SFT, which has a high glass fiber content, is one of the effective methods to replace metal and secure weight reduction and price competitiveness. Also, paintless injection molding in which a functional pattern is applied to the mold surface can eliminate the cost of painting. In this study, three types of SFTs were manufactured by adding round glass fibers measuring Φ7 and Φ10 μm and flat glass fiber measuring 27 × 10 μm for the experiment. DOE (Design of Experiment) was conducted to confirm the change in the warpage of the product and the gloss of the micro pattern due to the cross-sectional shape of glass fibers and the major injection conditions. Based on the results, it was identified that the flat SFT had a very small warpage compared to the round SFTs, and the holding pressure was the main factor in the warpage of all three SFTs. The Φ7 μm SFT had the largest gloss value, and the Φ10 μm SFT and the flat SFT had similar average values. All SFTs demonstrated an enormous change in gloss according to the change in mold temperature. The flat SFT had the smallest standard deviation in both warpage and gloss.

This study presents a new balancing method that utilizes the equations of motion associated with the rotor dynamics system. While the conventional balancing method includes calculation of mass unbalance based on so-called as-is and trial-run techniques, the proposed approach computes mass unbalance by only applying the as-is technique and further explains the critical speed and the damping ratio. A simple test rig was employed to validate the efficacy of the proposed method. A non-central rotor system was utilized as the experimental model, the actual value of the rotor system’s mass eccentricity was measured according to ISO 1940/1-1986(E), and with a comparison done using the results obtained by applying the proposed method. The sensitivity of the measurement error was compared with that of the conventional approach which utilizes the influence coefficient method.

The applicability of flexible OLED devices has been expanding to rollable or foldable displays and lighting. At this time, a system to measure the durability of flexible OLEDs needs to be developed to successfully launch flexible OLEDs in future electronic devices. In this paper, we develop a bending lifetime tester to measure the performance of flexible OLEDs by measuring the luminance of the device in real-time during the bending test. A fixed distance between the bent OLEDs and detector during the bending test improves the accuracy of the measured brightness in real time. This bending tester can measure the lifetime of flexible OLEDs with a mean deviation of less than 0.23% over a temperature range of -30 to 80℃. This performance is sufficient to measure the accelerated lifetime test of flexible OLEDs for reliability engineering.