• Title/Summary/Keyword: Metal core

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Mechanical Behavior of Sandwich Panels with Quasi-Kagome Truss Core Fabricated from Expanded Metals (확장금속망을 이용하여 제작된 준카고메 트러스 중간층을 갖는 샌드위치 판재의 기계적 거동)

  • Lim, Chae-Hong;Lim, Ji-Hyun;Jung, Jae-Gyu;Lim, Jong-Dae;Kang, Ki-Ju
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.30 no.9 s.252
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    • pp.1078-1085
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    • 2006
  • Many studies have been focused on how to manufacture ultra light metal structures and optimize them. In this study, we introduced a new idea to make sandwich panels with quasi-Kagome truss cores. First, metal sheets with a peculiar pattern of slits were expanded to be meshes, they are crimped into a triangular wave pattern, and then one third of struts were bent reversely to be quasi-Kagome trusses. Finally, two face sheets were bonded on the upper and the lower sides. The bending strength was estimated through elementary mechanics for the sandwich specimens with two kinds of face sheet the results of estimation were compared with the those of finite element analyses and experiments.

Development of the Micro Metal Balloon Using Sirasu-balloons as a Core Material

  • Uezono, Tsuyoshi;Sodeyama, Ken-ichi;Onomae, Hiroshi;Sakka, Yoshio
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09a
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    • pp.604-605
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    • 2006
  • Recently the Marangoni convention is supposed to be an important phenomenon that significantly affects the solidification. For understanding the Marangoni convection mechanism, visualizing the convention phenomenon of molten tin with ultrasonic has been conducted. This paper reports developing a tracer material of micro metal balloon that is used in the molten system. We have succeeded in coating the surface of Shirasu-ballons with nickel by plating process. The obtained metal balloon is spherical and some characterizations were conducted.

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Design of Network-based Automation System for Detecting Metallic Objects in Food and Livestock (식품 및 축산물 금속검출기를 위한 네트워크 기반 자동화 시스템 설계)

  • Hang-Seok Cho;Dongik Lee
    • IEMEK Journal of Embedded Systems and Applications
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    • v.18 no.3
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    • pp.109-116
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    • 2023
  • This paper presents a network-based automation system for the detection of metallic objects in food and livestock. A metal detector is a core equipment used for the inspection required by HACCP. Since the existing metal detectors are manufactured as a single-body equipment, it is difficult to take into account various user requirements for the system. In order to overcome the drawback, this study presents a network-based automation system for metal detector utilizing an industrial fieldbus and modular components. The proposed system can effectively consider the various customer requirements and control schemes. The proposed system can also achieve the improvement in speed and success rate of detecting metallic objects. The effectiveness of the proposed system is demonstrated through a various experiments.

THE FIT OF ZIRCONIA FORE FABRICATED WITH CAD/CAM SYSTEM (CAD/CAM system으로 제작한 zirconia core의 적합도)

  • Seong Ji-Yun;Jeon Young-Chan;Jeong Chang-Mo;Lim Jang-Seop
    • The Journal of Korean Academy of Prosthodontics
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    • v.42 no.5
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    • pp.489-500
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    • 2004
  • Statement of problem: The use of zirconia prostheses fabricated with CAD/CAM system is on an increasing trend in dentistry. However, evaluation of the fit related to internal relief and marginal reproducibility of zirconia has not been reported. Purpose : This study was to evaluate the fit related to internal relief and marginal reproducibility of zirconia core fabricated with CAD/CAM system. Materials and methods: The evaluation was based on 30 zirconia cores and 5 IPS-Empress2 cores. Zirconia cores were fabricated in different conditions of internal relief(0, 10, 20, 30, 40 and $50{\mu}m$), and IPS-Empress2 cores were fabricated in accordance with the manufacturer's instructions. Before cementation, the marginal discrepancies or cores were measured on metal die. And then, each core was cemented to stone die, embedded in an acrylic resin and sectioned in two planes(mesiodistally and labiopalatally). The internal gaps were measured at the margin and axial surface. Measurements for the marginal discrepancies, the internal marginal gaps and the internal axial gaps were performed under a measuring microscope(Compact measuring microscope STM5; Olympus, Japan) at a magnification of ${\times}100$. In addition, the marginal conagurations of metal die, zirconia core and IPS-Empress2 core were examined with SEM(S-2700, Hitachi, Japan). Results : Within the limits of this study the results were as follows. 1. Compared with IPS-Empress2 cores, the marginal discrepancies of zirconia cores had no significant differences. the internal marginal gaps were statistically smaller and the internal axial gaps were statistically larger in each condition of internal relief. 2. The marginal discrepancies and the internal marginal gaps of zirconia cores had no significant differences related to the conditions of internal relief(P>0.05). 3. The internal axial gaps of zirconia cores with $0{\sim}20{\mu}$m for internal relief were significantly larger than that with $50{\mu}m$ (P<(0.0001). 4. SEM micrographs showed favorable marginal reproducibility of zirconia core and smooth texture on the milling surface. Conclusion: The marginal discrepancy and the internal gaps of zirconia core were clinically acceptable and the milling surface was showed smooth texture. For fabrication of the durable esthetic restoration, further investigations on complex design of core, milling accuracy, compatability of enamel porcelain and porcelain firing seems to be needed.

