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hot Data Identification with Multiple Bloom Filters： Block-Level Decision vs I/O Request-Level Decision

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Journal of Computer science & Technology 2018年第1期33卷 79-97页

作者： Dongchul park Weiping he h. C. Du Division of Computer and Electronic systems Engineering Hankuk University of Foreign Studies Gyeonggi-do 17035 Korea Intel Corporation Hillsboro OR 97124 U.S.A. Dell storage Eden Prairie MN 55344 U.S.A. Department of Computer science and Engineering University of Minnesota-Twin Cities Minneapolis MN 55455 U.S.A.

hot data identification is crucial for many applications though few investigations have examined the subject. All existing studies focus almost exclusively on frequency. however, effectively identifying hot data requires equally considering recency and frequency. Moreover, previous studies make hot data decisions at the data block level. such a fine-grained decision fits particularly well for flash-based storage because its random access achieves performance comparable with its sequential access. however, hard disk drives （hDDs） have a significant performance disparity between sequential and random access. Therefore, unlike flash-based storage, exploiting asymmetric hDD access performance requires making a coarse-grained decision. This paper proposes a novel hot data identification scheme adopting multiple bloom filters to efficiently characterize recency as well as frequency. Consequently, it not only consumes 50% less memory and up to 58% less computational overhead, but also lowers false identification rates up to 65% compared with a state-of-the-art scheme. Moreover, we apply the scheme to a next generation hDD technology, i.e., shingled Magnetic Recording （sMR）, to verify its effectiveness. For this, we design a new hot data identification based sMR drive with a coarse-grained decision. The experiments demonstrate the importance and benefits of accurate hot data identification, thereby improving the proposed sMR drive performance by up to 42%.

关键词： hot data bloom filter shingled magnetic recording (sMR)

Effects of Weaving Laser on Weld Microstructure and Crack for Al 6k21-T4 Alloy

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Journal of Materials science & Technology 2011年第1期27卷 93-96页

作者： B.h.Kim N.h.Kang W.T.Oh C.h.Kim J.h.Kim Y.s.Kim Y.h.park Department of Materials science and Engineering Pusan National UniversitySan30Jangjeon-dongGeumjeong-guBusan 609-735Korea Department of Materials and Components Engineering Dong-Eui UniversityBusan 614-714Korea Advanced Joining Technology Team KITECH7-47Songdo-dongYeonsu-guIncheon 406-840Korea Division for Dongnam Area Technology service KITECHJisa-dongGanseo-guBusan 618-230Korea

For Al 6k21-T4 overlap weld joint,the shear-tensile strength by using the weaving laser was improved as compared to the case of linear *** the specimen of low strength,the porosity was distributed continuously along the intersection between the plates and fusion ***,for the optimized welding condition,large oval-shaped porosities were located only in the advancing track of the concave ***,the continuity of cracks and porosities played a key role to determine the ***,the weaving width was also the important parameter to control the ***,the concave part had more significant hot and cold cracking in the weld and heat-affected zone（hAZ）,respectively,than the convex part.

关键词： Weaving laser Weld microstructure Void Al alloy

Difference in the hot Compressive Behavior and Processing Maps between the As-cast and homogenized Al-Zn-Mg-Cu(7075) Alloys

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Journal of Materials science & Technology 2016年第7期32卷 660-670页

作者： s.Y. park W.J. Kim Department of Materials science and Engineering Hongik University 72-1 Sangsu-dong Mapo-gu Seoul 121-791 Republic of Korea Advanced Fusion Process R&D Group Korea Institute of Industrial Technology 994-32 Dongchun-dong Yeonsu-gu Incheon 406-130 Republic of Korea

The deformation mechanisms and processing maps of the as-cast Al-Zn-Mg-Cu （？0？5） aluminum （AI） alloy were studied and compared with those of the homogenized 7075 Al alloy in the temperature range of 573-723 K and in the strain rate range of 10 3-10 s-1 to explore a possibility for directly using the as- cast 7075 Al alloy as a billet for hot working. The as-cast and homogenized 7075 A1 alloys had similar grain sizes and showed similar high-temperature deformation behaviors. The as-cast 7075 Al alloy, however, exhibited higher power efficiencies and smaller unstable flow regions compared to the homogenized 7075 AI alloy because of the presence of secondary phases （MgZn2） segregated at the dendritic interfaces in the as-cast microstructure, which were formed during non-equilibrium solidification. These segregated phases provided nucleation sites for dynamic recovery or continuous dynamic recrystallization, and as a result a fine and more homogeneous （sub）grain structure could be obtained from the as-cast micro- structure compared to the homogenized microstructure. The current work suggested the possibility and advantage of using as-cast microstructures for hot working of aluminum alloys with high content of solutes.

