• 대한조선학회논문집
• /
• 제58권2호
• /
• pp.90-96
• /
• 2021

In this study, the method of determining the state of grid points in the adaptable surface particle method based on grid system developed as a free-surface tracing method was improved. The adaptable surface particle method is a method of determining the state of the grid point according to the shape of the free-surface and obtaining the intersection of the given free-surface and grid line where the state of the grid point changes. It is difficult to determine the state of grid points in the event of rapid flow, such as collision or separation of free-surfaces, and this study suggests a method for determining the state of current grid points using the state of surrounding grid points where the state of grid point are known. A grid layer value was assigned sequentially to a grid away from the free-surface, centering on the boundary cell where the free-surface exists, to identify the connection information that the grid was separated from the free-surface, and to determine the state of the grid point sequentially from a grid away from the free-surface to a grid close to the free-surface. To verify the improved method, a numerical analysis was made on the problem of dam break in which a sudden collision of free-surface occurred and the results were compared, and the results were relatively reasonable.

• Food Science and Biotechnology
• /
• 제16권5호
• /
• pp.759-764
• /
• 2007

To investigate the effect of soaking and particle sizes on the properties of rice flour and gluten-free rice bread, wet-milled (WRF, dried at $20^{\circ}C$) and dry-milled rice flours (DRF) were passed through sieves (45 or 100 mesh). Soaking of the rice grains affected the particle size distribution of flour passed through the same size screen. The L and b values of WRF were higher than those of DRF and were not changed with decreasing particle sizes, but DRF increased L and decreased b values. The initial pasting temperatures and setback viscosities of both flours decreased with decreasing particle sizes. The swelling powers at $100^{\circ}C$ increased with decreasing particle sizes in DRF, but maintained in WRF. Starch granules were observed on the surface of flour particles in WRF. The apparent viscosity of WRF paste exhibited 3-5 times higher than that of DRF. Thus, wet milled rice flour with smaller particle sizes (${\phi}<150\;{\mu}m$) showed better properties for making gluten-free rice bread.

• 대한기계학회논문집
• /
• 제15권1호
• /
• pp.252-261
• /
• 1991

본 연구에서는 2상 횡분류의 평균 유동특성을 비교적 정확히 예측할 수 있는 방법을 제시하는데 있다. 이를 위하여 2상 기체 분류속에 유입되는 자유흐름의 질량 유입을 Keffer와 Baines의 유입함수를 이용하기로 하며, 입자와 기체분류사이의 궤적 이탈을 고려하기로 한다. 이런 모델을 이용하여 2상 횡분류의 분출초기의 입자와 기 체분류의 속도비(particle to gas velocity ratio at the jet exit)가 유동에 미치는 영향을 알아보고자 한다.

• 대한조선학회논문집
• /
• 제54권1호
• /
• pp.26-33
• /
• 2017

In this study, the surface marker method, one of the particle tracking methods, used to track the free surface is extended to cover the more general cases easily including the collision and separation of the free surface. In surface particle method to redistribute particles effectively using the grid system, the free surface is composed of the sum of quadrilaterals having four curves where fixed markers are placed at ends of each curve. Fixed markers are used to know how curves are connected to each other. The position of fixed markers can move as the free surface deforms but all fixed markers cannot be deleted during all time of simulation to keep informations of curve connection. In the case of the collision or separtion of the free surface where several curves can be intersected disorderly, severe difficulties can occur to define newly states of curve connection. In this study, the adaptable surface parTicle method without fixed markers is introduced. Intersection markers instead of the fixed markers are used to define quadrilaterals. The position of the intersection markers is defined to be the intersection point between the free surface and the edge of the grid and it can be added or deleted during the time of simulation to allow more flexibilities. To verify numerical schemes, two flow cases are simulated and the numerical results are compared with other's one and shown to be valid.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2004년도 춘계학술대회 논문집 전기설비전문위원
• /
• pp.105-108
• /
• 2004

This paper describes the influence of conducting particle in the coaxial cylindrical electrodes under alternating voltage condition investigated using breakdown electric field and electro magnetics simulation method. Simulated particle-location in GIS chamber were the particle on electrode, the particle on enclosure and free moving particle. As results, it was founded that in case of breakdown electric field of the GIS chamber, breakdown electric field of particle on electrode was the lowest, that of free moving particle was middle and that of particle on enclosure was the highest. And in case of the electric field analysis with particle locations, electric field of particle on electrode was the highest that of lifted particle was middle and that of particle on enclosure was the lowest. This results can offer a practical reference ra the insulation design of domestic GIS.

