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A membrane material based on polyamide-imide (PAI) has received a great attention lately due to its thermal resistance, outstanding mechanical property, and low thermal expansion coefficient. In this study, we have focused on the preparation of porous PAI nanofiber membranes (PNMs) for water treatments. The preparation of PNMs was completed via the electrospinning method using PAI in a mixed solvent of dimethylacetamide and tetrahydrofuran. The resulting PNMs were then thermally treated to improve mechanical properties. These PAI-based membranes were characterized by scanning electron microscope, tensometer (tensile strength and elongation), pore characteristic, contact angle analyzer (contact angle), and dead-end cell device (water flux). We noticed that the pore diameter (1.0–0.3 μm) of PNMs was systematically controlled by simply increasing the number of PNMs layers. As these nanofiber membranes were found to be highly hydrophobic, we also attempted to prepare hydrophilic PNMs with a PAI solut...

Objectives : The Korean government in January 2006 instigated an exemption policy for hospitalized children under the age of six years old. This study examines how this policy affected the utilization of medical care in Korea. Methods : A total of 1,513,797 claim records from the Health Insurance Review Agency were analyzed by complete enumeration methods. The changes of medical utilization were compared from 2005 to 2006. In addition, the changes of medical utilization between 2004 and 2005 were compared as a pseudo-control group. Results : The admission rate increased 1.14-fold from 15.20% in 2004 to 17.32% in 2005, and this further increased 1.08-fold to 18.65% in 2006. The increase of patients with a common cold (1.2-fold) was higher than that of both the general patients (1.08-fold) and the patients, with the top 10 fatal diseases (0.91-fold). The average length of stay per case for clinics showed the highest increase rates (1.06-fold). The rates of patients with the common cold showed a higher increase (1.05-fold) than that of the general patients. The average medical expense per case was increased by 1.10-fold from 2005 to 2006, which was higher than that from 2004 to 2005 (1.04-fold). The increase rate for patients with the common cold was higher at 1.18-fold than that of the general patients. Conclusions : The cost exemption policy has especially led to an increase in the utilization of clinics and the utilization by patients with a common cold.

Maskless random reactive ion etching (RIE) texturing employing a SF6/O2/Cl2 gas mixture was investigated in order to achieve higher efficiencies in multicrystalline silicon (mc-Si) solar cells. Triangular pyramid structures with an aspect ratio of 1 were formed and, when the RIE power increased, the average reflectance was reduced by about 1.46% per 10 W. This was due to the increased density of the surface features. The performances of all of the RIE-textured mc-Si solar cells were improved compared with that of the reference cell. Among them, the 110 W cell, which had a 0.6% higher efficiency than the reference cell, had the highest efficiency of 16.82%. An impedance analysis was carried out to determine series resistance (R s), shunt resistance (R sh), and junction capacitance (C j). Interestingly, the cell with higher efficiencies and higher structure densities had higher linear reverse currents.

For the fabrication of bulk near-net-shape shape memory alloys and porous metallic biomaterials, consolidation of TiNi alloy powders is more useful than that of elemental powders of Ti and Ni. In the present study, TiNi shape memory alloy powders were prepared by inert gas atomization, and martensitic transformation temperatures and microstructures of those powders were investigated as a function of powder size. The size distribution of the powders was measured by conventional sieving, and sieved powders with the specific size range of 0–200 μm were chosen for this examination. XRD analysis showed that the B2–B19' martensitic transformation occurred in powders smaller than 200 μm. In DSC curves of the as-atomized Ti50Ni50 powders as a function of powder size, only one clear peak was found on each cooling and heating curve. The martensitic transformation start temperature (Ms) of the 0–20 μm powders was 21.9 °C. The Ms increased with increasing powder size, and the difference in Ms between 0 and 20 μm powders and 150–200 μm powders is only 1 °C. The typical microstructure of the rapidly solidified TiNi powders showed cellular/dendrite morphology and exhibited a small volume fraction of Ti2Ni phase, which is located in interdendritic/intercellular regions.