Hello, I’m Changyong 🐱‍🏍

Changyong Song | Ph.D. Student @ Vanderbilt | Physics-based Animation, Simulation, AI

Hello, I’m Changyong Song — or just CHAYO, if you prefer.

I dream of exploring and designing diverse virtual worlds that feel as expressive and dynamic as the real one.

Currently, my research spans visual perception, physics-based animation, and AI-driven simulation, with a focus on bridging low-level physical dynamics and high-level perceptual understanding. I work across multiple modalities—including video, simulation outputs, and temporal signals—to build intelligent systems that not only analyze motion, but also generate physically plausible, perceptually meaningful experiences.

Contact Me!

Email :

chang-yong.song@vanderbilt.edu

LinkedIn :

www.linkedin.com

https://www.linkedin.com/in/chang-yong-song-b77862192/

Media/Code:

Chayoso - Overview

Ph. D. Student @ Vanderbilt (23. Fall ~ ). Chayoso has 3 repositories available. Follow their code on GitHub.

https://github.com/Chayoso

Chang-Yong Song

Share your videos with friends, family, and the world

https://www.youtube.com/@chang-yongsong1997

Education :

Vanderbilt Univ. (2023. 8. 23. ~ ) Ph.D. Student, Computer Science, GPA(3.981/4.0)

Advisor: Dr. David Hyde

Korea Univ. (2021. 3. ~ 2023. 2) Master of Science, Computer Science and Engineering, GPA(4.5/4.5)

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Thesis: MPM-Based Angular Animation of Particles using Polar Decomposition Theory

Kwangwoon Univ. (2015. 3. ~ 2021. 2) Bachelor of Science, Software, GPA(3.69/4.5)

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Grade Scholarship: 6, 7th semester

CV/Resume :

Click [here] to download my full curriculum vitae.

Portfolio:

Click the image below to open the full PDF

갤러리 보기

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Describe Lava’s localization with wax.

Use numeric animation for real data in Gen AI

Lava Localization Simulation Based on the Wax

TVCG Teaser Video:

Rendering results:

Sphere to Bunny & Duck to Cow:

D to Dragon:

TVCG:

Abstract : 

A Differentiable Material Point Method Framework for Shape Morphing

Abstract : 

Rendering results:

Sand particle example:

Snow with Car:

Primitive Rectangle (vs MPM):

Snowflakes (Neo-Hookean):

Mater’s Thesis: (Dissertation Defense: 11/17)

MPM-Based Angular Animation of Particles using Polar Decomposition Theory

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Grad School Projects

Abstract:

Automated Verification of Neural Network-Based Image Classifier for Stability Assurance in Graphics Rendering

We introduce a hybrid emotion recognition model that combines a pre-trained EfficientNet backbone with LSTM to capture the temporal dynamics of facial expressions. Unlike traditional static FER approaches, our model processes video sequences to classify valence and arousal into 21-level categories (from -10 to 10), enabling more accurate emotion estimation over time. The system is trained on the AFEW-VA dataset and outperforms baseline CNN-LSTM architectures, demonstrating the benefits of integrating spatio-temporal modeling in affective computing.

Results

 Compared to ResNet-50 baseline, our model improved the CCC score by over 60% (Valence: 0.31 → 0.97)

 EfficientNetLSTM achieved superior spatio-temporal representation despite smaller batch sizes and longer training time (7 hrs vs. 6 hrs)

Sequence-Based Facial Emotion Recognition using EfficientNet and LSTM

Compressible Flow Simulation using FEniCS

I implemented a simulation of compressible fluid flow using the finite element framework FEniCS. The governing equations include the full Navier–Stokes equations, accounting for variable density, momentum conservation, and thermal energy transport:

Mass conservation: ∂ρ/∂t + ∇·(ρu) = 0

Momentum equation includes both viscous and pressure forces with variable density

Energy conservation: accounts for heat convection and conduction

I derived and implemented the weak forms of these equations to suit finite element analysis.

During simulation, we encountered numerical instability, particularly in the advection term. To address this, we plan to incorporate SUPG (Streamline Upwind Petrov-Galerkin) stabilization, which mitigates oscillations and enhances robustness in advection-dominated flows.

This approach is expected to improve both convergence and physical realism of the compressible flow model.

