A5087881011- Metamaterials and Metasurfaces Applications
- Advanced Antenna and Metasurface Technologies
- Photonic Crystals and Applications
- Thermal Radiation and Cooling Technologies
- Antenna Design and Analysis
- Conducting polymers and applications
- Organic Electronics and Photovoltaics
- Urban Heat Island Mitigation
- Optical properties and cooling technologies in crystalline materials
- Perovskite Materials and Applications
- Injection Molding Process and Properties
- Additive Manufacturing and 3D Printing Technologies
- Atmospheric aerosols and clouds
- Plasmonic and Surface Plasmon Research
- Advanced Materials and Mechanics
- Microwave Engineering and Waveguides
- Ocular Surface and Contact Lens
- Advanced machining processes and optimization
- Cellular and Composite Structures
- Neural Networks and Reservoir Computing
- Fluid Dynamics Simulations and Interactions
- Millimeter-Wave Propagation and Modeling
- Radio Wave Propagation Studies
- Metal and Thin Film Mechanics
- Semiconductor materials and interfaces
Pohang University of Science and Technology
2018-2024
Abstract Deep learning has become the dominant approach in artificial intelligence to solve complex data-driven problems. Originally applied almost exclusively computer-science areas such as image analysis and nature language processing, deep rapidly entered a wide variety of scientific fields including physics, chemistry material science. Very recently, neural networks have been introduced field nanophotonics powerful way obtaining nonlinear mapping between topology composition arbitrary...
Passive daytime radiative cooling (PDRC) devices have enabled subambient of terrestrial objects without any energy input, offering great potential to future clean technology. Among various PDRC structures, random dielectric particles in a polymer matrix or paint-like coatings displayed powerful performances with excellent scalability and easy fabrication. While modeling analyzing such system is nontrivial enhance the effect engineer structures be utilized applications, it essential...
Abstract Sub-wavelength diffractive optics, commonly known as meta-optics, present a complex numerical simulation challenge, due to their multi-scale nature. The behavior of constituent sub-wavelength scatterers, or meta-atoms, needs be modeled by full-wave electromagnetic simulations, whereas the whole meta-optical system can using ray/ Fourier optics. Most techniques for large-scale meta-optics rely on local phase approximation (LPA), where coupling between dissimilar meta-atoms is...
Abstract A crucial aspect in shielding a variety of advanced electronic devices from electromagnetic detection involves controlling the flow waves, akin to invisibility cloaks. Decades ago, exploration transformation optics heralded dawn modern cloaks, which has stimulated immense interest across various physical scenarios. However, most prior research is simplified low‐dimensional and stationary hidden objects, limiting their practical applicability dynamically changing world. This study...
Radiative cooling (RC) has garnered growing interest because of increasing energy demand for cooling, which is partially associated with global warming. While various strategies to improve the performance RC have been reviewed, there limited reviews on functional RC, whose functionalities render traditional radiative coolers aesthetically appealing, transparent, and adaptive. In this review, we briefly introduce fundamental concepts governing overall process RC. We then outline a wide range...
This article presents design methods for a transmissive metasurface antenna composed of four layers meta-structures based on the deep neural network (DNN). Owing to structural complexity as well side effects such couplings among adjacent meta-structures, conventional unit cell strongly relies researcher’s intuition time-consuming iterative simulations. A method with size quarter wavelength operating at frequency 5.8GHz is presented. We describe two unique implementations designing target...
Abstract Intensive development of nanofabrication processes has opened a new window to control electromagnetic waves using subwavelength nanostructures array, named metasurfaces. Although the metasurfaces have succeeded in achieving unprecedented functionality by arranging various shapes modulate properties incident light, inherent passive characteristics make it impossible alter engraved functions after is fabricated. To give tunability metasurfaces, methods been proposed thermal, chemical,...
Abstract Chiral mechanical metamaterials with engineered asymmetric structures have garnered significant interest owing to their potential for manipulating waves and unconventional properties. Although several design methodologies made strides in the discovery of chiral metamaterials, 3D designs that incorporate multiple characteristics remain largely unexplored static dynamic properties these not received sufficient attention. Here, an innovative approach is introduced inverse desired...
The instrumented indentation technique has been investigated to efficiently evaluate the mechanical responses of materials with few limitations on shape and size specimen. There have attempts discover a direct correlation between stress-strain curve indenting load-displacement by introducing concept representative strain stress. However, it is still difficult find relible parameters distinguish similar curves that correspond different limited number experimental datasets. present study...
