• Journal of Information Processing Systems
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• v.9 no.4
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• pp.511-537
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• 2013

Numerous data intensive applications demand the efficient processing of a new type of query, which is called a progressive query (PQ). A PQ consists of a set of unpredictable but inter-related step-queries (SQ) that are specified by its user in a sequence of steps. A conventional DBMS was not designed to efficiently process such PQs. In our earlier work, we introduced a materialized view based approach for efficiently processing PQs, where the focus was on selecting promising views for materialization. The problem of how to efficiently find usable views from the materialized set in order to answer the SQs for a PQ remains open. In this paper, we present a new index technique, called the Dynamic Materialized View Index (DMVI), to rapidly discover usable views for answering a given SQ. The structure of the proposed index is a special ordered tree where the SQ domain tables are used as search keys and some bitmaps are kept at the leaf nodes for refined filtering. A two-level priority rule is adopted to order domain tables in the tree, which facilitates the efficient maintenance of the tree by taking into account the dynamic characteristics of various types of materialized views for PQs. The bitmap encoding methods and the strategies/algorithms to construct, search, and maintain the DMVI are suggested. The extensive experimental results demonstrate that our index technique is quite promising in improving the performance of the materialized view based query processing approach for PQs.

• Clean Technology
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• v.18 no.1
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• pp.38-42
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• 2012

Photonic crystals (PCs) are highly ordered porous materials which have been much attention because of its potential for controlling the light sauces. There are many methods for synthesizing this kind of materials among them we chose the supercritical deposition. With this method the reactants can easily infiltrate into the complex structure. In this paper, supercritical carbon dioxide ($scCO_2$) was used as a reaction medium, which is known as a sustainable solvent due to its nontoxic and noninflammable characteristics. We coated the colloidal template with metal alkoxide by using $scCO_2$ and then obtained macro-porous inverse opals. The reaction was carried out at $40^{\circ}C$ and 80 bar. We synthesized two different inverse opals which called silica and titania inverse opals by use of tetraethyl orthosilicate (TEOS) and titanium isopropoxide (TTIP) as a precursor, respectively.

• Bulletin of the Korean Chemical Society
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• v.31 no.12
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• pp.3593-3599
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• 2010

In an original effort, this lab attempted to employ polystyrene nanoparticles as a template for the synthesis of ordered and highly porous macroporous $SiO_2$ thin films, utilizing their high combustion temperature and narrow size distribution. However, polystyrene nanoparticle thin films were not obtained due to the low interaction between individual particles and between the particle and silicon substrate. However, polystyrene-polyacrylic acid (PS-AA) colloidal particles of a core-shell structure were synthesized by a one-pot miniemulsion polymerization approach, with hydrophilic polyacrylic acid tails on the particle surface that improved interaction between individual particles and between the particle and silicon substrate. The PS-AA thin films were spin-coated in the thickness ranges from monolayer to approximately $1.0\;{\mu}m$. Using the PS-AA thin films as sacrificial templates, macroporous $SiO_2$ thin films were successfully synthesized by vapor deposition or conventional solution sol-gel infiltration methods. Inspection with field emission scanning electron microscopy (FE-SEM) showed that the macroporous $SiO_2$ thin films consist of interconnected air balls (~100 nm). Typical macroporous $SiO_2$ thin films showed ultralow refractive indices ranging from 1.098 to 1.138 at 633 nm, according to the infiltration conditions, which were confirmed by spectroscopy ellipsometry (SE) measurements. This research shows how the synthetic control of the macromolecule such as hydrophilic polystyrene nanopaticles and silicate sol precursors innovates the optical properties and processabilities for actual applications.

