• 한국정밀공학회지
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• 제30권7호
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• pp.667-672
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• 2013

This paper presents the development of a condition monitoring system that monitors the operating conditions of a reduction unit, such as the bearing temperature, gearbox vibration, and gear oil deterioration, and notifies the operator of potential problems or abnormal conditions. A series of field tests on high-speed rail and conventional lines was performed to identify the characteristics of temperature rise and vibration levels on the reduction unit during operation. The monitoring system was designed based on the proper sensor selection, measurement method, and signal analysis to optimize the interface with the operating system of high-speed trains. Application of this monitoring system to high-speed trains will play an important role in their proper maintenance and safe operation.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 제2회 학술대회 논문집 일렉트렛트 및 응용기술전문연구회
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• pp.36-39
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• 2000

This paper presents the technology of condition diagnosis & life estimation on insulation system of the traction motor. In the non-destructive methods for diagnosis of coil insulation state, residual dielectric strength is estimated by the D-map which consist of the partial discharge quantity Q and average degradation degree $\Delta$. In the operating history of machine, the N-Y life estimation method is based on the stop-starting numbers and operating times with considering each degradation factor by the thermal, electrical and heat-cycle stress. With the on-line conditioning monitoring on the currents of traction motors, detecting the abnormal operating state due to bearing faults, stator or armature faults, eccentricity related faults and broken rotor bars can be performed.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 제35회 춘계학술대회
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• pp.53-62
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• 2002

Condition monitoring plays a vital role since it sustains reliable operation of industrial plants and machinery in the pursuit of economic whole life operation. In order to achieve this goal, it is needed to monitor various parameters of mechanical system such as vibration, wear, temperature and etc., and finally to diagnosis the root causes of any possible abnormal machine condition. In this work, a machine failure caused by mechanical looseness was experimentally simulated and on-line measurement of the vibration, wear and temperature were simultaneously measured. For the quantitative analyses of machine wear, several statistical parameters of the wear particle size distribution were obtained through the center moment method of the Weibull distribution function, and they were compared to vibrational characteristics. Results showed that the wear and vibrational characteristics did not reveal a strong correlation each other in a loosely supported proceeding bearing.

• 비파괴검사학회지
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• 제14권1호
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• pp.16-22
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• 1994

일반적으로 구름 베어링 시스템에 비해 발전용 터어빈이나 내연기관 엔진과 같은 저어널 베어링을 가진 시스템은 상대적으로 대형 설비이거나 더 가혹한 운전조건에서 가동되는 경우가 많다. 이런 회전기계류에서의 베어링의 파손은 설비의 운전 중단 및 관련 설비의 파손까지도 초래할 수 있게 된다. 따라서 이로 인한 보수에 소비되는 시간 및 경제적인 손실등을 피하기 위해서는 저어널 베어링의 조기파손 감지의,역할은 매우 중요하게 된다. 본 연구에서는 음향방출 기술을 이용하여 베어링에서 발생할 수 있는 파손의 조기검출을 위해 실험실용으로 직접 제작한 저어널 베어링 시스템을 이용하여 여러 형태의 비정상 조건을 만들어 가며 실험을 행하였다. 베어링 손상 및 피로의 주 요인으로서는 윤활유 부족, 윤활층에의 이물질의 혼입, 조립 불량 등이 대표적인 원인으로서 알려져 있으며 이에 근거하여 실험 조건을 윤활유에의 이물질 혼입, 윤활유 부족, 그리고 축과 베어링간의 금속간 접촉등의 인위적인 형태로 구성하여 실험하였다. 그 결과로서 음향방출 기술이 저어널 베어링의 조기파손 감지에 매우 효과적인 도구라는 것을 입증하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 춘계학술대회 논문집
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• pp.642-643
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• 2013

• Journal of Advanced Marine Engineering and Technology
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• 제28권2호
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• pp.285-291
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• 2004

Early detection of an internal malfunction of machinery plays a very important part in all condition monitoring programs. Sensors to detect amplitude. velocity and acceleration are widely used in vibration detection and control. Piezoceramic materials are largely used in sensors and actuators for vibration monitoring and control due to their relatively large output from an induced strain and their arguable self powering characteristics. In this paper a cheap and yet reliable sensors/actuators were developed to detect vibration. The results show that low cost PZT can be designed for optimum detection of bearing vibration. This paper presents the experimental results of a number of piezoceramics characteristics in terms of resonant frequencies and variation of PZT constants with temperature.

