• 한국우주과학회:학술대회논문집(한국우주과학회보)
• /
• 한국우주과학회 2008년도 한국우주과학회보 제17권2호
• /
• pp.25.3-26
• /
• 2008

The direct way to the moon is to start from the parking orbit by using impulsive thruster In previous domestic research, the direct way has been studied by using a single impulsive shot. However, when a single impulsive shot occurs to go into a Translunar orbit, gravity losses occur because thruster is not impulsive shot but the finite burns and it causes the gravity losses. To make up for the weak point of a single impulsive shot, this paper divides TLI (Trans Lunar Injection) into several small burns. Therefore, departure loop trajectory and the Translunar trajectory. This method is useful not only to reduce the gravity losses but also to check the condition of satellite. By using this method, this paper demostrates the optimized trajectory from Earth parking orbit to lunar mission orbit which minimizes the fuel, and the SNOPT (Sparse Nonlinear OPTimizer software) is used to find optimal solution. Also, this paper provides lunar mission profile which includes the mission schedule when TLI, LOI (Lunar Orbit Insertion) maneuvers occur, a mount of fuel when thruster is used and other mission parameters.

• 한국국방경영분석학회지
• /
• 제30권1호
• /
• pp.153-167
• /
• 2004

This study focuses on building the wartime air operation model to evaluate the airfield capability. There are some uncertainties in the process of air operation such as mission flying time, turn around time, mission damage or kill rate, weather condition, and so on. Airplanes, on the way to the airbase after completing mission flight, may have been in queue on the holding point due to the unusable condition of airfield. And then, they may sometimes need to go other airbases due to the shortage of fuel. Under those uncertainties, this model is to evaluate the airfield capability in the wartime air operation using simulation.

• 한국도서관정보학회지
• /
• 제28권
• /
• pp.479-503
• /
• 1998

This paper examines the effects of the Internet on the librarianship and how the changing roles of libraries and librarians are reshaping the way they serve the users in the information age. Each area of operations and services in a so-called Digital/Electronic Library, which is a phenomenon occurring now not sometime later in the future, is reviewed. The importance of keeping in mind the library' main mission of providing a service, i.e. access to information, is stressed as the pivotal point of librarianship in this global society influenced by the presence of the Internet.

• 대한임베디드공학회논문지
• /
• 제18권2호
• /
• pp.75-80
• /
• 2023

Unmanned drone stations for automatic charging have been developed in order to overcome the flying time limitation of rotary wing drones. Since the drone stations is an unmanned operating system, each of the drones will be required to have a high degree of landing accuracy. Drone precision landing has been mainly studied depended on image processing technologies, but the image processing systems make several problems, such as the mission weight, the drone cost, and the development complexity increases, and the flight time decrease. Thus, this paper researched accuracy of precision landing based on RTK (real time kinetics) for rotary wing drones. For the experiments of RTK based precision landing, a drone repeatedly performed three missions. The survey accuracies of the RTK about missions respectively were set as 0.3, 0.2, and 0.1 meters. Each mission has one take-off point, two way-points and one landing-point, and was repeated ten times. The experiment results revealed landing error distance means of around 0.258, 0.12 and 0.057 meters on each of RTK setting.

• 항공우주시스템공학회지
• /
• 제13권2호
• /
• pp.1-9
• /
• 2019

본 논문에서는 고고도 장기체공 무인항공기의 임무 비행을 위한 방향축 유도, 제어 알고리즘에 대해 기술 하였다. 먼저 방향축 제어 알고리즘은 임무 기간 중 무인항공기가 전진비행을 할 수 없을 맞바람에 대해 제어 변수를 전환하는 알고리즘을 설계하였다. 유도법칙은 항로점 비행을 위해 Fly-over, Fly-by, Hold 속성에 대한 각각의 알고리즘을 적용하였다. 무인항공기의 비선형 시뮬레이션을 통해 각 유도, 제어 알고리즘의 설계 결과를 확인하였다. 본 연구는 설계 결과를 토대로 실제 임무 비행을 수행하는 것을 목적으로 한다. 따라서 본 연구 내용을 기반으로 비행 시험을 통해 설계한 유도 제어 알고리즘의 비행 운용성을 확인하였다.

• 해양환경안전학회지
• /
• 제27권6호
• /
• pp.867-874
• /
• 2021

4차 산업시대를 맞이하여 많은 공학 분야에서 IoT(Internet of Things)기술의 연계는 매우 중요한 쟁점이다. 최근 조선소에서도 디지털 조선, 스마트 팩토리 등의 개념을 구체화하고 있는 추세이다. 한편 자동차, 비행기 등에서 자율주행을 구현하는 연구는 매우 활발하고 일정 부분 상용의 형태로 나타나고 있다. 본 연구는 오픈 소스 아두파일럿 기반의 FC(Flight Controller) 및 RTK(Real Time Kinematic) GPS(Global Positioning System)를 이용하여 자율 주행 임무를 수행하는 보트의 주행성에 관한 연구로서 잔잔한 호수에서 실해역 실험을 수행하였으며 보트의 임무는 특정한 지점을 자율주행한 후 홈 위치로 스스로 돌아오는 과정에 대한 조종성 평가이다. 주어진 속도에서 기설정된 임무 궤적과 실 운항 궤적에 따른 차이를 분석하고 시스템의 보트 적용성에 대한 일련의 연구를 수행하였다. 또한 4개의 프로펠러를 가지는 OmniX 선체의 주행성을 분석하였으며 최대 48%의 주행 추적성 향상을 확인하였다.