• The Research Journal of the Costume Culture
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• v.19 no.4
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• pp.836-850
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• 2011

The modern fashion photograph is interpreted as diverse versions via individual perspectives and thus induces meaning as individuals compose diverse worlds. The researcher perceived the act of reading the significance of the modern fashion photograph from the aspect of the diverse worlds that the receivers comprise, and the researcher sought to highlight this with the ways of worldmaking, as in Nelson Goodman's concept of irrealism. This study sought the transitional structure of the significance of fashion photographs through the irrealism of Goodman and theoretically considered the way in which the worldmaking was organized. The study collected fashion photos shown in fashion magazines and fashion brand catalogs from 2005 to 2010 for a study of the precedent theories and a survey of photographic materials to select characteristics based on Goodman's Ways of Worldmaking. Goodman suggested the five ways of composition and decomposition, deformation, weighting, deletion and supplementation, and ordering as the ways of worldmaking. The composition and decomposition way leads to habit and perpetuation due to existing concepts or intimateness. It can also be considered that the composition and the decomposition way occur coincidentally with other ways due to the previous worlds in which users connote during the process through which the fashion photos were composed and decomposed, deformed, weighted, and ordered. Therefore, this study researched the four ways of composition and decomposition, deformation, weighting, and ordering by integrating them into fashion photos based on the five types of ways reviewed through a theoretical consideration.

• Journal of Magnetics
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• v.7 no.1
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• pp.18-20
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• 2002

The charge structures of (LSMO) and of the combined system $(La_{ 0.6}Sr_{0.4}FeO_3$(LSMO) and of the combined system (La_{0.6}Sr_{0.4}MnO_3)_{0.7}(La_{0.6}Sr_{0.4}/FeO_3)_{0.3}$are investigated by using M$\ddot{o}$ssbauer spectroscopy. The antiferromagnetically ordered $(La_{0.6}Sr_{0.4}FeO_3$(LSFO) has possible charges of Fe^{3+} and Fe^{4+}$, which include a low-spin $Fe^{4+}$ state at and above 230 K. The temperature dependences of the M$\ddot{o}$ssbauer spectra for the $(La_{ 0.6}Sr_{0.4}FeO_3$ system and for the combined $(LSMO)_{ 0.7}(LSFO)_{0.3}$ system are fitted as three sets of Zeeman patterns corresponding to $Fe^{3+}$ and $Fe^{4+} below 230 K. At and above 230 K, the fitted M$\ddot{o}$ssbauer spectra for the combined system are the same in all temperature ranges. Above 230 K, $(La_{0.6}Sr_{0.4}FeO_3$ spectrum consists of two sets of six Lorentzians for $Fe^{3+}$ and one line for low spin $Fe^{4+}$. It is worth noting that large fields are induced in the combined system.

• Journal of the Korean Ceramic Society
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• v.52 no.5
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• pp.366-373
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• 2015

Sol-gel binder was prepared by hydrolysis and condensation reaction using boehmite sol and methyltrimethoxysilane as a function of aging-time. The coating slurry was composed of a plate-shape alumina in the sol-gel binder for the EPD process, in which particles dispersed in the slurry were deposited on the electrode under an electric field due to the surface charge. We studied the effects of three parameters: the content of boehmite, the aging time, and the applied voltage, on the physical, thermal, and electrical properties of the hybrid composite films by EPD. The amount of boehmite was 10 ~ 20 wt% and the aging time was 0.5 ~ 72, with a fixed amount of plate-shape alumina of 10 wt%. The condition of applied voltage was 5 ~ 30 V with a distance of 2 cm between the electrode during the EPD process. We confirmed that a structure of hybrid composite films of well-ordered plate alumina was deposited on the substrate when the film was prepared using a sol-gel binder composed of 15 wt% boehmite with 1 hr aging time and EPD at 10 V. The process shows a weight loss of 7% at $500^{\circ}C$ in TGA and a breakdown voltage of 8 kV at $87{\mu}m$.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.382-382
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• 2010

