• Title/Summary/Keyword: lattices

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The Safety Program Plan of the LRT(Light Rail Transit) System (경량전철시스템의 안전성구축방안)

  • 정락교;윤용기;목재균;이병송;최규형
    • Proceedings of the KSR Conference
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    • 2000.11a
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    • pp.586-593
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    • 2000
  • This paper describes a safety program plan of the LRT(Light Rail Transit) project. The SPP is a management document that describes the system safety objectives and how they will achieved so it embodies principles, methods and 1)lattices commonly used in the transit industry. In a Preliminary Hazard Analysis phase, the hazard analysis of collision and derailment is carried out. In this paper we make a definition of hazard that hazard is consist of an inner part(means a reliability) and an outer part(means a fire, flood and earthquake). Also safety principles for infrastructure, stations, electric traction system, railway control of system and train are performed.

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Synthesis of Carbon-Supported Pt-Ru Catalysts using a Flame Spray Pyrolysis Method for Fuel Electrode of Low Temperature Fuel Cell (화염분무열분해 공정을 이용한 저온 연료전지 연료전극용 탄소담지 Pt-Ru 촉매의 제조)

  • Lee, Hyun-Min;Lee, Dong-Geun
    • Particle and aerosol research
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    • v.8 no.2
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    • pp.69-74
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    • 2012
  • This study describes how successfully a conventional flame aerosol synthesis was used to continuously synthesize Pt-Ru catalysts supported by carbon agglomerates. Nearly spherical catalysts produced in the flame were mainly composed of metallic Pt and Ru with the molar ratio of 1:1 and those sizes were controllable from ~1.5 nm to ~2.0 nm. Nevertheless, only Pt peaks were found from X-ray diffraction experiments, suggesting that amorphous-like Ru was well mixed in the crystalline Pt lattices. It was found from Cyclo-voltamograms and CO stripping experiments that the electrochemical properties of the catalysts are at least comparable to that of a conventional commercial sample.

Enhanced Luminescence of $SrTiO_3:Pr^{3+}$by Incorporating with $Li^+$ or $Na^+$Ion

  • Tian, Lianhua;Mho, Sun-Il;Bae, Hyun-Sook;Yu, Byung-Yong;Pyun, Chong-Hong
    • 한국정보디스플레이학회:학술대회논문집
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    • 2002.08a
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    • pp.819-821
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    • 2002
  • Photoluminescenc (PL) and low-voltage cathodoluminescence (CL) characteristics of $[xSrTiO_3+(1-x)Li_2TiO_3]:Pr^{3+}$ and $[xSrTiO_3+(1-x)Na_2TiO_3]:Pr^{3+}$ systems were investigated. The red luminescence intensities of these compounds are enhanced remarkably by the incorporation of $Li^+$ or $Na^+$ ion as compared to that of $SrTiO_3:Pr^{3+}$. The enhanced luminescence is speculated to result from both the charge compensation of $Pr^{3+}$ site and oxygen vacancies generated in the lattices by $Li^+$ or $Na^+$ ion.

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Logical Implications on Orthomodular Lattices (직교모듈라 격자에서의 논리적 함의)

  • Yon, yong-ho
    • Proceedings of the Korea Contents Association Conference
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    • 2017.05a
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    • pp.431-432
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    • 2017
  • 고전 논리의 연산이 집합의 연산과 밀접하게 관련되어 있는 것과 같이 양자논리(quantum logic)는 힐버트 공간(Hilbert space)의 닫힌부분공간(closed subspace)의 연산과 관련되어 있다. 닫힌부분공간들의 집합은 직교모듈로 격자(orthomodular lattice)를 이루고, von Neumann과 Birkhoff를 포함하여 많은 수학자들은 양자논리의 수학적 체계를 만들기 위해 직교모듈로 격자를 이용하였다. 일반 격자(lattice)에서 논리적 함의(implication)는 $x{\rightarrow}y={\neg}x{\vee}y$에 의해 일의적으로 정의되지만 직교모듈로 격자에서는 6개의 서로 다른 논리적 함의가 정의되는 것으로 알려져 있다. 본 논문에서는 직교모듈로 격자에서 정의되는 3개의 논리적 함의를 소개하고 이들 사이의 관계를 조사한다.

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Studies on Grain Size Refinement for Rheocasting of Hypereutectic Al-18% Si by Using Sieve Type Mechanical Stirrer (과공정 Al-18% Si 합금의 레올로지 성형시 기계적 교반을 이용한 입자 미세화 연구)

  • 강용기;박진욱;강성수;강충길;문영훈
    • Transactions of Materials Processing
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    • v.9 no.4
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    • pp.389-394
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    • 2000
  • The studies on gram size refinement for rheocast processing of hypereutectic Al-18%Si alloys have been investigated in the present study. To increase the efficiency of mechanical stirring, sieve type stirrer are newly designed and implemented for rheocasting of hypereutectic Al-18%Si alloy. Mechanical stirring of semi-solid slurry by using sieve type mechanical stirrer results in morphological changes of the primary Si particles, from angular rod shape to near spherical shape and uniform distribution of proeutectic Si. The remarkable spheroidization of Primary Si Particles and distributional uniformity of proeutectic Si show well the efficiency of sieve type mechanical stirring method which can accelerate the coalescence-fracture-wear of the individual particles by strong turbulent flow between lattices during rotation of sieve type stirrer.

