Masaaki Kondo

Masaaki Kondo

*This is an algorithmically generated author record based on publicly available information.

Current Organizations / Institutes

The organizations/institutes from the scholar's latest article

Previous Organizations / Institutes

The organizations / institutes from the scholar's other articles in the past ten years


Masaaki Kondo has a total of 37 co-authors. Here are the top co-authors by number of shared publications:


Latest Publications

  • Open Access

    InstantFT: A Field-Programmable Gate Array-Based Runtime Subsecond Fine-Tuning of Convolutional Neural Network Models

    by Keisuke Sugiura, Masaaki Kondo, Radu Marculescu, Hiroki Matsutani

    In edge machine learning (EdgeML) applications, pre-trained deep neural networks (DNNs) often suffer from suboptimal performance due to the gap between the data used for pre-training and that observed in the deployed environment. This necessitates an efficient on-device fine-tuning algorithm to quickly adapt to changing data distributions and maintain high prediction accuracy. In this paper, we propose InstantFT, an adapter-based parameter-efficient fine-tuning (PEFT) method for CNNs, along with its accelerator targeting Xilinx Kria FPGAs. InstantFT adopts low-rank adapters with skip-connections to minimize backpropagation cost, improve parallelism, and enable caching and reuse of intermediate activations. Experiments demonstrate that InstantFT fine-tunes lightweight CNNs 17.4x faster than existing Low-Rank Adaptation (LoRA) methods while maintaining comparable accuracy under distribution shifts. Our FPGA-based accelerator brings down the fine-tuning time to just 0.36s, enabling on-the-fly adaptation of deployed models to non-stationary data distributions.

  • Open Access

    D2-LoRA: A Synergistic Approach to Differential and Directional Low-Rank Adaptation

    by Nozomu Fujisawa, Masaaki Kondo

    We systematically investigate the parameter-efficient fine-tuning design space under practical data and compute constraints, and propose D2-LoRA. D2-LoRA achieves 76.4 percent average accuracy across eight question answering and reading comprehension benchmarks using only 5k training samples per task and two epochs, while preserving algebraic mergeability at inference with near-exact numerical equivalence. The method combines signed low-rank residual updates with additive and subtractive components, together with a train-time column-wise projection that keeps each column close to its original norm. After training, the adapter is merged into a single weight matrix, adding zero inference latency. Compared with LoRA, D2-LoRA improves average accuracy by 2.2 percentage points; at matched parameter counts (LoRA rank 2r versus D2-LoRA rank r), the improvement is 1.6 points, indicating gains from architectural design rather than increased parameterization. Compared with DoRA, it matches or exceeds performance on most tasks. Beyond QA and reading comprehension, D2-LoRA improves generative tasks (plus 1.2 ROUGE-L and plus 1.1 percent win rate) and shows 36 percent lower training volatility. The merge preserves numerical fidelity (mean gap about 0.03 percentage points) and recovers about 1.91x evaluation throughput. Training overhead is 19 percent, comparable to DoRA, and decreases with longer input sequences. We provide a geometric analysis explaining how the projection stabilizes training, together with ablation studies isolating the contribution of each design component.

  • Open Access

    Quantum framework for reinforcement learning: Integrating the Markov decision process, quantum arithmetic, and trajectory search

    by Thet Htar Su, Shaswot Shresthamali, Masaaki Kondo

    This paper introduces a quantum framework for addressing reinforcement learning (RL) tasks, grounded in the quantum principles and leveraging a fully quantum model of the classical Markov decision process. By employing quantum concepts and a quantum search algorithm, this work presents the implementation and optimization of the agent-environment interactions entirely within the quantum domain, eliminating reliance on classical computations. Key contributions include the quantum-based state transitions, return calculation, and trajectory search mechanism that utilize quantum principles to demonstrate the realization of RL processes through quantum phenomena. The implementation emphasizes the fundamental role of quantum superposition in enhancing computational efficiency for RL tasks. Results demonstrate the capacity of a quantum model to achieve quantum enhancement in RL, highlighting the potential of fully quantum implementations in decision-making tasks. This work not only underscores the applicability of quantum computing in machine learning but also contributes to the field of quantum reinforcement learning by offering a robust framework for understanding and exploiting quantum computing in RL systems. Published by the American Physical Society 2025


  • Open Access

    Q-Gen: A Parameterized Quantum Circuit Generator

    by Yikai Mao, Shaswot Shresthamali, Masaaki Kondo

    Unlike most classical algorithms that take an input and give the solution directly as an output, quantum algorithms produce a quantum circuit that works as an indirect solution to computationally hard problems. In the full quantum computing workflow, most data processing remains in the classical domain except for running the quantum circuit in the quantum processor. This leaves massive opportunities for classical automation and optimization toward future utilization of quantum computing. We kickstart the first step in this direction by introducing Q-gen, a high-level, parameterized quantum circuit generator incorporating 15 realistic quantum algorithms. Each customized generation function comes with algorithmspecific parameters beyond the number of qubits, providing a large generation volume with high circuit variability. To demonstrate the functionality of Q-gen, we organize the algorithms into 5 hierarchical systems and generate a quantum circuit dataset accompanied by their measurement histograms and state vectors. This dataset enables researchers to statistically analyze the structure, complexity, and performance of large-scale quantum circuits, or quickly train novel machine learning models without worrying about the exponentially growing simulation time. Q-gen is an open-source and multipurpose project that serves as the entrance for users with a classical computer science background to dive into the world of quantum computing.


