• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.8A
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• pp.1407-1416
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• 2001

인터넷 서비스를 구내망에 제공하기 위한 인트라넷에서도 인터넷과 동일하게 고속 멀티미디어 및 QoS 보장형 서비스의 요구가 증가하고 있다. 이러한 요구를 충족시키기 위해서 인트라넷에서도 서비스별 트래픽 관리와 망자원의 효율적인 관리가 필요하게 되었다. 본 논문에서는 TINA 체계의 장애관리 기능에 따른 관리를 위해 인트라넷을 각각의 Layer Network 관점에서 재구성하였다. 효율적인 장애관리를 위한 기능 구조를 제안하고, 제안된 구조와 TINA 표준에 따라 장애관리 연사객체를 설계 및 구현한다. 또한, 경보 상관 관계 분석 및 장애 위치 식별 및 국지화(localization)를 위해 인트라넷에서의 장애원인 및 결과 관계를 나타내는 Fault Causality Graph를 제안한다.

• Journal of Ocean Engineering and Technology
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• v.16 no.5
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• pp.61-65
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• 2002

The fault detection and diagnosis of rotating machinery widely used in plants including the ship are important for maintaining the performance of Plants. Recently, the wavelet transform has been recognized an efficient method to detect a little variation of physical quantities by the synchronous localization of time and frequency domains using the translation and dilation of signals. In this Paper, In order to develop efficient and reliable fault detection and diagnosis system rotating machines, the performance of wavelet transformation to detect a little variation of machine status and neural network to diagnose the cause of machine faults are investigated and experimented.

• Proceedings of the KSR Conference
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• 2002.10a
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• pp.503-508
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• 2002

According to passengers gain and headway's contraction, railway vehicle is required quick and correct running. The importance of ATC device was increased gradually, and also is acting important role in safe train running and efficient use in this reason. Now, railway vehicle that is manufactured or is remodeled are designed to most automatic driving system, and ATC device design direction than other device of railway vehicle influences to whole system in this reason. Also, according as system becomes complicated gradually, importance of fault tracing function fur ATC device is emphasized gradually, and in this reason research about efficient fault tracing method is to act important role heightening reliability of ATC device. In this document, that analyzing about result through examination of automatic train operation system of localization model ATC device(SG-100) and application example, and do so that investigate about efficient fault Bracing.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.12
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• pp.1683-1689
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• 2014

In this paper, we propose an image processing based time-frequency domain reflectometry(TFDR) in order to estimate the fault location of a cable. The Wigner-Ville distribution is used for analysis in both the time domain and the frequency domain when the conventional TFDR estimates the fault location in a cable. However, the Winger-Ville distribution is a bi-linear function, and hence the cross-term is occurred. The conventional TFDR cannot estimate the accurate fault location due to the cross-term in case the fault location is close to the position where the reference signal is applied to the cable. The proposed method can reduce the cross-term effectively using binarization and morphological image processing, and can estimate the fault location more accurately using the template matching based cross correlation compared to the conventional TFDR. To prove the performance of the proposed method, the actual experiments are carried out in some cases.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.04a
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• pp.681-688
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• 2009

This paper deals with a bearing faults localization technique based on holographic approach by visualizing sound radiated from the faults. The main idea stems from the phenomenon that bearing faults in a moving vehicle generate impulsive sound. To visualize fault signal from the moving vehicle, we can use the moving frame acoustic holography [H.-S. Kwon and Y.-H. Kim, "Moving frame technique for planar acoustic holography," J. Acoust. Soc. Am. 103(4), 1734-1741, 1998]. However, it is not easy to localize faults only by applying the method. This is because the microphone array measures noise (for example, noise from other parts of the vehicle and the wind noise) as well as the fault signal while the vehicle passes by the array. To reduce the effect of noise, we propose two ideas which utilize the characteristics of fault signal. The first one is to average holograms for several frequencies to reduce the random noise. The second one is to apply the partial field decomposition algorithm [K.-U. Nam, Y.-H. Kim, "A partial field decomposition algorithm and its examples for near-field acoustic holography," J. of Acoust. Soc. Am. 116(1), 172-185, 2004] to the moving source, which can separate the fault signal and noise. Basic theory of those methods is introduced and how they can be applied to localize bearing faults is demonstrated. Experimental results via a miniature vehicle showed how well the proposed method finds out the location of source in practice.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.10
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• pp.67-78
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• 2003

