We have developed a direct conductive patterning method with micro-scale line widths using the laser-induced-forward transfer (LIFT) and liquid metal. As this method does not need post-thermal processing, there is no thermal damage even on heat-sensitive polymer substrates by low-power laser irradiation on the dynamic release layer (DRL). Unlike other liquid metal patterning processes, this procedure can easily achieve fine line widths of a few tens of micrometers corresponding to laser spot size. The solid-state UV pulse laser with 266 nm wavelength and 20 ns pulse duration was used to transfer Eutectic Gallium Indium (EGaIn) liquid metal and the results for the single and multi-pulse laser irradiation were investigated to determine the effective process conditions. The applicability of flexible circuit fabrication and selective circuit repair was successfully tested on Polyimide (PI) substrate. After the LIFT process, the electrical properties of liquid metal on the pattern were measured to be approximately 5~8 x 10^-3 Ω/m of resistance.

In this study, design for additive manufacturing (DfAM) of release agent injection manifold for hot forging has been performed to achieve weight reduction and flow path optimization. The weight reduction of 53.5% was achieved, thereby enabling the application of stainless steel 316L, which has high strength and corrosion resistance. Lightweight manifolds using Al-Mg-10Si and SUS316L materials were fabricated by PBF-type metal 3D printer. The feasibility test showed that mold life was improved by 14% by solving residual release agent problem. In addition, the flow path optimization results suggested that the flow standard deviation of each outlet dropped sharply from 264 to 75 ㎤/s. This approach demonstrated that DfAM for release agent manifold could be applied to increase mold life and improve product quality and productivity for hot forging.

The main function of aircraft ejection system is that it separates the store from the aircraft. The ejection force is important for the safety of the aircraft when the store is ejected, because the store can be lifted by air flow affected by the aircraft’s speed. If the ejection force is low, the aircraft can be damaged by the floating store. The ejection force of the suspension system should be designed in order to release the store safely. In this study, the ejection force of the pyrotechnic suspension using the cartridge to eject the store was researched. This research was performed, based on the precedent study about the over-center linkage mechanism and the pressure drop by the orifice. The ejection force was calculated, after analyzing mathematical fundamentals about the pressure in the system of the suspension and analyzed through AutoDyn and ADAMS software. Finally, the theoretical results were compared with the ejection test results of the suspension system.

A programmable drug delivery system can control the release rate of a drug. It can minimize side effects while maximizing therapeutic effects. In this research, we investigated the feasibility of producing a programmable drug delivery system using 3D printing technology. A capsule with a micro-orifice and a drug-laden hydrogel was designed. The designed system was then fabricated by the printing process using polycaprolactone and hydrogel. The printed drug delivery system was immersed in PBS at 37°C and the number of molecules released was measured thorough colorimetric analysis. The effect of diameter and length of the micro-orifice and concentration of the hydrogel on drug release characteristics was then determined. The initial burst release rate was found to be increased with increasing orifice size. Increasing the length of the orifice linearly delayed the start time of drug release. At length of 600 μm and 1,200 μm, drug release was initiated after 36 h and 72 h for, respectively. When the concentration of hydrogel was increased, drug release rate tended to decrease. These results successfully confirmed that a drug delivery system with controlled release rate and initiation time could be manufactured using 3D printing technology.