• 한국컴퓨터정보학회논문지
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• 제28권2호
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• pp.9-17
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• 2023

본 논문에서는 베어링의 결함 진단을 위한 단일 클래스 분류의 진동 이상 탐지 시스템을 제안한다. 베어링 고장으로 인해 발생하는 경제적 및 시간적 손실을 줄이기 위해 정확한 결함 진단시스템은 필수적이며 문제 해결을 위해 딥러닝 기반의 결함 진단 시스템들이 널리 연구되고 있다. 그러나 딥러닝 학습을 위한 실제 데이터 채집 환경에서 비정상 데이터 확보에 어려움이 있으며 이는 데이터 편향을 초래한다. 이에 정상 데이터만 활용하는 단일 클래스 분류 방법을 활용한다. 일반적인 방법으로는 AutoEncoder를 통한 압축과 복원 과정을 학습하여 진동 데이터의 특성을 추출한다. 추출된 특성으로 단일 클래스 분류기를 학습하여 이상 탐지를 실시한다. 하지만 이와 같은 방법은 진동 데이터의 주파수 특성을 고려하지 않아서 진동 데이터의 특성을 효율적 추출할 수 없다. 이러한 문제를 해결하기 위해 진동 데이터의 주파수 특성을 고려한 AutoEncoder 모델을 제안한다. 분류 성능은 accuracy 0.910, precision 1.0, recall 0.820, f1-score 0.901이 나왔다. 주파수 특성을 고려한 네트워크 설계로 기존 방법들보다 우수한 성능을 확인하였다.

• 전기학회논문지P
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• 제57권4호
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• pp.424-430
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• 2008

A new active vibration measurement system in electric power transmission line is presented, using in the nondestructive test. With a permanent magnet and a couple of coils, the system exerts impact force to a test object and in turn picks up the vibration of the object. The natural frequency with the amplitude obtained from the system are used as a basis for the detection of defects in the object. The system is controlled by an electronic device designed to facilitate the fully automated testing process with consistent repeatability and reliability which are essential to the nondestructive test. The system is expected to be applied to the wide area of defect detection including the classification of mechanical parts in production and inspection processes.

• Structural Monitoring and Maintenance
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• 제5권4호
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• pp.507-519
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• 2018

In this paper, damage assessment in wind-turbine towers using vibration-based artificial neural networks (ANNs) is numerically investigated. At first, a vibration-based ANNs algorithm is designed for damage detection in a wind turbine tower. The ANNs architecture consists of an input, an output, and hidden layers. Modal parameters of the wind turbine tower such as mode shapes and frequencies are utilized as the input and the output layer composes of element stiffness indices. Next, the finite element model of a real wind-turbine tower is established as the test structure. The natural frequencies and mode shapes of the test structure are computed under various damage cases of single and multiple damages to generate training patterns. Finally, the ANNs are trained using the generated training patterns and employed to detect damaged elements and severities in the test structure.

• 한국소음진동공학회논문집
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• 제16권4호
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• pp.404-413
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• 2006

Induction motors are the workhorse of our industry because of their versatility and robustness. The diagnosis of mechanical load and power transmission system failures is usually carried out through mechanical signals such as vibration signatures, acoustic emissions, motor speed envelope. The motor faults including mechanical rotor imbalances, broken rotor bar, bearing failure and eccentricities problems are reflected in electric, electromagnetic and mechanical quantities. The recent research has been directed toward electrical monitoring of the motor with emphasis on inspecting the stator current of the motor, The stator current spectrum has been widely used for fault detection in induction motor systems. The motor current signature analysis is the useful technique to assess machine electrical condition. This paper describes the motor condition detected by the current signatures Paralleled with vibration signatures analysis of induction motors with the roller bearing and the journal bearing type for large vertical pumps in power plant as examples to discuss for motor fault detection and diagnosis.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 춘계학술대회 논문집
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• pp.81-82
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• 2014

Recently it is often reported about toxic nanomaterials to organisms. In other words, it is called nanotoxicity, toxic nanomaterials have extremely toxic properties. Zinc oxide is widely used as a promising nanomaterials, but some researchers are warning that nanotype zinc oxide has nanotoxicity. One of typical zinc oxide materials is a zinc oxide nanowire, especially, there is no technique which is detecting a zinc oxide nanowire because of its geometric. In here, we use reduced graphene oxide in order to detect zinc oxide nanowire and use DNA immobilized cantilever sensor, we detect graphene wrapped zinc oxide nanowire. Detection of a zinc oxide nanowire is measured by shifting of cantilever's resonance frequency based on vibration theory. It is proved that cantilever sensor is valid for nanomaterial detection. We showed that detection of a zinc oxide nanowire is successful.

