• Aerospace Engineering and Technology
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• v.1 no.1
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• pp.177-187
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• 2002

Some kinds of precision optical systems for spaceborne high resolution cameras were designed at preliminary design level and an optical design for a hyperspectral imager was performed for its development model. A Cassegrain-based catadioptric system and an unobscured reflective triplet system are illustrated in detail for spaceborne high resolution electro optical cameras which have performance of 5m resolution at an altitude of 685km and the design are evaluated in its spot-diagram and MTF to prove they have good performance enough to implement the requirements for realistic satellite payload taking the fabrication conditions and the on-orbit operation into consideration. For the development of hyperspectral imager as a next-generation payload, an optical system has been designed and elaborated. It can be divided into two parts, a catoptric telescope forming an off-axis 2 mirror type and a dispersive spectrometer which comprises collimator, grating and reimaging lens cell. From its optical design to the system characteristics are shown with the MTF performance reaching 25% approximately.

• Journal of Aerospace System Engineering
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• v.11 no.2
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• pp.30-34
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• 2017

This paper is concerned with product assurance for the secondary payload, which is used for technology and science research, in the satellite system, which consists primarily of the spacecraft and the primary payload (a high-resolution optical camera). The Korean satellite development program has successfully insured the safety of the spacecraft and primary payload. However, given the limits of budget and schedule, it is very important to establish adequate product assurance for the secondary payload, which has a lower priority than the spacecraft or primary payload. This paper studies the concept of product assurance for the secondary payload of technological and scientific equipment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.10B
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• pp.1777-1784
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• 2000

In this paper we suggested the chirp stitching algorithm and transmitter/receiver channel to a spaceborne high resolution SAR which enables wideband signal generation and processing with minimum hardware requirement. The transmitter channel generates two sub-band signals and then generate a wideband signal using chirp stitching algorithm and the receiver channel divides a wideband signal into two sub-band signals in order to overcome the high speed data handling capability of this spaceborne systems. We generated and processed a 100 MHz wideband signal evaluated the performance and verified the feasibility of the application of this chirp stitching algorithm and transmitter/receiver channel to spaceborne high resoultion SAR.

• Journal of Advanced Navigation Technology
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• v.10 no.2
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• pp.173-180
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• 2006

An airborne radar is an essential aviation electronic system of the aircraft to perform various missions in all weather environments. This paper presents the design, development, and test results of the multi-mode pulsed Doppler radar system test model for helicopter-borne flight test. This radar system consists of 4 LRU units, which include ANTU(Antenna Unit), TRU(Tx Rx Unit), RSDU(Radar Signal & Data Processing Unit) and DISU(Display Unit). The developed technologies include the TACCAR processor, planar array antenna, TWTA transmitter, coherent I/Q detector, digital pulse compression, DSP based Doppler FFT filtering, adaptive CFAR, IMU, and tracking capability. The design performance of the developed radar system is verified through various helicopter-borne field tests including MTD (Moving Target Detector) capability for the Doppler compensation due to the moving platform motion.

• Aerospace Engineering and Technology
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• v.10 no.1
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• pp.107-115
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• 2011

The line-telemetry data processing system is necessary for monitoring the status of each onboard systems of KSLV-I upper stage during the ground tests and launch preparation. The mission of line-telemetry system is to provide reference telemetry data and to monitor the status of upper stage. The line-telemetry data processing system consists of a PCM acquisition/processing server, a system management server, and 9 monitoring consoles. In this paper, we will describe the overview of onboard remote measurement system, the design of the line-telemetry data processing system, anomaly setup information for indicating alarm signal in case of abnormal occurrence, and the result of the ground test and flight test.

• Aerospace Engineering and Technology
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• v.12 no.2
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• pp.173-179
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• 2013

This paper describes a testbed that was designed and implemented for the development of KSLV-II onboard equipment simulator. It used the CPCI-based industrial hardware system for scalability and the QNX real-time operating system for reliability and real-time simulation. In addition, a real-time application under QNX for function simulations of the KSLV-I PDU was developed and it was verified through interface experiments with KSLV-I upper-stage test equipment. The implemented simulator testbed will be used to verify the development feasibility in the design and development phase of a real KSLV-II onboard equipment simulator.

• Proceedings of the KWS Conference
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• 2010.05a
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• pp.52-52
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• 2010

선박건조에 있어서 대형 블록의 조립이 이루어지는 선행 탑재 및 탑재 단계에서 Tank Top과 Upper Deck의 V 개선 용접은 FCAW+SAW의 복합용접이 실시되고 있다. 그러나 가장 범용적 모재 두께인 18~20t의 경우 SAW 시공에만 약 5~6Pass가 소요됨으로써 다급한 진수 일정에 많은 지장을 초래하고 있다. 또한 능률 향상을 목적으로 용착량 증가효과를 얻기 위해 철분말이나 절선와이어를 개선면내에 충진하고 용접을 수행하나 획기적인 용접능률을 기대하기 어렵고 용접사 기량에 따라 용접 결함이 발생될 수 있다. 이에 따라 용접패스 수를 줄이고 결함 발생이 없는 용접기법 개발이 절실히 필요하였다. 이를 위해 매우 간단하고 효율적인 위빙장치를 제작하여 선탑/탑재 아래보기 용접이음에 1~2패스의 SAW 용접법을 개발하여 용접생산성은 물론 용접품질까지 획기적으로 향상시키는 기술 개발을 완료하였다.

• Korean Journal of Remote Sensing
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• v.37 no.2
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• pp.359-365
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• 2021

GEO-KOMPSAT-2A (GK2A) AMI (Advanced Meteorological Imager) Best Detector Select (BDS) map is pre-determined and uploaded before the satellite launch. After the launch, there is some possibility of a detector performance change driven by an abrupt temperature variation and thus the status of BDS map needs to be evaluated and updated if necessary. To investigate performance of entire elements of the detectors, AMI BDS analyses were conducted based on a technical note provided from the AMI vendor (L3HARRIS). The concept of the BDS analysis is to investigate the stability of signals from detectors while they are staring at targets (deep space and internal calibration target). For this purpose, Long Time Series (LTS) and Output Voltage vs. Bias Voltage (V-V) methods are used. The LTS for 30 secs and the V-V for two secs are spanned respectively for looking at the targets to compute noise components of detectors. To get the necessary data sets, these activities were conducted during the In-Orbit Test (IOT) period since a normal operation of AMI is stopped and special mission plans are commanded. With collected data sets during the GK2A IOT, AMI BDS map was intensively examined. It was found that about 1% of entire detector elements, which were evaluated at the ground test, showed characteristic changes and those degraded elements are replaced by alternative best ones. The stripping effects on AMI raw images due to the BDS problem were clearly removed when the new BDS map was applied.

• The Bulletin of The Korean Astronomical Society
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• v.34 no.1
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• pp.110.2-110.2
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• 2009

• Aerospace Engineering and Technology
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• v.13 no.2
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• pp.115-121
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• 2014

GEO-KOMPSAT-2 (GK2) program, which develops two advanced geostationary satellites simultaneously after the successful COMS mission (2010~present), is on going. An improved next generation meteorological payload and space weather sensors will be equipped on the GK2A. The space weather sensor will be the Korea's first geostationary space environment monitoring payload. Main objectives of the project are its applications into space weather forecasting and pre-warning of hazardous space weather by monitoring physical phenomena such as distribution of high energetic particles, Earth's magnetic fields and charging currents on the spacecraft at a geostationary orbit using the three space weather sensors(energetic particle detector, magnetometer and charging monitor). The summary of the GK2A space weather sensor development and its system and interface designs were described in the paper.