http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Solar-powered multi-scale sensor node on Imote2 platform for hybrid SHM in cable-stayed bridge
Duc-Duy Ho,김정태,Khac-Duy Nguyen,홍동수,이소영,신성우,윤정방,Masanobu Shinozuka,Po-Young Lee 국제구조공학회 2012 Smart Structures and Systems, An International Jou Vol.9 No.2
In this paper, solar-powered, multi-scale, vibration-impedance sensor node on Imote2 platform is presented for hybrid structural health monitoring (SHM) in cable-stayed bridge. In order to achieve the objective, the following approaches are proposed. Firstly, vibration- and impedance-based hybrid SHM methods are briefly described. Secondly, the multi-scale vibration and impedance sensor node on Imote2- platform is presented on the design of hardware components and embedded software for vibration- and impedance-based SHM. In this approach, a solar-powered energy harvesting is implemented for autonomous operation of the smart sensor nodes. Finally, the feasibility and practicality of the smart sensor-based SHM system is evaluated on a full-scale cable-stayed bridge, Hwamyung Bridge in Korea. Successful level of wireless communication and solar-power supply for smart sensor nodes are verified. Also, vibration and impedance responses measured from the target bridge which experiences various weather conditions are examined for the robust long-term monitoring capability of the smart sensor system.
Duc-Duy Ho,Dong-Soo Hong,Jeong-Tae Kim 한국비파괴검사학회 2010 한국비파괴검사학회지 Vol.30 No.6
This paper presents a nondestructive evaluation approach for system identification (SID) of real railway bridges using field vibration test results. First, a multi-phase SID scheme designed on the basis of eigenvalue sensitivity concept is presented. Next, the proposed multi-phase approach is evaluated from field vibration tests on a real railway bridge (Wondongcheon bridge) located in Yangsan, Korea. On the steel girder bridge, a few natural frequencies and mode shapes are experimentally measured under the ambient vibration condition. The corresponding modal parameters are numerically calculated from a three-dimensional finite element (FE) model established for the target bridge. Eigenvalue sensitivities are analyzed for potential model-updating parameters of the FE model. Then, structural subsystems are identified phase-by-phase using the proposed model-updating procedure. Based on model-updating results, a baseline model and a nondestructive evaluation of test bridge are identified.
Duc Duy Le,Soon‑Ku Hong,Trong Si Ngo,Jeongkuk Lee,Yun Chang Park,홍순익,나영상 대한금속·재료학회 2018 METALS AND MATERIALS International Vol.24 No.6
Microstructural properties of as-grown and annealed CoCrFeMnNi high entropy alloy (HEA) oxynitride thin films wereinvestigated. The CoCrFeMnNi HEA oxynitride thin film was grown by magnetron sputtering method using an air gas, andannealed under the argon plus air flow for 5 h at 800 °C. The as-grown film was homogeneous and uniform composed ofnanometer-sized crystalline regions mixed with amorphous-like phase. The crystalline phase in the as-grown film was facecentered cubic structure with the lattice constant of 0.4242 nm. Significant microstructural changes were observed afterthe annealing process. First, it was fully recrystallized and grain growth happened. Second, Ni-rich region was observed innanometer-scale range. Third, phase change happened and it was determined to be Fe3O4spinel structure with the latticeconstant of 0.8326 nm. Hardness and Young’s modulus of the as-grown film were 4.1 and 150.5 GPa, while those were 9.4and 156.4 GPa for the annealed film, respectively.
Damage detection in beam-type structures via PZT’s dual piezoelectric responses
Khac-Duy Nguyen,김정태,Duc-Duy Ho 국제구조공학회 2013 Smart Structures and Systems, An International Jou Vol.11 No.2
In this paper, practical methods to utilize PZT’s dual piezoelectric effects (i.e., dynamic strain and electro-mechanical (E/M) impedance responses) for damage detection in beam-type structures are presented. In order to achieve the objective, the following approaches are implemented. Firstly, PZT material’s dual piezoelectric characteristics on dynamic strain and E/M impedance are investigated. Secondly, global vibration-based and local impedance-based methods to detect the occurrence and the location of damage are presented. Finally, the vibration-based and impedance-based damage detection methods using the dual piezoelectric responses are evaluated from experiments on a lab-scaled beam for several damage scenarios. Damage detection results from using PZT sensor are compared with those obtained from using accelerometer and electric strain gauge.
Impedance-based damage monitoring of steel column connection: numerical simulation
Ho, Duc-Duy,Ngo, Thanh-Mong,Kim, Jeong-Tae Techno-Press 2014 Structural monitoring and maintenance Vol.1 No.3
This study has been motivated to evaluate the practicality of numerical simulation of impedance monitoring for damage detection in steel column connection. In order to achieve the objective, the following approaches are implemented. Firstly, the theory of electro-mechanical (E/M) impedance responses and impedance-based damage monitoring method are outlined. Secondly, the feasibility of numerical simulation of impedance monitoring is verified for several pre-published experimental examples on steel beams, cracked aluminum beams, and aluminum round plates. Undamaged and damaged steel and aluminum beams are simulated to compare to experimental impedance responses. An aluminum round plate with PZT patch in center is simulated to investigate sensitive range of impedance responses. Finally, numerical simulation of the impedance-based damage monitoring is performed for a steel column connection in which connection bolts are damaged. From the numerical simulation test, the applicability of the impedance-based monitoring to the target steel column connection can be evaluated.