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Surface and Interface Analysis with Medium Energy Ion Scattering Spectroscoppy

  • Moon, Dae-Wom
    • Proceedings of the Korean Vacuum Society Conference
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    • 1998.02a
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    • pp.129-129
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    • 1998
  • Most of the surface/interface analysis tools have limited depth profiling c capability in terms of the profiling range and the depth resolution. However, M MEIS can profile the surface and subsurface composition and structure q quantitatively and non-destructively with atomic layer depth resolution. I In this presentation, the MEIS system developed at KRISS will be briefly d described with an introduction on the principle of MEIS. Recent MEIS r results on the surface and interface composition and structural change due to i ion bombardment will be presented for preferential sputtering of T:없Os and d damage depth profiles of SHooD, Pt(l11), and Cu(l1D due to Ar+ ion b bombardment. Direct observation of strained Si lattices and its distribution i in the SHool)-SiCh interface and the initial stage of Co growth on Pt(l11) w will be reported. H surfactant effects on epitaxial growth of Ge on Si(ooD w will be discussed with STM results from SND.

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Lattice-based strongly-unforgeable forward-secure identity-based signature scheme with flexible key update

  • Zhang, Xiangsong;Liu, Zhenhua
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.11 no.5
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    • pp.2792-2810
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    • 2017
  • Forward-secure signature is a specific type of signature, which can mitigate the damage caused by the signing key exposure. Most of the existing forward-secure (identity-based) signature schemes can update users' secret keys at each time period, achieve the existential unforgeability, and resist against classical computer attacks. In this paper, we first revisit the framework of forward-secure identity-based signatures, and aim at supporting flexible key update at multi time period. Then we propose a post-quantum forward-secure identity-based signature scheme from lattices and use the basis delegation technique to provide flexible key update. Finally, we prove that the proposed scheme is strongly unforgeable under the short integer solution (SIS) hardness assumption in the random oracle model.

Verification of HELIOS-MASTER System Through Benchmark of Critical Experiments

  • Kim, Ha-Yong;Kim, Kyo-Youn;Oh, Cho-Byung;Lee, Chung-Chan;Zee, Sung-Quun
    • Proceedings of the Korean Nuclear Society Conference
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    • 1999.05a
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    • pp.22-22
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    • 1999
  • The HELlOS-MASTER code system is verified through the benchmark of the critical experiments that were performed by RRC "Kurchatov Institute" with water-moderated hexagonally pitched lattices of highly enriched Uranium fuel rods (8Ow/o). We also used the same input by using the MCNP code that was described in the evaluation report, and compared our results with those of the evaluation report. HELlOS, developed by Scandpower A/S, is a two-dimensional transport program for the generation of group cross-sections, and MASTER, developed by KAERI, is a three-dimensional nuclear design and analysis code based on the two-group diffusion theory. It solves neutronics model with the AFEN (Analytic Function Expansion Nodal) method for hexagonal geometry. The results show that the HELIOSMASTER code system is fast and accurate enough to be used as nuclear core analysis tool for hexagonal geometry.ometry.

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DEVELOPMENT OF AN LES METHODOLOGY FOR COMPLEX GEOMETRIES

  • Merzari, Elia;Ninokata, Hisashi
    • Nuclear Engineering and Technology
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    • v.41 no.7
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    • pp.893-906
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    • 2009
  • The present work presents the development of a Large Eddy Simulation (LES) methodology viable for complex geometries and suitable for the simulation of rod-bundles. The use of LES and Direct Numerical Simulation (DNS) allows for a deeper analysis of the flow field and the use of stochastical tools in order to obtain additional insight into rod-bundle hydrodynamics. Moreover, traditional steady-state CFD simulations fail to accurately predict distributions of velocity and temperature in rod-bundles when the pitch (P) to diameter (D) ratio P/D is smaller than 1.1 for triangular lattices of cylindrical pins. This deficiency is considered to be due to the failure to predict large-scale coherent structures in the region of the gap. The main features of the code include multi-block capability and the use of the fractional step algorithm. As a Sub-Grid-Scale (SGS) model, a Dynamic Smagorinsky model has been used. The code has been tested on plane channel flow and the flow in annular ducts. The results are in excellent agreement with experiments and previous calculations.

Low-Temperature Sinterbility of Semiconducting $BaTiO_3$ Ceramics with $Pb_5Ge_3O_11$ Additives ($Pb_5Ge_3O_11$에 의한 반도성 $BaTiO_3$ 세라믹스의 저온소결성)

  • 윤상옥;정형진;윤기현
    • Journal of the Korean Ceramic Society
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    • v.28 no.5
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    • pp.359-364
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    • 1991
  • The effects of Pb5Ge3O11 on the sinterbility and lattice variation of the semiconducting 0.15 mol% Y2O3 doped BaTiO3 have been investigated as functions of additive contents (from 0.25 mol% to 2.5 mol%) and sintering temperatures (from 110$0^{\circ}C$ to 130$0^{\circ}C$). As the amount of Pb5Ge3O11 increases, the sinterbility of BaTiO3 increases abruptly at around 115$0^{\circ}C$. During the sintering, the most of Pb+2 ions in additives penetrate into BaTiO3 lattices and Ge+4 ions present at grain boundaries. Therefore the c lattice of the BaTiO3 increases largely and then the tetragonality increases due to the diffusion of the Pb+2 ions.

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