• Title/Summary/Keyword: potential fields

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OBTAINING BOUNDARY TANGENTIAL COMPONENTS OF POTENTIAL MAGNETIC FIELDS BY A VARIATIONAL METHOD

  • CHOE G. S.
    • Journal of The Korean Astronomical Society
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    • v.31 no.2
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    • pp.89-93
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    • 1998
  • An attempt is made to find the boundary tangential components of potential magnetic fields without constructing solutions in the entire domain. In our procedure, the magnetic energy is expressed as a functional of tangential and normal magnetic fields at the boundary and is minimized by the variational principle. This paper reports a preliminary study on two dimensional potential fields above a plane.

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Large-Scale Realtime Crowd Simulation Using Image-Based Affordance and Navigation Potential Fields (이미지 기반의 유도장과 항해장을 활용한 실시간 대규모 군중 시뮬레이션)

  • Ok, Soo-Yol
    • Journal of Korea Multimedia Society
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    • v.17 no.9
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    • pp.1104-1114
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    • 2014
  • In large-scale crowd simulations, it is very important for the decision-making system of manipulating interactive behaviors to minimize the computational cost for controlling realistic behaviors such as collision avoidance. In this paper, we propose a large-scale realtime crowd simulation method using the affordance and navigation potential fields such as attractive and repulsive forces of electromagnetic fields. In particular, the model that we propose locally handles the realistic interactions between agents, and thus radically reduces the cost of expensive computation on interactions which has been the most problematic in crowd simulation. Our method is widely applicable to the expression and analysis of various crowd behaviors that are needed in behavior control in computer games, crowd scenes in movies, emergent behaviors of evacuation, etc.

3-D Magnetostatic Field Analysis Using Boundary Element Method (경계요소법을 이용한 3차원 정자장 해석)

  • 전기억;고창섭;정현교;한송엽
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.40 no.12
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    • pp.1211-1217
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    • 1991
  • A three dimensional magnetostatic probodm is analyzed using the boundary element method and the magnetic scalar potential are employed in order to reduce the size of system matrix. Although the total magnetic scalar potential gives very accurate solutions at inner and outer regions of magnetic materal, the method has limitation on application because the magnetic scalar potential due to applied magnetic field sources is hard to be obtained. The reduced magnetic scalar potential gives more or less inaccurate solutions inside the magnetic material but very accurate solutions outside. Hence it can be concluded that the reduced magnetic scalar potential is very useful when the magnetic fields of outside of magnetic fields of outside of magnetic material are interested. It is also shown, from the numerical example, that the linear shape function gives more efficient solutions than the constant shape functions.

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The calculatation of induced voltages and electromagnetic fields in 154kV sub (154kV 변전소의 전자계와 유도전압계산)

  • Choi, Chang-Hyek;Han, Poong
    • Proceedings of the KIEE Conference
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    • 1998.07e
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    • pp.1659-1662
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    • 1998
  • This paper is to analyze electromagnetic fields on a 154kV substation system and induced voltages on the substation fence when the network is operating in a normal condition or a fault condition in which one phase is shorted with the overhead ground wire. Also, changing the scalar potential and electromagnetic fields that are changed in accordance with changing resistivity and permeability of ground are studied. A finding of the study is that the scalar potential and electromagnetic fields are raised near the tower: The values of electric field on the corner of fence and at the edge of the ground grid are higher than other locations.

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A Computational Model for a Neuronal Membrane Considering the Extremely Low Frequency and Mobile Phone Frequency Electromagnetic Field Effect (극 저주파 및 휴대전화 전자파 환경 변수를 고려한 새포막 활동 전위 모형)

  • 서영준;이은주;안재목;이용업;황태금;이재선;서정선
    • Journal of Biomedical Engineering Research
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    • v.24 no.4
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    • pp.347-354
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    • 2003
  • In this paper, a computational method of an action potential including the effect of extremely low frequency and mobile phone (external) electromagnetic fields is Proposed. The method is based on the Hodgkin and Huxley model, applies the effect of the electromagnetic fields on the action Potential in terms of a binding factor into the injection current of the model, and calculates the Strength-Duration curve from numerical experiments for a frequency range of electromagnetic fields. In the numerical experiments, the coupled ordinary differential equations of the action potential and the state variables are solved solf-consistently by using Runge-Kutta Fehlberg method. The range of the frequency considered is from 1Hz through 100Hz and of 900MHz, which is specific for a mobile Phone. The Strength-Duration curves resulted showed good agreements with the equation suggested by Hodgkin and Huxley.

