• 공학교육연구
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• 제20권4호
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• pp.61-66
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• 2017

Automatic flow control system composed by hardware and software was designed and fabricated to be used as teaching tool of feedback control theory in university experimental class. This system includes hardwares like data acquisition board, flow measuring device, transmitters, and the pneumatic valve, and software like LabView program for the monitoring and control of flow rates. The system was designed as the student can see the control effect of not only set point but also disturbance changes. Also the LabView program was composed for the calculation of controller parameters of both Ziegler-Nichols and Cohen-Coon tuning. The students can apply both tuning constants and compare the control performances. This system will provide the easy way for the students to understand the function and specification of control hardwares, and to raise the programing ability of control software.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.1055-1060
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• 2009

Noise is one of the major environmental problems in human life. But hot water distributers with the flow rate control valve bring about often noise according to the heating control condition in residential buildings. The sound power level increased as the flow rate and pressure difference increased. And thus, experimental analyses for the flow rate control and the pressure difference control were carried out in this study to reduce the noise emitted from the flow rate control valve. As the results, the flow rate control method using a SMA(Shape Memory Alloy)-valve and the flow rate control system using a pressure difference sensor can be expected to control noise in the region of below 50 dB of sound power level.

• 한국전산유체공학회지
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• 제6권1호
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• pp.40-46
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• 2001

Pressure-flow control characteristics of a commercially available cerebrospinal flow(CSF) control shunt valve was studied using flow/structure interaction analyses. Pre-stress of the valve diaphragm(membrane) was accounted for the simulation of an actual valve. The present results were in good agreement with the valve specification listed in the commercially available CSF control valve. The flow/structure interaction analysis of the present study can be effectively used to design a variety of CSF control shunt valves.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권1호
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• pp.396-413
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• 2017

Dynamically checking the integrity of software at run-time is always a hot and difficult spot for trusted computing. Control-flow integrity is a basic and important safety property of software integrity. Many classic and emerging security attacks who introduce illegal control-flow to applications can cause unpredictable behaviors of computer-based systems. In this paper, we present a software-based approach to checking violation of control flow integrity at run-time. This paper proposes a high-performance and low-overhead software control flow checking solution, control flow checking at virtual edges (CFCVE). CFCVE assigns a unique signature to each basic block and then inserts a virtual vertex into each edge at compile time. This together with insertion of signature updating instructions and checking instructions into corresponding vertexes and virtual vertexes. Control flow faults can be detected by comparing the run-time signature with the saved one at compile time. Our experimental results show that CFCVE incurs only 10.61% performance overhead on average for several C benchmark programs and the average undetected error rate is only 9.29%. Compared with previous techniques, CFCVE has the characteristics of both high fault coverage and low memory and performance overhead.

• 한국기계가공학회지
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• 제8권2호
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• pp.83-89
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• 2009

An air-fuel ratio control is essential in reducing hazardous exhaust emissions from a compressed natural gas(CNG) engine, and can be accomplished by accurate control of gas injection flow. In this study, theoretical research was conducted on injection characteristics of a solenoid gas injector, and injection experiments for calibration and analysis were performed. Various factors for gas injection flow such as injection pressure, gas temperature, and supply voltage are studied. A dynamic flow equation of the natural gas was proposed on the basis of flow dynamics theories and results of the injection experiment. The verification of the dynamic flow equation of the solenoid injector was carried out with a large CNG-engine applied to an urban bus. Air-fuel ratio control experiments were conducted in both steady and transient state. Results of injection experiments for the solenoid injector and the CNG-engine was proved the control method proposed herein to be effective.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.77-82
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• 2009

If we can supply accurate minute flow rate to the households, we can solve many problems that are occurring in consequences of uncontrolled flow rate for the households. Therefore, this paper presents an innovative solution to the source of the problems by illustrating how we can control the flow rate to the household. This paper proves such problems even can be solved in a case when there is a room turned off the heating.

• 한국정보처리학회논문지
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• 제6권3호
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• pp.750-757
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• 1999

The protocol conformance testing is to check whether an implementation of a protocol conforms to its specification. And it is important to improve the interoperability of protocol and the efficiency of cost. In general, protocol is composed of the control flow representing observable behaviors and the data flow representing internally used variables. Until now, research for generation of test suite has been realized only consideration the control flow of protocol or separation control flow from data flow. Case of considering control flow, contents of test was simple and definite. Length of test was short. But it was of little application, and it didn't manage each kind errors in data flow. Therefore, we must generate test case that can manage control and data flow. So, anomaly of variable must be removed for efficient conformance testing. Therefore in this dissertation, we proposed algorithm which can remove anomaly of variable for efficient conformance testing. And it showed that anomaly of variable was got rid of applying this algorithm to real protocol.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2002년도 ICCAS
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• pp.60.4-60
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• 2002

Nonlinear adaptive control for the laboratory pressure-flow model. Control valves are installed on both sides. The pressure and the outlet flow rate are measured. The pressure and outlet flow rate are controlled variables and the control valve stem positions on both sides are the manipulated variables. The variation in both inputs will influence both controlled variables. The control performance is good, in spite of varying valve coefficients of inlet and outlet.

• 한국정밀공학회지
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• 제14권8호
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• pp.146-154
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• 1997

Solenoid-folw control type ABS is used with a 'dump and reapply' pressure control arrangement instead of using 2/2 (normal open/close) solenoid valves in convensional systems(sol. -sol. control type), a flow control valve is used which replaces the (no) inlet valve. The flow control valve controls fluid flow providing a nearly constant reapply rate( .theta. ) after the dump plase of ABS operation. In this study, to investigate a characteristics of brake pressure by PWM control, test rig was consisted of ABS hydraulic modulator, digital controller, pneumatic power supply and brake master cylinder. For comparison with experi- mental results, system modelling and computer simulation were performed. As a result, experiment results showed fairly agreement with the simulation. Also, it is shown that the pressure gradient (tan .theta. ) is affected by pressure, frequency, duty ratio and expressed with an exponential funtion.

• 유공압시스템학회논문집
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• 제4권1호
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• pp.1-6
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• 2007

The typical hydraulic system of hoist is composed of a hydraulic supply unit, a directional control valve, two pilot operated check valves, two flow control valves. The capacity coefficients of flow control valves should be adjusted for the hoist to operate at moderate speed and minimize the hydraulic energy loss. However, it is difficult to adjust the four capacity coefficients of flow control valves by trial and error for optimal operation. The steady state model of the hoist hydraulic system is derived and the optimal capacity coefficients of flow control valves are obtained using the complex method that is one kind of constrained direct search method.