• 제목/요약/키워드: I-Cube

검색결과 173건 처리시간 0.033초

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

  • 박웅제;정연도;김진녕;이윤준;김명호
    • 한국정보과학회논문지:데이타베이스
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    • 제28권4호
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    • pp.596-605
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    • 2001

  • 본 논문은 OLAP에서의 I/O 비용을 줄이는 큐브 계산 방법으로, 구간 기반 큐브 분할 기법을 제안한다. 제안하는 방법은 큐브 분할 단계들 사이에 존재하는 계산의 일부를 중복시켜 처리하는 방법을 통해 큐브 분할 작업의 I/O 성능을 향상시킨다. 계산의 중복을 위하여 제안하는 방법은 애트리뷰트의 단 일 값이 아닌 애트리뷰트 값의 일정 구간을 기준으로 큐브를 분할한다 분석과 실험을 통하여 제안하는 방법의 성능을 기존 큐브 분할 방법과 비교하여 보인다.

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

  • 김희경;성봉학;반근호;김대환;성영록;임수근
    • 한국주조공학회지
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    • 제32권2호
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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

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

  • 김대환;최승화;김희경;심성용;임수근
    • 한국주조공학회지
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    • 제30권6호
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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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    • 제9권3호
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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