The main research area is sampling theories in various functional spaces. Recently he has a strong interest in irregular sampling theories in shift-invariant spaces(SIS), average sampling series in SIS, vector sampling theories in SIS, channeled sampling theories in SIS and its aliasing errors. He is interested in not only sampling theories in SIS but also ones in Wavelet sub-spaces and reproducing kernel Hilbert spaces. Multi-resolution analysis and harmonic analysis are research interests as well.