• Title/Summary/Keyword: Orbit control

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The Interface Test between LEO Satellite and Ground Station (저궤도위성과 지상국 간 접속 검증 시험)

  • Kwon, Dong-Young;Jung, Ok-Chul;Kim, HeeSub
    • Aerospace Engineering and Technology
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    • v.11 no.2
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    • pp.49-56
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    • 2012
  • LEO Satellite performs the operations and missions by FSW(Flight Software) after separation from a launch vehicle. Many of the operations by FSW are automatically conducted by the algorithms of FSW. In the case of the IAC(Initial Activation and Checkout) operations, a mission scheduling, an orbit transition, etc, however, a decision and a control of the satellite operators or manufacturers are required in order to operate the satellite safely. For this, the wireless communication channel between a satellite and a ground station should be prepared to receive telemetries and to transmit tele-commands for controlling FSW properly. Therefore, the verification of the interface between KOMPSAT-3 and a ground station is essential. This verification test is named the satellite end-to-end test. In this paper, we show the design process of the satellite end-to-end test and test results.

The Merits of Mannitol in the Repair of Orbital Blowout Fracture

  • Shin, Kyung Jin;Lee, Dong Geun;Park, Hyun Min;Choi, Mi Young;Bae, Jin Ho;Lee, Eui Tae
    • Archives of Plastic Surgery
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    • v.40 no.6
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    • pp.721-727
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    • 2013
  • Background One of the main concerns in orbital blowout fracture repair is a narrow operation field, due mainly to the innate complex three dimensions of the orbit; however, a deep location and extensive area of the fracture and soft tissue edema can also cause concern. Swelling of the orbital contents progresses as the operation continues. Mannitol has been used empirically in glaucoma, cerebral hemorrhage, and orbital compartment syndrome for decompression. The authors adopted mannitol for the control of intraorbital edema and pressure in orbital blowout fracture repair. Methods This prospective study included 108 consecutive patients who were treated for a pure blowout fracture from January 2007 to October 2012. For group I, mannitol was administered during the operation. Under general anesthesia, all patients underwent surgery by open reduction and insertion of an absorbable mesh implant. The authors compared postoperative complications, the reoperation rate, operation time, and surgical field improvement between the two groups. Results In patients who received intraoperative administration of mannitol, the reoperation rate and operation time were decreased; however, the difference was not statistically significant. The total postoperative complication rates did not differ. Panel assessment for the intraoperative surgical field video recordings showed significantly improved vision in group I. Conclusions For six years, mannitol proved itself an effective, reliable, and safe adjunctive drug in the repair of orbital blowout fractures. With its rapid onset and short duration of action, mannitol could be one of the best methods for obtaining a wider surgical field in blowout fracture defects.

Ground Vibration Test for Korea Sounding Rocket - III (KSR-III의 전기체 모달 시험)

  • 우성현;김영기;이동우;문남진;김홍배
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.05a
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    • pp.441-447
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    • 2002
  • KSR-III(Korea Sounding Rocket - III), which is being developed by Space Technology R&D Division of KARI(Korea Aerospace Research Institute) will be launched in late 2002. It is a three-stage, liquid propellant rocket which can reach 250 km altitude and will carry out observation of ozone layer and scientific experiments, such as microgravity experiment, and atmospheric measurement. KSR-III is believed to be an intermediate to the launch vehicle capable of carrying a satellite to its orbit. Space Test Department of KARI performed GVT(Ground Vibration Test) fer KSR-III EM at Rocket Test Building of KARI. GVT is very important for predicting the behavior of rocket in its operation, developing flight control program and performing aerodynamic analysis. This paper gives an introduction of rocket GVT configuration and information on test procedures, techniques and results of It. In this test. to simulate free-free condition, test object hung in the air laterally by 4 bungee cords specially devised. For the excitation of test object, pure random signal by two electromagnetic shakers was used and total 22 frequency response functions were achieved. Polyreference parameter estimation was performed to identify the modal parameters with MIMO(Multi-Input-Multi-Output) method. As the result of the test, low frequency mode shapes and modal parameters below 60Hz were identified

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Performance and Thermal Design Validation for FM STEP Cube Lab. (큐브위성 STEP Cube Lab. 비행 모델의 열진공시험을 통한 성능 및 열제어계 설계 검증)

  • Kang, Soo-Jin;Jung, Hyun-Mo;Seo, Joung-Ki;Oh, Hyun-Ung
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.43 no.9
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    • pp.814-821
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    • 2015
  • The STEP Cube Lab. classified as a pico-class satellite has been successfully developed as a flight model(FM) to be launched in 2015. Its mission objective is to perform the on-orbit verification of fundamental space core-technologies. In this study, a thermal design concept based on the passive method to achieve the mission objective is introduced. The effectiveness of the thermal design and performance of the satellite has been verified through the acceptance level thermal vacuum test. In addition, to improve the reliability of thermal mathematical model, correlation was performed using the results of thermal balance test. This paper describes a series of process for the thermal vacuum test on the STEP Cube Lab. FM.

