We developed a web-based program for a national surveillance system to determine baseline data regarding the supply and demand of blood products at sentinel hospitals in South Korea. Sentinel hospitals were invited to participate in a 1-month pilot-test. The data for receipts and exports of blood from each hospital information system were converted into comma-separated value files according to a specific conversion rule. The daily data from the sites could be transferred to the web-based program server using a semi-automated submission procedure: pressing a key allowed the program to automatically compute the blood inventory level as well as other indices including the minimal inventory ratio (MIR), ideal inventory ratio (IIR), supply index (SI) and utilisation index (UI). The national surveillance system was referred to as the Korean Blood Inventory Monitoring System (KBIMS) and the web-based program for KBIMS was referred to as the Blood Inventory Monitoring System (BMS). A total of 30 256 red blood cell (RBC) units were submitted as receipt data, however, only 83% of the receipt data were submitted to the BMS server as export data (25 093 RBC units). Median values were 2.67 for MIR, 1.08 for IIR, 1.00 for SI, 0.88 for UI and 5.33 for the ideal inventory day. The BMS program was easy to use and is expected to provide a useful tool for monitoring hospital inventory levels. This information will provide baseline data regarding the supply and demand of blood products in South Korea.

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To investigate die filling from a semisolid melt, a die was designed to cast a two-part test sample with restrictions in one part and steps of different thicknesses in the other. Several defect types were observed including surface eutectic segregation, gas holes with eutectic segregation, oxide flaws, and shrinkage porosity. The effect of melt injection velocity on liquid segregation in the cast parts was investigated using macro-microstructural observation and computer simulation. Process parameters to reduce liquid segregation were obtained by computer simulation. The effect of injection speed of the plunger tip on liquid segregation was most significant after the semisolid material had filled the runner. According to experimental and simulation results, liquid segregation could be removed by controlled high plunger speed (more than 0.3m/s).

Mechanical properties and microstructure of heat-treated samples of A356 and AA2024 aluminum alloys, which were rheoforged by varying the change in pressure and temperature were investigated, preventing defects such as porosity, liquid segregation, and insufficient filling occurring during rheoforging process. The rheology material was fabricated by an electromagnetic stirring process by controlling stirring current so that shearing force and temperature of the molten metal were controlled during electromagnetic stirring. As a result, by crushing dendrite and rosette type microstructures, fine and globularized rheology material was obtained and the feasibility of the rheoforging process was found to be positive. In the case of the direct rheoforging process, excessive applied forging-pressure caused material spattering, which in turn caused eutectic segregation. This segregation brought about a shrink hole and thus led to a deterioration of mechanical strength. According to varied applied forging pressures, agglomeration phenomena of primary particles of wrought aluminum alloy remarkably increased as compared with an as-cast aluminum alloy.

The weight of a bipolar plate is one of the most crucial properties from the viewpoint of improving the power density of a proton-exchange membrane fuel cell (PEMFC) stack. Aluminum alloys have good material characteristics such as low electrical resistivity, high thermal conductivity, and low density. Furthermore, they are less expensive and eas ily machinable compared to graphite when used for fabricating bipolar plates. In this study, the use of AA5052 for fabricating a bipolar plate was investigated. The results of the feasibility experiments conducted to develop fuel cells with AA5052 bipolar plates having multiple microchannels were presented. The formability of microchannels under various types of pulsating loads was estimated for different punch loads and die radii using 0.3 mm thick AA5052 sheets. For a 0.1 mm die radius, the optimum formability was obtained for five cycles of sine wave dynamic loading with a maximum load of90kN. The experimental results demonstrated the feasibility of the proposed technique for fabricat ing bipolar plates.