• 대한기계학회논문집
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• 제10권2호
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• pp.247-256
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• 1986

본 연구에서는 종횡비가 0.2인 직각 밀폐용기내에서 소금물을 시험유체로 하여 양단의 온도 및 농도차가 수평방향으로 가해지는 경우(CASE 1,2) 밀폐용기내 에서의 유동현상과 열전달 특성을 온도 및 농도분포, 흐름의 가시화를 통해 실험적 으로 관찰, 조사하였다

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1487-1491
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• 2008

Detailed knowledge on the motion of blood cells flowing in micro-channels under simple shear flow and the influence of blood flow is essential to provide a better understanding on the blood rheological properties and blood cell aggregation. The microscopic behavior of red blood cell (RBCs) is numerically investigated using a fluid-structure interaction (FSI) method based on the Arbitrary-Lagrangian-Eulerian (ALE) approach and the dynamic mesh method (smoothing and remeshing) in FLUENT (ANSYS Inc., USA). The employed FSI method could be applied to the motions and deformations of a single blood cell and multiple blood cells, and the primary thrombogenesis caused by platelet aggregation. It is expected that, combined with a sophisticated large-scale computational technique, the simulation method will be useful for understanding the overall properties of blood flow from blood cellular level (microscopic) to the resulting rheological properties of blood as a mass (macroscopic).

• 제어로봇시스템학회논문지
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• 제11권9호
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• pp.789-794
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• 2005

This paper describes an algorithm for minimal turning complete coverage Path planning for cleaning robots. This algorithm divides the whole cleaning area by cellular decomposition, and then provides the path planning among the cells employing a flow network. It also provides specific path planning inside each cell guaranteeing the minimal turning of the robots. The minimal turning of the robots is directly related to the faster motion and energy saving. The proposed algorithm is compared with previous approaches in simulation and the result shows the validity of the algorithm.

• 전자공학회논문지CI
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• 제37권6호
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• pp.10-21
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• 2000

거리 변환(Distance Transform)을 수행할 수 있는 셀룰라 비선형 네트워크 구조와 특징 점들의 제적 상에서 거리 변환을 이용한 optical flow 검출 방법을 제안하였다. 움직이는 물체의 추적이나 카메라의 움직임 파악 같은 응용 분야에서는 수가 적더라도 정확하고 확실한 optical flow가 더 중요하다. 본 연구는 특징점들의 이동 궤적 상에서 거리 변환 기법을 이용하여 거리 변환 필드(Distance Transform Field)를 생성시키고 거리 변환 필드상에서 궤적의 움직인 거리 값과 방향을 추출함으로써 optical flow를 구하는 방법이다. 이 방법은 영상 정보를 거리 정보로 변환하여 사용하게 되므로 잡음의 영향을 적게 받으며 필요한 연산들이 아날로그 회로에 의해 처리되므로 처리 속도가 빠르고, 지역적 처리 특성을 갖기 때문에 하드웨어 구현이 용이하다는 특징이 있다. 또한, 본 연구에서는 제안한 알고리즘의 핵심부분을 하드웨어로 구현하기 위해 셀룰라 비선형 네트워크(Celluar Nonlinear Neural Network)구조를 제안하였다. 제안한 구조와 알고리즘을 검증하기 위해 다양한 영상과 환경에 대한 시뮬레이션을 수행하여 결과를 제시하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.627-632
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• 2000

Developing turbulent flows in a rotating 90 degree bend with square cross-section were measured by a hot-wire anemometer. The six orientation hot-wire technique was applied to measured the distributions of 3 mean velocities and 6 Reynolds stress components. Effects of Coriolis and centrifugal forces caused by the curvature and rotation of bend on the mean motion and turbulence structures were experimentally investigated Productive addition of Coriolis and centrifugal forces to the outward radial direction in the entrance region of bend increases the secondary flow intensity according to the rotational speeds. However, after 45 degree of bend, centrifugal force due to the rotation of bend may promote the break down of counter rotating vortex pair into multi-cellular pattern, thereby decreasing the production rate of turbulence energy and Reynolds stresses.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.542-546
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• 2008

In this study, we developed a whole cardiovascular system model combined with a Laplace heart based on the numerical cardiac cell model and a detailed arterial network structure. The present model incorporates the Laplace heart model and pulmonary model using the lumped parameter model with the distributed arterial system model. The Laplace heart plays a role of the pump consisted of the atrium and ventricle. We applied a cellular contraction model modulated by calcium concentration and action potential in the single cell. The numerical arterial model is based upon a numerical solution of the one-dimensional momentum equations and continuity equation of flow and vessel wall motion in a geometrically accurate branching network of the arterial system including energy losses at bifurcations. For validation of the present method, the computed pressure waves are compared with the existing experimental observations. Using the cell-system-arterial network combined model, the pathophysiological events from cells to arterial network are delineated.

