Im YoungMin

Luis Ángel (임 영민)

lal@cs.ucsb.edu

youngMin
 

My Portfolio

I am a computer scientist and software engineer interested in Computer Graphics, Computational Science (Scientific Computing), and Machine Learning. I am currently a graduate student at the University of California, Santa Barbara, where I am member of the Computational Applied Science Laboratory, advised by Prof. Frédéric Gibou.

Curriculum Vitae

Latest Projects

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Error-Correcting Neural Networks for Semi-Lagrangian Advection in the Level-Set Method

We present a machine learning framework that blends image super-resolution technologies with scalar transport in the level-set method. Here, we investigate whether we can compute on-the-fly data-driven corrections to minimize numerical viscosity in the coarse-mesh evolution of an interface. The proposed system's starting point is the semi-Lagrangian formulation. And, to reduce numerical dissipation, we introduce an error-quantifying multilayer perceptron. The role of this neural network is to improve the numerically estimated surface trajectory. To do so, it processes localized level-set, velocity, and positional data in a single time frame for select vertices near the moving front. Our main contribution is thus a novel machine-learning-augmented transport algorithm that operates alongside selective redistancing and alternates with conventional advection to keep the adjusted interface trajectory smooth. Consequently, our procedure is more efficient than full-scan convolutional-based applications because it concentrates computational effort only around the free boundary. Also, we show through various tests that our strategy is effective at counteracting both numerical diffusion and mass loss. In passive advection problems, for example, our method can achieve the same precision as the baseline scheme at twice the resolution but at a fraction of the cost. Similarly, our hybrid technique can produce feasible solidification fronts for crystallization processes. On the other hand, highly deforming or lengthy simulations can precipitate bias artifacts and inference deterioration. Likewise, stringent design velocity constraints can impose certain limitations, especially for problems involving rapid interface changes. In the latter cases, we have identified several opportunity avenues to enhance robustness without forgoing our approach's basic concept.

Submitted.

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A Hybrid Inference System for Improved Curvature Estimation in the Level-Set Method Using Machine Learning

We present a novel hybrid strategy based on machine learning to improve curvature estimation in the level-set method. The proposed inference system couples enhanced neural networks with standard numerical schemes to compute curvature more accurately. The core of our hybrid framework is a switching mechanism that relies on well established numerical techniques to gauge curvature. If the curvature magnitude is larger than a resolution-dependent threshold, it uses a neural network to yield a better approximation. Our networks are multilayer perceptrons fitted to synthetic data sets composed of sinusoidal- and circular-interface samples at various configurations. To reduce data set size and training complexity, we leverage the problem's characteristic symmetry and build our models on just half of the curvature spectrum. These savings lead to a powerful inference system able to outperform any of its numerical or neural component alone. Experiments with static, smooth interfaces show that our hybrid solver is notably superior to conventional numerical methods in coarse grids and along steep interface regions. Compared to prior research, we have observed outstanding gains in precision after training the regression model with data pairs from more than a single interface type and transforming data with specialized input preprocessing. In particular, our findings confirm that machine learning is a promising venue for reducing or removing mass loss in the level-set method.

Submitted.