• The KSFM Journal of Fluid Machinery
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• v.12 no.5
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• pp.7-12
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• 2009

A nuclear fuel test loop(after below, FTL) is installed in the IRI of an irradiation hole in HANARO for testing the neutron irradiation characteristics and thermo hydraulic characteristics of a fuel loaded in a light water power reactor or a heavy water power reactor. There is an in-pile section(IPS) and an out-pile section(OPS) in this test loop. When HANARO is operated normally, the fuel loaded into the IPS has a nuclear reaction heat generated by a neutron irradiation. To remove the generated heat and to maintain the operation conditions of the test fuel, a main cooling water system(MCWS) is installed in the OPS of the FTL. The MCWS is composed of a main cooler, a pressurizer, two circulation pumps, a main heater, an interconnection pipe line and instruments. The interconnection pipeline is a closed loop which is connected to an inlet and an outlet of the IPS respectively. The MCWS is under a cold function test during a start-up period. This paper describes the system flow network analysis results of the flow control of a main cooling water system in the HANARO fuel test loop. It was confirmed through the results that the flow was met the system design requirements.

• Advances in Automotive Engineering
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• v.1 no.1
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• pp.123-141
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• 2018

Hardware-in-the-loop (HiL) simulation is a very powerful tool to design, test and verify automotive control systems. However, well-validated and high degree of freedom vehicle models have to be utilized in these simulations in order to obtain realistic results. In this paper, a vehicle dynamics model developed in the Carsim Real Time program environment and its validation has been performed using experimental results. The developed Carsim real time model has been employed in the Tofas R&D hardware-in-the-loop simulator. Experimental and hardware-in-the-loop simulation results have been compared for the standard FMVSS No. 126 test and the results have been found to be in good agreement with each other. Two electronic stability control (ESC) algorithms, named the Basic ESC and the Integrated ESC, taken from the earlier work of the authors have been tested and evaluated in the hardware-in-the-loop simulator. Different evaluation methods have been formulated and used to compare these ESC algorithms. As a result, the Integrated ESC system has been shown superior performance as compared to the Basic ESC algorithm.

• Journal of Ocean Engineering and Technology
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• v.32 no.2
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• pp.131-137
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• 2018

In this paper, we propose an adaptive backstepping controller to control the exact position and orientation of a remotely operated underwater vehicle with parametric model uncertainty. To further improve the angular velocity control precision of each thruster, a phase locked loop (PLL) controller has been added to the backstepping controller. A comparison of two backstepping controllers with and without the PLL control loop has been performed using simulations and experiments. The test results showed that the tracking performance could be improved by using the PLL control loop in the proposed adaptive backstepping controller.

• Proceedings of the KIEE Conference
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• 1999.11c
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• pp.552-554
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• 1999

In this paper, a robust control system with the disturbance observer is proposed for BLDC servo system. The overall control system consists of the speed controller which is implemented with PI controller and the disturbance observer with free parameters. The proposed control system is designed the command input response and the closed loop characteristics independently by using two-degrees-of-freedom concept, so it can improve the closed loop characteristics with no influence on the command input response. The effective suppression of disturbance with the observer improves the characteristics of the closed loop of the system. And also, by fluting the bandwidth of free parameters, measurement noise is considered. To verify the better performance of the proposed control system than that of the conventional PI controllers, the performance of the controller is analyzed theoretically and some simulation results are presented.

• Proceedings of the KSME Conference
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• 2001.06b
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• pp.741-746
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• 2001

This paper presents an investigation of a vehicle-to-vehicle distance control using a Hardware-in-the-Loop Simulation(HiLS) system. Since vehicle tests are costly and time consuming, how to establish a efficient and low cost development tool is an important issue. The HiLS system consists of a stepper motor, an electronic vacuum booster, a controller unit and two computers which are used to form real time simulation and to save vehicle parameters and signals of actuator through a CAN(Controller Area Network). Adoption of a CAN for communication is a trend in the automotive industry. Since this environment is the same as that of a real vehicle, a distance control logic verified in laboratory can be easily transfered to a test vehicle.

