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Author: search.filters.author.Yokpradit, Anchyza

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    Item type:Publication,
    Cloud-based optical characterization of hard disk drive recording heads
    (2018-01-01)
    Khunrattanasiri, Weerayuth
    ;
    Yokpradit, Anchyza
    ;
    Tongloy, Teerawat
    ;
    Boonsang, Siridech
    In the hard disk drive (HDD) industry, the measurement of flying height is crucial for the verification of the recording head air-bearing design. The flying performance of recording heads has to be measured and compared with the original design to assure the reliability of HDDs. Optical interferometry is normally used to measure the flying height of recording heads. The key parameter for setting up the measurement is the refractive index, whose values normally deviate depending on machine conditions during the manufacturing processes. The variation in refractive index cannot be identified during flying height measurement because there is no on-line technique for doing so. In this paper, we present a novel technique using inhouse designed micro-ellipsometry to measure the complex refractive index combined with data transfer to a private cloud network via the Internet of Things message queuing telemetry transport (IoT MQTT) protocol. Therefore, the measurement of the complex refractive index can be carried out for each recording head and we can improve the precision of the flying height measurement. In addition, the information about refractive index not only can be shared with a flying height tester to correct the variation in each recording head but also can be used to assist air-bearing designers in the instantaneous validation of their design.
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    A Real-time rheological measurement for biopolymer 3D printing process
    (2018-01-01)
    Yokpradit, Anchyza
    ;
    Tongloy, Teerawat
    ;
    Kaewpirom, Supranee
    ;
    Boonsang, Siridech
    Biopolymers combined with 3D printing technology for tissue engineering have been extensively used in many biomedical applications such as organ and tissue regeneration. The 3D printing technology generally relies on a continuous dispensing process, which is usually known as complicated dynamic processes. This is primarily caused by the rheological properties of materials. In addition, the primary concern for biopolymer printing is the timedependent variation of material properties such as viscosity during the printing process. The variation of rheological properties significantly affects the printing process especially the volume flow rate control. In general, the measurement of rheological properties is carried out before the dispensing process. The setting up of fluid flow control is usually performed according to parameters derived from the premeasured rheological values. However, such a method may not provide optimized parameters for printing control with some biopolymers. An innovative method of measuring rheological properties is proposed in this paper. An image processing procedure is employed to determine the fluid flow at a certain time in the fluid dispensing process. Experiments were carried out in which the rheological properties of poly- (vinyl alcohol) (PVA) and poly-(vinyl alcohol)/chitosan (PVA/CS) aqueous solutions used for dispensing the polymers were evaluated at different time stamps and applied pressures. The measured flow rates were used to construct a pressure-dependent fluid flow rate curve as a function of time to identify the rheological properties of fluid materials under specific times and conditions.