• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.199.2-199.2
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• 2010

The main purpose of the calibration procedure is to perform a one to one comparison of the reference pyranometer and the test pyranometer. In order to achieve this, both pyranometers need to be exposed to exactly the same irradiance, under the same circumstances. There are a number of error sources that could result in a wrong measurement. Most importantly Lamp instability, pyranometer offsets, thermal offsets of junctions, voltmeter offset, voltmeter instability, reference pyranometer instability, tilting of the pyranometers and differences in sensor height. Another sun-disc calibration procedure compares the computed vertical component of the direct irradiance as measured by a pyranometer with that measured by the pyranometer to be calibrated. Readings are taken with the levelled pyranometer on a clear day. Firstly the global irradiance and then the diffuse component are measured. Simultaneously measurement of direct irradiance is made with the pyrheliometer. The ways of performing the calibration and the subsequent calculation have been chosen such that the effect all these error sources has been eliminated as much as possible.

• Journal of the Korean Institute of Gas
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• v.18 no.2
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• pp.48-54
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• 2014

A unique optical waveguide structure is proposed to enhance the optical characteristics of alcohol screening sensors. This structure is then simulated. The structure consists of two elliptical waveguides that have a common focus to one side and has an IR source and detector at each of the other focal points of the ellipses. When the angle between the two elliptical waveguides is increased from 30 degrees to 90 degrees, the maximum level of irradiance is greatly decreased, falling from $2.23{\times}10^6 W/m^2$ to $5.74{\times}10^5W/m^2$. However, the diameter of the incident rays is at a minimum of 1.86mm and the total incident flux is less than 10% lower when compared to the structure at $90^{\circ}$. It can be seen from the simulation results that this structure might enhance the sensitivity of an optical gas sensor which has a large absorption wavelength.

• Journal of Sensor Science and Technology
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• v.7 no.3
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• pp.154-162
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• 1998

A planar Bi-Sb multijunction thermal converter with high thermal sensitivity and small ac-dc transfer error has been fabricated by preparing the bifilar thin film Pt-heater and the hot junctions of thin film Bi-Sb thermopile on the $Si_{3}N_{4}/SiO_{2}/Si_{3}N_{4}$-diaphragm, which functions as a thermal isolation layer, and the cold junctions on the dielectric membrane supported with the Si-substrate, which acts as a heat sink, and its ac-dc transfer characteristics were investigated with the fast reversed dc method. The respective thermal sensitivities of the converter with single bifilar heater were about 10.1 mV/mW and 14.8 mV/mW in the air and vacuum, and those of the converter with dual bifilar heater were about 5.1 mV/mW and 7.6 mV/mW, and about 5.3 mV/mW and 7.8 mV/mW in the air and vacuum for the inputs of inside and outside heaters, indicating that the thermal sensitivities in the vacuum, where there is rarely thermal loss caused by gas, are higher than those in the air. The ac-dc voltage and current transfer difference ranges of the converter with single bifilar heater were about ${\pm}1.80\;ppm$ and ${\pm}0.58\;ppm$, and those of the converter with dual bifilar heater were about ${\pm}0.63\;ppm$ and ${\pm}0.25\;ppm$, and about ${\pm}0.53\;ppm$ and ${\pm}0.27\;ppm$, respectively, for the inputs of inside and outside heaters, in the frequency range below 10 kHz and in the air.