Compressible Flow Implementation with FeniCS

Diffusion Model

GAN

Regression

Machine Learning Algorithms Implementation

Texture Volume Rendering with GLSL

This project implements GPU-based volume rendering using GLSL. Rays are cast through a 3D texture volume, with AABB (Axis-Aligned Bounding Box) intersection used to compute entry and exit points for ray traversal. The renderer supports alpha blending for accumulating semi-transparent voxel colors and isocontouring for visualizing surfaces of constant intensity. The combined use of ray marching and transfer functions allows for flexible and efficient real-time rendering of volumetric datasets.

Volume Rendering using GLSL

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Working Experience

Responsibilities / Highlights

Designed and implemented a GLTF-based physics engine that parses scene structures and physical properties directly from GLTF files.

Enabled real-time simulation of rigid body dynamics by mapping GLTF node hierarchies to physical entities with mass, inertia, and collision shapes.

Developed a custom parser to extract mesh, transform, and material data from GLTF assets for integration into the simulation pipeline.

Software Development Engineer Intern @ GrapiCar Inc.

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Undergrad School Projects

Implemented various real-time physics simulations using OpenGL and Unity 3D , focusing on deformable bodies and cloth-like behavior using the Mass-Spring System.

 Cloth Simulation

 Sphere Deformation

 Spring-Mass System

Physics Simulation using Mass-Spring System & Deformation

Implemented natural cubic spline and B-spline curve algorithms from scratch for smooth curve interpolation and modeling.

Developed an interactive system for curve construction, supporting user-defined control points and real-time visualization.

Explored properties of different spline types such as continuity (C¹, C²), local control, and smoothness.

Compared spline types through visual and mathematical analysis to understand their behavior and suitability in animation or modeling tasks.

Natural Spline

B-Spline

Curve Implementation

Developed multiple graphics demos using OpenGL, demonstrating object transformation, lighting, and rendering techniques with various mathematical frameworks.

 Object Transformation & Illumination

 Ray Tracing

Project Overview

Designed and implemented core gameplay elements in Unity 3D, including character motion, particle effects, and enemy AI behaviors.

 Character Motion

 Particle Effects

 Raid Monster AI (Raid Hunter)

Unity 3D Game Development: Motion & Particle FX Design

Project Overview

Designed a fully immersive VR gameplay experience using Unreal Engine 4, focusing on monster pattern design, level/map layout, and player-environment interaction in a virtual space.

 Monster Pattern Design

 Map / Level Design

 VR Mechanics

VR Game Design using Unreal Engine 4

Clear all dots within the time limit by strategically connecting same-colored dots.

Developed a real-time puzzle game inspired by Two Dots, where the objective is to reduce all remaining dots to zero.

Implemented core gameplay mechanics: dot matching, chain elimination, combo detection, and time-based challenge system.

Designed intuitive UI and grid system for visualizing dot connections using a custom rendering loop.

Added mission tracking, real-time countdown, and animated feedback for player actions.

Two Dots-Inspired Puzzle Game

Table

At a glance

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Teaching Assistant

Subject Name

Duration of work

Institution

Computer Graphics

2021/03/02 → 2021/06/25

Korea Univ.

2021/03/02 → 2021/06/25

Korea Univ.

Computer Colloquium

2021/03/02 → 2021/06/25

Korea Univ.

2023/08/21 → 2024/12/06

Vanderbilt Univ.

2024/01/08 → 2024/05/01

Vanderbilt Univ.

Computer Architecture

2024/08/22 → 2024/12/10

Vanderbilt Univ.

Aritificial Intelligence

2025/01/07 → 2025/05/01

Vanderbilt Univ.

Seminars (Korean)

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Position-Based Dynamics (21. 2)

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CD-MPM: continuum damage material point methods for dynamic fracture animation (21. 5)

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Revisiting Integration in the Material Point Method: A Scheme for Easier Separation and Less Dissipation (21. 9)

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A Moving Least Squares Material Point Method with Displacement Discontinuity and Two-Way Rigid Body Coupling (21. 11)

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Stormscapes: simulating cloud dynamics in the now (22. 5)

[220512]_PaperSeminar_.pdf

3074.1KB

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Simulating Fracture with Material Points (22.9)

[220901]_Paper_Seminar_Simulating Brittle Fracture.pdf

2734.8KB