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Lithium-titanate oxide (LTO) batteries are widely adopted in transportation owing to their high safety, long lifespan, and excellent high C-rate capability. However, studies investigating the thermal runaway behavior of LTO cells under railway operating conditions are limited. In particular, the influence of fault scenarios and environmental factors on battery safety and passenger evacuation time warrants further investigation. To address this, a multi-scale multi-domain (MSMD) model was developed, incorporating a 2RC equivalent circuit model (ECM) for electrochemical behavior and a four-equation model for thermal runaway reactions. Simulations were performed using railway driving profiles under ambient temperatures of − 10, 25, and 40 °C, and heat transfer coefficients (HTC) of 10, 30, and 50 W/m²K. A thermal runaway safety index (STR) was introduced to quantitatively assess battery safety across varying fault and environmental conditions. The results indicated that high ambient temperatures and low cooling efficiency significantly elevate the risk and severity of thermal runaway. Notably, scenarios with a 10 W/m²K HTC and a 5 mΩ external short circuit yielded the lowest STR, indicating a critical safety risk. These findings provide valuable insights for designing safer battery systems and ensuring sufficient evacuation time in railway vehicles equipped with LTO batteries.

Lithium-ion batteries are widely used in various industries, particularly in the transportation sectors, owing to their high-power capacity. Despite these advantages, ensuring their safety remains a serious challenge, as thermal runaway and subsequent thermal propagation events pose substantial risks. Various studies have been conducted on the thermal runaway of battery cells. However, research on battery shape and operating conditions is lacking. In this study, the effects of battery shape and operating conditions on the thermal runaway of lithium titanate oxide battery cells are numerically investigated. An equivalent circuit model and NREL’s four-equation model are employed for the electrochemical reactions and thermal runaway. Prismatic cells demonstrated better heat dissipation compared to cylindrical cells, resulting in a delayed onset of thermal runaway but with a higher thermal runaway temperature. Under non-operating conditions, the thermal runaway occurred 40 s later in prismatic cells, with an 83.5 K higher maximum temperature. Conversely, cylindrical cells experienced faster heat accumulation in the core, leading to an earlier onset of thermal runaway by 295 s compared to prismatic cells under operating conditions. Under operating conditions, the onset of thermal runaway was significantly accelerated. Cylindrical cells reached the thermal runaway temperature at 165 s, which is 345 s earlier than under non-operating conditions, with a peak temperature rate of 33.9 K s −1 , up from 17.5 K s −1 . Similarly, prismatic cells reached a peak temperature rate of 33 K s −1 compared to 18.1 K s −1 under non-operating conditions. These findings underscore the critical role of battery shape and operating conditions in determining the thermal runaway characteristics.

PurposeThe purpose of this paper is to examine the management strategy changes of a government-hosted festival from the government’s perspective based on Ansell and Gash’s (2008) definitive criteria of collaborative governance.Design/methodology/approachThis is a longitudinal case study of Hi Seoul Festival (HSF) in South Korea from 2003 to 2013. First, a detailed description of HSF management strategy change over time is presented through an analysis of internal government documents. Then, factors influencing management strategy changes are investigated through interviews with governmental and professional stakeholders.FindingsThe content analysis of the internal government documents reveals that HSF’s management strategy changed between collaborative governance and contracting out multiple times. The follow-up interviews then found that the prehistory experiences in managing festivals, the change of festival goals, and political leverages influenced the management strategy changes.Originality/valueThe government is one of the key stakeholders of festivals, which sometimes hosts and manages its own festivals. However, how a government manages its own festival is rarely studied. This study would add new insights into the studies of government-hosted festivals.

Cavities are characteristic radiological features related to increased mycobacterial burden and poor prognosis in Mycobacterium avium complex pulmonary disease (MAC-PD). However, cavity changes following treatment and their clinical implications remain unknown. We aimed to elucidate whether cavity obliteration or reduction in cavity size or wall thickness correlates with microbiological cure. In total, 136 adult patients with cavitary MAC-PD treated for ≥ 6 months between January 1st, 2009, and December 31st, 2021, in a tertiary referral centre in South Korea were enrolled. The cavity with the largest diameter at treatment initiation was tracked for size and thickness changes. Following median treatment of 20.0 months, 74 (54.4%) patients achieved microbiological cure. Cavity obliteration, achieved in 58 (42.6%) patients at treatment completion, was independently associated with microbiological cure. In patients with persistent cavities, size reduction of ≥ 10% was significantly associated with microbiological cure, whereas thickness reduction was not. Five-year mortality rates in patients with cavity obliteration, persistent but reduced cavity, and persistent cavity without shrinkage were 95.6%, 72.1%, and 65.3%, respectively ( P  < 0.001). In conclusion, cavity obliteration or shrinkage at treatment completion is associated with microbiological cure and reduced mortality in MAC-PD, suggesting that cavity changes could serve as a proxy indicator for treatment response.

ObjectiveWe aimed to elucidate the clinical factors associated with acute exacerbation and disease progression in young patients with chronic obstructive pulmonary disease (COPD).MethodsThis retrospective longitudinal observational study included patients with COPD aged between 20 and 50 years with post-bronchodilator forced expiratory volume in one second (FEV1)/forced vital capacity (FVC)<0.7. Eligible patients were followed up with ≥2 spirometry examinations at 1 year interval after COPD diagnosis. The primary outcome was moderate-to-severe acute exacerbation in young patients with COPD. Secondary outcomes were early initiation of regular inhalation therapy and accelerated annual post-bronchodilator FEV1 decline.ResultsA total of 342 patients were followed up during a median of 64 months. In multivariable analyses, risk factors for moderate-to-severe exacerbation were history of asthma (adjusted HR (aHR)=2.999, 95% CI=[2.074–4.335]), emphysema (aHR=1.951, 95% CI=[1.331–2.960]), blood eosinophil count >300/µL (aHR=1.469, 95% CI=[1.038–2.081]) and low FEV1 (%) (aHR=0.979, 95% CI=[0.970–0.987]). A history of asthma, sputum, blood eosinophil count >300/µL, low FEV1 (%) and low diffusing capacity of the lung for carbon monoxide (DLCO) (%) were identified as clinical factors associated with the early initiation of regular inhalation therapy. The risk factors associated with worsened FEV1 decline were increasing age, female sex, history of pulmonary tuberculosis, sputum, low FEV1 (%) and low DLCO (%).ConclusionsIn young COPD patients, specific high-risk features of acute exacerbation and disease progression need to be identified, including a history of previous respiratory diseases, current respiratory symptoms, blood eosinophil counts, and structural or functional pulmonary impairment.

The study examined the clinical utility and psychometric properties of the Korean Modified Checklist of Autism in Toddlers (K-M-CHAT)-2. A sample of 2300 parents of 16- to 36-month-old children was recruited across South Korea. A phone interview was utilized to follow up with participants who initially screened positive for autism spectrum disorder (ASD). Item response theory was applied to assess the psychometric properties of the K-M-CHAT-2. Parents’ responses were substantially changed after the follow-up, and the final screen-positive rate was 2.3 %. Results indicated that the psychometric properties of items 1, 3, 11, 18 and 22 were not as strong as the other items. The K-M-CHAT-2 is a useful ASD screening test when implemented with a follow-up.