• Journal of Astronomy and Space Sciences
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• v.24 no.4
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• pp.297-308
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• 2007

The AOPOD (Atmosphere Occultation and Precision Orbit Determination) system, the secondary payload of KOMPSAT (KOrea Multi-Purpose SATellite)-5 scheduled to be launched in 2010, shall provide GPS radio occultation data. In this paper, we simulated the GPS radio occultation characteristic of KOMPSAT-5 and retrieved electron density profiles using KROPS (KASI Radio Occultation Processing Software). The electron density retrieved from CHAMP (CHAllenging Minisatellite Payload) GPS radio occultation data on June 20, 2004 was compared with IRI (International Reference Ionosphere) - 2001, PLP (Planar Langmuir Probe), and ionosonde measurements. When the result was compared with ionosonde measurements, the discrepancies were 5 km on the $F_2$ peak height ($hmF_2$) and $3{\times}10^{10}el/m^3$ on the electron density of the $F_2$ peak height ($NmF_2$). By comparing with the Laugmuir Probe measurements of CHAMP satellite (PLP), both agrees with $1.6{\times}10^{11}el/m^3$ at the height of 365.6 km.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.8A
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• pp.1149-1155
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• 1999

LEO(Low altitude Earth Orbit) Satellite systems have been utilized in the field of earth and scientific observation (cartography mission, ocean color monitoring, bioglogical coeanography, space environments observation by space physics sensor, and meteorological observation, atmospheric observation etc.), and the field of military (military communications and secret information, enemy reconnaissance etc.), and recently been developing in the field of mobile satellite commnication of GMPCS for commercial utilization. In Korea, KOMPSAT I satellite and ground system are been developing and planed to be lunched on October 1999 In this paper, the link budge of the TT&C system for LEO satellite is described and the relations between elevation angle and pass time of LEO satellite are calculated according to satellite moving. And the packet error rates of receiving data are derived three packet error rates(PER) of real-time(RT) mode, playback(PB) mode, and real-time and range tone(RT+RNG) mode are estimated according to pass time of satellite. The results of PER are the best at real-time and the worst at real-time mode and range mode at the all pass time of satellite. The average error free packet(EFP)s of real-time mode, playback mode, and real-time and range tone for the pass time of satellite are obtained as 99.999999%, 99.999912%, 99.995945% respectively. Therefore, transmission sequence of telemetry data are determined such as PER sequence according to pass time, namely, real-time, playback, and real-time and range mode.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.8
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• pp.671-680
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• 2021

This paper deals with the contents of designing and producing reconnaissance hardware and software, and verifying the functions after being installed on the CanSat platform and ground stations. The main reconnaissance mission is largely composed of two things: terrain search that renders the surrounding terrain in 3D using radar, GPS, and IMU sensors, and real-time detection of major objects through optical camera image analysis. In addition, data analysis efficiency was improved through GUI software to enhance the completeness of the CanSat system. Specifically, software that can check terrain information and object detection information in real time at the ground station was produced, and mission failure was prevented through abnormal packet exception processing and system initialization functions. Communication through LTE and AWS server was used as the main channel, and ZigBee was used as the auxiliary channel. The completed CanSat was tested for air fall using a rocket launch method and a drone mount method. In experimental results, the terrain search and object detection performance was excellent, and all the results were processed in real-time and then successfully displayed on the ground station software.

• Korean Journal of Remote Sensing
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• v.36 no.5_2
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• pp.893-906
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• 2020

This paper reports on the analysis of the location accuracy of a precision image generation system manufactured for CAS 500. The planned launch date of the CAS 500 is 2021, and since it has not yet been launched, the analysis was performed using KOMPSAT-3A satellite images having similar specifications to the CAS 500. In this paper, we have checked the geolocation accuracy of initial sensor model, the model point geolocation accuracy of the precise sensor model, the geolocation accuracy of the precise sensor model using the check point, and the geolocation accuracy of the precise orthoimage using 30 images of the Korean Peninsula. In this study, the target geolocation accuracy is to have an RMSE within 2 pixels when an accurate ground control point is secured. As a result, it was confirmed that the geolocation accuracy of the precision sensor model using the checkpoint was about 1.85 pixels in South Korea and about 2.04 pixels in North Korea, and the geolocation accuracy of the precise orthoimage was about 1.15 m in South Korea and about 3.23 m in North Korea. Overall, it was confirmed that the accuracy of North Korea was low compared to that of South Korea, and this was confirmed to have affected the measured accuracy because the GCP (Ground Control Point) quality of the North Korea images was poor compared to that of South Korea. In addition, it was confirmed that the accuracy of the precision orthoimage was slightly lower than that of precision sensor medel, especially in North Korea. It was judged that this occurred from the error of the DTM (Digital Terrain Model) used for orthogonal correction. In addition to the causes suggested by this paper, additional studies should be conducted on factors that may affect the position accuracy.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2002.04a
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• pp.3-10
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• 2002

