• Title/Summary/Keyword: metallic structure

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Analysis and Test of Hydrodynamic Ram in Welded Metallic Water Tanks

  • Kim, Jong Heon;Kim, Chun-Gon;Jun, Seungmoon
    • International Journal of Aeronautical and Space Sciences
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    • v.16 no.1
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    • pp.41-49
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    • 2015
  • Analysis and test of hydrodynamic ram in welded metallic tanks containing water were performed to investigate the phenomena and to understand the effects on the resulting structural behavior. Arbitrary Lagrange-Euler coupling method was used for the analysis of the fluid-structure interaction occurring in the hydrodynamic ram, where the projectile, tank, and water are exchanging load, momentum, and energy during the traveling of the projectile through the water of the tank. For a better representation of the physical phenomena, modeling of the welded edges is added to the analysis to simulate the earlier weld line fracture and its influence on the resulting hydrodynamic ram behavior. Corresponding hydrodynamic tests were performed in a modified gas gun facility, and the following panel-based examinations of various parameters, such as displacement, velocity, stress, and energy, as well as hydrodynamic ram pressure show that the analysis and test are well correlated, and thus the results of the study reasonably explain the characteristics of the hydrodynamic ram. The methodology and procedures of the present study are applicable to the hydrodynamic ram assessment of airframe survivability design concepts.

Source Localization Technique for Metallic Impact Source by Using Phase Delay between Different Type Sensors (다종 센서간 위상 차이를 이용한 충격 위치추정 기법)

  • Choi, Kyoung-Sik;Choi, Young-Chul;Park, Jin-Ho;Kim, Whan-Woo
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.18 no.11
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    • pp.1143-1149
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    • 2008
  • In a nuclear power plant, loose part monitoring and its diagnostic technique is one of the major issues for ensuring the structural integrity of the reactor system. Typically, accelerometers are mounted on the surface of a reactor vessel to localize impact location cavsed by the impact of metallic substances on the reactor system. However, in some cases, the number of the accelerometers is not enough to estimate the impact location precisely. In such a case, one of alternative plan is to utilize another type sensors that can measure the vibration of the reactor structure even though the measuring frequency ranges are different from each others. The AE sensors installed on the reactor structure can be utilized as additional sensors for loose part monitoring. In this paper, we proposed a new method to estimate impact location by using both accelerometer signal and AE signal, simultaneously. The feasibility of the proposed method is verified by an experiment. The experimental results demonstrate that we can enhance the reliability and precision of the loose part monitoring.

Electronic Structure and Half-Metallicity in the Zr2RuZ (Z = Ga, In, Tl, Ge, Sn, and Pb) Heusler Alloys

  • Eftekhari, A.;Ahmadian, F.
    • Journal of the Korean Physical Society
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    • v.73 no.9
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    • pp.1370-1376
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    • 2018
  • The electronic structures, magnetic properties and half-metallicity in Zr2RuZ (Z = Ga, In, Tl, Ge, Sn, and Pb) alloys with AlCu2Mn and CuHg2Ti-type structures were investigated using first-principles density functional theory (DFT) calculations. The calculations showed that Zr2RuIn, Zr2RuTl, Zr2RuSn, and Zr2RuPb compounds with CuHg2Ti-type structures were half-metallic ferromagnets with half-metallic band gaps of 0.18, 0.24, 0.22, and 0.27 eV, respectively. The half-metallicity originated from d-d and covalent hybridizations between the transition metals Zr and Ru. The total magnetic moments of the Zr2RuZ (Z = In, Tl, Sn, and Pb) compounds with CuHg2Ti-type structures were integer values of 1μB and 2μB, which is in agreement with Slater-Pauling rule (Mtot=Ztot18). Among these compounds, Zr2RuIn and Zr2RuTl were half-metals over relatively wide regions of the lattice constants, indicating that these two new Heusler alloys are ideal candidates for use in spintronic devices.

