direct Numerical Simulation (DNS) was employed to explore the flow dynamics at various operational parameters, including different actuation frequencies and voltages. The proposed methodology employs a neural network trained using the Proximal Policy Optimization (PPO) algorithm to determine optimal control policies for plasma actuators. This network is integrated with a computational fluid dynamics (CFD) solver for real-time control. Results indicate that this deep reinforcement learning (DRL)-based strategy outperforms existing methods in controlling flow, demonstrating robustness and adaptability across various flow conditions, which highlights its potential for practical applications.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 1991년도 춘계공동학술대회 발표논문 및 초록집; 전북대학교, 전주; 26-27 Apr. 1991
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• pp.77-89
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• 1991

One of the important problems concerning the efficient operation of an automated manufacturing system is the flow control problem. Most research papers about scheduling and control of a FMS consider fabrication, machining and assembly independently. In this paper an effective flow control strategy for a FMS with an assembly subsystem which may be called FMAS (Flexible Machining and Assembly System) is designed using the operation-oriented and, combined Push and Pull control method. The flow control system to be described here could meet production demands with a minimum makespan while satisfying assigned due-dates and keeping a low volume of work-in-process at the same time. The control mechanism also considers machine failures and rush jobs.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2003년도 The Fifth Asian Computational Fluid Dynamics Conference
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• pp.35-35
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• 2003

• 수산해양기술연구
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• 제26권2호
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• pp.213-217
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• 1990

본 연구에서는 유량제어 조직밸브의 기초특성을 집중정수계 모델을 사용하여, 해석하고, 이것을 실험적으로 확인하였다. 그 결과를 요약하면 아래와 같다. 1. 로직밸브의 주밸브 유량은, 그것보다 매우 소유량인 파일럿 유량에 의하여 제어할 수 있다. 2. 주밸브(파핏밸브)~파일럿실간의 개구면적이 주밸브 변위에 비례하도록 밸브를 설계함으로써 주밸브변위(혹은 면적)와 부하유량사이에 양호한 직선성이 얻어진다. 3. 유량제어 로직밸브에서 주밸브 유량의 제어범위의 상한은 기름홈의 개구면적의 최대치에 의하여 결정한다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.458-462
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• 2004

The hydraulic system for discharging compressed gas is composed of compressor tank, proportional flow control servo valve, expulsion spool valve and discharging tube. Purpose of this study is to control of expulsion spool valve. First, we analyzed the hydraulic system. The flow control servo valve is modeled as a 2nd order transfer function and friction force of the expulsion spool valve is modeled as nonlinear model with stribeck effect. However, it is difficult to include the flow reaction force in modeling. So, we exchanged from the simplified flow reaction force of the compressed gas affection into the flow analysis code written in FORTRAN code. Our simulation of the oil pressure system for discharging gas used MATLAB/Simulink. So, we realized ＆apos;Level -2 S-Function Fortran＆apos; to cooperate for MATLAB/Simulink and FORTRAN code. PD controller is selected to control in this system. Simulation results show that with given conditions the controllers give a good tracking performance.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.161-164
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• 2002

In the present study, a passive control method, using the porous wall and cavity system, is applied to the shock wave/boundary layer interactions in transonic moist air flow. The two-dimensional, unsteady, compressible Navier-Stokes equations, which are fully coupled with a droplet growth equation, are solved by the third-order MUSCL type TVD finite difference scheme. Baldwind-Lomax turbulence model is employed to close the governing equations. In order to investigate the effectiveness of the present control method, the total pressure losses of the flow and the time-dependent behaviour of shock motions are analyzed in detail. The computed results show that the present passive control method considerably reduces the total pressure losses due to the shock/boundary layer interaction in transonic moist air flow and suppresses the unsteady shock wave motions over the airfoil, as well. It is also found that the location of the porous ventilation significantly influences the control effectiveness.