• Title/Summary/Keyword: operational ground

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Optical Design of A Compact Imaging Spectrometer for STSAT3

  • Lee, Jun-Ho;Jang, Tae-Seong;Yang, Ho-Soon;Rhee, Seung-Wu
    • Journal of the Optical Society of Korea
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    • v.12 no.4
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    • pp.262-268
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    • 2008
  • A compact imaging spectrometer (COMIS) for use in the STSAT3 microsatellite is currently under development. It is scheduled to be launched into a low Sun-synchronous Earth orbit (${\sim}700km$) by the end of 2010. COMIS was inspired by the success of CHRIS, which is a small hyperspectral imager developed for the ESA microsatellite PROBA. COMIS is designed to achieve nearly equivalent imaging capabilities of CHRIS in a smaller (65 mm diameter and 4.3 kg mass) and mechanically superior (in terms of alignment and robustness) package. Its main operational goal will be the imaging of Earth's surface and atmosphere with ground sampling distances of ${\sim}30m$ at the $18{\sim}62$ spectral bands ($4.0{\sim}1.05{\mu}m$). This imaging will be used for environmental monitoring, such as the in-land water quality monitoring of Paldang Lake, which is located next to Seoul, South Korea. The optics of COMIS consists of two parts: imaging telescope and dispersing relay optics. The imaging telescope, which operates at an f-ratio of 4.6, forms an image (of Earth's surface or atmosphere) onto an intermediate image plane. The dispersion relay optics disperses the image and relay it onto a CCD plane. All COMIS lenses and mirrors are spherical and are made from used silica exclusively. In addition, the optics is designed such that the optical axis of the dispersed image is parallel to the optical axis of the telescope. Previous efforts focused on manufacturing ease, alignment, assembly, testing, and improved robustness in space environments.

Preliminary Analysis on Characteristics of Attitude Control based on Operation Scenario of Small SAR Satellite Mission, S-STEP (초소형 SAR 위성 S-STEP의 임무 시나리오에 따른 자세 제어 성능 예비 분석)

  • Lee, Eunji;Park, Jinhan;Song, Sung-Chan;Oh, Hyun-Ung
    • Journal of Aerospace System Engineering
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    • v.16 no.5
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    • pp.49-56
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    • 2022
  • S-STEP is a small SAR satellite mission that monitors time-limited emergency targets and military anomalies in areas of interest, achieving the average revisit in less than 30 minutes by deploying a constellation of 32 satellites in low orbit at an altitude of 510 km. The mission operation mode of S-STEP is divided into normal mode, observation mode, communication mode, and orbit maintenance mode. Further,, the attitude control mode is subdivides into initial detumbling, sun pointing, target pointing, ground station pointing, and thrust direction maintenance. Based on the preliminary mission operational scenario and the satellite's characteristics, this study analyzed the attitude control performance during initial detumbling and observation modes. It verifies that each mode's attitude control accuracy requirements within the time allotted by the scenario of the S-STEP achieved.

A Study on the Application of a Fully Electric Propulsion System for Geostationary Missions (정지궤도위성의 완전 전기추진시스템 적용방안 연구)

  • Choi, Jaedong;Park, Bongkyu
    • Journal of Aerospace System Engineering
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    • v.16 no.5
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    • pp.26-34
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    • 2022
  • The propulsion system of geostationary orbiting satellites is typically used to raise the orbit into a transfer orbit, maintain the orbital position in the south/north, east/west direction in regular operation, and accumulate momentum in the south/north and east/west direction. Recently, when an electric propulsion system is used in a geostationary orbit satellite, the payload capacity can be increased by about 40% compared to a chemical propulsion system. However, despite these advantages, using an electric propulsion system has several limitations that should apply to all geostationary orbiting satellites. This paper discusses the operational constraints to consider when developing an indigenous geostationary satellite using a fully electric propulsion, radiation exposure, and control mechanism design due to unit displacement and floating ground-design. A high-voltage control unit for electric drives were analyzed.

