• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.25 no.3
• /
• pp.311-318
• /
• 2014

Electromagnetic compatibility(EMC) performance of the first Korea space launch vehicle(KSLV-I) should be ensured and verified in order to guarantee the normal operation among the spacecraft, ground facilities which are installed in the space center, and other wireless communication networks. For the purpose of the EMC performance verification, pertinent EMC test specifications, methods, and procedures for both the subsystems and the system should be established in consideration of operational properties and electromagnetic environmental effects. And it is required to maintain and control the EMC properties consistently in accordance with the determined specifications up to the program closing phase. In this paper, sequential management work conducted during the overall development process of the KSLV-I is explained, and not only the phased EMC test plan for each model of the KSLV-I and its subsystem but also test method, specification, and results of the verification tests are presented. And also, multipaction analysis results are presented.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.38 no.2
• /
• pp.195-199
• /
• 2010

(255,223) RS(Reed-Solomon) code which is the CCSDS(Consultative Committee for Space Data Systems) standard was used in the STSAT-3 to correct errors during the downlink of payload data. The RS encoder developed by VHDL was implemented in MMU(Mass Memory Unit). Moreover, the RS decoder developed by C-language was implemented in the DRS(Data Receiving System) of ground station. In this paper, we reported the design and analysis results of RS(255,223) for STSAT-3. The BER(Bit Error Rate) performance from MMU to DRS was confirmed through the downlink test at 16 Mbps. Also, the error correction performance and capability of RS(255,223) was tested by the manual attenuation of the RF(Radio Frequency) signal in the X-band transmitter resulting in putting some errors in the communication line.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.38 no.7
• /
• pp.702-708
• /
• 2010

Reaction wheel assemblies(RWA) are expected to be one of the largest high frequency disturbance sources to the optical payload of satellites. To ensure the tight pointing-stability budget and high image quality of satellites, a vibration isolation device should be applied to the main disturbances. For developing the isolating system, the disturbances need to be identified and modeled accurately. In the present study, a modeling technique of RWA and its disturbance was described. The micro-vibration disturbances were generated numerically by using an analytical wheel and disturbance model. The parameter estimation scheme of the model was suggested, and the RWA and disturbance modeling technique was verified through the numerical example analysis. The analytical results show that the wheel and disturbance model can be accurately established by using the modeling technique proposed in the present study. The wheel and disturbance model is expected to be useful for development of the RWA isolator system.

• Korean Journal of Remote Sensing
• /
• v.36 no.2_2
• /
• pp.231-236
• /
• 2020

Recently, great attention for environment changes of coastal regions due to climate change by the global warming has been raised. In addition, coastal environments which are very useful resources has been impacted by anthropogenic activities such as urbanization or fishery, etc. In situ measurements and remote sensing application using various platforms equipped by payloads with very diverse spectral resolution has been conducted to protect and reconstruct invaluable coastal region. In this special issue, several studies showing very interesting results of the coastal remote sensing in Korea. This special issue contains the research activities over the coastal regions in Korea has been performed by the KIOST Korea Ocean Satellite Center and academic organizations. We hope to share useful information on the various domestic coastal remote exploration activities and to contribute to develop scientific research to protect our invaluable coastal environment.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2006.05a
• /
• pp.197-202
• /
• 2006

The low-altitude earth observation satellite is generally equipped with high performance camera as a main payload which is vulnerable to vibration environment. During the launch process of a satellite, the combustion and jet noise of launch vehicle produce severe acoustic environment and the acoustic loads induced may damage the critical equipments of the satellite including the camera. Therefore to predict and simulate the effect of the acoustic environment which the satellite has to sustain at the lift-off event is very important process to support the load-resistive design and test-qualification of components. Statistical Energy Analysis(SEA) has been widely used to estimate the vibro-acoustic responses of the structures and gives statistical but reliable results in the higher frequency region with less modeling efforts and calculation time than the standard FEA. In this study, SEA technique has been applied to a 3-Dimensional model of a low-altitude earth observation satellite to predict the acceleration responses on the structural components induced by the high level acoustic field in the launch vehicle fairing. In addition, the expected response on each critical component panel was calculated by the classical method in consideration of the mass loading and imposed sound pressure level, and then compared with SEA results.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2012.02a
• /
• pp.105-105
• /
• 2012