• 한국항해항만학회:학술대회논문집
• /
• 한국항해항만학회 2006년도 Asia Navigation Conference
• /
• pp.3-10
• /
• 2006

Recently it is coming to be hish reality on visual system in ship-handling simulator depending on the technical development of 3D computer graphics. Even with high reality, it is possible that visual information presented seafarers through screen or display is not equivalent to the real world. In docking maneuvering, visual targets or obstructs are sighted close to ship's operator or within few hundred meters, so it might be possible to affect visual information such as the difference between both eyes' and single eye's visual sight. Because it is not possible to perceive of very slow ship's movement by visual in case of very large vessels, so the Doppler Docking SONAR and/or Docking Speed and Distance Measurement Equipment were developed and applied for safety docking maneuvering. By the way, the simulator training includes the ship's maneuvering training in docking, but in Ship-handling Simulator and also onboard, there are some limitations of perception of ship's movement with visual information. In this paper, perception of ship's movement with visual system in Ship-handling Simulator and competition of performances of visual systems that are conventional screen type with Fixed Eye-point system and Mission Simulator. We got some conclusions not only on the effectiveness for visual system but also on the human behavior in docking maneuver.

• 한국군사과학기술학회지
• /
• 제17권3호
• /
• pp.304-310
• /
• 2014

Based on atmosphere weather data by balloon in Osan and Gwangju area, if icing condition occurs in weather environment of altitude range where helicopter is operated was analyzed in quantitative way. Yearly icing occurrence frequency for daytime during recent three years was average 102 days in Osan, average 91 days in Gwangju. Icing weather environment to highly affect operation of helicopter varies a little according to analysis methods but icing intensity at MDT level was calculated in all the methods, and 14.5~38 times was suggested in Osan; 2.5~30 times in Gwangju. Icing at MDT level was calculated in common in all the analysis methods through wide periods such as Jan., Feb., Mar., and Nov. in Osan. In Gwangju, icing at MDT level was suggested focusing on Jan. only. Therefore, military helicopter developed in Korea is required to strive obtaining certificate of airworthiness about icing condition at MDT level for implementation of perfect operational mission and safe operation.

• 해양환경안전학회:학술대회논문집
• /
• 해양환경안전학회 2000년도 International Symposium:on the Maritime Management Systems for Safer and Cleaner Seas in the New Millennium
• /
• pp.14-25
• /
• 2000

Should the Korea Maritime Police Agency (KMPA) be a comprehensive, multi-functional organization for a unique on-scene service at sea, as in the case of the U.S. Coast Guard, or should it be simply a water police agency, confining its mission only to law enforcement? The argument about enlarging or limiting KMPA's function has been and will be repeated. In this paper, Lee Sangjib highlights the internal and external issues facing KMPA, stemming partly from deficiencies of its struggles for advancement of the organization and partly from shortcomings of political support for it. In this regard, he urges KMPA to practise a scientific management system for maximizing cost-effectiveness of its administrative resources and for maintaining its identity and characteristics as a lead maritime agency. In addition, he also suggests that KMPA adopt the Total Quality Management System for quality improvements in services and greater efficiency in its organization structure to meet the future competition in the changing political and legal environment. He further recommends the proactive, non-regulatory 'Prevention Through People' program, pioneered by the U.S. Coast Guard, as a way of changing KMPA's existing lopsidedly legalistic culture. He concludes by providing a 6-point vision statement for KMPA from the standpoint of favoring enlarging the function of KMPA.

• 동남아시아연구
• /
• 제21권3호
• /
• pp.1-42
• /
• 2011

In terms of seaborne contacts of Vietnamese court with foreign countries had two directions in the 19th century. One was with Island Southeast Asian ports such as Singapore, Malacca, Penang, Batavia, and Manila. The other direction was to Canton. The Canton contact of Vietnam again can be interpreted as one of the two directions of Vietnamese contact with China. The inland route far to Beijing was based on the political and diplomatic consideration, while the closer route to Canton by the court vessels was more for the economic consideration as the case for the contact with the Island Southeast Asia. In this article, author discusses three issues to illuminate the nature of the trips of the court vessels of the Nguyễn dynasty to Canton. First is to clarify detail itinerary of the trip from the Thuận An Estuary to the City of Canton via Đà Nãng and Hanan. Unlike to the Western ships that visited Canton but anchored at the Huang Fu, Vietnamese square-rigged/copper-bottomed ships sailed up the Pearl river to the Guangzhou city front to stay for four or five months before they returned to Vietnam. In the second chapter, various kinds of observation of the Vietnamese officials are discussed. If the objects of the observation are divided into two categories, one is the world Westerners in Canton, and the other is the world of Chinese. In a same place, Canton, the Vietnamese officials could have enough chance to compare the two worlds clearly. An important consequence for the Vietnamese officials was to conclude that the mechanical technology of the Westerners was better than that of Chinese. This kind of conclusion led the Vietnamese court to send court personnels to learn Western technologies and languages in the port cities of Island Southeast Asia and to enlarge contacts with them. In the last chapter, author tries to find out the items that the Vietnamese mission purchased in Canton in exchange to the Vietnamese products. The items that the Vietnamese mission purchased included ceramics, silk, books, and medicines. With the support of the Chinese settlers in Vietnam the mission was able to be involved in the deal of illegal items such as opium, and possibly some kinds of precious ginseng from Korea. Overall, the process of the itinerary, observation, and purchase during the trip to Canton was the way to form the new point of view of Vietnamese intellectuals towards China standing from the side of Westerners. To the Vietnamese who experienced both Canton/Macao and the Western worlds in the port cities of Island Southeast Asia China was not the only center of the world, nor the Westerners could be looked down as the barbarians. In Canton, a peripheral region looked from the imperial capital Beijing, but the most internationalized city of China at that time, Vietnamese officials were training themselves to overcome China.