• Transactions of The Korea Fluid Power Systems Society
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• v.8 no.3
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• pp.1-7
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• 2011

As the technologies of electronic device have advanced these days, most of mechanical systems are designed with electronic control unit to take advantage of control parameter adaption to operating conditions and firmware flexibilities as well. On-board diagnosis, which detects the system malfunction and identifies potential source of error with its own diagnostic criteria, and fail-safe that can switch the mode of operation in view of recognized error characteristics enables easy maintenance and troubleshooting as well as system protection. This paper dealt with the development of diagnosis and fail-safe function for proportional flow control valve. All type of errors related to valve control system components are investigated and assigned to a specific hexadecimal codes. Cumulative error detection algorithm is applied in order for the sensitivity and reliability to be appropriate. Embedded simulator which runs simultaneously with system program provides the virtual error simulation environment for expeditious development of error detection algorithm. The diagnosis function was verified both with solenoid valve and embedded simulator test and it will enhance the valve control system monitoring function.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.7
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• pp.682-687
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• 2011

Calibration mirror mechanism has been widely used for on-board calibration with black body. The calibration mirror is deployed to reflect the radiation energy from the black body to the image sensor for calibrating the sensor system. After the calibration, the calibration mirror is stowed not to hide a main optical path. It also has a fail-safe function which can stow the mirror by just removing the input power of motor when the calibration mirror is stopped at certain position during the calibration. In the present work, the operation concept, design, torque analysis and functional test results of the calibration mirror mechanism with the aforementioned function have been introduced and investigated.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.311-312
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• 2012

Blade pitch control system monitors and adjusts angle of the blades and controls rotation speed of blades. This paper shows 2MW pitch system hardware and electric part. Blade pitch system consists of pitch drive, gear box, motor and energy storage. Fieldbus is base on CANopen protocol. Fail-Safe system moves the blades to a safety position in case of any fault condition. The super capacitor energy storage provides emergency back up to the Pitch servo driver during feathering the blades. This paper studied Blade pitch servo driver and a bi-directional DC-DC converter for fail-safe system.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2153-2155
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• 2001

This thesis presents a development of intelligent digital governing system and it's application on Sumjingang Hydro-Power plant. The developed system consists of hardware, software and governing algorithm. The feature of hardware is triplex-modular fail safe redundant system for a safe turbine running. The software consists of operating system and application program. The operating system has real-time and multi-tasking features. And also, application algorithm is composed to run francis type hydro-turbine. The developed digital governing system is applied to Sumjingang hydro-power plant, Korea Hydro Nuclear Power Corporation.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.2883-2885
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• 2000

ATS(Automatic Transfer Switch), the secondary power supply system prepared for' temporary power fail on main in KEPCO in industrial field or running a important system. is developed. In this development, we prove that the proposed system is safe with results in a few environment testing focused on a solution against a poor environment by making virtual environment for a solution on problems of system reliability to switch more safely.

• Journal of Drive and Control
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• v.9 no.4
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• pp.8-13
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• 2012

Recently, researches about the eco-friendly vehicles such as hybrid electric vehicle, fuel cell vehicle and electric vehicle have been actively carried out. The regenerative braking system is a key technology to improve the vehicle energy utilization efficiency because it transforms the kinetic energy to the electric energy through the electric motor. This new braking system requires cooperative control between electric controlled brake and regenerative brake. Therefore, it is necessary to establish fault-diagnosis and fail-safe evaluation criteria to secure reliability of the regenerative braking system. In this paper, the failure types and causes in regenerative braking system were analyzed. The transient behavior characteristics were examined based on fault-diagnosis and fail-safe upon failure of regenerative braking system.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.183-186
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• 1997

This paper presents the new MR rotary brake with a permanent magnet, based on the shear operating mode. Due to the permanent magnet, the MR rotary brake can give the nominal resistance to the external disturbance and give the fail safe capacity to the system even when the power supply is accidentally cut off. As we apply the positive or negative current to the electric magnet coil, the resistance torque of the MR rotary brake can be reduced to the value less than the nominal resistance or increased up to the magnetic saturation point.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.11a
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• pp.91-96
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• 1996

The Dynamic Safety System (DSS) is a compute. based reactor protection system that has fail-safe nature and perform dynamic self-testing. In this paper, the implementation of DSS in PLC is presented for PWR. In order to choose adequate PLC implementation model of DSS, the reliability analysis is performed. The KO-RI unit 2 Nuclear power plant is selected as the reference plant, and the verification is carried out using the KO-RI unit 2 simulator FISA-2.

• Nuclear Engineering and Technology
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• v.55 no.5
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• pp.1533-1540
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• 2023

Self-Powered Neutron Detectors(SPNDs) are used to calculate core power distributions, an essential factor in the safe operation of nuclear power plants. Some detectors may fail during normal operation, and signals from failed detectors are isolated from intact signals. The calculated detailed power distribution accuracy depends on the number of available detector signals. Failed detectors decrease the operating margin by enlarging the power distribution measurement error. Therefore, a thorough reconstruction of the failed detector signals is critical. This note suggests a compressive sensing based methodology that rationally reconstructs the readings of failed detectors. The methodology significantly improves reconstruction accuracy by sorting signals and removing high-frequency components from conventional compressive sensing methodology.

• Fire Science and Engineering
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• v.30 no.4
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• pp.20-26
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• 2016

When the fire takes place in Nuclear Powr Plants(NPPs), the reactor should achieve and maintain safe shut-down conditions and minimize the radioactive material released to the environment. The U.S. Nuclear Regulatory Commission (NRC) has issued numerous generic communications related to fire protection over the past 20 years, after it issued its requirements in the Fire Protection Rule set forth in Title 10, Section 50.48 of the Code of Federal Regulations (10 CFR 50.48) and Appendix R to the 10 CFR 50. The and Nuclear Energy Institute (NEI) has developed a Methodology for Risk Informed Fire Safe-Shutdown Analysis, which is related to the Deterministic Method for Multiple Spurious Operations solutions. The aim of this study was to identify, achieve, and maintain Post-Fire Safe-Shutdown of the Main Control Room (MCR) of the CANDU reactor, even though one train of the multiple Safety Structures, Systems, and Components (SCCs) fail by the technical specification and analysis method.