关键词： Al-based alloysProcessing maphot compressionAs-cast microstructuresegregationRecrystallization

Multiplexed electrospraying of water in cone-jet mode using a UV-embossed pyramidal micronozzle film

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Microsystems & Nanoengineering 2022年第5期8卷 247-256页

作者： Ji-hun Jeong Kwangseok park hyoungsoo Kim Inyong park Jinyoung Choi seung s.Lee Department of Mechanical Engineering Korea Advanced Institute of Science and TechnologyDaejeon 34141Republic of Korea Department of Environmental Machinery Korea Institute of Machinery and MaterialsDaejeon 34103Republic of Korea Department of Mechanical Engineering Dongshin UniversityNaju 58245Republic of Korea

The electrospraying of water in the cone-jet mode is difficult in practical applications owing to its low throughput and the electrical discharge caused by the high surface tension of water.A film with multiple dielectric micronozzles is essential for multiplexed electrospraying of water in cone-jet mode without electrical ***,a pyramidal micronozzle film with five nozzles was fabricated using the UV-embossing *** pyramidal micronozzle film consisted of pyramidal micronozzles,a micropillar array,and an in-plane extractor,which were proposed to minimize wetting and concentrate the electric field to the water meniscus at the tip of the pyramidal *** electrospraying of water using a single pyramidal micronozzle was visualized by a high-speed camera at a flow rate of 0.15–0.50ml/h with voltages of 0.0–2.3 kV,−1.6 kV,and−4.0 kV at the water,guide ring,and collector,*** distinct modes,the dripping,spindle,and cone-jet modes,were observed and distinguished according to the motion of the water meniscus at the nozzle *** steady Taylor cone and jet were observed in a voltage range of 1.3–2.0 kV in water,particularly in cone-jet *** electrospraying of water in cone-jet mode at a flow rate of 1.5ml/h was performed using a pyramidal micronozzle film,demonstrating the potential for a high-throughput electrospraying system.

关键词： process. film pyramidal

Influence of alloying elements on microstructure and microhardness of Mg-sn-Zn-based alloys

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Transactions of Nonferrous Metals society of China 2010年第12期20卷 2246-2252页

作者： W. L. ChENG s. park W. N. TANG B. s. YOU B. h. KOO school of Nano ＆ Advanced Materials Engineering Changwon National University Changwon 641-773 South Korea Light Metals Research Group Korea Institute of Materials Science （KIMS） Changwon 641-831 South Korea

The phase evolution in （88%-91%）Mg-8%sn-l%Zn-X （X=A1, Mn and/or Ce） system was analyzed via CALPhAD method and simulations were used in precise selection of the chemical composition. The influence of the addition of different alloying elements such as A1, Mn and Ce on the microstructure and microhardness of Mg-8%sn-l%Zn-based alloys was investigated. Combined addition of A1 and Mn shows features distinct from separate addition of A1 or Mn. Additions of l%AI and l%Mn to base alloy result in the formation of massive A1-Mn phase in a-Mg matrix grains. Addition of Ce element can refme the second eutectic precipitates and form intermetallic compounds with sn. Fine rod-like sn-Ce phase presents mainly on the grain boundaries and plays a role in inhibiting grain growth. The effects of alloying elements on Vickers microhardness and indentation size effect of base alloy were examined.

关键词： magnesium alloys alloying elements CALPhAD method hardness indentation size effect

Liquid-liquid extraction and separation of total rare earth(RE) metals from polymetallic manganese nodule leaching solution

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Journal of Rare Earths 2015年第2期33卷 207-213页

作者： P.K.Parhi K.h.park C.W.Nam J.T.park Mineral Resources Research Division Korea Institute of Geoscience & Mineral Resources (KIGAM)Daejeon 305-350 Republic of Korea school of Applied science and Center of Industrial Technology KIIT UniversityBhubaneswar 751024 Odisha India

