• Title/Summary/Keyword: structural reaction

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Estimation of various amounts of kaolinite on concrete alkali-silica reactions using different machine learning methods

  • Aflatoonian, Moein;Mirhosseini, Ramin Tabatabaei
    • Structural Engineering and Mechanics
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    • v.83 no.1
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    • pp.79-92
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    • 2022
  • In this paper, the impact of a vernacular pozzolanic kaolinite mine on concrete alkali-silica reaction and strength has been evaluated. For making the samples, kaolinite powder with various levels has been used in the quality specification test of aggregates based on the ASTM C1260 standard in order to investigate the effect of kaolinite particles on reducing the reaction of the mortar bars. The compressive strength, X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM) experiments have been performed on concrete specimens. The obtained results show that addition of kaolinite powder to concrete will cause a pozzolanic reaction and decrease the permeability of concrete samples comparing to the reference concrete specimen. Further, various machine learning methods have been used to predict ASR-induced expansion per different amounts of kaolinite. In the process of modeling methods, optimal method is considered to have the lowest mean square error (MSE) simultaneous to having the highest correlation coefficient (R). Therefore, to evaluate the efficiency of the proposed model, the results of the support vector machine (SVM) method were compared with the decision tree method, regression analysis and neural network algorithm. The results of comparison of forecasting tools showed that support vector machines have outperformed the results of other methods. Therefore, the support vector machine method can be mentioned as an effective approach to predict ASR-induced expansion.

Structural Determination of Oxidation Products of Flavonoids in Alcoholic Aqueous Solution with Reactive Oxygen Species

  • Hirose, Yuko;Kakita, Mitsuko;Washizu, Toshiyuki;Matsugo, Seiichi
    • Journal of Photoscience
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    • v.9 no.2
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    • pp.424-426
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    • 2002
  • Recently, much attention has been paid to the physiological functions of flavonoids associated with their antioxidant properties. However, there was a lack of information on the molecular mechanism at which flavonoids play the antioxidative role. We have already studied on the oxidation of quercetin with hydrogen peroxide and sodium hypochlorite in alcoholic aqueous solution and determined the oxidation products. Through the structural analysis of the oxidation products, it was clarified that the hydroxyl group at C-3 in the C ring plays the important role in the antioxidative action of quercetin. Successively, rutin and (+)-catechin were oxidized with sodium hypochlorite and their mono- and di-chlorinated derivatives were obtained. These facts indicate that these flavonoids can directly scavenge hypochlorous acid and the active site in this scavenging reaction is not the hydroxyl group at C-3.

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Development of pre-processor for Fire Dynamics Simulator(FDS) (화재 전산 해석을 위한 전처리 프로그램 개발)

  • Lee, Sung-Su;Lee, Dong-Hyun;Park, Su-Mi;Ku, Hye-Yun
    • Proceedings of the Korea Institute of Fire Science and Engineering Conference
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    • 2005.05a
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    • pp.87-93
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    • 2005
  • 본 연구는 NIST사에서 개발된 FDS를 기반으로한 GUI환경의 전처리 프로그램의 개발에 관한 것이다. 개발된 프로그램은 GUI환경에서 임의의 직육면체를 생성하고 편집할수 있으며 또한 국립지리원에서 보유중인 DXF의 수치지도를 이용하여 지형에 관련된 모델링을 가능 하도록 하였다. 복잡한 지형의 모델링기능과 GUI 환경에서의 편의성은 FDS의 활용도를 높여줄 것이며 이를 이용한 화재 모사는 화재 발생시 진압/대피의 효율을 높여 화재에 대한 피해를 줄일 수 있을 것으로 판단된다.

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A Large-scale Structural Mixing Model applied to Blowout of Turbulent Nonpremixed Jet Flames in a Cross air-flow

  • Lee, Kee-Man;Shin, Hyun-Dong
    • 한국연소학회:학술대회논문집
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    • 1997.06a
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    • pp.163-173
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    • 1997
  • This article presents an application of a large-scale structural mixing model (Broadwell et al. 1984) to the blowout of turbulent reacting jets discharging perpendicularly into an unconfined cross air-flow. In an analysis of a common stability curve, a plausible explanation can be made that the phenomenon of blowout is related only to the mixing time scale of the two flows. The most notable observation is that the blowout distance is traced at fixed positions at all times according to the velocity ratio R. Measurements of the lower blowout limits in the liftable flame agree qualitatively with the blowout parameter ${\varepsilon}$, proposed by Broadwell et al. Good agreement between the results calculated by a modified blowout parameter ${\varepsilon}^'$ and experimental results confirms the important effect of a large-scale structure in specifying the stabilization feature of blowouts.

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Three Common Subunits in the Editing Domains of Class Ia tRNA Synthetases.

