http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Relative baseline features for impedance-based structural health monitoring
Jung, Hwee Kwon,Jo, HyeJin,Park, Gyuhae,Mascarenas, David L,Farrar, Charles R SAGE Publications 2014 Journal of intelligent material systems and struct Vol.25 No.18
<P>Various experimental studies have demonstrated that an impedance-based method is an effective means of structural damage detection. Using the self-sensing and active-sensing capabilities of piezoelectric materials, the electromechanical impedance response can be monitored to provide a qualitative indication of the overall health of a structure. In this article, two new signal processing tools for the impedance method are described in order to improve the damage detection capability and to reduce the amount of data to process for structural health assessment. The first approach is to instantaneously correlate the impedance data between different sensor sets, as opposed to be correlated to pre-stored baseline data. Another approach is to use the pre-defined parameter of impedance data to establish a generalized baseline for bolted joint monitoring. These approaches could reduce the number of data sets and could be efficiently used for low-power impedance devices. The proposed signal processing techniques are applied to several experimental structures, and the efficiency in damage detection is demonstrated.</P>
Hwee Kwon Jung(정휘권),Myung Jun Lee(이명준),Jun Young Jeon(전준영),Gyuhae Park(박규해),To Kang(강토),Soon Woo Han(한순우) 한국소음진동공학회 2016 한국소음진동공학회 학술대회논문집 Vol.2016 No.4
Condition Monitoring(CM) methods encounter a big data problem in processing the data collected through dense sensor networks with a high sampling rate. For this reason, compressive sensing technique has been introduced to improve efficiency and scalability of todays CM procedures parallel to data acquisition improvement. In this study, Compressive sensing approach for condition monitoring is proposed to demonstrate efficiency in handling a large amount of data. For experiments, a built-in system was used for condition monitoring of a rotating system. During the experiments, all data were sampled with compressive sensing to obtain compressed data. Then we had performed condition monitoring only using compressed data without the reconstruction process. Experimental results show that the proposed method could effectively improve the speed of data processing and reduce energy consumption of sensing networks.
Structural impact detection with vibro-haptic interfaces
Jung, Hwee-Kwon,Park, Gyuhae,Todd, Michael D IOP 2016 Smart materials & structures Vol.25 No.7
<P>This paper presents a new sensing paradigm for structural impact detection using vibro-haptic interfaces. The goal of this study is to allow humans to ‘feel’ structural responses (impact, shape changes, and damage) and eventually determine health conditions of a structure. The target applications for this study are aerospace structures, in particular, airplane wings. Both hardware and software components are developed to realize the vibro-haptic-based impact detection system. First, L-shape piezoelectric sensor arrays are deployed to measure the acoustic emission data generated by impacts on a wing. Unique haptic signals are then generated by processing the measured acoustic emission data. These haptic signals are wirelessly transmitted to human arms, and with vibro-haptic interface, human pilots could identify impact location, intensity and possibility of subsequent damage initiation. With the haptic interface, the experimental results demonstrate that human could correctly identify such events, while reducing false indications on structural conditions by capitalizing on human’s classification capability. Several important aspects of this study, including development of haptic interfaces, design of optimal human training strategies, and extension of the haptic capability into structural impact detection are summarized in this paper.</P>
