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479 results on '"Hong, Seokchan"'

1. Synchronization Behavior of Newton's Cradle

Author

Lee, Minseok and Hong, Seokchan

Subjects
Physics - Classical Physics
Abstract

A Newton's cradle is a device that demonstrates conservation of momentum using a series of identical colliding pendula. Despite being a famous example that demonstrates the concept of momentum conservation, extensive analysis of the system is rarely reported in literature. Here, we model the system as a collection of identical nonlinear spring pendulums performing viscoelastic collisions, which shows excellent agreement with experiments performed at various conditions. Dependence of its synchronization rate on four key system parameters are studied in detail. Interestingly, the resonance between radial and angular motion was found to modulate the synchronization rate. The proposed theory with full consideration of two dimensional motion and string hysteresis provides an excellent long-term prediction of the synchronized cradle motion.

Published
2024

21. Comparative risk of serious infections and tuberculosis in Korean patients with inflammatory bowel disease treated with non-anti-TNF biologics or anti-TNF-α agents: a nationwide population-based cohort study.

Author

Kim, Min Jee, Kim, Ye-Jee, Jeong, Daehyun, Kim, Seonok, Hong, Seokchan, Park, Sang Hyoung, and Jo, Kyung-Wook

Abstract

Background: The risk of serious infection and active tuberculosis in patients with inflammatory bowel disease (IBD) has not been concurrently evaluated based on the use of anti-tumor necrosis factor (TNF)-α agents versus non-anti-TNF biologics (vedolizumab/ustekinumab) in the Korean population. Objectives: We compared the risk of serious infection and active tuberculosis in Korean patients with IBD treated with non-anti-TNF biologics (vedolizumab/ustekinumab) or anti-TNF-α agents. Design: This study was a population-based cohort analysis of nationwide administrative claims data. Methods: Health Insurance Review and Assessment Service claims data (representing 97% of the South Korean population) from between January 2007 and February 2021 were reviewed, and adults with IBD who initiated vedolizumab/ustekinumab or anti-TNF-α treatment (n = 6123) between 2017 and 2020 were enrolled. Intergroup differences in the risk of serious infection requiring hospitalization/emergency department visits or active tuberculosis during the follow-up period were analyzed. Results: In the patients treated with anti-TNF-α agents or vedolizumab/ustekinumab during a mean follow-up of 1.55 ± 1.05 and 0.84 ± 0.69 years, the incidence rates of serious infection were 9.43/100 and 6.87/100 person-years, respectively. Multivariable analysis showed no significant intergroup difference in the risk of serious infection with vedolizumab/ustekinumab or anti-TNF-α treatment; the adjusted relative risk of vedolizumab/ustekinumab compared with anti-TNF-α agents was 0.81 (95% confidence interval 0.46–1.44, p = 0.478). Among patients treated with anti-TNF-α agents and vedolizumab/ustekinumab, the incidence rates of active tuberculosis were 0.87 and 0.37 per 100 person-years, respectively. The relative risk of vedolizumab/ustekinumab compared with anti-TNF-α agents was 0.31 (95% confidence interval 0.07–1.26, p = 0.101). In a subset analysis comparing vedolizumab and ustekinumab with anti-TNF-α agents, similar results were observed. Conclusion: In Korean patients with IBD, non-anti-TNF biologics (vedolizumab/ustekinumab) tended to be associated with a lower risk of serious infection or active tuberculosis than anti-TNF-α agents. [ABSTRACT FROM AUTHOR]

Published
2024
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25. Incidence of and risk factors for myelodysplastic syndrome in patients with rheumatologic diseases.

Author

Kim, Young-Eun, Ahn, Soo Min, Oh, Ji Seon, Hong, Seokchan, Lee, Chang-Keun, Yoo, Bin, and Kim, Yong-Gil

Subjects
MYELODYSPLASTIC syndromes, RISK assessment, DATA analysis, STATISTICAL significance, RESEARCH funding, HEMOGLOBINS, FISHER exact test, RETROSPECTIVE studies, TERTIARY care, SYSTEMIC lupus erythematosus, BEHCET'S disease, CHI-squared test, DESCRIPTIVE statistics, LONGITUDINAL method, ANALYSIS of variance, STATISTICS, CONFIDENCE intervals, DATA analysis software, RHEUMATISM, DISEASE incidence, GLUCOCORTICOIDS, PROPORTIONAL hazards models, DISEASE risk factors, DISEASE complications
Abstract

Objective We investigated the incidence of and risk factors for myelodysplastic syndrome (MDS) in patients with rheumatologic disease. Methods We conducted a retrospective cohort study of patients who were diagnosed with rheumatologic diseases at a tertiary care hospital between May 2009 and July 2022 and identified the patients who were subsequently diagnosed with MDS. Each patient with MDS was matched with five age- and sex-matched controls chosen from the cohort of patients with each specific rheumatologic disease. Results During a total follow-up of 55 841 person-years (PY), MDS occurred in 64 patients, yielding an incidence rate of 1.15/1000 PY {median age 57.0 years [interquartile range (IQR) 41.0–69.0], median duration to MDS diagnosis 6.5 years (IQR 3.0–9.0)]. In an age-matched analysis, SLE was a significant risk factor for MDS [adjusted hazard ratio 2.61 (CI 1.19, 36.06), P  = 0.01]. Refractory cytopenia with multilineage dysplasia was the most common phenotype of MDS (35.9%), and more than half of the patients had karyotypes with a favourable prognosis (54.7%). Compared with matched controls, RA, SLE and AS patients with MDS had lower levels of haemoglobin at the time of diagnosis of rheumatologic disease. Furthermore, the MDS patients with SLE and Behçet's disease had higher levels of glucocorticoid use in terms of frequency of use and mean dose than control patients. Conclusion SLE is a significant risk factor for MDS among patients with rheumatologic diseases. A lower haemoglobin level at the time of diagnosis of rheumatologic disease was associated with the future development of MDS. [ABSTRACT FROM AUTHOR]

Published
2024
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41. LSO-003 Effects of progesterone-induced blocking factor 1 on the alleviation of lupus nephritis in MRL/lpr mice

Author

Kim, Young Eun, primary, Kim, Do Hoon, additional, Jeong, Mi Ryeong, additional, Lee, Eun-Ju, additional, Ahn, Soo Min, additional, Oh, Ji Seon, additional, Hong, Seokchan, additional, Lee, Chang-Keun, additional, Yoo, Bin, additional, Sung, Chang Ohk, additional, Shim, Hyun Jae, additional, Cho, Yoo Sook, additional, and Kim, Yong-Gil, additional

Published
2023
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47. Period-doubling Instability of Bose-Einstein Condensates Induced in Periodically Translated Optical Lattices

Author

Gemelke, Nathan, Sarajlic, Edina, Bidel, Yannick, Hong, Seokchan, and Chu, Steven

Subjects
Condensed Matter - Other Condensed Matter
Abstract

We observe the formation of momentum distributions indicative of spatial period-doubling of superfluid Bose-Einstein condensates in periodically translated optical lattices. The effect is attributed to dynamic instability of the condensate wavefunction caused by modulation-induced coupling of ground and excited bands.

Published
2005
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