Mutual Coupling Considerations in the Development of Multi-feed Antenna Systems

In the design of any multi-port network with more than one antenna, mutual coupling between these different ports must be accounted for. In an effort to investigate and control these mutual coupling effects, we have selected three structures to be thoroughly analyzed. Furthermore, they have been fabricated and tested to develop relevant design guides for these selected structures to have minimal mutual coupling effects. These selected structures included a feed network for a multi-port antenna, a dual feedhorn for a large reflector antenna, as well as a set of Multi- Input Multi-Output (MIMO) laptop antennas. In the first study, we analyzed a 30- port radial splitter that can be used for an in-phase feeding of a 30-high power transmitter. Our objectives here have been geared towards estimating the mutual coupling between the 30 ports and exploring the port and alignment failure analysis, its graceful degradation results, and relevant efficiency performance for such high power multi-port network will be presented. In the second study, we investigated the mutual coupling of a multifeedhorn structure of a large reflector antenna in order to allow multi-beam radiation or reception. This high gain antenna utilizes integrated feeds with precise physical tight spacing and could suffer from strong inter-coupling. Mutual coupling effects here include input match deterioration, beam width broadening, and cross-polarization degradation due to the proximity coupling of these various feeds. Our study derived accurate feed location expressions as well as methods to improve the decoupling between the feeds that have been implemented. These results will be discussed. For the third study, we carried out extensive investigates into the mutual coupling effects amidst wireless laptop antennas for a MIMO system implementation. For a laptop use, it is required to determine the best location, optimum spacing, and orientations of these antennas in order to achieve the maximum benefits of the system’s diversity. First, we studied the coupling between two antennas as a function of their spacing, types, and orientations. Subsequently, we extended the study to a controlled multi-antenna system for a MIMO implementation. Design rules for such implementation have been derived and will be discussed in detail

Agrobacterium Tumefaciens - Mediated Transfer of Plant DNA for Gene Expression Analysis.

Agrobacterium tumefaciens causes crown gall tumor primarily in dicotyledonous plants. The infection mechanism reveals that a portion of bacterial DNA (T-DNA) is transferred into the plant nuclear genome. This transformation system is widely utilized in plant genetic engineering and plant molecular biology. In this dissertation, two experiments were carried out. First, the copy number, physical structure and F1 segregations of T-DNA copies were analyzed, attempting to understand the mode of T-DNA integration into the plant genome. While the mechanism of Agrobacterium response to plant signals and generation and transfer of T-DNA intermediates through actions of virulence genes is generally understood, the steps leading to the integration of T-DNA into the plant genome are not understood. Toward that understanding, it was essential to investigate the physical and genetic characteristics of the transferred T-DNA within a plant genome. This study, analyzing 75 transgenic tobacco plants, indicated that T-DNAs were present from one copy to a few copies per genome and one to several chromosomal loci were integrated with T-DNA. Second, vacuole targeting signal of a seed storage protein phaseolin from Phaseolus vulgaris was investigated. Seed storage proteins, comprising approximately 50% of the total protein of the seed, are known to be synthesized in the cytoplasm and transported into vacuole protein bodies. However, the protein signal necessary for the vacuole targeting is not known. Recent studies with yeast have suggested that the targeting signal may be within the polypeptide domain of the seed storage protein. In this study, a probable targeting signal of phaseolin was constructed and then tested in transgenic tobacco plants. A reporter protein, GUS, was translationally fused to seven different lengths of DNA encoding phaseolin protein sequence. These constructions were cloned into a pTJS plant transformation vector. The vacuole targeting of the GUS protein will be investigated to identify the putative vacuole targeting signal of phaseolin

Income Distribution and Public Transfers as Social Safety Nets in Korea

Using 5-year balanced household panel data, this paper shows that the inequality of per capita income in Korea aggravated during the financial crisis in 1998. The decomposition analysis of income inequality by factor component shows that the dominant positive effect on the income inequality is by the asset income. Next is the wage income, followed by the other income. Furthermore, this paper shows that social safety net programs were not yet in place during the initial period of the crisis. Public transfers were not effective social safety net devices and did not contribute in decreasing income inequality. Private transfers, on the other hand, were effective devices and narrowed the disparity in household income.

The Octonions

The octonions are the largest of the four normed division algebras. While somewhat neglected due to their nonassociativity, they stand at the crossroads of many interesting fields of mathematics. Here we describe them and their relation to Clifford algebras and spinors, Bott periodicity, projective and Lorentzian geometry, Jordan algebras, and the exceptional Lie groups. We also touch upon their applications in quantum logic, special relativity and supersymmetry.Comment: 56 pages LaTeX, 11 Postscript Figures, some small correction

Statistical Analysis of the Metropolitan Seoul Subway System: Network Structure and Passenger Flows

The Metropolitan Seoul Subway system, consisting of 380 stations, provides the major transportation mode in the metropolitan Seoul area. Focusing on the network structure, we analyze statistical properties and topological consequences of the subway system. We further study the passenger flows on the system, and find that the flow weight distribution exhibits a power-law behavior. In addition, the degree distribution of the spanning tree of the flows also follows a power law.Comment: 10 pages, 4 figure