• 제목/요약/키워드: Optimal taper angle

검색결과 12건 처리시간 0.022초

일부 전류분류 영역을 갖는 테이퍼 형상 전류도입선의 최적 형상에 대한 연구 (The Optimum Shape of Taper HTS Current Lead Having Partial Current Sharing Region)

  • 허광수;설승윤
    • 한국초전도저온공학회:학술대회논문집
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    • 한국초전도저온공학회 2003년도 추계학술대회 논문집
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    • pp.185-189
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    • 2003
  • The purpose of this study is to obtain the optimal operating condition of conduction cooled taper shape high-temperature superconductor (HTS) current lead operated in current sharing mode. In our previous study, we discovered that the optimal operating condition of constant cross-section area HTS current lead is in the current sharing state, and in optimal condition, the temperature gradient at warm end is not zero. The analysis result of taper HTS current lead is quiet similar to the constant area HTS current lead. The minimum dissipation of taper HTS current lead is not influenced by taper angle, however the optimal operation condition is varied with taper angle.

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유한요소법을 이용한 증기터빈용 최적 테이퍼 스터드 볼트에 관한 연구 (Research on Optimal Taper Stud Bolts for Steam Turbines Using the FEM)

  • 이부윤;김태완
    • Journal of Advanced Marine Engineering and Technology
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    • 제24권2호
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    • pp.8-16
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    • 2000
  • The thread load distribution as applied to large stud bolts for steam turbines is investigated using the finite element method. The stress concentration in tapered threads is studied with varying prestress and taper angle. Based upon the thread load distribution, the optimal taper angles to reduce the stress concentration are determined for various prestresses. The presented finite element model is validated by comparing results of the calculated thread load with analytic ones. The optimal taper angles obtained from this research can be used in designing tapered threads of large stud bolts for steam turbines.

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방전가공을 이용한 미세구멍 가공 시 절연액, 축전용량과 초음파 부가에 따른 가공특성 (Machining Characteristics of Micro-EDMed Holes According to Dielectric Fluid, Capacitance and Ultrasonic Vibrations)

  • 서동우;이상민;주종남;박민수
    • 한국정밀공학회지
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    • 제24권12호
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    • pp.42-49
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    • 2007
  • When micro holes are machined by EDM, machining characteristics of machined holes are changed according to the machining conditions. Typical machining conditions are the kind of dielectric fluids, capacitance and ultrasonic vibrations. They influence electrode wear, machining time, radial clearance and taper angle. In this paper, machined holes whose depths are 300, 500, $1000\;{\mu}m$ are observed for each machining conditions. Using deionized water as a dielectric fluid makes electrode wear small, machining time short, radial clearance large and taper angle small. High capacitance makes electrode wear high. Ultrasonic vibrations make electrode wear large, machining time short, radial clearance small and taper angle small. From the results of experiments, the optimal machining conditions were obtained to machine highly qualified micro holes.

Transient Response of The Optimal Taper-Flat Head Slider in Magnetic Storage Devices

  • Arayavongkul, R.;Mongkolwongrojn, M.
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 2004년도 ICCAS
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    • pp.990-994
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    • 2004
  • This paper presents a method to predict the transient characteristic of the air lubricated slider head in a hard disk drive by using optimization technique. The time dependent modified Reynolds equation based on the molecular slip flow approximation equations was used to describe the fluid flow within the air bearing and the implicit finite difference scheme is applied to calculate the pressure distribution under the slider head. The exhaustive search combined with the Broyden-Fletcher-Goldfarb-Shanno method were employed to obtain optimum design variables which are taper angle, rail width and taper length in order to keep the forces and moments acting on the slider head in dynamic equilibrium. The results show that the optimal head slider of the magnetic head has good stability characteristic that can reach the steady state within 0.5 microsecond.

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마이크로 펌프용 디퓨져/노즐의 유동 특성에 관한 CFD 해석 (CFD Analysis on the Flow Characteristics of Diffuser/Nozzles for Micro-pumps)

  • 김동환;한동석;정시영;허남건;윤석진
    • 설비공학논문집
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    • 제17권6호
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    • pp.544-551
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    • 2005
  • The flow characteristics have been numerically investigated for various shapes of the diffuser/nozzles which are used for a valveless micro-pump. The important parameters considered in this study are the throat width ($15\~120\mu$m), the taper angle ($3.15\~25.2^{\circ}$), and the diffuser length ( $600\~4,800\mu$m), and the size of the middle chamber ($1\~16mm^2$). To find the optimal values for these parameters, steady state calculations have been performed assuming the constant pressure difference between the inlet and exit of the flow For the taper angle and the throat width, it is found that there exists an optimum at which the net flow rate is the greatest. The optimal taper angle is in the range of $10\~20^{\circ}$ for all the pressure differences; and the throat width indicates an optimal value near $75\mu$m for the case of 35 kPa pressure difference. The net flow rate is also influenced by the size of the middle chamber. With decreasing chamber size, the net flow rate is reduced because of the interference between two streams flowing into the middle chamber. The unsteady pulsating flow characteristics for a micro-pump with a given diffuser/nozzle shape have been also investigated to show the validity of the steady state parametric study.