Mode I Field Intensity Factors of Infinitely Long Strip in Piezoelectric Media

  • Kwon, Soon-Man;Lee, Kang-Yong
    • Journal of Mechanical Science and Technology
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    • v.14 no.8
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    • pp.845-850
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    • 2000
  • We consider the problem of determining the singular stresses and electric fields in a piezoelectric ceramic strip containing a Griffith crack under in-plane normal loading within the framework of linear piezoelectricity. The potential theory method and Fourier transforms are used to reduce the problem to the solution of dual integral equations, which are then expressed to a Fredholm integral equation of the second kind. Numerical values on the field intensity factors are obtained, and the influences of the electric fields for PZT-6B piezoelectric ceramic are discussed.

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Estimation of Agricultural Water Demand in Hwanghae South Province, North Korea (북한 황해남도지역 농업용수 수요량의 추정(관개배수 \circled2))

  • 장민원;정하우
    • Proceedings of the Korean Society of Agricultural Engineers Conference
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    • 2000.10a
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    • pp.175-180
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    • 2000
  • The purposes of this study were to determine an algorithm for estimating agricultural water demand of remote sites using remote sensing data and to apply it to Hwanghae South Province and estimate the present and potential water demand for agriculture use. 3 Landsat-5 TM images and DEM(100${\times}$100mm) were used for classification of the existing land cover and land suitability analysis for paddy fields. Also, 20 years meteorological data of North Korea were used for calculating the potential evapotranspiration by Blaney-Criddle eq. and net water demand. The results showed that the present and potential agricultural water demand and the developable area for paddy fields is about 89,300㏊.

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Numerical Analysis on the Deformation of Free Surface of Magnetic Fluid (자성유체의 자유표면의 변형에 관한 수치해석)

  • Nam S.W.;Kamlyama S.
    • 한국전산유체공학회:학술대회논문집
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    • 1995.10a
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    • pp.132-137
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    • 1995
  • Numerical analysis is conducted on the deformation of free surface of magnetic fluid. Steady magnetic fields are induced by a circular current loop. Governing equations of magnetic fields are solved by using the concept of vector potential. The free surface of magnetic fluid is formed by the balance of surface force, gravity, pressure difference, magnetic normal pressure and magnetic body force. The deformations of free surface of magnetic fluid are qualitatively clarified. And, the patterns of steady non-uniform magnetic fields induced by a circular current loop are quantitatively presented.

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OBSERVING MAGNETIC FIELDS ON LARGE SCALES

  • RUDNICK LAWRENCE
    • Journal of The Korean Astronomical Society
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    • v.37 no.5
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    • pp.329-335
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    • 2004
  • Observations of magnetic fields on scales up to several Mpc are important for understanding cluster and large-scale structure evolution. Our current census of such structures is heavily biased - towards fields of several $\mu$G, towards fields in deep potential wells, and towards high inferred field strengths m cooling flow and other clusters from improper analysis of rotation measure data. After reviewing these biases, I show some recent results on two relics that are powered in very different ways. I describe new investigations that are now uncovering weak diffuse fields in the outskirts of clusters and other low density environments, and the good prospects for further progress.

Numerical Signal Prediction and Calibration Using the Theory of a Current-Type Electromagnetic Flowmeter for Two-Phase Slug Flow (슬러그 2상유동에서 전류형식 전자기유량계 수치적 신호예측 및 보정)

  • Ahn Yeh-Chan;Oh Byung Do;Kim Jong-Rok;Kim Moo Hwan;Kang Deok-Hong
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.29 no.6 s.237
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    • pp.671-686
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    • 2005
  • The transient nature and complex geometries of two-phase gas-liquid flows cause fundamental difficulties when measuring flow velocity using an electromagnetic flowmeter. Recently, a current-sensing flowmeter was introduced to obtain measurements with high temporal resolution (Ahn et al.). In this study, current-sensing flowmeter theory was applied to measure the fast velocity transients in slug flows. The velocity fields of axisymmetric gas-liquid slug flow in a vertical pipe were obtained using Volume-of-Fluid (VOF) method, and the virtual potential distributions for the electrodes of finite size were also computed using the finite volume method for simulating slug flow. The output signal prediction for slug flow was carried out from the velocity and virtual potential (or weight function) fields. The flowmeter was numerically calibrated to obtain the cross-sectional liquid mean velocity at an electrode plane from the predicted output signal. Two calibration parameters are proposed for this procedure: a flow pattern coefficient and a localization parameter. The flow pattern coefficient was defined by the ratio of the liquid resistance between the electrodes for two-phase flow with respect to that for single-phase flow, and the localization parameter was introduced to avoid errors in the flowmeter readings caused by liquid acceleration or deceleration around the electrodes. These parameters were also calculated from the computed velocity and virtual potential fields. The results can be used to obtain the liquid mean velocity from the slug flow signal measured by a current-sensing flowmeter.