• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.5
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• pp.391-399
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• 2020

KASI (Korea Astronomy and Space Science Institute) has been developing the multipurpose laser tracking system with three functions of satellite laser tracking, adaptive optics and space debris laser tracking for scientific research and national space missions. The space debris laser tracking system provides the distance to space debris without a laser retro-reflector array by using a high power pulse laser, which employs a spinning disk to change the optical path between the transmit and receive beams. The spinning disk causes the collision band which is unable to reflect the returned signal to a detector and then has an effect on the tracking coverage of space debris. This study proposed the mathematical model for tracking coverage by taking into account the various specifications of spinning disk such as disk size, spinning velocity and collision rate between the disk and hole. In addition, the spinning disk specifications were analyzed in terms of tracking coverage and collision band based on the mathematical model to investigate tracking requirements of the Geochang laser tracking system.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.9
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• pp.746-756
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• 2017

An algorithm is developed to generate measurement data of deep space network for Korea Pathfinder Lunar Orbiter (KPLO) mission. The algorithm can provide corrected measurement data for the Orbit Determination (OD) module in deep space. This study describes how to generate the computed data such as range, Doppler, azimuth angle and elevation angle. The geometric data were obtained by General Mission Analysis Tool (GMAT) simulation and the corrected data were calculated with measurement models. Therefore, the result of total delay includes effects of tropospheric delay, ionospheric delay, charged particle delay, antenna offset delay, and tropospheric refraction delay. The computed measurement data were validated by comparison with the results from Orbit Determination ToolBoX (ODTBX).

• Current Industrial and Technological Trends in Aerospace
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• v.8 no.2
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• pp.31-38
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• 2010

Environment and climate changes affect all aspects of our society. The enhanced remote sensing technology made the satellite to be widely used in the environment monitoring applications. Geostationary environmental monitoring is also actively researched due to the increased needs for the monitoring of diurnal environmental changes, troposhperic pollution and its origin. In this paper, recent development trends of geostationary environment monitoring payloads are introduced. GEO-CAFE and GIFTS missions are researched by the leading of the NASA and Sentinel-4 by the ESA. Those missions are in the state of detailed conceptual design and hardware development preparing with the launch plan in the late 2010s. By considering these development trends, domestic environment monitoring payloads shall be developed with careful analysis on the mission and data application.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.2
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• pp.158-164
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• 2014

LEO(Low Earth Orbit) Satellite which is discarded should be reentered to atmosphere in 25 years by '25 years rule' of IADC(Inter-Agency Space Debris Coordination Committee) Guidelines. If the parts of satellite are survived from severe aerothermodynamic condition, it could damage to human and property. South Korea operates KOMPSAT-2 and STSAT series as LEO satellite. It is necessary to dispose of them by reentering atmosphere. Therefore this paper analyze the trajectory, survivability, casualty area and casualty probability of a virtual LEO satellite using ESA(European Space Agency)'s DRAMA(Debris Risk Assesment and Mitigation Analysis) tool. As a result, it is noted that casuality area is $15.2742m^2$ and casualty probability is 5.9614E-03 then will be survived 198.831kg.

• Journal of Aerospace System Engineering
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• v.17 no.6
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• pp.108-117
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• 2023

Thus far, a mission software component of the KT-1 military fixed-wing aircraft for overseas export has been developed through international joint development with foreign companies. The reliability of the software component could be certified by complying with the development environment and procedures of foreign companies based on DO-178B. However, recently, DO-178C certification is required for overseas exports, and reliability tests to comply with the weapon system software development guidelines are required for domestic military forces. In this paper, we describe the problems in obtaining domestic airworthiness certification in the international joint development of a previously developed KT-1 export-typed aircraft system integration project. To this end, we find a solution to comply with both DO-178C and the Weapon System Software Development and Management Manual and provide the optimal software reliability test method.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.11
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• pp.997-1005
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• 2016

Flight software plays an important role in operating satellites, such as processing commands from ground station, controlling satellites and processing mission data. Reliability is the most important thing in flight software and many verifications and tests are needed for assuring it. this causes an increase of cost and period of development. So NASA has developed a reusable flight software platform to apply to their satellite projects. The CFS(Core Flight System) is the very result. We are developing our flight software for a nano-satellite based on NASA CFS. We have tested core services and functions provided in CFS and we have designed and implemented flight software based on these.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.9
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• pp.711-723
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• 2017

This paper proposes a flight control system for an organic flight array(OFA) which has a new configuration to consist of multi modularized ducted-fan unmanned aerial vehicles (UAVs). The OFA is able to apply to various missions such as indoor reconnaissance, communication relay, and radar jamming by using capability of hover flight. The OFA has a distinguished advantage due to reconfigurable structure to assemble or separate with respect to its missions or operational conditions. A dynamic modelling of the OFA is derived based on equations of motion of the single ducted-fan modules. In order to apply nonlinear control method, an affine system of attitude dynamics is derived. Moreover, the control system is composed of a back-stepping controller for attitude control and a PID controller for position control. Then the performance of the proposed controller is verified via a numerical simulation under wind disturbance.

