• 한국기계연구소 소보
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• 통권19호
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• pp.61-68
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• 1989

As the system monitoring technology become required in order to improve the system performance and the productivity, we’ve studied to the detection for the tool wear and the tool breakage using AE sensors that is able to detection of generated high frequency stress pulse at cutting. The detection system is consist of a sensing part, a amplifier part, a signal processing part, and a analysis & output part. The moment (a rms and a kurtosis) of statistical method is used for analysis of AE singnal. The experiment are carried out in a CNC lathe. In this study, we achieved that the amplitude level of the AE signal and statistical moments was largely changed as the tool failure. The change rate of Kurtosis was especially large, but the change rate of the rms was small.

• Corrosion Science and Technology
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• 제10권4호
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• pp.151-155
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• 2011

The iron oxide particles could be resulted from the corrosion of the circulating water system of a power plant. Because it may be one of the trouble materials which affect the power generation efficiency due to the deposition on steam generator tube and turbine blade, the continuous observation of its concentration is very important. The laser induced break-down detection (LIBD) technology was applied to monitor continuously the concentration of corrosion products with the detection limit of ppb level. The measurement system consists of a Nd:YAG pulsed laser, a polarizing beam splitter, a flow-type sample cell, an acoustic emission sensor, a high speed data acquisition board, a personal computer, etc.. The performance test results confirmed that this technology can be effective to monitor the corrosion product concentration of the circulating water system of a power plant.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 C
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• pp.1759-1761
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• 2003

Recently, the development of diagnosis technique with high confidence is important on power equipment, for this reason is use for measurement and analysis of PD with prior appearance of insulation breakdown In this paper, we presents the analysis of trouble signal to use ${\Phi}$-Q method which display 2D and 3D Equipment of simulation has made independently DS for 170kV GIS of one phase with same on field. The detected signal through the sensor of Induction and Acoustic Emission is classified to use characteristic neural network algorithm and then it is analysis.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 추계학술대회 논문집 전기물성,응용부문
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• pp.200-202
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• 2002

The use of ultrasound is proposed as the most economic and practical nondestructive test method for the detectin of electrical degradation in insulating materials. This paper has studied identification and characterization of partial discharge signals according to defects in GIS using AE(acoustic emission)sensor. Analysis of PD signals use $\psi-v-n$, skewness and kurtosis.

• 한국정밀공학회지
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• 제13권11호
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• pp.57-63
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• 1996

Monitoring of grinding troble occurring during the process is classified into the quantitative data which depends upon a sensor and the qualitative knowledge which relies upon an empirical knowledge. Since grinding operation is highly related with a large amount of functional parameters, it is actually deficulty in copying wiht the grinding troubles through the process. To cope with grinding trouble, it is an effective monitoring systems when occurring the grinding process. The use of neural networks is an effective method of detection and/or monitroing on the grinding trouble. In this paper, four parameters which are derived from the AE(Acoustic Emission) signatures are identified, and grinding monitoring system utilized a back propagation learning algorithm of PDP neural networks is presented.

• 한국정밀공학회지
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• 제12권10호
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• pp.50-56
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• 1995

Chatter Vibration is an unwanted phenomenon in metal cutting and it always affects surface finish, tool life, machine life and the productivity of machining process. The real-time detection of the chatter vibration is is necessarily required to automation system. In this study, we constructed the multi-sensing system using Tool Dynamometer, Accelermeter and AE sensor. Especially, Acoustic Emission(AE) generated during turning was investigated the possibility for real-time detection of chatter vibration. Turning experiments were performed using carbide insert tip under realistic cutting conditions and tapered workpiece of SM45C. Consquently, the real-time detection using multi-sensing system can be used for Inprocess monitoring of chatter vibration.