The study on the solvent extraction for quantitative and selective separation of total rare earth metals from the polymetallic nodule leach liquor was investigated. The typical leach liquor bearing 0. 094 g/L total rare earth, 0. 23 g/L Mn, 0.697 g/L Cu, 0.2 g/L Fe, 0.01 g/L Co and 0.735 g/L Ni was subjected to the removal iron content by precipitation method using Ca（Oh）2 at ph 3.95, prior to solvent extraction of rare earth metals. Three different organo-phosphoric acid reagents（D2EhPA, PC88 A, Cyanex 272） were used to ascertain their performances and selectivity towards the loading of rare earth metals in presence of other base metals. Based on the results of eq. ph effect, the performances of above three extractants followed the order as： D2EhPA〉PC88A〉Cyanex 272. To ensure the absence of extraction of base metals（Cu, Co, Ni）, the eq. ph of the solution was optimized at the level of 2.21, though higher rare earth metal extraction efficiency was observed at higher eq. ph with either of the extractants. The complete process flow diagram for substantial recovery of total rare earth was developed using D2 EhPA. Extraction isotherm plot was constructed at A：O=12：1, 3-stages and phe=2.21, using 0.8 mol/L D2 EhPA and the predicted condition of this study was further confirmed by 6-Cycles Counter Current simulation（CCs） study. The stripping of total rare earth from loaded organic phase（LO） was conducted using hCl solution. Mc-Cabe Thiele diagram study carried out at A：O=1：5 using 4 mol/L hCl showed that three theoretical stages were needed for quantitative stripping of total rare earth. The subsequent stripped solution resulted thus led to contain total rare earth of 5.6 g/L indicating a very high enrichment of total metals by solvent extraction（sX） process.

关键词： total rare earth (RE) metals sX D2EhPA hCl deep sea nodule

肺腺癌的体积倍增时间：主要组织学亚型与预后之间的关系

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国际医学放射学杂志 2020年第4期 492-493页

作者： s.park s.M.Lee s.Kim J.G.Lee s.Choi K.h.Do 吴珺 Department of Radiology and Research Institute of Radiology University of Ulsan College of Medicine Asan Medical Center

体积倍增时间(VDT)是区分侵袭性肿瘤与缓慢生长肿瘤的一个主要参数。原发性肺腺癌的不同组织亚型的VDT如何变化及此种变化的预后价值都是未知的。目的研

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A simulation-based method to investigate occupant-centric controls

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Building simulation 2021年第4期14卷 1017-1030页

作者： Mohamed M.Ouf June Young park h.Burak Gunay Department of Building Civil and Environmental EngineeringConcordia University1515Rue Sainte-Catherine O.MontrealQCH3G 1MCanada Department of Civil Engineering The University of Texas at ArlingtonArlingtonTX76019USA Department of Civil Engineering Carleton University1125 Colonel By DriveOttawaONK1S 5B6Canada

Occupant-centric control (OCC) strategies rely on different algorithms to learn and predict occupants’ patterns and preferences, then utilize these predictions to optimize building operations. however, testing different OCC algorithms or fine-tuning their configurations in real buildings can be a lengthy process. To this end, we present a framework for testing OCCs in a simulation environment prior to field implementation. The proposed workflow entails using synthetic occupant behaviour models and simulating OCC strategies to learn their preferences. The goal is to enable quick comparison of different OCC configurations under various scenarios by modifying occupant behaviour assumptions, as well as climate and design parameters. For proof-of-concept, the proposed method was applied in a case-study to simulate OCCs for lighting and heating/cooling setpoint adjustments in a single office under various occupant types, as well as OCC settings and design configurations. Results demonstrated the benefits of the proposed framework and its potential for providing a more holistic evaluation of OCCs under different scenarios. Using the proposed framework, building designers and operators can identify potential issues with OCCs and fine-tune their settings prior to field implementation.

关键词： occupant-centric controls building simulations energy efficiency comfort building operations lighting hVAC controls

Importance of surface oxide for the tribology of a Zr-based metallic glass

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Friction 2017年第1期5卷 115-122页

作者： s.J.KANG K.T.RITTGEN s.G.KWAN h.W.park R.BENNEWITZ A.CARON Department of Materials sciences and Engineering Zhejiang University Hangzhou 310058 China NM-Leibniz Institute for New Materials Campus D2.2 Saarbrücken 66123 GermanyDepartment of Physics Saarland University Saarbrücken 66123 Germany KoreaTech Korea University of Technology and Education Chungnam Province 330-708 Republic of Korea NM-Leibniz Institute for New Materials Campus D2.2 Saarbrücken 66123 GermanyKoreaTech Korea University of Technology and Education Chungnam Province 330-708 Republic of Korea

Thermally grown surface oxide layers dominate the single-asperity tribological behavior of a Zr60Cu30Al10 *** in oxidation time leads to an increased contribution of shearing and a corresponding decreased contribution of ploughing to *** change in the dominating friction and wear mechanism results in an overall minor decrease of the friction coefficient of oxidized surfaces compared to the metallic glass sample with native surface *** results demonstrate the importance of creating a stable oxide layer for practical applications of metallic glasses in micro-devices involving sliding contact.

关键词： metallic glasses surface oxide friction wear nanotribology atomic force microscopy