This paper proposes a simplified path-following control method for an Unmanned Surface Vessel (USV) considering towed Unmanned Underwater Vehicles (UUV). For dealing with an effective USV dynamic model, 1st order of the linear system with time delay and gain value are applied rather than applying a non-linear dynamic model, and it is identified with real vessel data from several straight and turning experiments. Then, USV attitude and velocity are controlled by multi-loop Proportional-Derivative (PD) and proportional controller. A USV guidance scheme is derived through a UUV guidance scheme to support autonomous navigation for towed UUV, and combination of cross track and Line of Sight (LOS) guidance is presented for adaptive path following. Finally, to validate the performance of the proposed USV path-following control method with respect to the towed UUV guidance scheme, the results of simulations are presented.

Nowadays, Three dimensional printing (3DP) technique that is one of solid freeform fabrication (SFF) technology has been notable issue, and has been applied by various fields. The SFF system can fabricate three dimensional objects of solid freeform with high speed and low cost using ink jet printing technology. In this research, a SFF system to analyze 3DP process technology is developed. We applied sliding mode control with sliding perturbation observer (SMCSPO) algorithm and minimized position error to the developed SFF system. We analyzed and optimized process variables such as jetted volume, layer thickness, powder bed and so on experimentally. Also, the dimensional error of a developed SFF system is evaluated. Finally, the feasibility of application to bio manufacturing is presented through successful fabrication of teeth and cranium model.

Digital 3D Real Object Duplication System (RODS) consists of 3D Scanner and Solid Freeform Fabrication System (SFFS). It is a device to make three-dimensional objects directly from the drawing or the scanning data. In this research, we developed an office type SFFS based on Three Dimensional Printing Process and an industrial SFFS using Dual Laser. An office type SFFS applied sliding mode control with sliding perturbation observer (SMCSPO) algorithm for control of this system. And we measured process variables about droplet diameter measurement and powder bed formation etc. through experiments. In case of industrial type SFFS, in order to develop more elaborate and speedy system for large objects than existing SLS process, this study applies a new Selective Dual-Laser Sintering (SDLS) process and 3-axis Dynamic Focusing Scanner for scanning large area instead of the existing f lens. In this process, the temperature has a great influence on sintering of the polymer. Also the laser parameters are considered like that laser beam power, scan speed, and scan spacing. Now, this study is in progress to evaluate the effect of experimental parameters on the sintering process.