  • Lee, Keun-Woo;Kwon, Yong-Jung;Briggs, James M.
    • Journal of Industrial Technology
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    • v.24 no.B
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    • pp.139-142
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    • 2004
  • To identify conserved structural or functional subunit(s) in the CP1 (editing) domains of class Ia tRNA synthetases, five available structures were compared and analyzed. Through sequence alignments of the CP1 domains, three conserved regions were found near the amino acid binding site in the editing domain. Structural overlapping of the three subunits clearly showed that there exist three common structural subunits in all of the five editing RS structures. The new alignment suggests a translocation movement of the CP1 domain caused by the binding with tRNA. Based on the experimental and modeling results, it is proposed that subunits 1 and 3 accommodate the incoming amino acid binding, while subunit 2 contributes to the interactions with the adenosine ring of the A76 to stabilize the overall tRNA binding.. Since these subunits are critical for the editing reaction, we expect that these key structures should be conserved through all class Ia editing RSs.

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Dynamic Modeling and Control of Flexible Space Structures

  • Chae, Jang-Soo;Park, Tae-Won
    • Journal of Mechanical Science and Technology
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    • v.17 no.12
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    • pp.1912-1921
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    • 2003
  • This paper presents a global mode modeling of space structures and a control scheme from the practical point of view. Since the size of the satellite has become bigger and the accuracy of attitude control more strictly required, it is necessary to consider the structural flexibility of the spacecraft. Although it is well known that the finite element (FE) model can accurately model the flexibility of the satellite, there are associated problems : FE model has the system matrix with high order and does not provide any physical insights, and is available only after all structural features have been decided. Therefore, it is almost impossible to design attitude and orbit controller using FE model unless the structural features are in place. In order to deal with this problem, the control design scheme with the global mode (GM) model is suggested. This paper describes a flexible structure modeling and three-axis controller design process and demonstrates the adequate performance of the design with respect to the maneuverability by applying it to a large flexible spacecraft model.

Evaluation of Structural Stability of JIB Crane for a Feed Vessel According to the Luffing Angle (러핑각도에 따른 선박용 지브크레인의 구조 안정성 평가)

  • Lee, M.J.;Han, D.S.;Han, G.J.
    • Journal of Power System Engineering
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    • v.12 no.6
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    • pp.24-28
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    • 2008
  • It expects demand of ships which equipped with JIB crane growth to continue. However, demand of JIB crane is increased, domestic shipment company imitated the design of Europe and Japan. And we need to develop the functional system of the JIB crane and modernize it. We need to find the optimum luffing angle for saving energy when JIB crane works. This study analyzed buckling load of JIB and reaction force of support point and stress of JIB according to the luffing angle through finite element analysis when JIB crane loads 40 ton weight. And this study considered the safety factor 1.8 of material. Every design condition was KS A1627 standard. This study used ANSYS 10.0.

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A Study on Docking Analysis for Conventional LNGC (Conventional LNGC의 도킹 해석에 관한 연구)

  • Choi, Joong-Hyo;Park, Jae-Hyung
    • Special Issue of the Society of Naval Architects of Korea
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    • 2008.09a
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    • pp.10-15
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    • 2008
  • The proper docking block arrangement, loading condition and structural reinforcement are required to ensure structural safety of ship, when she is in re-docking and launching for inspection or repair. The large reaction force due to narrow bottom tangent area, heavy weight and ballast loading are occurred at aft body and fore body of ship. Especially, in case of LNGC, the strength evaluation is necessary for cargo hold areas including mid-body because tank hydro test is performed in dry-dock. The analysis results and experiences to confirm structural safety for docking of conventional LNGC$(138K{\sim}151.7K)$ are introduced in this paper.

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Structural Analysis for Light Weight Design of Reduction Gear Box Case of High Speed Train (고속전철 감속기 케이스의 경량화 설계를 위한 구조해석)

  • 김완두;한승우;임영식;권오웅;박순원
    • Proceedings of the KSR Conference
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    • 1999.05a
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    • pp.116-123
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    • 1999
  • A case of the axle gear box which was one of tile power transmission components of high speed train was supported by the bearings installed in axle and the reaction arm connected in bogie frame. Structural analyses of this case were executed for investigation the application of aluminum for weight reduction. The evaluations of the material strength, the thermal strength and deformation, and the stability of natural vibration were carried out according to computer simulation. It was found out that the steel case was safe from the structural failure. For the aluminum case, there was no worry about the vibration resonance and the static failure, but some efforts to reduce tile deformation of the bearing mounting part.

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Propylene Hydrogenation over Cubic Pt Nanoparticles Deposited on Alumina

  • Yoo, Jung-Whan;Lee, Sung-Min;Kim, Hyung-Tae;El-Sayed, M.A.
    • Bulletin of the Korean Chemical Society
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    • v.25 no.6
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    • pp.843-846
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    • 2004
  • Pt nanoparticles loaded on alumina through an impregnation at room temperature was prepared using $K_2PtCl_4$ and acrylic acid as capping material. Transmission electron microscopy showed that the deposited Pt particles indicate ca. 80% cubic shapes with a narrow distribution of 8-10 nm in size. Propylene hydrogenation over the catalyst has been carried out to evaluate their catalytic performance by the values of activation energy. It is determined from the initial rate, reaction order, and rate constant and is found to be $9.7{\pm}0.5$ kcal/mol. This value has been discussed by comparing to those of encapsulated- and truncated octahedral Pt nanoparticles deposited on alumina, respectively, to study influence of the particle size and shape, and capping material used on the activation energy.