• Journal of international Conference on Electrical Machines and Systems
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• 제2권3호
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• pp.295-299
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• 2013

This paper presents the new structure of a spindle motor for hard disk drive (HDD). It can produce axial force as well as torque without a pulling plate or a pulling magnet required for the normal operation of a hydrodynamic bearing in rotating-shaft structure. The proposed models have different air gap length along the axial direction by changing the thickness of permanent magnet (PM). One has a single slope and the other has double slopes on the surface of PM. For the design of the proposed models, variables are defined and its effects on the motor performances are investigated by 3-demensional finite element analysis (FEA). The equi-performance curves are investigated for the main characteristics of the spindle motor such as generated torque, axial force and torque ripple ratio. The validity of the proposed models is verified by the feasibility study and performance evaluation.

• Journal of Magnetics
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• 제16권3호
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• pp.263-267
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• 2011

The present paper proposes a novel cableless magnetic actuator with a new propulsion module that exhibits a very high thrusting force. This actuator contains an electrical inverter that directly transforms DC from button batteries into AC. The electrical DC-AC inverter incorporates a mass-spring system, a reed switch, and a curved permanent magnet that switches under an electromagnetic force. The actuator is moved by the inertial force of the mass-spring system due to mechanical resonance energy. The experimental results show that the actuator is able to move upward at a speed of 33 mm/s when using 10 button batteries when pulling a 10 g load mass. This cableless magnetic actuator has several possible applications, including narrow-pipe inspection and maintenance.

• Current Photovoltaic Research
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• 제4권3호
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• pp.124-129
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• 2016

Recently industry has voiced a need for optimally designing the production process of low-cost, high-quality ingots by improving productivity and reducing production costs with the Czochralski process. Crystalline defect control is important for the production of high-quality ingots. Also oxygen is one of the most important impurities that influence crystalline defects in single crystals. Oxygen is dissolved into the silicon melt from the silica crucible and incorporated into the crystalline a far larger amount than other additives or impurities. Then it is eluted during the cooling process, there by causing various defect. Excessive quantities of oxygen degrade the quality of silicone. However an appropriate amount of oxygen can be beneficial. because it eliminates metallic impurities within the silicone. Therefore, when growing crystals, an attempt should be made not to eliminate oxygen, but to uniformly maintain its concentration. Thus, the control of oxygen concentration is essential for crystalline growth. At present, the control of oxygen concentration is actively being studied based on the interdependence of various factors such as crystal rotation, crucible rotation, argon flow, pressure, magnet position and magnetic strength. However for methods using a magnetic field, the initial investment and operating costs of the equipment affect the wafer pricing. Hence in this study simulations were performed with the purpose of producing low-cost, high-quality ingots through the development of a process to optimize oxygen concentration without the use of magnets and through the following. a process appropriate to the defect-free range was determined by regulating the pulling rate of the crystals.