As optical network technology advances and high bandwidth Internet is demanded for the exponential growth of internet traffic volumes, the Dense-Wavelength Division Multiplexing (DWDM) networks have been widely accepted as a promising approach to the Next Generation Optical Internet (NGOI) backbone networks for nation wide or global coverage. Important issues in the NGOI based on DWDM networks are the Routing and Wavelength Assignment(RWA) problem and survivability. Especially, fault/attack detection, localization and recovery schemes in All Optical Transport Network(AOTN) is one of the most important issues because a short service disruption in DWDM networks carrying extremely high data rates causes loss of vast traffic volumes. In this paper, we suggest a fault/attack management model for NGOI through analyzing fault/attack vulnerability of various optical backbone network devices and propose fault/attack recovery procedure considering Extended-LMP(Link Management Protocol) and RSVP-TE+(Resource Reservation Protocol-Traffic Engineering) as control protocols in IP/GMPLS over DWDM.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.04a
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• pp.1235-1238
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• 2012

오늘날 소프트웨어가 가지는 규모와 복잡성은 날로 심화되고 있으며, 소프트웨어 개발 시 결함을 찾아 내기 위한 테스트에 많은 시간이 소모되고 있는 실정이다. 이러한 문제점을 해결하기 위해 중요한 기술 중 하나가 결함 위치 추적(Fault Localization)이다. 이 기법을 이용하여 결함을 추적하기 위해서는 다량의 테스트 케이스를 필요로 하며, 추가로 테스트 케이스를 작성하는 것은 또 다른 개발 부하이다. 본 논문에서는 이를 해결하기 위해서 분기별 입력 조합 기반 테스트 케이스 생성방법과 시드 결과 기반 테스트 케이스 생성방법을 제안하였다. 개발자는 본 생성방법을 통해 테스트 케이스 생성에 대한 비용 절감을 기대 할 수 있다. 제안하는 내용의 효용성을 검증하기 위해 실제 예제 코드에 적용하여 평가하였다. 두 가지 방법 모두 무작위 생성한 테스트 케이스에 비해 개발자가 직접 생성하는 것과 유사한 테스트 케이스를 생성하고, 제안 방법으로 생성한 테스트 케이스의 신뢰성을 확인하였다.

• Journal of Power Electronics
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• v.14 no.5
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• pp.967-979
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• 2014

This paper focuses on speed and current sensor fault detection and isolation (FDI) for induction motor (IM) drives. A new, accurate and high-efficiency FDI approach is proposed so that a system can continue operating with good performance even in the presence of speed sensor faults, current sensor faults or both. The proposed three paralleled adaptive observers are capable of current sensor fault detection and localization. By using observers, the rotor flux and rotor speed can be estimated which allows the system to run under the speed sensorless vector control mode when a speed sensor fault occurs. In order to detect speed sensor faults, a threshold-based scheme is proposed. To verify the feasibility and effectiveness of the proposed FDI strategy, experiments are carried out under different conditions based on a dSPACE DS1104 induction motor drive platform.

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.1093-1101
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• 2015

Partial Discharge (PD) is a physical phenomenon, which causes defects and damages to the insulation. This phenomenon is regarded as the most important source of fault and defect in power transformers. Therefore, methods of high speed and precision are considered of special importance for the maintenance of transformers in localization of the origin of partial discharge. In this paper, the transformer winding is first modeled in a transient state by using RLC ladder network and multiconductor transmission line (MTL) models. The parameters of the two models were calculated by Ansoft Maxwell software, and the simulations were performed by Matlab software. Then, the PD pulses were applied to the models with different widths of pulses. With regard to the fact that the signals received after the application of PD had a variable frequency nature over time, and based on the wavelet transform and signal energy, a new method was presented for the localization of PD. Ultimately; the mentioned method was implemented on a 20 kV winding distribution transformer. Then, the performances of the models used in this paper, including RLC and MTL models, were compared in different frequency bands for the correct distinction of partial discharge location.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.2
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• pp.239-245
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• 2013

In this paper, we propose a time-frequency domain reflectometry (TFDR) based measurement method for localizing concentric neutrals corrosion on live underground power cable. It consists of two inductive couplers which can transmit the reference signal into live underground power cable and measure the reflected signals from the impedance discontinuities of concentric neutrals corrosion. In order to compensate the dispersion of the measured reflected signal via inductive coupler, an equalizer based on Wiener filtering is designed. To improve the localizing performance of concentric neutrals corrosion in the vicinity of the measurement point, the reference signal is removed from the measured reflected signals. The localization performance of the proposed method is verified by the concentric neutrals corrosion localization experiment.