Studies on hydrogen storage materials are proceeding worldwide to enhance adsorptive capacity with a proper adsorption energy between physisorption and chemisorption. Graphyne is the carbon allotropes having sp- and sp²-hybridized carbon atoms. It has not been synthesized yet, but have taken the center stage for decades owing to its promising electronic properties and applicability. Therefore, we performed geometry optimization using density functional theory calculation to determine the adsorptive behaviors of graphyne with decoration and doping approaches for improving hydrogen storage. Graphyne decorated with alkali metal cations showed highly adsorptive properties owing to the enhanced basicity by cations, whereas doped graphyne showed a lower adsorption energy within the desirable hydrogen storage range (−0.20 eV to −0.70 eV). Therefore, we applied bimodal surface modification using doped/co-doped graphyne in the presence of alkali decoration. We found that both decoration and doping approaches compensated each other, yielding an energy suitable for hydrogen storage (min: −0.24 eV, max: −0.32 eV), which elucidates the promising properties of a hydrogen storage material.

Urban micro-tidal canals frequently suffer from severe hypoxia due to restricted hydrodynamic exchange and untreated discharges. Field monitoring during a 2022 mass fish mortality event at the Dongsam tidal canal revealed that during the ‘tidal window gap’—a hydraulic stagnation period required for passive tidal flushing—bottom-layer dissolved oxygen plummeted to a critical anoxic state (0.44 mg/L). To overcome passive tidal exchange limitations, this study proposes a hybrid water purification framework integrating active ecological interventions: wall-mounted spiral flow aeration for continuous oxygenation and vertical bio-curtains for pollutant interception. Synergizing fluid mechanics with ecological engineering, core design parameters were systematically derived: effective mixing width (W_eff≈2.5h), longitudinal spacing (L_s = 10 × W_eff), optimal root immersion ratio (D_r/h = 0.6), and climate-adaptive planting densities (ρ_p≈12–32 plants/m²). Additionally, a corrosion-resistant FRP guide rail system was incorporated to facilitate autonomous adaptation to tidal fluctuations. The framework was conceptualized through a prototype design for the Dongsam canal and subsequently scaled to 15 international micro-tidal canals across diverse climatic zones. Ultimately, this research presents a comprehensive methodological framework and a flexible engineering toolkit intended to guide future water quality and ecological resilience enhancements in shallow urban waterways worldwide.

Urban micro-tidal canals frequently suffer from severe hypoxia due to restricted hydrodynamic exchange and untreated discharges. Field monitoring during a 2022 mass fish mortality event at the Dongsam tidal canal revealed that during the ‘tidal window gap’—a hydraulic stagnation period required for passive tidal flushing—bottom-layer dissolved oxygen (DO) plummeted to a lethal 0.44 mg/L. To address the limitations of passive tidal exchange, this study proposes a conceptual hybrid water purification framework integrating active ecological interventions: wall-mounted spiral flow aeration for continuous oxygenation and vertical bio-curtains for pollutant interception. By synergizing fluid mechanics with ecological engineering, core design parameters were systematically derived: an effective mixing width ($W_{eff}=2.2 h$), longitudinal spacing ($L_s$ = 13.6$\times W_{eff}$), an optimal root immersion ratio ($D_r/h$ = 0.6), and climate-adaptive planting densities (${\rho }_p\approx$12–32 plants/m²). Additionally, a corrosion-resistant FRP guide rail system was incorporated to facilitate autonomous adaptation to tidal fluctuations. The framework was conceptualized through a prototype design for the Dongsam canal and subsequently scaled to 15 international micro-tidal canals across diverse climatic zones. The optimized bilateral staggered configuration established a continuous 528 m² ecological refuge, ensuring DO levels recover above the critical 3 mg/L threshold. Ultimately, this research presents a comprehensive methodological framework and a flexible engineering toolkit to guide water quality and ecological resilience enhancements in shallow urban waterways worldwide.

Climate change and urbanization have intensified extreme rainfall, exacerbating urban pluvial flooding risks. Conventional pumps require substantial submergence to suppress air-entraining vortices, delaying early-stage drainage. This study evaluated an inclined horizontal submersible pump (IHSP) with an anti-vortex suction cover designed for preemptive drainage at an ultra-low water level (0.5D). A 390-ton full-scale facility simulated an extreme inflow of 21.0 m³ min⁻¹. Compared to conventional activation at 1.9D, preemptive operation extended the time to reach the critical inundation level (1.80 m) from 6 min 52 s to 13 min 17 s, yielding an observed macroscopic delay of 6 min 25 s in the experimental tank. Geometrically scaling this by the tank-to-field area ratio (4.67) yields an idealized theoretical reference of 1 min 22 s, which serves as a conceptual baseline rather than a deterministic field prediction. During continuous low-load standby, motor-current deviations remained tightly constrained (maximum 2.07%), well within the study-specific ±7.5% screening criterion while eliminating chattering-induced electromechanical stress. Furthermore, an 11-year life cycle cost assessment revealed a 33.2% expenditure reduction, primarily from eliminating deep-sump excavations. These findings demonstrate that the IHSP provides stable low-water-level operation and preemptive drainage for enhanced urban flood response.