Showing papers by "Kwangwoon University published in 1991"

Hopfield network application to optimal edge selection

Abstract: The goal of the present work is to plan the shortest collision-free path in 3-D, when a robot is navigated to pick up some tools or to repair some parts from various locations. To accomplish this goal, the path coordinator should have the capabilities of an obstacle avoidance strategy and a traveling salesman problem strategy (TSP). The obstacle avoidance strategy is to plan the shortest collision-free path between each pair of n locations in 2-D or in 3-D. The TSP strategy is to compute a minimal system cost of a tour that is defined as a closed path navigating each location exactly once. The TSP strategy can be implemented by a neural network. The obstacle avoidance strategy in 2-D can be implemented by the V-graph algorithm. However, the V-graph algorithm is not useful in 3-D, because it cannot compute the global optimality n 3-D. Thus, the path coordinator is proposed to solve this problem, having the capabilities of selecting the optimal edges by the modified genetic algorithm and computing the optimal nodes along the optimal edges by the recursive compensation algorithm. >

The thermally stimulated current in zinc oxide varistors with TiO/sub 2/ additives

Abstract: To contribute more information on the conduction mechanism in ZnO varistors, a study of ZnO varistors with TiO/sub 2/ additives was conducted. The properties of ZnO varistors are found to depend on the grain structure of ZnO. The mechanism of nonlinear conduction of ZnO may be explained on the basis of the grain structure. The TSC (thermally stimulated current) spectrum was measured to study the trapped carriers in ZnO varistors. Four peaks of TSC may be distinguished on the spectrum of TSC. The origin of the first, second, and third TSC peaks was attributed to the detrapping of the trapped electrons in the shallow trap, donor level, and deep trap, respectively. The origin of the fourth peak was attributed to the process of depolarization of the donor ions in the depleted layer. Adding TiO/sub 2/ to ZnO varistors caused the leakage current to increase. >

Transient response analysis of an electret microphone

Abstract: The transient response of an electret microphone without a back cavity (i.e., with no cavity below the back electrode which communicates with the air trapped between the foil and the back electrode) is analyzed by examining the motion of the electret foil in response to a transient acoustic signal applied uniformly on the foil face. The analysis uses a normal mode expansion of the motion of the circular diaphragm. A numerical evaluation of the time domain response of the electret microphone based on the analysis is pressented for the acoustic excitation by an N-wave (i.e., shock wave). Results for the N-wave show good agreement with experimental measurements. both in motion of membrane and output voltage.