It is known that the current collected from an ionization chamber exposed to a constant radiation intensity changes in magnitude when the polarity of the collecting potential is reversed. It is called the polarity effect of the ionization chamber. There are many possible causes that induce the polarity effect and one of them can be a field distortion due to a potential difference between the guard electrode and the collector. We studied how much the polarity effect depends on the design of the electrodes in the thimble-type ionization chamber. Two thimble-type ionization chambers, which had different electrode structures, were designed and fabricated at KAERI. We calculated the field distortions due to the potential difference between the guard electrode and the collector for the two ionization chambers. MAXWELL and Garfield were employed to calculate the electron drift lines inside the chamber. The polarity effects of the two ionization chambers were measured, and they were consistent with the field calculation. We could conclude that the polarity effect is mostly induced from the field distortion due to the potential difference between the guard electrode and the collector in our experiment and it depends significantly on the design of the electrodes.

Rubber isolators are mounted between a cooling module and a carrier to isolate the car body from vibration due to the rotation of the cooling fan. The isolators should be durable against fatigue loads originating from fan rotation and road disturbance. Thus, the design of rubber isolators is required to maximize both vibration isolation and fatigue life. In this study, the shapes of the rubber isolators are optimally designed using a process integration and design optimization (PIDO) tool that integrates the various computer-aided engineering (CAE) tools necessary for vibration and fatigue analyses, automates the analysis procedure and optimizes the design solution. In this study, we use CAE models correlated to the experimental results. A regression-based sequential approximate optimizer incorporating Process Integration, Automation and Optimization (PIAnO), a commercial PIDO tool, is employed to handle numerically noisy responses with respect to the variation in design variables. Using the analysis and design procedure established in this study, we successfully obtained the optimal shapes of the rubber isolators in two different cooling modules; these shapes clearly have better vibration isolation capability and fatigue lives than those of the baseline designs used in industry.

No abstract

The paper aims to evaluate the impact response of glass/epoxy laminates with embedded shape memory alloy (SMA) subject to low velocity impact at various temperatures. For the goal, the impact tests were performed by using an instrumented impact-testing machine at three temperatures: 293K, 263K and 233K for the baseline (laminates without SMA wires) and SMA laminates (laminates with embedded SMA wires). And the resultant damages were inspected through the scanning acoustic microscope (SAM). Also, based on the impact force history and the damage configuration, the impact resistance parameters were employed to evaluate damage resistance of laminates with embedded SMA wires. As a result, it was observed that the damage resistanceof glass/epoxy laminates is influenced by embedded SMA wires and embedding SMA wires into laminates does not compromisethe structure any differently to laminates without wires. In fact, it has been shown that under lower temperature, the SMA laminates have a little superior damage resistancecompared with the baseline laminates.

No abstract