Vertical Variation of Sediment Structure and Geochemical Characteristics of Core Sediment in Nakdong River Midstream (낙동강 중류의 주상퇴적물에서 나타나는 퇴적 구조와 지화학적 특성의 수직적 변화)

  • Kim, Shin;Lee, Kyu Yeol;Kim, Ju Eon;Lee, Kwon Chul;Ahn, Jung Min;Lee, Injung;Jung, Kang Young;Im, Tae Hyo
    • Journal of Korean Society on Water Environment
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    • v.31 no.3
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    • pp.304-312
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    • 2015
  • In this study, we tried to determine the vertical variation of sediment structure and geochemical characteristics, core sediment was collected in the Nakdong River midstream on August, 2014. Core sediment mainly composed of sand (51.48%) and silt (46.21%) and coarsing upward changed from sM to mS facies. IL and TOC were decreased from lower to upper layer. C/N ratio was lower than 10 so the organic matters were originated from underwater creatures and C/S ratio was decreased from lower to upper layer. Heavy metal (Al, Fe, Zn, Cr, Pb, Ni, Cu, Cd) content were decreased from lower to upper layer and seriously polluted condition is not. These results are thought to be due to the effect of natural and anthropogenic in the fluctuation of flow.

Synthesis and Oxidation Behavior of Pd-Ir@CeO2 Core-shell Nanoparticles for Hydrogen Gas Sensor

  • Gi-Seung Shin;Dong-Seog Kim;Tuong Van Tran;Geun-Jae Oh;Seok-Yong Hong;Ho-Geun Song;Yeon-Tae Yu
    • Journal of Sensor Science and Technology
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    • v.33 no.5
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    • pp.288-297
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    • 2024
  • Currently, numerous studies are being conducted on metal oxide semiconductor (MOS) gas sensors for hydrogen detection, using Palladium (Pd) and Pd-based alloy nanoparticles (NPs) owing to their hydrogen absorption ability. Furthermore, several studies have reported that Pd-Iridium (Ir) alloys possess high hydrogen absorption capabilities in their bulk state. However, Ir growth is limited to above 2 nm and it does not mix extensively with other metals. Furthermore, as the hydrogen absorption capacity decreases with the reduction in particle size, it is necessary to synthesize nanoparticles of an appropriate size. Therefore, the synthesis of Pd-Ir alloy NPs larger than 10 nm is challenging. In this study, we report the synthesis of Pd-Ir NPs with an average diameter of 19 nm using a hydrothermal technique for the first time and fabricated Pd-Ir alloy NPs through calcination at 500℃ in Ar and air. To confirm alloy formation and oxidation behavior, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were performed. In addition, we synthesized Pd-Ir@CeO2 core-shell nanoparticles (CSNPs) as hydrogen gas-sensing materials. The Pd-Ir core was partially oxidized during heat treatment at 500℃ in air, and Pd-Ir@CeO2 CSNPs were finally changed into Pd-Ir(alloy)/PdO-IrO2@CeO2 CSNPs, which exhibited higher sensitivity and selectivity toward H2 gas compared to totally oxidized PdO-IrO2@CeO2 CSNPs and pure CeO2 NPs. The enhanced gas-sensing performance was attributed to the hydrogen absorption effect of the Pd-Ir(alloy) NPs.

Analysis of Core-level Spectra of the $Li/Ge(111)-3\times1$ Surface ($Li/Ge(111)-3\times1$ 표면의 Core-level 스펙트럼에 대한 분석 연구)

  • Cho, Hye-Jin;Kim, Yeong-Hoon;Lee, Geun-Seop
    • Journal of the Korean Vacuum Society
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    • v.15 no.1
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    • pp.31-36
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    • 2006
  • By analyzing the Ge 34 core-level photoelectron spectrum, we studied the structure of the $Li/Ge(111)-3\times1$ surface. Two surface related components tying on either side of the main bulk peak were identified in the Ge 3d spectrum. The existence and the position of the two surface components in the core-level spectrum from $Li/Ge(111)-3\times1$ is similar to those of the $Li/Ge(111)-3\times1$, suggesting the similarities in structure of the two surfaces. The core-level photoelectron spectra of the Li-induced $Li/Ge(111)-3\times1$ surface are well consistent with the honeycomb-chain-channel model, which was proposed as the structure of the $Si/Ge(111)-3\times1$ induced by alkali metals.

