• 대한기계학회논문집A
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• 제27권4호
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• pp.537-543
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• 2003

Transient vibration generated by developing localized fault in gear can be used as indicators in gear fault detection. This vibration signal suffers from the background noise such as gear meshing frequency and its harmonics and broadband noise. Thus in order to extract the information about the only gear fault from the raw vibration signal measured on the gearbox this signal is processed to reduce the background noise with many kinds of signal-processing tools. However, these signal-processing tools are often very complex and time waste. Thus. in this paper. we propose a novel approach detecting the damage of gearbox and analyzing its pattern using the raw vibration signal. In order to do this, the residual signal. which consists of the sideband components of the gear meshing frequent) and its harmonics frequencies, is extracted from the raw signal by the power spectral density (PSD) to obtain the information about the fault and is used as the input data of the artificial neural network (ANN) for analysis of the pattern of gear fault. This novel approach has been very successfully applied to the damage analysis of a laboratory gearbox.

• 한국기계가공학회지
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• 제15권4호
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• pp.23-29
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• 2016

Rotary machine is major equipment in industry. The rotary machine is applied for a machine tool, ship, vehicle, power plant, and so on. But a spindle fault increase product's expense and decrease quality of a workpiece in machine tool. A turbine in power plant is directly connected to human safety. National crisis could be happened by stopping of rotary machine in nuclear plant. Therefore, it is very important to know rotary machine condition in industry field. This study mentioned fault diagnosis algorithm with statistical parameter and empirical mode decomposition. Vibration locations can be found by analyze kurtosis of data from triaxial axis. Support vector of data determine threshold using hyperplane with fault location. Empirical mode decomposition is used to find fault caused by intrinsic mode. This paper suggested algorithm to find direction and causes from generated fault.

• Earthquakes and Structures
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• 제12권6호
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• pp.653-663
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• 2017

A seismic margin assessment evaluates how much margin exists for the system under beyond design basis earthquake events. Specifically, the seismic margin for the entire system is evaluated by utilizing a systems analysis based on the sub-system and component seismic fragility data. Each seismic fragility curve is obtained by using empirical, experimental, and/or numerical simulation data. The systems analysis is generally performed by employing a fault tree analysis. However, the current practice has clear limitations in that it cannot deal with the uncertainties of basic components and accommodate the newly observed data. Therefore, in this paper, we present a Bayesian-based seismic margin assessment that is conducted using seismic fragility data and fault tree analysis including Bayesian inference. This proposed approach is first applied to the pooltype nuclear research reactor system for the quantitative evaluation of the seismic margin. The results show that the applied approach can allow updating by considering the newly available data/information at any level of the fault tree, and can identify critical scenarios modified due to new information. Also, given the seismic hazard information, this approach is further extended to the real-time risk evaluation. Thus, the proposed approach can finally be expected to solve the fundamental restrictions of the current method.

• 드라이브 ㆍ 컨트롤
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• 제9권4호
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• pp.8-13
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• 2012

Recently, researches about the eco-friendly vehicles such as hybrid electric vehicle, fuel cell vehicle and electric vehicle have been actively carried out. The regenerative braking system is a key technology to improve the vehicle energy utilization efficiency because it transforms the kinetic energy to the electric energy through the electric motor. This new braking system requires cooperative control between electric controlled brake and regenerative brake. Therefore, it is necessary to establish fault-diagnosis and fail-safe evaluation criteria to secure reliability of the regenerative braking system. In this paper, the failure types and causes in regenerative braking system were analyzed. The transient behavior characteristics were examined based on fault-diagnosis and fail-safe upon failure of regenerative braking system.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.710-713
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• 2005

In this paper, a design method to detect faults in plants with uncertainties is proposed. When a plant has faults, the plant will be corrupted by an unknown fault signal. In addition, the plant also includes uncertainties, such as disturbances and plant parameter deviations. In this case, the proposed method estimates the fault signal by using an adaptive observer. Numerical examples are given to demonstrate the validity of the proposed method.

• 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.

• Geomechanics and Engineering
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• 제24권5호
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• pp.471-478
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• 2021

Water damage is one of the five disasters that affect the safety of coal mine production. The erosion of rocks by water is a very important link in the process of water inrush induced by fault activation. Through the observation and experiment of fault filling samples, according to the existing rock classification standards, fault sediments are divided into breccia, dynamic metamorphic schist and mudstone. Similar materials are developed with the characteristics of particle size distribution, cementation strength and water rationality, and then relevant tests and analyses are carried out. The experimental results show that the water-rock interaction mainly reduces the compressive strength, mechanical strength, cohesion and friction Angle of similar materials, and cracks or deformations are easy to occur under uniaxial load, which may be an important process of water inrush induced by fault activation. Mechanical experiment of similar material specimen can not only save time and cost of large scale experiment, but also master the direction and method of the experiment. The research provides a new idea for the failure process of rock structure in fault activation water inrush.

• 지질공학
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• 제27권1호
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• pp.91-101
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• 2017

단층물질은 불균질하고 복잡한 메커니즘에 의해 생성되기 때문에 지역, 암종 및 구성 성분에 따라 다양한 특성을 보인다. 본 연구에서는 단층물질의 물리 역학적 특성을 규명하기 위해 국내에 분포하는 단층물질 109개를 채취하여 각종 실내시험을 실시하고, 지역, 암종 및 구성 성분에 따른 물리 역학적 특성(단위중량, 비중, 공극률, 자갈함량, 실트/점토 함량, 점토광물 함량, 내부마찰각 및 점착력)을 분석하였다. 암종별 물리 역학적 특성은 편마암의 경우 단위중량($17.1kN/m^3$)과 비중(2.73)에서 가장 높은 중앙값을 보이며, 화강암은 공극률(45.5%), 편암은 자갈함량(20.0 wt.%)과 점착력(38.1 kPa), 천매암은 실트/점토 함량(54.4 wt.%), 점토광물 함량(37.7 wt.%)과 내부마찰각($38.2^{\circ}$)에서 가장 높은 중앙값을 보인다. 구성 성분별 물리 역학적 특성은 단층점토가 공극률과 실트/점토 함량을 제외한 모든 인자에서 파쇄암 및 손상대보다 낮은 값을 보이는 것으로 나타났다.

• 대한기계학회논문집A
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• 제36권7호
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• pp.813-822
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• 2012

LCD 생산라인의 공정 로봇에서 방사되는 비정상 작동 소음은 로봇의 결함 탐지에 사용된다. 이 신호의 장점은 상대적으로 낮은 민감도에 비해 단지 마이크로폰을 이용하여 다수의 결함을 확인할 수 있는 것이다. 결함요소 추출을 위한 웨이브렛 변환(WPT)과 불량의 분류를 위한 인공신경망 회로(ANN)이 본 논문에서 사용되었다. 결과적으로, 비정상 작동 소음이 기계요소의 결함 진단에 효율적으로 사용될 수 있다.

• 한국자동차공학회논문집
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• 제20권1호
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• pp.1-7
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• 2012

The brake-by-wire technology is a new automotive chassis system that allows standard braking operations by electronic components with lighter weights and faster response. The brake-by-wire units such as EMB (Electro-Mechanical Brake) are controlled by electronic sensors and actuators and, thus, the fault diagnosis is essential for implementation. In this study, a model-based fault diagnosis system is developed for the sensors based on the analytical redundancy method. The fault detection algorithm is verified in simulations for various faulty cases. A test bench is built including the EMB unit and the performance of the proposed fault diagnosis system is evaluated through the experiment.