• Title/Summary/Keyword: 필러

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A Query Processing Technique for XML Fragment Stream using XML Labeling (XML 레이블링을 이용한 XML 조각 스트림에 대한 질의 처리 기법)

  • Lee, Sang-Wook;Kim, Jin;Kang, Hyun-Chul
    • Journal of KIISE:Databases
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    • v.35 no.1
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    • pp.67-83
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    • 2008

  • In order to realize ubiquitous computing, it is essential to efficiently use the resources and the computing power of mobile devices. Among others, memory efficiency, energy efficiency, and processing efficiency are required in executing the softwares embedded in mobile devices. In this paper, query processing over XML data in a mobile device where resources are limited is addressed. In a device with limited amount of memory, the techniques of XML. stream query processing need to be employed to process queries over a large volume of XML data Recently, a technique Galled XFrag was proposed whereby XML data is fragmented with the hole-filler model and streamed in fragments for processing. With XFrag, query processing is possible in the mobile device with limited memory without reconstructing the XML data out of its fragment stream. With the hole-filler model, however, memory efficiency is not high because the additional information on holes and fillers needs to be stored. In this paper, we propose a new technique called XFLab whereby XML data is fragmented with the XML labeling scheme which is for representing the structural relationship in XML data, and streamed in fragments for processing. Through implementation and experiments, XML showed that our XFLab outperformed XFrag both in memory usage and processing time.

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Effect of Nano-filled Protective Coating on Microhardness and Wear Resistance of Glass-ionomer Cements (나노필러가 함유된 표면보호재가 글라스 아이오노머 시멘트의 미세경도와 마모저항성에 미치는 효과)

  • Ryu, Wonjeong;Park, Howon;Lee, Juhyun;Seo, Hyunwoo
    • Journal of the korean academy of Pediatric Dentistry
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    • v.46 no.2
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    • pp.226-232
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    • 2019

  • The purpose of this study was to investigate the effect of adding a protective coating on the microhardness and wear resistance of glass ionomer cements (GICs). Specimens were prepared from GIC and resin-modified GIC (RMGI), and divided into 3 groups based on surface protection: (1) no coating (NC), (2) Equia coat coating (EC), and (3) un-filled adhesive coating (AD). All specimens were then placed in distilled water for 24 h. Surface hardness (n = 10) was evaluated on a Vickers hardness testing machine. Wear resistance (n = 10) was evaluated after subjecting the specimen to thermocycling for 10,000 cycles using a chewing simulator. Data were analyzed using a one-way ANOVA and the Kruskal-Wallis test. Surface hardness was highest in the NC groups, followed by the EC and AD groups. The wear depth of GI + NC was significantly higher than that of all RMGI groups. EC did not significantly lower the wear depth compared to AD. Based on these results, it was concluded that although EC does not increase the surface microhardness of GIC, it can increase the wear resistance.

  • https://doi.org/10.5933/JKAPD.2019.46.2.226 인용 PDF KSCI

Composite-Based Material and Process Technology Review for Improving Performance of Piezoelectric Energy Harvester (압전 에너지 수확기의 성능 향상을 위한 복합재료 기반 소재 및 공정 기술 검토)

  • Kim, Geon Su;Jang, Ji-un;Kim, Seong Yun
    • Composites Research
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    • v.34 no.6
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    • pp.357-372
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    • 2021

  • The energy harvesting device is known to be promising as an alternative to solve the resource shortage caused by the depletion of petroleum resources. In order to overcome the limitations (environmental pollution and low mechanical properties) of piezoelectric elements capable of converting mechanical motion into electrical energy, many studies have been conducted on a polymer matrix-based composite piezoelectric energy harvesting device. In this paper, the output performance and related applications of the reported piezoelectric composites are reviewed based on the applied materials and processes. As for the piezoelectric fillers, zinc oxide, which is advantageous in terms of eco-friendliness, biocompatibility, and flexibility, as well as ceramic fillers based on lead zirconate titanate and barium titanate, were reviewed. The polymer matrix was classified into piezoelectric polymers composed of polyvinylidene fluoride and copolymers, and flexible polymers based on epoxy and polydimethylsiloxane, to discuss piezoelectric synergy of composite materials and improvement of piezoelectric output by high external force application, respectively. In addition, the effect of improving the conductivity or the mechanical properties of composite material by the application of a metal or carbon-based secondary filler on the output performance of the piezoelectric harvesting device was explained in terms of the structure of the composite material. Composite material-based piezoelectric harvesting devices, which can be applied to small electronic devices, smart sensors, and medicine with improved performance, can provide potential insights as a power source for wireless electronic devices expected to be encountered in future daily life.

  • https://doi.org/10.7234/composres.2021.34.6.357 인용 PDF KSCI HTML