In this paper, we illustrate a method of reconstructing the size distribution of magnetic nano-particles (MNP) using a
magnetization curve that was measured on a water-based MNP. The objective was to find solutions to the ill-posed
problem in the matrix equation Ax=b, which was obtained from the numerical model on magnetization. Prior the use of
Singular Value Decomposition (SVD), a method utilizing a total of 60 sample points of magnetization curves was
obtained from Superconducting QUantum Interface Devices (SQUID) in attempts to achieve a favorable solution.
However, eliminating oscillation in this manner was proven difficult. Therefore, the Tikhonov regulation (A<sup>T</sup>A-&agr;I) was
offered in the solution to overcome the above-mentioned ill-posed problem. Size distributions from Tikhonov SVD
(TSVD) were found stable. As predicted in previous theoretical analyses, a lognormal-like distribution of the MNP could
be observed in single-origin MNP EMG1111.