Jeju National University

Lithium-ion batteries are widely used in various applications such as electric vehicles and energy storage systems owing to their high energy density and excellent stability. Accordingly, various studies are actively underway to improve battery life and suppress degradation; however, most have focused on advancing internal materials such as cathodes, anodes, and electrolytes. This approach has limitations, including complex manufacturing processes, increased costs, and difficulty in applying such changes to existing systems in operation. In this study, we propose an external, nonintrusive approach involving the application of an external magnetic field to a battery to overcome these limitations. This method can improve performance through physical stimulation without altering the internal structure of the cell, making it easily applicable to commercial systems. First, we compared the electrochemical characteristics based on the magnetic polarity using a beaker cell. Subsequently, the optimal conditions to a commercial 18,650 lithium-ion battery were applied to analyze and compare the charge/discharge cycle performance with and without application of magnetic field. Additionally, we conducted electrochemical impedance spectroscopy, electrode surface observations, and X-ray photoelectron spectroscopy of the cells after cycling to comprehensively evaluate the effect of the magnetic field on battery degradation. This study demonstrates the feasibility of improving battery life through a simple and practical approach of applying an external magnetic field, and highlights its potential as an alternative technique to enhance the performance of existing battery systems. • External magnetic fields suppress lithium-ion degradation and improve cycle life. • Beaker-cell EIS found an axial ring magnet with the lowest internal resistance. • Ring(S) and Ring(N) configurations were tested on 18,650 cells for 200 cycles. • Compared with Bare, Ring(S) most improved SOH, efficiency, etc. • MHD/Lorentz-force analysis confirmed that Ring(N) best suppresses degradation.

Enteric methane emissions from dairy cattle contribute substantially to agricultural greenhouse gas output. Although feed-based mitigation strategies have shown promise in controlled research environments, their effects under commercial farm conditions remain insufficiently studied. This field-based study evaluated the associations between methane-mitigating concentrate (MM) feed and milk yield, milk composition, and udder health indicators in Holstein cows across three commercial farms in Jeju, South Korea. A total of 400 lactating cows were monitored over 47 months (January 2021–November 2024) as the farms transitioned from conventional concentrate feed to MM feed. Mixed models and stepwise regression analyses were used to assess the independent effects of MM feeding while accounting for farm, parity, and seasonal variation. MM feeding did not significantly affect overall milk yield or milk fat content. However, MM feeding was associated with lower milk protein, solid non-fat (SNF), and milk urea nitrogen (MUN) concentrations, along with a modest increase in somatic cell count (SCC). These associations varied among farms and parities, indicating that the effects of MM feed are influenced by management and physiological factors rather than a single dietary component. Stepwise regression retained MM feeding as a significant explanatory variable for SNF, MUN, and SCC, but not for milk yield or fat content. These findings indicate that MM feed can be implemented under commercial farm conditions without compromising milk yield, while influencing nitrogen-related milk traits and udder health indicators. Further studies incorporating direct methane measurements and mechanistic evaluation of rumen fermentation and nitrogen utilization are needed to determine the environmental implications of MM feeding.

Objectives: This study aimed to analyze the level of job satisfaction and burnout among dental hygienists in Jeju Province and the relationship between them to provide baseline information for the improvement of the work environment and prevention of burnout.Methods: A 60-question online survey was distributed to dental hygienists working in dental institutions in Jeju.A total of 143 responses were obtained.Statistical analyses were performed using IBM SPSS Statistics (version 23), and statistical significance was set at P<0.05.The analysis methods included frequency analysis, descriptive statistics, Student's t-test, one-way ANOVA, nonparametric tests such as the Mann-Whitney U-test and Kruskal-Wallis test, correlation analysis, and multiple regression analysis. Results:The scores for job satisfaction and burnout were 3.260.58and 3.060.40points, respectively, out of Likert 5 points.Job satisfaction was significantly different according to the type of medical institution, intention to change jobs, position, and age.Particularly, participants in their 40s had higher job satisfaction than those in their 30s.Job burnout was significantly higher in the group that intended to change jobs.Job satisfaction and burnout showed a significant negative correlation, whereas turnover intention showed a negative correlation with job satisfaction and a positive correlation with job burnout.Conclusions: The factors influencing job satisfaction among dental hygienists in Jeju were a higher education level and intention to change jobs.In addition, the intention to change jobs influenced job burnout.Future follow-up studies with larger sample sizes are needed.