• Title/Summary/Keyword: Metallic element

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Optimization of Peltier Current Leads Cooled by Two-Stage Refrigerators

  • Jeong, Eun-Soo
    • International Journal of Air-Conditioning and Refrigeration
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    • v.14 no.3
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    • pp.94-101
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    • 2006
  • A theoretical investigation to find thermodynamically optimum design conditions of conduction-cooled Peltier current leads is performed. A Peltier current lead (PCL) is composed of a thermoelectric element (TE), a metallic lead and a high temperature superconductor (HTS) lead in the order of decreasing temperature. Mathematical expressions for the minimum heat flow per unit current crossing the TE-metal interface and the minimum heat flow per unit current from the metal lead to the joint of the metal and the HTS leads are obtained. It is shown that the temperature at the TE -metal interface possesses a unique optimal value that minimizes the heat flow to the joint and that this optimal value depends on the material properties of the TE and the metallic lead but not the joint temperature nor electric current. It is also shown that there exists a unique optimal value for the joint temperature between the metal and the HTS leads that minimizes the sum of the power dissipated by ohmic heating in the current leads and the refrigerator power consumed to cool the lead, for a given length of the HTS.

An Analysis Finite Element for Elasto-Plastic Stresses Considerating Phase Transformation at the Quenching Process(I) - From Austenite to Pearlite - (퀜칭과정에서 상변태를 고려한 탄소성 열응력의 유한요소해석(I) -오스테나이트에서 퍼얼라이트로의 변태-)

  • Kim, Ok-Sam;Koo, Bon-Kwon
    • Journal of the Korean Society for Heat Treatment
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    • v.7 no.4
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    • pp.233-243
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    • 1994
  • Constitutive relation of thermoelasto-plastic material undergoing phase transformation during quenching process were developed on the basic of continuum thermodynamics. The metallic structure, temperature and residual stresses distributions were numerically calculated by the finite element technique. The metallic structure were defined by transformation from austenite to pearlite and characterized as a fuction of thermal history and mixture rule of phase. On the distribution of thermal stress along the radial direction, axial and tangential stresses are compressive in the surface, and tential in the inner part. Radial stress is tensile in the whole body. The reversion of residual stress takes plase at 11.5~15.5mm from the center.

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FEM Analysis of Turning Multi-layer Metal (다중 적층 금속의 선삭가공에 대한 FEM 해석)

  • Kim, Key-Sun
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.10 no.4
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    • pp.57-63
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    • 2011
  • The aim of this study is to analyze turning process using commercial FEM simulation code. Various simulation models of orthogonal cutting process for 3 layers of metallic material have been simulated and analyzed. The workpiece material used for the orthogonal plane-strain metal cutting simulation consists of three layers, which are Allow Tool Steel, Aluminum and Stainless Steel. The finite element model is composed of a deformable workpiece and a rigid tool. The tool penetrates through the workpiece at a constant speed and constant feed rate. As an analytical result, detailed cutting temperature, strain, pressure, residual stress for both a tool and each layer of workpiece were obtained during the turning process. It has been closely observed that the chip flow curve deforms continuously.

A Study on the Contact Stress Analysis of the Coating Layer Using Finite Element Method (유한요소법을 이용한 Coating Layer의 접촉응력 해석에 관한 연구)

  • 김청균;오병택
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 1996.10a
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    • pp.183-188
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    • 1996
  • Films and coatings are used for an enormous and diverse set of applications including mechanical, electronic and optical devices, protection at high temperature, cutting tools enhancement and automotive use. Many of these applications require the various properties associated with inorganic and metallic / non-metallic materials; i.e., with ceramics. Therefore, a large number of coatings have been developed and used for a long time in the various fields, especially in mechanical one. As one of the mutual surface actions, the problems of contact stresses are complex. The relationship between load and stress are nonlinear. Besides, the material is often apt to deform plastically under low load. However, analytical solutions exist only for some simple problems. If a material has a complicated shape or inhomogeneous properties, numerical method must be used. In this paper, the analysis of the contact stress of the coating layer was solved, using the finite element method.

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Finite Element Analysis of Power Cables for Wind Turbine Application (전자장해석을 이용한 풍력발전용 전력 케이블의 전자기적 고찰)

  • Kim, Ji-Hyun;Cho, Sung-Ho;Lee, In-Woo
    • 한국신재생에너지학회:학술대회논문집
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    • 2006.06a
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    • pp.257-260
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    • 2006
  • This paper presents electromagnetic finite element analysis of power cables for wind turbine application. Eddy current losses are calculated due to high currents along metallic part, and dielectric strength on power cables is investigated for case study, which suggests the optimal cabling configuration for wind turbine construction.

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FRICTION AND WEAR AT SLIDING CERAMIC SURFACES

  • Kong, Hosung
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 1992.06a
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    • pp.1-20
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    • 1992
  • 1. Ceramics as engineering Materials Ceramic \ulcorner :'material based on inorganic non-metallic compounds' Oxygen, Carbon, Nitrogen with metal (Al, Si) -cheap, plentiful and widespread element in the Earth -dirt: ceramic

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Distribution of Metallic Elements Contamination in River Deposits and Farmland in the Vicinity of an Abandoned Korean Mine (폐광산 인근 농경지 및 하천 퇴적토의 중금속 오염 특성)