L-형상 압전체 센서 배열을 이용한 충격 및 손상 탐지 기법 개발
정휘권(Hwee-Kwon Jung),이명준(Myung-Jun Lee),박규해(Gyuhae Park) 한국비파괴검사학회 2014 한국비파괴검사학회지 Vol.34 No.5
항공기 구조물 표면에 발생하는 외부 충격은 크랙과 같은 손상을 발생시킬 수 있으며 이는 차후 큰 결함을 야기하기 때문에 충격과 손상을 탐지하고 위치를 추정하는 것은 구조 안정성 모니터링에 있어 중요한 부분이다. 본 연구에서는 능동, 수동 센싱기법을 조합한 L-형상 압전체 센서 배열을 사용하여 충격과 손상을 탐지할 수 있는 기법을 개발하였다. 수동 센싱기법으로 1개 센서군 당 3개의 센서를 L-형상으로 배치하여 충격 발생 각도를 추정하고 2개의 센서군을 사용하여 충격위치를 탐지하는 방법을 도입하였다. 이 수동 센싱기법을 유도초음파 기반의 능동 센싱기법에 확대 적용하여 동일한 압전소자로 충격 탐지와 더불어 손상을 탐지할 수 있는 방법을 개발하였다. 이 기법은 방향에 따른 파동의 속도 변화와 같은 구조물에 대한 정보 없이도 위치 추정이 가능하여 비등방성 구조 내에서도 정확한 충격 및 손상 위치 정보를 얻을 수 있다. 개발된 기법을 날개 형태 구조물 및 CFRP 판에 적용하여 실험적으로 정확한 충격 및 손상 위치를 추정할 수 있음을 증명하였다. This paper presents a method that integrates passive and active-sensing techniques for the structural health monitoring of plate-like structures. Three piezoelectric transducers are deployed in a L-shape to detect and locate an impact event by measuring and processing the acoustic emission data. The same sensor arrays are used to estimate the subsequent structural damage using guided waves. Because this method does not require a prior knowledge of the structural parameters, such as the wave velocity profile in various directions, accurate results could be achieved even on anisotropic or curved plates. A series of experiments was performed on plates, including a spar-wing structure, to demonstrate the capability of the proposed method. The performance was also compared to that of traditional approaches and the superior capability of the proposed method was experimentally demonstrated.
특수목적 차량용 샤시의 내구성능 평가를 위한 등가하중 신호 개발
정휘권(Hwee Kwon Jung),박규해(Gyuhae Park),강지상(Jisang Kang),고환규(Hwan Kyu Kho),박병식(Byung Sik Park),정명철(Myungchuel Jung),정길성(Gilsung Jung) 한국자동차공학회 2018 한국자동차공학회 지부 학술대회 논문집 Vol.2018 No.5
Assessment of durability is an essential in early stages of development. In these stages, tuning parts and geometry of a vehicle are not determined. In addition there are no available physical prototypes. Therefore, numerical durability analysis with a reasonable load signal is required. We propose several techniques to produce an equivalent load signal for numerical durability analysis. The acceleration signals are measured through a prototype vehicle test on various road conditions and converted into force and displacement signals, respectively. The signals are then refined and a representative segment of the signal is selected by considering the statistical characteristics, frequency component and fatigue damage. Finally the equivalent load signals are produced from the selected representative signal based on a time correlated damage editing method. For validation of the proposed techniques, comparison of the signal characteristics and a series of numerical analysis are planed to be carried out.
수위변화에 따른 파이프 시스템의 진동 특성 변화에 대한 연구
정휘권(Hwee Kwon Jung),김종윤(Jong yoon Kim),박규해(Gyuhae Park) 한국소음진동공학회 2013 한국소음진동공학회 학술대회논문집 Vol.2013 No.10
This paper presents vibration testing, control, and finite element analysis of a piping system, which is subjected to the changes in fluid levels. Nuclear power plants typically employ a cooling system that uses sea water. These systems are subjected to dynamic characteristic changes caused by sea-level variations, which introduces failures of cooling system components. Therefore in this study, analytical and experimental studies were performed to understand the effect of sea-level changes on the dynamic characteristics of piping systems. It was shown that, as the sea-level increases, pipe’s natural frequencies decreases in relation to its mode shape. A 1/14 scale model was also built to compare the results obtained by the analytical study. A good agreement between experiment and analytical studies were observed. Finally, an on-line resonant frequency identification system was proposed and developed, which utilizes piezoelectric transducers as sensors and actuators, in order to avoid catastrophic failure of piping systems.