• The Journal of the Petrological Society of Korea
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• v.19 no.4
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• pp.245-254
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• 2010

Technology of surface investigation using X-ray is one of widely used technology nowadays. This technique has been numerously used for planetary surface investigations for both orbital and rover scientific instruments. Korea has a plan to send an orbiter and lander to the Moon by the early 2020s. Therefore, the time has come for Korean researchers to develop major scientific instruments and start to do research on basic research for the Moon. Because of this situation, we firstly investigate X-ray technology, which is essential as one of core techniques of planetary remote sensing from the orbit and ground. This paper presents the current status of planetary exploration using X-ray techniques and new development of worldwide X-ray technology which could be adapted for prospective planetary missions.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.531-535
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• 2015

본 연구에서는 한반도 관측 공백지역인 북한지역에 대하여 레이더와 위성 원격탐사자료를 활용하여 강수량과 토양수분 등 수문기상정보를 생산 및 검증하고 효율적인 수문 모니터링 및 수문 기상 재해 감시와 평가 방안을 수립하고자 한다. 또한, 북한지역의 수문 기상 정보 수집 및 통합 DB를 마련하고 북한 수문기상 포털시스템을 구축함으로써 부처 간 자료를 공유할 수 있는 매개체를 마련하여 일관된 정책 수립과 효율적인 물관리를 도모하고자 한다. WPMM(Window Probability Matching Method)방법을 기반으로 구성된 RAD-RAR(Rain rate system) 산정 알고리즘(Rosenfeld et al., 1993)을 활용하여 산출된 합성 강우장 데이터의 정확성을 비교 분석하기 위해 접경지역 AWS 강수량과 세계기상통신망(GTS)기반 강수량을 산출하여 각각 레이더 강수량과 검증분석을 실시하였다. 연구기간은 2012년과 2013년 여름철 기간 중 5개의 기간을 선별하였다. 연구 기간 동안의 RAR 합성 강우장 데이터를 이용하여, 기간 중 1시간 동안 누적된 강수량을 산출하고 접경지역 AWS 강수량과 비교하였고 12시간 누적 강수량을 산출하여 GTS 강수량과 비교 분석을 실시하였다. 전반적으로 레이더 강수량에 비해 AWS 강수량이 더 높게 나타났으며 마찬가지로 레이더 강수량과 GTS 강수량의 비를 통해 레이더 자료가 상대적으로 과소추정되고 있음을 확인 할 수 있었다. 미항공우주국(NASA)과 일본항공우주국(JAXA)을 중심으로 진행된 GPM(Global Precipitation Measurement)미션은 한 개의 핵심위성과 마이크로파 복사계를 탑재한 10여개의 보조위성으로 구성되어 있으며, 매 3시간 간격의 전구 강수량 자료 생산에 목적이 있다. 이는 홈페이지를 통해 Level 1, 2, 3의 GPM 데이터를 배포하고 있다. 특히 Level 2 데이터는 언급된 3시간 간격의 전구 강수량 데이터를 제공한다. 이 경우 복사량을 강수량으로 변환하는 번거로움을 덜 수 있으며 NASA가 제공하는 Panoply라는 프로그램을 이용하여 한반도 강수 자료 가시화가 가능하다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.6
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• pp.481-488
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• 2021

The satellite telecommand processing system is the only way to provide telecommands for status monitoring, control, and mission execution. Domestic satellites can be divided into science, technology, and multi-purpose satellites, and geostationary satellites. These Satellites uses CCSDS standard protocol to communicate with ground stations. However, existing domestic satellites use only software to decode telecommands which increases cost of software development and verification of the developed software. Performance of software only approach is relatively low compared to hardware. In this paper, we present ASIC processing system specifically designed to decode telecommands. The system consists of a telecommand RAM, a protocol RAM/ROM, an ASIC, an interface unit of FPGA, and a relay block. The system handles general commands and pulse commands that are used in satellites. We established a ground station equipment and test environment to verify the system functionality, The result shows that our system reduces the development cost by 1/5 and improves the performance by 10⁵ times compared to the previous systems that decode telecommands only by software.