Jang-Geun Song

Controllable liquid crystal (LC) defects can provide an effective approach to creating tunable optical vortices. We develop a method to create tunable matter vortex arrays in an LC cell, in which +1 and −1 defects are periodically arranged in a square grid lattice. Spontaneous formation of the periodic defect array is achieved using a spontaneous standing pressure wave without using any patterned electrode or patterned alignment layer. The +1 and −1 defects in the array can induce optical vortic

Functional films made of reactive mesogens (RMs) are widely used in display devices such as liquid crystal displays (LCDs) and organic light-emitting diode displays (OLEDs). While functional RM films have been intensively developed for commercial application in the industrial sector, the fundamental studies on it in the academic sector are relatively limited. Here, functionalRMfilms are reviewed in terms of their materials and fabrication processes as well as their applications in display device

Control systems in machinery equipment provide correction signals to motion units in order to reduce or cancel out the mismatches between sensor feedback signals and command or desired values. In this paper, we introduce a simulator for control characteristics of machinery equipment. The purpose of the simulator development is to provide mechanical system designers with the ability to estimate how much dynamic performance can be achieved from their design parameters and selected devices at the d

Abstract Mechanisms that transform simple rotational motion into desired motions are essential for robots and automobiles. Designing such mechanisms without any baseline is challenging because it requires determining both the topology and dimensions of link-joint connections. To address this issue, computationally efficient gradient-based synthesis methods using ground bar or block models have been developed to automatically determine both topology and dimensions. However, existing methods do no

Amorphous indium–gallium–zinc oxide (a-IGZO) thin-film transistors (TFTs) have attracted significant attention as promising driving devices for next-generation organic light-emitting diode (OLED) displays owing to their high electronmobility (>10 cm²/V·s), wide bandgap transparency, and compatibility with low-temperature fabrication processes (~400 °C). Despite these advantages, a-IGZO TFTs suffer from pronounced electrical instabilities when subjected to prolonged electrical, thermal, and optic

To drive next-generation high-resolution and high-refresh-rate displays, transistors with high mobility exceeding 40 cm2/V·s are essential. Although amorphous Indium Gallium Zinc Oxide (a-IGZO) thin-film transistors (TFTs) are key components of next-generation displays, their conventional mobility of approximately 10–20 cm2/V·s limits their application in these advanced displays and presents a fundamental trade-off between mobility and stability. Increasing the Indium content to enhance mobility