• Journal of Power Electronics
• /
• v.9 no.2
• /
• pp.180-187
• /
• 2009

When converters operate in megahertz range, the passive components and magnetic devices generate high losses. However, the eddy current issues and choices of magnetic cores significantly affect on the design stage. Apart from that, the components' reduction, miniaturization technique and frequency scaling are required as well as improvement in thermal capability, integration technique, circuit topologies and PCB layout optimization. In transformer design, the winding and core losses give great attention to the design stage. From simulation work, it is found that E-25066 material manufactured by AVX could be the most suitable core for high frequency transformer design. By employing planar geometry topology, the material can generate significant power loss savings of more than 67% compared to other materials studied in this work. Furthermore, young researchers can use this information to develop new approaches based on concepts, issues and methodology in the design of magnetic components for high frequency applications.

• Journal of Magnetics
• /
• v.20 no.1
• /
• pp.86-90
• /
• 2015

Electromagnetic actuators are versatile and able to meet demanding requirements, such as operation in very low or very high temperatures. When the actuator is used in a high-temperature environment up to $500^{\circ}C$, we need to know how the force-producing capability of the actuator is affected by the operating temperature. Specifically, it is necessary to know the temperature-dependence of magnetic properties that determine the mechanical forces. In this paper, we measure the changes in magnetic properties of SUS410 material in high-temperature environment. We also devise a novel signal processing technique to remove the integration drift. At the field strength of 18,000 A/m, we found that the flux density at $500^{\circ}C$ is decreased by 26%, compared to the result at room temperature. Therefore, the actuator must be sized appropriately, if it is to operate in high-temperature settings.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.52 no.9
• /
• pp.427-433
• /
• 2003

Permanent magnet movers with three different magnetization patterns were applied to a linear eddy current braking system. By using a two-dimensional analytical technique, this paper deals with the comparison of the design guidelines, magnetic field, required magnet volume, and force capability for three types of linear brakes. The analytical results are also verified by finite element analyses.

• Journal of the Korean Society for Railway
• /
• v.19 no.2
• /
• pp.117-123
• /
• 2016

High speed circuit breakers(HSCB) interrupt the generated arc within the arc chute to turn off the electricity flowing through the main circuit to prevent ground faults. In order to explore the arc generated from the contactor operation, arc definition, establishment of arc interruption method, and analysis of magnetic driving force are required. In this paper, arc interruption capability has been estimated by exploring the difference in magnetic flux density of Lorenz forces using finite element analysis. In addition, since the number of grids and changes in the grid shape within the arc chute influence the formation of the inner magnetic field, its effects have been explored to enhance arc interruption capability. Assessment of interruption capability and analysis of grid shape, with rated operating current, are reported.

• Journal of the Korean Magnetics Society
• /
• v.24 no.4
• /
• pp.114-122
• /
• 2014

Since 1990, Agency for Defense Development (ADD) has been operating the nonmagnetic laboratory and the magnetic sensors laboratory to develop the key technology of the ship's magnetic silencing and to research the high performance magnetic sensors used in the weapon system and to perform the technical support for Republic of Korea Navy. Recently, the main test equipment in the laboratories has been upgraded to improve the measurement and analysis abilities against magnetic target and to evaluate the performance of the magnetic sensors. In this paper, the capability and the current state of magnetic test facilities of ADD are described.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.10 no.2
• /
• pp.79-83
• /
• 2011

Magnetic seal uses a magnetic fluid to seal a gap between a rotating shaft and housing. It is distinguished from other kinds of seals from the fact that solid contact does not occur in the seal. This implies that it is free from solid rubbing thus dustless and provides a clean circumstance. That is the reason why the magnetic seal is used exclusively for most of vacuum chambers in semiconductor process where dustless clean circumstance is critical. A magnetic seal has been developed of which design parameters are determined based on published data, and an air pressure test has been done to examine its sealing capability. Effects of some design parameters have been studied through FEM analysis. The results show some notable aspects of design parameters and provide suggestions for developing the seals. Regarding the sealing capacity of the magnetic seal the factor to match the theoretical value with the actual one was found to be 0.4~0.7, which means still there is some discrepancy between theory and actual.

• Proceedings of the Korean Magnestics Society Conference
• /
• 2000.09a
• /
• pp.532-538
• /
• 2000

A double rectangular spiral inductor is fabricated using FeTaN films. The inductor is composed of internal coils sandwiched by magnetic layers. Characteristics of inductor performance are investigated with an emphasis on planarization of magnetic films. In the absence of the planarization process, the grating topology of upper magnetic films over coil arrays degrades the soft magnetic properties and the inductor performance. It also induces a longitudinal magnetic anisotropy with the easy axis aligned to the magnetic flux direction. This alignment prevents the upper magnetic films from contributing to the total induction. Glass bonding is a viable method for achieving a completely planar inductor structure. The planar inductor with glass bonding shows excellent performance : inductance of 1.1 H, Q factor of 7 (at 5 MHz), and the dc current capability up to 100 mA.

• Proceedings of the KIEE Conference
• /
• 2002.11c
• /
• pp.278-281
• /
• 2002

In this paper we propose a controller which has the capability of disturbance measurement calibration for Cds array sensors in a magnetic levitation system. Steady state error due to environment light condition or external disturbance is corrected constantly. The correction is made by the sensors to measure the ball position of the system without additional deployment of sensors.

• Proceedings of the KIEE Conference
• /
• 2002.11d
• /
• pp.36-38
• /
• 2002

Low voltage circuit breakers which interrupt rapidly and raise the reliability of power supply are widly used in power distribution systems. In the paper, it was investigated how much Interrupting capability was improved by correcting the shape of the contact system in molded case circuit breaker(below MCCB), Prior to the interrupting testing, it was necessary for the optimum design to analyze magnetic forces on the contact system, generated by current and flux density. This paper presents both our compuational analysis and test results contact system in MCCB.

• Proceedings of the KIEE Conference
• /
• 2001.04a
• /
• pp.353-356
• /
• 2001

This paper describes an analysis of electromagnetic system of Magnetic Switch using 3D and 2D finite element method. The electromagnetic blowout force acting on the arc is obtained by 3D finite element method. So, we are researching the arc chamber for dc current using permanent magnet.