The Changing Structure of Demand-Supply for Mineral Resources in South Korea (국내(國內) 광물자원(鑛物資源)의 수요(需要)-공급(供給)의 구조변화(構造變化))

  • Oh, Mihn-Soo
    • Economic and Environmental Geology
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    • v.23 no.3
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    • pp.309-322
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    • 1990
  • The accelerated industrialization of Korean economy over the last couple of decades has brought an era of mass consumption of mineral commodities. This increased consumption has been satisfied mainly by imports from abroad. South Korea has about 50 useful mineral commodities for the mineral industry, among 330 kinds of minerals described. In 1988 the self-sufficiency ratio of domestic demand for 44 non-fuel(metallic and non-metallic) minerals as a whole was no more than 29 percent. The ratio for 26 non-metallic minerals was much higher, about 66 percent. On the other hand, the ratio for 18 metallic minerals was relatively very low, about 6.3 percent. The correlation between GNP and mineral consumption in South Korea shows well the slow down patterns during the last two decades.

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Synthesis and Evaluation of Variable Temperature-Electrical Resistance Materials Coated on Metallic Bipolar Plates (온도 의존성 가변 저항 발열체로 표면 처리된 금속 분리판 제조 및 평가)

  • Jung, Hye-Mi;Noh, Jung-Hun;Im, Se-Joon;Lee, Jong Hyun;Ahn, Byung Ki;Um, Sukkee
    • 한국신재생에너지학회:학술대회논문집
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    • 2010.11a
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    • pp.73.1-73.1
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    • 2010
  • For the successful cold starting of a fuel cell engine, either internal of external heat supply must be made to overcome the formation of ice from water below the freezing point of water. In the present study, switchable vanadium oxide compounds as variable temperature-electrical resistance materials onto the surface of flat metallic bipolar plates have been prepared by a dip-coating technique via an aqueous sol-gel method. Subsequently, the chemical composition and micro-structure of the polycrystalline solid thin films were analyzed by X-ray diffraction, X-ray fluorescence spectroscopy, and field emission scanning electron microscopy. In addition, it was carefully measured electrical resistance hysteresis loop over a temperature range from 20C to 80C using the four-point probe method. The experimental results revealed that the thin films was mainly composed of Karelianite V2O3 which acts as negative temperature coefficient materials. Also, it was found that thermal dissipation rate of the vanadium oxide thin films partially satisfy about 50% saving of the substantial amount of energy required for ice melting at 20C. Moreover, electrical resistances of the vanadium-based materials converge on an extremely small value similar to that of pure flat metallic bipolar plates at higher temperature, i.e. T40C. As a consequence, experimental studies proved that it is possible to apply the variable temperature-electrical resistance material based on vanadium oxides for the cold starting enhancement of a fuel cell vehicle and minimize parasitic power loss and eliminate any necessity for external equipment for heat supply in freezing conditions.

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Effect of CeO2 buffer layer on the crystallization of YBCO thin film on Hastelloy substrate (비정질 금속 기판상에 증착된 YBCO 박막의 결정성에 대한 CEO2 완충막의 효과)

  • Kim, Sung-Min;Lee, Sang-Yeol
    • 한국초전도학회:학술대회논문집
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    • v.9
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    • pp.392-396
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    • 1999
  • Superconducting YBa2Cu3O7δ(YBCO) thin films were grown on Hastelloy(Ni-Cr-Mo alloys) with CeO2 buffer layer in-situ by pulsed laser deposition in a multi-target processing chamber. To apply superconducting property on power transmission line, we have deposited YBCO thin film on flexible metallic substrate. However, it is difficult to grow the YBCO films on flexible metallic substrates due to both interdiffusion problem between metallic substrate and superconducting overlayers and non-crystallization of YBCO on amorphous substrate. It is necessary to use a buffer layer to overcome the difficulties. We have chosen CeO2 as a buffer layer which has cubic structure of 5.41 \AA lattice parameter and only 0.2% of lattice mismatch with 3.82 \AA of a-axis lattice parameter of YBCO on [110] direction of CeO2 In order to enhance the crystallization of YBCO films on metallic substrates, we deposited CeO2 buffer layers with varying temperature and 02 pressure. By XRD, it is observed that dominated film orientation is strongly depending on the deposition temperature of CeO2 layer. The dominated orientation of CeO2 buffer layer is changed from (200) to(111) by increasing the deposition temperature and this transition affects the crystallization of YBCO superconducting film on CeO2 buffered Hastelloy.

