Yonsei University

About: Yonsei University is a education organization based out in Seoul, South Korea. It is known for research contribution in the topics: Population & Cancer. The organization has 50162 authors who have published 106172 publications receiving 2279044 citations. The organization is also known as: Yonsei.

Bifurcations and chaos in a permanent-magnet synchronous motor

Abstract: This brief studies dynamic characteristics of a permanent-magnet synchronous motor (PMSM). The mathematical model of the PMSM is first derived, which is fit for carrying out the bifurcation and chaos analysis. Then, the steady-state characteristics of the system, when subject to constant input voltage and constant external torque, are formulated. Three cases are discussed and, for each case, conditions are derived under which the dynamic characteristics of the system are either of steady-state type, limit cycles or chaotic, thus by properly adjusting some system parameters, the system can exhibit limit cycles (LCs) or chaotic behaviors at will. Finally, computer simulations are presented to verify the existence of strange attractors in the PMSM.

Zones of tolerance: alternative scales for measuring information systems service quality

Abstract: The expectation norm of Information Systems SERVQUAL has been challenged on both conceptual and empirical grounds, drawing into question the instrument's practical value. To address the criticism that the original IS SERVQUAL's expectation measure is ambiguous, we test a new set of scales that posits that service expectations exist at two levels that IS customers use as a basis to assess IS service quality: (1) desired service: the level of IS service desired, and (2) adequate service: the minimum level of IS service customers are willing to accept. Defining these two levels is a "zone of tolerance" (ZOT) that represents the range of IS service performance a customer would consider satisfactory. In other words, IS customer service expectations are characterized by a range of levels, rather than a single expectation point. This research note adapts the ZOT and the generic operational definition from marketing to the IS field, assessing its psychometric properties. Our findings conclude that the instrument shows validity of a four-dimension IS ZOT SERVQUAL measure for desired, adequate, and perceived service quality levels, identifying 18 commonly applicable question items. This measure addresses past criticism while offering a practical diagnostic tool.

Guidelines for Laboratory Diagnosis of Coronavirus Disease 2019 (COVID-19) in Korea

Abstract: The outbreak of coronavirus disease 2019 (COVID-19), which began in December 2019, is still ongoing in Korea, with >9,000 confirmed cases as of March 25, 2020. COVID-19 is a severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) infection, and real-time reverse transcription-PCR is currently the most reliable diagnostic method for COVID-19 around the world. Korean Society for Laboratory Medicine and the Korea Centers for Disease Prevention and Control propose guidelines for diagnosing COVID-19 in clinical laboratories in Korea. These guidelines are based on other related domestic and international guidelines, as well as expert opinions and include the selection of test subjects, selection of specimens, diagnostic methods, interpretation of test results, and biosafety.