Youyeon Joo
Ph.D. student

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Education
  • Seoul National University
    Seoul National University
    Department of Electrical and Computer Engineering
    Ph.D. Student (Advisor: Yunheung Paek)
    Mar. 2022 - present
  • Ewha Womans University
    Ewha Womans University
    B.S. in Cyber Security (Cum Laude)
    Mar. 2018 - Feb. 2022
Experience
  • Yale University
    Yale University
    Visiting student
    Jun. 2023 - Jul. 2023
Honors & Awards
  • Excellence Paper Award of ACK 2024 (granted by KIPS)
    2024
  • Excellence Paper Award of ASK 2023 (granted by KIPS)
    2023
  • Academic Excellence Scholarship (granted by Ewha Womans University)
    2020-2022
News
2026
"HEPIC: Private Inference over Homomorphic Encryption with Client Intervention" is accepted to ASPLOS 2026.
Mar 22
2025
"An Accelerator for low-computational overhead Privacy-Preserving GNN Inference" is accepted to HiPC 2025.
Sep 12
"Efficient Keyset Design for Neural Networks Using Homomorphic Encryption" is accepted to MDPI Sensors.
Jul 08
"SLOTHE : Lazy Approximation of Non-Arithmetic Neural Network Functions over Encrypted Data" is accepted to USENIX Security 2025.
Jun 06
Homepage is created !
Jun 05
Selected Publications (view all )
HEPIC: Private Inference over Homomorphic Encryption with Client Intervention

Kevin Nam, Youyeon Joo, Seungjin Ha, Hyungon Moon$\dagger$, Yunheung Paek$\dagger$ ($\dagger$ corresponding author)

ACM International Conference on Architectural Support for Programming Languages and Operating Systems (ASPLOS), 2026

Recent HE-based Private Inference (PI) systems improve the accuracy--performance trade-off via a layer-wise scheme and parameter switching, yet remain bottlenecked by fire-and-forget execution in which the server alone performs costly ciphertext management. This paper presents HEPIC, an HE-based PI system that explores a different design point by leveraging client interventions for ciphertext managements.

HEPIC: Private Inference over Homomorphic Encryption with Client Intervention

Kevin Nam, Youyeon Joo, Seungjin Ha, Hyungon Moon$\dagger$, Yunheung Paek$\dagger$ ($\dagger$ corresponding author)

2026

Recent HE-based Private Inference (PI) systems improve the accuracy--performance trade-off via a layer-wise scheme and parameter switching, yet remain bottlenecked by fire-and-forget execution in which the server alone performs costly ciphertext management. This paper presents HEPIC, an HE-based PI system that explores a different design point by leveraging client interventions for ciphertext managements.

SLOTHE : Lazy Approximation of Non-Arithmetic Neural Network Functions over Encrypted Data

Kevin Nam*, Youyeon Joo*, Seungjin Ha, Yunheung Paek$\dagger$ (* equal contribution, $\dagger$ corresponding author)

USENIX Security Symposium (USENIX Sec), 2025

Existing works adopt an eager approximation (EA) strategy to approximate non-arithmetic functions (NAFs), which statically replaces each NAF with a fixed polynomial, locking in computational errors and limiting optimization opportunities. We propose SLOTHE, a lazy approximation (LA) solution that recursively decomposes NAF codes into arithmetic and nonarithmetic sub-functions, selectively approximating only the non-arithmetic components when required.

SLOTHE : Lazy Approximation of Non-Arithmetic Neural Network Functions over Encrypted Data

Kevin Nam*, Youyeon Joo*, Seungjin Ha, Yunheung Paek$\dagger$ (* equal contribution, $\dagger$ corresponding author)

2025

Existing works adopt an eager approximation (EA) strategy to approximate non-arithmetic functions (NAFs), which statically replaces each NAF with a fixed polynomial, locking in computational errors and limiting optimization opportunities. We propose SLOTHE, a lazy approximation (LA) solution that recursively decomposes NAF codes into arithmetic and nonarithmetic sub-functions, selectively approximating only the non-arithmetic components when required.

All publications