• Proceedings of the Korean Information Science Society Conference
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• 2003.04a
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• pp.878-880
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• 2003

대부분의 진단 알고리즘은 PMC 모델을 바탕으로 결함의 개수가 t개를 초과하지 않는다는 t-진단가능 시스템의 특성을 이용한다. 하지만, 병렬처리 시스템의 규모가 커짐에 따라 시스템 내에서 발생되는 결함의 빈도가 높아지게 된다. 즉, 진단 알고리즘에서 가정하는 결함의 개수 t는 병렬처리 시스템 안에 있는 노드의 수에 비해 상당히 작은 개수이며, 결함의 개수가 t를 초과할 경우는 거의 고려하지 않았다. 본 논문에서는 결함의 개수가 t개를 초과하는 경우에 대하여 진단의 정확여부를 판단할 수 없는 충분히 작은 개수의 노드가 존재한다는 것을 허락함으로서, 진단 가능한 결함의 최대 수를 증가시키는 알고리즘을 제안한다.

• Journal of the Korean Institute of Intelligent Systems
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• v.5 no.4
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• pp.56-66
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• 1995

본 논문에서는 산업용으로서 널리 이용되고 있는 3상 유도전동기의 전기적 결함에 의해 발생하는 전자진동문제을 체계적으로 검토하고, 이들 진동신호의 주파수스펙트럼을 사용한 전동기의 결함진단 시스템을 신경회로망을 이용하여 구축하였다. 그리고 그 중에서 비교적 자주 발생하는 공극(air-gap)의 정적 편심에 대해 실험을 수행하고, 그 결과를 신경회로망을 이용한 진단법에 적용하여 본 진단법의 유용성을 확인하였다. 또한 현장에서 발생된 전기적인 결함에 대한 진동측정 data를 이용하여 진단이 정상적으로 수행되는가를 조사하여 각 결함을 정확하게 판별할 수 있음을 입증하였다.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10a
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• pp.51-53
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• 1998

컴퓨터 시스템이 복잡해짐에 따라 결함이 발생할 경우 관리자가 직접 결함을 진단하고 처리하기가 쉽지 않다. 본 논문에서는 이러한 문제점에 대한 해결책으로 결함 진단 기법을 사용한 시스템 관리 기능을 개발하였다. 개발된 시스템 관리 기능은 소프트웨어 기법을 사용하여 시스템 동작 중 발생한 결함의 증상을 분석, 진단함으로써 결함에 대한 해결방안을 자동적으로 관리자에게 제시할 수 있는 능력을 구비하고 있다. 클라이언트-서버 구조로 구현되 시스템 관리 기능은 소프트웨어 기법을 활용하기 때문에 추가적인 비용이 소요되지 않고도 기존 컴퓨터 시스템의 결함 관리 서비스에 활용될 수 있다.

• KIPS Transactions on Software and Data Engineering
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• v.12 no.10
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• pp.445-454
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• 2023

Recently, various fault diagnosis studies are being conducted utilizing data from collaborative robots. Existing studies performing fault diagnosis on collaborative robots use static data collected based on the assumed operation of predefined devices. Therefore, the fault diagnosis model has a limitation of increasing dependency on the learned data patterns. Additionally, there is a limitation in that a diagnosis reflecting the characteristics of collaborative robots operating with multiple joints could not be conducted due to experiments using a single motor. This paper proposes an LSTM diagnostic model that can overcome these two limitations. The proposed method selects representative normal patterns using the correlation analysis of vibration and current data in single-axis and multi-axis work environments, and generates residual patterns through differences from the normal representative patterns. An LSTM model that can perform gear wear diagnosis for each axis is created using the generated residual patterns as inputs. This fault diagnosis model can not only reduce the dependence on the model's learning data patterns through representative patterns for each operation, but also diagnose faults occurring during multi-axis operation. Finally, reflecting both internal and external data characteristics, the fault diagnosis performance was improved, showing a high diagnostic performance of 98.57%.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.1
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• pp.11-22
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• 2023

A radiating elements fault diagnosis method with simplified radiation pattern measurement procedure was presented for planar active phased array antenna system. For presenting the mentioned method, the technique for linear approximation based on the radiation characteristics of a planar array configuration and a technique for solving a unique solution problem that occur in process of diagnosing a fault in a radiating elements were presented. Based on the presented method and a genetic algorithm, experimental simulations were performed for radiating element defect diagnosis according to various planar active phased array antenna configurations. As a result, it was confirmed that the presented radiating element fault diagnosis method can be smoothly applied to planar active phased antennas having various configurations.

