Structural and magnetic properties of Ni-Zn ferrites, Ni_xZn_1−xFe₂O₄ (x = 0.2, 0.25, 0.3, 0.35, 0.4, 0.6, 0.8) prepared by solid-state-reaction process were investigated. Single cubic spinel phase were confirmed by X-ray diffraction (XRD) analysis for all the samples. Although no clear dependence of x on the microstructure were found, the magnetic properties significantly varied with x. Paramagnetic behaviors shown in the samples of x ≤ 0.25 changed to ferromagnetic behaviors with increasing x (x ≥ 0.3). The saturation magnetization (M_S) increased up to the highest value of 78.3 emu/g at x = 0.6 and then turned to decrease at x = 0.8. The complex permeability spectra (1 MHz ≤ 1 GHz) of the samples (x ≥ 0.3) shifted to high frequency direction with increasing x in accordance with Snoek’s law. This is mainly due to the increase of ferromagnetic resonance frequency induced by the increase of crystalline anisotropy.

The CoSm magnetic layer with a thickness of 30 nm was grown at a pressure of 20 mTorr on the Cr underlayer prepared with different Ar sputtering pressures. The effect of underlayer deposition conditions on magnetic interaction mechanism and magnetization reversal phenomenon was investigated. The Henkel plot, IFF and ΔM obtained from measurement curves showed that the dipole interaction was dominant in all samples, but the strength of the dipole interaction decreased with increasing sputtering pressure. In addition, all samples were found to be the dominant reversal phenomenon of the domain wall motion controlled by the domain wall pinning.

Clinical trials were performed to obtain the systolic blood pressure (SBP) dependent on the systolic time (S.time) of the radial artery wave measured by the wrist wearable pulsimeter equipped with a magnetic Hall device. One 20-year-old male and one 20-year-old female with normal blood pressure showed no significant changes in body mass index, systolic blood pressure, diastolic blood pressure, and pulse rate for 1 month. A linear regression analysis result was used to derive the blood pressure estimates obtained by using the program as a result of correlation between artificially elevated SBP and S.time measured by the clip-type pulsimeter in two 20-year-old male and female. It was confirmed that S.time of the radial artery wave was linearly and effectively decreased when the SBP was increased. Therefore, we showed the possibility of developing a personalized health care pulsimeter and blood pressure monitor which can obtain SBP according to changes of S.time measured by pulsimeter using a magnetic Hall device.

For displaying the connectome of primo vasculature system (so called kyungrak circulatory system) of rabbit, the steady mixture solution of alcian blue with the fluid of fluorescent nano-magnetic particles was injected the lymph node in the neighbor the vena cava of a rabbit. After the mixed staining fluid had been injected into the lymph node, the color of the primo vessel inside the lymph vessel presented to a dark-green-blue one. We confirmed the presence of primo vessel floating inside the lymph vessel and observed the magnetic properties by using the periodic motion of the primo vessel according to the horizontal movement of a permanent magnet in vitro status. The attractive curvature of one isolated primo vessel depended on the intensity of magnetic field passed through inside of primo vessel that had adsorbed the alcian blue and fluorescent nano-magnetic particles.

The Anhysteretic deperm protocol has many benefits for decrease of the permanent magnetization for Korean naval vessels, for example, the simplicity of its procedure, short treatment time, and the creation of permanent vertical magnetization. However, the permanent vertical magnetization created by Anhysteretic deperm protocol suffers from low magnetic stability. On the other hand, the Flash-D protocol shows higher magnetic stability compared to Anhysteretic deperm protocol but it is complex and requires long treatment time. In this paper, a Flash-KD protocol which omitted the second stage of Flash-D protocol was used to deperm a scaled model submarine. The experiment showed that the stability of magnetization created by the Flash-KD protocol is similar to that of Flash-D protocol, while it is superior compared to that of Anhysteretic deperm protocol. Further investigation will be followed to apply the Flash-KD protocol to Korean naval vessels.

There is the Flash-D demagnetization method as conventional demagnetization method for a naval ship without a degaussing system. It is the method for reducing magnetic fields from the ship as obtained the reverse permanent vertical magnetization (PVM) that counteracts the induced vertical magnetization (IVM) in the target ship due to the earth’s magnetic field. However, it is a little difficult to use in a real ship because it involves three-stage protocol and the procedure is also very complex. Therefore, in this paper, we propose the Flash-KD demagnetization method configured with two-stage demagnetization protocol for enhancing the difficulty in a practice of the conventional Flash-D demagnetization method. In the first stage of Flash-KD method, we obtain a very strong PVM. In the second stage, we gain the wanted PVM for compensating the IVM with minimization of a permanent longitudinal magnetization as adjusting the value of a horizontal start field and the total applied field number of the second stage. The proposed method has been applied to a scaled model ship to verify the performance. As a result of that, we could determine successfully the protocol which can remove VM.