• Aerospace Engineering and Technology
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• v.6 no.1
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• pp.64-73
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• 2007

A Large thermal vacuum chamber (LTVC) for space environment simulation on large satellites was successfully developed and constructed by KARI (Korea Aerospace Research Institute) in Korea with a local company. This chamber has an effective diameter of 8 meters and depth of 10 meters, and is composed of vacuum system, thermal control system, and anti-vibration system. Temperature below $-190^{\circ}C$ is maintained over the thermal shroud wrapping a satellite under $3.7{\times}10^{-5}Pa$ ($5{\times}10^{-7}torr$) vacuum level, and optical test can be done in this chamber by seismic mass with $10^{-5}g_{rms}$ or lower vibration level. In addition, the shroud temperature can be increased up to $123^{\circ}C$ using halogen lamps. Chamber control program based on PLC (Programmable Logic Controller) could control this large thermal vacuum chamber automatically.

• Journal of the Korean Vacuum Society
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• v.21 no.6
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• pp.287-294
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• 2012

In the high vacuum condition of the space, outgassing from any assembly of satellite can contaminate satellites, especially second surface mirror and optical lens, it cause satellite to fail in own missions. Therefore, all unit shall be check for compatibility with vacuum using CVCM (Collected Volatile Condensable Material) and TML (Total Mass Loss) in advance. CVCM and TML of the PZT-5 piezoelectric ceramic vibrator has less than 0.1% and 1.0% respectively. Also, it has less than 500 $ng/cm^2/hr$ of Thermoelectric Quartz Crystal Microbalance for vacuum bake-out test using high temperature(more than $80^{\circ}C$) and high vacuum (less than $5.0{\times}10^{-3}$ Pa). Thus, piezoelectric ceramic vibrator may be employed in the vacuum environments. Finally, it can be confirmed that the characteristics change of the piezoelectric ceramic vibrator is less than 1% under vacuum environments.

• Aerospace Engineering and Technology
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• v.12 no.1
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• pp.32-39
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• 2013

All spacecraft components shall be checked for compatibility with vacuum using CVCM and TML in advance. CVCM and TML of the PZT-5 piezoelectric vibrator has to be less than 0.1% and 1.0% respectively. Also, it has less than $500ng/cm^2/hr$ of TQCM for vacuum bake-out test using high temperature and high vacuum. Thus, the piezoelectric vibrator may be employed in the vacuum environments. Finally, it can be confirmed that the characteristics change of the piezoelectric vibrator is less than 1% under vacuum environments. Also, the temperature dependency of the characteristics in the PZT-5 piezoelectric vibrator with the lateral mode was investigated in the range of $-100^{\circ}C$ to $90^{\circ}C$ using the thermal vacuum chamber to utilize the vibrator to the aerospace industries. As the results, at room temperature, the resonant and anti-resonant frequencies had the minimum value, whereas, the dielectric constant increased linearly from about 2500 to 7500 in the given temperature range. The mechanical loss decreased linearly from 0.08 to 0.03.

• Journal of the Korea Institute of Building Construction
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• v.8 no.5
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• pp.93-99
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• 2008

The environment draws attention in the global community and a growing number of Koreans have interest in improving the quality of life, the importance of house environment has attracted the attention of the public. Against this backdrop, constructors have unveiled environmentally -friendly projects. However, they failed to establish people-oriented environment by being occupied with maximizing profitability through the improvement of brand image and caused sick house syndrome that has recently made controversy. In this regard, the study analyzed the mechanism of discharge of TVOC, one of the sick house syndrome-causing materials, that affects IAQ and its characteristics and examined the effect that granodiorite has on reduction of the discharge of TVOC in order to minimize damage. Experimental sample consisted of interior finishing materials frequently used in ceiling, wall and floor and adhesives used at a time of construction, and the TVOC of building materials was measured through the use of septum bottle unlike In the existing chamber method. Measures to counter the sick house syndrome were suggested by reducing the possible damage from the stage of selection of building material and by figuring out the effect that the granodiorite has on reduction of the discharge of TVOC.

• Land and Housing Review
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• v.4 no.4
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• pp.417-424
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• 2013

The purpose of this study was to investigate the characteristics of the indoor air quality by season. The surveyed houses were 48 new apartment complex in 2012 across the country. The houses were carried out the bakeout before the test. The measuring method was "Indoor air quality testing standards process" and the measured items were formaldehyde, benzene, toluene, ethylbenzene, xylene, styrene average emissions. All the items were more emitting during the summer. From June to September the average concentration of formaldehyde emission was higher than other seasons. The average emissions of benzene concentrations in all seasons were released in small quantities. Average emissions of toluene and ethylbenzene concentration from April to August showed slightly higher emissions. Xylene and styrene concentration showed the highest emissions at April, but without large deviations throughout the year.

• Journal of the Korean Vacuum Society
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• v.17 no.4
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• pp.270-277
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• 2008

Vacuum is any air or gas pressure less than a prevailing pressure in an environmental or, specifically, any pressure lower than the atmospheric pressure and is used by a wide variety of scientists and engineering - including clean environment, thermal insulation, very long mean free path, plasma, space simulation[1]. The space environment is characterized by such a severe condition as high vacuum, and very low and high temperature. Since a satellite will be exposed to such a space environment as soon as it goes into its orbit, space environmental test should be carried out to verify the performance of the satellite on the ground under the space environmental conditions. A general and widely used method to simulate the space environment is using a thermal vacuum chamber which consists of vacuum vessel and thermally controlled shroud. As indicated by name of vacuum chamber, the vacuum technology is applied to design and manufacture of the thermal vacuum chamber. This paper describe the vacuum technology which is applied to space business.