• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.335.2-335
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• 2002

Non-singular boundary element method (BEM) codes are developed in acoustics application. The BEM code is then used to calculate unknown boundary surface normal displacements and surface pressures from known exterior near field pressures. And then the calculated surface normal displacements and surface pressures are again applied to the BEM in forward in order to calculate reconstructed field pressures. (omitted)

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.645-646
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• 2006

The oscillation amplitude of a probe tip is an important parameter to determine the resolution of atomic force microscopy (AFM) techniques. In this work, we introduce a new method for the measurement of the oscillation amplitude of a quartz tuning fork tip sub-nanometer resolution.

• Proceedings of the Optical Society of Korea Conference
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• 2002.11a
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• pp.260-261
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• 2002

For Near-field Scanning Optical Microscopy measurements, the fiber tip is glued on the side of one of the tuning fork prongs vertically to its extended direction. Higher Q-factor is attainable in this geometry than in the arrangement with the fiber tip parallel to the prong. A simple mechanical design is applied to hold the fiber tip above the gluing point. The overall tuning fork-fiber tip assembly gives another advantage of the flexible Q-factor enhancement. With this treatment, Q-factor higher than 3000 is easily achievable. As an operating instance, a grating is scanned for its one dimensional topographical image.

• Proceedings of the Korean Magnestics Society Conference
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• 2007.05a
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• pp.101.2-101.2
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• 2007

• Proceedings of the Optical Society of Korea Conference
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• 2006.07a
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• pp.145-146
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• 2006

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.697-698
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• 2007

• Proceedings of the Optical Society of Korea Conference
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• 2004.02a
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• pp.230-231
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• 2004

• Journal of Preventive Medicine and Public Health
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• v.24 no.1 s.33
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• pp.93-97
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• 1991

The time honoured tuning fork at present widely available for examining vibration sensation is brought about the problem of great interobserver variation. To resolve t his problem, author developed a divice using electric magnet that stimulates constantly tuning fork. The perception time of vibration from tunung fork by this device was tested on the index finger of dominant hand of twenty eight subjects. It was 12.44 seconds on average and ranged from 9.47 to 17.25. Coefficient of variation of it was 16.89 percent. Correlation coefficient between test and retest after 30 minutes was 0.957(p<0.01). This device is portable. Test procedure in non-invasive, non-aversive and simple, can be performed within one minute, and does not require the skilled technician. It is felt that this device testing vibration perception time is suitable as screening tool for early detection of occupational peripheral neuropathy.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1528-1532
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• 2000

The conventional optics and near field optics are compared numerically in the view points of the spot size and propagation characteristics. The decaying characteristics of near field light require the optics to access the object within several tens of nanometers. Therefore the gap control is one of the main issues in the near field optics area. In this paper the gap control is done by using the shear force of the NF(Near Field) probe and the characteristics are examined. The probe is modeled as a 2'nd order mass-spring-damper system driven by a harmonic force. The primary cause of the decrease in vibration amplitude is due to the damping force - shear force - between the surface and the probe. Using the model, damping constant and resonance frequency of the probe is calculated as a function of probe-sample distance. Detecting the amplitude and phase shift of the NF probe attached to the high Q-factor piezoelectric tuning fork, we can control the position of the NF probe about 0 to 50nm above the sample. The feedback signal to regulate the probe-sample distance can be used independently for surface topography imaging. 3-D view of the shear force image of a testing sample with the period of $1{\mu}m$ will be shown.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1971-1973
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• 1996

In this paper various types of gyroscope fabricated by micromachining technologies were reviewed. Four common types of gyroscope reported in the past few years are beam, tuning fork, gimbal, and vibrating shell structure made by surface micromachining using sacrificial layer, bulk micromachining using RIE, or electroplating method. In the study of these new gyroscopes, the fabrication methods, advantages and disadvantages of each structure were examined as well as the direction of development in the future.