Publications by authors named "Seungjo Lee"

We present a mold-free high-resolution nanopatterning technology named piezo-actuated one-axis vibrational patterning (POP) that enables continuous and scalable fabrication of micro- and nanopatterns with precisely programmable periods and dimensions. POP utilizes the piezoelectric stack-actuated high-precision uniaxial vibration of a flat, pattern-free rigid tool edge to conduct sub-50 nm-periodic indentations on various compliant substrates laterally fed underneath. By controlling the tool vibration frequency, tool temperature, and substrate feed rate and by combining sequential tool strokes along multiple directions, diverse functional micro- and nanopatterns with variable periods and depths and multidimensional profiles can be continuously created without resorting to mold prefabrication.

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Article Synopsis
  • The study introduces a method called controlled dynamic nanoinscribing (DNI) for creating customized nanopatterns with different shapes, depths, and dimensions on flexible materials without leaving any rough edges.
  • By adjusting key processing factors like inscribing force, temperature, and substrate feed rate, researchers can fine-tune the nanopatterns, allowing for both rounded and angular profiles.
  • The technique also enables the creation of complex patterns with varied depths and designs, which can be applied to various fields such as precision machinery, transparent electronics, and wearable devices, exemplified by the ability to control light diffusion in LEDs using DNI nanopatterns.
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We develop a facile route to the scalable fabrication of flexible reattachable ionomer nanopatterns (RAINs) by continuous nanoinscribing and low-temperature roll imprinting, which are repeatedly attachable to and detachable from arbitrarily shaped surfaces. First, by sequentially performing continuous nanoinscribing over a polymer substrate along the multiple directions, we readily create the multidimensional nanopattern, which otherwise demands complex nanofabrication. After its transfer to an elastomer pad for use as a soft nanoimprinting stamp, we then conduct a low-temperature roll imprinting of the ionomer film to fabricate a flexible and highly transparent RAIN.

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We present a facile and scalable coating method based on controlled airbrushing, which is suitable for conformal resin coating in continuous roll-to-roll (R2R) nanoimprint lithography (NIL) process. By controlling the concentration of UV-curable polymeric resin with mixing the volatile solvent and its airbrushing time, the coated resin film thickness can be readily tuned. After R2R NIL using a flexible nanoscale line pattern (nanograting) mold is conducted upon the airbrushed resin film, a large-area uniform nanograting pattern is fabricated with controlled residual layer thickness (RLT) based on the initial film thickness.

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We develop scalable 3D plasmonic nanoarchitectures comprising a double-bent nanoscale Au strip array integrated within the transparent nanograting framework, which can be continuously fabricated on a large-area flexible substrate via roll-to-roll nanoimprint lithography and angled Au deposition, realizing localized surface plasmon resonance with higher sensitivity in a smaller footprint.

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We report on a measurement of giant second-harmonic Hall voltages which occur without a magnetic field and do not change their sign on current reversal in a two-dimensional electron system with a transverse density gradient. A quadratic dependence on the electric field, a strong temperature dependence, and both magnitude and directional dependence on the magnetic field are also observed. Such behavior points towards a plausible explanation based on a novel spin Hall effect with in-plane spin polarization.

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Using two-wave panel survey data (N = 348) collected in South Korea in the context of H1N1 flu, we explored several important aspects of optimistic bias that have been relatively unexplored in previous research, including: (a) the extent to which risk communication and indirect risk experience affect changes in optimistic bias over time; (b) the utility of the concept of optimistic bias to predict subsequent risk behavior; and (c) how optimistic bias moderates the effect of risk communication and indirect risk experience on self-protection behavior. The findings revealed that optimistic bias is rather enduring and resilient, as it changed only under one condition (high indirect risk experience combined with low interpersonal communication). Optimistic bias had a nonsignificant association with self-protection behavior, but played an important moderating role by reducing the effect of interpersonal communication on self-protection behavior.

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This experiment uses the limited capacity model of mediated message processing (LC3MP) to investigate the effects of production pacing and arousing content in radio public service announcements (PSAs) on the emotional and cognitive responses of college-age and tween (9-12-year-olds) participants. The LC3MP predicts that both arousing content and production pacing should increase emotional arousal, physiological arousal, cognitive effort, and encoding up to the point of cognitive overload after which cognitive effort and encoding should decrease. Results showed that, as expected, arousing content did increase emotional arousal and cognitive effort for both tweens and college students, though the effect was larger for college students.

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