An optimal design was developed for housing of a 50-ton hydraulic breaker. A four-factor, two-level design was created using the full factorial design, and it was confirmed that the safety factor, the response value, exhibited a curvature. As the curvature was confirmed, a higher-order experiment, a response surface analysis was performed. Based on the Minitab"s optimized prediction of the safety factor and weight, the actual analysis was performed using ANSYS Workbench, the finite element analysis program. As a result, the safety factor was 2.03 and the weight was 3222.2 kg, which was almost consistent with the Minitab’s prediction. The safety factor decreased from 2.33 to 2.03 compared to that in the initial model, but the optimization model can also be judged as being safe because the safety factor was set to 2.00. The weight was reduced by 119.1 kg, from 3341.3 to 3222.2 kg.

Laparoscopic surgical instruments have been used widely since 1980s and they are still important tool to the medical field as the surgical robot systems spread. In this study we devised three types of motorized mechanism to reduce the user hand fatigue. We detailed the mechanism of each type and compared the performances with several indices such as a bending angle, response time and number of mechanical components. And also we show the movement relationships among the jaw joint, passive gimbal set and motors in the case of MPDG (Motor Drive with a Push Disk and Driven Disk of Gimbal Mechanism) type during the typical jaw joint motions. MTPS (Modified Two Parallel Semicircle Guide Mechanism) type excels others in response time and number of components while showing the increase of load and kinematic occlusion during the diagonal movement. MBDG (Motor Drive with a Ball-Screw, Link and Disk Type Gimbal Mechanism) type shows the medium level bending performance with slow response time and large number of components. Lastly MPDG type excels in jaw joint bending performance with an unstable rotation motion transfer between pushing disk and driven disk at the large disk rotation angle.

Automatic tool changers(ATCs) store tools used in a machining center to its magazine and changes the tools automatically. Tools of machine centers are changed and then precisely equipped to spindle system by the ATC. Therefore, the stability and reliability of the ATC is very important. But, there is lack of development and evaluation on basic performance and vibration of the ATCs. So, in this study, a BT40 ATC test bench was developed to verify stability and reliability of BT40 ATCs.

Recently, a high speed spindle is an essential part of machine tools to satisfy latest demand of high precision product and machining of hard materials. But, there are many disadvantages such as heat generation of built-in-motor, bearing friction, noise, vibration and displacement because of the high speed. Many researches on spindle systems have been conducted for solving these problems. In this study, technical trend of machine tools spindle systems are analyzed with patent PSM, mapping and grouping. The analysis is carried out for the applied patent during January 2000 and December 2009 in Korea, Japan, EU and U.S.A. And development of the direction, strategy and promising technologies of the spindle system are suggested.