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System identification of a building structure using wireless MEMS and PZT sensors
Kim, Hongjin,Kim, Whajung,Kim, Boung-Yong,Hwang, Jae-Seung Techno-Press 2008 Structural Engineering and Mechanics, An Int'l Jou Vol.30 No.2
A structural monitoring system based on cheap and wireless monitoring system is investigated in this paper. Due to low-cost and low power consumption, micro-electro-mechanical system (MEMS) is suitable for wireless monitoring and the use of MEMS and wireless communication can reduce system cost and simplify the installation for structural health monitoring. For system identification using wireless MEMS, a finite element (FE) model updating method through correlation with the initial analytical model of the structure to the measured one is used. The system identification using wireless MEMS is evaluated experimentally using a three storey frame model. Identification results are compared to ones using data measured from traditional accelerometers and results indicate that the system identification using wireless MEMS estimates system parameters with reasonable accuracy. Another smart sensor considered in this paper for structural health monitoring is Lead Zirconate Titanate (PZT) which is a type of piezoelectric material. PZT patches have been applied for the health monitoring of structures owing to their simultaneous sensing/actuating capability. In this paper, the system identification for building structures by using PZT patches functioning as sensor only is presented. The FE model updating method is applied with the experimental data obtained using PZT patches, and the results are compared to ones obtained using wireless MEMS system. Results indicate that sensing by PZT patches yields reliable system identification results even though limited information is available.
Hongjin Shim,Dae Ryong Kang,Hye Sim Kim,Ji Young Jang,Ou-Hyen Kim,Kiyoung Kim,Un Young Choi,Ko Ji Wool,Keum Seok Bae 대한외상중환자외과학회 2024 Journal of Acute Care Surgery Vol.14 No.1
Purpose: We sought to assess mortality trends in chest-abdominal trauma patients, before and after theimplementation of the Project Supporting Establishment of Trauma Centers (PSETC) in the Republic ofKorea. Methods: Data from the National Health Insurance Service claims database between 2009 to 2017 wereanalyzed. Patients with chest-abdominal trauma were defined as those with relevant main diagnosiscodes and claims for emergency medical management fees. Mortality and cumulative data were analyzedfor each year to compare mortality before and after the establishment of regional trauma centers acrossKorea (2014). Results: In total, 29,127 patients were included in the analysis. While the annual incidence of trauma-related chest-abdominal injuries increased, mortalities decreased. In particular, the trauma incidencerate among patients over 50 years increased during the study period. Mortalities at trauma centers didnot change year by year after the PSETC. Before and after 2014, when trauma centers operated underthe PSETC, mortalities decreased [trauma cases before the PSETC; n = 14,321 (mortality 5.61), after thePSETC; n = 14,806 (mortality 4.96)]. Conclusion: The number of patients treated for chest-abdominal injuries increased from 2009 to 2017 inKorea, whereas mortalities decreased over the same period.
Kim, HongJin,Kim, SoYoung,Lee, Kang-Yoon The Korean Institute of Power Electronics 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.6
This paper presents a secondary-side, dual-mode feedback LLC resonant controller IC with dynamic PWM dimming for LED backlight units. In order to reduce the cost, master and slave outputs can be generated simultaneously with a single LLC resonant core based on dual-mode feedback topologies. Pulse Frequency Modulation (PFM) and Pulse Width Modulation (PWM) schemes are used for the master stage and slave stage, respectively. In order to guarantee the correct dual feedback operation, Phased-Locked Loop (PLL)-based automatic duty control circuit is proposed in this paper. The chip is fabricated using $0.35{\mu}m$ Bipolar-CMOS-DMOS (BCD) technology, and the die size is $2.5mm{\times}2.5mm$. The frequency of the gate driver (GDA/GDB) in the clock generator ranges from 50 to 425 kHz. The current consumption of the LLC resonant controller IC is 40 mA for a 100 kHz operation frequency using a 15 V supply. The duty ratio of the slave stage can be controlled from 40% to 60% independent of the frequency of the master stage.