• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.373-375
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• 2004

The SRM is more robust and lower cost than other type motors. The inverter for SRM cannot have shoot through fault, since a phase winding of SRM is independent of other phase windings. The SRM has high starting torque and high power density. But it has torque ripples due to nonlinear magnetic characteristics. Therefore, SRM has highly non-linear torque producing characteristics. Because fuzzy logic is a flexible and general-purposed method for implementing non-linear dynamic functions, it is effective for the control of high current SRM. We design the fuzzy controller and demonstrate the fuzzy control system by MATLAB.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.207-211
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• 2004

The performance of an inductive position sensor has approved by previous research papers. In this paper, magnetic circuit model of a ring-type multi-pole insuctive position sensor is described. The magnetic circuit model is required to design in ductive position sensor as well as draw a fault tolerance algorithm. Using the magnetic circuit theory, we derived the relationship between voltage applied and flux density in the normal air-gap. By idealizing the modulation/demodulation processes of signal processing circuit, sensor gain with respect to change of displacement is theoretically calculation using the magnetic circuit model, which validate the theoretical derivation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.10
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• pp.1460-1465
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• 2017

Outage areas can be transferred to adjacent feeders to restore power supply in case of the fault on the distribution system. Feeders in the small island or mountain area may not have backup feeders due to the low density of load. In this weakly meshed open loop system, BESS can be used as a backup feeder to improve reliability of power supply. This paper proposes a new network reconfiguration method for BESS based service restoration. Fuzzy decision making technique is adopted to deal with fuzziness of service restoration planning rules. Case studies using KEPCO real distribution system have been performed to verify feasibility of the proposed method.

• Journal of Computing Science and Engineering
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• v.7 no.4
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• pp.272-284
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• 2013

In this paper, we propose a new framework for anomaly detection in medical wireless sensor networks, which are used for remote monitoring of patient vital signs. The proposed framework performs sequential data analysis on a mini gateway used as a base station to detect abnormal changes and to cope with unreliable measurements in collected data without prior knowledge of anomalous events or normal data patterns. The proposed approach is based on the Mahalanobis distance for spatial analysis, and a kernel density estimator for the identification of abnormal temporal patterns. Our main objective is to distinguish between faulty measurements and clinical emergencies in order to reduce false alarms triggered by faulty measurements or ill-behaved sensors. Our experimental results on both real and synthetic medical datasets show that the proposed approach can achieve good detection accuracy with a low false alarm rate (less than 5.5%).

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.760-761
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• 2001

We have studied quench characteristics for current limiting elements of YBCO films in applied fields of 0 - 130 mT. The films were deposited on sapphire substrates and covered by gold top layer. The current limiting element consists of 2 mm wide YBCO stripes connected in series. The electric field - current density (E-J) measurements showed that the presence of applied magnetic fields induces uniform quench distribution for the stripes, otherwise non-uniform quenches were observed. We suggest that suppressing the critical current by increased fields due to fault current effectively forced the stripes of higher Jc(0) to quench, resulting in equalizing quench times.

• Journal of Applied Reliability
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• v.16 no.4
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• pp.347-355
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• 2016

Purpose: With the advance of miniaturization of electronic products, stacked packages of high density semiconductors are commonly used. Potential failure modes and mechanisms of stacked packages are identified. Methods: Failure modes and mechanisms of thin chip stacked packages are determined through the categorization and failure analysis: delamination, non-wet, crack, ESD, EMI and the process related damages. Results: Those failure modes are not easy to find and require excessive amount time and effort for analysis and subsequent improvement. Conclusion: In this study, a method of estimating the failure rate based on the strength measurement is suggested.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.12
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• pp.179-184
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• 2002

In this study, we developed a portable device which can monitor and analyze vibration signals from machines. This system consists a PDA loading the program for vibration analysis and A/D board for vibration acquisition. A PDA is smaller than the palm of the hand, but it has a powerful computing ability as much as an IBM compatible PC with a Pentium 100MHz CPU. The A/D board developed in this study supports LAN interface using TCP/IP communication protocol. The application program for vibration analysis includes signal processing module, fault diagnosis module, data store module, and plot display module. MS visual embedded C＋＋ 3.0 was used to developed the program.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.97.2-97
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• 2002

A method for the non-destructive detection of damage using parameterized partial differential equations and Galerkin approximation techniques is presented. This method provides the theoretical and experimental verification of a nondestructive time domain approach to examine structural damage in smart structure. The time histories of the vibration response of structure were used to identify the presence of damage. Damage in a structure causes changes in the physical coefficients of mass density, elastic modulus and damping coefficient. This paper examines the beam-like structures with PVDF sensor and PZT actuator to perform identification of those physical parameters and to detect the...

• Journal of Korea Foundry Society
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• v.17 no.2
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• pp.188-194
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• 1997

The effects of solidification condition and vibration on structure refinement were investigated for unidirectionally solidified $Al-CuAl_2$ eutectic composites. Eutectic composites were unidirectionally solidified under vibration with different growth rates (R) and thermal gradient(G). The lamellar structure was varied according to growth condition (G/R ratio). For the structure refinement the effect of G/R was found out to be greater than that of vibration. The interlamellar spacing(${\lambda}$) in this materials was varied with the growth rates(R) with "${\lambda}^2R$=Constant" relationship.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.398-399
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• 2015

The fault level of power transmission lines caused by natural disaster such as lightning and rainstorm has been on the rise. Especially, the cause of lightning stokes is large part of transmission faults. In order to reduce the lightning failures, it is necessary to measure and analyze the lightning characteristics. This paper deals with observation of the lightning strokes by KEPCO Lightning Detection Network(KLDNet) and analysis including lightning density, multiplicity and amplitude distribution.