Development of Space Divided PE-ALD System and Process Design for Gap-Fill Process in Advanced Memory Devices (차세대 메모리 디바이스Gap-Fill 공정 위한 공간 분할 PE-ALD개발 및 공정 설계)

  • Lee, Baek-Ju;Hwang, Jae-Soon;Seo, Dong-Won;Choi, Jae-Wook
    • Journal of Surface Science and Engineering
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    • v.53 no.3
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    • pp.124-129
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    • 2020
  • This study is for the development of high temperature ALD SiO2 film process, optimized for gap-fill process in manufacturing memory products, using a space-divided PE-ALD system equipped with an independent control dual plasma system and orbital moving unit. Space divided PE-ALD System has high productivity, and various applications can be applied according to Top Lid Design. But space divided ALD system has a limitation to realize concentric deposition map due to process influence due to disk rotation. In order to solve this problem, we developed an orbit rotation moving unit in which disk and wafer. Also we used Independent dual plasma system to enhance thin film properties. Improve productivity and film density for gap-fill process by having deposition and surface treatment in one cycle. Optimize deposition process for gap-fill patterns with different depths by utilizing our independently controlled dual plasma system to insert N2and/or He plasma during surface treatment, Provide void-free gap-fill process for high aspect ratio gap-fill patterns (up to 50:1) with convex curvature by adjusting deposition and surface treatment recipe in a cycle.

Instrumentation and system identification of a typical school building in Istanbul

  • Bakir, Pelin Gundes
    • Structural Engineering and Mechanics
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    • v.43 no.2
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    • pp.179-197
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    • 2012
  • This study presents the findings of the structural health monitoring and the real time system identification of one of the first large scale building instrumentations in Turkey for earthquake safety. Within this context, a thorough review of steps in the instrumentation, monitoring is presented and seismic performance evaluation of structures using both nonlinear pushover and nonlinear dynamic time history analysis is carried out. The sensor locations are determined using the optimal sensor placement techniques used in NASA for on orbit modal identification of large space structures. System identification is carried out via the stochastic subspace technique. The results of the study show that under ambient vibrations, stocky buildings can be substantially stiffer than what is predicted by the finite element models due to the presence of a large number of partitioning walls. However, in a severe earthquake, it will not be safe to rely on this resistance due to the fact that once the partitioning walls crack, the bare frame contributes to the lateral stiffness of the building alone. Consequently, the periods obtained from system identification will be closer to those obtained from the FE analysis. A technique to control the validity of the proportional damping assumption is employed that checks the presence of phase difference in displacements of different stories obtained from band pass filtered records and it is confirmed that the "proportional damping assumption" is valid for this structure. Two different techniques are implemented for identifying the influence of the soil structure interaction. The first technique uses the transfer function between the roof and the basement in both directions. The second technique uses a pre-whitening filter on the data obtained from both the basement and the roof. Subsequently the impulse response function is computed from the scaled cross correlation between the input and the output. The overall results showed that the structure will satisfy the life safety performance level in a future earthquake but some soil structure interaction effects should be expected in the North South direction.

Application of Cost Estimation to Space Launch Vehicle Development Program (우주발사체 개발사업의 비용 추정 현황 및 사례)

  • Yoo, Il-Sang;Seo, Yun-Kyoung;Lee, Joon-Ho;Oh, Bum-Seok
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.30 no.3
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    • pp.165-173
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    • 2007
  • A space launch vehicle system represents a typical example of large-scale multi-disciplinary systems, consisting of subsystems such as mechanical structure, electronics, control, telecommunication, propulsion, material engineering etc. A lot of cost is required to develop the launch vehicle system. A precise planning of R&D cost is very essential to make a success of the launch vehicle development program. Especially in the early development phase of a new space launch vehicle system, cost estimation techniques and analogy from past similar development data are very useful methods to estimate a development cost of the launch vehicle system. Now Korea Aerospace Research Institute is in charge of the KSLV-I (Korea Space Launch Vehicle-I) Program that is a part of Korea National Space program. KSLV-I Program is a national undertaking to develop launch capabilities to deliver science satellites of a 100kg-class into a low earth orbit. It is hereafter, going to plan to develop a new korean space launch vehicle. In this paper, first the development costs of well-known launch vehicles in the world are presented to provide a reference to make a development plan of a new launch vehicle. Second this paper introduces the present status of cost estimation applications at NASA. Finally this paper presents the results from application of a TRANSCOST, a parametric cost model, to derive a cost estimate of a new launch vehicle development, as an example.

