Development of Optimized Compact Finite Difference Schemes

Optimized high-order compact(OHOC) schemes were proposed, which have high spatial order of truncation and resolution to simulate the aeroacoustic problems due to unsteady compressible flows. Generally, numerical schemes are categorized explicit or implicit by time-marching method. In this research, OHOC differences which were developed with explicit time-marching method is used to have implicit formulation and the implicit OHOC differences result in block hepta-diagonal matrix. This paper presents the comparisons between the explicit and implicit OHOC schemes with a second order accuracy of time in the 1-d linear wave convection problem, and between the explicit OHOC scheme of 4th-order accuracy in time and the implicit OHOC scheme of 1st-order accuracy in tine for the 1-d nonlinear wave convection problem. With these comparisons, the characteristics of implicit OHOC scheme are shown in the point of CFL number

A study on characteristics of implicit optimized compact scheme

학위논문(석사) - 한국과학기술원 : 항공우주공학과, 1999.2, [ v, 51 p. ]한국과학기술원 : 항공우주공학과

센서 네트워크에서 최저전력소모를 위한 최적의 가벼운 라우팅

학위논문(석사) - 한국정보통신대학교 : 공학부, 2005, [ vii, 66 p. ]While getting so much attention as the most promising technology that makes human environment interactions possible, wireless sensor network has been showing its tangible applications in real fields thanks to the advances in technologies such as MEMS, wireless communications, processors and so on. Among many design factors, the energy efficiency is the most crucial, Until now, there have been many trials to provide an optimal route for minimum energy consumption in wireless sensor network whose energy resource is very limited at every node. Currently, however, the mechanisms to find \It{minimum energy paths} (MEPG) do not properly take into account the efficiency in time and storage, the optimality in results, and the feasibility in real systems. In the thesis, as an useful auxiliary for the minimum energy routing protocol, we propose an efficient and first optimal algorithm to find the MEPG in which all \It{minimum energy paths} are included, not only significantly reducing its total number of edges, but also getting an optimal result in \It{O}(\It{V}\log{V+E}). In addition, the proposed algorithm can be utilized to find other types of reduced graph according to the weight values used in the graph. For example, adopting the delay as a weight value, the proposed algorithm can draw the graph having all \It{minimum delay paths} but whose total number of edges is quite less than the original graph. We also suggest \It{Power Aware Data-centric} (PAD) routing protocol characterized by minimum energy consumption, longer lifetime, and low network delay in sensor networks PAD, which makes the routing table prior to packet transmissions, is a kind of \It{Distance Vector} (DV) routing protocol, PAD is designed to perform the minimum energy routing and reduce the overheads for routing table constructions. For longer lifetime, detours can be used instead of found minimum energy paths with low overhead. In addition, the mobility is also supported with low ov...한국정보통신대학교 : 공학부