  • Lee, Hwan;Lee, Yoonjin
    • Economic and Environmental Geology
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    • v.53 no.2
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    • pp.133-145
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    • 2020
  • Soil in mine waste-rock fields, and at the pithead, sediments and farmlands around an abandoned mine in the Chungcheong Province of South Korea were investigated to assess the distribution of metallic elements and to understand the scope of the pollution. Reddening was observed from the mine up to a distance of 61 m. Losses of waste rock around the mine were assessed over a section of 1800 ㎥. Yellowish precipitates on the bottom of a stream were identified as ferrihydrite and goethite. For anions, a mean sulfate ion level over 773.6 mg/L was found during August in the river water samples. Mine drainage at the site was shown to have a pH of 4.9 and a sulfate concentration of 1557.8 mg/L during the August rainy season. A possible cause of the metallic element contamination in the mine is waste-rock loss, because mine waste-rock is located on the slope in this area. In conclusion, the total soil area to be treated, based on the amount that exceeded the recommended Korean soil pollution levels, was assessed to be 10,297 ㎡.

Chemical characteristics of ions and trace metallic element of PM2.5 in Busan metropolitan area (부산지역 $PM_{2.5}$의 이온 및 미량 금속성분의 화학적 특성)

  • 전보경;서정민;최금찬
    • Journal of Environmental Health Sciences
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    • v.27 no.4
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    • pp.63-71
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    • 2001
  • PM 2.5/ samples were measured at two sites, Hadan(suburban site) and Anrak (roadside site) in Busan area. PM 2.5/ sampling was performed for 24-hour intervals by the FH9.5 particulate sampler. Aerosol samples were collected on PTFE filter. A total of 60 particulate samples were collected, dad samples were measured for Particulate mass concentration, metallic elements (Cr, Mn, Ni. Cu. Se, Fe, Pb, and Zn) and waer-soluble elements (C $l^{[-10]}$ , N $O_{3}$$^{[-10]}$ ,S $O_{4}$$^{2-}$, N $H_{4}$$^{+}$, $Ca_{2}$$^{+}$, $Mg_{2}$$^{+}$ and $^{+}$.Mass concentration in Hadan ranged 24.23~57.12 $\mu\textrm{g}$/㎥ and 60.22~72.12 $\mu\textrm{g}$/㎥m Yellow Sand Events. Major cations in Hadan and Anrak site is N $H_{4}$$^{+}$and N $a^{+}$ respectively. SO42$^{[-10]}$ was the abundant specie in the PM 2.5 fraction for Hadan site an dAnrak site. Hadan site showed igher concentration in S $O_{4}$$^{2.1}$ and N $H_{4}$ $^{+}$ In Anrak site the concentration of S $O_{4}$/sip 2-/and N $a^{+}$ was higher than other ions Prominent metallic elements were Fe and Pb in two sites. Principal component analysis showed that main source of PM 2.5 aerosol particles was non-metal related source which was resulted in relating elements as Cr, Ni, and Pb at Hadan site, Anrak site also has resulted PM2.5 aerosol paricles source, which was related its element like Zn, and Ni,. The SAS package analysis also showed that long-range transport effect at Hadan area due to Yellow Sand Event by the prevailing weaterlies.ling weaterlies.

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The Formation Behavior of Non-metallic Inclusion in the Ce-added Hyper Duplex STS (Hyper Duplex STS 중 Ce 첨가 시 비금속개재물 생성거동)

  • Hong, S.H.;Jang, P.Y.;Park, Y.M.;Byun, S.M.;Kim, K.T.;You, B.D.
    • Transactions of Materials Processing
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    • v.19 no.5
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    • pp.311-319
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    • 2010
  • Rare earth metal Ce has a relatively low melting point and high specific gravity. Because of its significantly high affinity to oxygen, nitrogen and sulfur, it is highly usable as a steel refining agent. However, because Ce compound has relatively high specific gravity, it is difficult to be separated from molten steel through floatation, and it degrades the purity of molten steel, or may clog the nozzle in continuous casting. Such problem may be solved by using an appropriate deoxidation agent together with Ce and settling molten steel sufficiently after refining. Thus a fundamental study in the formation behavior of non-metallic inclusion in Ce added Hyper Duplex STS melts was investigated. The addition amount of Ce, melt temperature were considered as experimental variables. A main non-metallic inclusion in mother alloy is 51(wt%MnO) - 27.6(wt%SiO$_2$)- 10.9(wt%$Cr_2O_3$). Non-metallic inclusion was dramatically decreased and the particle size was fined as the amount of Ce increased. Moreover (%MnO) and (%SiO$_2$) of non-metallic inclusion were decreased. But (%$Al_2O_3$)were relatively increased. The number of non-metallic inclusion were decreased and the large particle size were increased by increasing the temperature of molten steel.

Efficient FE-Analysis Method with Equivalent Models for Metallic Sandwich Plates with Inner Dimpled Shell Subject to 3-Point Bending (등가 모델을 이용한 3점 굽힘 하중을 받는 딤플형 금속 샌드위치판재의 효율적 해석)

  • Seong D. Y.;Jung C. G.;Yoon S. J.;Yang D. Y.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2005.05a
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    • pp.130-133
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    • 2005
  • Efficient finite element method has been introduced for metallic sandwich plates subject to 3-point bending. A full model 3-point bending FE-analysis shows that plastic behavior of inner structures appears only at the load point. So, Unit structures of sandwich plates are defined to numerically calculate the bending stiffness with recurrent boundary condition of pure bending. And then equivalent models with same bending stiffness and strength of full models are designed analytically. It is demonstrated that results of both models are almost same and FE analysis method with equivalent models can reduce analysis time effectively.

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