• Journal of Biosystems Engineering
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• v.37 no.4
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• pp.245-251
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• 2012

Purpose: Provision of accurate temperature measurement is an essential element to ensure a precise control in greenhouse environment. This study was organized to compare the effects of six solar radiation shields with different shapes for temperature measurement and find the most appropriate shield for greenhouse environment. Methods: A fan-aspirated radiation shield was designed and manufactured. Using the fan-aspirated radiation shield and five other shapes i.e., the cup shape, horizontal pipe, vertical pipe, parallel boards and commercial shields, temperature measurement was conducted over the lawn surface as well as greenhouse indoor environment. The measurement height varied at 0.5, 1.0 and 1.5 m from the floor. Results: The measured temperatures by the fan-aspirated radiation shield were 1.30-$1.49^{\circ}C$ lower than the values recorded by other different-shaped shields at 1.5 m of measurement height. As the measurement height decreases, observed differences between measured temperatures of the fan-aspirated radiation shield and other shields demonstrate a declining trend. However, at low measurement heights, the radiation emitted from the bottom surface would be the source of error in temperature measurement. Conclusions: The fan-aspirated radiation shield is a required tool for exact measurement of air temperature in greenhouse temperature control.

• Journal of Bio-Environment Control
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• v.29 no.2
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• pp.110-119
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• 2020

This study investigates the improvement in the performance of a temperature and humidity measuring system developed by Company A using the Aspirated Radiation Shield (ARS). The shield has been used in the industry and its accuracy was verified recently. The study also experimentally examines the impact of the wind speed of the ARS device on temperature and humidity. The results are summarized as follows. Before the improvement of the system, the temperature of Company A's system was up to 10.2℃ higher than that measured by the ARS device, and the measured relative humidity was approximately 20.0% lower. After improving the system, the temperature and relative humidity of nodes 1 and 2 were found to be almost identical. The temperature deviations including the maximum, mean, and minimum temperatures between those measured in node 2 and by ARS were approximately 0.2 to 0.7℃, respectively; further, the values measured by ARS tended to be slightly lower or higher. In terms of relative humidity, the ARS measurements yielded values approximately 10.0% higher immediately after sunset; otherwise, the values were approximately 1.9% lower. Moreover, when node 1 was set to minimum-middle, middle-maximum, and maximum, the deviations including the maximum, mean, and minimum temperatures of nodes 1 and 2 were 0.1 to 0.4℃, 0.0 to 0.2℃, and 0.0 to 0.5℃, respectively. The deviations including the maximum, average, and minimum temperatures of the three points of node 1 and the ARS ranged from 0.2 to 0.5℃, 0.1 to 2.2℃, and 0.1 to 1.1℃, respectively, indicating that the temperature deviation according to the wind speed was negligible. In addition, considering the results of the previous study with those from this study, the optimal wind speed to improve the temperature deviation is considered to be in the range of 1.0~2.0 m·s^-1.

• Journal of Bio-Environment Control
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• v.28 no.2
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• pp.117-125
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• 2019

This study compared the temperature and humidity measured by an aspirated radiation shield (ARS), the accuracy of which has been recently verified, and those measured by a system developed by the parent company (Company A) to investigate and improve the performance of the developed system. The results are as follows. Overall, the two-plate system had a lower radiation shielding effect than the one-plate system but showed better performance results when excluding the effect of strawberry vegetation on the systems. The overall maximum temperature ranges measured by company A's system and the ARS were $20.5{\sim}53.3^{\circ}C$ and $17.8{\sim}44.1^{\circ}C$, respectively. Thus, the maximum temperature measured by company A's system was $2.7{\sim}9.2^{\circ}C$ higher, and the maximum daily temperature difference was approximately $12.2^{\circ}C$. The overall average temperature measured by company A's system and the ARS was $12.4{\sim}38.6^{\circ}C$ and $11.8{\sim}32.7^{\circ}C$, respectively. Thus, the overall average temperature measured by company A's system was $0.6{\sim}5.9^{\circ}C$ higher, and the maximum daily temperature difference was approximately $6.7^{\circ}C$. The overall minimum temperature ranges measured by company A's system and the ARS were $4.2{\sim}28.6^{\circ}C$ and $2.9{\sim}26.4^{\circ}C$, respectively. Thus, the minimum temperature measured by company A's system was $1.3{\sim}2.2^{\circ}C$ higher, and the minimum daily temperature difference was approximately $2.9^{\circ}C$. In addition, the overall relative humidity ranges measured by company A's system and the ARS were 52.9~93.3% and 55.3~96.5%, respectively. Thus, company A's system showed a 2.4~3.2% lower relative humidity range than the ARS. However, there was a day when the relative humidity measured by company A's system was 18.0% lower than that measured by the ARS at maximum. In conclusion, there were differences in the relative humidity measured by the two company's devices, as in the temperature, although the differences were insignificant.