A Study on the Development of Advanced LOSA Method (진보된 LOSA 방법론 개발에 관한 연구 )

  • Jihun Choi
    • Journal of Advanced Navigation Technology
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    • v.27 no.4
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    • pp.351-355
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    • 2023
  • The need for Advanced LOSA arises from the limitations and drawbacks of traditional LOSA. Amended LOSA aims to address some of the shortcomings of the original methodology and make it more effective and relevant to current aviation safety needs. Some of the key reasons for developing Advanced LOSA include Enhancing the scope, Improving data collection and analysis, Providing more targeted safety recommendations. First, Traditional LOSA mainly focuses on flight deck operations, but Advanced LOSA expands the scope to include other operational areas such as cabin operations, ground handling, and maintenance. Second, Advanced LOSA can build a Forecasting System that can predict the future through data collection and data analysis. Third, Advanced LOSA aims to provide more specific and targeted safety recommendations based on the Aviation data collection and Aviation data analysis. Overall, Advanced LOSA seeks to improve aviation safety by addressing the limitations of traditional LOSA and providing a more comprehensive and effective methodology for identifying and mitigating safety risks in aviation operations.

A Case Study on FPV Drone Combats of the Ukrainian Forces (우크라이나군의 FPV드론 전투 사례 연구)

  • Kang-Il Seo;Sang-Keun Cho;Sang-Hyuk Park
    • The Journal of the Convergence on Culture Technology
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    • v.9 no.3
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    • pp.263-270
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    • 2023
  • The Ukraine-Russia war is a testing ground for High-Tech weapons and the first full-scale drone warfare. The Ukrainian military has been aggressively deploying a variety of reconnaissance and attack drones on the battlefield, and more recently, FPV drones, also known as racing drones, have been fitted with bombs as a game-changer in small-unit combat. To better understand these FPV drones, this article reviews their definition, aircraft components, and key characteristics, and draws implications from the Ukrainian military's FPV combat experience. In the future, the combination of artificial intelligence and swarming technology will make FPV drones even more lethal. Accordingly, the need to develop FPV drones suitable for the future operational environment on the Korean Peninsula is increasing, and follow-up research is needed to specify fighting methods and optimize related technologies.

Results and Lessons Learned from the Operation of a Cubesat for the Microgravity Science Mission with Shared Ground Stations (공유 지상국을 활용하여 획득한 마이크로중력 과학임무 큐브위성의 운영 결과와 교훈 )

  • Myung-Kyu Lee;Seul-Hyun Park
    • Journal of Space Technology and Applications
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    • v.4 no.2
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    • pp.137-152
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    • 2024
  • Currently, investigations in microgravity environments are carried out in a variety of applications, including drop towers, where experiments can be performed for short periods of time, and space stations, where time is not limited. However, producing a microgravity environment for long-term scientific research requires huge development expenditures and efforts. As a result, if the microgravity experiment is carried out on a cubesat, the variety of scientific studies will likely increase even more due to its low cost. The Korea Microgravity Science Laboratory (KMSL) cubesat, which has these features, is a satellite that has carried out microgravity science missions. On March 22, 2021, the KMSL satellite was launched by a Soyuz2.1a from Baikonur in Kazakhstan and operated normally for nearly two months. This article presents results and lessons gained for successfully completing science missions in microgravity based on the KMSL satellite's operational experience.

A Study on the Operational Planning Assist System for Ground Forces (지상군 작전계획 수립 보조 시스템 설계 연구)

  • Ikhyun Kim;Sunju Lee
    • Journal of The Korean Institute of Defense Technology
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    • v.5 no.1
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    • pp.7-18
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    • 2023
  • The military leader makes an operation plan to accomplish combat missions. The current doctrine for an operation planning requires the use of simple and clear procedures and methods that can be carried out with human effort under adverse conditions in the field. The work in the process of an operation planning can be said to be a series of decision-making, and the criteria for decision-making generally apply mission variables. However, detailed standards are not fixed as doctrine, but are creatively established and applied. However, for AI-based decision-making, it is necessary to formalize the criteria and the format used. This paper first aims to standardize various criteria and forms to present a method that can be used in a semi-automated assist system, and to seek a plan to artificialize it. To this end, mathematical models and decision-making methods established in the field of operations research were applied to improve efficiency.