Effects and Application Cases of Injection Molds by using DED type Additive Manufacturing Process (DED방식의 적층가공을 통한 금형으로의 응용사례 및 효과)

  • Kim, Woosung;Hong, Myungpyo;Kim, Yanggon;Suh, Chang Hee;Lee, Jongwon;Lee, Sunghee;Sung, Ji Hyun
    • Journal of Welding and Joining
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    • v.32 no.4
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    • pp.10-14
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    • 2014
  • Laser aided Direct Metal Tooling(DMT) process is a kind of Additive Manufacturing processes (or 3D-Printing processes), which is developed for using various commercial steel powders such as P20, P21, SUS420, H13, D2 and other non-ferrous metal powders, aluminum alloys, titanium alloys, copper alloys and so on. The DMT process is a versatile process which can be applied to various fields like the mold industry, the medical industry, and the defense industry. Among of them, the application of DMT process to the mold industry is one of the most attractive and practical applications since the conformal cooling channel core of injection molds can be fabricated at the slightly expensive cost by using the hybrid fabrication method of DMT technology compared to the part fabricated with the machining technology. The main objectives of this study are to provide various characteristics of the parts made by DMT process compared to the same parts machined from bulk materials and prove the performance of the injection mold equipped with the conformal cooling channel core which is fabricated by the hybrid method of DMT process.

Characteristics of Embedded R, L, C Fabricated by Using LTCC-M Technology and Development of a PAM for LMR thereby (LTCC-M 기술을 이용한 내부실장 R, L, C 수동소자의 특징 및 LMR용 PAM개발)

  • 김인태;박성대;강현규;공선식;박윤휘;문제도
    • Journal of the Microelectronics and Packaging Society
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    • v.7 no.1
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    • pp.13-18
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    • 2000
  • Low temperature co-fired ceramics on metal (LTCC-M) is efficient for embedding passive components with good tolerance in a module due to the dimensional stability in x and y directions by the constraint of metal core during the firing. In addition, the radiation noise can be reduced by metal core. In this paper, embedded passive components were introduced and a power amplifier module (PAM) fabricated by using the passive components was explained. The embedded passive components in test patters showed the tolerance of 10~20% and the good repeatability in tolerance of embedded passives was maintained in module fabrication. The shortened traces in multi chip modules (MCMs) make the signal delay time decreased and the embedded passives simplify the packaging processes owing to the less solder points, which enhance the electrical performance and increase the reliability of the modules. The LTCC-M technology is one of the promising candidates for RF application and is expected to expand its applications to power and high performance devices.

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Numerical Modeling on Microsegregation with Tip-undercooling in Weld Metal of Binary Alloys (과냉을 고려한 2원계합금 용접용융부의 미시편적 거동에 대한 수치해석 모델링)

  • 박종민;박준민;이창희
    • Journal of Welding and Joining
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    • v.17 no.4
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    • pp.60-68
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    • 1999
  • The previously developed two dimensional model was modified in order to predict more accurately the degree of microsegregation and eutectic fraction on in weld metal whose solidification rate is very fast. The model employed the same assumptions with previous model but considered of a tip undercooling. The previously predicted microsegregation and eutectic fraction has the discrepancies between simulated and examined results in the weld metal solidification. The experiments for the weld metal solidification of 2024 A1 and Fe-Ni alloy were carried out in order to examine the reasonability and feasibility of this modified model. The concentration profile of the solute and eutectic fraction predicted by the simulation agreed well with those found from experimental works. According to the results, it was believed that the dendrite tip undercooling considered in the modified model be reasonable for predicting the degree of microsegregation more accurately in weld metla solidification. In the GTA welds, degree of dendrite-tip undercooling increases with increasing solidification rage(welding speed). This serves to increase the concentration of dendrite core and thus result in reducing the degree of segregation. And solid state diffusion(back diffusion) during solidification is very low in the weld metal solidification so that little additional homogenization of solute occurs during solidification. With consideration of tip undercooling this modified model can predict exactly degree of microsegregation and eutectic fraction from slow solidification(casting) to fast solidification(welding).

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