As interest in the quality of life has recently increased, there is a growing interest and demand for exercise equipment, such as indoor treadmills or cycles, which can be used at home. However, the use of such indoor exercise equipment has caused social problems by generating noise between floors and causing inconvenience to neighbors. In particular, treadmills that generate a lot of vibration during use cause more social problems in an assembly building, such as an apartment. The purpose of this study is to design dampers of various shapes and to develop dampers with high vibration damping effects through vibration analysis. The damper was installed at the lower end of the treadmill to reduce vibration from the product. Three types of dampers were designed by referring to the damper shape of the existing treadmill, and the vibration reduction effect of each damper shape was verified through structural analysis of the magnitude of vibration generated from the bottom surface of each damper.

Steam turbines of thermal power plants are installed in such a way that packing ring surrounds the entire turbine rotors in order to reduce the amount lost due to a leak of steam and to improve performance. However, the conventional packing ring cannot affect positively fluid velocity of the direction of steam, so it does not have the power to reduce vibration of the rotor. In this research, a study was conducted to reduce it by lowering the rotational speed of steam in the rotor. Anti-swirl teeth which changes rotational speed of steam into axial speed of it, designed in front of the conventional packing rings, and their numbers, twist angles. The characteristics of the rotor and the anti-swirl teeth were chosen as design factors to reduce vibration of the rotor. Through the finite element, the improved packing ring designed with the optimal anti-swirl teeth was developed.

Recently, Laser Direct Imaging (LDI) has been used to replace lithography in Flexible Printed Circuit Board (FPCB) manufacturing. However, repeated motion of a linear motor caused residual vibration in the granite on which the workpiece was placed when the motor either accelerated or decelerated. Because the residual vibration made positioning less accurate, there were more defective products and worse productivity. This paper proposes a way to reduce vibration in the granite during the precision stage. First, the frequency domain of the vibrations of a pneumatic vibration isolator is identified. Second, we present the design of the mechanism using a voice coil actuator and a capacitive displacement sensor. Third, we apply a feedback control algorithm based on PID to cancel displacement. Consequently, we are able to propose an optimal way to reduce vibration for the laser direct imaging equipment. The amount of vibration reduction is evaluated in terms of amplitude and settling time.