• Title/Summary/Keyword: cross sectional

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Minimum Heat Dissipation of HTS Current Lead Having Partial Current Sharing Region (일부 전류분류영역을 가짐으로서 최소 열손실을 갖는 초전도 전류도입선)

  • Seol, S.Y.;Her, K.S.
    • Proceedings of the KSME Conference
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    • 2001.11b
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    • pp.131-136
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    • 2001
  • In this paper, a high-temperature superconductor(HTS) current lead operating in current sharing mode is described. The minimum heat dissipation and the optimum safety factor(cross-sectional area) is obtained analytically for partial current sharing HTS leads. It is assumed that the current lead is in conduction cooled state, and the sheath material is the alloy of silver and gold. The reduced cross-sectional area results partial current sharing state, and consequently reduces conduction heat transfer, but the Joule heat generation is increased. The optimized HTS current lead is different from the conventional copper leads. In the copper leads, the minimum heat dissipation is obtained for the zero gradient of temperature at warm end. However, the temperature gradient at warm end is not zero when the HTS lead operates at minimum dissipation state.

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Procedural Method for Detecting Conic Sections in the Intersection of Two Tori (두 토러스의 교차곡선에서 이차곡선의 발견을 위한 절차적 방법)

  • 김구진;김명수
    • Korean Journal of Computational Design and Engineering
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    • v.5 no.4
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    • pp.336-346
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    • 2000
  • This paper presents a geometric method that can detect and compute all conic sections in the intersection of two tori. Conic sections contained in a torus must be circles. Thus, when two tori intersect in a conic section, the intersection curve must be a circle as well. Circles in a torus are classified into profile circles, cross-sectional circlet, and Yvone-Villarceau circles. Based on a geometric classification of these circles, we present a procedural method that can detect and construct all intersection circles between two tori. All computations can be carried out using simple geometric operations only: e.g., circle-circle intersections, circle-line intersections, vector additions, and inner products. Consequently, this simple structure makes our algorithm robust and efficient, which is an important advantage of our geometric approach over other conventional methods of surface intersection.

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Structural Characteristics of a Hybrid Composite Carbody of Korean Tilting Train by Weight Load (한국형 틸팅열차용 복합재 차체의 하중적재에 따른 구조적 특성고찰)

  • Kim Jung-Seok;Jeong Jong Cheol;Han Jeong-Woo;Lee Sang-Jin;Kim Seung-Cheol;Seo Sung-Il
    • Journal of the Korean Society for Railway
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    • v.9 no.3 s.34
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    • pp.251-256
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    • 2006
  • This paper explains manufacturing process, analysis and experimental studies on a hybrid composite carbody of Korean tilting train. The composite carbody with length of 23m was manufactured as a sandwich structure composed of a aluminium honeycomb core and woven fabric carbon/epoxy faces. In order to evaluate deformational behavior of the composite carbody, the static load test under vertical load has been conducted. From the test, the vertical deflection an겨 cross sectional deformation of the carbody were analysed and measured. The maximum deflection along the side sill was 9.25mm in the experiment and 8.28mm in the analysis. The maximum cross sectional deformation was measured 5.42mm at carbody center in lateral direction and 4.06mm at roof center in vertical direction.

Improvement of Interfacial Adhesion of Metal Plated Synthetic Fabrics for Electromagnetic Wave Shielding by Using Cold Plasma (저온 플라즈마 처리에 의한 전자파 차폐성 금속화 합성섬유의 계면 밀착성 개선)

  • 천태일
    • Textile Coloration and Finishing
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    • v.10 no.2
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    • pp.8-17
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    • 1998
  • In this study we have examined electroless chemical plating on the plasma grafted poly [ethylene terephathalate](PET) fabric in order to improve the interfacial adhesion between metal and fiber. The vapour phase of acrylic acid introduced on the PET surface and the graft polymerization was carried out by using cold plasma, resulting in the grafting yield of 0.8-1.3 wt%. The carboxyl group of the plasma grafted was identified by FT-IR-ATR spectra. The Interfacial adhesion was related to the carboxyl group. After electroless chemical plating of nickel, it showed that the more the carboxyl, the better the interfacial adhesion. Comparing to the untreated, the plasma grafted fabric showed fairly good interfacial adhesion(5B grade, ASTM D3359) . The shielding effect of electromagnetic wave showed 95dB. The shielding effect depends on the fabric structure, the surface structure, and the cross sectional shape of fibers. The dense fabric structure, the etched surface like a microcrater, and the trigonal cross sectional shape were prefered.

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Impedance Analysis and Experimental Study of a Solenoid Eddy Current Sensor to Detect the Cross-sectional Area of Non-ferromagnetic Stranded Conductors (비자성 연선도체의 단면적을 검출하기 위한 솔레노이드 와전류 센서의 임피던스 해석 및 실험적 연구)

  • Kim, S.D.;Shim, J.M.
    • Journal of Sensor Science and Technology
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    • v.6 no.2
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    • pp.87-94
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    • 1997
  • Impedance analysis of a Solenoid sensor to detect the cross-sectional area of non-ferromagnetic stranded conductors is described in this paper. To inspect electromagnetic characteristics of conductive materials, a nondestructive test eddy current sensor with an encircling coil is chosen. As solving Maxwell equation, normalized impedance response of the sensor within a conducting rod is modeled and the results are expanded to the stranded wires. Geometrical property affecting on stranded structure is considered and a numerical and experimental study is also presented.

