• 한국항공운항학회지
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• 제27권4호
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• pp.65-72
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• 2019

There is concern about the increased risk of accidents from manual investments due to ground handling service operators, aging equipment and manpower shortages. Therefore, it is necessary to improve the quality of ground treatment services and safety management at the airport. Therefore, this study analyzed the domestic and overseas ground operation status and the license handling procedure of aircraft handling business. In addition, a case study on the evaluation system of international organizations examined the applicability of the certification body to the Korean situation. It is practical in that it provides policy implications for improving the quality of groundwork not covered in previous studies. This is expected to improve the constitution, improve quality, improve airport operations, and operate safely.

• International Journal of Aeronautical and Space Sciences
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• 제16권3호
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• pp.445-450
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• 2015

Generally, Low Earth Orbit (LEO) satellites are used to collect image or video from earth's surface. The collected data are stored on-board and/or transmitted to the main ground station directly or via polar ground station using terrestrial line. Today, an intersatellite link between a LEO and a GEO satellite allows transmission of the collected data to the main ground station through the GEO satellite. In this study, an approach for a continuous communication starting from LEO through GEO to ground station is proposed by determining the optimum ground station locations. In doing so, diverse ground stations help to determine the GEO orbit as well. Cross-correlation of the long term daily rainfall averages are multiplied with the logarithmic correlation of the sites to calculate the joint correlation of the diverse ground station locations. The minimum values of this joint correlation yield the optimum locations of the ground stations for Q/V-band communication and satellite control operations. Results for several case studies are listed.

• 항공우주산업기술동향
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• 제6권1호
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• pp.56-64
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• 2008

위성체 총조립 및 시험(AIT; Assembly, Integration & Test)을 위한 전기지상지원장비(EGSE ; Electrical Ground Support Equipment)와 위성 임무 준비 및 운용을 위한 관제시스템(MCS; Mission Control System)은 동일한 시스템은 아니지만 많은 공통점과 호환 가능성을 갖고 있다. 하지만 우주 사업의 핵심 지상시스템인EGSE와 MCS는 사용 시기와 개발 조직이 달라서 오랫동안 별도로 개발 및 발전되어 왔다. 그러나 두 시스템이 기술적인 측면에서 유사한 기능과 역할을 하기 때문에 통합 또는 공통 개발에 대한 요구가 끊임없이 제기되고 있으며, 이미 세계적으로ECSS E70과 같은 관련 표준화 작업과 이를 바탕으로 실제 구현된 핵심 지상운영시스템의 개발이 최근에 기술적인 성숙을 이루고 있어 현재 거의 모든 우주 사업에서 핵심 지상운영시스템을 활용하거나 더 나아가 상용 제품을 적용하여 공통지상시스템을 개발하고 있다. EGSE와 MCS의 공통 기능에 관련된 표준화 작업은 ECSS를 통해 국제 표준(ISO, CCSDS 등)을 바탕으로 한 위성의 지상시스템에 대한 유럽 표준화 작업이 ECSS-E-70 Working Group에서 진행되고 있다. 여기서는 우주 산업에 관련된 표준화 단체인 ECSS에 대한 역사, 정책, 조직 및 문서 구조를 포함하여 ECSS에서 현재 진행되고 있는 지상시스템 및 운용 분야 관련 ECSS E70 표준화 작업의 내용 및 현황에 대해서 살펴보고자 한다.

• Journal of Astronomy and Space Sciences
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• 제38권1호
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• pp.65-82
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• 2021

For the vast majority of geostationary satellites currently in orbit, station keeping activities including orbit determination and maneuver planning and execution are ground-directed and dependent on the availability of ground-based satellite control personnel and facilities. However, a requirement linked to satellite autonomy and survivability in cases of interrupted ground support is often one of the stipulated provisions on the satellite platform design. It is especially important for a geostationary military-purposed satellite to remain within its designated orbital window, in order to provide reliable uninterrupted telecommunications services, in the absence of ground-based resources due to warfare or other disasters. In this paper we investigate factors affecting the robustness of a geostationary satellite's orbit in terms of the maximum duration the satellite's station keeping window can be maintained without ground intervention. By comparing simulations of orbit evolution, given different initial conditions and operations strategies, a variation of parameters study has been performed and we have analyzed which factors the duration is most sensitive to. This also provides valuable insights into which factors may be worth controlling by a military or civilian geostationary satellite operator. Our simulations show that the most beneficial factor for maximizing the time a satellite will remain in the station keeping window is the operational practice of pre-emptively loading East-West station keeping maneuvers for automatic execution on board the satellite should ground control capability be lost. The second most beneficial factor is using short station keeping maneuver cycle durations.

