• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.606-610
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• 2001

Voltage harmonics resulting from current harmonics produced by the nonlinear loads have become a serious problem in many systems. Moreover momentary interruptions and voltage sags are responsible for many of the power quality problems found in typical industrial plants. In this paper, proposed power system using series active power filter is not only harmonic compensation but also harmonic isolation between supply and load, and voltage regulation and unbalance compensation. The effectiveness of the proposed system is verified through computer simulations and experiments

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1998.06a
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• pp.203-207
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• 1998

In this paper, it is shown how Fuzzy Pattern Matching can be applied to diagnosis of the most common faults of Rotating Machinery. The whole diagnosis process has been divided in three steps : Fault Detection, Fault Isolation and Fault Identification, whose possible results are described by linguistic patterns. Diagnosis will consist in obtaining a set of matching indexes that indexes that express the compatibility of the fuzzified features extracted from the measured vibration signals, with the knowledge contained in the corresponding patterns.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.739-743
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• 2000

With significant development of power electronics technology the proliferation of nonlinear loads such as such as static power converters has deteriorated power quality in power transmission distribution systems. Notably voltage harmonics resulting from current harmonies produced by the nonlinear loads have become a serious problem in many systems Moreover momentary interruptions and voltage sags are responsible for many of the power quality problems found in typical industrial plants. Int his paper proposed 3 phase hybrid series active power filter is not only for harmonic compensation but also for harmonic isolation between supply and load and for voltage regulation and imbalance compensation Through computer simulations we have verified the effectiveness of the proposed system.

• Journal of the Korean Operations Research and Management Science Society
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• v.16 no.2
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• pp.148-158
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• 1991

The Built-In-Test (BIT) system is an integrated subsystem for the determination of the health status of any primary system. The BIT consists of hardware and software installations directed at performance of the functions of fault detection, diagnosis and isolation, as well as primary system record failure information. Evaluation of the difinitions appropriate to the BIT system, including system characteristics and parameters, is important to an understanding of system functions. The object of this paper is to present general definitions of the BIT diagnosis parameters and a semiquantiative evaluation method for BIT systems. Finally, two case studies for actual problem solutions are included.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.6
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• pp.601-607
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• 2010

For commercial success of emerging service robots, the fault tolerant technology for system reliability and human safety is crucial. Traditionally fault tolerance methods have been implemented in application level. However, from our studies on the common design patterns in fault tolerance, we argue that a framework-based approach provides many benefits in providing reliability for system development. To demonstrate the benefits, we build a framework-based fault tolerant engine for OPRoS (Open Platform for Robotic Services) standards. The fault manager in framework provides a set of fault tolerant measures of detection, isolation, and recovery. The system integrators choose the appropriate fault handling tools by declaring XML configuration descriptors, considering the constraints of components and operating environment. By building a fault tolerant navigation application from the non-faulttolerant components, we demonstrate the usability and benefits of the proposed framework-based approach.

• Journal of the Earthquake Engineering Society of Korea
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• v.2 no.3
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• pp.37-49
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• 1998

Research and a, pp.ication of earthquake protection system in Taiwan have become very active since about ten years ago. Many passive isolators, etc., have been studied extensively. These studies have resulted in a few practical a, pp.ications and proposals of two draft design provisions for seismic isolation design of bridges and buildings. In addition to the pass control, analytical studies on active semi-active control have also been very active and the experimental studies have scheduled in the near future. This paper summarise the progress on recent research and a, pp.ication of earthquake protection systems in Taiwan. The emphases are given to the control systems that have been a, pp.ied in practical a, pp.ications.

• Proceedings of the KIEE Conference
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• 2001.11c
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• pp.42-45
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• 2001

In the speed-sensorless induction motor control systems, only a few percents of error in current measurement badly deteriorates the control performance. And early detection and accomodation of the faults of current sensor is very important to enhance the reliability of the induction motor control system. In this paper, we propose two sensor fault detection schemes having desired functions; fault detection, isolation of failed sensor and compensation of fault effect. The two schemes operate in real-time and employ EKFs (Extended Kalman Filter) for residual generation. Simulation results show that the proposed schemes are very useful in maintaining the control performance of the induction motor driven servo systems even in the face of sensor faults.

• IEMEK Journal of Embedded Systems and Applications
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• v.11 no.6
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• pp.335-341
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• 2016

As information technology advances rapidly, various smart devices are becoming an essential element in our lives. Smart devices are providing services to users through applications up on the operating system. Operating systems have a variety of rules, such as scheduling applications and controlling hardwares. Among those rules, it is significant to protect private information in the information-oriented society. Therefore, isolation task, that makes certain memory space separated for each application, should highly be guaranteed. However, modern operating system offers the function to access the memory space from other applications for the sake of debugging. If this ability is misused, private information can be leaked or modified. Even though the access authority to memory is strictly managed, there exist cases found exploited. In this paper, we analyze the problems of the function provided in the Android environment that is the most popular and opened operating system. Also, we discuss how to avoid such kind of problems and verify with experiments.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.3
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• pp.284-290
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• 2000

The measurement of electric current using optical techniques provides a number of important practical advantages including effective isolation from high line potentials and freedom from the saturation effects observed in conventional current transformers. In this work the optical current sensor which uses thin YIG(Yittrium Ion Garnet) film as a Faraday element has been developed. We have characterized this optical current sensor and implemented it to the OOCR(Opto-electronic OverCurrent Realy) Performance of the OOCR shows the possibility of replacing the present overcurrent relays with OOCR.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.4
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• pp.254-260
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• 2000

This paper deals with the development of fault tolerant control for a nonlinear boiler system with noise and disturbance. The MCMBPC(Multivariable Constrained Model Based Predictive Control) is adopted for the control of the specific boiler turbin model. The fault detection and diagnosis are accomplished with the Kalman filter and two bias estimators. Once a fault is detected, two Bias estimators are driven to estimate the fault and to discriminate Process fault and sensor fault. In this paper, a fault tolerant control scheme combining MCMBPC with a fault compensation method based on the bias estimator is proposed. The proposed scheme has been applied to the nonlinear boiler system and shown a satisfactory performance through some simulations.