By employing soft X-ray absorption spectroscopy (XAS) and soft X-ray magnetic circular dichroism (XMCD), the electronic structures of Li_0.5FeCr_1.5O₄ spinel ferrite have been investigated, which exhibits the negative magnetization phenomenon. It is found that that both Fe and Cr ions are trivalent, that most of Fe³⁺ ions occupy the A (T_d) sites while Cr³⁺ ions occupy the B (O_h) sites, and that the magnetic moments of Fe ions and those of Cr ions are coupled antiferromagnetically to each other. Hence Li_0.5FeCr_1.5O₄ can be represented as (Fe)_A[Li_0.5Cr_1.5]_BO₄.

This paper reports the optimize of solenoid coil in the coil gun by adjusting the winding number of coil and the distance between coil and projectile, and the performance of the coil gun was improved by using the method of operating the SCR switch with the physical contact of the projectile to flow the current to the two-stage coil. In the coil gun, the velocity of the projectile is influenced by several factors. Cycle changes according to the capacity of capacitor, the winding of the solenoid coil and diameter of wire. Distance between projectile and coil also influences the final velocity during capacitor discharge. When projectile passes a certain part of the coil, receives the force in the reverse direction due to the Suction phenomenon and the speed decreases. Therefore, in order for the projectile to have the optimal speed, it is necessary to combine the above elements to find the optimal value. It is also important to control the discharge time of the solenoid coil when making the multi stage coil. The discharge method applied in this research has a simple circuit configuration than the previous method using a sensor, and the speed loss is less than the physical contact method of the general switch because the torque required for the switch operation is low, and It has the advantage that the coil gun system using the high voltage can be operated stably. The velocity of the projectile was calculated using Maxwell, an electromagnetic analysis program, and based on this, a prototype for coil gun and SCR discharge circuit was produced to measure the velocity of the projectile.

In this paper, we propose a new type of current sensor suitable for miniaturization and high-frequency current measurement. The current sensor is fabricated using a cylindrical ferrite core and two permanent magnets attached to both ends of the ferrite core. The operation principle was explained using the FEM analysis results and the magnetization motion inside the ferrite core. To check the current measurement performance of the fabricated current sensor, the output voltage was measured while changing the amplitude of the alternating current from 0 to 10 A at 10 kHz. Although the output signal was not linear with respect to the current, it was very well matched with the regression curve showing that the proposed current sensor can be used as a current sensor in the tens of kHz band.

In this paper, we report the results of investigating the effect of a magnetic field on the resonance frequencies of a sensor array composed of three LC resonance elements. An LC resonator was fabricated using a ceramic capacitor and an inductor fabricated with a Ni-Zn ferrite core. Three LC resonators were connected in parallel to form a simple sensor array. The change in resonance frequency was observed while applying a magnetic field to each LC resonance element. Since the resonance frequency of each LC resonance element is different to others, even if the resonance frequency of an individual resonance element changes due to a magnetic field, there is no change in the resonance frequencies of other adjacent resonance elements. Therefore, when constructing a sensor array using LC resonant elements in the manner proposed in this paper, it was found that multiple sensor signals can be acquired with only a pair of wires.

Magnetic nanoparticles have not only been required for biological DNA isolation, detection and purification, but also have been studied steadily until recently as medical chemical processing materials for drug delivery and release that can control cancer cells in the human body. Using a ion selective field effect transistor (ISFET) pH sensor, a pH value sensitive to the concentration of hydrogen ions (H⁺) dissolved in various liquid solutions was measured according to the behavior of magnetic nanoparticles in the external magnetic field. The magnetic nanoparticle solution of pH 7.1 was mixed with acidic, neutral, and alkaline buffer solution at a ratio of 3:1, and the acidic solution having a pH of 3.9 with respect to the change of magnetic particle distribution was found to have a change of 35 mV (0.65 pH), which is greater than the pH of the alkaline solution of pH 9.8. Some of the H⁺-ions in the solution was bound to the magnetic nanoparticles and the concentration of ions was reduced near the Si₃N₄ layer of the ion sensitive membrane, so that the change in pH value, the output voltage, was closely related to the distribution of the nanoparticles. The output voltage curves between the two terminal source and drain for the external magnetic field were symmetrical around 0 Oe, and the variation up to ±1000 Oe was greater in acidic solutions than alkaline. Because a multi-reactive polymer nanoparticles containing drugs with a pH of about 7.2 for treatment of cancer cells with a pH of 6.8 move to targets, we suggest the therapy system in which the ring of nanoparticles is decomposed by high-frequency magnetic field therapy.