요즘 측량분야에서 Geomatics 또는 Geoinformatics라는 새로운 용어가 대두되고 있다. 해외의 유수 기관 및 대학교에서도 측량이라는 학과명 또는 기관명을 Geomatics라는 용어로 교체하고 있으며, 이는 측량분야의 다양화와 학제간 연구수행의 필요성을 반영하는 것이다. 최근 45로 일컬어지는 GPS, 원격탐사(RS), GIS, ITS의 경우 각기 독자적인 영역을 구축하기보다는 상호 보완적인 역할을 하며 통합되어 가는 추세이다. 1950년대에 기본적인 위성관측기술 및 계산 기술의 개발을 시작으로 1980년대에 이르러서는 위성 기술은 측지학 및 측량 분야에 적용되기 시작했다. 그 대표적인 것이 GPS(Global Positioning System)로 기존의 천체측정학 방식을 대체하는 유용한 위치결정 수단으로 사용되기 시작했다. DNSS로부터 시작된 GPS는 측지 측량분야, 지구물리학분야, 항법 및 교통, GIS Mapping, 기상 및 해양, 재난 및 레저, 인공위성 궤도결정 등 다양한 분야에 적용되었으며, 특히 2000년 5월 1일 SA가 해제되면서 그 활용도는 더욱 증가하고 있다. 위성원격탐사의 경우 초창기에 중ㆍ저해상도의 다중분광영상에서 시작하여 그 해상도가 꾸준히 향상되어 오늘날 0.61 미터급 고해상도 위성인 QuickBird 위성이 발사되어 운용 중에 있다. 위성영상의 공간해상도, 분광해상도, 방사해상도는 향후 계속 향상될 것이며 이에 따른 방대한 데이터의 처리 문제 및 하드웨어/소프트웨어 지원에 대한 연구가 수반되어야 할 것이다. GPS 및 원격탐사(RS)는 더 이상 독자적인 영역으로서가 아니라 Geomatics를 이루는 중요한 분야로서 타 시스템과의 보완적인 관계로서 통합되어 나갈 것이다. 이를 위해서는 공간정보에 대한 표준화 및 데이터 처리, 통합, 시스템 구축을 위한 기술적 연구가 계속 진행되어야 할 것이다.분 공부상면적보다 늘어났다. 2. 좌표의 이동량이 일률적이지 못하므로 기초점에 대한 문제라고 생각되며, 따라서 도해지적을 수치지적으로 전환함에 있어서 가장 우선되어야 할 사항이 기초점 정비라 하겠다.승이 뚜렷하였다. 따라서 비파 착즙액 첨가 기능성 yoghurt 제조시 비파 착즙액을 10% 첨가하여 혼합 starter로 Str. thermophilus와 Lac. acidophilus 혼합균주를 사용하는 것이 이들 유산균의 증식에 가장 적합한 것으로 나타났다.타났다..297, 0.293, 0.205에서 50일 경과 후 0.612, 0.472, 0.898로 비살균에서 높은 값을 보였다. 따라서 비살균의 경우 저장말기에 TBA값이 높아지는 경향을 보였다. 5. L값은 살균처리의 경우 저장 30일 이후 약간 어두워지는 경향을 보였고, 121$^{\circ}C$ 살균처리에서 높은 값을 보였다. 대체로 저장온도가 높고 저장기간이 길어질수록 약간 밝아지는 경향을 보였다. 적색도는 인삼 첨가구의 경우 상온 및 냉장저장에서 10$0^{\circ}C$ 살균이 121$^{\circ}C$ 처리구 보다 약간 높은 값을 보였다. 저장기간에 따른 적색도의 변화는 인삼과 송이 첨가구에서 비교적 안정적이었다. 황색도는 상온 및 냉장저장에서 저장기간에 따라 약간 감소하는 경향을 보인 후 상온저장 50일 째, 냉장 60일 째 가장 높게 나타났다. 121$^{\circ}C$ 살균처리구가 10$0^{\circ}C$ 처리구보다 약간 높은 경향을 보였다.^{\circ}C$$,에서는 20시간 가열시 0.706$\mu\textrm{g}$/kg으로 가장 높게 생성된 후 서서히 감소하였다. 그러나 산값과 공액이중산값은 계속 증가하는 양상을 나타냈다. 즉 B(a)

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.4
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• pp.137-143
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• 2013

