• Title/Summary/Keyword: Core Spectrum

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Study on Cognitive Engine Platform Based on the Spectrum Sharing for the Military Tactical Communications (군 전술 통신에서의 주파수 공동사용 기반 인지엔진 플랫폼 연구)

  • Choi, Joo-Pyoung;Lee, Won-Cheol
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.27 no.7
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    • pp.599-611
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    • 2016
  • This paper proposes a cognitive engine platform that enables dynamic spectrum access(DSA) based on a spectrum sharing system for the military tactical network environment. The current military tactical wireless communication system is increasing need to secure a supplementary wireless spectrum to ensure that multiple wireless networks for different weapon systems co-exist, so that tactical wireless communication between the same or different systems can be operated effectively. This paper examined policy development and research activities engaged by the U.S. and European countries on wireless spectrum sharing to secure more spectrum. It also introduces the current status of cognitive engine development, which is the core technology of tactical wireless communication for DSA. In addition, based on the investigation performed into the latest trends, we propose a platform structure for a cognitive engine based on a spectrum sharing method where more frequencies can be added for tactical radio communication, so that DSA can be realized, and wireless networks of different weapon systems can co-exist.

Optical properties of HgTe and HgTe/CdTe core-shell structured nanocrystals (HgTe와 HgTe/CdTe core-shell 구조의 나노입자의 광학적 특성 비교)

  • Park, Byoung-Jun;Kim, Hyun-Suk;Cho, Kyoung-Ah;Kim, Jin-Hyong;Lee, Joon-Woo;Kim, Sang-Sig
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.07a
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    • pp.56-59
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    • 2004
  • HgTe and HgTe/CdTe core-shell structured nanocrystals(NCs) were synthesized in aqueous solution by colloidal method. HgTe and HgTe/CdTe NCs structure showed very similar XRD patterns because of the same lattice constant and crystal structure of both samples. The absorption and photoluminescence(PL) spectrum of the synthesized HgTe NCs revealed the strong exitonic peak in the IR region. The PL spectrum of HgTe/CdTe NCs have the intense peak in about 700nm shorter than that of HgTe by 400nm. The photocurrent measurement of colloidal NCs are performed using He-Ne laser for light source. The photocurrent of HgTe NCs shows the instant increased current response to light, but HgTe/CdTe NCs revealed a decreased current when lighted to the sample. In the vacuum condition, it shows reverse result that current increased under the illumination of light and it is thought that the molecules like the hydro-oxygen gas in the air give an important effect on the current mechanism.

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Smart Honeycomb Sandwich Panels With Damage Detection and Shape Recovery Functions

  • Okabe, Yoji;Minakuchi, Shu;Shiraishi, Nobuo;Murakami, Ken;Takeda, Nobuo
    • Advanced Composite Materials
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    • v.17 no.1
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    • pp.41-56
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    • 2008
  • In this research, optical fiber sensors and shape memory alloys (SMA) were incorporated into sandwich panels for development of a smart honeycomb sandwich structure with damage detection and shape recovery functions. First, small-diameter fiber Bragg grating (FBG) sensors were embedded in the adhesive layer between a CFRP face-sheet and an aluminum honeycomb core. From the change in the reflection spectrum of the FBG sensors, the debonding between the face-sheet and the core and the deformation of the face-sheet due to impact loading could be well detected. Then, the authors developed the SMA honeycomb core and bonded CFRP face-sheets to the core. When an impact load was applied to the panel, the cell walls of the core were buckled and the face-sheet was bent. However, after the panel was heated over the reverse transformation finish temperature of the SMA, the core buckling disappeared and the deflection of the face-sheet was relieved. Hence the bending stiffness of the panel could be recovered.

Measurements of Thermal Neutron Spectrum Parameters in the TRIGA Mark II Reactor

  • Yang, Jae-Choon
    • Nuclear Engineering and Technology
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    • v.11 no.1
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    • pp.21-27
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    • 1979
  • The relative reaction rates were measured in the TRIGA Mark II reactor core and analyzed to obtain the neutron spectrum parameters; relative neutron temperature T$^{n}$ and epithermal index (equation omitted) Measurements were made with the central thimble and the F2 position containing the light water. The relative neutron temperature was represented by the activation ratio of Lu-Mn, and the epithermal index was measured by Au-Mn foil activation. The multichannel analyzer was used to measure the relative ${\gamma}$-rays of the detector foils. The results were compared with the calculated values.

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A Study on the Approach for Introducing Enterprise Content Management (전사 콘텐트 관리를 위한 접근방법 연구)

  • Koo, Heung-Seo
    • Journal of Korea Society of Industrial Information Systems
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    • v.12 no.5
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    • pp.47-53
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    • 2007
  • On account of supporting the full spectrum of content types in enterprises, customers recognize the problems of the conventional way, that is, point solutions for content management. And then they increase the requirement for ECM (Enterprise Content Management) solutions. In this paper, we survey the spectrum of enterprise content, the components, core value, the market landscape, and application cases of ECM, in order to suggesting the prospective customers the approach for enterprise-wide content management.

