1,721,132 research outputs found
Fractal decoding algorithm for fast convergence
No full textA fractal coding is discussed that concentrates on relieving excessive computation burden and improving image quality in encoding. But the convergence speed of the decoder is important because, in many applications, the encoding is done once, while the decoding is to be repeated many times. Because the well-known fractal coding scheme is based on the iterated function system (IFS), we cannot avoid the iterated transformation though the scheme can be done noniteratively in a special case. Such a transformation encounters difficulty in parallel processing and hence a fast decoding algorithm is necessary. An algorithm to speedup the decoding process is described. The analysis and the simulation results of the proposed method show that our algorithm is much faster than the conventional method. (C) 1996 Society of Photo-Optical instrumentation Engineers
Effects of deposition temperature and seed layer on the optical properties of lead zirconate titanate films
No full textLead zirconate titanate (PZT) films were deposited on indium tin oxide coated Corning 7059 glass by rf magnetron sputtering at the temperatures ranging from room temperature to 500 degreesC. The crack-free PZT films with pure perovskite phase could be successfully fabricated through postannealing at 650 degreesC for 10 min. The films deposited at 400 degreesC and subsequently postannealed at 650 degreesC showed the best optical properties with a linear electro-optic coefficient of 80 pm/V and a propagation loss of 2 dB/cm. It was found from our study on the change of crystalline orientation with film thickness that the 50 nm thick PZT thin film annealed at 650 degreesC exhibited (100) preferred orientation. Using this thin film as a seed layer, we could fabricate PZT films with (100) preferred orientation that showed higher remnant polarization (2P(r) = 46 muC/cm(2)) and dielectric constant (is an element of = 1400) compared with randomly oriented films. This highly oriented PZT film also showed an excellent linear electro-optic coefficient of 109 pm/V that is comparable with the value of the PZT film epitaxially grown on the single crystal substrate. (C) 2002 American Vacuum Society.This research was supported by the Center for Electronic
Packaging Materials of Korea Science and Engineering
Foundation
New fractal coding scheme using reference images
No full textWe present a new fractal coding scheme to find more optimal transformations using reference images, which are employed as seeds for obtaining candidates for the optimal transformations. Each transformation that minimizes the distance between an original image and a reference image is a candidate. It is actually impossible to find optimal transformation due to heavy computation. Thus, instead of considering all of the allowable transformations, we select a few transformations as candidates for the optimal transformation, and thereafter select the best from that group. Our scheme can be considered a "generalized collage coding scheme," since its process for each reference image is similar to the collage coding process. That is, the collage coding scheme is a special case in our scheme, with only one reference image. At first, in a simple case where the optimal transformation can be obtained, our scheme is experimentally evaluated, as compared with the optimal one. In general cases where the optimal one is unavailable, our scheme is also evaluated compared to conventional schemes. (C) 2001 Society of Photo-Optical Instrumentation Engineers
Monolayers of poly(alpha,beta-aspartic acid) with long alkyl chains and miscibility with L-alpha-phosphatidylcholine at air-water interface
No full textSurface pressure/area isotherms of polypeptides modified with long alkyl chains and their miscibility with DPPC were investigated. The modified polypeptides formed stable monolayers due to their hairy-rod structure and limiting area increased as the degree of substitution increased. Collapse pressure of mixed monolayers deviated from ideal mixture and the free energies of mixing were negative values in all composition
Thermo-sensitive microparticles of PNIPAM-grafted ethylcellulose by spray-drying method
No full textThe thermo-sensitive polymer, PNIPAM-grafted ethylcellulose, was synthesized and it was confirmed by FTIR spectroscopy that PNIPAM was successfully grafted onto ethylcellulose. Microparticles were prepared by the spray-drying method using a B-191 Mini Spray Dryer. Their morphology, observed by scanning electron microscopy (SEM), showed irregular spheres with rugged surfaces, and narrow size distribution. In a model delivery system, ethylcelullose-g-PNIPAM was used as the polymer wall material and allopurinol was used as the model drug. The release rate of allopurinol from ECGPN8 microparticles was slower at 40degreesC (above the LCST) than that of 25degreesC (below the LCST), probably due to the collapse of PNIPAM chains by temperature. Although PNIPAM was the large part of wall material, the thermo-sensitive release behavior was not so obvious. It is believed that the release of allopurinol from the microparticles is more dependent on the porous structure of microparticles than the conformational change of PNIPAM, created by the rapid evaporation of solvent during the spray-drying process
Object based fractal coding
No full textWe present an object-based fractal coding scheme based on the partitioned iterative function system (PIFS) that is similar to the standard fractal image coding schemes. The partitioned blocks in our object-based fractal coding scheme are classified as boundary blocks and internal blocks according to their shapes. The boundary blocks are located in the boundary region of an object and their shapes are arbitrary, whereas the internal blocks are located in the internal region of an object and their shapes are square. As the internal blocks do not affect the blocks to appear in the process of the ordinary fractal coding except that the domain pool is not an image but an object, encoding for the internal blocks follows the ordinary fractal coding schemes as they are. However, the boundary blocks should be carefully handled, as they have properties that make them different from the internal blocks, i.e., they have arbitrary shapes and their domain pool is composed of the internal blocks not the boundary blocks. Considering these properties, we propose three methods to encode the boundary blocks by making an alteration to the shapes of range blocks and domain blocks, and a method to encode them using the predecoded internal blocks. The methods are mathematically analyzed and their performance is experimentally evaluated. (C) 1999 Society of Photo-Optical Instrumentation Engineers. [S0091-3286(99)01412-9]
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