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Hojun Lee

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2 papers
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2

AAAI Conference 2026 Conference Paper

Targeted Data Protection for Diffusion Model by Matching Training Trajectory

  • Hojun Lee
  • Mijin Koo
  • Yeji Song
  • Nojun Kwak

Recent advancements in diffusion models have made fine-tuning text-to-image models for personalization increasingly accessible, but have also raised significant concerns regarding unauthorized data usage and privacy infringement. Current protection methods are limited to passively degrading image quality, failing to achieve stable control. While Targeted Data Protection (TDP) offers a promising paradigm for active redirection toward user-specified target concepts, existing TDP attempts suffer from poor controllability due to snapshot-matching approaches that fail to account for complete learning dynamics. We introduce TAFAP (Trajectory Alignment via Fine-tuning with Adversarial Perturbations), the first method to successfully achieve effective TDP by controlling the entire training trajectory. Unlike snapshot-based methods whose protective influence is easily diluted as training progresses, TAFAP employs trajectory-matching inspired by dataset distillation to enforce persistent, verifiable transformations throughout fine-tuning. We validate our method through extensive experiments, demonstrating the first successful targeted transformation in diffusion models with simultaneous control over both identity and visual patterns. TAFAP significantly outperforms existing TDP attempts, achieving robust redirection toward target concepts while maintaining high image quality. This work enables verifiable safeguards and provides a new framework for controlling and tracing alterations in diffusion model outputs.

IROS Conference 2025 Conference Paper

EASEIR: Efficient and Adaptive Safe-set Estimation via Implicit Representation for High-dimensional Motion Planning

  • Hojun Lee
  • Yuseop Sim
  • Changheon Han
  • Jiho Lee
  • Aniket Bera
  • Changju Kim
  • Martin Byung-Guk Jun

Collision-free robotic manipulation is extremely important for all safety-critical applications of robots. Especially for large-scale automation in modern manufacturing facilities where numerous hardware and software systems collaborate in relatively structured environments, accomplishing effectiveness, efficiency, and safety in not only repetitive tasks but also their sporadic reconfigurations is ideal. Yet, existing online and offline Motion Planning (MP) algorithms do not meet such a unique combination of harsh demands, since most of the advances in MP aim for a subset of the requirements. To bridge the gap, we introduce a novel implicit neural function (EASEIR) designed for efficient offline safe set composition for robotic manipulators operating in structured environments. Addressing the challenges of managing high-dimensional configuration spaces (C-space), EASEIR leverages Implicit Neural Representations (INR) to relate coordinates of a discretized robot operation space with collision sets in C-space. EASEIR then utilizes the mapping to actively compose a collision-free set in response to arbitrary occupancy of the operation space by obstacles. The proposed method comprises three core modules: (a) Latent Key Generator (LKG) that maps the coordinates of the space to intermediate latent keys, (b) Latent Key Decoder (LKD) that reconstructs collision sets from the keys, and (c) Full Set Compositor (FSC) that generates a full collision-free set using set operations. On a 6 Degrees of Freedom (DoF) arm, EASEIR generates safe configuration sets nearly 43 times faster than the state-of-the-art analytical method while maintaining comparable accuracy (∼ 0. 2% collision) during evaluations in a simulation environment.

v2026.09.13