$TaO_2$ thin films as gate dielectrics have been proposed to overcome the problems of tunneling current and degradation mobility in achieving a thin equivalent oxide thickness. An extremely thin $SiO_2$ layer is used in order to separate the carrier in MOSFETchannel from the dielectric field fluctuation caused by phonons in the dielectric which decreases the carrier mobility. The electronic and optical properties influenced the device performance to a great extent. The atomic structure of amorphous and crystalline Tantalum oxide ($TaO_2$) gate dielectrics thin film on Si (100) were grown by utilizing atomic layer deposition method was examined using Ta-K edge x-ray absorption spectroscopy. By using X-ray photoelectron spectroscopy and reflection electron energy loss spectroscopy (REELS) the electronic and optical properties was obtained. In this study, the band gap (3.400.1 eV) and the optical properties of $TaO_2$ thin films were obtained from the experimental inelastic scattering cross section of reflection electron energy loss spectroscopy (REELS) spectra. EXAFS spectra show that the ordered bonding of Ta-Ta for c-$TaO_2$ which is not for c-$TaO_2$ thin film. The optical properties' e.g., index refractive (n), extinction coefficient (k) and dielectric function ($\varepsilon$) were obtained from REELS spectra by using QUEELS-$\varepsilon$(k, $\omega$)-REELS software shows good agreement with other results. The energy-dependent behaviors of reflection, absorption or transparency in $TaO_2$ thin films also have been determined from the optical properties.

• Applied Chemistry for Engineering
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• v.31 no.2
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• pp.215-219
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• 2020

In this study, nanoporous iron oxide layers were fabricated by the anodization of 304 series stainless steel. K₂HPO₄/glycerol solution was used as an electrolyte for anodization. We investigated the anodization behavior according to various parameters such as electrolyte concentration, reaction temperature, applied voltage, and reaction time. As a result of anodization, we confirmed that the anodic growth rate of oxide layer on 304 series stainless steel increased with increasing the electrolyte temperature and applied potential. In order to form well-ordered porous nanostructures, the electrolyte temperature was at 160 ℃, and the applied potential was at 30 V in 10 wt% K₂HPO₄/glycerol electrolyte.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.87-87
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• 2010

Adsorption and subsequent catalytic reactions of ethanol and acetaldehyde on chemically modified rutile TiO2(001) surfaces are probed by x-ray photoemission spectroscopy (XPS) using synchrotron radiation. TiO2 is a well-known photocatalyst for various catalytic reactions including oxidation of organic molecules. In this respect, the surface atomic structure has been found to play a vital role in determining the catalytic reactivity and selectivity of TiO2. In this study, we employ an atomically well-ordered reduced TiO2(001) surface which is prepared in a UHV chamber by repeated Ar+-sputtering and annealing (900 K) cycles. We systematically modify the surface by treating the surface with H2O or O2 at room temperature (RT). The catalytic reactivity of the surface-modified TiO2(001) is evaluated by dosing ethanol/acetaldehyde onto the surface at RT and by subsequent annealing to higher temperatures (400~600 K). XPS spectra of C 1s core level are intensively used to probe any change in the oxidation state of carbon atoms. We find that the reactivity as well as the saturation coverage are significantly affected by the RT-treatment of the TiO2 surface with H2O or O2. For both reactant molecules (ethanol/acetaldehyde), oxidation reactions are found to be enhanced on the O2-treated surface compared with the reduced or H2O-treated surfaces. Possibly reaction pathways are discussed based on the observed XPS spectra.

• Polymer(Korea)
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• v.35 no.6
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• pp.531-536
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• 2011

Homopolymer distribution in block copolymer/homopolymer blends was investigated as a function of homopolymer concentration and homopolymer molecular weight. The deuterated poly(methyl methacrylate) or polystyrene was blended with a deuterated polystyrene-poly(methyl methacrylate) diblock copolymer up to a concentration of 20 wt%. Samples were characterized by small-angle X-ray scattering (SAXS), neutron reflectivity and transmission electron microscopy. The block copolymer with a thin-film geometry formed alternating lamellar microdomains oriented parallel to the substrate surface. By adding the homopolymer, the microdomain structure was significantly disturbed. As a consequence, a poorly ordered morphology appeared when the homopolymer concentration exceeded 15 wt%. Increasing the homopolymer concentration and/or the homopolymer molecular weight caused the microdomains to swell less uniformly, resulting in segregation of the homopolymer toward the middle of the microdomains.