• 한국도로학회논문집
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• 제12권4호
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• pp.11-16
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• 2010

보행교통류를 주제로 다양한 연구들이 진행되었지만 초기의 보행연구는 차량의 교통류이론을 그대로 적용하여 해석하기도 하였다. 최근 보행교통류에 대한 다양한 모형들이 제시되고 있으며, 특히 CA모형은 보행교통류를 위한 시뮬레이션 모형으로 빈번하게 사용되고 있다. 대표적인 CA 모형으로 가스입자의 움직임을 이용하여 양방향의 보행교통류를 설명하기도 하였는데 초기에는 정방형의 Gas-lattice 모형이 제안되었으며 이후에 정육방 Gas-lattice 모형을 이용하여 보행자의 움직임과 회피를 묘사하기도 하였다. 하지만 이러한 모형들은 보행자의 움직임을 편의임의보행으로 가정하였기 때문에 단일방향으로의 움직임만을 설명할 수 있었다. 본 연구에서 제시된 MLPM(the Multi-Layer Pedestrian Model)은 어떤 공간에서 복수개의 기종점을 가진 경우에도 현실적인 보행자의 움직임을 설명할 수 있는 모형이다.

• 한국해양학회지
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• 제28권1호
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• pp.17-23
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• 1993

회전반 위에서 상하경계면이 경사진 (${\beta}-effect$) 원통용기에 이층유체를 만들어 하층에 같은 밀도를 갖는 외부유체를 주입하여 경계면 변형에 따른 상층유체의 흐름을 관찰하였다. 상하층유체간의 경계면마찰을 최소화하여 하층유체운동(Sverdrup type) 에 따른 경계면의 변화에 적응하기 위한 상승유체 흐름은 internal Frounde Number($F_1$)에 민감하게 반응함을 보인다. 특히 $F_1$값이 6이상인 경우에는 상층유체운동 특성인 두 개의 폐쇄순환의 방향이 반대가 되어 서안경계류의 분리현상을 나타내고 있다. 서안에서의 분리 지점 역시 $F_1$값에 의존하며, 특히 $F_1{\;}~{\;}6$인 경우 가장 북쪽에서 분리되는 현상을 보였다.

• Wind and Structures
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• 제23권1호
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• pp.19-43
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• 2016

In the present study, a new methodology is presented to study the ride comfort and bridge responses of a long-span bridge-traffic-wind coupled vibration system considering stochastic characteristics of traffic flow and bridge surface progressive deterioration. A three-dimensional vehicle model with 24 degrees-of-freedoms (DOFs) including a three-dimensional non-linear suspension seat model and the longitudinal vibration of the vehicle is firstly presented to study the ride comfort. An improved cellular automaton (CA) model considering the influence of the next-nearest neighbor vehicles and a progressive deterioration model for bridge surface roughness are firstly introduced. Based on the equivalent dynamic vehicle model approach, the bridge-traffic-wind coupled equations are established by combining the equations of motion of both the bridge and vehicles in traffic using the displacement relationship and interaction force relationship at the patch contact. The numerical simulations show that the proposed method can simulate rationally the ride comfort and bridge responses of the bridge-traffic-wind coupled system; and the vertical, lateral, and longitudinal vibrations of the driver seat model can affect significantly the driver's comfort, as expected.

• Earthquakes and Structures
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• 제12권4호
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• pp.457-468
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• 2017

When studying the vibration of a suspension bridge based on the traffic-bridge coupled system, most researchers ignored the contribution of the pavement response. For example, the pavement was simplified as a rigid base and the deformation of pavement was ignored. However, the action of deck pavement on the vibration of vehicles or bridges should not be neglected. This study is mainly focused on establishing a new methodology fully considering the effects of bridge deck pavement, probabilistic traffic flows, and varied road roughness conditions. The bridge deck pavement was modeled as a boundless Euler-Bernoulli beam supported on the Kelvin model; the typical traffic flows were simulated by the improved Cellular Automaton (CA) traffic flow model; and the traffic-pavement-bridge coupled equations were established by combining the equations of motion of the vehicles, pavement, and bridge using the displacement and interaction force relationship at the contact locations. The numerical studies show that the proposed method can more rationally simulate the effect of the pavement on the vibrations of bridge and vehicles.