• 한국정밀공학회지
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• 제21권12호
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• pp.75-83
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• 2004

With the rotating machinery getting more accurate and diversified, the necessity fur an appropriate diagnosis technique and maintenance system has been greatly recognized. However, until now, the operator has executed a monitoring of the machine by the senses or simple the change of RMS (root mean Square) value. So, the diagnostic expert system using the fuzzy inference which the operator can judge easily and expertly a condition of the machine is developed through this study. In this paper, the hardware and software of the diagnostic expert system was composed and the identification of the diagnostic performance of the developed system for 5 fault phenomena was carried out.

• 한국멀티미디어학회논문지
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• 제25권2호
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• pp.197-205
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• 2022

The Cyber Physical System(CPS) is an important concept in achieving SMSs(Smart Manufacturing Systems). Generally, CPS consists of physical and virtual elements. The former involves manufacturing devices in the field space, whereas the latter includes the technologies such as network, data collection and analysis, security, and monitoring and control technologies in the cyber space. Currently, all these elements are being integrated for achieving SMSs in which we can control and analyze various kinds of producing and diagnostic issues in the cyber space without the need for human intervention. In this study, we focus on implementing a production equipment monitoring system related to building a SMS. First, we describe the development of a fog-based gateway system that links physical manufacturing devices with virtual elements. This system also interacts with the cloud server in a multimedia network environment. Second, we explain the proposed network infrastructure to implement a monitoring system operating on a cloud server. Then, we discuss our monitoring applications, and explain the experience of how to apply the ML(Machine Learning) method for predictive diagnostics.

• 한국지능시스템학회논문지
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• 제24권1호
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• pp.78-83
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• 2014

최근 신재생 에너지원으로서의 선두주자인 풍력발전은 다수의 풍력발전 회사들로 하여금 모니터링 및 고장진단 시스템의 개발을 가속화시키고 있다. 이러한 모니터링 및 진단시스템은 조기의 고장검출을 통해 고장이 발생되었을 경우 발생되는 고가의 수리비용을 미연에 방지할 수 있게 한다. 일반적으로 풍력발전과 관련된 고장진단 시스템은 진동신호 및 신호분석기법에 기반하고 있다. 이에 본 연구에서는 풍력발전 시스템에서 자주 발생되고 있는 질량 불평형 및 축 정렬 불량 등과 같은 기계적인 고장을 효율적으로 진단할 수 있는 시스템을 제안하고자 한다. 본 연구에서 제안된 지능화된 고장진단 알고리즘은 인공신경망기법과 웨이블렛 변환을 이용한 것으로 (주)가온솔루션에서 개발한 풍력발전용 기계적 고장발생 장치에 적용 실험을 통해 제안된 진단기법의 유용성을 확인하고자 하였다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제53권3호
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• pp.168-174
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• 2004

On-line monitoring system(OMS) has been developed for the pumped storage generator/motor The OMS is applied to diagnosis of the PD(partial discharge) activity of stator insulation, the shorted-turn of rotor winding and the variation of the air-gap between stator and rotor. The OMS consists of DAS(data acquisition system), main server system, gateway and display PC. The DAS measures the PD, the shorted-turn and air-gap from three sensors installed on the generator/motor. The gateway controls the data which sent by DAS. The main server system saves the data, analyzes the data and conducts the diagnostic algorithm. The display PC shows the diagnostic results of partial discharge, shorted-turn and air-gap. Field tests were conducted using PDA(partial discharge analyzer). The results of the OMS and PDA measurements can be directly correlated with normalized quantity number(NQN), PD magnitude(Qm) and PD pattern.

• International Journal of Naval Architecture and Ocean Engineering
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• 제10권5호
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• pp.617-628
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• 2018

Several techniques have been developed in the last years for energy conversion and aeronautic propulsion plants monitoring and diagnostics, to ensure non-stop availability and safety, mainly based on machine learning and pattern recognition methods, which need large databases of measures. This paper aims to describe a simulation based monitoring and diagnostic method to overcome the lack of data. An application on a gas turbine powered frigate is shown. A MATLAB-SIMULINK(R) model of the frigate propulsion system has been used to generate a database of different faulty conditions of the plant. A monitoring and diagnostic system, based on Mahalanobis distance and artificial neural networks have been developed. Experimental data measured during the sea trials have been used for model calibration and validation. Test runs of the procedure have been carried out in a number of simulated degradation cases: in all the considered cases, malfunctions have been successfully detected by the developed model.