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Synaptic Plasticity in Mouse Models of Autism Spectrum Disorders

  • Chung, Leeyup;Bey, Alexandra L.;Jiang, Yong-Hui
    • The Korean Journal of Physiology and Pharmacology
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    • v.16 no.6
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    • pp.369-378
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    • 2012
  • Analysis of synaptic plasticity together with behavioral and molecular studies have become a popular approach to model autism spectrum disorders in order to gain insight into the pathosphysiological mechanisms and to find therapeutic targets. Abnormalities of specific types of synaptic plasticity have been revealed in numerous genetically modified mice that have molecular construct validity to human autism spectrum disorders. Constrained by the feasibility of technique, the common regions analyzed in most studies are hippocampus and visual cortex. The relevance of the synaptic defects in these regions to the behavioral abnormalities of autistic like behaviors is still a subject of debate. Because the exact regions or circuits responsible for the core features of autistic behaviors in humans are still poorly understood, investigation using region-specific conditional mutant mice may help to provide the insight into the neuroanatomical basis of autism in the future.

Investigation of Hydrodynamic Mass Characteristic for Flow Mixing Header Assembly in SMART (SMART 유동혼합헤더집합체의 동수력 질량 특성 고찰)

  • Lee, Gyu Mahn;Ahn, Kwanghyun;Lee, Kang-Heon;Lee, Jae Seon
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.16 no.1
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    • pp.30-36
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    • 2020
  • In SMART, the flow mixing header assembly (FMHA) is used to mix the coolant flowing into the reactor core to maintain a uniform temperature. The FMHA is designed to have enough stiffness so the resonance with reactor internal structures does not occurs during the pipe break and the seismic accidents. Since the gap between the FMHA and the core support barrel assembly is very narrow compared with the diameter of FMHA, the hydrodynamic mass effect acting on the FMHA is not negligible. Therefore the hydrodynamic mass characteristics on the FMHA are investigated to consider the fluid and structure interaction effects. The result of modal analysis for the dry and underwater conditions, the natural frequency of primary vibration mode for the horizontal direction is reduced from 136.67 Hz to 43.76 Hz. Also the result of frequency response spectrum seismic analysis for the dry and underwater conditions, the maximum equivalent stress are increased from 13.89 MPa to 40.23 MPa. Therefore, reactor internal structures located in underwater condition shall consider carefully the hydrodynamic mass effects even though they have sufficient stiffness required for performing its functions under the dry condition.

Comprehensive validation of silicon cross sections

  • Czakoj, Tomas;Kostal, Michal;Simon, Jan;Soltes, Jaroslav;Marecek, Martin;Capote, Roberto
    • Nuclear Engineering and Technology
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    • v.52 no.12
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    • pp.2717-2724
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    • 2020
  • Silicon, especially silicon in the form of SiO2, is a major component of rocks. Final spent fuel storages, which are being designed, are located in suitable rock formations in the Earth's crust. Reduction of the uncertainty of silicon neutron scattering and capture is needed; improved silicon evaluations have been recently produced by the ORNL/IAEA collaboration within the INDEN project. This paper deals with the nuclear data validation of that evaluation performed at the LR-0 reactor by means of critical experiments and measurement of reaction rates. Large amounts of silicon were used both as pure crystalline silicon and SiO2 sand. The critical moderator level was measured for various core configurations. Reaction rates were determined in the largest core configuration. Simulations of the experimental setup were performed using the MCNP6.2 code. The obtained results show the improvement in silicon cross-sections in the INDEN evaluations compared to existing evaluations in major libraries. The new Thermal Scattering Law for SiO2 published in ENDF/B-VIII.0 additionally reduces the discrepancy between calculation and experiments. However, an unphysical peak is visible in the neutron spectrum in SiO2 obtained by calculation with the new Thermal Scattering Law.

A Study of Flow Induced Noise for Multilayered Cylinder due to Turbulent Boundary Layer (난류경계층에 의한 다층재질 원통형 실린더의 유체소음 해석 연구)

  • 신구균;홍진숙;이헌곤
    • Journal of KSNVE
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    • v.6 no.5
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    • pp.671-677
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    • 1996
  • This paper presents the analytical method for predicting turbulence- induced noise in the multilayered cylinder composed of an outer hose, an inner fluid and an internal core. It is assumed that an infinite axisymmetric cylinder is located horizontally in water with free stream velocity and the turbulent boundary layer (TBL) surrounding the outer hose is fully developed and homogeneous. The transfer function at the core surface due to the propagation of the pressure fluctuation within the TBL is formulated using the linearized Navier-Stockes equation for solid and fluid. In the estimation of the energy spectrum of wall pressure fluctuation, the empirical formula proposed by Strawderman based on the Corcos model is used. A general algorithm for the calculation of the pressure level at the surface of a core, that is, turbulence- induced noise, is presented. Through the detailed numerical simulation, it is found that the major noise mechanism is the propagation of the bulge wave along hose.

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