• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.11
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• pp.513-520
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• 2018

This research concerns the characteristics of tank barrel inner flow according to the barrel length and the pressure of ammunition when fired. By analyzing the flow characteristics of the bore evacuator according to barrel length and ammunition pressure regarding ammunition design, it is possible to prevent the flareback phenomenon that may occur during ammunition operation. Through bore evacuator flow analysis by barrel length and ammunition pressure, we identified key design factors concerning barrel and ammunition compatibility including speed, accuracy, penetration performance and range. Test results found if barrel length is long and ammunition pressure is low, bore evacuator operation time is slow. Therefore, there is a high probability that propellant gas will enter the battle vehicle. Therefore, the correlation analysis method of bore evacuator flow characteristics based on barrel length and ammunition pressure is considered as a primary method to improve operational performance. When designing new ammunition, the correlation analysis method will be used to determine ammunition weight and select the propellant pressure.

• Journal of the Korean Association of Geographic Information Studies
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• v.23 no.3
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• pp.26-67
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• 2020

Synthetic Aperture Radar(SAR) is able to photograph the earth's surface regardless of weather conditions, day and night. Because of its possibility to search for hydrological factors such as soil moisture and groundwater, and its importance is gradually increasing in the field of water resources. SAR began to be mounted on satellites in the 1970s, and about 15 or more satellites were launched as of 2020, which around 10 satellites will be launched within the next 5 years. Recently, various types of SAR technologies such as enhancement of observation width and resolution, multiple polarization and multiple frequencies, and diversification of observation angles were being developed and utilized. In this paper, a brief history of the SAR system, as well as studies for estimating soil moisture and hydrological components were investigated. Up to now hydrological components that can be estimated using SAR satellites include soil moisture, subsurface groundwater discharge, precipitation, snow cover area, leaf area index(LAI), and normalized difference vegetation index(NDVI) and among them, soil moisture is being studied in 17 countries in South Korea, North America, Europe, and India by using the physical model, the IEM(Integral Equation Model) and the artificial intelligence-based ANN(Artificial Neural Network). RADARSAT-1, ENVISAT, ASAR, and ERS-1/2 were the most widely used satellite, but the operation has ended, and utilization of RADARSAT-2, Sentinel-1, and SMAP, which are currently in operation, is gradually increasing. Since Korea is developing a medium-sized satellite for water resources and water disasters equipped with C-band SAR with the goal of launching in 2025, various hydrological components estimation researches using SAR are expected to be active.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.11
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• pp.975-988
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• 2017

Since 2000, about 750 cubesats have been launched as of August 2017 and development and the launch of cubesat increased exponentially. Since standard of cubesat has been proposed in 1999, cubesats have grown considerably beyond the scope of education and technology verification to commercial use in the area of space exploration and earth observation, and the variety of cubesat mission and type has increased recently. In Korea, some universities and individuals have independently developed cubesats since 2000, and cubesat contests which were organized by KARI and sponsored by Ministry of Science and ICT from 2012 highly contributed to cubesat development in Korea. In addition, domestic institutes such as KARI, KASI started to develop cubesats for space science and exploration mission. Nineteen cubesats have been progressed or completed in development until now. In this paper, we present the technical trend and describe all cubesats in Korea.

• Journal of Astronomy and Space Sciences
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• v.21 no.4
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• pp.391-398
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• 2004

Far-ultraviolet Imaging Spectrograph (FIMS) is the main payload of the Korea's first scientific micro satellite STSAT-1, which was launched at Sep. 27 2003 successfully. Major objective of FIMS is observing hot gas in the Galaxy in FUV bands to diagnose the energy flow models of the interstellar medium. Supernova remnants, molecular clouds, and Aurora emission in the geomagnetic pole regions are specific targets for pointing observation. Although the whole system was calibrated before launch, it is essential to perform on-orbit calibration for data analysis. For spectral calibration, we observed airglow lines in the atmosphere since they provide good spectral references. We identify and compare the observed airglow lines with model calculations, and correct the spectral distortion appeared in the detector system to improve the spectral resolution of the system.

• Journal of the Korean Institute of Intelligent Systems
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• v.25 no.5
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• pp.495-501
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• 2015

Abroad warships are confronted with various menaces. The most critical threat of the warship is an Anti-Ship Missile (ASM). The ASM is able to be launched at a variety of environments and platforms. The ASM can evades conventional naval radar systems and electronic countermeasure techniques for providing a fatal damage to the warship. To cope with the ASM, an active decoy is an effective method to minimize the direct damage to the warship. The active decoy increases survivability of the warship because the ASM can lure pursuit of the active decoy instead of the warship. In this paper, our proposed method verifies an available response time of the active decoy to deal with the ASM using the active decoy of the warship in marine environments. We defined models of the warship, the ASM, and the active decoy, and executed simulation by combining the models. By the simulation result, the proposed method demonstrated the superiority of the mobile active decoy of the response time decoy among various active decoys, and estimated a protection area to prevent the ASM according the response time of the mobile active decoy against the ASM.