• 대한기계학회논문집A
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• 제39권1호
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• pp.37-43
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• 2015

압전소자(Piezoelectric transducer, PZT)는 구조물의 안정성 평가를 목적으로 하는 구조 건전성 모니터링 기법(Structural Health Monitoring, SHM)의 센서(sensor) 및 구동기(actuator)로 많이 활용되고 있다. 사용되는 센서 및 구동기의 성능을 사전에 파악하고, 잔존수명 및 결함을 탐지하는 센서 자가 진단법은 안정적인 SHM의 결과를 얻기 위해 매우 중요한 절차이다. 본 연구에서는 Admittance 값을 기반으로 한 센서 자가 진단절차를 통하여 압전체 센서의 결함을 탐지하였으며, 센서 진단과정에 영향을 줄 수 있는 접합층 및 온도 등의 영향인자에 대해 실험적 분석을 실시하였다. 분석 결과 Admittance와 온도 및 접착제의 상관관계를 파악할 수 있었으며, admittance를 기반으로 한 센서 자가 진단 절차를 통해 센서의 접착상태와 접착제의 성능평가가 가능함을 검증하였다.

• 한국정밀공학회지
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• 제13권9호
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• pp.149-155
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• 1996

Recent researches in the trouble monitoring system of grinding process have emphasized the use of deep knowledge. Such works include the monitoring and diagnostic systems for cylindrical grinding using sensors on chatter vibration and grinding burn during the process. But, since grinding operations are especially related with a lalrge amount of ambique parameters, it is effectively difficult to detect the grinding troubles occuring during the grinding process. In this paper, monitoring system for grinding utilizes the neural networks based on grinding power signatures. The monitoring system of grinding operations, which makes use of PDP neural networks, is presented. Then, the implementation results by computer simulations and experimental data with respect to chatter vibration and grinding burn are compared.

• 한국자동차공학회논문집
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• 제11권2호
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• pp.40-47
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• 2003

This paper presents a new evaporative system monitoring method using a virtual HC sensor for an automotive on-board diagnosis. A development was made at providing mathematical expressions from the lambda control information to estimate the HC mass flow purged into the intake manifold from the canister for implementing a virtual HC sensor. The change of the lambda averagevalue reflected the influence of the additional fuel from purging results the sensor estimation of the purged HC amount. Based on this virtual HC sensor, a new evaporative system monitoring method was proposed comparing the amount of purged HC amount with the amount of the HC gas evaporated from the fuel tank and absorbed into the canister. Finally, the method was validated with a simulation using the data logged from the retail car.

• Nuclear Engineering and Technology
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• 제46권6호
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• pp.725-736
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• 2014

It is very important to detect and identify small anomalies and component failures for the safe operation of complex and large-scale artifacts such as nuclear power plants. Each diagnostic technique has its own advantages and limitations. These facts inspire us not only to enhance the capability of diagnostic techniques but also to integrate the results of diagnostic subsystems in order to obtain more accurate diagnostic results. The article describes the outline of four diagnostic techniques developed for the condition monitoring of the fast breeder reactor "Monju". The techniques are (1) estimation technique of important state variables based on a physical model of the component, (2) a state identification technique by non-linear discrimination function applying SVM (Support Vector Machine), (3) a diagnostic technique applying WT (Wavelet Transformation) to detect changes in the characteristics of measurement signals, and (4) a state identification technique effectively using past cases. In addition, a hybrid diagnostic system in which a final diagnostic result is given by integrating the results from subsystems is introduced, where two sets of values called confidence values and trust values are used. A technique to determine the trust value is investigated under the condition that the confidence value is determined by each subsystem.

• 한국산학기술학회논문지
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• 제4권4호
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• pp.352-356
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• 2003

핸드폰 진단시스템의 경우에는 원천기술이 Qualcom차에 의존적이기 때문에 Qualcom사에서 제공되어지는 핸드폰 진단 프로그램을 국내 업체들이 기술이전을 통해서 자사 핸드폰에 적당하게 수정되어 사용하고 있다. 하지만 그 기능이 한정적이기 때문에 사용에 많은 불편함이 있다. 본 논문에서 구현한 핸드폰 진단시스템은 이러한 Qualcom DM 스펙의 미공개와 국내 기술부진 때문에 초래한 문제의 해결점으로 스펙의 개발단계부터 구현까지 하여 단말기의 소프트웨어 개발을 위한 테스트 장비로 사용될 수 있으며 단말기의 고장과 진단을 빠르고 쉽게 할 수 있다. 또한 향후 프로토콜의 보완, 수정, 발전에 능동적으로 대처할 수 있는 연구를 수행하였다.