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A composite B-pillar was designed and manufactured by design optimization combined with an impact analysis. A carbon-fiber-reinforced plastic (CFRP) was used for the reinforcement part of the B-pillar assembly to substitute the conventional steel materials for reducing the weight of vehicle. To maximize the impact performance by finite element method, the equivalent static loads method was used. The shape, stacking sequence, and thickness of the CFRP reinforcement were optimized to minimize the deflection profile for improving the crashworthiness while reducing the weight. The designed CFRP B-pillar was manufactured and its performance was evaluated by a drop weight test. As a result, the CFRP B-pillar exhibited an improved impact performance and reduced weight compared to those of the conventional steel B-pillar.

Refractive index and thickness of an epoxy molding compound (EMC) were successfully measured without any advance knowledge of properties of material using the Terahertz-Time of Flight System (THz-TFS). The theoretical analysis for calculation of the refractive index and thickness of EMC was conducted considering two time-delay values of emission and detection mode (normal reflection mode and transmission mode). By combining two time-delay values from the normal reflection and transmission modes, the refractive index of EMC could be directly deduced without any parameter of the properties of specimen. The thickness of EMC mold could be simultaneously calculated by using only THz time-delay values. The thickness measurement results using THz-TFS were verified with the thickness measured through scanning electron microscopy (SEM).

In this study, a combined forming-structural analysis of composite structures was performed. Fiber orientation and shear angle changes of the composite materials during its thermo-compression molding processes were predicted with commercial software PAM-FORM. In addition, the material properties, such as elastic modulus and strength, from the shearing of woven fabrics, were measured. The predicted shear angle changes were transformed and reflected to the structural analysis by a self-developed vector-mapping program. The load-displacement curves of the composite structures from the combined forming and structural simulation were compared with the experimental compression and bending test results of hemispherical and U-shaped components, respectively. Finally, it was found that the mechanical behaviors of composite structures can be accurately predicted by the developed combined thermo-forming structural analysis method.

In this work, ultra-high speed flash white light (FWL) sintering method of copper nanoparticle pastes on silicon wafer substrate, was developed to produce highly conductive and low-cost copper electrodes for crystalline silicon solar cells. FWL sintering of copper nanoparticles on silicon wafer substrate has been regarded to be very difficult, due to its high thermal conductivity (k) compared with that of polymer (PI and PET) substrates. To overcome this limitation, we applied multiple pulsed FWL to sinter copper nanoparticles (Cu NPs) printed on silicon wafer. Furthermore, bimodal Cu NPs with different size were also applied to enhance the packing density of Cu films for highly conductive Cu electrodes. Finally, this work demonstrated that Cu NP-pastes are successfully sintered on crystalline silicon wafer substrate by multiple pulsed FWL irradiations.

In this study, design optimization of a composite hood for automobiles was carried out to mitigate the impact of pedestrian head injuries based on finite element analysis. Reduced vehicle, headform impactor and single hood models were established to obtain optimal composite hood designs. The carbon fiber reinforced composite (CFRP) and the hybrid Glass fiber reinforced composite (CFRP/GFRP) laminates were selected as composite material candidates. Both stacking angle sequence and topometry of the composite hood were optimized based on the equivalent static load method. After the optimization, the head injury criterion (HIC), deflection and weight were measured to evaluate the performance of the composite hood. The developed CFRP and hybrid CFRP/GFRP type hoods with optimized final design exhibited the improved impact performance and significant weight reduction while satisfying bending and torsion deflection requirements compared to those of conventional steel and aluminum hoods.

The refractive index and thickness of EMC were measured non-destructively using the terahertz time-domain spectroscopy (THz-TDS) system. A theoretical model was developed using an analysis of time response on transmission and reflection THz signals. Using this developed theoretical model, the refractive index of EMC was measured within 1% of the error range. Simultaneously, the thickness of EMC was calculated through the measured refractive index and induced time delay. As a result, the refractive index and thickness of EMC was measured within the error range of 0.9% and 3.0%, respectively.

Here we report a photonic annealing process for yttria-stabilized zirconia films, which are one of the most well-known solid-state electrolytes for solid oxide fuel cells (SOFCs). Precursor films were coated using a wet-chemical method with a simple metal-organic precursor solution and directly annealed at standard pressure and temperature by two cycles of xenon flash lamp irradiation. The residual organics were almost completely decomposed in the first pre-annealing step, and the fluorite crystalline phases and good ionic conductivity were developed during the second annealing step. These films showed properties comparable to those of thermally annealed films. This process is much faster than conventional annealing processes (e.g. halogen furnaces); a few seconds compared to tens of hours, respectively. The significance of this work includes the treatment of solid-state electrolyte oxides for SOFCs and the demonstration of the feasibility of other oxide components for solid-state energy devices.