• 한국소음진동공학회논문집
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• 제19권4호
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• pp.386-392
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• 2009

This paper reports on the research which investigates acoustic signals acquired in progressive compressing, hole blanking, shearing and burr compacting process. The work piece is the head pin of the electric connector, whose raw material is the preformed steel bar. An acoustic sensor was set on the bed of hydraulic press. Because the acquired signals include the dynamic characteristics generated for all the processes, it is required to investigate signal characteristics corresponding to unit process. The corresponding dynamic characteristics to the respective process were first studied by analyzing the signals respectively acquired from compressing, blanking and compacting process. The combined signals were then periodically analyzed from the grinding to the grinding in the sound frequency domain and in the ultrasonic wave. The frequency of around 9 kHz in the sound frequency domain was much correlated to the tool wear. The characteristic frequency in the acoustic emission domain between 100 kHz and 500 kHz was not only clearly observed right after tool grinding but its amplitude was also related to the wear. The frequency amplitudes of 160 kHz and 320 kHz were big enough to be classified by the noise. The noise amplitudes are getting bigger, and their energy was much bigger as coming to the next regrinding. The signal analysis was based on the real time data and its frequency spectrum by Fourier Transform. As a result, the acousto-ultrasonic signals were much related to the tool wear progression.

• 비파괴검사학회지
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• 제24권5호
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• pp.476-486
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• 2004

본 논문은 두 편으로 구성된 스마트능동레이어 (smart active layer, SAL) 센서 개발에 관한 두 번째 것이다. 이미 첫 번째 논문에서 언급되었지만, 구조물 건전성 감시 (structural health monitoring, SHM)는 구조물 안전 감시의 비용과 편리성을 개선하기 위한 방법으로서, 산업현장에서 그 응용이 점차 증가하는 새로운 기술이며, 최근 실제 응용을 하기 위한 스마트 센서의 개발 및 연구가 매우 활발하다. 본 논문에서는 첫 번째 논문에 기술된 SAL 센서의 이론 및 개념 연구에 이어서 실제 제작 및 적용연구에 관해 기술한다. 본 연구에서는 탄성파 감지를 위한 스마트 압전 센서 SAL을 개발하였는데, 압전 소자, 전자기파 차폐층 (EMI shielding lave.) 및 보호 층(protection layer)으로 구성되었다. 보호층에 일정 간격으로 분포된 압전 센서가 부착되고, 이들을 전기적으로 연결하는 회로층이 위치하고 있다. 모두 4종류의 SAL 센서가 설계, 제작 및 시험되었으며 이에 대해 상세히 기술하고 있다. 본 연구를 통해 SAL 센서는 SHM의 수행과 탄성파에 의한 손상 위치를 표정하는데 적용 가능할 것으로 예상된다.

• 한국항공우주학회지
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• 제31권8호
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• pp.44-49
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• 2003

EFPI (extrinsic Fabry-Perot interferometer) 센서를 이용해 복합재료의 파손 신호를 취득하기 위해서는 파손 신호에 비해 상대적으로 낮은 주파수의 열적, 기계적 준정적 변형에 의해 발생하는 위상 변화를 보상해 주는 기술이 필요하다. 또한 센서의 민감도를 최적화하기 위해 출력 신호의 위상을 쿼드러쳐 (quadrature) 지점에 유지시켜야 한다. 본 논문에서는 EFPI 센서 시스템의 출력 신호 위상을 일정하게 유지시킬 수 있는 안정화 제어 시스템을 개발하였다. 안정화 제어 시스템은 광대역 파장 레이저 광원, 가변 F-P (Fabry-Perot) 필터 그리고 필터를 제어할 수 있는 전자 회로 시스템으로 구성하였다. 개발된 시스템의 위상 제어 성능을 평가하기 위해 복합재료 시편의 인장 실험을 수행하여 인장 변형에 의해 발생하는 위상 변화를 개발된 시스템을 이용해 쿼드러쳐 지점에 일정하게 유지할 수 있음을 보였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.51-52
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• 2007

This paper compared wired Acoustic Emission (AE) signals with wireless AE signals. According to the material and process condition, each process signal has distinguishable characteristic to show each removal phenomenon. Therefore, wired and wireless AE sensors having different bandwidth are complementary for CMP process monitoring. Especially, the AE sensor was used to investigate abrasive and molecular-scale phenomena during CMP process, which was compatible to acquire high level frequency. In experiment, wireless AE system was used to get signals in rotary system, using bluetooth. But, it is possible to acquire only RMS signals, which can not analyze abrasive and molecular-sale phenomena. Second, wired AE system was installed using mercury slip-ring, which is suitable not only for rotation equipment but also for acquiring original signals. The acquired signals were analyzed by FFT for understanding of abrasive and molecular revel phenomena in CMP process, finally, we verified that two types of AE sensor with different bandwidth were complementary for CMP process monitoring.