• Title, Summary, Keyword: 속도포텐셜

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Path Planning for Mobile Robots Using Fuzzy Potential Field Method (퍼지 포텐셜 필드를 이용한 이동로봇의 경로 계획)

  • Woo, Kyoung-Sik;Park, Jong-Hun;Kim, Jin-Hwan;Huh, Uk-Youl
    • Proceedings of the KIEE Conference
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    • pp.1900-1901
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    • 2011
  • 본 논문은 이동로봇의 동적 장애물 회피를 위해 퍼지 포텐셜 필드 알고리즘을 제안하였다. 기존의 포텐셜 필드 알고리즘은 장애물의 위치와 속도에 따라 장애물과의 충돌 문제, 회피 경로 문제 및 목표지점으로의 도착시간 문제가 발생한다. 이를 보완하기 위해 퍼지시스템을 이용하여 포텐셜 필드 척력함수의 가중치를 장애물의 위치와 속도에 따라 변경함으로써 제안된 알고리즘의 효율성을 시뮬레이션을 통해 확인하였다.

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Aircraft Collision-Avoidance/Guidance Strategy in Dynamic Environments for Planar Flight (2차원 평면에서 이동장애물에 대한 항공기의 유도/회피기동 연구)

  • Rhee, Ihn-Seok
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.32 no.7
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    • pp.69-75
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    • 2004
  • An avoidance/guidance problem of an aircraft against moving obstacle is considered in two dimensional space. The aircraft is modelled as a point mass flying with constant speed. The lateral acceleration is assumed the control input. Artificial potential functions are applied to the terminal point and moving obstacles in order that repulsive forces and an attractive force are produced by the obstacles and the terminal point respectively. A real time guidance/avoidance law is proposed by using the potential forces and relative velocity. The guidance law for a logarithm potential function results the well-known proportional navigation law. The avoidance control command is inverse proportional to the time-to-go to the obstacle and turns the aircraft toward the negative direction of the line-of-sight change. The performance of the proposed guidance/avoidance law is verified with simulations.

Effects of Light, Temperature, Water Changes on Physiological Responses of Kalopanax pictus Leaves(V) - Physiological Responses by the Changes of Leaf Water Potential - (광, 온도, 수분 변화에 따른 음나무 엽의 생리반응(V) - 잎의 수분 포텐셜 변화에 따른 생리반응 -)

  • Han, Sang-Sup;Jeon, Doo-Sik;Sim, Joo-Suk;Jeon, Seong-Ryeol
    • Journal of Forest and Environmental Science
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    • v.22 no.1
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    • pp.76-82
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    • 2006
  • 1. This stuty was investigated in 6-year-old Kalopanax leaves in plantation forest. 2. The decrease in net photosynthesis rate began at -0.80 MPa water potential, and then approached zero at -2.50 MPa. The relative net photosynthesis rate which is 50% occurred at -1.70 MPa. The stomatal conductance increased temporarily until -1.00 MPa, and then rapidly decreased. At -2.50 MPa, the relative stomatal conductance was 7% of maximum value. 3. The stomatal transpiration rate increased temporarily until -1.00 MPa, and then rapidly decreased. At -2.50 MPa, the relative stomatal transpiration rate was about 17% of maximum rate. The water use efficiency rapidly decreased with decreasing water potential, and then approached about zero at -2.50 MPa. 4. With decreasing leaf water potential, the $CO_2$ content ratio. $C_i/C_a$ in intercellar rapidly increased. The vapor pressure deficit, VPD gradually increased until -2.00 MPa, and then rapidly increased.

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Flow Measurement and Analysis of the Waterjet Duct (물분사추진기 관내 유동계측 및 유동해석)

  • 왕정용;최희종;전호환;차상명
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • pp.240-243
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    • 2001
  • 괘도차량에 부착된 물분사추진기의 유동해석을 실험과 포텐셜해석 그리고 점성해석을 사용하여 그 결과를 비교하였다. 예인수조에서 여러 차량 전진속도에 대해서 임펠러 회전수를 조정하여 제트속도를 변화시키면서 덕트표면에서의 정압을 계측하였다. 이는 제트시스템의 효율을 추정하기 위함이고 관로를 통한 에너지분포를 알 수 있다. 점성유동해석을 위해 지배방정식은 비압축성 Navier-Stokes 방정식을 유한체적법을 사용하여 이산화하고 해석하였으며 난류영향은 표준 ĸ-$\varepsilon$난류모형을 사용하여 유동을 해석하고 실험결과 및 포텐셜 해석결과와 비교하였다.

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Wave Deformation by Submerged Flexible Circular Disk (몰수된 원형 유연막에 의한 파랑변형)

  • 조일형;김무현
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.12 no.3
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    • pp.116-129
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    • 2000
  • The interaction of incident monochromatic waves with a tensioned, flexible, circular membrane submerged horizontally below free surface is investigated in the frame of three-dimensional linear hydro-elastic theory. The velocity potential is split into two parts i.e. the diffraction potential representing the scattering of incident waves by a rigid circular disk and the radiation potential describing motion induced waves by elastic responses of flexible membrane. The fluid domain is divided into three regions, and the diffraction and radiation potentials in each region are expressed by the Fourier Bessel series. The displacement of circular membrane is expanded with a set of natural functions, which satisfy the membrane equation of motion and boundary conditions. The unknown coefficients in each region are determined by applying the continuity of pressure and normal velocity at the matching boundaries. The results show that various types of wave focusing are possible by controlling the size, submergence depth, and tension of membrane.

