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Retrieving the Time History of Displacement from Measured Acceleration Signal
Sangbo Han 대한기계학회 2003 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.17 No.2
It is intended to retrieve the time history of displacement from measured accelaeration signal. In this study, the word retrieving means reconstructing the time history of original displacement signal from already measured acceleration signal not just extracting various information using relevant signal processing techniques. Unlike extracting required information from the signal, there are not many options to apply to retrieve the time history of displacement signal, once the acceleration signal is measured and recorded with given sampling rate.There are two methods, in general, to convert measured acceleration signal into displacement signal . One is directly integrating the acceleration signal in time domain. The other is dividing the Fourier transformed acceleration signal by the scale factor of -w² and taking the inverse Fourier transform of it. It turned out both the methods produced a significant amount of errors depending on the sampling resolution in time and frequency domain when digitizing the acceleration signals. A simple and effective way to convert the time history of acceleration signal into the time history of displacement signal without significant errors is studied here with the analysis on the errors involved in the conversion process.
Sangbo Park,박성훈,김수현,현승균,이종무 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.65 No.9
Nb2O5 nanosensors showing good sensing performances toward hydrogen and oxygen at hightemperatures have been reported several times, but high-performance room-temperature Nb2O5gas sensors have not been reported to date. Pd-Nb2O5 nanorods were synthesized by using thermaloxidation of a Nb foil, followed by wet chemical coating of Pd under UV illumination. The responsesof multiple-networked Pd-Nb2O5 nanorod sensors to 10,000 ppm of hydrogen at room temperaturewere 218% and 496%, respectively. Responses obtained in this study were far higher than thatto 2,000 ppm of H2 obtained previously at the same temperature by using Pt/Nb2O5 Schottkydiodesensors. These results suggest that multiple-networked 1D nanostructure sensors, whichcan be fabricated more easily, are superior in H2-gas-sensing properties to Schottky-diode-typenanostructure sensors, which require precise techniques to connect the nanostructures. The originof the enhanced sensing properties of the Pd-decorated Nb2O5 nanorods toward hydrogen is alsodiscussed.
Robust Adaptive Control for a Class of Nonlinear Systems with Complex Uncertainties
Sangbo Seo,Juhoon Back,Hyungbo Shim,Jin H. Seo 대한전기학회 2009 Journal of Electrical Engineering & Technology Vol.4 No.2
This paper considers a robust adaptive stabilization problem for a class of uncertain nonlinear systems which include an unknown virtual control coefficient, an unknown constant parameter, and a time-varying disturbance whose bound is unknown. We propose a new estimator for an unknown virtual control coefficient and present a robust adaptive backstepping design procedure which results in a smooth state feedback control law, a new two-dimensional parameter update law, and a C¹ Lyapunov function which is positive definite and proper.
Manganese speciation in Mn-rich CaCO<sub>3</sub>: A density functional theory study
Son, Sangbo,Newton, Aric G.,Jo, Kyoung-nam,Lee, Jin-Yong,Kwon, Kideok D. Pergamon Press 2019 Geochimica et cosmochimica acta Vol.248 No.-
<P><B>Abstract</B></P> <P>The manganese content of aragonitic bivalve shells is a potential archival indicator of temporal Mn bioavailability in aquatic environments. The Mn speciation mechanism in biogenic aragonite minerals remains elusive because the analog is challenging to synthesize, and the metastable phase has yet to be fully resolved experimentally. In this study, we performed density functional theory (DFT) computations of hypothetical Mn-doped aragonite to examine its local coordination structure and thermodynamic and electronic properties. Our DFT calculations reproduced the experimental crystal structures and solubility product constants (<I>K</I> <SUB>sp</SUB>) of Mn-doped calcite. The magnetic moment of Mn was close to 5 <I>μ</I> <SUB>B</SUB> in both Mn-doped calcite and Mn-doped aragonite (Ca<SUB>1−</SUB> <I> <SUB>x</SUB> </I>Mn<I> <SUB>x</SUB> </I>CO<SUB>3</SUB>). The calculated <I>K</I> <SUB>sp</SUB> of Mn-doped aragonite was higher than that of Mn-doped calcite and increased with Mn content, indicative of the unfavorable coprecipitation of Mn with the aragonite phase. We found that the incorporation of a small mole fraction of Mn into aragonite created significant structural distortion around