• Journal of the Korean Society of Safety
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• v.32 no.2
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• pp.7-13
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• 2017

An experimental study was conducted to identify the quantitative measurement bias for the bare-bead thermocouple (TC), which was widely used for measuring temperature in fire experiments. To this end, an apparatus could be controlled individually gas flow rate, preheating temperature and incident radiative heat flux was developed to simulate the thermal environments of fire. A relative measurement bias of bare-bead TC was evaluated with the comparison of double-shield aspirated TC. As a result, the relative measurement bias of bare-bead TC was gradually increased with the increase in radiative heat flux with constant gas temperature. The relative bias was also significantly increased with the decrease in gas temperature. Quantitatively, at the gas temperature of $20^{\circ}C$, the bare-bead TC had the relative bias of approximately 400% with the radiative heat flux of $20kW/m^2$ corresponding to thermal radiation level of the flashover. The present study was intend to provide fire researchers with methodologies for the reanalyses of temperature measured using bare-bead TC, radiation corrections, and validation of fire modeling.

• Journal of Bio-Environment Control
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• v.28 no.1
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• pp.78-85
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• 2019

This study was designed to examine the performance of an aspirated radiation shield(ARS), which was made at the investigator's lab and characterized by relatively easier making and lower costs based on survey data and reports on errors in its measurements of temperature and relative humidity. The findings were summarized as follows: the ARS and the Jinju weather station made measurements and recorded the range of maximum, average, and minimum temperature at $2.0{\sim}34.1^{\circ}C$, $-6.1{\sim}22.2^{\circ}C$, $-14.0{\sim}15.1^{\circ}C$ and $0.4{\sim}31.5^{\circ}C$, $-5.8{\sim}22.0^{\circ}C$, $-14.1{\sim}16.3^{\circ}C$, respectively. There were no big differences in temperature measurements between the two institutions except that the lowest and highest point of maximum temperature was higher on the campus by $1.6^{\circ}C$ and $2.6^{\circ}C$, respectively. The measurements of ARS were tested against those of a standard thermometer. The results show that the temperature measured by ARS was lower by $-2.0^{\circ}C$ or higher by $1.8^{\circ}C$ than the temperature measured by a standard thermometer. The analysis results of its correlations with a standard thermometer reveal that the coefficient of determination was 0.99. Temperature was compared between fans and no fans, and the results show that maximum, average, and minimum temperature was higher overall with no fans by $0.5{\sim}7.6^{\circ}C$, $0.3{\sim}4.6^{\circ}C$ and $0.5{\sim}3.9^{\circ}C$, respectively. The daily average relative humidity measurements were compared between ARS and the weather station of Jinju, and the results show that the measurements of ARS were a little bit higher than those of the Jinju weather station. The measurements on June 27, July 26 and 29, and August 20 were relatively higher by 5.7%, 5.2%, 9.1%, and 5.8%, respectively, but differences in the monthly average between the two institutions were trivial at 2.0~3.0%. Relative humidity was in the range of -3.98~+7.78% overall based on measurements with ARS and Assman's psychometer. The study analyzed correlations in relative humidity between the measurements of the Jinju weather station and those of Assman's psychometer and found high correlations between them with the coefficient of determination at 0.94 and 0.97, respectively.