• Title/Summary/Keyword: Metal spike

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Development of Tapered Rolling Type Strip Pressure Key for the Prevention of Scratch (스크래치 방지를 위한 테이퍼 롤링형 판재 누름키의 개발)

  • Kim, Tae-Wan
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.11 no.12
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    • pp.4715-4720
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    • 2010
  • In this study, we developed new tapered rolling type strip pressure key for the prevention of scratch in sheet metal forming line. The developed pressure key is equipped with two tapered rollers inside a conventional block pressure key. Through the scratch test, for the case of transversal movement the tapered rolling type pressure key reduces both friction and depth of scratch by the effect of tapered shape which decreases the pressure spike on edge, and for longitudinal movement the scratch on the sheet metal surface is certainly removed by the rolling contact.

The Characteristics of EBW for strengthened austenitic stainless steel (강화 오스테나이트 스테인레스강의 전자빔 용접 특성)

  • 정원희;김용재;정인철
    • Proceedings of the KWS Conference
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    • 2003.05a
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    • pp.87-89
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    • 2003
  • The yield strengths of austenitic stainless steel have been approximately doubled by increasing the nitrogen content. But, the increasing the nitrogen cause of increase the pressure of metal vapor inside the keyhole in electron beam welding. During welding, eruptions of keyhole often occur that cause excessive spatter, concavity, and porocity in the weld zone. Additionally the fast evaporation of nitrogen content cause of decrease the strength of weld zone. Therefore in this paper, we investigated of the weldability of electron beam welding and the change of chemical content after welding for strengthened austenitic stainless steel, measured the deformation scale of both of electron beam and narrow gap TIG and the spike fluctuation in the root.

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Sample Pretreatment for the Determination of Metal Impurities in Silicon Wafer (실리콘 웨이퍼 중의 금속 불순물 분석을 위한 시료 전처리)

  • Chung, H.Y.;Kim, Y. H.;Yoo, H.D.;Lee, S.H.
    • Journal of the Korean Chemical Society
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    • v.43 no.4
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    • pp.412-417
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    • 1999
  • The analytical results obtained by microwave digestion and acid digestion methods for sample pretreatment to determine metal impurities in silicon wafer by inductively coupled plasma-mass spectrometry (ICP-MS) were compared. In order to decompose the silicon wafer, a mixed solution of $HNO_3$ and HF was added to the sample and the metal elements were determined after removing the silicon matrix by evaporating silicon in the form of Si-F. The recovery percentages of Ni,Cr and Fe were found to be 95∼106% for both microwave digestion and acid digestion methods. The recovery percentage of Cu obtained by the acid digestion method was higher than that obtained by the microwave digestion method. For Zn, however, the microwave digestion method gave better result than the acid digestion method. Fe was added to a silicon wafer using a spin coater. The concentration of Fe in this sample was determined by lCP-MS, and the same results were obtained in the two pretreatment methods.

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A Study on Changes of Furniture Hard Ware in Korea - From the Joseon Era to Modern Times - (한국 가구 하드웨어 변화 연구 - 조선시대부터 현대까지 -)

  • Cho, Sook-Kyung;Moon, Sun-Ok
    • Journal of the Korea Furniture Society
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    • v.23 no.2
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    • pp.122-129
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    • 2012
  • This article was intended as fundamental materials to recognize the current status of furniture hard ware in Korean market and to fix the identity of Korean furniture, by investigating and comparing the furniture hard ware used in the Joseon era and in modern times by type, function, shape and material. The analysis of furniture hard ware of the Joseon era and modern times from the view of functional aspects was oriented to the hard ware necessary to open and close the door & drawer on one side, and to that being attached to the main body of furniture not to scratch the wood by another wood on the other side, and from this the following conclusion was drawn. First of all, "Gwangdoojung" - a kind of spike- and metal decoration on the edge of the furniture disappeared, while the function-oriented hard wares have been diversified in modern times, from the perspective of the change of kinds. Second, the functional aspect of the furniture hard ware was emphasized in modern times than the Joseon era. In other words, the hard wares of the Joseon era came into view due to their strong appeal to decoration, whereas those of modern times were mostly hidden or moderated, keeping the function substantially. Third, the hard wares from the Joseon era were shown in concrete and detailed shape motivated by natural objects and furthermore even gloriously, but the modern hard wares are simple & basic geometry, from a formative point of view. Fourth, the material aspects present that the Joseon era's hard ware was mainly cast iron, whereas that of modern times shows the diversification from metal to even plastic. Finally, the recent trend in naming of the hard wares is the words of foreign origin. This resulted from that the foreign names of hard wares are valid also after import process in Korean market, so the domestic development of hard ware as the essential factor for the furniture design is urgently necessary to establish the identity of Korean modern furniture.

