https://scholarworks.unist.ac.kr/handle/201301/19 2026-04-17T06:46:08Z https://scholarworks.unist.ac.kr/handle/201301/91354 Title: Carbon neutrality timing controls future tropical cyclone intensity and precipitation over the western North Pacific Author(s): Lee, Minkyu; Min, Seung-Ki; Cha, Dong-Hyun Abstract: This study examines how different global warming levels associated with near-future carbon neutrality timings influence future tropical cyclone activity over the western North Pacific, using a pseudo-global warming framework. Convection-permitting simulations of multiple landfalling tropical cyclones were performed with the Weather Research and Forecasting model under two Shared Socioeconomic Pathways: SSP1-1.9 and SSP1-2.6, corresponding to net-zero emissions in the 2050 s and 2070 s, respectively. Delayed attainment of net-zero emissions leads to more substantial intensification, with the area affected by strong winds expanding by 7% and 9%, and regions of heavy precipitation by 15% and 22%, under SSP1-1.9 and SSP1-2.6, respectively. These differential responses are driven primarily by thermodynamic changes (atmospheric moisture increase) and also contributed by dynamic changes (enhanced vertical motion). The results underscore that the timing of carbon neutrality is a critical determinant of the severity of landfalling tropical cyclone impacts. 2026-01-31T15:00:00Z https://scholarworks.unist.ac.kr/handle/201301/91337 Title: Pull-out mechanism of striated steel fibers in ultra-high performance concrete (UHPC): Experimental study and analytical modeling Author(s): Pyo, Sukhoon; Tang, Zhengye; Han, Min-Chun; El-Tawil, Sherif Abstract: This study presents the first mechanistic investigation of striated steel fibers, a newly developed fiber type optimized for ultra-high performance concrete (UHPC). Through single-fiber pull-out experiments and finite element (FE) simulations, the research examines the interfacial mechanisms governing load transfer between striated fibers and UHPC. The striated fibers, featuring micrometer-scale surface depressions, exhibit a distinctive multistage pull-out response marked by alternating load rises and drops, which correspond to successive engagement and release of the striations. This behavior, not observed in conventional deformed or smooth fibers, reflects a unique combination of adhesion, frictional sliding, and mechanical interlocking within the dense UHPC matrix. On average, the striated fibers achieved 104% higher maximum pull-out load and 126% greater equivalent bond strength than smooth fibers, attributed to the formation of localized shear keys and enhanced frictional resistance. Detailed computational simulation captured the evolution of these anchorage-sliding cycles and clarified the local crushing and reanchoring of the matrix around each striation. An analytical model was also developed to represent both the frictional and anchorage contributions to pull-out resistance. The findings provide the first direct experimental and numerical evidence of the progressive bond mechanisms in striated fibers and establish a mechanistic foundation for optimizing their geometry and application in next-generation UHPC systems. 2026-06-30T15:00:00Z https://scholarworks.unist.ac.kr/handle/201301/91329 Title: High-rate anaerobic treatment of domestic sewage in EGSB reactors using amended granular sludge down to 10°C Author(s): Park, Jihun; Kim, Jinsu; Choi, Hyungmin; Lee, Changsoo Abstract: With growing demand for sustainable wastewater solutions, anaerobic treatment of domestic sewage has drawn increasing attention. However, under mainstream conditions, it faces kinetic and operational limitations due to the dilute organic content and large flow volume of domestic sewage. This study presents the development of electroactive magnetite-embedded granular sludge (MEG) through the in situ self-embedding of conductive submicron magnetite particles into methanogenic granules as a strategy to enhance the performance and stability of anaerobic domestic sewage treatment under low-temperature mainstream conditions (25-10 degrees C, 8-h HRT). Expanded granular sludge bed (EGSB) reactors supplemented with magnetite (EM) achieved superior chemical oxygen demand (COD) removal (77-90% at 250 mg COD/L influent) and operational stability across all temperature conditions, compared to non-supplemented control reactors (EC; 65-76%). Notably, EM reactors sustained 77% COD removal even at 10 degrees C with a short HRT of 8 h, demonstrating the functional robustness of MEG under low-temperature mainstream conditions. Total methane yield in EM reactors also remained comparable to or higher than that in EC reactors (0.30-0.33 vs. 0.28-0.31 L/g COD fed), with approximately half or more present in dissolved form. This performance enhancement is attributable to the improved settleability, structural stability, and electron transfer capability of MEG, facilitating biomass retention and fostering electric syntrophy. Enrichment of exoelectrogenic bacteria and electrotrophic methanogens, alongside elevated expression of extracellular electron transfer-related genes, further supported the development of electric syntrophy. These findings highlight the potential of the MEG-EGSB system as a promising anaerobic alternative for mainstream domestic sewage treatment. 2026-03-31T15:00:00Z https://scholarworks.unist.ac.kr/handle/201301/91300 Title: ENSO phase transition enables prediction of winter North Atlantic Oscillation one year ahead Author(s): Kim, Kiwook; Lee, Myong-In; Scaife, Adam A.; Smith, Doug M. Abstract: The winter North Atlantic Oscillation (NAO) is a dominant mode of climate variability affecting temperature and precipitation across the Northern Hemisphere, yet its prediction at seasonal-to-decadal (S2D) lead times remains challenging. Here, using multi-year hindcasts from a multi-model ensemble initialized on 1 November for 1962-2019, we show that NAO skill one year ahead improves significantly when the El Ni & ntilde;o-Southern Oscillation (ENSO) undergoes a phase transition next year. This improvement is linked to the northward propagation of anomalous atmospheric angular momentum, which dynamically organizes the NAO and is captured in reanalysis and models. During ENSO transition years, prediction skill increases with ensemble size, and when more than 10 members are used, the forecasts display the signal-to-noise paradox. These findings highlight the potential for enhanced one-year NAO predictability when ENSO transitions are present and large ensemble sizes are used in S2D prediction systems, given the skillful prediction of ENSO phase transitions at one-year lead times by multi-model ensembles. 2026-02-28T15:00:00Z