Younghyun Kim

Last Year Marked the 30th anniversary of the IEEE/ACM International Symposium on Low Power Electronics and Design (ISLPED). The conference was held on August 6–8, 2025, on the University of Iceland Campus in Reykjavík, Iceland, as an in-person event. The symposium spanned 2.5 days to accommodate a large number of paper presentations and special events. The program featured three keynote speeches delivered by Dr. Michaela Blott (AMD), Prof. Kenichi Okada (Institute of Science Tokyo, Japan), and Dr. Brucek Khailany (Nvidia), along with two panel discussions, two special sessions, two tutorials, 39 regular paper presentations, 21 poster presentations, and a design contest showcasing four demos. The symposium attracted 131 attendees from 16 countries.

Federated learning (FL) has been increasingly widely used for distributed and privacy-preserving machine learning (ML) environments, as the raw training data can stay local to clients while leveraging model updates from individual clients. Homomorphic encryption (HE) technologies can provide additional privacy protection for FL by encrypting the model update parameters while allowing model aggregation on a remote server. Although HE-enabled FL seems to be a promising privacy-preserving ML solution, it requires significantly more computational and memory resources, requiring a dedicated hardware and software platform. In this paper, we discuss preliminary but concrete and realizable research ideas for analyzing the requirements for HE-enabled FL and for designing a hardware and software platform. Furthermore, we propose a platform co-design process that considers various design stages and challenges in the platform co-design.

Trust in digital systems depends on secure hardware, often assured through HRE. This work develops methods for investigating human problem-solving processes in HRE, an underexplored yet critical aspect. Since reverse engineers rely heavily on visual information, eye tracking holds promise for studying their cognitive processes. To gain further insights, we additionally employ verbal thought protocols during and immediately after HRE tasks: Concurrent and Retrospective Think Aloud. We evaluate the combination of eye tracking and Think Aloud with 41 participants in an HRE simulation. Eye tracking accurately identifies fixations on individual circuit elements and highlights critical components. Based on two use cases, we demonstrate that eye tracking and Think Aloud can complement each other to improve data quality. Our methodological insights can inform future studies in HRE, a specific setting of human-computer interaction, and in other problem-solving settings involving misleading or missing information.

Users embrace the rapid development of virtual reality (VR) technology for everyday settings. These settings include payment, which makes user authentication necessary. Despite this need, there is a limited understanding of how users' unique experiences in VR contribute to their security perception. To understand this question, we designed probes of payment authentication, which are embedded in the routine payment of a VR game, to provoke participants' reactions from multiple angles.

Heat stress, caused by a warming climate and the increasingly high milk-producing dairy cattle, is one of the major threats to the well-being of dairy cattle as well as the economic, environmental, and social sustainability of dairy farming around the world. Timely identification of cows under heat stress is crucial to improving animal welfare, preventing milk production losses, and preserving water and energy for cooling. This paper presents a smart ear tag, named eTag, and an associated system that can read a passive microchip temperature sensor subcutaneously injected into the animal with minimal discomfort. It features a lightweight design using a single coil shared for microchip scanning and wireless charging. eTag is autonomously recharged by a wireless charger over the head during daily milking sessions, enabling perpetual operation without battery replacement after deployment. The real-world performance of the proposed system was examined intensively in a three-week deployment on seven lactating Holstein cows. We demonstrate that eTag can reliably collect accurate body temperature in real time while maintaining a positive energy flow. The deployment of eTag will enable the timely detection of heat stress and facilitate precision control of barn cooling systems.

Users readily embrace the rapid advancements in virtual reality (VR) technology within various everyday contexts, such as gaming, social interactions, shopping, and commerce. In order to facilitate transactions and payments, VR systems require access to sensitive user data and assets, which consequently necessitates user authentication. However, there exists a limited understanding regarding how users' unique experiences in VR contribute to their perception of security. In our study, we adopt a research approach known as ``technology probe'' to investigate this question. Specifically, we have designed probes that explore the authentication process in VR, aiming to elicit responses from participants from multiple perspectives. These probes were seamlessly integrated into the routine payment system of a VR game, thereby establishing an organic study environment. Through qualitative analysis, we uncover the interplay between participants' interaction experiences and their security perception. Remarkably, despite encountering unique challenges in usability during VR interactions, our participants found the intuitive virtualized authentication process beneficial and thoroughly enjoyed the immersive nature of VR. Furthermore, we observe how these interaction experiences influence participants' ability to transfer their pre-existing understanding of authentication into VR, resulting in a discrepancy in perceived security. Moreover, we identify users' conflicting expectations, encompassing their desire for an enjoyable VR experience alongside the assurance of secure VR authentication. Building upon our findings, we propose recommendations aimed at addressing these expectations and alleviating potential conflicts.