• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.1
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• pp.69-75
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• 2016

This paper covers the result of construction and start-up tests of the KSLV(Korea Space Launch Vehicle)-II combustion chamber hot-firing test facility. This facility was constructed from 2012 to 2014. Start-up test of this facility began in the second half of 2014. Oxidizer cold flow test, fuel cold flow test and cooling water cold flow test were carried out as start-up test. Afterward, ignition test of combustion chamber was accomplished. The result of ignition test is applied to set up start-up sequence of KSLV-II combustion chamber and utilized as base line data for hot-firing test of low and normal design point.

• 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.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.4 s.119
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• pp.372-378
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• 2007

This paper presents an improvement of field uniformity in a reverberation chamber with QRDs(Quadratic Residue Diffuser) and also shows the optimal dimension of the QRDs. The QRD is designed for $1{\sim}3\;GHz$ frequency band and the FDTD(finite-Difference Time-Domain) method is used to analyze the field characteristics. At 2 GHz, the standard deviation of test volume in the reverberation chamber is the smallest when the QRD has $30{\sim}60\;%$ coverage of one side of the reverberation chamber and the field uniformity is worsened when the coverage of the QRD is either below 20 % or above 70 % of the area of the side wall. Particularly, the standard deviation of test volume in the reverberation chamber with 30 % coverage of QRD is improved by 1.53 dB compared to that of the reference chamber with no QRDs.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.12
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• pp.109-116
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• 2005

Elastic-plastic structural analysis for regenerative cooling chamber of liquid rocket thrust chamber is performed. Uniaxial tension test is also conducted for the copper alloy in order to get material data necessary for the structure analysis. The results of uniaxial tension test reveal that copper alloy become ductile after brazing process and flow stress becomes lower as temperature becomes higher. As a result of structural analysis using the material data, the deformation of cooling channel is more increased by thermal load than by internal pressure of cooling fluid. Therefore, the results of analysis show that structural stability and cooling performance of combustion thrust chamber which is designed to endure mechanical load and minimized a channel thickness are improved by decreased thermal load as possible.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.892-897
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• 2011

The propulsion system of space launch vehicle generates thrust by supplying oxidizer and fuel to combustion chamber. KSLV-II 2nd stage engine, currently under development by KARI, is to use liquid oxygen as a oxidizer and JET-A1 as a fuel. The 2nd stage pump-fed engine is mainly composed of combustion chamber, turbo-pump and engine supply system. To develop liquid propulsion engine, the development of combustion chamber must be preceded. For performance validation of the combustion chamber, the designed and manufactured combustion chamber should be tested in combustion chamber test facility(CCTF). The detailed design for the planned CCTF in Naro Space Center was conducted. The fuel supply system modeling using AMESim was performed based on the results of the detailed design, and the fuel supply characteristics was analyzed in this paper.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.12
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• pp.79-84
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• 2007

This paper presents an improved field uniformity in a reverberation chamber, that can be alternatively used for the analysis and the measurement of electromagnetic interference and immunity, with a designed CRD(Cubical Residue Diffuser) that have various dimensions. The Schroeder type CRD is designed for $1\sim3$ GHz band and the FDTD(Finite Difference Time Domain) method is used to analyze the field characteristics. At 2 GHz, the standard deviation of test volume in the reverberation chamber is the smallest and has a good field distribution with a CRD of $40\sim80%$ dimension of one side of the reverberation chamber. The Electric field uniformity gets worse when the dimension of a CRD is either below 40 % or above 80 % of the side wall. The result shows that the standard deviation of the test volume in the reverberation chamber with a CRD of 44 % dimension is improved by 1 dB compared with that of the reverberation chamber with a CRD of 100 % dimension.

• Analytical Science and Technology
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• v.20 no.4
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• pp.261-267
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• 2007

The 20 L small chamber test method is to evaluate pollutants such as TVOC, formaldehyde emitted from building materials. This method was only designed to evaluate the surface emission of sample exposed in the chamber. In this method, building materials cut with a fixed standard size are fixed in a sample sealing box. The sample sealing box is put into the 20 L test chamber. This chamber is ventilated at a standard air change rate with purified air for 7 days then the sample from the chamber is collected and analyzed to measure the emission rate of TVOC and formaldehyde. In this method, however, if the sealing box does not guarantee airtightness, accurate evaluation for the building materials can not be achieved due to the pollutants emitted from edge of the sample so called, edge effect. This edge effect can be much greater when evaluating panels such as plywood, flooring due to their surface treatment. In this study, flooring was tested to check airtightness of the sample sealing box with analytic results between 1L and 20 L test chamber. Furniture materials like LPM coated one side surface treatment and MDF coated both sides surface treatment with LPM were tested to identify whether the improvement of the sample sealing box airtightness is possible with the comparison between existing and improved test method that low VOC emission tape was used to seal the sample edge. After 7 days, MDF TVOC emission rate was different according to the existence and nonexistence of tape. The emission rate of the existing test method was $0.009mg/m^2h$ and that of improved test method was $0.003mg/m^2h$. Relative standard deviation for the existing test method was $0.004mg/m^2h$ and relative standard deviation for the improved test method was $0.002mg/m^2h$ when the same sample was analyzed three times. The improved test method in this study using low VOC emission tape was effective and able to reduce the heterogeneous effect of the edge from the sample sealing box.

• 한국연소학회:학술대회논문집
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• 2012.04a
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• pp.77-78
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• 2012

To predict combustion instability in actual full-scale combustion chamber of rocket engines, air-injection test is proposed with scaling techniques. From the data, damping factors have been obtained as a function of hydraulic parameter and the data give us instability map. Two instability regions are presented and it is found that they coincide reasonably with them from hot-fire test with full-scale flow rates. Accordingly, the proposed approach can be applied cost-effectively to stability rating of jet injectors when mixing of fuel and oxidizer jets is the dominant process in instability triggering.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2001.11a
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• pp.243-244
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• 2001

오존(O$_3$)은 성층권에서 태양광의 직접 지구 입사를 감소시키는 반면, 일반 대기 환경에서는 강력한 산화성과 더불어 최근 NOx, VOCs와의 연계성이 점차 밝혀지면서 최근 대기질 환경에 주요관심사가 되고 있다. 또한 지난 2000년 12개 도시에 52회의 0.3ppm이상의 고농도 오존 경보 발령으로 관리에 초점이 맞춰지고 있으나, 대기환경 중에서 자외선 등에 의한 2차 생성물질인 오존은 강력한 산화성으로 인해 표준물질이 없어 정확한 측정 및 관리에 어려움을 겪고 있다. (중략)

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.42-42
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• 2010

We, previously, proved that the noise in the vertical readback from some of beam position monitors (BPMs) in the vacuum chamber of Pohang Light Source (PLS) are caused by the transverse electric (TE) longitudinal harmonic resonances. Based on this analysis, we now design the shunt structure to remove the TE mode resonces near the BPMs operation frequency of 500 MHz in the storage ring vacuum chamber of PLS upgrade project (PLS-II). The simulation result and experimental test result will be presented.