텅스텐카바이드 미세축의 전해가공 시 최적가공조건 선정 (Optimal Machining Condition of WC-Microshaft Using Electrochemical Machining)

  • 최세환;류시형;최덕기;주종남
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2002년도 추계학술대회 논문집
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    • pp.245-249
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    • 2002
  • Tungsten carbide microshaft is used as various micro-tools in MEMS because it has high hardness and good rigidity. In this study, experiments were performed to produce tungsten carbide microshaft using electrochemical machining. $H_2SO_4$solution was used as electrolyte because it can dissolve tungsten and cobalt simultaneously. Optimal electrolyte concentration and machining voltage satisfying uniform shape and large MRR of workpiece were found. For one-step machining, the immersion depth over 1 mm was selected for avoidance of concentration of electric charge at the tip of the microshaft. The limit diameter with good straightness was shown and an empirical formula for WC-microshaft machining was suggested. By controlling the various machining parameters, a straight microshaft with 30 $\mu\textrm{m}$ diameter, over 1 mm length and under 0.5$^{\circ}$ taper angle was obtained.

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AWJ에서 혼합챔버 형상이 절단성능에 미치는 영향 (Effects of Mixing Chamber Shape on Cutting Performance in AWJ)

  • 이효렬;곽용길;김화영;안중환;여명헌
    • 한국생산제조학회지
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    • 제20권5호
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    • pp.535-540
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    • 2011
  • It is well known that abrasive waterjet (AWJ) was developed as a kind of high-density energy processing technologies. AWJ is used to obtain cutting quality of various materials such as metal, ceramics, glass and composite materials within a short manufacturing time because of the characteristics of heatless and noncontact processing. However, surface roughness and dimension error like round, burr, taper vary severely according to the processing conditions such as pressure, cutting speed, orifice diameter, stand off distance and abrasive flow rate. In this paper, the effect of the shape of mixing chamber on surface quality is studied. Three types of mixing chamber - round, parabolic, elliptical - are suggested and each performance is compared to that of cylindrical mixing chamber experimentally. From the result, is proved to be the optimal mixing chamber in the aspect of surface quality the parabolic one.

전해 가공을 이용한 WC 미세축 제작 (WC Micro-shaft Fabrication Using Electrochemical Etching)

  • 최세환;류시형;최덕기;주종남
    • 한국정밀공학회지
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    • 제21권6호
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    • pp.172-178
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    • 2004
  • Tungsten carbide microshaft can be used as various micro-tools for MEMS because it has high hardness and high rigidity. In this study, experiments are performed to produce tungsten carbide micro-shaft using electrochemical etching. H$_2$SO$_4$ solution is used as electrolyte because it can dissolve tungsten and cobalt simultaneously. Optimal electrolyte concentration and machining voltage satisfying uniform shape, good surface quality, and high MRR of workpiece are experimentally found. By controlling the various machining parameters, a straight micro-shaft with 5 ${\mu}{\textrm}{m}$ diameter, 3 mm length, and 0.2$^{\circ}$taper angle was obtained.

Flutter characteristics of axially functional graded composite wing system

  • Prabhu, L.;Srinivas, J.
    • Advances in aircraft and spacecraft science
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    • 제7권4호
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    • pp.353-369
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    • 2020
  • This paper presents the flutter analysis and optimum design of axially functionally graded box beam cantilever wing section by considering various geometric and material parameters. The coupled dynamic equations of the continuous model of wing system in terms of material and cross-sectional properties are formulated based on extended Hamilton's principle. By expressing the lift and pitching moment in terms of plunge and pitch displacements, the resultant two continuous equations are simplified using Galerkin's reduced order model. The flutter velocity is predicted from the solution of resultant damped eigenvalue problem. Parametric studies are conducted to know the effects of geometric factors such as taper ratio, thickness, sweep angle as well as material volume fractions and functional grading index on the flutter velocity. A generalized surrogate model is constructed by training the radial basis function network with the parametric data. The optimized material and geometric parameters of the section are predicted by solving the constrained optimal problem using firefly metaheuristics algorithm that employs the developed surrogate model for the function evaluations. The trapezoidal hollow box beam section design with axial functional grading concept is illustrated with combination of aluminium alloy and aluminium with silicon carbide particulates. A good improvement in flutter velocity is noticed by the optimization.

ModelCenter를 이용한 QTP-UAV 프롭로터 블레이드 형상 최적설계 (Design Optimization of QTP-UAV Prop-Rotor Blade Using ModelCenter)

  • 강희정
    • 항공우주시스템공학회지
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    • 제11권4호
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    • pp.36-43
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    • 2017
  • 쿼드틸트 무인기에 적용되는 프롭로터 블레이드 형상 최적설계를 수행하였다. 형상 최적설계 프로세스 통합은 ModelCenter(R) 프로그램을 이용하였으며, 최적설계 과정에서 성능해석은 CAMRAD-II를 사용하였다. 목적함수는 제자리비행 및 전진비행 모드에서 성능효율 최대화로 설정하였으며, 제한조건은 소요 동력 및 피치로드 하중 값이 기본 형상 값보다 작게 되도록 설정하였다. 설계변수로는 블레이드 루트 코드길이, 테이퍼비, 비틀림 각의 기울기 및 각도, 하반각, 끝단 형상 생성을 위한 파라볼릭 계수, 하반각과 끝단형상이 적용되는 블레이드 스팬위치, 블레이드 단면을 구성하는 익형의 위치로 구성하였다. 최적 설계 결과 기준 형상 대비 제자리비행 효율은 1.6%, 전진 비행 효율은 13.6% 향상된 프롭로터 블레이드 형상을 도출할 수 있었으며, 피치로드 하중은 약 30% 감소하였다.