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The Mechanical Properties and Biocompatibility of Functionally Graded Coatings(FGC) of Hydroxyapatite(HA) and Metallic Powders - Functionally Gradient Coatings of Thermal Spray in Air- (Hydroxyapatite (HA)와 금속 분말 경사 코팅의 기계적 특성 및 생체 적합성 - 대기 열용사 경사코팅 -)

  • Kim, Eun-Hye;Kim, Yu-Chan;Han, Seung-hee;Yang, Seok-Jo;Park, Jin-Woo;Seok, Hyun-Kwang
    • Korean Journal of Metals and Materials
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    • v.47 no.1
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    • pp.13-20
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    • 2009
  • This work presents functionally graded coatings (FGC) of hydroxyapatite (HA) and metallic powders on Ti-6Al-4V implants using plasma spray coating method. HA has been the most frequently used coating material due to its excellent compatibility with human bones. However, because of the abrupt changes in thermomechanical properties between HA and the metallic implant across an interface, and residual stress induced on cooling from coating temperture to room temperature, debonding at the interface occurs in use sometimes. In this work, FGC of HA and Ti or Ti-alloy powders is made to mitigate the abrupt property changes at the interface and the effect of FGC on residual stress release is investigated by evaluating the mechanical bond strength between the implant and the HA coating layers. Thermal annealing is done after coating in order to crystallize the HA coating layer which tends to have amorphous structure during thermal spray coating. The effects of types and compositional ratio of metallic powders in FGC and annealing conditions on the bond strength are also evaluated by strength tests and the microstructure analysis of coating layers and interfaces. Finally, biocompatibility of the coating layers are tested under ISO 10993-5.

Geometric structure and electronic behavior of Rh decorating effect on zigzag CNTs (n=7-12): A DFT study

  • Cui, Hao;Zhang, Xiaoxing;Zhou, Yongjian;Zhang, Jun
    • Carbon letters
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    • v.26
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    • pp.61-65
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    • 2018
  • Comprehensive calculations of the Rh decoration effect on zigzag CNTs with n ranging from 7 to 12 were conducted in this work to understand the effect of Rh doping on geometric structures and electronic behaviors upon metallic and semiconducting CNTs. The obtained results indicated that Rh dopant not only contributes to the deformation of C-C bonds on the sidewall of CNTs, but also transforms the electron distribution of related complexes, thereby leading to a remarkable increase of the conductivity of pure CNTs given the emerged novel state within the energy gap for metallic CNTs and the narrowed energy gap for semiconducting CNTs. Our calculations will be meaningful for exploiting novel CNT-based materials with better sensitivity to electrons and higher electrical conductivity compared with pure CNTs.

Optimal Design of Metallic Sandwich Plates with Inner Dimpled Shell Subjected to 3-Point Bending (굽힘 하중을 받는 딤플형 금속 샌드위치판재의 최적설계)

  • Seong D.Y.;Jung C.G.;Yoon S.J.;Yang D.Y.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.702-705
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    • 2005
  • Metallic sandwich plates with Inner dimpled shell subjected to 3-point bending have been analyzed and then optimized for minimum weight. Inner dimpled shells can be easily fabricated by press or roll with high quality precision and bonded with same material skin sheets by resistance welding or adhesive bonding process. Optimized shape of inner dimple is a hemispherical shell to minimize weight without failure, including face yielding, face buckling and inner dimple buckling. It is demonstrated that bending stiffness of sandwich plate is 2 or 3 times than solid plates with same strength

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Development of Structural Analysis Modeling for KALIMER Fuel Rod

  • Kang, Hee-Young;Cheol Nam;Woan Hwang
    • Proceedings of the Korean Nuclear Society Conference
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    • 1998.05b
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    • pp.175-180
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    • 1998
  • The U-Zr metallic alloy with low swelling HT9 cladding is the candidate for the KALIMER fuel rod. The fuel rod should be able to maintain the structural integrity during its lifetime in the reactor. In a typical metallic fuel rod, load is mainly applied by internal gas pressure, and the deformation is primarily caused by creep of the cladding. The three-dimensional FEM modelling of a fuel rod is important to predict the structural behavior in concept design stage. Using the ANSYS code, the 3-D structure analyses were performed for various configuration, element and loads. It has been shown that the present analysis model properly evaluate the structural integrity of fuel rod. The present analysis results show that the fuel rod is expected to maintain its structural integrity during normal operation.

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