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그리드 환경하에서 고성능 컴퓨팅을 이용한 열유동 해석 기법에 관한 기초연구
홍승도(Seung Do Hong),이대성(Dae Sung Lee),이재룡(Jae Ryong Lee),하만영(Man Yeong Ha),이상산(Sang San Lee) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.11
For simulation of three-dimensional turbulent flow with LES and DNS takes much time and expense with<br/> current available computing resources. It is nearly impossible to simulate turbulent flow with high Reynolds<br/> number. So, the emerging alternative is the Grid computing for needed computation power and working<br/> environment. In this study, the CFD code was parallelized to adapt it for the parallel computing under the Grid<br/> environment. In the first place, the Grid environment was built to connect the PC-Cluster facilities belong to<br/> the different institutions using communication network system. And CFD applications were calculated to<br/> check the performance of the parallel code developed for the Grid environment. Although it is a fundamental<br/> study, it brings about a important meaning as first step in research of the Grid.
평판 위에서 움직이는 물방울에 대한 분자동역학 시뮬레이션
홍승도(Seung Do Hong),하만영(Man Yeong Ha) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
Water covers 70% of the earth's surface and the human body consist of 75% of it. It is clear that water is one of the prime elements responsible for life on earth. Over the last 30 years or so, numerous studies have attempted to find out more about the water microscopically. In this paper, we investigated how the receding and advancing contact angle of the moving water droplet changes on a solid surface having various LJ epsilon parameters. To observe the dynamic contact angle history, a body force applied to all water molecules after obtained the water droplet in equilibrium with the solid surface. We obtained the density profile and receding and advancing contact angle of the moving water droplet.
원자적으로 균일한 평판 위에서 움직이는 물 액적에 대한 분자동역학 시뮬레이션
홍승도(Seung Do Hong),하만영(Man Yeong Ha) 대한기계학회 2009 大韓機械學會論文集B Vol.33 No.8
The variation in the shape of water droplet moving on atomistically smooth solid surface in the presence of a constant body force is simulated using molecular dynamics simulation. We investigated how the advancing and receding contact angle of the moving water droplet changes on a solid surface having various characteristic energies. From the MD simulation results, we obtained the density profile defined as the number of water molecules at a given position. Then, assuming the water droplet periphery to be a circle, we calculated the contact angles by using a nonlinear fitting of the half-density contour line. The present simulation clearly shows the different profile of the advancing and receding contact angle for these three different interaction potential between the water droplet and the solid surface.
주기적 줄무늬 패턴을 가지는 나노 구조물 위의 수액적에 대한 분자동역학 시뮬레이션
최호진(Hojin Choi),홍승도(Seung-Do Hong),윤현식(Hyun-Sik Yoon),하만영(Man-Yeong Ha) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
The research of the wetting phenomena has been studied for several decades widely. If the surface has ideal thing, wetting characteristics of a water droplet like contact angle is described by Young's equation. However in case of the roughness surface, it is well known, the contact angle between the wall and water droplet change. This means that we could control the hydrophilic property using physical and chemical treatment of the surface. Many researchers had studied the wetting phenomena of the surface with nano-structure using theoretical method, experiment, and computational method. In the computational method, they used molecular dynamics simulation or Monte-Carlo simulation mainly. And they calculated the water droplet on the heterogeneous or pillar patterned surfaces. In the present study, we simulated the water droplet on stripe patterned surfaces. Then we evaluated the contact angle for different shape variables.
최호진(Ho Jin Choi),홍승도(Seung Do Hong),하만영(Man Yeong Ha),윤현식(Hyun Sik Yoon) 대한설비공학회 2010 설비공학 논문집 Vol.22 No.2
We investigated the variation in contact angle of a nano-sized water droplet on a nano stripe-patterned surface using molecular dynamics simulation. By changing the height and width of the stripe pillar, and the gap width of the stripes, we observed the contact angle of water droplet in equilibrium. When the surface energies were 0.1 and 0.3 ㎉/㏖, the calculated contact angles were in good agreement with the Cassie and Baxter equation. However, when the surface energy is 0.5 ㎉/㏖, the contact angles are observed to be perturbed along the Cassie and Baxter equation.