• 한국국방경영분석학회지
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• 제7권1호
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• pp.81-117
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• 1981

Mathematical models for hit probabilities of small arms are developed in order to estimate the expected hits on an aircraft for certain altitudes and air speeds. A model for the firing lead angle is developed for cases when the distribution of hits is normal and the firing angle is from 20 degrees to 160 degrees. probabilities of hit for single and multiple shots at various altitudes are calculated. Tables are given showing the probability of hits and kill for targets flying at high speed above 500 feet from ground level.

• 한국위성정보통신학회논문지
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• 제6권1호
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• pp.37-44
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• 2011

2010년 6월 26일에 발사된 통신해양기상위성(천리안)은 Ka-대역 위성통신, 정지궤도 해양관측, 그리고 기상관측을 위한 탑재체를 가지고 있다. 정지궤도상의 위성을 효과적으로 운용하기 위해서 위성 임무운영 개념을 정립하여 이를 위성관제시스템의 개발 초기 단계부터 적용하였다. 천리안 위성의 임무운영은 일별, 주별, 월별 그리고 계절별 운영으로 구분된다. 위성의 일별운영은 임무계획, 명령계획 및 전송, 원격측정 데이터 처리 및 분석, 위성 거리측정 및 궤도결정, 위성의 궤도 및 이벤트 예측, 그리고 휠 오프로딩 파라미터 계산으로 구분된다. 위성의 주별 운영으로는 화요일에 남북방향 위치유지조정, 목요일에 동서방향 위치유지조정으로 구분된다. 월별운영으로는 위성의 온보드 오실레이터를 갱신하기 위한 비행역학 파라미터 계산과 위성으로의 전송이 수행되며 계절별 운영으로 봄과 가을에는 지구가 태양을 가리는 식에 관련된 위성운영을 수행한다. 이 논문에서는 통신해양기상위성이 발사된 후 약 3개월에 걸친 궤도 내 시험 기간 중에 이루어진 위성관제시스템의 주요 기능들에 대한 운영검증을 기술한다. 이 기간 중에 위성관제시스템의 대부분 기능이 성공적으로 검증되었으며 천리안 위성관제시스템은 위성의 설계 수명기간인 7년 또는 위성이 수명을 다하는 그 이후까지 계속 사용될 예정이다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 C
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• pp.1331-1333
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• 1999

In Haenam-Cheju HVDC link several modes of operations and controls are provided, which are constant frequency control, constant power control and constant current control. This paper describes basic control action of converters under three control modes and shows EMTDC simulation results at ground fault and steady state respectively.

• Journal of Biosystems Engineering
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• 제25권3호
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• pp.195-202
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• 2000

This study was conducted to recognize a possibility that cone index can be used as a means of evaluating the tillage workability. Cone indexes were measured every 24 hours after rainfall at the experimental plots, and the rotary and plowing operations were conducted at the same time. The workability was evaluated on a basis of three categories of good, fair and poor depending on the quality of the performed works. Although the workability was affected by many factors such as soil type, moisture content ground slope and weather condition, the duration and amount of rainfall were of most influence. Results of the study showed that a good workability was resulted from the cone indexes greater than an average of 552 kPa for rotary operations and 671 kPa for plowing operations. Fair work was obtained with cone indexes greater than an average of 331 kPa for rotary operations and 459 kPa for plowing operations. The cone indexes less than an average of 171 kPa and 149 kPa resulted in poor workabilities for rotary and plowing operations, respectively. The experimental results may provide a general guideline for evaluating the tillage workability by cone index.

• 한국항공운항학회지
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• 제26권2호
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• pp.116-122
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• 2018

Due to the opening of Incheon International Airport Terminal 2, the operation range of ground operators is expanding and the workload is increased, which may cause a deterioration of the operation quality. Airline and airport corporations are concerned about safety delays as well as delays in flight due to delays in operations. Air traffic demand at Incheon International Airport is expected to increase steadily in the future. Therefore, this study intends to derive quality improvement plan by investigating the perception of stakeholders about the status of fishing service in order to improve service quality of Incheon airport ground handling company. The results of the analysis are expected to be used as basic data for improving quality of service.

• 한국항공운항학회지
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• 제27권4호
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• pp.27-36
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• 2019

An accurate trajectory prediction is a key to the safe and efficient operations of aircraft. One way to improve trajectory prediction accuracy is to develop a model for aircraft ground speed prediction. This paper proposes a generative model for posterior aircraft ground speed prediction. The proposed method fits the Gaussian Mixture Model(GMM) to historical data of aircraft speed, and then the model is used to generates probabilistic speed profile of the aircraft. The performances of the proposed method are demonstrated with real traffic data in Incheon Flight Information Region(FIR).