In this study, the heat transfer characteristics of one-side heated screw tubes were analyzed using subcooled flow boiling experiments. The experiments were performed until the critical heat flux was reached, while the applied heat flux was gradually increased. Subsequently, the boiling curves derived from the experimental results were divided into partial nucleate boiling (PDB) and fully developed nucleate boiling (FDB) regimes. As the flow rate increases, the forced convective heat transfer is enhanced, improving the single-phase heat transfer performance. However, as the FDB region is approached, most of the heat transfer proceeds via nucleate boiling heat transfer, so the heat transfer coefficient curve converges into the same straight line. The same trend was observed when analyzing the effect of the degree of subcooling. However, as the system pressure increased, and the liquid surface tension and latent heat decreased, a faster transition was observed from the single-phase regime to the PDB regime. From evaluating the prediction performance of the existing subcooled flow boiling heat transfer correlations, among the PDB regime; Liu and Winterton correlation, a kind of Chen-type correlation, showed the highest accuracy with mean absolute error (MAE) of 13.62% and root mean square error (RMSE) of 16.13%. However, most of the FDB correlations did not accurately predict the heat transfer performance of the one-side heated screw tube under a high heat flux load of several MW/m². Therefore, a new screw tube FDB correlation was developed using Python code combined with artificial intelligence technology. The authors believe that the proposed correlation will be useful for not only predicting the heat transfer performance in the FDB region, but also establishing an operating map of the screw tube in the future.

In this study, the onset of flow instability (OFI) of the hypervapotron channel was experimentally explored under one-side high heat load conditions. The OFI was detected based on the heat flux ( q ″ ) where the standard deviation of the inlet pressure rapidly increased. Moreover, the effect of the system parameters was analyzed, showing that the OFI q ″ increased as the inset subcooling and mass flow rate increased. The reason is the high subcooling and flow rate that rapidly condense the vapor, which is the leading cause of OFI. Unfortunately, because most of the OFI correlations in previous studies were developed based on micro-channels, these correlations could not predict the hypervapotron OFI q ″ properly under one-side high heat load conditions. Finally, the authors found that the Reynolds number and Jakob number were inversely proportional to the ratio of the OFI heat flux ( q O F I ″ ) and saturation heat flux ( q s a t ″ ). Furthermore, a new correlation was developed using a PYTHON code and an artificial intelligence technique (mean absolute error rate = 12.89%, root mean square error rate = 14.81%).

Background. Obstructive airway disease is a major health problem and has a great impact on global socioeconomic burden. Despite therapeutic advances in recent decades, there is still a need for effective and safe therapeutic agents for patients with asthma or chronic obstructive pulmonary disease (COPD). Methods. This prospective observational study explored the effects of herbal medicines in patients with asthma and COPD. All participants visited the hospital at least every 4 weeks for 12 weeks to receive their herbal medicines based on their pattern identification and to evaluate safety and efficacy endpoints. We followed the diagnostic criteria used by Korean medicine doctors to prescribe herbal medicines, explored variations in prescribed herbal medicines, and explored a number of clinical features in patients with asthma or COPD. Results. A total of 24 patients were enrolled: 14 were diagnosed with asthma and 10 with COPD and 19 completed the study. After 12 weeks of herbal medicine treatment, herbal medicines significantly improved the modified Clinical Asthma Measurement Scale in Oriental Medicine-V in asthma patients and the modified Medical Research Council Dyspnoea Scale and St. Georges Respiratory Questionnaire in COPD patients. For all patients, modified Medical Research Council Dyspnoea Scale score and interleukin-13 were found to be significantly different after treatment. Additionally, the majority of patients were satisfied with our herbal medicine treatments, and no severe adverse events were reported during the study. Conclusions. Our study provides preliminary clinical data on the safety and efficacy of herbal medicines in patients with asthma and COPD.

Conventional treatments for allergic rhinitis (AR) exhibit insufficiency and long-term use-related side effects. Considering the reported anti-inflammatory and immunoregulatory effects of Bojungikgi-tang (BJIGT), we aimed to assess its efficacy on persistent AR (PAR). Patients with PAR were randomly assigned in a 1:1:1 ratio into high-dose BJIGT, standard-dose BJIGT, and placebo groups, followed by 1-week run-in and 4-week treatment periods. The primary outcome included the mean change in Total Nasal Symptom Score (TNSS), with secondary outcomes encompassing the Korean Allergic Rhinitis-Specific Quality of Life Questionnaire, biomarkers, overall assessment, TNSS by AR pattern identification, and the Sasang constitution. The mean TNSS change was more improved in the BJIGT group than in the placebo group; however, no statistically significant differences were observed. Additional interaction effect analysis revealed a statistically significant improvement in the high-dose BJIGT group compared with the placebo group from weeks 1–2 to weeks 3–4. Regarding secondary outcomes, the BJIGT group exhibited similar or improved results compared with the placebo group, showing no statistically significant differences. No serious adverse effects or clinically significant changes in safety assessments were observed. Given that this study validated clinical improvement and safety, it serves as potential groundwork for pertinent future studies.