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Determination of Metal Impurities at Near Surface of Silicon Wafer by Etching Method (에칭법을 이용한 실리콘 웨이퍼 표면 근처에서의 금속 분순물의 정량)

  • Kim, Young-Hoon;Chung, Hye-Young;Cho, Hyo-Yong;Lee, Bo-Young;Yoo, Hak-Do
    • Journal of the Korean Chemical Society
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    • v.44 no.3
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    • pp.200-206
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    • 2000
  • The metal impurities in specific regions at near surface of silicon wafer were determined by constant depth etching·lt is possible to etch uniformly over the entire wafer surface by 1$\mu\textrm{m}$ depth with 5 mL of etching solution made up of HF and HNO$_3$ mixed by l:3 volume ratio. The microwave oven was used to evaporate the solution after etching. After spiking, The recoveries of Cu, Ni, Zn, Cr, Mg and K were found to be 99∼105%ted in polysilicon region and could be quantified by 1$\mu\textrm{m}$ depth.

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EVALUATION OF NOx REDUCTION CATALYST BY MODEL GAS FOR LEAN-BURN NATURAL GAS ENGINE

  • LEE C. H.;CHO B. C.
    • International Journal of Automotive Technology
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    • v.6 no.6
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    • pp.591-598
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    • 2005
  • A three-way catalyst system of a natural gas vehicle (NGV) has characteristics of higher fuel consumption and higher thermal load than a lean-bum catalyst system. To meet stringent emission standards in the future, NGV with the lean-bum engine may need a catalyst system to reduce the amounts of HC, CO and NOx emission, although natural gas system has low emission characteristics. We conducted experiments to evaluate the conversion efficiency of the NOx reduction catalyst for the lean-burn natural gas engine. The NOx reduction catalysts were prepared with the ${\gamma}-Al_{2}O_3$ washcoat including Ba based on Pt, Pd and Rh precious metal. In the experiments, effective parameters were space velocity, spike duration of the rich condition, and the temperature of flowing model gas. From the results of the experiments, we found that the temperature for maximum NOx reduction was around $450^{\circ}C$, and the space velocity for optimum NOx reduction was around $30,000\;h^{-1}$ And we developed an evaluation model of the NOx reduction catalyst to evaluate the conversion performance of each other catalysts.

Finite Element Analysis of Two-Dimensional Cold Forging By Using Modular Remeshing and Expert System (단위체 격자 재구성법과 전문가 시스템을 이용한 2차원 냉간 단조의 유한 요소 해석)

  • Yun, Hui-Do;Kim, Yeong-Tae;Lee, Nak-Gyu;Yang, Dong-Yeol;Lee, Byeong-Chae
    • Journal of the Korean Society for Precision Engineering
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    • v.9 no.3
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    • pp.83-101
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    • 1992
  • A systematic method of remeshing is required due to severe mesh distortion after some finite deformation in the finite element analysis of practical forging processes. In order to cope with the problem of mesh degeneracy during deformation, the proper design of meshes plays an improtant role in the analysis. In so-called "Modular Remeshing", the physical characteristics of metal flow and geometric characteristics are incorporated in "Module", which can be applied to the mesh design for a certain mode of deformation in so far as the topology of deforming region remains the same. For the purpose of more effective and systematic use of the modular remeshing scheme, an expert system has been developed in the framework of the proposed remeshing schemel. In oredr to show the effectiveness of the method, the rib-web type forging with axial relief or radial relief and spike forging are simulated. It has been thus shown that the proposed method of automatic remeshing by using modular remeshing and expert system can be futher extended and applied to various forging problems with complicated geometrical configurations.ical configurations.