• 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.

• Journal of Chest Surgery
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• v.41 no.5
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• pp.675-678
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• 2008

A 42-year-old male was admitted because of an anterior neck injury due to accidental firing of a nail gun. On chest X-ray, the nail was stuck in the anterior neck, migrated to the chest, and then to the abdomen. Only the trachea was damaged, leaving no injury in the esophagus. The nail in the intestine was removed by colonoscopy. The patient showed complete recovery without complications after fasting and conservative treatment. We report this case with a literature review.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.8
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• pp.94-102
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• 2002

Since it would be almost impossible to recover and/or repair the satellite in space once it has been launched, a detailed analysis and design, manufacturing using the high quality workmanship, and qualification and acceptance tests in space-simulation environments are necessary for all satellite components prior to launch. Even though these efforts arc made, the failure can still occur. Therefore, redundancy should be considered in the satellite design for continuous operations in preparation for part or equipment failure. In this paper, the reliability analysis of the transponder, which is a payload of Communications & Broadcasting Satellite being developed by ETRI, was performed and compared for various design cases with different redundancies to find the optimal design. The optimal design has been finalized by investigating how the redundant components are composed from the viewpoint of technical performance measures, such as reliability, cost, schedule, and mass.

• Journal of Astronomy and Space Sciences
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• v.21 no.4
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• pp.383-390
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• 2004

We describe the in-flight sensitivity calibration of the Far ultraviolet Imaging Spectrograph (FIMS, also known as SPEAR) onboard the first Korean science satellite, STSAT-1, which was launched in September 2003. The sensitivity calibration is based on a comparison of the FIMS observations of the hot white dwarf G191B2B, and two O-type stars Alpha-Cam, HD93521 with the HUT (Hopkins Ultraviolet Telescope) observations. The FIMS observations for the calibration targets have been conducted from November 2003 through May 2004. The effective areas calculated from the targets are compared with each other.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.1
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• pp.94.1-94.1
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• 2012

천리안위성은 우리나라 최초의 정지궤도복합위성(COMS: Communication, Ocean, and Meteorological Satellite)으로 2010년 6월 27일, 남미 기아나 쿠루기지에서 아리안-5 로켓에 의해 발사된 후 동경 128.2도, 적도 상공 약 35,800 km 고도의 정지궤도에 안착되었다. 이 후 궤도상시험 기간과 안정화 기간을 거쳐 2011년 4월 1일, 기상청은 위성자료 서비스를 시작하였다. 천리안위성의 기상영상기는 한반도 주변의 기상변화와 전 지구적 기후 변화 및 대기 운동을 감시하기 위해 실시간 관측 및 전송 시스템을 갖춘 탑재체이다. 이 기상영상기는 하루 8번의 지구 반면 영역과 각각 80번 내외의 북반구 및 한반도 영역을 관측하며, 이 자료는 지상에서 복사보정과 기하보정을 거친 후 위성을 통해 다시 사용자에게 배포된다. 천리안위성 기상영상기는 쉼 없이 관측하고, 일정 시간 이내에 그 자료를 배포해야 한다. 이러한 자료서비스는 운영시스템의 장애나 자연현상에 의한 자료 미수신 혹은 미처리가 발생할 경우 운영 결과 및 성과에 영향을 미친다. 이와 같은 장애에 대비해 국가기상위성센터는 이중화된 시스템을 구축했으며, 자료 백업 부기관으로서 한국항공우주연구원과의 사이트 이중화도 시행하고 있다. 그러나 정지궤도에 있는 위성과 태양 및 지구의 역학적인 관계에 따라 태양 전파 잡음의 영향인 태양간섭과, 위성 태양전지판 충전 장애를 일으킬 수 있는 위성식, 그리고 위성 자정 주변에 발생할 수 있는 태양광 침입 및 산란광 영향 등은 미리 예측되어야 하며, 이 시기 운영 방안 마련과 사용자 공지 등의 조치가 수반되어야 한다. 국가기상위성센터는 춘 추분 시기에 발생하는 이러한 태양 영향을 예측하고 검증했으며, 이 시기 위성 및 지상국의 효율적인 운영방안을 마련하였다.