Seungbae Park

Bio: Seungbae Park is an academic researcher from Binghamton University. The author has contributed to research in topics: Soldering & Flip chip. The author has an hindex of 24, co-authored 175 publications receiving 3024 citations. Previous affiliations of Seungbae Park include Purdue University & University of California, Los Angeles.

Fracture Criteria for Piezoelectric Ceramics

Abstract: Fracture criteria for piezoelectric materials were investigated. Mode I and mixed mode fracture tests were performed on PZT-4 piezoelectric ceramics to verify the validity of the mechanical strain energy release rate as a fracture criterion. Experimental results indicated that crack extension could be aided or impeded by an electric field, depending on the field direction. Further, the direction of crack extension was studied. A crack closure method, together with finite element analysis, was introduced to calculate the mechanical strain energy release rate. The maximum mechanical strain energy release rate was used to predict fracture loads under combined mechanical and electrical loads. It was found that the mechanical strain energy release rate criterion is superior to other fracture criteria and predicts fracture loads fairly accurately.

Effect of electric field on fracture of piezoelectric ceramics

Abstract: Closed form solutions for all three modes of fracture for an infinite piezoelectric medium containing a center crack subjected to a combined mechanical and electrical loading were obtained. The explicit mechanical and electrical fields near the crack tip were derived, from which the strain energy release rate and the total potential energy release rate were obtained by using the crack closure integral. The suitability in using the stress intensity factor, the total energy release rate, or the mechanical strain energy release rate as the fracture criterion was discussed.

Design, fabrication, and experimental characterization of a flap valve IPMC micropump with a flexibly supported diaphragm

Abstract: This paper presents the design, fabrication and experimental characterization of a flap valve ionic polymer–metal composite (IPMC) micropump, the diaphragm of which is supported by a flexible material. A multilayered IPMC based on a Nafion/layered silicate and Nafion/silica nanocomposites was fabricated and used as an actuator for the micropump. To make best use of a flexible IPMC diaphragm, we introduced a concept of flexible support and implemented the concept by supporting an IPMC actuator with a compliant polydimethylsiloxane (PDMS) structure at its perimeter. We then fabricated an IPMC micropump with the IPMC diaphragm and flap valves made from the PDMS material. Experiments and finite element analyses were performed to justify the concept of flexible support and to characterize the multilayered IPMC diaphragm and the IPMC micropump. A maximum flow rate of 760 μl/min and a maximum backpressure of 1.5 kPa were recorded at an applied voltage of 3 V and a driving frequency of 3 Hz, even though the performance lasted for a few minutes. The proposed micropump is attractive due to its low operational voltage, lack of leakage problems, simple design, and ease of manufacturing.

Introduction to the Finite Element Method

Abstract: This chapter introduces the finite element method (FEM) as a tool for solution of classical electromagnetic problems. Although we discuss the main points in the application of the finite element method to electromagnetic design, including formulation and implementation, those who seek deeper understanding of the finite element method should consult some of the works listed in the bibliography section.

Semiconductor device, and manufacturing method thereof

Abstract: An object is to provide a semiconductor device of which a manufacturing process is not complicated and by which cost can be suppressed, by forming a thin film transistor using an oxide semiconductor film typified by zinc oxide, and a manufacturing method thereof. For the semiconductor device, a gate electrode is formed over a substrate; a gate insulating film is formed covering the gate electrode; an oxide semiconductor film is formed over the gate insulating film; and a first conductive film and a second conductive film are formed over the oxide semiconductor film. The oxide semiconductor film has at least a crystallized region in a channel region.

Conformal piezoelectric energy harvesting and storage from motions of the heart, lung, and diaphragm

Abstract: Here, we report advanced materials and devices that enable high-efficiency mechanical-to-electrical energy conversion from the natural contractile and relaxation motions of the heart, lung, and diaphragm, demonstrated in several different animal models, each of which has organs with sizes that approach human scales. A cointegrated collection of such energy-harvesting elements with rectifiers and microbatteries provides an entire flexible system, capable of viable integration with the beating heart via medical sutures and operation with efficiencies of ∼2%. Additional experiments, computational models, and results in multilayer configurations capture the key behaviors, illuminate essential design aspects, and offer sufficient power outputs for operation of pacemakers, with or without battery assist.

The Diffusion of Solids

Abstract: IN view of the interest attaching to the vaporisation and diffusion of solids, the following observations may be worthy of record.