• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.1057-1059
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• 2017

In development of liquid-propellant rocket engine, engine gimbaling requires various types of bellows movements and cryogenic insulation is applied with movement-based design and material on each axial and circular bellows. Cryogenic insulation of Bellows for high pressure line and recirculation line are necessary to maintain cryogenic temperature for engien efficiency and protect from heat transfer and radiation of high temperature components during engine gimbaling.

• Current Industrial and Technological Trends in Aerospace
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• v.7 no.2
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• pp.48-58
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• 2009

Since 1960s, cryogenic cooling technologies has been adopted in the development of spacecraft with components that must be cooled to cryogenic temperatures of 2 to 150 K. In recent years this technology has been a substantial growth in the emerging number of programs that include such spacecraft to service scientific, military, and weather observation missions. The cooling of optics and detectors to reduce signal noise in infrared (IR) telescopes is the principal applications of cryogenic cooling technologies. The choice of cooling technologies depends on the desired temperature level, the amount of heat to be removed, and the required operating life. This paper will present the status of modern cryogenic cooling technologies especially for space application.

• Composites Research
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• v.24 no.3
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• pp.39-45
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• 2011

Adhesive joints are widely used for structural joining applications in various fields and environmental conditions. Polyurethane (PU) and Epoxy adhesives are now being used for liquefied natural gas (LNG) carriers at cryogenic temperatures. This paper presents a comprehensive evaluation of epoxy and PU adhesive bonds between Triplex sheets at normal and cryogenic temperatures. The most significant result of this study is that for all adhesives tested, there is a significant decrease in peel strength at cryogenic temperatures. However, the reasons for the decrease in peel strength for epoxy and PU adhesives differ. Consequently, PU adhesives can be considered better suited for use in applications requiring high bonding performance at cryogenic conditions, such as in LNG carriers.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.309-312
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• 2007

The cryogenic fluid is the propellant for the liquid rocket engine. The design of space launcher vehicle is guided by minimum size and weight criteria, so the turbo pump solicits high impeller speed. Such high speed results in a zone of pressure drop below vapor pressure causing caivtation around inducer blades. The cryogenic fluid has different characters from isothermal fluid like water. The cryogenic fluid has very sensible thermodynamic properties and the phase change undergoes evaporative cooling. So, the developed code has to be modified cavitation modeling and it is added the energy equation for temperature sensitivity.

• Bulletin of the Korean Space Science Society
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• 2003.10a
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• pp.67-67
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• 2003

적외선 고감도천문관측 등 우주탑재체에서의 천문관측에서는 망원경 또는 관측용 센서를 4K 또는 그 이하로 냉각하여 고감도 관측을 하고 있다. 이와 관련하여 액체헬륨-4, 초유동헬륨, 액체헬륨-3, magnetic cooling 또는 dilution refrigeration 등의 방법으로 4K∼0.05K 영역까지의 극저온을 얻을 수 있다 우주탑재체에서의 극저온을 발생하는 방법과 본 연구실에서 개발 중인 ∼1K 까지의 극저온 발생장치의 설계 등에 관하여 논의한다.

• 기계와재료
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• v.21 no.4
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• pp.48-55
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• 2010

극저온에서 고분자 복합재료는 열전도도가 낮아 단열 특성이 탁월하고 전기절연성이 뛰어나 에너지 산업, 전기 및 전자산업, 생물공학, 의료분야, 수송산업, 우주 항공 산업 등 응용 범위가 매우 광범위하고, 산업 규모 또한 지속적으로 성장하고 있다. 향후 신재생 에너지의 저장 및 수송용으로 열전도도가 낮은 고분자 복합재에 대한 수요가 크게 증가할 것으로 예상된다. 따라서 본 고에서는 고분자 복합재료의 극저온 응용에 관한 국내외 기술동향과 수지 및 복합재 물성, 극저온에서의 특성 평가 기술 등에 대하여 소개하였다.

• Journal of the KSME
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• v.30 no.5
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• pp.460-469
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• 1990

극저온 냉동기술은 최첨단 산업에서 여러 방면에 걸쳐 실용화되고 있으며 상업화도 많이 되고 있다. 또한 앞으로의 응용범위는 더욱 확대될 전망이기 때문에 미래에 첨단 및 우주시대를 맞 이하여 국가주도 아래 적극적으로 육성 발전시키는 것이 절대적으로 필요하다고 본다. 본 내 용은 1989년에 과학기술처의 지원 하에 수행한 중점과제인 극한기술 분야 중 극저온 기술분야에 속하는 특정과제 "SQUID 냉각장치용 극저온 시스템 개발연구"의 일부분이다.t;의 일부분이다.

• Journal of the Korean Society of Propulsion Engineers
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• v.9 no.3
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• pp.66-73
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• 2005

The pressurization system in a liquid rocket propulsion system provides a controlled gas pressure in the ullage space of the vehicle propellant tanks. It is advantage to employ a hot gas heat exchanger in the pressurization system to increase the specific volume of the pressurant and thereby reduce over-all system weight. A significant improvement in pressurization-system performance can be achieved, particularly in a cryogenic system, where the gas supply is stored inside the cryogenic propellant tank. In this study liquid nitrogen was used instead of liquid oxygen as a simulant. The temperature characteristic of cryogenic pressurant is very important to develop some components in pressurization system. Numerical modeling and test data were studied using SINDA/FLUINT Program and PTF(Propellant-feeding Test facility).

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.4
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• pp.391-397
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• 2010

Performance tests of a liquid-oxygen pump were carried out using liquid nitrogen (LN2) as a working fluid in a cryogenic turbopump test facility in Korea Aerospace Research Institute (KARI). The tests were performed at 30-55% of the design rotational speed, and the results were compared with those from a water test. The experimental results confirmed the similarity of the hydraulic performance, which allows the prediction of the pump performance at a design rotational speed of 20,000 rpm. The overall cavitation performance of the pump in the cryogenic environment was better than that in the water environment for all ranges of flow rates and rotational speeds. Critical cavitation number at the design flow rate was determined as 0.012 from the cryogenic test, and as 0.024 from the water test. The improved cavitation performance is due to the thermodynamic effect in cryogenic fluids.

• KEPCO Journal on Electric Power and Energy
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• v.2 no.2
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• pp.299-305
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• 2016

The High Temperature Superconducting power cables (HTS power cables) become increasingly longer to commercialize the HTS power cable system. Accordingly, demands on refrigerators of large cooling capacity per a unit system have been increased. In Korea, it is currently imported from abroad with the high price due to insufficient domestic technologies. In order to commercialize the HTS power cables, it is necessary to develop the refrigerators with large cooling capacity. The Brayton refrigerators are composed of recuperative heat exchangers, compressors and cryogenic turbo expanders. The most directly considering the efficiency of the Brayton refrigerator, it depends on performance of the cryogenic turbo expander. Rotating at high speed in cryogenic temperature, the cryogenic turbo expanders lower temperature by expanding high pressure of a helium or neon gas. In this paper, the reverse Brayton cycle is designed and the cryogenic turbo expander is designed in accordance with the thermodynamic cycle.