본 논문에서는 전세계적으로 차세대 에너지절감 반도체로 각광을 받고 있는 GaN 소자의 연구개발 동향에 관하여 발표하고자 한다. GaN 반도체는 와이드 밴드갭(Eg=3.4eV)과 고온 안정성($700^{\circ}C$)등 재료적인 특징으로 인하여 고출력 RF 전력증폭기와 고전력용 전력반도체 응용에 큰 장점을 가진다. 고출력용 GaN RF 전력증폭 소자의 전력밀도는 기존 Si-기반 LDMOS 트랜지스터보다 10배 이상 높아 제품의 소형화와 경량화를 통하여 30% 이상의 전력절감이 가능하며, 레이더, 위성등 송수신 트랜시버 모듈에 GaN 전력증폭기를 이용할 경우 기존 GaAs-기반 전력증폭기에 비하여 높은 전력밀도(>x8)와 높은 효율(>20%)로 인하여 모듈 크기를 50% 이상 줄임과 동시에 경량화를 이룰 수 있어 비행기, 위성등 탑재체의 에너지 절감에 크게 기여할 수 있다. 고전력용 GaN 전력 스위칭 소자는 기존 Si-기반 IGBT에 비하여 스위칭 손실과 온-저항 손실이 낮아 30% 이상의 에너지 절감이 가능하다. 뿐만 아니라, 일본 도요타 자동차사의 보고에 의하면 HEV등 전기자동차의 DC-DC 부스터 컨버터나 DC-AC 인버터에 GaN 전력반도체를 적용할 경우 경량화, 변환효율 향상, 전용 냉각시스템을 제거할 수 있어 연료소모를 10% 이상 줄일 수 있어 연간 400불 이상의 에너지 절감 효과를 가진다. 이러한 에너지절감 효과는 미국, 유럽, 일본등 선진국을 중심으로 차세대 GaN 반도체의 신시장 개척과 선진입을 위한 치열한 경쟁 구도의 구동력이 될 것이며, 본 논문을 통하여 GaN 반도체의 연구개발 방향과 상용화의 중요성을 함께 생각해보고자 한다.

• Aerospace Engineering and Technology
• /
• v.3 no.1
• /
• pp.126-133
• /
• 2004

Photogrammetry, as its name implies, is a 3-dimensional coordinate measuring technique that uses photographs as the fundamental medium for metrology. In the last few years the accuracy of photogrammetry has increased dramatically thanks to the rapid advance of digital camera manufacturing technique. This paper discusses photogrammetric measurement of the interface surface of MSC(Multi-Spectral Camera), which is a main payload of KOMPSAT-2. Total 24 paper targets on the objective surfaces and two scale bars calibrated with high accuracy were used for measurement, and multiple images were taken from 11 different camera angles by using a spacecraft rotation dolly. As a result of analysis, 3D coordinates of each targeted point were obtained and the flatness value based on the selected reference plane was calculated and compared with the pre-determined requirement. The technique acquired by this study is expected to be used for the 3D precise measurement of ultra-light weight and inflatable space structures such as a satellite antenna and a solar array.

• Journal of Astronomy and Space Sciences
• /
• v.19 no.4
• /
• pp.283-292
• /
• 2002

Electronic boards of Far-ultraviolet IMaging Spectrograph (FIMS) should be designed to maintain their performances, and their temperatures should be remained within the allowed temperatures in operational environments. Thermal analysis at the electronic board level has been performed, and it is confirmed the electronics parts could be kept within their allowed temperature ranges.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.32 no.6
• /
• pp.134-141
• /
• 2004

The three-dimensional precision measurement technology for industrial product of middle and/or large scale has been developed. Theodolite measurement system which is one of the technology is widely used in aerospace industry. This paper describes a range alignment method of parabolic antenna to RF probe in the near field range by using the theodolite system, The range alignments of the Ku-band and Ka-band antennas have been accomplished within the requirements, ${\pm}1mm\;and\;{\pm}0.05^{\circ}$.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.46 no.4
• /
• pp.306-314
• /
• 2018

A two-axis gimbal-type X-band antenna for CAS(Compact Advanced Satellite) transmits large amount of image data to ground station regardless of satellite attitude and orbital motion. This antenna mounted on the external surface of the satellite is directly exposed to the extreme space with thermal environment during the orbital operation. Therefore, a proper thermal design is needed to maintain the antenna itself as well as other main components within allowable temperature range. In this study, the thermal design effectiveness of two-axis gimbal X-band antenna was verified through the thermal analysis. In addition, required power and duty cycle of heater were estimated through the thermal analysis under conditions of system level thermal vacuum test and on-orbit thermal environment. The thermal analysis results indicated that all the main components of X-band antenna satisfy the allowable temperature requirement.