Jooyoung Hahn

ORCID: 0000-0003-4357-1009
Publications
Citations
Views
---
Saved
---
About
Contact & Profiles
Research Areas
  • Medical Image Segmentation Techniques
  • Advanced Numerical Methods in Computational Mathematics
  • Advanced Numerical Analysis Techniques
  • Computer Graphics and Visualization Techniques
  • Image and Signal Denoising Methods
  • Lattice Boltzmann Simulation Studies
  • Computational Geometry and Mesh Generation
  • 3D Shape Modeling and Analysis
  • Computational Fluid Dynamics and Aerodynamics
  • Model Reduction and Neural Networks
  • Advanced Vision and Imaging
  • Image Retrieval and Classification Techniques
  • Numerical methods in inverse problems
  • Combustion and flame dynamics
  • Advanced Image Processing Techniques
  • Image and Object Detection Techniques
  • Advanced Mathematical Modeling in Engineering
  • Flow Measurement and Analysis
  • Underwater Vehicles and Communication Systems
  • Surface Roughness and Optical Measurements
  • Cell Image Analysis Techniques
  • Micro and Nano Robotics
  • Cell Adhesion Molecules Research
  • Electromagnetic Simulation and Numerical Methods
  • Random lasers and scattering media

Slovak University of Technology in Bratislava
2023-2025

Anstalt für Verbrennungskraftmaschinen List (Austria)
2017-2021

University of Graz
2011-2012

Nanyang Technological University
2009-2010

Korea Advanced Institute of Science and Technology
2006-2008

Minimization of functionals related to Euler's elastica energy has a wide range applications in computer vision and image processing. A high order nonlinear partial differential equation (PDE) needs be solved, the gradient descent method usually takes computational cost. In this paper, we propose fast efficient numerical algorithm solve minimization problems show variational denoising, inpainting, zooming. We reformulate problem as constrained problem, followed by an operator splitting...

10.1137/100803730 article EN SIAM Journal on Imaging Sciences 2011-01-01

The spatial interactions between malignant and immune cells in the tumor microenvironment (TME) play a crucial role cancer biology treatment response. Understanding these is critical for predicting prognosis assessing immunotherapy effectiveness. Conventional methods, which focus on local features, often struggle to achieve robust analysis due complex heterogeneous cellular distributions. We propose Topological Data Analysis (TDA)-based framework using both global features cells. For...

10.1101/2025.03.27.645762 preprint EN cc-by-nc-nd bioRxiv (Cold Spring Harbor Laboratory) 2025-04-01

In this paper, we propose the neural shortest path (NSP), a vector-valued implicit representation (INR) that approximates distance function and its gradient. The key feature of NSP is to learn exact (ESP), which directs an arbitrary point nearest on target surface. decomposed into magnitude direction, variable splitting method used each component gradient, respectively. Unlike existing methods learning itself, ensures simultaneous recovery We mathematically prove guarantees convergence in...

10.48550/arxiv.2502.06047 preprint EN arXiv (Cornell University) 2025-02-09

10.1007/s10915-011-9482-6 article EN Journal of Scientific Computing 2011-04-15

Variable splitting schemes for the function space version of image reconstruction problem with total variation regularization (TV-problem) in its primal and pre-dual formulations are considered.In formulation, while existence a solution cannot be guaranteed, it is shown that quasi-minimizers penalized asymptotically related to original TV-problem.On other hand, formulation family parametrized problems introduced parameter dependent contraction an associated fixed point iteration...

10.1088/0266-5611/30/5/055014 article EN Inverse Problems 2014-05-01

Magnetic resonance electrical impedance tomography (MREIT) is designed to produce high resolution conductivity images of an electrically conducting subject by injecting current and measuring the longitudinal component, Bz, induced magnetic flux density B = (Bx, By, Bz). In MREIT, accurate measurements Bz are essential in producing correct images. However, measured data may contain fundamental defects local regions where MR magnitude image small. These defective result completely wrong values...

