• 한국안전학회지
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• 제10권1호
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• pp.64-73
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• 1995

A preliminary study is performed in order to design an effective ventilation equipment for the control of possible pollutants in a workshop. To this end, the Patankar's SIMPLE methodology is used to investigate the flow characteristics of the contaminated thermal deflected jet which is encounted often in practical hood system. SIMPLE-Consistent algorithm is employed for the pressure-velocity coupling appeared in momentum equations. A two equation, k-$\varepsilon$ model is used for Reynolds stresses. The prediction data is compared well against the experimental results by Chang(1989). Considering the control of the wake due to its high turbulence together with the stagnant feature has been investigated in term of major parameters such as temperature and magnitude of the discharge velocity. Detailed discussions are made to reduce the size of the wake region which give rise to pollutant concentration stratification.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1996년도 춘계 학술대회논문집
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• pp.93-98
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• 1996

파랑중을 항주하는 Wigley 선형주위의 점성유동장을 수치적으로 해석하였다. Navier-Stokes 방정식을 유한차분법을 이용하여 차분화하고 압력과 속도의 연성은 MAC방법으로 처리하였다. 격자계로는 O-H헝 격자계를 사용하였으며 정수중에서 항주하는 결과를 다른 실험결과 및 계산결과와 비교하여 계산정도를 검증하였으며, 파랑이 선체주위의 유동장에 미치는 영향에 관하여 고찰하였다.

• 한국전산유체공학회지
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• 제3권2호
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• pp.17-26
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• 1998

The three-dimensional incompressible Navier-Stokes equations have been solved by a node-centered finite volume method with unstructured hybrid grids. The pressure-velocity coupling is handled by the artificial compressibility algorithm and convective fluxes are obtained by Roe's flux difference splitting scheme with linear reconstruction of the solutions. Euler implicit method with Jacobi matrix solver is used for the time-integration. The viscous terms are discretised in a manner to handle any kind of grids such as tetragedra, prisms, pyramids, hexahedra, or mixed-element grid. Inviscid bump flow is solved to check the accuracy of high order convective flux discretisation. And viscous flows around a circular cylinder and a sphere are studied to show the efficiency and accuracy of the solver.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.626-629
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• 2008

Numerical predictions on flow phenomena in pipe network systems have been considered as playing an important role in both designing and operating various facilities of piping or duct systems, such as water supply, tunnel or mine ventilation, hydraulic systems of automobile or aircraft, and etc. Traditionally, coupling conditions between junction and connected branches are assumed to satisfy conservation law of mass and to share an equal pressure at junction node. However, the conventional methodology cannot reflect momentum interactions between pipes sufficiently. Thus, a new finite volume junction treatment is proposed both to reflect the interchanges of linear momentums between neighbor branches at junction and to include the effect of wall at junction in present work.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.430-435
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• 2008

This research deals with the implementation hydrodynamic (HD) lubrication system with an integration of multibodydynamics (MBD) in order to analyze bearing lubrication characteristics such as pressure distribution and oil film thickness dynamically. The HD solver developed newly will transmit force and torque data to MBD solver, and receive position and velocity data from it continuously. After an analysis, we will verify the result with existing commercial software. Moreover, other functions like adjusting size of mesh grid, setting oil hole & groove effects, and consideration of thrust force will be introduced.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.442-447
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• 2008

This paper presents a new approach to simulate fluid-solid interaction problems involving non-matching interfaces. The coupling between fluid and solid domains with dissimilar finite element meshes consisting of 4-node quadrilateral elements is achieved by using the interface element method (IEM). Conditions of compatibility between fluid and solid meshes are satisfied exactly by introducing the interface elements defined on interfacing regions. Importantly, a consistent transfer of loads through matching interface element meshes guarantees the present method to be an efficient approach of the solution strategy to fluid-solid interaction problems. An arbitrary Lagrangian-Eulerian (ALE) description is adopted for the fluid domain, while for the solid domain an updated Lagrangian formulation is considered to accommodate finite deformations of an elastic structure. The stabilized equal order velocity-pressure elements for incompressible flows are used in the motion of fluids. Fully coupled equations are solved simultaneously in a single computational domain. Numerical results are presented for fluid-solid interaction problems involving nonmatching interfaces to demonstrate the effectiveness of the methodology.

• E2M - 전기 전자와 첨단 소재
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• 제8권2호
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• pp.136-143
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• 1995

With the contact angle of phase dropping epoxy resin on the inorganic filler(glass plate) surface treated with air plasma, we have studied about the interfacial wettability between epoxy resin and glass plate as a simple model of glass fiber reinforced composite materials. The contact angle on the inorganic filler surface varied with surface treatment conditions. The contact angle significantly depends on plasma treating time and environment temperature in the oven. From the view point of plasma treatment condition in this work, when discharge conditions were pressure 200mtorr, voltage 800V, magnetic flux density 8OGauss, optimum treatment time were proved as 3,4 and 5 minutes for the environment of >$80^{\circ}C$, >$100^{\circ}C$ and >$120^{\circ}C$, respectively.

• International Journal of Fluid Machinery and Systems
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• 제2권2호
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• pp.179-188
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• 2009

Recent development of high speed computers and use of optimization techniques have given a big momentum of turbomachinery design replacing expensive experimental cost as well as trial and error approaches. The surrogate based optimization techniques being used for aerodynamic turbomachinery designs coupled with Reynolds-averaged Navier-Stokes equations analysis involve single- and multi-objective optimization methods. The objectives commonly tried to improve were adiabatic efficiency, pressure ratio, weight etc. Presently coupling the fluid flow and structural analysis is being tried to find better design in terms of weight, flutter and vibration, and turbine life. The present article reviews the surrogate based optimization techniques used recently in turbomachinery shape optimizations.

• 전산구조공학
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• 제2권1호
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• pp.55-64
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• 1989

본 논문에서는 경계요소법과 비선형 유한요소법의 각 장점을 이용하여 반무한 영역을 가진 구조체의 해석방법을 논하였다. 여기서, 반무한 경계요소는 Melan의 반무한 평면에 대한 해로부터 구성하였다. 비선형 유한요소는 지하구조물에서 주로 접할 수 있는 탄소성 재료의 비균질성 또는 불규칙성을 모형화하기 위하여 사용하였다. 본 조합방법의 검증을 위하여 얕은 터널에 일정한 내압이 작용하는 경우를 택하여, 비선형 유한요소법과 조합방법의 결과를 비교하였다. 비교결과, 개발된 조합방법이 다른 해석방법에 비해 충분한 정확도를 가짐을 알 수 있었다.

• 동력기계공학회지
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• 제4권1호
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• pp.60-67
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• 2000

As the speed of rotating machines increases and also their weight decreases, the coupling between lateral and torsional vibrations must be considered. In the past, rotordynamics and geardynamics have tended to treat the lateral and torsional vibrations of the system elements as separate and decoupled mechanisms. In the paper, the coupled lateral-torsional free and forced vibration of rotors trained by gears is analyzed using finite element method. Also the complicated variation of the meshing stiffness as a function of contact point along the line of action is estimated correctly. The gear mesh model is assumed to be linear with constant average mesh stiffness.