Estimating Fatigue Life of APD Electronic Equipment for Activation of a Spaceborne X-band 2-axis Antenna (2축 짐벌식 X-band 안테나 구동용 전장품 APD 제어보드의 피로수명 평가)

  • Jeon, Young-Hyeon;Oh, Hyun-Ung
    • Journal of Aerospace System Engineering
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    • v.11 no.1
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    • pp.1-7
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    • 2017
  • While a satellite is carried into orbit by a launch vehicle, it is exposed to the severe launch environment with random vibrations and shock. Accordingly, these vibration sources affect electronic equipment, particularly the printed circuit board (PCB) in the satellite. When the launch load impacts the PCB, it causes negative behavior. This causes perpendicular bending around the boundary of fixation points that finally leads to the failure of solder joints, lead wires, and PCB cracks. To overcome these issues, the electronic equipment design must meet reliability requirements. In this paper, Steinberg's method is used to derive allowable and maximum deflection to verify design from a life perspective concerning the control board of the Antenna Pointing Driver (APD) mounted on KOMPSAT-3.

Regulated Peak Power Tracking (RPPT) System Using Parallel Converter Topologies

  • Ali, Muhammad Saqib;Bae, Hyun-Su;Lee, Seong-Jun;Cho, Bo-Hyung
    • Journal of Power Electronics
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    • v.11 no.6
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    • pp.870-879
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    • 2011
  • Regulated peak power tracking (RPPT) systems such as the series structure and the series-parallel structures are commonly used in satellite space power systems. However, these structures process the solar array power or the battery power to the load through two cascaded regulators during one orbit cycle, which reduces the energy transfer efficiency. Also the battery charging time is increased due to placement of converter between the battery and the solar array. In this paper a parallel structure has been proposed which can improve the energy transfer efficiency and the battery charging time for satellite space power RPPT systems. An analogue controller is used to control all of the required functions, such as load voltage regulation and solar array stabilization with maximum power point tracking (MPPT). In order to compare the system efficiency and the battery charging efficiency of the proposed structure with those of a series (conventional) structure and a simplified series-parallel structure, simulations are performed and the results are analyzed using a loss analysis model. The proposed structure charges the battery more quickly when compared to the other two structures. Also the efficiency of the proposed structure has been improved under different modes of solar array operation when compared with the other two structures. To verify the system, experiments are carried out under different modes of solar array operation, including PPT charge, battery discharge, and eclipse and trickle charge.

Construction of a Thermal Vacuum Chamber for Environment Test of Triple CubeSat Mission TRIO-CINEMA

  • Jeon, Jeheon;Lee, Seongwhan;Yoon, Seyoung;Seon, Jongho;Jin, Ho;Lee, Donghun;Lin, Robert P.
    • Journal of Astronomy and Space Sciences
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    • v.30 no.4
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    • pp.335-344
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    • 2013
  • TRiplet Ionospheric Observatory-CubeSat for Ion, Neutron, Electron & MAgnetic fields (TRIO-CINEMA) is a CubeSat with 3.14 kg in weight and 3-U ($10{\times}10{\times}30$ cm) in size, jointly developed by Kyung Hee University and UC Berkeley to measure magnetic fields of near Earth space and detect plasma particles. When a satellite is launched into orbit, it encounters ultra-high vacuum and extreme temperature. To verify the operation and survivability of the satellite in such an extreme space environment, experimental tests are conducted on the ground using thermal vacuum chamber. This paper describes the temperature control device and monitoring system suitable for CubeSat test environment using the thermal vacuum chamber of the School of Space Research, Kyung Hee University. To build the chamber, we use a general purpose thermal analysis program and NX 6.0 TMG program. We carry out thermal vacuum tests on the two flight models developed by Kyung Hee University based on the thermal model of the TRIO-CINEMA satellite. It is expected from this experiment that proper operation of the satellite in the space environment will be achieved.