• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.3
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• pp.197-203
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• 2009

This paper presents a novel method to diagnose magnetization faults produced during magnetization process using stator coils of a brushless dc motor with concentrated windings. It is demonstrated that the stator coil magnetization faults can cause a drop of energy efficiency of the brushless dc motor through computer simulations using a magnetization fault model and efficiency test using compressors. The proposed method diagnoses the stator coil magnetization faults by using an inverter during the brushless dc motor driving test after the magnetization process is completed. An experimental study on the brushless dc motor for compressor shows that the stator coil magnetization faults can be detected with high sensitivity.

• Proceedings of the KIEE Conference
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• 1998.07c
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• pp.1039-1041
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• 1998

This paper presents a practical fuzzy expert system to diagnose various faults occurred in local power systems. This integrated system can diagnose all faults occurred in a transmission network and substations. In this paper. the fuzzy reasoning of the diagnostic process is discussed in detail. The discrimination of false operations and non-operations of protective devices as well as the fault identification scheme are also analyzed together with the fuzzy inference process.

• Nuclear Engineering and Technology
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• v.54 no.5
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• pp.1635-1643
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• 2022

STPA (System-Theoretic Process Analysis) is a widely used safety analysis technique to identify UCAs (Unsafe Control Actions) resulting in potential losses. It is totally dependent on the experience and ability of analysts to construct an information model called Control Structures, upon which analysts try to identify unsafe controls between system components. This paper proposes a formal approach to support the manual identification of UCAs, effectively and systematically. It allows analysts to mechanically extract Process Model, an important element that makes up the Control Structures, from a formal requirements specification for a software controller. It then concisely constructs the contents of Context Tables, from which analysts can identify all relevant UCAs effectively, using a software fault tree analysis technique. The case study with a preliminary version of a Korean nuclear reactor protections system shows the proposed approach's effectiveness and applicability.

• Journal of the Semiconductor & Display Technology
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• v.22 no.1
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• pp.49-53
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• 2023

In this paper, we propose an antirandom pattern-based test method considering power consumption to compensate for the problem that the fault coverage through random test decreases or the test time increases significantly when the DUT circuit structure is complex or large. In the proposed method, a group unit test pattern generation process and rearrangement process are added to improve the problems of long calculation time and high-power consumption, which are disadvantages of the previous antirandom test.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.16 no.27
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• pp.105-111
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• 1993

Human works shift its roll from physical condition to the system supervisory control task In this paper safety-presentation configuration is discussed instead of well-known fault-warning configuration. Of paticular interest was the personal factor which include the cognitive process. Through a performance between each person information processing(d') and decision process($\beta$) was pointed out to explain the sensitivity of personal cognitive process. Impact of uncertainty effect the supervisor having doubt situations. These facts are released by the use of flat fuzzy number of $\beta$ and its learning rate R.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.1
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• pp.27-33
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• 2013

Nowadays, the utilization of renewable energy sources like wind energy is considered one of the most effective means of generating massive amounts of electricity. This is evident in the rapid increase of wind farms all over the world which comprise a huge number of wind turbines. However, the drawback of utilizing wind turbines is that it requires maintenance, which could be a costly operation. To keep the wind turbines in pristine condition so as to reduce downtime, the implementation of CMS (Condition Monitoring System) and FDS (Fault Detection System) is mandatory. The efficiency and accuracy of these systems are crucial in deciding when to carry out a maintenance process. In this paper, a fault detection system based on intelligent clustering method is proposed. Using SCADA data, the clustering model was trained and evaluated for its accuracy through rigorous simulations. Results show that the proposed approach is able to accurately detect the deteriorating condition of a wind turbine as it nears a downtime period.

• ETRI Journal
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• v.42 no.4
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• pp.468-479
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• 2020

The proposed AI processor architecture has high throughput for accelerating the neural network and reduces the external memory bandwidth required for processing the neural network. For achieving high throughput, the proposed super thread core (STC) includes 128 × 128 nano cores operating at the clock frequency of 1.2 GHz. The function-safe architecture is proposed for a fault-tolerance system such as an electronics system for autonomous cars. The general-purpose processor (GPP) core is integrated with STC for controlling the STC and processing the AI algorithm. It has a self-recovering cache and dynamic lockstep function. The function-safe design has proved the fault performance has ASIL D of ISO26262 standard fault tolerance levels. Therefore, the entire AI processor is fabricated via the 28-nm CMOS process as a prototype chip. Its peak computing performance is 40 TFLOPS at 1.2 GHz with the supply voltage of 1.1 V. The measured energy efficiency is 1.3 TOPS/W. A GPP for control with a function-safe design can have ISO26262 ASIL-D with the single-point fault-tolerance rate of 99.64%.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.84-88
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• 2008

The roller bearings play an important role not only sustain radial or axial load of system, but carry out a rotatory movement as a various operating conditions. They happen that incipient faults which were caused by excessive load, manufacturing or assembling process's errors and many other reasons are created. The bearing faults make noise and vibration by a continuous collision of rotatory components, which can lower the quality and stability of auto-transmission. Therefore, it is important to detect the early fault as soon as possible. This paper presents a detecting method for the improvement in quality by developing the program which can be used to analyze and predict the vibrational characteristics caused by roller bearing faults. We completed development of the inspection system of vibration by appling the most efficient detecting methods and verified the system's reliability through experiments.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.4
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• pp.88-96
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• 2004

The sag is phenomenon that magnitude of load voltage temporarily decreases because of power system fault. If a certain equipment in industrial process have any trouble result from sag, it can cause utility to be charged for enormous economics loss. Therefore it need to analyze the characteristic of sag and then mitigation method for sags in distribution system in oder to increase reliability. This paper suggests a sags mitigation method with concentrating on mitigation-device interface method, especially FCL that is Fault Current Limiter. And this effect has been done using PDCAD/EMTDC computer simulation analysis.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.1B
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• pp.22-30
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• 2007

In this paper, to achieve consistency maintenance as well as stable service execution, we build a Fault-Tolerant Object Group framework that provides both of the group management service and the load scheduling service. The group management service supports the object management such as registration and authentication, and provides two schemes for failure recovery using the service priority and the checkpointing. In the load scheduling servile, we improve the effectiveness of service execution through the reasoning process of object loads based on the ANFIS architecture. The effectiveness in the performance of the developed framework is validated through a virtual home-network simulation based on the FTOG framework.