Physically Transient Electronic Devices (PiTEDs) are building blocks of biodissolvable diagnostics and therapeutics. We fabricate a PiTED integrated with data storage brain-inspired computing capable collection decision-making in case an emergency. It is also compatible the physiological environment human body biologically soluble degradable after performing required task. A flexible transparent biomemristor Mg/collagen/ITO structure fabricated using facile solution-assisted process. The...
Abstract Daytime radiative cooling (DRC) has emerged as a promising method for temperature reduction of surfaces exposed to sunlight, without energy consumption. Despite advancements in DRC design, existing reflector‐based methodologies often lack transparency because visible reflection, hindering the widespread application this technology using glass. Efforts address challenge have led development transparent (TRC), although efficient during daylight remains challenging dominant solar...
We studied the charge-generation mechanism in low-bandgap polymer (P4TNTz-2F)-fullerene bulk heterojunction (BHJ) organic solar cells (OSCs) using transient absorption (TA) spectroscopy. The highly crystalline nanowire structure of P4TNTz-2F a blend film prepared with chlorobenzene (CB) and 1,8-diiodooctane (DIO) induced more long-lived charge carriers than those CB only. Pump-wavelength-dependent TA data revealed that increased charge-delocalization by intrachain ordering CB/DIO is key...
We investigated the side-group and backbone-extension effects of a push–pull conjugated polymer (CP) on charge-generation mechanism in ternary-blend organic solar cells (OSCs) containing PC71BM nonfullerene acceptor (NFA, ITIC). Transient absorption spectroscopy results revealed that CP extension increased hole-transfer efficiency from ITIC to CPs, inducing formation triplet (T1) excitons by nongeminate recombination (via charge-transfer states, 3CT) because finely mixed morphologies....
We investigated the chain-length and fluorination effects on photophysics within push–pull conjugated polymer (CP, Mw 40k/100k PBDB-T 100k PM6) aggregates using transient absorption spectroscopy. Our findings reveal that J-type excitons were more induced in relatively ordered domains than disordered of PBDB-T. Interestingly, induce interchain packing with localized chain cross-linked points, referred to as quasi-interchain packing, due folding increased intrachain rigidity. Two observed PM6...
Rheological properties of bimodal feedstocks containing nano- and micro-particles were studied. To examine nanoparticle effects, five prepared with the contents from 0 to 75 vol. %. Each feedstock was formulated optimal amounts powders, determined critical solids loadings powders. Viscosity measurement performed using a capillary rheometer. From result, flow behavior index activation energy obtained as representative rheological parameters. The moldability for each also calculated compared....
We elucidated chain-extension effects of a benzodithiophene (BDT) and thienopyrroledione-based push–pull conjugated polymer (CP) on its exciton-dissociation mechanism within aggregate systems using transient absoption spectroscopy. The side-group extension CP with benzothiophene the BDT unit induced H-type excitons excess energy owing to decreased chain stiffness. This led interchain polaron-pair (PP)-mediated exciton dissociation. stiff extended thienothiophene also excitons, but breadth...
Sub-wavelength diffractive optics meta-optics present a multi-scale optical system, where the behavior of constituent sub-wavelength scatterers, or meta-atoms, need to be modelled by full-wave electromagnetic simulations, whereas whole meta-optical system can using ray/ wave optics. Current simulation techniques for large-scale rely on local phase approximation (LPA), coupling between dissimilar meta-atoms are completely neglected. Here we introduce physics-informed neural network, which...
The thermal debinding process is one of the most crucial steps in powder injection molding because it consumes a great deal processing time and may introduce defects into component. To enhance production efficiency increase defect avoidance, conditions including maximum temperature, heating rate, holding should be determined based on analysis decomposition behavior. behavior lead magnesium niobate-lead zirconate titanate (PMN-PZT) ceramic feedstock with varying binder compositions was...
Here, we propose a transparent cooler that incorporates top PDMS emitter and bottom semi-transparent reflector. The reflector comprises Bragg mirror perforated metallic film with thickness of 90 microns, reflecting near-infrared Band A visible, respectively. By adding visible reflection via the area film, transparency, reinforced are ensured. Our proposed exhibits significantly improved cooling performance while maintaining visibility.