• Journal of the Korea Computer Graphics Society
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• v.25 no.2
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• pp.11-18
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• 2019

In this paper, we propose a framework that can perform acceleration collision detection efficiently by using a cone based collision area in a particle-based system which requires collision detection with many objects. Three conditions determine particle and cone-based collision regions: 1) If there is a cone position within the radius of the adjacent particle, 2) In the case where the position of the adjacent particle exists in the cone area, 3) When adjacent particles exist between two vectors forming a cone area. As a result, it is defined that when the above conditions are all satisfied, the particle and the region of a cone have collided. In this paper, we automatically update the area of the cone, which is the collision detection area, according to the particle movement. Determine the direction and length of the cone based on the position and velocity of the particle to calculate the dynamic change of the cone. Collision detection is performed quickly using only the particles in the finally calculated area. The acceleration method proposed in this paper is simple to implement because it is executed with a closed form equation instead of explicitly creating the tree data structure, and collision inspection performance is improved in all results.

• Proceedings of the Korean Society of Computer Information Conference
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• 2019.01a
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• pp.333-335
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• 2019

본 논문에서는 많은 개체와의 충돌검사를 요구하는 입자 기반 시스템에서 부채꼴 영역의 동적인 변화를 이용하여 효율적으로 충돌검사를 가속화시킬 수 있는 프레임워크를 제안한다. 부채꼴 영역의 동적인 변화를 계산하기 위해 입자의 위치와 속도를 이용하여 부채꼴의 영역을 결정하였으며, 이 영역 내에 있는 입자들만을 이용하여 충돌 검사를 빠르게 수행한다. 본 연구에서 제안하는 가속화 방법은 트리 자료구조를 명시적으로 만들지 않고, 닫힌 형태 방정식(Closed form equation)으로 실행되기 때문에 간단하게 구현되며 모든 결과에서 충돌검사 성능이 3배 정도 개선되었다.

• Journal of Korean Society for Atmospheric Environment
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• v.27 no.6
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• pp.681-691
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• 2011

The size distributions of smoke particles from fire are prerequisite for the studies on fire detection and adverse health effects. Above the flame of the fire, coagulation dominates and the smoke particles grow from 1 to 50 nm up to 100 to 3,000 nm, sizes ranging from the free-molecular regime to the continuum regime. The characteristics of the agglomeration of the smoke particles are well known, independently for each of the free-molecular and continuum regimes. However, there are not many systematic studies in the entire regime by the complexity of the mechanisms. The purpose of this work is to find the characteristics of the development of the size distribution of smoke particles by agglomeration in the entire size range covering the free-molecular regime, via transition regime, to the near-continuum and continuum regime for each variation of parameters such as fractal dimension, primary particle size and dimensionless coagulation time. In this work, the dynamic equation for the discrete-size spectrum of the particles was solved using a nodal method based on the modification of a sectional method. In the calculation, the collision frequency function for the entire regime, which is derived by using the concept of collision volume and general enhancement function, was applied. The self-preserving size distribution for the entire regime is compared with the ones for the free-molecular or continuum regimes for each variation of the parameters.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.8
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• pp.818-822
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• 2008

The purpose of this study is to develop realistic painting simulation in real-time as well as to represent the thickness of the deposited paint on the surface. The Gaussian model is used for a painting deposition model to calculate the thickness of paints. For a painting simulation, rather than implementing particle systems, we propose a new heuristic algorithm for painting process based on a few number of rays. After we find the collision points of the rays with an environment, we compute the painted area using flood-fill searching method on the texture map and visualize paint effects. We analyzed time complexity of our method to verify that our system is suitable for real-time VR applications.

• Proceedings of the Korean Society of Computer Information Conference
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• 2023.01a
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• pp.395-398
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• 2023

본 논문에서는 물리 기반 옷감 시뮬레이션과 SPH(Smoothed particle hydrodynamics) 기반의 유체 시뮬레이션 간의 상호작용에서 표현되는 다양한 물리적 효과를 GPU 기반으로 빠르게 표현할 수 있는 프레임워크를 제안한다. 기존 기법과는 다르게 수치적 안정성을 개선하기 위해 CCD(Continuous collision detection)를 활용하였으며, 모든 연산이 GPU에서 동작하기 때문에 매우 빠르게 옷감과 유체의 상호작용 장면인 다공성 재질, 기공 흐름, 흡수, 방사, 확산을 모델링할 수 있다.