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Zeroth-Order Shear Deformation Micro-Mechanical Model for Periodic Heterogeneous Beam-like Structures

  • Lee, Chang-Yong
    • Journal of Power System Engineering
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    • v.19 no.3
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    • pp.55-62
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    • 2015
  • This paper discusses a new model for investigating the micro-mechanical behavior of beam-like structures composed of various elastic moduli and complex geometries varying through the cross-sectional directions and also periodically-repeated along the axial directions. The original three-dimensional problem is first formulated in an unified and compact intrinsic form using the concept of decomposition of the rotation tensor. Taking advantage of two smallness of the cross-sectional dimension-to-length parameter and the micro-to-macro heterogeneity and performing homogenization along dimensional reduction simultaneously, the variational asymptotic method is used to rigorously construct an effective zeroth-order beam model, which is similar a generalized Timoshenko one (the first-order shear deformation model) capable of capturing the transverse shear deformations, but still carries out the zeroth-order approximation which can maximize simplicity and promote efficiency. Two examples available in literature are used to demonstrate the consistence and efficiency of this new model, especially for the structures, in which the effects of transverse shear deformations are significant.

Free Vibrations and First Critical Loads of Tapered Columns (변단면 기둥의 자유진동 및 최소임계하중 해석)

  • 이병구;오상진;모정만;김헌상
    • Journal of KSNVE
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    • v.2 no.3
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    • pp.203-211
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    • 1992
  • The main purpose of this paper is to present both the natural frequencies and the first critical loads of tapered columns. The ordinary differential equation governing the free vibration for tapered columns under compressive axial force is derived. Three kinds of cross sectional shape are considered in the governing equation. The Runge-Kutta method and determinant search method are used to perform the integration of the differential equation and to determine the natural frequencies, respectively. Additionally, the bisection method is used to determine the critical loads. In numerical examples, the effects of compressive axial force on the natural frequencies of tapered columns are investigated varying the end conditions. The first critical loads of tapered columns are determined on the basis of dynamic concepts. The first critical loads of tapered columns are determined on the basis of dynamic concept. The effects of cross sectional shapes are shown and some typical mode shapes are also presented.

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유한요소법을 이용한 전방압출공정의 내부결함에 관한 연구

  • 김태형;김병민;강범수;최재한
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1992.04a
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    • pp.79-83
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    • 1992
  • According to the variation of hydrostatic pressure on the central axis of deformable material, the V-shaped central bursting defect may be created on extrusion or drawing processes. The process factors whichaffect the generation of defects are die semi-angle, reduction ratio of cross-sectional area, friction factor, material properties and so on. The combination of these factors can determine the prossibility of defect creation and the shape of various round holes which have been created inside already. By the rigid plastic finite element method, this paper describes the observations of change in shape of a round hole with process conditions suchas die semi-angle, reduction ratio of cross-sectional area and friction factorat the unsteady state of axi-symmetrical extrusion process when the round hole is alreadyexisted inside the original billet, and also, the effects of process factors are investigated to prevent the possible defects.

Minimum Cost Design of Reinforced Concrete Frames Using DCOC (DCOC를 이용한 RC 프레임의 최소경비설계)

  • 한상훈;구봉근;조홍동;오현수
    • Proceedings of the Korea Concrete Institute Conference
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    • 2000.04a
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    • pp.485-490
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    • 2000
  • This paper describes the application of discretized continuum-type optimality criteria (DCOC) for minimum-cost design of the reinforced concrete frame structures consisting of beams and columns. The cost of construction as objective function which includes the costs of concrete, reinforced steel and formwork is minimized. The design constraints include limits on the maximum deflection at a prescribed node, bending and shear strengths in beams, uniaxial bending strength of columns according to design codes(CEB/FIP, 1990). In the first stage, only beams with uniform cross-sectional parameters per span are considered. But the steel ratio is allowed to vary freely. The cross-sectional parameters and steel ratio in each column are assumed to be uniform for practical reasons. Optimality criteria is given based on the well known Kuhn-Tucker necessary conditions, followed by an iterative procedure for designs when the design variables are the depth and the steel ratio. The versatility of the DCOC technique has been demonstrated by considering numerical examples which have one-bay four-storey frame.

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AC Resistance(Rac) comparison between the new type of coil structure and the annular copper coil to maximize the conductor occupying ratio (고정자 권선 점적율을 극대화 하는 새로운 코일구조와 환형동선 코일구조간의 AC Resistance(Rac) 비교)

  • LEE, Eui-Chun;Kim, Yong-Hoon;LEE, Kang-Won;Lee, Su-Woong;Kwon, Soon-O
    • Proceedings of the KIEE Conference
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    • 2015.07a
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    • pp.784-785
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    • 2015
  • This paper proposes a new structure of coil to maximize the conductor occupting ratio(conductor cross sectional area than the cross sectional area inside the slot) of the magnetic core. Further, assuming a case in which the 3-D coil is applied to a real motor. Analyze the current density distribution of the coil conductor by electromagnetic analysis method. Finally the AC resistance was measured according to the frequency of the coils. This expereiment is to calculate a optimal operating frequency to obtain high efficiency operational frequency range of motor.

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