• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.41 no.5
• /
• pp.357-365
• /
• 2013

In this study, forces and moments were measured on a projectile which consisted of a missile configuration body(shell) and a head installed control fins. The shell and the head were separated each other and the shell was rotated by an electric motor. The head rotated reversely against the rotational direction of the shell. The rotational force on the head was obtained from a couple of fixed fins of which angular displacement were set to the rotational direction equally. The air velocity was 40m/s on the experiment and the Reynolds number based on the diameter of head was $1.3{\times}10^5$. The other couple of fins were used to control the position and direction of the projectile by changing the angular displacement. From this experiment, the variation of force and moment were measured on the rotating projectile, and the effective amplitude and frequency were obtained through the FFT analysis.

• International Journal of Clinical Preventive Dentistry
• /
• v.14 no.4
• /
• pp.228-234
• /
• 2018

Objective: The authors have experimented for the artificial plaque removal effect of several kinds of 360 degree rotating head typed tooth-brushes with sonic vibratory actioned by using of automatic machine for horizontal scrub method in order to find the better toothbrush type for plaque removal. Methods: The experiment was conducted on three medium to 360 degree rotating head toothbrushes, a medium sized toothbrush and a medium sized toothbrush, and a flat toothbrush consisting of 30 ordinary toothbrushes. A brushing machine with horizontal scrubbing was manufactured and had variations of the end of the bristle attached to or near the surface of the teeth, a vibrating wave action force of 16,000 or 18,000 cycles per minute, and a working time of 2 or 3 minutes. The tooth removal effect was confirmed by scanning and analyzing images with a computer program after automatic brushing with the machine. The elimination rate results for each group were analyzed using the independent t-test and one-way ANOVA test. Results: It revealed the most in removal effect for the artificial plaque in such conditions as action at near the tooth surface with 18,000 cycle for 3 minutes in case of using A, B, and C tooth-brush. And it has more removal effect rate than for using the plane tooth-brush (p<0.05). Conclusion: It was recommended to develop the 360 degree rotating head and vibratory toothbrush focusing to use near the tooth surface with 18,000 cycles of vibration for 3 minutes at one site of the teeth area.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.16 no.2
• /
• pp.281-289
• /
• 1992

In an attempt to simulate the flows in the computer hard disk storage system, flow visualization and quantification by image processing technique were applied. Model geometry was constructed while the dynamic similitude was maintained. Circumferential velocities were mapped out in the transient spin-up phase. During the spin-up phase, fluid close to the rotating inner hub approached the solid body rotation, while the fluid in the outer region showed the velocity deficit compared to the rotating speed of the disks. Effects of presence of read/write head arm assembly between the gap were studied by changing the location of the head. The experimental results could serve as a benchmark for the alidation of numerical codes.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.16 no.1 s.106
• /
• pp.75-80
• /
• 2006

This paper introduces the mechanism of the ESD(electrostatic discharge) in the HDD spindle system using FDBs(fluid dynamic bearings). When a HDD(hard disk drive) spindle system is rotating, triboelectric charging occurs in the FDBs through the friction between the lubricant and the rotating shaft or between the lubricant and stationary sleeve. And this electrostatic charge is accumulated in the rotating parts of the HDD spindle system because they are insulated from the ground by the lubricant. This research shows experimentally that the behavior of electric charge and discharge in the FDB spindle system is the same as that of a capacitor. It also measures the electrostatic voltage difference between the rotating and stationary parts in the FDB spindle system due to the change of humidity, supporting load and motor speed. This research shows that the control of ESD is required in the HDD spindle system using FDBs, because the electrostatic charge accumulated in the FDB spindle system may cause the breakdown damage of the GMR head and data loss consequently.

• The Journal of Churna Manual Medicine for Spine and Nerves
• /
• v.6 no.1
• /
• pp.75-88
• /
• 2011

Objectives : The purpose of this study is to investigate the clinical application of Muscle Energy Techniques(MET) and Oriental Medicine to a patient who had Acquired Rotating Torticollis. Methods : A patient diagnosed as acquired torticollis was hospitalized at Buchun Jaseng hospital of Oriental Medicine for 28 days and she was treated by MET, herbal medicine and acupuncture. To measure the outcome of the patient's improvement, we observed Numerical Rating Scale(NRS), Neck Disablility Index(NDI), Tsui's Scale and the X-rays of Whole spine. Results : After being treated by MET and Oriental Medicine, the patient's pain was reduced and the head rotating was significantly improved. The improvement of patient in the NRS, NDI, Tsui's Scale was detected and the X-ray of Whole spine became normal. Conclusions : As seen in this case, complexed therapy with MET and Oriental Medicine is effective treating method to control pain and head rotating for patients with acquired rotating torticollis.

