Kyoungwoo Park

Aerodynamic Characteristics and Static Height Stability of WIG Effect Vehicle with Direct Underside Pressurization

A 3-dimensional numerical investigation of a WIG effect vehicle with DUP (direct underside pressurization) is performed to predict aerodynamic characteristics and the static height stability. DUP can considerably reduce take-off speed and minimize the hump drag while the vehicle accelerates on the water to take off. The DUP of the model vehicle, Aircat, consists of a propeller in the middle of the fuselage and an air chamber under the fuselage. The air accelerated by the propeller comes into the camber through the channel in the middle of fuselage and augments lift by changing its dynamic pressure to static pressure dramatically. However, the air accelerated by a propeller produces excessive drag and reduces static height stability.

Life Prediction of Automotive Vehicle’s Door W/H System Using Finite Element Analysis

A Vehicle’s door wireing harness arrangement structure is provided. In vehicle’s door wiring harness (W/H) system is more toward to arrange a passenger compartment than a hinge and a weatherstrip. This article gives some insight into the dimensioning process, with special focus on large deflection analysis of wiring harness (W/H) in vehicle’s door structures for durability problem. A Finite elements analysis for door wiring harness (W/H) is used for residual stresses and dimensional stability with bending flexible. Durability test data for slim test specimens were compared with the numerical predicted fatigue life for verification. The final lifing of the component combines the effects of these microstructural features with the complex stress state arising from the combined service loading and residual stresses.

An enhanced tunable rotational energy harvester with variable stiffness system for low-frequency vibration

An enhanced tunable rotational energy harvester for low-frequency vibration is proposed. It consists of a rotational vibrating system and a translating proof mass suspended by wire. The active tuning of the resonant frequency is implemented using the serial connection control of spiral springs, which is named here as a variable stiffness system. The concept, design, and implementation for the proposed device are presented. The numerical simulation and the vertical shaker test are performed, respectively, and the results showed that the proposed energy harvester could effectively generate the electricity under the low-frequency vibration and readily change its natural frequency as well.

Stepwise current electrical sintering method for inkjet-printed conductive ink

An innovative electrical current sintering technique is applied to joule-heat conductive ink by increasing current gradually through a stepwise-form. This stepwise electrical sintering technique is devised to overcome thermal damage of printed conductive ink line during electrical sintering due to its high initial resistance. To monitor a stepwise electrical sintering method, in-situ specific resistance was measured. Surface morphology of the sample was observed by field-emission scanning electron microscope. By increasing the current gradually, the conductive line can endure higher current because the specific resistance has dropped gradually during the process. Finally, enhanced final-step current produces lower specific resistance of the conductive line than that obtained from a constant current-supplying electrical sintering method without damaging printed conductive line.