  • Open Access

    Skip2-LoRA: A Lightweight On-device DNN Fine-tuning Method for Low-cost Edge Devices

    by Hiroki Matsutani, Masaaki Kondo, Kazuki Sunaga, Radu Marculescu

    This paper proposes Skip2-LoRA as a lightweight fine-tuning method for deep neural networks to address the gap between pre-trained and deployed models. In our approach, trainable LoRA (low-rank adaptation) adapters are inserted between the last layer and every other layer to enhance the network expressive power while keeping the backward computation cost low. This architecture is well-suited to cache intermediate computation results of the forward pass and then can skip the forward computation of seen samples as training epochs progress. We implemented the combination of the proposed architecture and cache, denoted as Skip2-LoRA, and tested it on a $15 single board computer. Our results show that Skip2-LoRA reduces the fine-tuning time by 90.0% on average compared to the counterpart that has the same number of trainable parameters while preserving the accuracy, while taking only a few seconds on the microcontroller board.


  • Open Access

    DAISM: Digital Approximate In-SRAM Multiplier-based Accelerator for DNN Training and Inference

    by Lorenzo Sonnino, Shaswot Shresthamali, Yuan He, Masaaki Kondo

    DNNs are widely used but face significant computational costs due to matrix multiplications, especially from data movement between the memory and processing units. One promising approach is therefore Processing-in-Memory as it greatly reduces this overhead. However, most PIM solutions rely either on novel memory technologies that have yet to mature or bit-serial computations that have significant performance overhead and scalability issues. Our work proposes an in-SRAM digital multiplier, that uses a conventional memory to perform bit-parallel computations, leveraging multiple wordlines activation. We then introduce DAISM, an architecture leveraging this multiplier, which achieves up to two orders of magnitude higher area efficiency compared to the SOTA counterparts, with competitive energy efficiency.

  • Open Access

    Addressing Gap between Training Data and Deployed Environment by On-Device Learning

    by Kazuki Sunaga, Masaaki Kondo, Hiroki Matsutani

    The accuracy of tinyML applications is often affected by various environmental factors, such as noises, location/calibration of sensors, and time-related changes. This article introduces a neural network based on-device learning (ODL) approach to address this issue by retraining in deployed environments. Our approach relies on semi-supervised sequential training of multiple neural networks tailored for low-end edge devices. This article introduces its algorithm and implementation on wireless sensor nodes consisting of a Raspberry Pi Pico and low-power wireless module. Experiments using vibration patterns of rotating machines demonstrate that retraining by ODL improves anomaly detection accuracy compared with a prediction-only deep neural network in a noisy environment. The results also show that the ODL approach can save communication cost and energy consumption for battery-powered Internet of Things devices.

  • Enhancing Deep Reinforcement Learning with Compressed Sensing-based State Estimation

    by Shaswot Shresthamali, Masaaki Kondo

    In various real-world applications, sensor data collected for adaptive control using Reinforcement Learning (RL) often suffer from missing information due to sensor failures, data transmission errors, or other sources of noise. Such missing data can significantly hinder the agent’s ability to make informed decisions and degrade performance. In this paper, we propose a novel approach to address this challenge by leveraging Compressed Sensing (CS) techniques to recover missing information from the sensor data and reconstruct the state observation. The reconstructed state is then fed to the RL agents. As a result, they exhibit enhanced robustness and intelligence, surpassing the performance achievable when solely presented with noisy data as state input.

  • Open Access

    Adaptive Lossy Data Compression Extended Architecture for Memory Bandwidth Conservation in SpMV

    by Siyi Hu, Makiko Ito, Takahide Yoshikawa, Yuan He, Hiroshi Nakamura, Masaaki Kondo

    Widely adopted by machine learning and graph processing applications nowadays, sparse matrix-Vector multiplication (SpMV) is a very popular algorithm in linear algebra. This is especially the case for fully-connected MLP layers, which dominate many SpMV computations and play a substantial role in diverse services. As a consequence, a large fraction of data center cycles is spent on SpMV kernels. Meanwhile, despite having efficient storage options against sparsity (such as CSR or CSC), SpMV kernels still suffer from the problem of limited memory bandwidth during data transferring because of the memory hierarchy of modern computing systems. In more detail, we find that both integer and floating-point data used in SpMV kernels are handled plainly without any necessary pre-processing. Therefore, we believe bandwidth conservation techniques, such as data compression, may dramatically help SpMV kernels when data is transferred between the main memory and the Last Level Cache (LLC). Furthermore, we also observe that convergence conditions in some typical scientific computation benchmarks (based on SpMV kernels) will not be degraded when adopting lower precision floating-point data. Based on these findings, in this work, we propose a simple yet effective data compression scheme that can be extended to general purpose computing architectures or HPC systems preferably. When it is adopted, a best-case speedup of 1.92x is made. Besides, evaluations with both the CG kernel and the PageRank algorithm indicate that our proposal introduces negligible overhead on both the convergence speed and the accuracy of final results.