• 한국기계가공학회지
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• 제15권4호
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• pp.134-140
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• 2016

Main Spindle System has effect on performance of machine tools and working quality as well as is required of high reliability. Especially, it takes great importance in producing automobiles which includes a large number of working processes. However, main spindle unit in Machine tools are often cases where damage occurs do not meet the design life due to driving in harsh environments. This is when excessive maintenance and repair of machine tools or for damage stability has resulted in huge economic losses. Therefore, this studying propose a method of accelerated life test for diagnosing and prognosis the state of life assessment main spindle system. Time status monitoring of diagnostic data - through the analysis of the frequency band signals were carried out inside the main spindle bearing condition monitoring and fault diagnosis.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 추계학술대회 논문집
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• pp.388-393
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• 2012

Vibration condition monitoring at low rotational speeds is still a challenge. Acoustic emission (AE) is the most used technique when dealing with low speed bearings. At low rotational speeds, the energy induced from surface contact between raceway and rolling elements is very weak and sometimes buried by interference frequencies. This kind of issue is difficult to solve using vibration monitoring. Therefore some researchers utilize artificial damage on inner race or outer race to simplify the case. This paper presents vibration signal analysis of low speed slewing bearings running at a low rotational speed of 15 rpm. The natural damage data from industrial practice is used. The fault frequencies of bearings are difficult to identify using a power spectrum. Therefore the relatively improved method of empirical mode decomposition (EMD), ensemble EMD (EEMD) is employed. The result is can detect the fault frequencies when the FFT fail to do it.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2016년도 추계학술대회
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• pp.819-820
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• 2016

수배전분야는 고압 수배전반, 저압 수배전반, 모터 컨트롤 센터(motor control center; MCC)로 구성되며, MCC는 모터의 운전 및 정지를 할 수 있고, 이상상황 발생 시 비상정지 및 이상 상황에 대한 통보를 할 수 있도록 전자식 모터보호계전기(electronic over current relay; EOCR)가 사용되고 있다. 기존 EOCR은 과전류, 부족전류, 결상, 역상, 전류 불평형, 지락과 같은 전기적 결함 탐지는 가능하지만, 구속보호, 모터 고정자 및 회전자, 베어링 결함과 같은 기계적 결함은 탐지가 어렵다. 본 논문에서는 모터의 전기적, 기계적 결함을 탐지하기 위해 기존 EOCR의 전기적 결함 탐지에 기계적 결함 탐지를 결합하여 회전기기 보호장치를 위한 전기적인 결함과 기계적인 결함을 통합적으로 탐지할 수 있는 시스템을 제안한다. 회전기기 결함탐지를 위한 신호입력부 및 제어부, 시스템 인터페이스, 데이터 획득장치를 설계하였으며, 절연저항 측정, 모터 구속 측정 및 제어, MC 카운터 및 베어링 온도 측정 및 제어를 통해 전기적 결함과 기계적 결함 탐지가 가능하였다.

• Smart Structures and Systems
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• 제20권2호
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• pp.139-150
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• 2017

The structural strain plays a significant role in structural condition assessment of in-service bridges in terms of structural bearing capacity, structural reliability level and entire safety redundancy. Therefore, it has been one of the most important parameters concerned by researchers and engineers engaged in structural health monitoring (SHM) practices. In this paper, an SHM system instrumented on the Jiubao Bridge located in Hangzhou, China is firstly introduced. This system involves nine subsystems and has been continuously operated for five years since 2012. As part of the SHM system, a total of 166 fiber Bragg grating (FBG) strain sensors are installed on the bridge to measure the dynamic strain responses of key structural components. Based on the strain monitoring data acquired in recent two years, the strain-based structural condition assessment of the Jiubao Bridge is carried out. The wavelet multi-resolution algorithm is applied to separate the temperature effect from the raw strain data. The obtained strain data under the normal traffic and wind condition and under the typhoon condition are examined for structural safety evaluation. The structural condition rating of the bridge in accordance with the AASHTO specification for condition evaluation and load and resistance factor rating of highway bridges is performed by use of the processed strain data in combination with finite element analysis. The analysis framework presented in this study can be used as a reference for facilitating the assessment, inspection and maintenance activities of in-service bridges instrumented with long-term SHM system.