scholarly journals Structural Performance Assessment Based on Statistical and Wavelet Analysis of Acceleration Measurements of a Building during an Earthquake

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
Mosbeh R. Kaloop ◽  
Jong Wan Hu ◽  
Mohamed A. Sayed ◽  
Jiyoung Seong
Keyword(s):  
Wavelet Analysis ◽  
Health Monitoring ◽  
Energy Content ◽  
Dominant Frequency ◽  
Wavelet Spectrum ◽  
Structural Performance ◽  
Frequency Range ◽  
Recording Point ◽  
National University ◽  
Seoul National University

This study introduces the analysis of structural health monitoring (SHM) system based on acceleration measurements during an earthquake. The SHM system is applied to assess the performance investigation of the administration building in Seoul National University of Education, South Korea. The statistical and wavelet analysis methods are applied to investigate and assess the performance of the building during an earthquake shaking which took place on March 31, 2014. The results indicate that (1) the acceleration, displacement, and torsional responses of the roof recording point on the top floor of the building are more dominant in theXdirection; (2) the rotation of the building has occurred at the base recording point; (3) 95% of the energy content of the building response is shown in the dominant frequency range (6.25–25 Hz); (4) the wavelet spectrum illustrates that the roof vibration is more obvious and dominant during the shaking; and (5) the wavelet spectrum reveals the elasticity responses of the structure during the earthquake shaking.

scholarly journals Digital Processing of Seismic Data from Open-Pit Mining Blasts

2021 ◽  
Vol 11 (1) ◽  
pp. 383
Author(s):  
Natalia Koteleva ◽  
Ilia Frenkel
Keyword(s):  
Experimental Data ◽  
Wavelet Analysis ◽  
Correlation Dimension ◽  
Low Frequency ◽  
Digital Processing ◽  
Dominant Frequency ◽  
Open Pit ◽  
Open Pit Mining ◽  
Frequency Range ◽  
Amplitude Dependency

This article describes an approach of mathematical processing of signals (seismograms) from five blasthole charges from experimental blasting, each 3 m deep, with equal explosive weight (1 kg), and equidistant (3 m) from one other. The seismic explosive waves were measured at a 13 to 25 m distance. This article provides spectral analysis, wavelet analysis, and fractal analysis results. It defines the dependence of dominant frequency and amplitude on the distance to the blast center. According to the experimental data, the dominant frequency is calculated as y = 1.0262x0.2622 and the amplitude dependency as y = 18.139x−2.276. Furthermore, the analysis shows that 80% of the entire signal is concentrated in half the area of frequency range, i.e., the low frequency zone is of the most interest. This research defines the dependence of distance on the energy value of signal wavelet analysis. It is demonstrated that, according to the experimental data, the 12th frequency range is closely correlated with the distance values. This article gives the definitions of entropy, correlation dimension, and predictability time. This experiment shows that entropy and correlation dimension decrease but predictability time increases when the distance to the blast center increases. This article also describes the method for determining optimal drilling and blasting parameters, and concludes with the possibility of applying the analytical results to predicting and enhancing drilling and blasting operations.

scholarly journals Predictors of cervical myelopathy and hydrocephalus in young children with achondroplasia

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Youngbo Shim ◽  
Jung Min Ko ◽  
Tae-Joon Cho ◽  
Seung‐Ki Kim ◽  
Ji Hoon Phi
Keyword(s):  
Magnetic Resonance Imaging ◽  
Young Children ◽  
Cervical Myelopathy ◽  
Treatment Method ◽  
Foramen Magnum ◽  
Resonance Imaging ◽  
Timely Manner ◽  
Frontal Horn ◽  
National University ◽  
Seoul National University

