Ultrasonic cutting is used not only for cutting various materials such as metals and non-metals, but also for bone cutting of the human body or for various surgical operations. In recent, ultrasonic cutting technology is being applied for cutting various food products such as cakes, pizza, and cheese. It is shown that ultrasonic vibrations for cutting food products enables high-precision and high-quality cutting, and the quality of the cutting surface is affected by the shape of food products and cutting conditions. However, most of the studies have been on industrial cutting horns that can be used in large-scale grocery factories, but these cutting horns are very different from the shape of knives used in the households. Accordingly, research or technology development for ultrasonic cutting knives that can be used in household has not been studied. Therefore, this study developed a knife that can cut or process food by applying ultrasonic vibration while having a shape similar to the existing knife as possible so that it can be used in general. To develop such a knife, a modal analysis was performed using the finite element method for knife models of various shapes, and a suitable model for a kitchen knife was proposed.

The importance of environmentally-friendly energy production has been growing globally, and studies on energy storage technologies are underway, to supply produced energy to consumers. Flywheel Energy Storage System (FESS) is physical energy storage technology, that stores generated electric energy into kinetic energy in the rotor. To design the FESS with a high-strength steel rotor, that is inexpensive, recyclable and easy to manufacture, mechanical and electrical components such as a rotor, bearings, etc. are required. Among these, safety of rotor and bearings is critical, because the rotor with high rotating speed may cause axis failure or fracture of the rotating body. Proper size of a rotor for required energy storage and radial, axial forces generated by the spinning rotor was calculated, considering gyroscopic forces acting on the rotating body. Based on the calculation, adequately sustainable angular ball bearings were selected. As a result, by conducting structural, modal and critical speed analysis, safety verification is presented pursuant to the American Petroleum Institute (API) publication 684.

We have designed the structural shapes of a spiral blade and the frame to be used in an Archimedes wind-power system with the objective of increasing its mechanical strength. A conical roll-bending forming process was introduced to fabricate a metallic spiral blade, based on an incremental stepwise approach. From this process, the complicated spiral blade was constructed, and it could be applied to the wind-power mill. We proposed a few structural design concepts for improvement of the mechanical strength of the blade and frame. Fixing rods between the blades increased the natural frequency of the blades three-fold, compared to the original model with no rods. Also, the strength of the frame was increased by introducing edge-flanges with a height greater than 20 mm. This study will be helpful to industrial engineers interested in the structural design of a wind-power system in understanding the structural design process.