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Non-Quadratic Anisotropic Strain Rate Potential Defined in Plane Stress State (평면 응력 조건에서 정의된 비이차 비등방 변형률 속도 포텐셜)

  • Kim, D.;Kim, J.H.;Lee, Y.S.;Barlat, Frederic;Chung, K.
    • Transactions of Materials Processing
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    • v.20 no.5
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    • pp.369-376
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    • 2011
  • A non-quadratic anisotropic strain rate potential was introduced as a conjugate potential of the yield stress potential Yld2000-2d to describe anisotropic behavior of sheet metals, in particular, aluminum alloy sheets under plane stress state. This strain-rate potential takes into account the anisotropic yield stresses and R-values measured along the directions measured at 0, 45 and 90 degrees from the rolling direction, as well as the balanced biaxial yield stress and strain-rate ratio. The convexity of the strain-rate potential was completely proven. The strain-rate potential was applied for two anisotropic aluminum alloy sheets, AA6022-T4 and AA2090-T3. The results verified that the strain rate potential properly described the anisotropic behavior of aluminum alloy sheets and was closely conjugate of Yld2000-2d under the plane stress state.

Effects of a Submerged Block on the Sloshing of a Fluid in Rectangular Tanks (수중블럭이 사각형탱크의 자유수면 유동에 미치는 영향)

  • Choun, Young-Sun;Yun, Chung-Bang
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.191-200
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    • 1994
  • 사각형 유체저장탱크의 바닥에 놓여져 있는 사각형 블럭의 크기 및 위치가 자유수면의 유동진동수와 모드형상에 미치는 영향에 대하여 선형파이론을 적용하여 검토하였다. 유체의 영역을 3부분으로 나누고 각 영역에서의 속도포텐셜을 입사파와 블럭으로 인해 발생되는 반사파 및 전달파의 항으로써 표현하였다. 그리고 블럭에 의한 파의 반사율과 전달율은 유체영역의 경계에서 속도포텐셜과 유체입자의 속도가 연속인 조건을 사용하여 구하였다. 연구결과 블럭의 높이와 폭은 자유수면의 고유진동수에 크게 영향을 미치며 높이와 위치는 모드형상에 주로 영향을 준다. 블럭이 높고 폭이 넓을수록 고유 진동수는 감소하며 블럭이 높고 탱크의 벽면으로 이동할수록 모드형상은 크게 변한다.

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Simulation of Nonlinear Water Waves using Boundary Element Method (경계요소법을 이용한 비선형파의 재현)

  • 오영민;이길성;전인식
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.5 no.3
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    • pp.204-211
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    • 1993
  • Boundary element method is applied to simulate nonlinear water waves using Green's identity formula in a numerical wave flume. A system of linear equations is formulated from the governing equation and free surface boundary conditions in order to calculate velocity potential and water surface elevation at each nodal point. The velocity square terms are included in the dynamic free surface boundary condition. The free surface is treated as a moving boundary. the vertical variation of velocity potential being considered in calculating the time derivative of the velocity potential at the free surface. The present method is applied to simulate solitary wave and Stokes 2nd order wave, and shows excellent agreements with their theoretical values.

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Derivation of Extended Mild-Slope Equation Using Euler-Lagrange Equation (Euler-Lagrange 식을 사용한 확장형 완경사방정식 유도)

  • Lee, Changhoon;Kim, Kyu-Han
    • Journal of The Korean Society of Civil Engineers
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    • v.29 no.5B
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    • pp.493-496
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    • 2009
  • In this study, we derive the extended mild-slope equation in terms of the velocity potential using the Euler-Lagrange equation. First, we follow Kim and Bai (2004) who derive the complementary mild-slope equation in terms of the stream function using the Euler-Lagrange equation and we compare their equation to the existing extended mild-slope equations of the velocity potential. Second, we derive the extended mild-slope equation in terms of the velocity potential using the Euler-Lagrange equation. In the developed equation, the higher-order bottom variation terms are newly developed and found to be the same as those of Massel (1993) and Chamberlain and Porter (1995). The present study makes wide the area of coastal engineering by developing the extended mild-slope equation with a way which has never been used before.

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Analysis of Manoeuvrability of a Ship in Waves by 3-Dimensional Panel Method (3차원 파넬방법에 의한 파중 선박의 조종성능 해석)

  • S.P. Ann;K.P. Rhee
    • Journal of the Society of Naval Architects of Korea
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    • v.31 no.4
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    • pp.82-98
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    • 1994
  • A mathematical model for the hydrodynamic forces acting on the ship manoeuvring in waves is formulated and a numerical method for the problem is developed. The motion of a ship, which manoeuvres in waves, may be thought to have two components; one is a high frequency component due to encounter waves, and the other is a low frequency component due to manoeuvring motion. So the method of two time scale expansion is used to divide linear boundary value problem. For the effects of waves on the manoeuvring motion of a ship, only the second order drift forces are considered. The integral equation for the velocity potential is solved by 3 dimensional panel method and hydrodynamic forces are calculated by direct integral method.

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