the Mn site, resulting in mixed coordination numbers of Mn (mainly five and seven). Valence-to-core X-ray emission spectroscopy (XES) measurements are useful in determining the coordination environment of Mn complexes. We calculated theoretical XES spectra, with a 1<I>s</I> core hole in Mn, for Mn-doped calcite and four versions of Mn-doped aragonite. The Boltzmann-averaged spectrum for different coordination numbers in Mn-doped aragonite was akin to an experimental XES spectrum of aragonitic bivalve shells. The energy position of the K<I>β</I> <SUB>2,5</SUB> band was calculated to be insensitive to Mn speciation in CaCO<SUB>3</SUB>; however, the band intensity was relatively sensitive to Mn speciation. The XES spectrum intensity decreased exponentially with increasing Mn–O distance. This quantitative XES relationship we report can reduce uncertainties in the spectral interpretation due to the absence of an Mn-doped aragonite reference spectrum.</P>
Clinical Implementation of Targeted Gene Sequencing for Malformation of Cortical Development
Lee, Sangbo,Kim, Se Hee,Kim, Borahm,Lee, Seung-Tae,Choi, Jong Rak,Kim, Heung Dong,Lee, Joon Soo,Kang, Hoon-Chul Elsevier 2020 Pediatric neurology Vol.103 No.-
<P><B>Abstract</B></P> <P><B>Background</B></P> <P>Malformations of cortical development comprise phenotypically heterogeneous conditions, and the diagnostic value of genetic testing in blood still remains to be elucidated. We used targeted gene sequencing to identify malformations of cortical development caused by germline mutations and characteristics associated with pathogenic mutations.</P> <P><B>Methods</B></P> <P>A total of 81 patients with malformations of cortical development were included. Genomic DNA was isolated from peripheral blood. Ninety-six genes were assessed using a targeted next-generation sequencing panel. Single-nucleotide variants and exonic and chromosomal copy number variations were examined with our customized pipeline.</P> <P><B>Results</B></P> <P>Genetic causes were identified from blood in 19 (23.5%) patients with malformations of cortical development; 14 patients had pathogenic or likely pathogenic single-nucleotide variants in seven genes, including <I>DCX</I> (n = 5), <I>DEPDC5</I> (n = 2), <I>PAFAH1B1</I> (n = 3), <I>TUBA1A</I> (n = 1), <I>TUBA8</I> (n = 1), <I>TUBB2B</I> (n = 1), and <I>TUBB3</I> (n = 1). Five patients had pathogenic copy number variations. Multifocal involvement of the lesion (tangential distribution, <I>P</I> < 0.001) and concurrent involvement of multiple structures such as the cortex, white matter, and ventricle (radial distribution, <I>P</I> = 0.003) were more commonly found in patients with identified genetic causes. Intellectual disability was also more commonly associated with pathogenic mutations (<I>P =</I> 0.048). In a multivariable regression analysis, both tangential and radial radiological distribution of malformations of cortical development were independently associated with positive germline test results.</P> <P><B>Conclusion</B></P> <P>We identified germline mutations in almost one-fourth of our patients with malformations of cortical development by using targeted gene sequencing. Germline abnormalities were more likely found in patients who had multifocal malformations of cortical development.</P>
Retrieving the Time History of Displacement from Measured Acceleration Signal
Han, Sangbo The Korean Society of Mechanical Engineers 2003 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.17 No.2
It is intended to retrieve the time history of displacement from measured acceleration signal. In this study, the word retrieving means reconstructing the time history of original displacement signal from already measured acceleration signal not just extracting various information using relevant signal processing techniques. Unlike extracting required information from the signal, there are not many options to apply to retrieve the time history of displacement signal, once the acceleration signal is measured and recorded with given sampling rate. There are two methods, in general, to convert measured acceleration signal into displacement signal. One is directly integrating the acceleration signal in time domain. The other is dividing the Fourier transformed acceleration signal by the scale factor of - $\omega$$^2$and taking the inverse Fourier transform of it. It turned out both the methods produced a significant amount of errors depending on the sampling resolution in time and frequency domain when digitizing the acceleration signals. A simple and effective way to convert the time history of acceleration signal into the time history of displacement signal without significant errors is studied here with the analysis on the errors involved in the conversion process.