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Local crustal structures of southern Korea from joint analysis of waveforms and travel times
Wonsup Lee,Chang-Eob Baag 한국지질과학협의회 2008 Geosciences Journal Vol.12 No.4
A joint inversion technique of waveforms and travel times is applied to broadband seismic data from a local earthquake in order to estimate local crustal velocity structures of southern Korea. Combining the waveform and travel time inversion techniques, we can surmount the demerits of the techniques: the distortion of deep velocity structure in the waveform inversion caused by low signal-to-noise ratio (SNR), the velocity-depth trade-off, and errors in picking phases in the travel time inversion. The purpose of this study is not only for verifying whether the technique is performed well in the local areas where the number of stations is limited, but also for estimating the velocity structures of the areas that have been little investigated. We adopted the genetic algorithm (GA) as a search algorithm, since we could not expect appropriate initial models due to little a priori information about crustal velocity structure. Both broadband waveforms bandpassed between 0.05 Hz and 0.3 Hz and travel times of Pg, Pn, and PmP waves from the 26 April 2004 Daegu earthquake (ML=3.9) were used as input data. We performed the joint inversion ten times or more for each local area, and adopted the averaged model of optimal models to acquire credible crustal structure. Synthetic waveforms and travel time curves obtained from the estimated velocity models were generally agreed with observed seismograms, and the estimated source depths from the velocity models of the three local areas are similar to and consistent with each other. Therefore, we believe that the joint inversion technique is still applicable to local areas where the number of stations is limited
Wonsup Lee,Kihyo Jung,Hyunju Lee,Hwagyu Song,Jangkeun Oh,Heecheon You 대한인간공학회 2011 大韓人間工學會誌 Vol.30 No.2
Objective: The present study developed a comprehensive usability testing and analysis framework based on a physical interface model of product and user and applied the proposed framework to usability testing of canister-type vacuum cleaner. Background: The development of a user-centered product design is important to satisfy customers who want to use the product with ease of use and to keep the manufacturer competitive in the market. Method: The proposed testing and analysis framework consists of (1) characterization of physical product-user interface, (2) preparation and administration of usability testing questionnaire, and (3) analysis and interpretation of usability testing results. A usability evaluation of five vacuum cleaners was planned and administered based on the proposed framework and its analysis produced detailed and overall usability testing results for various aspects such as tasks, usability criteria, and design components. Results: The testing results were further utilized to identify usability problems and preferred design features of the vacuum cleaners. Conclusion: The proposed usability testing and analysis framework was found effective to identify preferred features and problems of a product design in a systematic, holistic manner. Application: The proposed framework can be of effective use for practitioners of product design and development to obtain comprehensive, quantitative usability testing information in a systematic manner.