Research

Current Research Interests

The Quantum Radiation Imaging Science Lab (QRIS) in the Department of Nuclear and Quantum Engineering at KAIST investigates how ionizing radiation can be used as a quantitative probe of structure and dynamics across length scales, from engineering components to biomedical and potential clinical applications. Our group works primarily with X‑rays, developing systems that deliberately exploit both the particle nature of radiation (absorption, Compton scattering, detection statistics) and its wave nature (refraction, interference, coherent diffraction). By treating the imaging chain from source and optics to detector and reconstruction, we aim to overcome the limitations of conventional radiation imaging techniques.

Our research interests include advanced phase‑ and dark‑field X‑ray imaging, scattering tensor tomography, correlation‑based schemes such as ghost and single‑pixel imaging, and coherent diffraction imaging such as ptychography. In parallel with these imaging efforts, we also pursue projects on radiation detection and shielding, where rigorous models of radiation–matter interaction and detector response are used to design and analyze systems for radiation safety, monitoring, and nuclear materials management. Across these topics, we develop wave‑optical and Monte Carlo models, perform radiation transport and shielding simulations, build laboratory‑ and synchrotron‑based experimental setups, and design reconstruction algorithms informed by the relevant physical principles. Students joining QRIS will work at the interface of theory, computation, and hands‑on experiments on radiation detection and imaging systems.

Advanced radiation imaging and microscopy systems

We push the limits of contrast and sensitivity in X‑ray and electron microscopy to reveal structures. We try to leverage the quantum mechanical properties of radiation to surpass what conventional imaging techniques can resolve. Our group develops phase‑contrast and scattering imaging methods for micro- and nanostructured materials where absorption contrast falls short, and diffraction‑based imaging to map crystallography, strain, and defects. Experiments span compact instruments with higher accessibility and synchrotron‑based X‑ray microscopy for high‑coherence, high‑speed, and in‑situ studies. Through active collaborations with international partners, we gain exposure to world‑class facilities and international teamwork while learning how to design, execute, and validate advanced microscopy experiments.

Example topics:

Synchrotron-based X-ray imaging and microscopy
Phase contrast and dark-field imaging
High energy X-ray microscopy
X-ray laminography
Ptychography and super-resolution imaging
Ghost imaging
4D scanning transmission electron microscopy

Publications

Advanced signal retrieval and tomographic reconstruction algorithms

We couple physics‑based forward models with modern computational techniques to extract more information from measurements. Potential topics include tensor tomography to quantify orientation and anisotropy fields, deep‑learning–assisted denoising and tomography for sparse data, phase and scattering signal retrieval to unlock hidden contrast, ptychography and super‑resolution algorithms that push past hardware limits. We focus on interpretable, uncertainty‑aware reconstructions and rigorous validation against simulations and experiments. We work with both simulation and real experimental datasets, and develop advanced computational imaging techniques.

Example topics:

Tensor tomography
Deep-learning-assisted noise reduction and tomographic reconstruction
Phase and scattering retrieval algorithms
High fidelity reconstruction algorithms for sparse dataset

Publications

Radiation measurment and safeguard research

We study and innovate detectors that convert high-energy radiation into measurable signals. Using Monte Carlo simulations and accurate system‑level models, we analyze how sources, samples, and detectors govern contrast, dose efficiency, and resolution, then use these insights to propose novel elements and detector designs. Our efforts extend to radiation shielding and safeguards for nuclear facilities, translating measurement principles into practical monitoring and protection solutions. We gain experience in high-energy radiation detector physics and engineering.

Example topics:

Radiation portal monitoring systems
Monte Carlo simulation studies
Accurate modeling of ionizing radiation-based imaging systems
Novel optical elements and detector design
Radiation shielding and safeguard research in nuclear facilities

Publications

Application fields

Biomedical materials

High‑contrast phase‑contrast and/or darkfield imaging of lung, breast, bone, and teeth at clinically realistic doses
Multiscale 3D imaging to connect microstructure with organ‑scale performance

Semiconductor chips

Non‑destructive 3D inspection of advanced packaging and interconnects
Strain/defect mapping to link process conditions to reliability
Fast, low‑dose imaging pipelines for in‑line metrology

Composite materials

Orientation‑resolved tomography to map fiber alignment, linking microstructure to stiffness and strength
Quantifying hierarchical, anisotropic architectures and linking them to mechanical strength and failure

Batteries and fuel cells

Operando 3D imaging of cracks, plating, and phase changes during cycling
Quantifying pore networks and transport pathways in electrodes and membranes
Nanoscale reconstructions to study interfaces and catalyst layers

Nuclear materials

3D assessment of microcracking, swelling, and voids in irradiated alloys and fuels
Texture/strain mapping under thermal and mechanical loads
Radiation‑tolerant detectors and shielding for hot‑cell and safeguards environments