Chiyen Kim

A study to detect a material deposition status in fused deposition modeling technology

Fused deposition modeling (FDM) technology, one of the most commonly used by 3D printers, builds parts layer-by-layer by heating and extruding thermoplastic filament. However, building failures such as nozzle clogging, substrate deformation, etc. often occur when using FDM systems. All of these failures are unpredictable and undetectable, resulting in lost time and money. The present research studies a methodology to detect the material deposition status to solve this crux of FDM 3D printing by sensing the inner pressure change of the liquefied material. The paper hypothesized that the change in deposition status of the FDM system affects the current supplied to the feeding motor in the extrusion head due to a chain reaction. This was corroborated by experiments which investigated how supplied current reacts when an unexpected substance invades the deposition area during a build.

Study for the Indirect Measuring Method of Operational Force in Surgical Robot Instrument

This paper proposes the method indirectly measuring the operating force of the end-effect tip of surgical robot instrument which conducts the surgical operation in the body on behalf of the surgeon`s hand. Due to the size and safety obligation to the surgical robot instrument, it is difficult to measure the operation force of its tip like grasping force. However the instrument is driven by cable-pulley torque transmission mechanism and when some force is occurred at the tip, then the reaction force appears on the cable as additional tension. Based on this phenomenon, this paper proposes a method to estimate the operating force from measuring reaction force against the driving motor by using a loadcell. And it induces mathematical equation to calculate the force from loadcell by approaching the modulus of elasticity to high order polynomial. And this paper proves the validity of proposed mechanism by experimental test.

3D Printed Electronics With High Performance, Multi-Layered Electrical Interconnect

2-D printed electronics have been the focus of intense research for the past two decades primarily focused on implementing electrical interconnect by dispensing conductive binder-based inks. More recently, traditional printed electronics processes have been leveraged within 3-D printed structures where components and interconnect are introduced during fabrication interruptions. The dielectric performance of 3-D printed materials compares well with traditional printed circuit board (PCB) dielectrics but one remaining challenge is the low conductivity of printed ink traces. The performance degradation is due to curing temperature limits imposed by the properties of the polymer substrates. Thermoplastics, such as ULTEM, can maintain form at over 200 °C, but production ink curing processes require 850 °C to provide an appropriate conductivity. Previous reports have described submerging wires with selective energy within a thermoplastic substrate upon which 3-D printing can continue uninhibited. As copper wires have the same conductivity as PCBs and can be implemented in a wide range of cross-sectional areas, 3-D printed electronics are now in a position to transform the electronics industry. This paper describes an inter-layer process to insert metal connection between layers—allowing for improved routing density and leveraging the geometries brought to bear by 3-D printing. Minimum placement distance between these 3-D printed vias was initially 1.5 mm, and the vias can connect layers separated by as much as 2.8 mm in the vertical build direction (z-axis). As the number of wires layers that can be fabricated is not as limited as traditional board lamination, complex routing can be realized within mass customized, arbitrary shapes.