• Journal of the Korean Society for Precision Engineering
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• v.5 no.2
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• pp.23-32
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• 1988

A control system for improving the moving accuracy of robotic manipulators with elastic joints is devloped. The dynamics of manipulator system is splitted into two sub-dynamics; of arm-link and actuator rotor- link, which are coupled statically through joint torque. Two contorl loops are implemented respectively around both sub-dynamic systems. Computed torque algorithm with acceleration feedback is used for the arm-link control loop, and for the actuator rotor-link control loop PID algorithm is adopted. The resulting control system is tested through a series of computer simulation for a PUMA type manipulator, The reaults show good performance of the developed control system for wide range of joint stiffness and moving speed.

• Proceedings of the IEEK Conference
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• 2001.06e
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• pp.233-236
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• 2001

In this paper, a robust controller for UPS inverter is designed using CDM (Coefficient Diagram Method) developed by S. Manabe, by which a low order controller guaranteeing the stability and robustness is easily designed. The proposed controller consists of two control loops, the inner current control loop and the outer voltage control loop. The robustness of the proposed controller is verified through the theoretic evolution and its simulation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.4
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• pp.819-825
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• 2016

In this paper, a phase locked loop structure with parallel dual loop which have a different bandwidth has been proposed. The bandwidths depending on transfer functions are obtained through dual loops. Two different bandwidths of each loop are used to suppress noise on the operating frequency range. The proposed phase locked loop has two different voltage controlled oscillator gains to control two different wide and narrow loop filters. Furthermore, it has the locking status indicator to achieve an accurate locking condition. The phase margin of $58.2^{\circ}$ for wide loop and $49.4^{\circ}$ for narrow loop is designed for stable operation and the phase margin of $45^{\circ}$ is maintained during both loops work together. It has been designed with a 1.8V 0.18um complementary metal oxide semiconductor (CMOS) process. The simulation results show that the proposed phase locked loop works stably and generates a target frequency.

• International Journal of Aeronautical and Space Sciences
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• v.11 no.4
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• pp.303-312
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• 2010

This paper introduces the upper stage attitude control system of KSLV-I, which is the first space launch vehicle in Korea. The KSLV-I upper stage attitude control system consists of two electro-hydraulic actuators and a reaction control system using cold nitrogen gas. A proportional, derivative, and integral controller is designed for the electro-hydraulic thrust vectoring system, and Schmidt trigger ON/OFF controllers are designed for the reaction control system. Each attitude controller is designed to have enough stability margins. The stability and performance of KSLV-I upper stage attitude control system is verified via hardware in the loop tests. Hardware in the loop tests are accomplished for perturbed flight conditions as well as nominal flight condition. The test results show that the attitude control loop of KSLV-I upper stage is very stable and the attitude controllers perform well for all flight conditions. Attitude controllers designed in this paper have been successfully applied to the first flight of KSLV-I on August 25, 2009. The flight test results show that all attitude controllers of the KSLV-I upper stage performed well and satisfied the accuracy specifications even during abnormal flight conditions.

• Journal of Power Electronics
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• v.13 no.3
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• pp.447-457
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• 2013

For grid-connected LCL-filtered inverters, resonance yields instability and low bandwidth. As a result, careful designs are required. This paper presents a systematic current control structure, where pole assignment consisting of one or more feedbacks is the inner loop, and the outer loop is the direct grid current control. Several other issues are discussed, such as the inner-loop feedback choices, pole-assignment algorithms, robustness and harmonic rejection. Generally, this kind of strategy has three different types according to the inner-loop feedback choices. Among them, a novel pole-assignment algorithm has been proposed, where the inner control maintains four freely-assigned poles which are just two pairs of conjugated poles located at the fundamental and resonance frequencies separately. It has been found that with the different types, the steady-state and dynamic performances are quite different. Finally, simulations and experiments have been provided to verify the control and design of the proposed methods.