• Aerospace Engineering and Technology
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• v.10 no.1
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• pp.70-78
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• 2011

The Equations of inherent flow coefficient are different from compressible to incompressible flow. The paper has been conducted to measure the inherent flow coefficient of solenoid valve under various flows. Experimental results for compressible and incompressible flow were confirmed to inherent flow coefficient correctly. The value of inherent flow coefficient for the 0.5" solenoid valve is about 2. Dynamic characteristics of a solenoid valve, which plays an important role in real model, have been analysed by AMESim simulator modeling.

• Aerospace Engineering and Technology
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• v.12 no.1
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• pp.182-188
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• 2013

This paper described flight safety center, flight safety information system(FSIS) and flight safety officer's mission and training in sequence and presented analysis's results and data processed in real-time during KSLV-I 3rd flight test. During flight safety center's operation for the 3rd flight test, monitoring of KSLV-I flight status was normally performed and the algorithms for flight safety calculations including the one for instantaneous impact point computations are also executed normally.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.103.1-103.1
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• 2013

위성의 발사, 천이궤도, 운영궤도 등에서 위성체에 주어지는 극한 온도와 진공상태에서 위성체와 열 제어시스템이 요구 조건을 만족시키는가를 확인하기 위하여 열진공시험을 수행한다. 열진공시험은 기본적으로 고진공 환경 하에서 심우주의 극저온 온도 모사가 가능해야 한다. 현재 산업용으로 일반적으로 사용하고 있는 냉동기의 경우는 최저 $-70^{\circ}C$ 까지 도달 가능하므로 심우주모사에 적당하지 않아, 주로 액체질소 및 기체질소를 이용한 냉각장치를 사용하고 있다. 본 논문에서는 진공하에서 심우주의 극저온 및 고온의 열환경을 모사할 수 있는 방법 및 장치의 개념 설계에 대해 알아보고자 한다.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.513-513
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• 2015

정확한 유역 토양수분 정보는 홍수 예측의 정도를 크게 향상시키므로 공간 토양수분 정보를 획득하기 위하여 선진국에서는 위성 영상을 활용하여 토양수분을 관측하고 있다. 본 연구에서는 유럽우주기구 ESA(European Space Agency)에서 운영하는 SMOS(Soil Moisture and Ocean Salinity) L-band 토양수분 관측치와 일본 우주항공 연구개발 기구 JAXA(Japan Aerospace Exploration Agency)에서 운영하는 GCOM-W1 위성의 AMSR2(Advanced Microwave Scanning Radiometer 2) C-band 토양수분 자료를 비교 분석하였다. SMOS 토양수분, AMSR2 토양수분을 기상청 농업관측관서의 지상 관측 토양수분 자료와 비교한 그래프는 다음과 같다(Fig. 1). 상대적으로 깊은 관측심으로 인한 장점을 가짐에도 불구하고 RFI로 인한 L-band 토양수분 자료의 시공간 관측율이 C-band 토양수분자료에 비하여 낮아 활용성이 낮다. AMSR2 자료는 여름철을 제외한 모든 계절에 과소 추정하는 단점을 보이며 실제적 활용을 위해 지상자료와의 편이보정 과정이 필수적이라 판단된다.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.05a
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• pp.240-243
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• 2003

Finite element analyses for bursting failure prediction in bulge forming under combined internal pressure and independent axial feeding are carried out. By means of the FEM combined with Oyane's ductile fracture criterion based on Hills quadratic plastic potential, the forming limit and bursting pressure level are investigated for a seamed tube that comprises of weldment, heat affected zone(HAZ) and base material parts. Especially, in order to determine the material property of HAZ tensile tests for the base material and the weld metal are executed based on iso-strain approach. Finally, through a series of bulge forming simulations with consideration of the weldment and HAZ it is concluded that the proposed method would be able to predict the bursting pressure and fracture initiation site more realistically, so the approach can be extended to a wide range of practical bulge forming processes.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.12
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• pp.1018-1024
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• 2013

On-Board computers (OBC) for LEO & GEO satellites have been developed with their own dedicated architecture so far even though they have many similar functionalities. In this paper, we present a conceptual study results of standard OBC architecture design and propose the domestic development plan for the next generation satellite OBC. Proposed architecture is highly flexible and can be used at LEO/MEO/GEO and Moon Explorer/Deep Space Probe. Also, we introduce current status of standard OBC which is under development.

• Journal of Advanced Navigation Technology
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• v.27 no.6
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• pp.690-698
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• 2023

Information sharing and decision making between airport stakeholders became possible after the introduction of airport cooperative making system (A-CDM). This also resulted in optimizing aircraft handling time and increased the efficiency of aircraft operations. Technological advances have recently led to the development of urban air mobility (UAM) which is a small aircraft taking off and landing vertically. It is emerging as a new air transportation system in the future due to its advantage of saving time and solving congestion problem in the urban area. This study aims to suggest how vertiport cooperative decision making system (V-CDM) should be managed for efficient operation of UAM. By establishing procedure for decision making system based on Vertiport ecosystem of UAM. By establishing procedure for decision making system based on Vertiport ecosystem and UAM aircraft, unnecessary flight delays or cancellations can be minimized and efficiency of UAM operation will be improved as well.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.2
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• pp.156-165
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• 2015

A survivability-analysis program has been developed to analyze the ground collision risk of atmospheric reentry objects, such the upper stages of a launch vehicle or satellites, which move at or near the orbital velocity. The aero-thermodynamic load during the free fall, the temperature variation due to thermal load, and the phase shift after reaching the melting point are integrated into the 3 degree-of-freedom trajectory simulation of the reentry objects to analyze the size and weight of its debris impacting the ground. The analysis results of the present method for simple-shaped objects are compared with the data predicted by similar codes developed by NASA and ESA. Also, the analysis for actual reentry orbital objects has been performed, of which results are compared with the measurement data.

• Journal of Space Technology and Applications
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• v.3 no.1
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• pp.58-71
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• 2023

This paper describes a navigation system design for horizontal position estimation using inertial measurement sensors and celestial navigation. In space, stars are widely spread objects in the celestial sphere and have been used mainly to obtain attitude information through star observation. However, it is also possible to obtain information about the horizontal position with the altitude of the star. It is called celestial navigation which is the same principle that former navigators used to locate themselves while sailing on the sea. In particular, in deep space where GPS is not available, it is important to obtain information on the location by making use of stars that are relatively easy to observe. Therefore, we introduce a navigation system that can estimate horizontal position and design two types of systems, loosely coupled and tightly coupled depending on how the measurements are utilized. It is intended to help in the future design of navigation system using celestial navigation by simulation studies that not only verify whether the system correctly estimates horizontal position but also comparing the performance of loosely and tightly coupled methods.

• The Science & Technology
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• v.16 no.5 s.168
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• pp.8-21
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• 1983

- 유가 인하분 과학기술개발 특별자금으로 - 유전공학 연구현황과 육성방향(유전공학 학술협, 심포지움 가져) - 태평양지역 화학공학 학술대회 개최(5월6일~14일, 24개국 1천여명 참가) - '83 우주과학 박람회 개막(6월15일까지 아폴로 캡슐 등 공개) - 스웨덴 ASEA-ATOM사 간부진 민관식 과총회장 예방 - 세계 최장 광섬유 시스템 미 벨사 통신실험에 성공