• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.2159-2161
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• 2000

The LEDs are used for signal lights including traffic signals and telecommunication equipments. Advanced foreign countries are making R&D of ultra high intensity LEDs, and the LEDs are expected to new light source. Optical characteristics by measurements of 14 LEDs; each 2 of 3$\Phi$ R/G/Y LEDs, each of 5$\Phi$ Y/G/Y LEDs and each of high intensity 5$\Phi$ R/G/B/A/W LEDs. Comparison on chromaticity coordinate of high intensity 5$\Phi$ White LED by forward V/I.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.5
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• pp.1300-1307
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• 1995

The effect of thermal stratification on the turbulent dispersion from a fine cylindrical heat source was experimentally examined in a wind tunnel with and without a strong temperature gradient. A 0.5 mm dia. nichrome wire was used as a line heat source. Turbulent intensities, r.m.s. value of temperature and convective heat fluxes were measured by using a hot-wire and cold-wire combination probe. The results show that the peack value and the spread of the vertical turbulent intensity for the stratified case are far lower than those in the neutral case, which indicates that the stable temperature gradient suppresses the vertical velocity component. All of the third order moments including heat fluxes measured in the stable condition have very small values than those of the neutral case. This nature suggests that the decrease of scalar fluctuations in the stably stratified flow is mainly due to the suppression ofthe turbulent diffusion processes by the stable stratification. A simple gradient model with a composite timescale which has a simple weighted algebraic mean between dynamic and thermal time scale yields reasonably good numerical values in comparison with the experimental data.

• 연구논문집
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• s.32
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• pp.65-76
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• 2002

The intensity of x-ray or gamma-ray is attenuated according to density and thickness of the transmitted medium. In this study, by using this principle, on-line real-time radiometric system was developed using a 128 channels linear array of solid state detectors to measure wall thickness of insulated piping system. This system uses a Ir-192 as a gamma ray source and detector is composed of BGO scintillator and photodiode. Ir-192 gamma ray source and linear detector array mounted on a computer controlled robotic crawler. The Ir-192 gamma ray source is located on one side of the piping components and the detector array on the other side. The individual detectors of the detector array measure the intensity of the gamma rays after passing through the walls and the insulation of the piping component under measurement. The output of the detector array is amplified by amplifier and transmitted to the computer. This system collects and analyses the data from the detector array in real-time. The maximum measurable length of pipe is 120cm/mm. in the case of 1mm scanning interval.

• Transactions on Electrical and Electronic Materials
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• v.16 no.4
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• pp.201-205
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• 2015

This paper dealt with the condensing technology of an LED light source that uses a parabolic reflector to replace a searchlight equipped with a xenon lamp. A ray-tracing simulation was conducted to analyze the influence of the diameter of the reflector and the size of the light source on light condensing. The combination of a parabolic reflector with a diameter of 620 mm and a focal distance of 220 mm, and a 9 mm multi-chip package (MCP) with a luminous flux of 7,000 lm showed the narrowest beam angle. The luminous intensity at the center was measured at 7.7×10⁶ cd. The distance between the light source and the point where the illuminance was 1 lx was calculated to be 2.8 km. The power consumption of the system was 95 W, which is only 9.5% of that of the 1 kW xenon searchlight, and the beam angle was 1.03°. In a site experiment, it was confirmed that the light ray reflected from the LED searchlight proceeds forward without any diffusion because of the narrow beam angle.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1998.06b
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• pp.122-128
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• 1998

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.04a
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• pp.222-223
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• 2009

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.281-282
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• 2012

• 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.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.275-276
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• 2011

We have investigated the holographic grating formation on Ag-doped amorphous chalcogenide As2Se3 thin films with Ag layer. The basic optical parameter which is a refractive index and extinction coefficent was taken by n&k analyzer. The source of laser was selected based on these parameter. Holographic gratings have been formed using He-Ne laser (wavelength: 632.8 nm) Diode Pumped Solid State laser (DPSS, wavelength: 532.0 nm) under [P:P] polarized the intensity polarization holography. The diffraction efficiency was obtained by +1st order intensity.

• The Journal of the Acoustical Society of Korea
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• v.6 no.3
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• pp.17-22
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• 1987

This study is to propose more reliable test method in evaluating the sound insulation performance of building element in fields. This method involves the measurements of the incident acoustic intensity and transmitted surface intensity. The incident intensity is determined from measurements of the space averaged sound pressure level in source room. The transmitted surface intensity is measured directly using one microphone and one accelerometer. The results of experiments indicate that this new method makes it possible to give more reliable data than the conventional field test method. The values of trans-mission loss measured by this new method are compared favorably with those obtained using the sound intensity method and theoretical calculation(mass law).