• Title, Summary, Keyword: Metallic

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REMARKS ON METALLIC MAPS BETWEEN METALLIC RIEMANNIAN MANIFOLDS AND CONSTANCY OF CERTAIN MAPS

  • Akyol, Mehmet Akif
    • Honam Mathematical Journal
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    • v.41 no.2
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    • pp.343-356
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    • 2019
  • In this paper, we introduce metallic maps between metallic Riemannian manifolds, provide an example and obtain certain conditions for such maps to be totally geodesic. We also give a sufficient condition for a map between metallic Riemannian manifolds to be harmonic map. Then we investigate the constancy of certain maps between metallic Riemannian manifolds and various manifolds by imposing the holomorphic-like condition. Moreover, we check the reverse case and show that some such maps are constant if there is a condition for this.

Fabrication of Bulk Metallic Glass Composites by Mechanical Milling with Subsequent Spark Plasma Sintering Process (기계적 밀링 및 방전 플라즈마 소결 공정을 이용한 벌크 비정질 복합재의 제조)

  • Lee, Jin-Kyu;Kim, Taek-Soo;Kim, Jeong-Gon
    • Journal of Korean Powder Metallurgy Institute
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    • v.14 no.3
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    • pp.197-201
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    • 2007
  • Bulk metallic glass (BMG) composite was fabricated by consolidation of milled metallic glass composite powders. The metallic glass composite powder was synthesized by a controlled milling process using the Cu-based metallic glass powder blended with 30 vol% Zr-based metallic glass powders. The milled composite powders showed a layered structure with three metallic phases, which is formed as a result of mechanical milling. By spark plasma sintering of milled metallic glass powders in the supercooled liquid region, a fully dense BMG composite was successfully synthesized.

Fabrication of Metallic Glass/metallic Glass Composites by Spark Plasma Sintering (방전플라즈마 소결법에 의한 비정질/비정질 복합재의 제조)

  • Lee, Jin-Kyu
    • Journal of Korean Powder Metallurgy Institute
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    • v.14 no.6
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    • pp.405-409
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    • 2007
  • The Cu-based bulk metallic glass (BMG) composites containing Zr-based metallic glass phase have been consolidated by spark plasma sintering using the mixture of Cu-based and Zr-based metallic glass powders in their overlapped supercooled liquid region. The Zr-based metallic glass phases are well distributed homogeneously in the Cu-based metallic glass matrix after consolidation process. The successful consolidation of BMG composites with dual amorphous phases was corresponding to the sound viscous flow of the two kinds of metallic glass powders in their overlapped supercooled liquid region.

A methodology for design of metallic dampers in retrofit of earthquake-damaged frame

  • Zhang, Chao;Zhou, Yun;Weng, Da G.;Lu, De H.;Wu, Cong X.
    • Structural Engineering and Mechanics
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    • v.56 no.4
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    • pp.569-588
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    • 2015
  • A comprehensive methodology is proposed for design of metallic dampers in seismic retrofit of earthquake-damaged frame structures. It is assumed that the metallic dampers remain elastic and only provide stiffness during frequent earthquake (i.e., earthquake with a 63% probability of exceedance in 50-year service period), while in precautionary earthquake (i.e., earthquake with a 10% probability of exceedance in 50-year service period), the metallic dampers yield before the main frame and dissipate most of the seismic energy to either prevent or minimize structural damages. Therefore by converting multi-story frame to an equivalent single-degree-of-freedom system, the added stiffness provided by metallic dampers is designed to control elastic story drifts within code-based demand under frequent earthquake, and the added damping with the combination of added stiffness influences is obtained to control structural stress within performance-based target under precautionary earthquake. With the equivalent added damping ratio, the expected damping forces provided by metallic dampers can be calculated to carry out the configuration and design of metallic dampers along with supporting braces. Based on a detailed example for retrofit of an earthquake-damaged reinforced concrete frame by using metallic dampers, the proposed design procedure is demonstrated to be simple and practical, which can not only meet current China's design codes but also be used in retrofit design of earthquake-damaged frame with metallic damper for reaching desirable performance objective.

Long Range UHF RFID Tag with a Rectangular Metallic Cavity Structure

  • Yeo, Jun-Ho
    • Journal of electromagnetic engineering and science
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    • v.10 no.3
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    • pp.121-126
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    • 2010
  • A long range UHF RFID tag with a rectangular metallic cavity structure is proposed for various applications with metallic objects. The proposed tag consists of a rectangular metallic cavity structure and a folded dipole antenna which is located on top of the cavity. The tag is designed for Korean UHF RFID band(910~914 MHz) and the bandwidth, which satisfies the -10 dB input reflection coefficient requirement, is approximately 1.3 %(904~916 MHz). Measurement demonstrates that the proposed tag shows long reading range up to 15 m when it is placed on a metallic plate.

