• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.12
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• pp.90-95
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• 2006

The wall of thermal vacuum chamber which is used for the satellite thermal balance test doesn't absorb satellite's IR emission perfectly and reflects some part of that. It is estimated that small thermal vacuum chamber has relatively larger wall effect than the big one. The small thermal vacuum chamber is required for the small satellite test to reduce the test cost. A quantitative analysis was carried out to investigate the chamber wall effect. As a result, temperature errors caused by chamber wall effect was calculated, and the temperature data acquired in the thermal balance test have been compensated. By defining the optimized area ratio between chamber surface and satellite surface area, the baseline to be able to determine the minimum size of thermal vacuum chamber was established to minimize the wall effect. Also, theoretical analysis about transparent material coating which can reduce the chamber wall effect is conducted.

• Geotechnical Engineering
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• v.11 no.2
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• pp.19-28
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• 1995

Based on the various test data acquired in the field, the large pressure chamber and the small pressure chamber, uplift behaviors and method of determining the ultimate uplift capacity of pile driven in small pressure chamber were studied. After uplift pile experienced 2 or 3 sudden slip due to increase of uplift load, complete pullout failure was occurred. Thus, it appears that the ultimate uplift capacity could be identified as the load at displacement where first slip occurs. The ultimate uplift capacity might be determined in every test and the disturbance after first uplift test could be recovered by adding one blow of the drop hammer, which had to depend on the model pile capacity.

• Journal of the Korean Solar Energy Society
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• v.26 no.3
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• pp.99-110
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• 2006

This study focused on the emission rate of the construction materials. The method of study is as follows. First, validation of small chamber method to determine emission rate of construction material was performed by CFD simulation. For the result of this study, uniform air velocity in small chamber was founded, and small chamber as a test material for emission rate was validated. Second, the construction materials were categorized by their feature and the emission rate of volatile organic compound was determined. Totally, VOCs emission rate of 49 materials were determined.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.7
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• pp.563-570
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• 2006

We investigated the emission characteristics of gaseous organic contaminants from building materials and newly constructed apartments. The emission test for building materials was done with small chamber method, and field measurements in newly constructed apartment were carried out by Korea Standard Test Method for Indoor Air Quality. First, the emission test by small chamber showed that the TVOC emission from building materials was much higher than formaldehyde. On the other hand, as expected, considerably high concentration of both TVOC and HCHO was detected in the new apartment.

• The Journal of the Korea Contents Association
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• v.15 no.12
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• pp.1-7
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• 2015

These anti-jamming GPS systems are verified using large anechoic chamber or field-test until now. When using a large anechoic chamber, Independent verification from external enviroments like noise is an advantage but high cost and availability of chamber are disadvantages. And in case of field test, verification under real propagation enviroment is an advantage but security problem of military equipments and problem of making same test condition are disadvantages. This paper presents an newly developed anti-jamming GPS test system. This test system mainly consists of small anechoic chamber, jamming divider, jamming signal generator and satellite simulator. The small anechoic chamber is installed many jamming antennas to transmit multi jamming signals and the jamming divider is newly developed to control multi jamming signals. According to self performance test and combined test with Anti-jamming GPS receiver, we verified our system's reliability.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.5
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• pp.407-415
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• 2021

The performance of satellite parts must be verified under the space orbit environment before the launch. This paper develops a model formula considering the thermal environment such as conduction, radiation, heat loss and internal heating between satellite parts and a small thermal vacuum chamber for thermal vacuum tests. System identification is carried out using test data from 20 recent thermal vacuum tests conducted by the Korea Aerospace Research Institute. It is verified that the model formula and the identification results are valid, except when the heating of the functional test of the test specimen is not constant.

• Journal of IKEEE
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• v.16 no.4
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• pp.290-296
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• 2012

In this study, an effective echo-suppression and cancellation technique using reflectors in semi-anechoic chamber and time-domain measurement is proposed. By using the proposed technique, the uniformity of electric field in QZ(Quiet Zone) could be improved and the antenna test environments similar to the fully anechoic chamber could be accomplished. The performances of the proposed test environments is verified with the simulated and measured data. And it is demonstrated that this test environment is possible to use the measuring the radiational characteristics of a small antenna in VHF band.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.134-138
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• 2005

The structural analysis and water pressure test of regenerative liquid rocket thrust chamber cooling channel specimens are performed at room temperature. material properties of copper alloy are obtained by uniaxial tension test at room temperature and used of elastic-plastic structural analysis. The plate type of cooling channel specimen are manufactured and performed water pressure test in order to confirm the analysis results. The differences between results of elastic-plastic analysis and that of water pressure test of cooling channel specimen are small and find that manufacturing process affect the structural stability of cooling channel very much because cooling channel thickness is small

• Journal of Environmental Health Sciences
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• v.43 no.2
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• pp.95-102
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• 2017

Objectives: This study was conducted to evaluate the emission of VOCs from clothing that had been dry cleaned. Methods: In order to ensure the same conditions, f100% wool scarves were selected as the fabric type. Four identical tests were conducted on the option of either removing the plastic bags which came from the dry cleaning shop or not. The scarf was located inside a closet or room for one or two days. Small chamber tests were conducted to determine the VOC emission characteristics under the same conditions such as temperature, humidity, loading factor, and air exchange rates. Air from the chamber for VOCs was sampled by Tenax TA tube and analyzed by thermal desorption and GC/MSD. Results: Assuming that test represented dry cleaning and consumer's conditions well enough, we can conclude that immediate emissions after the dry cleaning of the scarfs caused elevated levels of TVOC, five VOCs (benzene, toluene, ethylbenzene, xylene, stylene), and decane group compounds. Conclusions: By removing the plastic bags which came from the dry cleaning shop or not, the storage conditions of dry cleaned scarfs by consumers during the storage time periods (one to three days) would be significant for reducing VOC emissions.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.33 no.2
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• pp.145-155
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• 2023

Objectives: A fit test panel is needed to identify the fit performance of a respirator and its face seal. This is a criterion for selecting subjects that can represent the facial characteristics of users. Although anthropometry data has been developed for people in United States and China it is not yet present in Korea. This study aimed to develop a Korean fit test panel and test headform. Methods: For the 7th and 8th waves of the Size Korea anthropometry data, facial measurements of 11,429 people aged 15 to 69 years were used for analysis. PCA and bivariate panel were classified using the ISO16976-2:2022(E) anthropometrics analysis method. Based on this result, a static headform was developemed and a fit test chamber was constructed. Results: Of the 11,429 Korean people used for principal component analysis, 11,300 were included in the ellipse, marking an acceptance rate of 98.87% on PCA panel. The face types were classified into five types. Among them, a large, medium, and small static headform were printed using a 3D printer. In addition, 10,985 people (96.12%) were included in the bivariate panel based on face length and face width. The y-axis (face length) boundary was 97.87 to 134.59 mm, and the x-axis (face width) boundary was 120.75 to 158.23 mm. Conclusions: Compared to the ISO analysis, the Korean principal component was narrower in the width item (PC1) and longer in the length item (PC2). For the future, it is necessary to conduct a fit test using the developed headform and chamber device to confirm the usefulness of this Korean test panel. Therefore, this study is considered valuable as basic research for Korean test panels.