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A re-appraisal of scoring items in state assessment of NATM tunnel considering influencing factors causing longitudinal cracks (종방향균열 영향인자 분석을 통한 NATM터널 정밀안전진단 상태평가 항목의 재검토)

  • Choo, Jin-Ho;Yoo, Chang-Kyoon;Oh, Young-Chul;Lee, In-Mo
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.21 no.4
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    • pp.479-499
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    • 2019
  • State assessment of an operational tunnel is usually done by performing visual inspection and durability tests by following the detailed guideline for safety inspection (SI) and/ or precision inspection for safety and diagnosis (PISD). In this study, 12 NATM tunnels, which have been operational for more than 10 years, were inspected to figure out the cause of longitudinal cracks for the purpose of modifying the scoring items in the state assessment NATM tunnel related to the longitudinal crack and the thickness of concrete lining. All investigated tunnels were classified into four groups depending on the shape and usage of each tunnel. The causes of longitudinal crack occurrence were analyzed by investigating the correlations between the longitudinal crack and the following four factors: the patterns of ground excavation; construction state of primary support system; characteristics of material properties of the concrete lining; and thickness of lining which was obtained by Ground Penetration Radar (GPR) tests. It was found that influencing factors causing longitudinal cracks in the lining were closely related with the construction condition of the primary support system, i.e. shotcrete, rockbolt, and steel-rib; crack occurrences were not much affected by the excavation patterns. As for the properties of concrete lining materials, occurrence of the longitudinal crack was mostly affected by the following three items: w/c ratio; contents of cement; and strength of lining. When estimating the lining thickness of the concrete lining by GPR tests and taking thickness effect into account in the statement assessment, it was concluded that increase of the index score by an average of 0.03 (ranging from 0.01 up to 0.071) is needed; a more realistic way of state assessment should be proposed in which the increased index score caused by lack of lining thickness should be taken into account.

Preservation of Fish Community by the Construction of the Tamjin Dam (탐진댐 건설에 따른 어류군집 보전방안)

  • Choi, Chung-Gil;Joh, Seong-Ju;Kim, Jong-Hae;Kim, Dong-Sup
    • Korean Journal of Ecology and Environment
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    • v.35 no.3 s.99
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    • pp.237-246
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    • 2002
  • Tamjin Dam is built in the upper reaches of the Tamjin River which flows through the Janghung-gun and Gangjin-gun of the Jeollanamdo, Korea. In order to map out a preservation strategy of the fish community from dam construction, We studied the distribution of fish distribution and changes of the habitat environment. we found 49 fish species inhabiting in the downstream and upstream of the Tamjin Dam. Among them, migratory fish were two species sweet smelt, Plecoglossus altivelis and freshwater eel, Anguilla japonica. The Coreoperca kawamebari which designated as a species to be protected by The Ministry of Environment of Korea was also observed. After the dam construction, reservoir would be filled with water and running water system will change to standing water system. Then the habitat and spawning space for mountain torrent fish will be reduced and the migration of migratory fish to upstream will be blocked. Through our study, we proposed several ways to protect fish community. In order to preserve the reduced habitat and spawning area of mountain torrent fish, a fishway has been diagnosed to be built in the shallow reservoir in the entrance of the upriver. The establishment of artificial spawning ground on the riverside has been recommended. In addition, We propose a creation of a shelter for fresh water eel, Anguilla japonica in areas where the depth of the water is about l0m by laying rocks. Since it is difficult for a spawning ground to be formed naturally in the reservoir due to the year-round changes in water level, We suggested a floating spawning facility using an artificial fixture. In the downstream of the dam, a waterway-style habitat and spawning ground in the river and increasing the diversity and abundance of fish fauna in the Tamjin River. A low-cost and highly efficient operational fishway has been recommended so that migratory fish such as Plecoglossus altivelis (sweetfish) can migrate from the lower reaches to the upper reaches of the river.

