• The Journal of the Acoustical Society of Korea
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• v.19 no.3
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• pp.92-99
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• 2000

In this paper, theoretical acoustic sensitivity was derived to describe acousto-optic transduction property of the mandrel type fiber optic acoustic sensor with respect to external acoustic field. The acoustic sensitivity was analyzed in relation to both material properties and geometrical influence factors of the constitutional parts of the sensor, analytically. Validity of the theoretical results were verified through comparison with the finite element analysis results. The variation trends of the sensitivity of the sensor in relation to the studied parameters showed good agreement for the two analysis methods. According to the results, it is considered more economical to design the basic structure of the sensor with the analytic equations developed in this paper, and then to carry out further detailed analysis with the finite element method for specific points of design interest.

• Korean Journal of Optics and Photonics
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• v.15 no.5
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• pp.461-468
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• 2004

A finite model eye of visual acuity 24/20 in emmertropia was presented. We determined the image intensity profile on retina using optical transfer function of model eye, and compared with clinical data. The retinal contrast sensitivity function based on the Stiles-Crawford effect, photopic response, diffraction, aberration, retinal contrast sensitivity, and pupil size is calculated. Visual acuity for human eye could be predicted by examining the modulation transfer function of a bar target and retinal contrast sensitivity function. This visual acuity was evaluated for pupil diameters ranging from 1 to 8 mm.

• Journal of the Korea institute for structural maintenance and inspection
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• v.3 no.3
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• pp.237-243
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• 1999

Recently, there has been considerable interest in the development of fiber-optic sensors based on fiber Bragg gratings (FBGs), which can be made into Ge-doped fiber's core by UV phase mask or holographic methods. A good sensitivity and small size of this sensor make it an ideal candidate for distributed sensing in smart structures or other structural monitoring applications. In this study, fiber optic Bragg grating sensor, which could be applied to measure the absolute strains, was constructed and the strain sensitivity of this sensor was investigated in order to apply to the structural health monitoring. Fiber Fabry-Perot (FFP) filter has been used to detect the optical signals instead of optical spectrum analyzer. It has been convenient to determine the structural strains from the output signal of FBGs. The fiber optic Bragg grating sensor was attached on the aluminum beam near the electrical strain gage to measure the same strain. The relationship between strain and fiber signal was linearly fitted. The strain sensitivity of the fiber optic Bragg grating sensor was determined as $l.57{\mu}{\varepsilon}/{\mu}sec$ from the aluminum beam test.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.478-481
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• 1995

This paper presents the system demonstrator for an optical fiber sensor system developed as a technological evaluator suitable for generic sensric sensing applications. The new type of fiber-optic sensor employed a diaphragm displacement transforms pressure into optical intensity. Form this sensing technique, we can know the variation of source intensity, the loss of a optical fiber, and the reflectivity of the diaphragm surface. Experimental results are applied to the low-pressure transducer suitable for measuring miniature pressure.

• Journal of KSNVE
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• v.8 no.1
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• pp.87-98
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• 1998

A Precise actuator in the pick-up of a DVDR/P(Digital Video Disk Recorder/Player) is required to control position accurately. Therefore, in order to develop a reliable actuator, dynamic characteristics of each part in an actuator should be examined closely. This paper presents systematic design process of an actuator using various analysis methods to confirm fundamental capability and solve performance problems related to dynamic characteristics of an actuator beforehand. Particularly, sensitivity analysis is presented through the program using mass moment of inertia and general equations of rigid body. Through the result of sensitivity analysis, important inferiority causes of actuator are selected and reduced. In the end, dynamic characteristics of manufactured actuators are improved considerably.

• Journal of the Optical Society of Korea
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• v.9 no.4
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• pp.169-172
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• 2005

The phase sensitivity of the coincidence detection in one output port of a Mach-Zehnder interferometer is analysed for twin Fock state inputs. Firstly, the ideal detectors with quantum efficiency of unity are assumed for the detection of the output photons. The sensitivity is found out to be independent of the photon number of input light, which means that the Heisenberg limit cannot be reached in the coincidence detection even with ideal detectors. Secondly, the practical detectors with quantum efficiencies less than unity are discussed.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.2
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• pp.79.1-79.1
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• 2019

The Schwarzchild-Chang telescope is a confocal off-axis two mirror telescope with D = 50 mm, F = 100 mm and FOV = 8 ° × 8 °. Unlike common off-axis telescopes, the mirrors of the Schwarzchild-Chang telescope share their focal points to remove the linear astigmatism. In this poster, we show the alignment process of the Schwarzchild-Chang telescope with wavefront measurement and the sensitivity table method. Wavefront is measured using the Shack-Hartmann sensor, and Zernike polynomials are obtained from measured wavefront. Sensitivity table method is to calculate alignment errors from the Zernike coefficients. As a result, we evaluate tilt, decenter, and despace of each mirror of linear astigmatism-free con-focal off-axis system.

• Journal of the Korea Society of Computer and Information
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• v.15 no.3
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• pp.65-72
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• 2010

We propose the asymmetric 2.5Gbps/622Mbps PON(Passive Optical Network) in order to reduce the bandwith of filter at receiver with inverse RZ(Return to Zero) code coded downstream and NRZ(Non Return to Zero) upstream re-modulation. I theoretically analyze BER(Bit Error Rate) performance and the power sensitivity with the optimal threshold level by performing simulation with MATLAB according to the types of downstream data. The results have shown that the optimal threshold level at the optical receiver could be saturated at 0.33 as the optical received power increase more than -26dBm to keep $10^{-12}$ of BER to a minimum. Also the power sensitivity is more improved by about 3dB by fixing the threshold level at 0.33 than the conventional receiver. The proposed system can be a useful technology for optical access networks with asymmetric upstream and downstream data rates because the optical receiver can be used without controlling threshold levels and that does not require a light source in optical network unit (ONU) and its control circuits in the optical line termination (OLT).

• Korean Journal of Materials Research
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• v.11 no.4
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• pp.247-250
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• 2001

We have fabricated and evaluated a new Si pin photodiode for red light detection with the web patterned $p^{+}$ -shallow diffused region in the light absorbing area. From the measurements of electro-optical characteristics under the bias of -5V, the junction capacitance of 4pF and the dark current of 235pA were obtained. When the 1.6㎼ optical power with peak wavelength of 670nm was incident on the device, the optical signal current of 0.48$\mu\textrm{A}$ and the responsivity of 0.30A/W were obtained. The fabricated device showed the improved sensitivity compared to the conventional circular type device and the maximum spectral response in a spectrum of 670~700nm. The web-patterned Si photodiode can be expected to have the good discrimination characteristics between digital signals in the application of red light optics.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.83-84
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• 2006

For phase transition method, good recording sensitivity, low heat radiation, fast crystallization and hi-resolution are essential. Also, A retention time is very important part for phase transition. In our presentation wall, we chose Ge-Se-Te material to use a Se material which has good optical sensitivity than Sb. A Ge-Se-Te sample was fabricated and Irradiated with He-Ne laser and DPSS laser to investigate a reversible phase change by light.