HJJ

About Me

Senior undergraduate at KAIST (School of Computing & Nuclear and Quantum Engineering), interested in computer architecture, systems software, and hardware–software co-design.

Research Interests

  • Memory Hierarchy & RTL-Level Design: architectural exploration of memory hierarchy design with interest in RTL-level hardware component development.
  • CXL-Based Disaggregated Memory: interest in memory-pressure-driven smart routing in CXL-based disaggregated memory systems and hardware/software co-design.
  • Distributed ML State Management: seamless resumption of distributed ML training through consistent multi-process state capture (RNG, optimizer, data loader state).

Preprints

SHIFT: Sigmoid-Based Heuristic Invertible Fitness-Landscape Transformation

2025

Jeongjin Han, Seunghoon Sim, Jian Lee, Seongyoon Park — First author

arXiv:2604.09171

VRAIL: Vectorized Reward-based Attribution for Interpretable Learning

2025

Co-author (equal contribution)

arXiv:2506.16014

Research Experience

Nuclear I&C and Autonomous Operation Lab, KAIST

Winter 2025

Undergraduate Researcher — Advisor: Prof. Jonghyun Kim

  • Identified system-level bottlenecks under memory and bandwidth constraints across heterogeneous CPU–GPU pipelines.
  • Led pipeline redesign to resolve a GPU underutilization bottleneck caused by a CPU-bound simulator; decoupled policy optimization from environment interaction, improving hardware utilization.
  • Reverse-engineered the process memory layout of a closed-source Windows VM simulator to extract and inject runtime state variables, enabling system integration without source access or binary modification.
  • Designed and implemented a TCP/Docker-based distributed execution infrastructure bridging a Windows VM and a GPU server, managing cross-system state synchronization under memory bandwidth and latency constraints.

Reactor Physics and Transmutation Lab, KAIST

Winter 2024

Undergraduate Researcher — Advisor: Prof. Yonghee Kim

  • Conducted Monte Carlo neutron transport simulations using OpenMC, analyzing neutron moderation behavior under Thermal Scattering Law (TSL) models from the ENDF/B-VIII.1 nuclear data library.
  • Investigated computational and memory characteristics of large-scale Monte Carlo simulation workloads, and analyzed scalability behavior under parallel execution.

Tech Stack

Languages

C++RustPythonMATLABScalaVerilog

Tools & Frameworks

PyTorchgem5DockerHuggingFaceLaTeXGitLinux