Seoul National University · Materials Science
Professor Hyun-Joong Kim's research lab specializes in advanced functional materials and sustainable composite technologies, with a strong focus on stretchable electronics, eco-friendly biocomposites, and air purification systems. The lab develops innovative stretchable interconnects using liquid-metal-filled elastomeric microchannels for wearable and flexible electronics, while also advancing the use of renewable materials like polylactic acid (PLA) and paper sludge in high-performance, low-environmental-impact composites. Additionally, the lab designs energy-efficient electrostatic precipitators for indoor air quality improvement, applying fundamental principles of particle charging and collection efficiency. The overarching research direction emphasizes sustainability, mechanical performance, and real-world applicability in emerging green technologies.
Figures are computed from collected data and may differ slightly.
We report on the fabrication and characterizations of a multiaxial stretchable interconnect using room-temperature liquid-alloy-filled elastomeric microchannels. Polydimethylsiloxane (PDMS) microchannels coated at the bottom with a gold wetting layer were used as the reservoirs which were subsequently filled by room-temperature liquid alloy using microfluidic injection technique. Using a diamond-shaped geometry to provide biaxial performance, a maximum stretchability of 100% was achieved (ΔR=0.2
As a result of industrialization and environmental pollution, increasing importance is being given to eco-friendly materials and technology. In particular, eco-friendly biocomposites using polylactic acid (PLA) have attracted great interest. In this work, fiber-reinforced composites were investigated in order to enhance the mechanical properties and improve the economic efficiency of PLA. Specifically, composite materials using natural fibers, such as kenaf were actively studied. In the utilizat
A novel positive-polarity electrostatic precipitator (ESP) was developed using an ionization stage (0.4 × 0.4 × 0.14 m(3) ) with 16 carbon fiber ionizers in each channel and a collection stage (0.4 × 0.4 × 0.21 m(3) ) with parallel metallic plates. The single-pass collection efficiency and clean air delivery rate (CADR) were measured by standard tests using KCl particles in 0.25-0.35 μm. Performance was determined using the Deutsch equation and established diffusion and field charging theories a
This paper reports a biaxial stretchable interconnect on an elastomeric substrate. To increase the stretchability of interconnects, a 2-D diamond-shaped geometry of gold on a polydimethylsiloxane substrate was adopted in which the potentially breakable points were covered with room temperature liquid alloy. Finite element model simulations were performed to identify the most vulnerable points subjected to stress concentration and optimize the design process. Simulations also indicated an optimum
Abstract The effect of paper sludge's particle size and extrusion temperature on the physical and mechanical properties of paper sludge–thermoplastic polymer composites was investigated. In the experiment three levels of particle sizes for the paper sludge and four extrusion temperatures were designed to examine the physical and mechanical properties of these composites. The ash contents of the paper sludge were about 73.7, 46.2, and 38.1% with particle sizes of below 0.15, 0.18–0.25, and 0.42–0
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