Poly(lactic acid) (PLA) is considered as one of the most promising bio-based polymers due to its high strength, high modulus, good processability, transparency after processing, and commercial availability. This study aimed to investigate the mechanical, thermal, and migration properties of poly(lactic acid)/zeolite (10 phr) composites prepared with various biocompatible plasticizers, such as triethyl citrate(TEC), tributyl citrate(TBC), and poly(ethylene glycol)(PEG400), through differential scanning calorimetry(DSC), thermo-gravimetric analysis(TGA) and standard tensile testing. The incorporation of PEG400 significantly increased the elongation at break, and DSC results showed that the addition of plasticizers drastically decreased the T_g of PLA/zeolite composites and improved the melt flow and processability. Besides, it was found from TGA results that PLA/zeolites composites plasticized by TEC and TBC were more easily to be thermally degraded than the composites plasticized by PEG400.

The characteristics of vibrational stress (shock and vibration) during transport and the possibility of damage to the packaged pears were investigated. And this study was conducted to analyze how environmental conditions during transportation affect quality factors such as oxygen (O₂) and carbon dioxide (CO₂) concentrations, weight loss rate, ethylene production, soluble solids content (SSC), and firmness (bioyield strength) of packaged pears for exporting. Pears with or without vibration stress were stored for 30 days at low temperatures (5 ± 0.8℃, 80 ± 5% relative humidity). Statistically significant difference (p ≤ 0.05) between pears with and without vibrational stress for oxygen concentration (O₂; 11.8 ± 1.5% and 16.1 ± 2.1%; initial 20.9 ± 1.4%), carbon dioxide (CO₂; 25.8 ± 3.2% and 19.1 ± 02.9%, initial 1.1 ± 0.2%) and ethylene (72.3 ± 5.2 µLL-1 and 65.1 ± 4.8 µLL-1, initial 18.3 ± 2.5 µLL-1) in the headspace of the gas collection container after 30 days storage. Significant differences also for pears with and without vibrational stress in relation to soluble solids content (16.2 ± 1.2% and 17.1 ± 1.4%, initial 13.8 ± 0.8% and 14.1 ± 0.9%, respectively), weight loss (6.4 ± 0.7 g day^-1 and 5.0 ± 0.6 g day^-1), firmness (38.23 ± 7.2 kPa and 70.92 ± 13.2 kPa; initial 249.87 ± 14.8 kPa and 254.29 ± 10.7 kPa) after 30days storage. Vibration stress accelerated pear quality deterioration during storage, resulting in increased weight loss, soluble solids content, headspace CO₂ and ethylene production, and reduced hardness and headspace O₂.

A fuel cell bipolar plate having an active area of 250 mm x 250 mm was prepared using a 3D printer of Fused Deposition Modeling (FDM). The channel shape was made rectangular, and the channel's width and depth were 0.5 mm each. Altogether, 240 channels were arranged in the active area of the fuel cell bipolar plate. Three types of bipolar plates with different shapes (single type, double type, and triple type) in the bent areas were prepared. The printing speed is set to 50 mm/s, a nozzle diameter to 0.4 mm, a nozzle temperature at 200℃ and a bed temperature of 60℃. The working time of the 3D printer is about 14 hr. In the single type, filament was flown down from the end of the rib in the bent area, thereby blocking part of the channel. On the contrary, there were no blockages in the double type and triple type channels, and the shapes of the channels were produced close to the designed model. The precision of the bipolar plate channel designed as triple-type was 88.8%.

Recently, the level of exciting forces from automotive powertrains has been increased and their frequency spectra become complicated due to the weight reduction and the efficiency development. However, conventional NVH solutions have limited performances since they are focused on structural modification in order to avoid the operating range of the powertrains. In this research, the effect of passive patches on the powertrain surface will be observed via computational analyses and experimental tests. From the normal mode analysis, the location of patches will be determined. Results show that the acceleration level on the Nu engine has been decreased by 10 dB with the passive patches applied.

In this study, Al-Si coating layer of hot stamped high-strength steel plate investigated. The coating layer in hot stamped high-strength steel plate was composed of a diffusion layer and a compound layer. As the hot stamping temperature and holding time for forming increased, the thickness of the coating layer in the Al-Si coated high-strength steel plate increased. The thickness of coating layer after hot stamping with holding time of 500 sec at 890, 910 and 950℃ was obtained 8.9, 11.8, and 20.6 ㎛, respectively. The thickness of coating layer after hot stamping with holding time of 180, 500 and 850 sec at 910℃ was obtained 5.7, 11.8, and 17.8 ㎛, respectively. The compound layer consists of Al_5.4Fe₂ and Fe₂Si phases.