The demand for flexible electronic materials used in wearable devices has experienced a significant surge in recent years. Wearable devices typically incorporate an electronic material or system that can be mounted on a human body. It is imperative that these materials are composed of substances compatible with the human body. Consequently, numerous studies have been undertaken to develop flexible electronic devices with various performance capabilities. In this study, nanowire patterns were manufactured on nanofibers and utilized as patches. To create a nanowire pattern, a direct-write spraying process was employed to investigate changes in electrical characteristics using process variables. The process involved depositing silver nanowires on the surface of nanofibers using a pneumatic spray nozzle. Generated patterns were found to be suitable for use as sensors capable of withstanding skin-attached deformation.

There are various conduit structures such as arteries, veins, and airways in the human body, and they play critical roles in each tissue/organ. However, in recent years, the demand for artificial substitutes for the damaged conduit structure-based tissues and organs has significantly increased as dietary life has rapidly changed. Accordingly, various studies have been conducted, to develop a conduit structure of biocompatible polymers. In this study a 5 mm-diameter conduit structure was developed, using electrospinning process. An electrospinning setup equipped with a cylindrical-rod collector was constructed to fabricate a fibrous conduit structure, and then the impacts of process conditions on morphological and mechanical properties were investigated. Finally, it was shown that the mechanical properties of the fibrous conduit structure in circumferential direction, can be controlled by the electrospinning process conditions.

The collaboration of robots and humans sharing workspace, can increase productivity and reduce production costs. However, occupational accidents resulting in injuries can increase, by removing the physical safety around the robot, and allowing the human to enter the workspace of the robot. In preventing occupational accidents, studies on recognizing humans, by installing various sensors around the robot and responding to humans, have been proposed. Using the LiDAR (Light Detection and Ranging) sensor, a wider range can be measured simultaneously, which has advantages in that the LiDAR sensor is less impacted by the brightness of light, and so on. This paper proposes a simple and fast method to recognize humans, and estimate the path of humans using a single stationary 360° LiDAR sensor. The moving object is extracted from background using the occupied grid map method, from the data measured by the sensor. From the extracted data, a human recognition model is created using CNN machine learning method, and the hyper-parameters of the model are set, using a grid search method to increase accuracy. The path of recognized human is estimated and tracked by the extended Kalman filter.

Recently, porous structures of nano/microfibers are receiving great attention because of their excellent mechanical properties, surface area to volume ratio, and permeability. In this study, thick microfiber mats were fabricated using a melt-electrospinning process in a controlled manner. A melt-electrospinning equipment including a three-axis precision motion control with pneumatic dispensing was constructed. The diameter and deposition pattern of melt-electrospun microfibers with respect to the barrel temperature and pressure were investigated. Based on identified effects of process conditions on microfiber geometry, thick microfiber mats with various properties were successfully fabricated using melt-electrospinning with snake scanning and iterative layering. Their mechanical properties and porosities were then compared and analyzed.

Recently, carbon fiber-reinforced plastic (CFRP) has been attracting much attention in various industries because of its beneficial properties such as excellent strength, modulus per unit density, and anti-corrosion properties. However, there are several issues in its application to various fields. Severe tool wear issues in its machining have been noted as one of the most serious problems because it induces various serious machining failures such as delamination and splintering. In this regard, timely tool replacement is essential for reducing the influence of tool wear. In this study, tool wear, especially flank wear, in the CFRP drilling was investigated and monitored. First, the reproducibility of tool wear under the same machining condition was experimentally evaluated. And it is demonstrated that tool wear may remarkably differ even though the same machining condition is applied to the tools. Then, tool wear monitoring based on the feed motor torque was applied to the detection of tool life ending in the CFRP drilling process. Consequently, it was demonstrated that the average and maximum detection error of the tool life end were less than 7 and 14%, respectively.

Chip on glass (COG) bonding using anisotropic conductive film (ACF) is a key technology to assemble a driver IC onto a LCD glass panel. In this paper, an experimental investigation was conducted to investigate the correlation between contact resistance and characteristics of image taken by machine vision based inspection system. The results show that the contact resistance was strongly influenced by the contrast ratio of conductive particle rather than the number of conductive particles. Also, number of conductive particles whose contrast ratio is below 0.75 is crucial for determining the quality of the assembled samples. On the other hand, in the result of high temperature high humidity storage test, the contrast ratio of samples was increased. However, in the case of open-circuit samples after temperature humidity storage test, the number of conductive particles whose contrast ratio is above 0.75 was more than that of the closed-circuit samples.

Nanopositioning technologies play an important role in the progress of electronics, optics, bioengineering and various nano-scale technologies. As a result, various practical nanopositioning methods have been successfully introduced. Flexure mechanism is a valuable method in nanopositioning because of smooth and friction-free motion and the infinitesimal movement near to sub-㎚. In this study a modularized nanopositioner based on parallelogram four-bar linkage structure with right-circular flexure hinge was developed. The positioning performance of a single axis nanopositioner and a XY nanopositioner which was extended from single axis one were demonstrated using control experiments. Consequently, it was shown that the developed single axis nanopositioner possessed high performance and could be extended to various multi-axis nanopositioners.

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 designing phase. The simulator has a database for commercial parts, so that the designers can choose appropriate components for servo controllers, motors, motor drives, and guide ways, etc. and then tune governing parameters such as controller gains and friction coefficients. The simulator simulates the closed-loop control system which is built and parameter-tuned by the designer and shows dynamic responses of the control system. The simulator treats the moving table as a 6 degrees-of-freedom rigid body and considers the motion guide blocks stiffness, damping and their locations as well as sensor locations. The simulator has been under development for one and a half years and has a few years to go before the public release. The primary achievements and features will be presented in this paper.

The effect of COG bonding parameters, especially the bonding temperature, on the bonding quality and reliability was investigated in this paper. We measured the bubble area formed in the ACF resin during the bonding process and tried to investigate the relationship between bubble area and bonding peel strength. 85/85 test which exposes a sample to a 85% humidity and 85℃ temperature condition was also carried out. The bubble area was dramatically increased under ~10℃ lower than recommended bonding temperature. The bubble area formed at the edge of IC chip was larger than the other parts of IC chip. But the peel strength was not associated with the bubble area. High temperature and humid condition made the bubble area larger, but we could not find clear trend of change in the peel strength.