• Journal of the Institute of Convergence Signal Processing
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• v.24 no.2
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• pp.97-102
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• 2023

Numerical simulations have been performed to investigate the hydrodynamic characteristics of the rudder since they play an important role in naval architecture fields. Although some values such as hydrodynamics forces can be measured easily in the towing tanks, it is difficult to obtain the detailed information of the flow fields such as pressure distribution, velocity distribution, vortex generation from experiments. In the present study, the effects of hydrodynamic coefficients and Reynolds number acting on the rudder were studied by using Computational Fluid Dynamics(CFD). Ansys fluent, one of commercial CFD solvers, solves the Navier-Stokes equations and the k-epsilon turbulence model is selected for the viscous model to solve RANS equations. At first, drag coefficients and lift coefficient for different angle of attack are obtained by using a CFD commercial code for KCS rudder. Secondly, the 2-D lift coefficients and drag coefficients are compared with 3-D coefficients at the same conditions. Thirdly, the effects of Reynolds number on the hydrodynamic forces are investigated.

• Proceedings of the Korean Society of Computer Information Conference
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• 2024.01a
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• pp.403-406
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• 2024

본 논문에서는 비눗방울에 나타나는 반사와 굴절 효과를 상용 게임엔진인 유니티 쉐이더(Unity shader)를 사용하여 구현하고 다양한 배경에서 합성할 수 있는 효율적인 프레임워크를 제안한다. 본 논문에서 제안하는 방법은 계산량이 큰 유체 시뮬레이션을 이용하지 않고, 스넬(Snell)의 법칙을 이용하여 박막 내부의 굴절 벡터를 계산하고, 막 표면의 표현을 위해 다양한 텍스처(Texture)를 적용하였으며, vertex의 조정을 통해 비눗방울 자체의 움직임을 나타낼 수 있다. 결과적으로 실시간으로 높은 품질의 비눗방울을 표현할 수 있기 때문에 게임뿐만 아니라 가상현실 및 다양한 실시간 애플리케이션에 활용될 수 있다.

• Journal of the Korea Computer Graphics Society
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• v.25 no.3
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• pp.105-113
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• 2019

Physically-based fluid simulation takes a lot of time for high resolution. To solve this problem, there are studies that make up the limitation of low resolution fluid simulation by using deep running. Among them, Super-resolution, which converts low-resolution simulation data to high resolution is under way. However, traditional techniques require to the entire space where there are no density data, so there are problems that are inefficient in terms of the full simulation speed and that cannot be computed with the lack of GPU memory as input resolution increases. In this paper, we propose a new method that divides and classifies 2D smoke simulation data into the space using the quad tree, one of the spatial partitioning methods, and performs Super-resolution only required space. This technique accelerates the simulation speed by computing only necessary space. It also processes the divided input data, which can solve GPU memory problems.

• Tunnel and Underground Space
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• v.8 no.3
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• pp.194-199
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• 1998

This research was aimed to figure out the trend of dust diffusion at open pit limestone mine for assessing the environmental impacts on the high voltage power transmission line. It is rather easy to assess the dust generation and size distribution of limestone dust at the blasting site, but it is very hard to assess the expected area of dust diffusion and amount of dust fall by the distances from the dust source. In this research, a 3-dimensional fluid dynamic simulation software (3D-Flow) was used for analysing the above mentioned matters to assess the impacts to the insulators on the transmission tower by the blasting dust. It was verfied that the 3D-Flow is reliable tool for simulating dust movement, and the limestone dust is not much hazardous to the power transmission line.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.4
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• pp.251-257
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• 2011

In the present study, a 3-dimensional (3D) numerical model was developed to mimic the micro porous structure of a geological $CO_2$ storage reservoir. Especially, 3D modeling technique assigning random pore size to a 3D micro porous structure was devised. Numerical method using CFD (computational fluid dynamics) was applied for the 3D micro porous structure to calculate supercritical $CO_2$ flow field. The three different configurations of 3D micro porous model were designed and their flow fields were calculated. For the physical conditions of $CO_2$ flow, temperature and pressure were set up equivalent to geological underground condition where $CO_2$ fluid was stored. From the results, the characteristics of the supercritical $CO_2$ flow fields were scrutinized and the influence of the micro pore configuration on the flow field was investigated. In particular, the pressure difference and consequent $CO_2$ permeability were calculated and compared with increasing $CO_2$ flow rate.

• Journal of computational fluids engineering
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• v.14 no.3
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• pp.63-68
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• 2009

The motion of a rising liquid droplet is different that of a bubble motion. Treatment of liquid drops is more complex because internal motion must be considered. A 3D unstructured CFD code has been developed to solve incompressible N-S equation for the droplet simulation. This front-tracking consideration which the interface is tracked explicitly is very available to apply for not only exact interface topology but also the high schmidt number issue, such as $CO_2$ dissolution. This paper is forced on the zig-zag motion of the liquid droplet. The simulation shows that if the rising droplet is located at the corner of the zig-zag path, the velocity is low and shape of the droplet is more spherical shape, results in the less drag coefficient. Twin horse shoe vortexes behind the rising droplet are presented and the topology of the droplet is compared with an experimental result during one period of the path.

• Journal of Korea Multimedia Society
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• v.13 no.9
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• pp.1382-1390
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• 2010

We can see interactions between rigid body and fluid every day, anywhere. This kind of rigid body-fluid simulation is one of the most difficult problems in physically-based modeling, mainly due to heavy computations. In this paper, we present a real-time dynamics model for simulating stone skipping, which is a popular rigid body-fluid interaction in the real world. In comparison to the previous works, our improved dynamics model supports the rotation of the stones and also computes frictional forces with respect to the air. We can simulate a realistic result for various user input by using proposed model. Additionally, we present a water surface model to show more realistic ripples interactively. Our methods can be easily adapted to other interactive dynamics systems including 3D game engines.

• Proceedings of the Korean Society of Computer Information Conference
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• 2024.01a
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• pp.391-393
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• 2024

본 논문에서는 수중에 존재하는 몰입형 에이전트의 움직임을 사실적으로 표현하고 수중 오브젝트들과의 상호작용에서 나타나는 외력을 시각적으로 표현할 수 있는 프레임워크를 제안한다. Unity3D와 HTC Vive를 이용해 사용자의 움직임을 추적하고 수중 물리적 요소인 부력, 저항력, 매그너스 효과를 몰입형 에이전트에 적용시켜 사용자로 하여금 수중에 작용하는 외력을 사실적으로 인지할 수 있게 한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.7
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• pp.1630-1638
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• 2015

In this paper, we propose a GPU-based interactive and plausible visualization method for the silt and landslide simulation results computed with SPH. By empirical experiments, we verify that our GPU-accelerated screen space mesh method can be effectively used for visualizing the landslide disaster simulation. The method proposed in this paper make it possible to overcome the limitation of previous simulations where the experience obtained by trials and errors plays the most important roles. Because the realtime visualization enables interactive observation of simulation results and efficient data assimilation, the accuracy of the simulation can be significantly improved in an efficient way.

• Journal of the Korea Computer Graphics Society
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• v.14 no.4
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• pp.27-33
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• 2008

Physics-based graphic techniques are used when simulating and rendering natural phenomena such as smoke, water and flame with computational physics. We propose novel methods which render simulated particle data fast onto 3D using tetrahedron splat. We calculate the position and the normal vector of splat by SPH(smoothed particle hydrodynamics) method then we reconstruct splat into quadrangular pyramid to reduce seam. We implement this technique for SPH fluid simulation, and animate natural flow of water successfully.