PRC Maritime Operational Capability and the Task for the ROK Military (중국군의 해양작전능력과 한국군의 과제)

  • Kim, Min-Seok
    • Strategy21
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    • s.33
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    • pp.65-112
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    • 2014
  • Recent trends show that the PRC has stepped aside its "army-centered approach" and placed greater emphasis on its Navy and Air Force for a wider range of operations, thereby reducing its ground force and harnessing its economic power and military technology into naval development. A quantitative growth of the PLA Navy itself is no surprise as this is not a recent phenomenon. Now is the time to pay closer attention to the level of PRC naval force's performance and the extent of its warfighting capacity in the maritime domain. It is also worth asking what China can do with its widening naval power foundation. In short, it is time to delve into several possible scenarios I which the PRC poses a real threat. With this in mind, in Section Two the paper seeks to observe the construction progress of PRC's naval power and its future prospects up to the year 2020, and categorize time frame according to its major force improvement trends. By analyzing qualitative improvements made over time, such as the scale of investment and the number of ships compared to increase in displacement (tonnage), this paper attempts to identify salient features in the construction of naval power. Chapter Three sets out performance evaluation on each type of PRC naval ships as well as capabilities of the Navy, Air Force, the Second Artillery (i.e., strategic missile forces) and satellites that could support maritime warfare. Finall, the concluding chapter estimates the PRC's maritime warfighting capability as anticipated in respective conflict scenarios, and considers its impact on the Korean Peninsula and proposes the directions ROK should steer in response. First of all, since the 1980s the PRC navy has undergone transitions as the focus of its military strategic outlook shifted from ground warfare to maritime warfare, and within 30 years of its effort to construct naval power while greatly reducing the size of its ground forces, the PRC has succeeded in building its naval power next to the U.S.'s in the world in terms of number, with acquisition of an aircraft carrier, Chinese-version of the Aegis, submarines and so on. The PRC also enjoys great potentials to qualitatively develop its forces such as indigenous aircraft carriers, next-generation strategic submarines, next-generation destroyers and so forth, which is possible because the PRC has accumulated its independent production capabilities in the process of its 30-year-long efforts. Secondly, one could argue that ROK still has its chances of coping with the PRC in naval power since, despite its continuous efforts, many estimate that the PRC naval force is roughly ten or more years behind that of superpowers such as the U.S., on areas including radar detection capability, EW capability, C4I and data-link systems, doctrines on force employment as well as tactics, and such gap cannot be easily overcome. The most probable scenarios involving the PRC in sea areas surrounding the Korean Peninsula are: first, upon the outbreak of war in the peninsula, the PRC may pursue military intervention through sea, thereby undermining efforts of the ROK-U.S. combined operations; second, ROK-PRC or PRC-Japan conflicts over maritime jurisdiction or ownership over the Senkaku/Diaoyu islands could inflict damage to ROK territorial sovereignty or economic gains. The PRC would likely attempt to resolve the conflict employing blitzkrieg tactics before U.S. forces arrive on the scene, while at the same time delaying and denying access of the incoming U.S. forces. If this proves unattainable, the PRC could take a course of action adopting "long-term attrition warfare," thus weakening its enemy's sustainability. All in all, thiss paper makes three proposals on how the ROK should respond. First, modern warfare as well as the emergent future warfare demonstrates that the center stage of battle is no longer the domestic territory, but rather further away into the sea and space. In this respect, the ROKN should take advantage of the distinct feature of battle space on the peninsula, which is surrounded by the seas, and obtain capabilities to intercept more than 50 percent of the enemy's ballistic missiles, including those of North Korea. In tandem with this capacity, employment of a large scale of UAV/F Carrier for Kill Chain operations should enhance effectiveness. This is because conditions are more favorable to defend from sea, on matters concerning accuracy rates against enemy targets, minimized threat of friendly damage, and cost effectiveness. Second, to maintain readiness for a North Korean crisis where timely deployment of US forces is not possible, the ROKN ought to obtain capabilities to hold the enemy attack at bay while deterring PRC naval intervention. It is also argued that ROKN should strengthen its power so as to protect national interests in the seas surrounding the peninsula without support from the USN, should ROK-PRC or ROK-Japan conflict arise concerning maritime jurisprudence. Third, the ROK should fortify infrastructures for independent construction of naval power and expand its R&D efforts, and for this purpose, the ROK should make the most of the advantages stemming from the ROK-U.S. alliance inducing active support from the United States. The rationale behind this argument is that while it is strategically effective to rely on alliance or jump on the bandwagon, the ultimate goal is always to acquire an independent response capability as much as possible.