• Title, Summary, Keyword: spectra

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A Study on the Damping Correction Factors for the Korean Standard Design Spectrum (한국 표준설계스펙트럼의 감쇠보정계수에 대한 연구)

  • Heo, Tae Min;Kim, Jung Han;Lee, Jin Ho;Kim, Jae Kwan
    • Journal of the Earthquake Engineering Society of Korea
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    • v.22 no.1
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    • pp.1-14
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    • 2018
  • In this study, we develop and propose damping correction factors for the Korean standard design spectra. The newly proposed Korean standard design spectra has been given only for 5% damping ratio. But in practice, engineers need design spectra for damping values other than 5%. To obtain design spectra for various damping values from the standard spectra, damping correction factors are derived. These factors modify the shape of design spectra in accordance with the damping ratio. Response spectra for various damping values are calculated from the earthquake records that had been used to calculate standard design spectra. They consist of 55 records from 18 earthquakes occurred in overseas intraplate regions and Korea. The regressed spectra for the damping values ranging from 0.5% to 50 % are compared with standard spectra at three regions acceleration, velocity and displacement sensitive regions. The regression analysis of these data rendered formula for damping correction factors. Finally, a single formula for damping correction factors is recommended that is valid for both horizontal and vertical design spectra and that is applicable to the entire range of periods. One thing to note that recommended damping correction factors is valid for the design spectrum of the rock grounds because the design spectra was developed based on the earthquake records of the rock ground.

Response Spectra of 2017 Pohang Earthquake and Comparison with Korean Standard Design Spectra (2017년 포항지진 스펙트럼과 한국표준설계스펙트럼의 비교)

  • Heo, Tae Min;Kim, Jung Han;Lee, Jin Ho;Kim, Jae Kwan
    • Journal of the Earthquake Engineering Society of Korea
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    • v.22 no.3
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    • pp.129-137
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    • 2018
  • On November 15, 2017, Pohang earthquake occurred. Its local magnitude was announced to be $M_L=5.4$ by Korea Meteorological Administration (KMA). Ground motion data recorded at KMA stations were obtained from their data bases. From the data, horizontal and vertical response spectra, and V/H ratio were calculated. The horizontal spectra were defined as GMRotI50 spectra. From the statistical analysis of the GMRotI50 spectra, a mean plus one standard deviation spectrum in lognormal distribution is obtained. Regression analysis is performed on this curve to determine the shape of spectrum including transition periods. Applying the same procedure, the shape and transition periods of vertical spectrum were obtained. These results were compared with theKorean standard design spectra, which were developed from domestic and overseas intra-plate earthquake records, and Gyeongju earthquake response spectra. The response spectra of Pohang earthquake were found to be almost identical with the newly proposed design spectra. Even the V/H ratios showed good agreement. These results confirmed that the method adopted when developing the standard design spectra were valid and the developed design spectra were reliable.

Wind design spectra for generalisation

  • Martinez-Vazquez, P
    • Wind and Structures
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    • v.30 no.2
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    • pp.155-163
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    • 2020
  • Previous research has shown that wind acceleration components produce a signal that can vibrate single-degree of-freedom oscillators, whose dynamic responses enable to configure design spectra for structures subject to wind. These wind design spectra present an alternative method for evaluating the dynamic response of structures and are a suitable tool for running modal analyses. Here, a generalised method for producing wind design spectra is proposed. The method consists of scaling existing spectra to adjust to a wider range of building properties and terrain conditions. The modelling technique is tested on a benchmark building to prove that its results are consistent with experimental evidence reported in the past.

CALCULATION OF TELLURIC ABSORPTION SPECTRA (지구 대기 흡수선 스펙트럼 계산)

  • Jeong, Gwanghui;Han, Inwoo;Lee, Byeong-Cheol
    • Publications of The Korean Astronomical Society
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    • v.29 no.3
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    • pp.35-44
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    • 2014
  • In ground-based astronomical spectroscopic observations, there are many telluric absorption lines that are laid on the spectra of celestial objects. To study the physical properties of the celestial objects with these contaminated spectra, the telluric lines should be removed. A conventional method for removing the telluric lines is using the standard stellar spectrum as telluric line. In this paper, we introduce a technique to calculate synthetic telluric spectra and use them to remove telluric lines from a spectrum of a celestial object. We used Line-by-Line Radiative Transfer Model (LBLRTM) for calculating a synthetic spectrum and selected Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) model as atmospheric model. We apply our method to some spectra obtained by Bohyunsan Observatory Echelle Spectrograph (BOES) to show that the telluric lines are well removed from the observed spectra by our model within an accuracy of 2% which is close to the 1-sigma rms of the original spectra.