Abstract Background Cervical myelopathy and hydrocephalus occasionally occur in young children with achondroplasia. However, these conditions are not evaluated in a timely manner in many cases. The current study presents significant predictors for cervical myelopathy and hydrocephalus in young children with achondroplasia. Methods A retrospective analysis of 65 patients with achondroplasia who visited Seoul National University Children’s Hospital since 2012 was performed. The patients were divided into groups according to the presence of cervical myelopathy and hydrocephalus, and differences in foramen magnum parameters and ventricular parameters by magnetic resonance imaging between groups were analyzed. Predictors for cervical myelopathy and hydrocephalus were analyzed, and the cut-off points for significant ones were calculated. Results The group with cervical myelopathy showed foramen magnum parameters that indicated significantly lower cord thickness than in the group without cervical myelopathy, and the group with hydrocephalus showed significantly higher ventricular parameters and ‘Posterior indentation’ grade than the group without hydrocephalus. ‘Cord constriction ratio’ (OR 5199.90, p = 0.001) for cervical myelopathy and ‘Frontal horn width’ (OR 1.14, p = 0.001) and ‘Posterior indentation’ grade (grade 1: OR 9.25, p = 0.06; grade 2: OR 18.50, p = 0.01) for hydrocephalus were significant predictors. The cut-off points for cervical myelopathy were ‘Cord constriction ratio’ of 0.25 and ‘FM AP’ of 8 mm (AUC 0.821 and 0.862, respectively) and ‘Frontal horn width’ of 50 mm and ‘Posterior indentation’ grade of 0 (AUC 0.788 and 0.758, respectively) for hydrocephalus. Conclusion ‘Cord constriction ratio’ for cervical myelopathy and ‘Frontal horn width’ and ‘Posterior indentation’ grade for hydrocephalus were significant predictors and may be used as useful parameters for management. ‘Posterior indentation’ grade may also be used to determine the treatment method for hydrocephalus.

scholarly journals Components of Metabolic Syndrome in Korean Adults: A Hospital-Based Cohort at Seoul National University Bundang Hospital

2019 ◽  
Vol 28 (2) ◽  
pp. 118-128 ◽  
Author(s):  
Soo Lim ◽  
Se Hee Min ◽  
Ji Hyun Lee ◽  
Lee Kyung Kim ◽  
Dong-Hwa Lee ◽  
...  
Keyword(s):  
Metabolic Syndrome ◽  
Korean Adults ◽  
National University ◽  
Seoul National University

Climate related variations in atmospheric nitrous oxide concentration during the Mid- to Late Holocene

2021 ◽  
Author(s):  
Syed Azharuddin ◽  
Jinho Ahn ◽  
Yeongjun Ryu ◽  
Ed Brook
Keyword(s):  
Nitrous Oxide ◽  
Late Holocene ◽  
Ice Core ◽  
Progressive Increase ◽  
La Niña ◽  
La Nina ◽  
National University ◽  
Seoul National University ◽  
Sudden Decrease ◽  
Nitrous Oxide Concentration

<p>Nitrous oxide (N<sub>2</sub>O) is an important greenhouse gas with sources that respond to the biogeochemical processes on land and ocean. The major sources of atmospheric N<sub>2</sub>O are nitrification and denitrification occurring in terrestrial soils and the ocean. Here we present a new high-resolution atmospheric N<sub>2</sub>O record obtained from South Pole Ice (SPICE) core site covering the Mid- to Late Holocene (since ~5.5 ka). The N<sub>2</sub>O analysis was performed in a specialised wet extraction facility installed at Seoul National University that used small ice samples (<20 g) to yield a high precision (average standard deviation of ~1ppb) record. The new N<sub>2</sub>O data agree well with existing records on the millennial scale and reveal new details on the multi-centennial scale. Our results show a progressive increase in atmospheric N<sub>2</sub>O during 5.5 to 3.2 ka which correlates well with the increase of marine denitrification around the Arabian Sea (AS) and Peru-Chile Margin (PCM) as well as Indian monsoon precipitation around the same period. A local minimum in N<sub>2</sub>O is observed around 2.8 ka, possibly related to a sudden decrease in Western Tropical South (WTS) Pacific sea surface temperature and increased La-Nina like conditions which may have supressed denitrification along PCM. These conditions may have further influenced the monsoons and reduced denitrification in land soils. Our record also shows a local N<sub>2</sub>O maximum around 2.2 ka which may correspond to relaxed La-Nina like conditions around WTS Pacific. Subsequently, the N<sub>2</sub>O further dropped to attain a pronounced minimum around 1.4 ka. Similar N<sub>2</sub>O minima are also observed in Styx (Antarctica) and  NEEM (Greenland) ice core records, demonstrating the robustness of the signals.</p>

scholarly journals Screening for early detection of lung cancer: results from Seoul National University Hospital.

1991 ◽  
Vol 38 (2) ◽  
pp. 119-127
Author(s):  
Yong Chol Han ◽  
Chul Gyu Yoo ◽  
Young Whan Kim ◽  
Sung Koo Han ◽  
Young Soo Shim ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Early Detection ◽  
University Hospital ◽  
National University ◽  
Seoul National University
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