Ho, Duc-Duy,Hong, Dong-Soo,Kim, Jeong-Tae The Korean Society for Nondestructive Testing 2010 한국비파괴검사학회지 Vol.30 No.6
This paper presents a nondestructive evaluation approach for system identification (SID) of real railway bridges using field vibration test results. First, a multi-phase SID scheme designed on the basis of eigenvalue sensitivity concept is presented. Next, the proposed multi-phase approach is evaluated from field vibration tests on a real railway bridge (Wondongcheon bridge) located in Yangsan, Korea. On the steel girder bridge, a few natural frequencies and mode shapes are experimentally measured under the ambient vibration condition. The corresponding modal parameters are numerically calculated from a three-dimensional finite element (FE) model established for the target bridge. Eigenvalue sensitivities are analyzed for potential model-updating parameters of the FE model. Then, structural subsystems are identified phase-by-phase using the proposed model-updating procedure. Based on model-updating results, a baseline model and a nondestructive evaluation of test bridge are identified.
Le, Duy Duc,Kim, Dong Yeob,Hong, Soon-Ku Materials Research Society of Korea 2014 한국재료학회지 Vol.24 No.5
Aluminum nitride(AlN) films were grown on the C-face and on the Si-face of (0001) silicon carbide(SiC) substrates using plasma-assisted molecular-beam epitaxy(PA-MBE). This study was focused on first-stage growth manipulation prior to the start of AlN growth. Al pre-exposure, N-plasma pre-exposure, and simultaneous exposure(Al and N-plasma) procedures were used in the investigation. In addition, substrate polarity and, first-stage growth manipulation strongly affected the growth and properties of the AlN films. Al pre-exposure on the C-face and on the Si-face of SiC substrates prior to initiation of the AlN growth resulted in the formation of hexagonal hillocks on the surface. However, crack formation was observed on the C-face of SiC substrates without Al pre-exposure. X-ray rocking-curve measurements revealed that the AlN epilayers grown on the Si-face of the SiC showed relatively lower tilt and twist mosaic than did the epilayers grown on the C-face of the SiC. The results from the investigations reported in this paper indicate that the growth conditions on the Si-face of the SiC without Al pre-exposure was highly preferred to obtain the overall high-quality AlN epilayers formed using PA-MBE.
Multi-Phase Model Update for System Identification of PSC Girders under Various Prestress Forces
Ho, Duc-Duy,Hong, Dong-Soo,Kim, Jeong-Tae Computational Structural Engineering Institute of 2010 한국전산구조공학회논문집 Vol.23 No.6
This paper presents a multi-phase model update approach for system identification of prestressed concrete (PSC) girders under various prestress forces. First, a multi-phase model update approach designed on the basis of eigenvalue sensitivity concept is newly proposed. Next, the proposed multi-phase approach is evaluated from controlled experiments on a lab-scale PSC girder for which forced vibration tests are performed for a series of prestress forces. On the PSC girder, a few natural frequencies and mode shapes are experimentally measured for the various prestress forces. The corresponding modal parameters are numerically calculated from a three-dimensional finite element (FE) model which is established for the target PSC girder. Eigenvalue sensitivities are analyzed for potential model-updating parameters of the FE model. Then, structural subsystems are identified phase-by-phase using the proposed model update procedure. Based on model update results, the relationship between prestress forces and model-updating parameters is analyzed to evaluate the influence of prestress forces on structural subsystems.
Solar-powered multi-scale sensor node on Imote2 platform for hybrid SHM in cable-stayed bridge
Ho, Duc-Duy,Lee, Po-Young,Nguyen, Khac-Duy,Hong, Dong-Soo,Lee, So-Young,Kim, Jeong-Tae,Shin, Sung-Woo,Yun, Chung-Bang,Shinozuka, Masanobu Techno-Press 2012 Smart Structures and Systems, An International Jou Vol.9 No.2
In this paper, solar-powered, multi-scale, vibration-impedance sensor node on Imote2 platform is presented for hybrid structural health monitoring (SHM) in cable-stayed bridge. In order to achieve the objective, the following approaches are proposed. Firstly, vibration- and impedance-based hybrid SHM methods are briefly described. Secondly, the multi-scale vibration and impedance sensor node on Imote2-platform is presented on the design of hardware components and embedded software for vibration- and impedance-based SHM. In this approach, a solar-powered energy harvesting is implemented for autonomous operation of the smart sensor nodes. Finally, the feasibility and practicality of the smart sensor-based SHM system is evaluated on a full-scale cable-stayed bridge, Hwamyung Bridge in Korea. Successful level of wireless communication and solar-power supply for smart sensor nodes are verified. Also, vibration and impedance responses measured from the target bridge which experiences various weather conditions are examined for the robust long-term monitoring capability of the smart sensor system.