Isomer Differentiation Using in silico MS2 Spectra. A Case Study for the CFM-ID Mass Spectrum Predictor

  • Milman, Boris L.;Ostrovidova, Ekaterina V.;Zhurkovich, Inna K.
    • Mass Spectrometry Letters
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    • v.10 no.3
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    • pp.93-101
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    • 2019
  • Algorithms and software for predicting tandem mass spectra have been developed in recent years. In this work, we explore how distinct in silico $MS^2$ spectra are predicted for isomers, i.e. compounds having the same formula and similar molecular structures, to differentiate between them. We used the CFM-ID 2.0/3.0 predictor with regard to (a) test compounds, whose experimental mass spectra had been randomly sampled from the MassBank of North America (MoNA) collection, and to (b) the most widespread isomers of test compounds searched in the PubChem database. In the first validation test, in silico mass spectra constitute a reference library, and library searches are performed for test experimental spectra of "unknowns". The searches led to the true positive rate (TPR) of ($46-48{\pm}10$)%. In the second test, in silico and experimental spectra were interchanged and this resulted in a TPR of ($58{\pm}10$)%. There were no significant differences between results obtained with different metrics of spectral similarity and predictor versions. In a comparison of test compounds vs. their isomers, a statistically significant correlation between mass spectral data and structural features was observed. The TPR values obtained should be regarded as reasonable results for predicting tandem mass spectra of related chemical structures.

Noise Criteria for the Calculation of Response Spectra (응답스펙트럼 계산을 위한 잡음기준)

  • 노명현;최강룡;윤철호
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • pp.238-246
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    • 2003
  • By using simulated ground motions, which is sum of earthquake signals and noise, we measured the distortion of response spectra due to noise. We found that the distortion is more closely related to the signal-to-noise (S/N) ratio of root-mean-square (RMS) measurement than that of conventional peak measurement. Given a S/M ratio, the distortion of absolute acceleration response spectra is independent on the earthquake magnitude, while that of relative displacement response spectra has a strong dependence on the earthquake magnitude. This means that, when we calculate response spectra from time histories, we can efficiently predict the distortion of acceleration response spectra simply by measuring the RMS SJN ratios, or the distortion of displacement response spectra by combining the RMS S/N ratios and the earthquake magnitudes.

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Evaluation of Bulk-Sensitive Structural Characteristics of Oxidized Single-Walled Carbon Nanotubes using Solution Phase Optical Spectra

  • Lee, Geon-Woong;Bang, Dae-Suk;Cho, Dong-Hwan;Kumar, Satish
    • Carbon letters
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    • v.8 no.4
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    • pp.307-312
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    • 2007
  • A method for evaluating bulk sensitive structural characteristics of unpurified, as-purified, and acid treated single walled carbon nanotubes (SWNTs) was described in the present study. The optical spectra of SWNT solutions were well resolved after prolonged sonication and they were correlated to the diameter and the distribution of nanotubes. The acid-treated SWNTs were similar to as-purified SWNTs in terms of catalyst residue, radial breathing mode (RBM) in the Raman spectra, and the first band gap energy of semiconducting tubes in the optical spectra. The solution phase optical spectra were more sensitive to changes in the small diameter and metallic tubes after the acid treatment than were the RBM spectra.

Development and Application of a Software Tool for the Interpretation of Organic Mixtures' Spectra - Hydrogen Deuterium Exchange (STORM-HDX) to Interpret APPI HDX MS Spectra

  • Lee, Sunghyup;Cho, Yunju;Kim, Sunghwan
    • Bulletin of the Korean Chemical Society
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    • v.35 no.3
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    • pp.749-752
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    • 2014
  • New software was developed for the assignment of elemental formulae based on high-resolution mass spectra and subsequent hydrogen/deuterium exchange data. Entire peaks in high-resolution mass spectra were grouped by their Kendrick mass defect values, and the weighted RMS deviations between theoretical and experimental values were used to determine elemental formulae. After this initial assignment, formulae containing deuterium atoms were sorted in order to interpret hydrogen/deuterium exchange spectra. The software was successfully applied to hydrogen/deuterium exchange spectra of resins and aromatic fractions from heavy crude oil.