10.1109/tmi.2005.862150 article EN IEEE Transactions on Medical Imaging 2006-01-31

10.1016/j.jvcir.2009.10.005 article EN Journal of Visual Communication and Image Representation 2009-10-22

Abstract In this paper, we aim to develop a comprehensive ignition model for three-dimensional (3D) computational fluid dynamics (CFD) combustion modeling in spark-ignited (SI) engines. the proposed model, consider following aspects separately spark process comprehensively. An electrical circuit is solved calculation of energy transferred plasma channel. The itself represented by particles monitoring its motion and ignitability. Heat diffusion from toward surrounding mixture calculated with...

10.1115/1.4044222 article EN Journal of Energy Resources Technology 2019-07-11

In this paper, we present a surface reconstruction via 2D strokes and vector field on the based two-step method. first step, from sparse drawn by artists given strokes, propose nonlinear interpolation combining total variation (TV) H 1 regularization with curl-free con- straint for obtaining dense field. second height map is obtained integrating in step. Jump discontinuities of gradients can be well reconstructed without any distortion. We also provide fast efficient algorithm solving...

10.4208/nmtma.2013.mssvm16 article EN Numerical Mathematics Theory Methods and Applications 2013-01-01

Abstract A cell‐centered finite volume method with the Soner boundary condition is proposed to compute signed distance function from a given surface in general three‐dimensional (3D) computational domains discretized by polyhedral cells. The governing equation bidirectional time‐relaxed eikonal and numerical based on semi‐implicit inflow‐implicit outflow‐explicit scheme. Numerical experiments confirm second order accuracy ‐norms for chosen examples smooth solutions. inclusion of has proven...

10.1002/nme.6888 article EN International Journal for Numerical Methods in Engineering 2021-11-23

Abstract The convoluted shape of the cerebral cortex makes it difficult to analyze and visualize neuronal activation area. One way overcoming this problem is use a spherical inflation method draw on surface. task mapping cortical surface sphere has several obstacles, namely, overlap between polygons surface, heavy computation demand, geometric distortions inherent in process. This article proposes three‐dimensional (3D) represented simplex mesh which does not have any minimizes as well time....

10.1002/ima.20140 article EN International Journal of Imaging Systems and Technology 2008-01-01

We propose a variational segmentation model based on statistical information of intensities in an image. The consists both local region-based energy and global order to handle misclassification which happens typical with assumption that image is mixture two Gaussian distributions. find ambiguous regions where might happen due small difference between Based restricted the regions, we design reduce misclassification. suggest algorithm avoid difficulty Euler-Lagrange equations proposed model.

10.12941/jksiam.2014.18.129 article EN Journal of the Korea Society for Industrial and Applied Mathematics 2014-06-25

In this paper, we propose to use the eikonal equation as a boundary condition when advective or normal flow equations in level set formulation are solved numerically on polyhedral meshes three-dimensional domain. Since method can signed distance function an initial condition, is suitable choice at time. Enforcing for later times eliminate need inflow conditions, which typically required transport equations. selected examples where exact solutions available, compare proposed with using...

10.2139/ssrn.4712362 preprint EN 2024-01-01

This paper proposes a theoretical framework for analyzing Modified Incomplete LU (MILU) preconditioners. Considering generalized MILU preconditioner on weighted undirected graph with self-loops, we extend its applicability beyond matrices derived by Poisson equation solvers uniform grids compact stencils. A major contribution is, novel measure, the \textit{Localized Estimator of Condition Number (LECN)}, which quantifies condition number locally at each vertex graph. We prove that maximum...

10.48550/arxiv.2501.00245 preprint EN arXiv (Cornell University) 2024-12-30

<p style='text-indent:20px;'>A numerical method for solving diffusion problems on polyhedral meshes is presented. It based a finite volume approximation with the degrees of freedom located in centers computational cells. A gradient defined by least-squares minimization each cell, where we suggest restricted form case discontinuous coefficient. The flux balanced proposed without numerically computing itself at faces cells order to find normal diffusive flux. To apply parallel computations...

10.3934/dcdss.2020350 article EN Discrete and Continuous Dynamical Systems - S 2020-05-15
Coming Soon ...