The high resolution satellite images are used in many fields such as weather observation, remote sensing, military facilities monitoring, cultural properties protection etc. Although satellite images are obtained in same satellite imaging system, the satellite images are degraded depending on the condition of hardware(optical device, satellite operation altitude, image sensor, etc.). Due to the fact that changing the hardware of satellite imaging system is impossible for resolution enhancement of these degraded satellite after launching a satellite, therefore the method of resolution enhancement with satellite images is necessary. In this paper the resolution is enhances by using a Super Resolution(SR) algorithm. The SR algorithm is an algorithm to enhance the resolution of an image by uniting many low resolution images, so an output image has higher resolution than using other interpolation methods. But It is difficult to obtain many images of the same area. Therefore, to solve this problem, we applied SR after by applying the affine and projection transform. As a results, we found that the images applied SR after affine and projection transform have higher resolution than the images only applied SR.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.7
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• pp.4828-4834
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• 2015

From the moment that a firing pin triggers the detonator to the moment that a grenade leaves a barrel is called Action Time. Since a loading and percussion of 40mm grenade happens simultaneously, action time should be within a certain time in order to prevent a Jamming malfunction. Previously, unreliable action time device of 40mm grenade made it difficult to improve quality assurance of K4 Grenade Machine Gun. Here, various sensors were compared and a special device was designed to seek an accurate measurement on action time. In this device, the gap between a signal from an optical sensor in Firing Pin and that from Eddy current probe in the barrel was recorded and data were sent to a computer in real time. Confirming if action time is within the criteria, it is expected that action time plays an important role in quality assurance on 40mm grenade.

• Journal of Satellite, Information and Communications
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• v.2 no.2
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• pp.41-47
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• 2007

The first geostationary satellite made by Korea, COMS, has the three different payload ; Meteorological sensor, Oceanographic sensor and Ka-band communication payload. There are Meteorological & Ocean Data Communication Subsystem(MODCS) and Telemetry, Command and Ranging Subsystem(TC&R) as other RF radiation sources. MODCS transmits and receives Meteo and Ocean measurement data from/to earth using L-band and TC&R using S-band. The Ka-band communication payload will provide high-speed multimedia services and communication services for natural disaster such as prediction, prevention, and recovery services in the government communications network.Ka-band beacon is for the earth antenna pointing and the experiment of rain fading. This paper gives the analysis results about the mutual radiation effect on Ka-band communication payload, Ka-band beacon, MODCS and TC&R. Up/Down link power and coupling factor including the geometrical position and distance of antenna, filter rejection and degradation factor due to the different polarization are considered. The results show MODCS and TC&R are compatible for Ka-band communication payload and Ka-band beacon does not interfere with MODCS and TC&R normal operation.

• Journal of Astronomy and Space Sciences
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• v.20 no.4
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• pp.339-350
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• 2003

Engineering qualification model payload for a communications and broadcasting satellite(CBS) was developed by ETRI from May, 2000 to April, 2003. For. the purpose of functional test and verification of the payload, a real-time hardware-in-the-loop(HITL) CBS simulator(CBSSIM) was also developed. We assumed that the spacecraft platform for the CBSSIM is a geostationary communication satellite using momentum bias three-axis stabilization control technique based on Koreasat. The payload hardware is combined with CBSSIM via Power, Command and Telemetry System(PCTS) of Electrical Ground Support Equipment(EGSE). CBSSIM is connected with PCTS by TCP/IP and the payload is combined with PCTS by MIL-STD-1553B protocol and DC harness. This simulator runs under the PC-based simulation environment with Windows 2000 operating system. The satellite commands from the operators are transferred to the payload or bus subsystem models through the real-time process block in the simulator. Design requirements of the CBSSIM are to operate in real-time and generate telemetry. CBSSIM provides various graphic monitoring interfaces and control functions and supports both pre-launch and after-launch of a communication satellite system. In this paper, the HITL simulator system including CBSSIM, communications payload and PCTS as the medium of interface between CBSSIM and communications payload will be described in aspects of the system architecture, spacecraft models, and simulator operation environment.

• Journal of Navigation and Port Research
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• v.34 no.8
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• pp.603-607
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• 2010

The LORAN system had been used widely and it was an essential navigation aid for ships in the ocean until the GPS is adopted actively. In particular, it was essential functionality for the ships to sail the oceans. According to the advancement of industry, however, the current accuracy of traditional Loran is insufficient for the utilization of harbour approach, land navigation, and the field of survey and timing. Therefore it is necessary that the study on the improvement of the positioning accuracy of Loran. The one of the improving methods is to measure and compensate the propagation time delay between the transmitter and user's receiver, which is called as additional secondary factor (ASF). In this study, we measured the ASF between the Pohang master transmitting station (9930M) and four points where locate within 33 km apart from the transmitting station, using the measuring technique of the absolute time delay without a time of coincidence (TOC) table. As the result of measurement, the ranging error caused by the propagation delay was about 210 m at 33 km, however it can be reduced up to 40 m with ASF compensation.