• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.3
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• pp.166-173
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• 2012

This study is about comparison of thermal and flow characteristics on the wind & radiant heat shield with STS mesh type screen for offshore. Numerical analysis was conducted to find transmission coefficient in the mesh and then analyse the flow characteristics about wind & radiant heat shield. The experiment method of solar radiation has been used as thermal radiation source to get the performance of radiant heat shield measurement. The sensor radiation device has been used to measure the reduction of solar radiation with various size of cells and at a distance of 0.5m and 1m from the cold face of the wind & radiant heat shield.

• 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 Astronomy and Space Sciences
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• v.20 no.4
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• pp.393-402
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• 2003

The Multi-Spectral Camera (MSC) is the payload of KOMPSAT-2 which is designed for earth imaging in optical and near-infrared region on a sun-synchronous orbit. The telescope in the MSC is a Ritchey-Chretien type with large aperture. The telescope structure should be well stabilized and the optical alignment should be kept steady so that best images can be achieved. However, the MSC is exposed to adverse thermal environment on the orbit which can give impacts on optical performance. Solar incidence can bring non-uniform temperature rise on the telescope tube which entails unfavorable thermal distortion. Three ways of preventing the solar radiation were proposed, which were installing external mechanical shield, internal shield, and maneuvering the spacecraft. After trade-off study, internal sun shield was selected as a practical and optimal solution to minimize the effect of the solar radiation. In addition, detailed designs of the structure and sunshield were produced and analyses have been performed. The results were assessed to verify their impacts to the image quality. It was confirmed that the internal sunshield complies with the requirements and would improve image quality.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.815-820
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• 2002

MSC as a payload of KOMPSAT-2 is an optical telescope for earth imaging on a sun-synchronous orbit. The MSC is a Ritchey-Chretien type telescope composed of hyperbolic primary and secondary mirrors with focal correcting lenses. Their relative positions should be kept aligned during imaging operation. However, the MSC is exposed to adverse thermal environment on orbit which can have some impacts on optical performance as well as structural endurance. Solar incidence can cause non-uniform temperature rise on the tube which entails unfavorable thermal distortion. Three options were proposed, which were internal shield, external mechanical shield and spacecraft maneuvering. After the trade-off studies, internal sun shield was selected as a realistic and optimal solution to minimize the effect of the solar radiation. In this paper, pros and cons are explained for the three possible choices and a design of the internal shield is discussed.

• Atmosphere
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• v.29 no.1
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• pp.61-74
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• 2019

To investigate the observational environment, sky line and skyview factor (SVF) are calculated using a digital elevation model (DEM; 10 m spatial resolution) and 3 dimensional (3D) sky image at radiation site, Gangneung-Wonju National University (GWNU). Solar radiation is calculated using GWNU solar radiation model with and without the sky line and the SVF retrieved from the 3D sky image and DEM. When compared with the maximum sky line elevation from Skyview, the result from 3D camera is higher by $3^{\circ}$ and that from DEM is lower by $7^{\circ}$. The SVF calculated from 3D camera, DEM and Skyview is 0.991, 0.998, and 0.993, respectively. When the solar path is analyzed using astronomical solar map with time, the sky line by 3D camera shield the direct solar radiation up to $14^{\circ}$ with solar altitude at winter solstice. The solar radiation is calculated with minutely, and monthly and annual accumulated using the GWNU model. During the summer and winter solstice, the GWNU radiation site is shielded from direct solar radiation by the west mountain 40 and 60 minutes before sunset, respectively. The monthly difference between plane and real surface is up to $29.18M\;m^{-2}$ with 3D camera in November, while that with DEM is $4.87M\;m^{-2}$ in January. The difference in the annual accumulated solar radiation is $208.50M\;m^{-2}$ (2.65%) and $47.96M\;m^{-2}$ (0.63%) with direct solar radiation and $30.93M\;m^{-2}$ (0.58%) and $3.84M\;m^{-2}$ (0.07%) with global solar radiation, respectively.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.4
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• pp.309-318
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• 2019

The thermal design of the Lunar Terrain Imager (LUTI) on the Korean Pathfinder Lunar Orbiter (KPLO) was performed and the soundness of the thermal design was verified by thermal analysis. The thermal environment of the lunar mission orbit should be reflected in the thermal design because the IR radiation of the lunar surface is important, unlike the earth orbit. The components or modules exposed to the outside of the satellite are insulated with MLI as much as possible, but the camera tube and the radiator are functionally exposed, so the thermal shield using the concept of radiation shape factor is mounted on the front to mitigate IR radiation. The IR emissivity is important in the front side of the radiator that receives little solar radiation, and components that are susceptible to thermal deformation such as the tube use a radiation heater to minimize the temperature gradient. Through the investigation of computational results, it was confirmed that the thermal design of LUTI is stable in various situations.

• 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.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.3
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• pp.234-240
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• 2015

In the face of the world's growing energy storage needs, liquid hydrogen offers a high energy density solution for the storage and transport of energy throughout society. A 5 L liquid hydrogen storage tank has been designed, fabricated and tested to investigate boil-off rate of liquid hydrogen. As the insulation plays a key role on the cryogenic vessels, various insulation methods have been employed. To reduce heat conduction loss, the epoxy resin-based insulation supports G-10 were used. To minimize radiation heat loss, vapor cooled radiation shield, multi-layer insulation, and high vacuum were adopted. Mass flow meter was used to measure boil-off rate of the 5 L cryogenic vessel. A series of performance tests were done for liquid nitrogen and liquid hydrogen to compare with design parameters, resulting in the boil-off rate of 1.7%/day for liquid nitrogen and 16.8%/day for liquid hydrogen at maximum.

• Journal of Bio-Environment Control
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• v.30 no.4
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• pp.304-311
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• 2021

This Experiment was conducted to determine the effects of light shield materials when melon grown inside a plastic greenhouse in summer season. The average temperatures were 36.6℃, 34.5℃ and 34.0℃ respectively for the control(non-shield), coating agent, and the white net. The light transmittances were 69% and 75%, respectively inside the greenhouse treated with the coating agent and white net immediately after applicants, compared with that inside the control greenhouse. At the 40 and 80 days after treatment, the light transmittances for the coating agent were 92% and 98%, respectively, indicating it was slowly decomposed and removed, but there was no change in the transmittance for the white net. While the leaf number did not differ among the treatments, the plant height was higher in the white net and shading agent than in control. The weight of the leaves, fresh-weight and dry-weight were no different from that of shading, but it became heavier in the later stages. The marketable fruit yield was increased by 6% for white nets and 5% for the coating agent compared to control, there was no statistical significance. Therefore, coating agent is considered as an effective method to lower temperature during high temperature period, but it is preferable to use it in consideration of cultivation period, because the coating agent is gradually removed.