• Convergence Security Journal
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• v.9 no.2
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• pp.1-6
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• 2009

Most diagnosis algorithms have been done using the characteristic of t-diagnosable system based on PMC model. But as parallel systems grow fast, more faulty units occur in the system. Previous researches are done on the assumption of small number of faulty units in the system. There have been little studies on the system where number of faulty units exceed t. In this study, we assume the number of faulty units exceed t and there exist small number of nodes where the correctness of diagnosis can't be decided, then we propose an algorithm which increase the maximum number of faulty units in diagnosis system.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.2
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• pp.205-210
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• 2014

Recently, pattern recognition methods have been widely used by researchers for fault diagnoses of mechanical systems. A pattern recognition method determines the soundness of a mechanical system by detecting variations in the system's vibration characteristics. Hidden Markov models (HMMs) and artificial neural networks (ANNs) have recently been used as pattern recognition methods in various fields. In this study, a HMM-ANN hybrid method for the fault diagnosis of a mechanical system is introduced, and a rotating wind turbine blade with a crack is selected for fault diagnosis. The existence, location, and depth of said crack are identified in this research. For improving the diagnostic accuracy of the method in spite of the presence of noise, a moment with a few specific frequencies is applied to the structure.

• Annual Conference of KIPS
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• 2014.04a
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• pp.749-752
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• 2014

본 논문에서는 저속으로 동작하는 구름 베어링의 다중 결함 조기 검출을 위해 결함 특징 추출, 효과적인 특징 선택, 선택된 특징을 이용한 결함 분류의 세 단계로 구성된 결함 진단 기법을 제안한다. 1단계에서 이산 웨이블릿 변환을 이용하여 미세성분으로부터 통계적 결함 특징을 추출하고, DET(distance evaluation technique)를 이용하여 추출한 결함 특징 가운데 베어링 다중 결함 검출에 효과적인 특징을 선택한다. 마지막으로 선택된 특징을 k-NN(k-Nearest Neighbors) 분류기 입력으로 사용함으로써 결함을 진단한다. 본 논문에서는 제안한 결함 진단 기법의 성능을 분류 정확도 측면에서 평가한 결과 95.14%의 높은 분류 정확도를 보였다.

• Plant Journal
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• v.11 no.2
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• pp.39-44
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• 2015

According to a research that is based on a previous study, But in a different way, This study shows fault diagnosis of Induction motor bearing which runs in coal-fired power plant industries on Desulfurization absorber agitator using Spectrum analysis of Stator Current and visual inspection. As a result of harmonic content analysis of stator current spectrum, It was possible to detect ball and outer race fault frequency. The comparison in the context of this experiment proves that the amplitude of faulty frequency is increased in three times at a fault in ball and in outer race. Spectrum analysis of stator current can be used to detect the presence of a fault condition as well as experiment in faulty bearings, besides early fault detection in bearings can prevent unexpected power generation loss and emergency maintenance cost.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.10
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• pp.717-727
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• 2022

An algorithm is realized for estimating the component fault and health diagnosis such as a deterioration. Based on the turbofan engine health diagnosis model, from the health parameters which are estimated by a real time tracking filter, the outliers are eliminated efficiently by an effective median filter to minimize an false alarm. The difference between the fault and deterioration trends is identified by the detection measure for abrupt change, thereby the clear diagnosis classifying the fault and the health condition is possible. The effectiveness of the algorithm for fault and health diagnosis is verified from the simulated results of engine component faults and deterioration.