• Journal of Drive and Control
• /
• v.9 no.3
• /
• pp.29-36
• /
• 2012

The hydraulic cylinder is used for actuating the roller-link type rotating floodgate which controls the volume of water in the reservoir. The locating points of hydraulic cylinder are restricted to the limited space and determined to minimize the cylinder force necessary for actuating the floodgate. Generally, the head end point of cylinder is fixed at underground and the rod end point of cylinder is connected to the support link. Therefore there exist three design variables to be determined to minimize the cylinder force within the rotating range of floodgate. First, the mathematical model of the roller-link type rotating floodgate is derived to find the cylinder force corresponding to the floodgate angle. Then, the optimal locating point of hydraulic cylinder is searched using the complex method that is one kind of constrained direct search method.

• Tribology and Lubricants
• /
• v.3 no.1
• /
• pp.31-38
• /
• 1987

This paper describes a theoretical model for the prediction of the spacing profile between a flexible magnetic tape tensioned around a rotating drum and a protruding head mounted on the drum. The analysis is based on the coupled equations controlling the elastic deformation of the tape and the hydrodynamic pressure of the gas film. Some results are presented for a cylindrical head.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2014.10a
• /
• pp.141-145
• /
• 2014

A minimally appropriate time delay of audio data processing is investigated for rendering virtual sound source direction in real-time head-tracking environment under headphone listening. Less than 3.7 degree of angular mismatch should be maintained in order to keep desired sound source directions in virtually fixed while listeners are rotating their head in a horizontal plane. The angular mismatch is proportional to speed of head rotation and data processing delay. For 20 degree/s head rotation, which is a relatively slow head-movement case, less than total of 63ms data processing delay should be considered.

• 유체기계공업학회:학술대회논문집
• /
• 2003.12a
• /
• pp.333-339
• /
• 2003

Steady and unsteady cavitation characteristics of turbopump inducer were investigated in this paper. To see the effect of blade angle on the inducer performance, three inducers with inlet tip blade angle of $7.8^{\circ},\;7.0^{\circ},\;6.1^{\circ}$, respectively, were tested. For $7.8^{\circ},\;7.0^{\circ}$ inducers in the non-cavitating condition, head decreased linearly with flow rate, but head-flow rate curve had a dip at the flow coefficient ${\Phi}=0.065\;for\;6.1^{\circ}$ inducer. Rotating cavitation and cavitation surge were found in the $7.8^{\circ},\;7.0^{\circ}$ inducers in the cavitation tests. During the rotating cavitation one cell rotated at the same rotational speed as that of the inducer. The cavitation surge did not rotate and the oscillating frequency was $7{\sim}20\;Hz$. From the curve of the critical cavitation number versus flow rate, it was found that the steady cavitation performance of $6.1^{\circ}$ inducer was much lower than that of $7.8^{\circ},\;7.0^{\circ}$ inducers.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2005.11a
• /
• pp.318-323
• /
• 2005

This paper introduces the mechanism of the ESD (Electrostatic discharge) in the HDD spindle system using FDBs (Fluid Dynamic Bearings). When a HDD (Hard Disk Drive) spindle system is rotating, triboelectric charging occurs in the FDBs through the friction of the lubricant between the rotating shaft and stationary sleeve. And this electrostatic charge is accumulated in the rotating part of the HDD spindle system because it is insulated from the ground by the lubricant. This research shows experimentally that the behavior of electric charge and discharge in the FDB spindle system is the same as that of a capacitor. It also measures the electrostatic charge and discharge of the FDB spindle system due to the chanse of humidity, supporting load and motor speed. This research shows that the control of ESD is required in the HDD spindle system using FDBs, because the electrostatic charge accumulated in the FDB spindle system may cause the breakdown damage of the GMR head and data loss consequently.