• Title/Summary/Keyword: I-Cube

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Range-based Cube Partitioning for Reducing I/O Cost in Cube Computation (큐브 계산에서 I/O 비용을 줄이는 구간 기반 큐브 분할)

  • Park, Woong-Je;Chung, Yon-Dohn;Kim, Jin-Nyoung;Lee, Yoon-Joon;Kim, Myoung-Ho
    • Journal of KIISE:Databases
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    • v.28 no.4
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    • pp.596-605
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    • 2001

  • In this paper we propose a method, called the range-based cube partitioning (RCP)method for reducing I/O cost of cube computation in OLAP The method improves I/O performance of cube partitioning process by overlapping some computation between partitioning stages. For overlapping the computation, the method partitions the cube based on the ranges of attribute values, not the points of attribute value, Through analysis any experiments, we show the performance of the proposed method with comparison of the previous cube partitioning method.

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Microstructure Evolution of Semi Solid AZ31+(Ca) Magnesium Alloys during Reheating Process (Ca첨가 반응고 AZ31 마그네슘 합금의 재가열에 따른 미세조직 변화)

  • Kim, Hee-Kyung;Seong, Bong-Hak;Van, Guen-Ho;Kim, Dae-Hwan;Seong, Yeong-Rok;Lim, Su-Gun
    • Journal of Korea Foundry Society
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    • v.32 no.2
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    • pp.75-80
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    • 2012

  • In this study, we are aimed to prevent grain growth of semi-solid AZ31 magnesium alloys during reheating process. The semi-solid AZ31+(Ca) billets were investigated by using metallographic analysis, X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy in order to elucidate the effect of Ca addition during reheating process. The grain growth of semi-solid AZ31+(Ca) billet was reduced with increasing Ca content during reheating. The grain size of AZ31+(Ca) billet decreased with increasing volume fraction of Al2Ca particles. The grain growth rate constant K calculated by Oswald ripening LSW theory in AZ31+1.5wt.% Ca billet was the lowest 129.

  • https://doi.org/10.7777/jkfs.2012.32.2.075 인용 PDF KSCI

The Microstructural Evolution of Mg-10Al-Mn Alloy by Cooling Plate During Homogenization Treatment (냉각판법에 의한 Mg-10Al-Mn 합금의 균질화 처리에 따른 미세조직 변화)

  • Kim, Dae-Hwan;Choi, Seung-Hwa;Kim, Hee-Kyung;Shim, Sung-Young;Lim, Su-Gun
    • Journal of Korea Foundry Society
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    • v.30 no.6
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    • pp.235-240
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    • 2010

  • The evolution of microstructure and phases of Mg-10Al-Mn alloy by cooling plate method during homogenization treatment have been investigated with metallographic analysis, scanning electron microscopy and energy dispersive spectroscopy. The ingots used for this experiment were prepared by cooling plate and homogenization heat treatment was performed at 300 and $400^{\circ}C$ for various holding times (0, 1, 4, 8 and 12h). The casting ingots were consisted of the fine grains and eutectic phases. And, these eutectic phases were dissolved into the matrix during homogenization treatment at $400^{\circ}C$ but the lower temperature (at $300^{\circ}C$) did not be.

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Environmental test campaign of a 6U CubeSat Test Platform equipped with an ambipolar plasma thruster

  • Stesina, Fabrizio;Corpino, Sabrina;Borras, Eduard Bosch;Amo, Jose Gonzalez Del;Pavarin, Daniele;Bellomo, Nicolas;Trezzolani, Fabio
    • Advances in aircraft and spacecraft science
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    • v.9 no.3
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    • pp.195-215
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    • 2022

  • The increasing interest in CubeSat platforms ant their capability of enlarging the frontier of possible missions impose technology improvements. Miniaturized electrical propulsion (EP) systems enable new mission for multi-unit CubeSats (6U+). While electric propulsion systems have achieved important level of knowledge at equipment level, the investigation of the mutual impact between EP system and CubeSat technology at system level can provide a decisive improvement for both the technologies. The interaction between CubeSat and EP system should be assessed in terms of electromagnetic emissions (both radiated and conducted), thermal gradients, high electrical power management, surface chemical deposition, and quick and reliable data exchanges. This paper shows how a versatile CubeSat Test Platform (CTP), together with standardized procedures and specialized facilities enable the acquisition fundamental and unprecedented information. Measurements can be taken both by specific ground support equipment placed inside the vacuum facility and by dedicated sensors and subsystems installed on the CTP, providing a completely new set of data never obtained before. CTP is constituted of a 6U primary structure hosting the EP system, representative CubeSat avionics and batteries. For the first test campaign, CTP hosts the ambipolar plasma propulsion system, called Regulus and developed by T4I. After the integration and the functional test in laboratory environment, CTP + Regulus performed a Test campaign in relevant environment in the vacuum chamber at CISAS, University of Padua. This paper is focused on the test campaign description and the main results achieved at different power levels for different duration of the firings.

  • https://doi.org/10.12989/aas.2022.9.3.195 인용 KSCI