• Composites Research
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• 제13권1호
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• pp.89-97
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• 2000

광섬유센서를 이용한 복합적층판의 피로손상 감지 및 진동측정, 그리고 스틸 보에 대한 충격위치 검출에 관한 연구가 수행되었다. 피로과정중의 신호는 복합재료 내에 삽입된 광섬유와 표면에 부착한 광강도형 광섬유센서, 그리고 스트레인게이지로부터 동시에 측정되었다. 진동감지 실험은 복합재료 보의 표면에 광섬유센서를 부착하여 자유진동 및 강제진동 신호를 취득하였다. 충격위치 검출에 관한 실험에서 충격위치는 충격에 의해 발생된 구조물의 진동이 두 센서에 도달하는 시간의 차를 이용하여 구할 수 있다. 광강도형 광섬유센서를 이용하여 반복 피로 신호를 잘 취득할 수 있었으며 스트레인게이지에 비하여 피로저항성이 우수함이 확인되었다. 광섬유센서는 갭센서와 동일하게 진동신호를 감지하였고 구조물에 가해진 충격위치를 비교적 정확히 검출할 수 있었다.

• 대한후두음성언어의학회지
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• 제18권1호
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• pp.26-32
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• 2007

Objective and Background: Laryngeal stroboscope is an useful equipment in evaluation of vocal cord vibration and in early detection of mucosal lesion including invasive cancer of the vocal cord. Recently Lee et al. (2006) developed portable stroboscope using voice as synchronization signal. It has been frequently impaired ability to synchronize the flashes even in normal female. Authors tried to investigate various methods including vibration pick-up, microphone, laryngeal microphone, and contact microphone for development of simple and accurate method like electroglottograph signal. The purpose of this study was to estimate wheher the vibration pick-up is available and is consistent with the signal of EGG. Subjects and Methods: Authors compared the signals between EGG and noncontact method such as voice, contact methods including vibration pick-up, laryngeal microphone, and contact microphone in normal twenty adults (male 10 and female 10). The number of peak in one cycle was compared with the number of the peak in EGG, and the percent of phase difference in the peak was compared with EGG Also, authors tried to investigate which site of vibration pick-up was most effective for synchronization of stobo flashes. Three site including anterior neck below the cricoid cartilage, thyroid ala, and suprahyoid region were analysed. Results: Among various methods for synchronization of strobo flashes, vibration pick-up was most effective method in peak detection. And anterior neck below cricoid cartilage was the most available site of the vibration pick-up. Conclusion: Authors suggest that vibration pick-up is most available and effective method for synchronization of strobo flashes.

• Smart Structures and Systems
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• 제3권3호
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• pp.263-280
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• 2007

In this paper, an improved GA-based damage detection algorithm using a set of combined modal features is proposed. Firstly, a new GA-based damage detection algorithm is formulated for beam-type structures. A schematic of the GA-based damage detection algorithm is designed and objective functions using several modal features are selected for the algorithm. Secondly, experimental modal tests are performed on free-free beams. Modal features such as natural frequency, mode shape, and modal strain energy are experimentally measured before and after damage in the test beams. Finally, damage detection exercises are performed on the test beam to evaluate the feasibility of the proposed method. Experimental results show that the damage detection is the most accurate when frequency changes combined with modal strain-energy changes are used as the modal features for the proposed method.

• 한국HCI학회:학술대회논문집
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• 한국HCI학회 2009년도 학술대회
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• pp.158-162
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• 2009

적절한 촉각자극은 사운드 효과의 실감성을 증진시킬 수 있다. 예를 들어, 게임이나 영화 등에서 총소리와 함께 발생하는 진동자극은 감상자의 몰입감을 향상시킬 수 있다. 이러한 맥락에서 음향만을 담고 있는 기존 사운드 파일에 촉각자극정보를 부가하여 사운드 플레이와 함께 햅틱장치를 통해 진동자극을 준다면 좀 더 사실감 있는 사운드 체험을 할 수 있을 것이다. 본 논문에서는 사운드 파일을 분석하여 그에 따른 촉각자극정보를 생성하는 방법을 제안한다. 촉각자극정보란 사운드 파일 내에서 특정 소리가 발생하는 시간위치와 발생시켜야 하는 촉각자극패턴이다. 수작업으로 이러한 촉각자극정보를 생성하는 것은 많은 수고를 필요로 한다. 본 논문은 이러한 수작업을 대체할 수 있도록, 사운드 파일에서 특정 소리의 발생시점을 검색할 수 있는 사운드 감지 알고리즘과 촉각자극정보 생성방식을 제안한다. 사운드 감지 알고리즘은 검색하고자 하는 사운드의 주파수 특성을 이용하여 유사한 특성을 가지는 시점들을 찾아낸다. 개발한 알고리즘을 실험한 결과, 5가지 서로 다른 사운드에 대해 98% 이상의 감지 성공률을 얻을 수 있었다. 연구 결과를 종합하여 GUI기반의 진동패턴 생성 유틸리티를 개발하였다. 이 유틸리티를 이용하면 사운드 파일에서 특정 소리의 발생 부분을 자동으로 검색하고, 그 시점마다 원하는 진동정보를 손쉽게 생성할 수 있다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.1401-1409
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• 2007

This paper presents a detecting technique for the improvement in quality by appling the various vibrational characteristics theory. The object of this study is to objectively point out faulty gear by developing the program which can be used to analyze and predict the vibrational characteristics caused by gear wear, deformation and nick of auto-transmission. The fault detection methods by vibrational signal analysis of gear have been progressed in the various fields of industry. These methods have the advantage of being easy to attach the accelerometer without discontinuance of the structure. But not all the methods are efficient for finding early faults. So in the thesis, we completed development of the inspection system of vibration by appling the most efficient detecting methods and verified the system's reliability through experiments.