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Hourglass Control in Rigid-Plastic Finite Element Analysis (강소성 유한요소해석에서 Hourglass Control)

  • Gang, Jeong-Jin;O, Su-Ik
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.20 no.4
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    • pp.1290-1300
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    • 1996
  • The finite element method, based on rigid-plastic formulation, is widely used to simulate metal forming processes. In order to improve the computational efficiency of the rigid-plastic FEM, one-point integration is used to evaluate the stiffness matrix with four-node rectangular elements and eight-node brick elements. In order to control the hourglass modes, hourglass strain rate components were introduced and included in the effective strain rate definition, Numerical tests have shown that the proposed one-point integration scheme reduces the stiffness matrix evaluation time without deteriorating the convergence behavior of Newton-Raphson method. Simulations of a ring compression, a plane-strain closed-die forging and the three-dimensional spike forging processes were carried out by using the proposed integration method. The simulation results are compared to those obtained by applying the conventional integraiton method in terms of the solution accuracy and computational efficiency.

Evaluation on usefulness of three dimensional reconstructive computed tomography images after pedicle screws fixation (척추경 나사못 고정술 시행 후 3차원 재구성CT영상의 유용성 평가)

  • Kim, Hyeon-Ju;Jang, Hyun-Chul;Cho, Jae-Hwan
    • Journal of Digital Contents Society
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    • v.11 no.4
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    • pp.553-559
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    • 2010
  • By applying the various reformation techniques by using a circle raw data of after computed tomography image in the patient enforcing the spine screw fixation, this research tried to look into the various information including the exact location of the position of the screw spike and accuracy of an operation. In a clinical, by applying the or multi planar reformatting(MPR), that is the re-composition technique used mainly, maximum intensity projection (MIP), and volume rendering technique(VRT) and transformation removal from a register modifying VRT, video data were compared and were analyzed by the quantitative method and qualitative method. It is judged as the transformation volume rendering technique of the re-composition technique which is most useful in minimizing the artifact shadow by the exact location of the position of a screw and metal among the analysis and evaluation result computed tomography image reformation technique of the reformation image after the spine screw fixation.

Measurements of Fast Transient Voltages due to Human Electrostatic Discharges (인체에 대전된 정전기 방전에 의해 발생한 급속과도전압의 측정)

  • 이복희;이동문;강성만;엄주홍;이태룡;이승칠
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.16 no.4
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    • pp.108-116
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    • 2002
  • This paper presents the measurements and evaluation of voltage waveforms due to human electrostatic discharge(ESD). The principle of operation and design rule of a new device for measuring the ESD fast transient voltages with very fast rise time were described. Peak values and rise time of ESD voltages derived from a charged human body under a variety of experimental conditions were examined. The frequency bandwidth of the proposed voltage measuring system ranges from DC to 400[㎒]. The ESD voltage waveform is nearly equal to the ESD current waveform and the peak amplitude of ESD current waveform is roughly proportional to the ESD voltage in each experimental conditions. A rapid approach results in a discharge voltage with a faster initial rise time than for a slow approach. The voltages caused by direct finger ESDs have an initial slope with a relatively long, 10∼30[ns] rise time, but the amplitude is small. On the other hand, the voltages caused by direct hand/metal ESDs have a steep initial s1ope with 1 ∼3[ns] rise time, but an initial spike is very big. As a consequence, it was found that the ESD voltage and current waveforms strongly depend on the approach speed and material of intruder. These measurement results would be useful to design the ESD protective devices.