Imperfection Mode of Thin Metallic Sandwich Plate with Pyramidal Metallic Inner Structures (피라미드형 금속 내부구조체를 가진 얇은 금속샌드위치 판재의 결함 모드)

  • Ahn, Dong-Gyu;Sun, Hyang-Sun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.37 no.2
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    • pp.187-192
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    • 2013
  • Thin metallic sandwich plate with pyramidal metallic inner structures is manufactured from a continuous projection welding between face sheets and inner structures. Due to the welding pressure, imperfections of inner structures induced by the deformation of the inner structures occur. The imperfections affect the response of the thin metallic sandwich plate subjected to low-velocity impact loading. The goal of this paper is to obtain a proper dominant imperfection mode of the thin metallic sandwich plate with pyramidal metallic inner structures. The variation of impact responses of the thin metallic sandwich plate for different imperfection modes are investigated by finite element analysis. The results of the FE analysis are compared to those of drop impact experiments. From the results of the comparison, it has been shown that the dominant imperfection mode of the thin metallic sandwich plate with pyramidal metallic inner structures is all type of symmetric imperfection mode with symmetrical imperfections of four struts.

An Experimental Approach for Modeling the Appearance of Metallic Painted Surfaces (메탈릭 페인트로 코팅된 재질의 모델링 방법에 관한 연구)

  • Chowdhury, Mijanur Rahaman;Kim, Kang-Yeon;Yoo, Hyun-Jin;Ko, Kwang-Hee;Lee, Kwan-H.
    • 한국HCI학회:학술대회논문집
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    • pp.1037-1044
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    • 2007
  • Metallic paint is one of the most widely used coating in automotive, cosmetic and other applications because of its well-known ability to give a product realistic look which creates widespread consumer appeal. But, this coating has complicated subsurface structure which includes pigments, flakes, and transparent clearcoat. Though various analytic reflection models are available to simulate appearance of various surfaces, it is difficult to select an appropriate reflection model with faithful parameters for simulating this coating due to the complex subsurface structure of metallic paints. This paper presents a framework for accurate modeling of metallic coating by determining an appropriate reflection model among various existing BRDF (Bidirectional Reflectance Distribution Function) models. The selection of the appropriate model is achieved by measuring BRDF of various metallic paint samples using a BRDF measuring device i.e. gonioreflectometer and fitting an existing model to the measured data. Then, this model is effectively realized by rendering metallic painted surfaces. We believe that this framework can serve as a guide for those who wants to render metallic painted surfaces accurately with analytic BRDF model without expending time on extracting BRDF data using gonioreflectometer from real metallic paint sample.

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Improvement of Metallic Micro-Structure Precision Employing Two-photon Induced Photoreduction Process (이광자 흡수 광환원 공정을 이용한 마이크로 금속형상 제작의 정밀화에 관한 연구)

  • Son, Yong;Lim, Tae-Woo;Yang, Dong-Yol;Prem, Prabhakaran;Lee, Kwang-Sup
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.32 no.9
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    • pp.754-760
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    • 2008
  • A two-photon induced photoreduction process suggests a possibility for fabricating complicated metallic microstructures which can be applied to 3-D micro-circuits and optical devices, etc. The process employs the photoreduction of silver ions in a metallic solution which is composed of metallic salt ($AgNO_3$) and watersoluble polymer ((poly(4-styrenesulfonique acid) 18wt. % in $H_2O$, $(C_8H_8O_3S)_n$)). In this process, the improvement of the resolution and the uniformity of fabricated metallic structures are important issues. To address these problems, continuous forming window (CFW) is obtained from a parametric study on the conditions of laser power and scanning velocity and the direct seed generation (DSG) method is proposed. Silver nano particles are uniformly generated in a metallic solution through the DSG method, which enables the decrease of a laser power to trigger the photoreduction of silver ions as well as the increase of metal contents in a metallic solution. So the two-photon induced photoreduction property of a metallic solution is improved. Through this work, precise silver patterns are fabricated with a minimum line width of 400 nm.

Consolidation of Bulk Metallic Glass Composites

  • Lee, Jin-Kyu;Kim, Hwi-Jun;Kim, Taek-Soo;Shin, Seung-Yong;Bae, Jung-Chan
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • pp.848-849
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    • 2006
  • Bulk metallic glass (BMG) composites combining a $Cu_{54}Ni_6Zr_{22}Ti_{18}$ matrix with brass powders or $Zr_{62}A_{l8}Ni_{13}Cu_{17}$ metallic glass powders were fabricated by spark plasma sintering. The brass powders and Zr-based metallic glass powders added for the enhancement of plasticity are well distributed homogeneously in the Cu-based metallic glass matrix after consolidation. The BMG composites show macroscopic plasticity after yielding, and the plastic strain increased to around 2% without a decrease in strength for the composite material containing 20 vol% Zr-based amorphous powders. The proper combination of strength and plasticity in the BMG composites was obtained by introducing a second phase in the metallic glass matrix.

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