Dongwook Kim

Abstract The triboelectric nanogenerator (TENG) is a new type of energy generator first demonstrated in 2012. TENGs have shown potential as power sources for electronic devices and as sensors for detecting mechanical and chemical stimuli. To date, studies on TENGs have focused primarily on optimizing the systems and circuit designs or exploring possible applications. Even though triboelectricity is highly related to the material properties, studies on materials and material designs have been rel

Stretchable electronics has emerged over the past decade and is now expected to bring form factor-free innovation in the next-generation electronic devices. Stretchable devices have evolved with the synthesis of new soft materials and new device architectures that require significant deformability while maintaining the high device performance of the conventional rigid devices. As the mismatch in the mechanical stiffness between materials, layers, and device units is the major challenge for stret

Display form factors such as size and shape have been conventionally determined in consideration of usability and portability. The recent trends requiring wearability and convergence of various smart devices demand innovations in display form factors to realize deformability and large screens. Expandable displays that are foldable, multi-foldable, slidable, or rollable have been commercialized or on the edge of product launches. Beyond such two-dimensional (2D) expansion of displays, efforts hav

It is familiar to everyone that human skin and hair easily lose electrons and cause static electricity as they undergo friction with other materials. Such natural regenerative substances take a high ranking in the triboelectric series. Even though the static electricity of regenerative natural substances has been a long-term curiosity in human history, it is not yet clear which of their components causes the positive static charges. This study reveals that lipid layers on the surface of regenera

Transparent flexible transistor array requests large-area fabrication, high integration, high manufacturing throughput, inexpensive process, uniformity in transistor performance, and reproducibility. This study suggests a facile and reliable approach to meet the requirements. We use the Al-coated polymer nanofiber patterns obtained by electrohydrodynamic (EHD) printing as a photomask. We use the lithography and deposition to produce highly aligned nanolines (NLs) of metals, insulators, and semic

Despite the development of various medical imaging contrast agents, integrating contrast signal generation with therapeutic and microrobotic functions remains challenging without complicated fabrication processes. In this study, upconversion nanoparticle-covalent organic framework (UCNP-COF) core-shell sub-micron particles are developed that function as therapeutic microrobots trackable with multi-spectral optoacoustic tomography (MSOT) imaging and can be loaded with desired therapeutic molecula

With emerging interest in foldable and stretchable displays, the need to develop transparent deformable electrode and interconnection is increasing. Even though metal films have been standard electrodes in conventional electronic devices due to their high conductivity and well-established process, they have never been used for transparent deformable electrodes. We present highly conductive transparent deformable Au film electrodes and use them to fabricate a foldable perovskite light-emitting di

Memory to logic system architecture using through silicon stacking (TSS) becomes one of the most promising candidates for the first commercial 3D device due to the continuous demands for small form factor, lower power consumption and higher data bandwidth of mobile devices. Main challenges to bring 3D TSS technology to the volume production level are establishing a cost effective supply chain and building a reliable manufacturing processes. This paper will report recent progress of wide IO memor

Metal halide perovskite nanocrystals (PeNCs) with a controlled quantum size effect have received intense interest for potential applications in optoelectronics and photonics. Here, we present a simple and innovative strategy to precisely tune the photoluminescence color of PeNCs by simply printing perovskite precursor solutions on cellulose papers. Depending on the volume of the printed precursor solutions, the PeNCs are autonomously grown into three discrete sizes, and their relative size popul

Since 2001, LG Cable has been developing the HTS cable system as a member of national DAPAS project. In 2003, 30 m long cold dielectric HTS cable with 22.9 kV, 1260 A/sub rms/ with single core was fabricated to validate the design concept and long-term performance for 4 months. In this year, 30 m long cable with 3 cores in 1 cryostat has been fabricated and installed to conduct long-term reliability test. At this time, the evaluation of basic properties has been completed and long-term test is i

Abstract Research on molecular crystals exhibiting light‐driven actuation has made remarkable progress through the development of various molecules and the identification of driving mechanisms. However, crystals developed to date have been driven mainly by ultraviolet (UV) or blue light irradiation, and driving by red or near‐infrared (NIR) light has not been attempted yet. Herein, a broad‐wavelength light‐driven molecular crystals that exhibit high‐speed bending by photothermal effect is develo

When we display the olfactory information in VR, the controlled release of aroma to stimulate olfactory organ is an important factor. In fact, temporal and spatial control of aroma constituent is the elemental technology. The long-term preservation of the aromatic materials and the miniaturization of olfactory display are also desirable. Most traditional researches on olfactory displays focused on temporal control of aroma, but the importance of spatial control of aroma was not well realized. In

Stretchable electronics have been spotlighted as promising next-generation electronics. In order to drive a specific unit device in an integrated stretchable device, the interconnection of the device should be placed in a desired position and addressed individually. In addition, practical stretchable interconnection requires reliable stretchability, high conductivity, optical transparency, high resolution, and fast and large-scale production. This study proposes an approach to meet these require

Heat transfer and bubble phenomena were investigated by adopting the drift flux model in a viscous slurry bubble column reactor (SBCR), having a diameter of 0.0508 m(ID) and height 1.5 m. The effects of superficial gas velocity (0.002 -0.164 m/s), solid concentration (0 - 20 wt%) and liquid viscosity (paraffin oil; 16.9 mPa•s and squalane; 25.9 mPa•s) on the gas holdup and heat transfer characteristics were examined. It was observed that the gas holdup increased with increasing superficial gas v