• 한국전산유체공학회지
• /
• 제13권1호
• /
• pp.28-34
• /
• 2008

A particle method recognized as one of the gridless methods has been developed to investigate the nonlinear free-surface motions interacting to the structures. The method is more feasible and effective than convectional grid methods for solving the non-linear free-surface motion with complicated boundary shapes. The right-handed side of the governing equations for incompressible fluid, which includes gradient, viscous and external force terms, can be replaced by the particle interaction models. In the present study, the developed method is applied to the dam-broken problem on dried- and wet-floor and its adequacy will be discussed by the comparison with the experimental results.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2007년도 추계 학술대회논문집
• /
• pp.258-263
• /
• 2007

A particle method recognized as one of the gridless methods has been developed to investigate the nonlinear free-surface motions interacting to the structures. The method is more feasible and effective than convectional grid methods for solving the non-linear free-surface motion with complicated boundary shapes. The right-handed side of the governing equations for incompressible fluid, which includes gradient, viscous and external force terms, can be replaced by the particle interaction models. In the present study, the developed method is applied to the dam-broken problem on dried- and wet-floor and its adequacy will be discussed by the comparison with the experimental results.

• 한국해양공학회지
• /
• 제21권6호
• /
• pp.53-58
• /
• 2007

A particle method, recognized as one of gridless methods, has been developed to investigate non-linear free-surface motions interacting with structures. This method is more feasible and effective than conventional grid methods for solving flow fieldswith complicated boundary shapes. The method consists of particle interaction models representing pressure gradient, diffusion, incompressibility, and the free-surface boundary conditions without grids. In the present study, broken dam problems with various viscosity values are simulated to validate the developed method.

• 조명전기설비학회논문지
• /
• 제15권5호
• /
• pp.14-19
• /
• 2001

전계해석법을 이용하여 나타내었다. 이때 모의한 GIS 챔버내 금속이물의 위치는 전극부착시, 외함부착시 그리고 자유운동시로 하였다. 그 결과 GIS챔버의 절연파괴전계의 경우, 전극에 파티클 부착시가 가장 작게 나타났고, 파티클 자유운동시가 중간, 외함에 파티클 부착시가 가장 작게 나타남을 알 수 있었다. 또한 파티클 위치에 따른 전계해석의 경우 전극에 파티클 부착시가 가장 크게 나타났고, 파티클 자유운동시가 중간, 외함에 파티클 부착시가 가장 작게 나타났다. 이 결과는 국내 GIS의 절연설계에 설제적인 참고자료가 될 것으로 사료된다.

• EDISON SW 활용 경진대회 논문집
• /
• 제5회(2016년)
• /
• pp.37-54
• /
• 2016

The methods for estimating the change of free energy in dissipative particle dynamics (DPD) are discussed on the basis of fluctuation theorems. Fluctuation theorems are tactics to evaluate free energy changes from non-equilibrium work distributions and have several forms, as proposed by Jarzynski, Crooks, and Bennett. The validity of these methods however, has been shown merely with the molecular dynamics or Langevin dynamics. In this study, the appropriate forms of fluctuation theorems for dissipative particle dynamics, which has similar structure to that of Langevin dynamics, are suggested using Liouville's theorem, and they are proved equivalent to original fluctuation theorems. Work distribution functions, which are probability distribution functions of works exerted on the system within the systematic change, are the basics of fluctuation theorems and their shapes are turned out to be dependent on the phase space trajectory of the change of the system. The reliability of Jarzynski and Crooks methods is highly dependent on the number of simulations to measure works and the shapes of the work distribution functions. Bennett method, however, can evaluate free energy changes even when Jarzynski and Crooks methods fail to do so.