• 한국항공우주학회지
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• 제36권12호
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• pp.1216-1221
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• 2008

본 논문에서 고려된 저궤도 위성은 고정형 태양 전지판을 가지기 때문에 낮구간(daylight) 동안에 태양전지판이 태양지향(sun-pointing) 자세를 유지하고, 관측 임무 수행을 위해 태양 전지판 방향과 반대방향에 위치한 탑재체가 지구지향(nadir-pointing)이 되도록 자세를 변경한다. 이 때 낮기간의 대부분을 차지하는 태양지향 자세에서는 위성 패널(panel)로 입사하는 외부 열환경 요인이 지구 복사열과 알비도(Albedo)이기 때문에, 비교적 안정적인 열환경 조건을 가지고 있다. 이에 반하여, 관측 임무를 수행하는 궤도 10% 정도의 지구지향 자세에서는 위성의 열환경 조건에 가장 지배적인 영향을 주는 태양광이 위성 패널에 영향을 준다. 비록 위성이 비교적 짧은 시간 동안에 지구 지향의 자세를 유지하지만, 이러한 열한경 조건의 변화 때문에 위성의 열설계에서 지구지향의 임무 자세에 따른 열적 영향에 대한 검토가 필요하다. 본 연구에서는 열해석 모델에 관측 임무 구간 동안의 지구지향 자세를 반영한 열해석 결과를 통하여 그 영향을 알아보았다.

• 한국컴퓨터정보학회논문지
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• 제16권9호
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• pp.11-18
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• 2011

본 논문에서는 워게임에서 가상군 개체가 주어진 임무와 상황에 따라서 행위를 계획하여 실행하는 새로운 자동계획 기법을 제안한다. 임무를 부여받은 가상군은 먼저임무를 완료하는데 필요한 과업을계획한 후 각 과업을달성 하는데 필요한 행위를 계획하여 실행한다. 과업과 행위는 계층적으로 구성되어 있으며 이를 시작하는데 필요한 개시조건과 완료를 확인하는 종료조건을 포함한다. 가상군은 계획된 과업에 대하여 과업수행에 필요한 행위들의 개시조건이 일정치 이상으로 만족되는지 체크하고 만족되면 행위를 수행하며 이 행위는 종료조건이 만족될 때까지 지속된다. 종료조건이 만족된 경우 계획된 다음 행위에 대하여 개시조건을 체크하여 행위하는 과정이 반복된다. 상황이 변화되어 계획된 행위의 개시조건이 만족하지 못하면 퍼지규칙으로 이를 판단하여 새로운 결정을 내릴 수 있다. 제안한 방법을 구현해 특정 시나리오 상황에서 실험한 결과 제안한 방법이 주어진 과업에 대하여 올바른 계획을 스스로 생성함을 보였고 또한 상황 변화에 대하여 능동적으로 대처하는 모습을 볼 수 있었다. 본 논문에서 제안한 방법을 더 발전시키면 보다 더 자율적 행위를 수행하는 가상군을 모의할 수 있을 것이다.

• Strategy21
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• 통권34호
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• pp.178-206
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• 2014

The battlefield environment in the maritime has been changed by advanced IT technology, variation of naval warfare condition, and developed military science and technology. In addition, state-of-the-art surface combatants has become to multi-purpose battleship that is heavily armed in order to meet actively in composed future sea battlefield condition and perform multi-purpose missions as well as having capability of strategic strike. To maximize the combat strength and survivability of ship, it is not only possible for Zumwalt(DDG-1000) class combatant to conduct multi-purpose mission with advanced weapon system installation, innovative hull form and upper structure such as deckhouse, shipboard high-powered sensor, total ship computing environment, and integrated power control but it was designed so that can be installed with energy based weapon systems in immediate future. Zumwalt class combatant has been set a high value with enormous threatening surface battleship in the present, it seems to be expected that this ship will be restraint means during operation in the littoral. The advent of Zumwalt class battleship in the US Navy can be constructed as a powerful intention of naval strength building for preparing future warfare. It is required surface ship that can be perform multi-purpose mission when the trend of constructed surface combatants was analyzed. In addition, shipboard system has been continuously modernized to keep the optimized ship and maximize the survivability with high-powered detection and surveillance sensor as well as modularity of combat system to efficient operation.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2011년도 한국우주과학회보 제20권1호
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• pp.24.4-24.4
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• 2011

Frozen orbit concept is very useful in designing particular mission orbits including the Sun-synchronous and minimum altitude variation orbits. In this work, variety of frozen and Sun-synchronous orbit conditions around the Moon is investigated and analyzed. The first two zonal harmonics of the Moon, J2 and J3, are considered to determine mean orbital elements to be a frozen orbit. To check the long-term behavior of a frozen orbit, formerly developed YonSei Precise Lunar Orbit Propagator (YSPLOP) is used. First, frozen orbit solutions without conditions to be the Sun-synchronous orbit is investigated. Various mean semi-major axes having between ranges from 1,788 km to 1,938 km with inclinations from 30 deg to 150 deg are considered. It is found that a polar orbit (90 deg of inclination) having 100 km of altitude requires the orbital eccentricity of about 0.01975 for a frozen orbit. Also, mean apolune and perilune altitudes for this case is about 136.301 km and 63.694 km, respectively. Second, frozen orbit solutions with additional condition to be the Sun-synchronous orbit is investigated. It is discovered that orbital inclinations are increased from 138.223 deg to 171.553 deg when mean altitude ranged from 50 km to 200 km. For the most usual mission altitude at the Moon (100 km), the Sun-synchronous orbit condition is satisfied with the eccentricity of 0.01124 and 145.235 deg of inclination. For this case, mean apolune and perilune altitudes are found to be about 120.677 km and 79.323 km, respectively. The results analyzed in this work could be useful to design a preliminary mapping orbit as well as to estimate basic on-board payloads' system requirements, for a future Korea's lunar orbiter mission. Other detailed perturbative effects should be considered in the further study, to analyze more accurate frozen orbit conditions at the Moon.

• 천문학회지
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• 제38권2호
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• pp.307-310
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• 2005

The Solar-B is the third Japanese spacecraft dedicated for solar physics to be launched in summer of 2006. The spacecraft carries a coordinated set of optical, EUV and X-ray instruments that will allow a systematic study of the interaction between the Sun's magnetic field and its high temperature, ionized atmosphere. The Solar Optical Telescope (SOT) consists of a 50cm aperture diffraction limited Gregorian telescope and a focal plane package, and provides quantitative measurements of full vector magnetic fields at the photosphere with spatial resolution of 0.2-0.3 arcsec in a condition free from terrestrial atmospheric seeing. The X-ray telescope (XRT) images the high temperature (0.5 to 10 MK) corona with improved spatial resolution of approximately 1 arcsec. The Extreme Ultraviolet Imaging Spectrometer (EIS) aims to determine velocity fields and other plasma parameters in the corona and the transition region. The Solar-B telescopes, as a whole, will enable us to explore the origins of the outer solar atmosphere, the corona, and the coupling between the fine magnetic structure at the photosphere and the dynamic processes occurring in the corona. The mission instruments (SOT/EIS/XRT) are joint effort of Japan (JAXA/NAO), the United States (NASA), and the United Kingdom (PPARC). An overview of the spacecraft and its mission instruments are presented.

• 한국항공운항학회지
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• 제23권4호
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• pp.117-124
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• 2015

RAM (Reliability, Availability and Maintenance) has been applied to design and analysis tools which affects system's operational sustainability and its life cycle cost as RAM-c(2009 DoD). RAM-c plays also an important role to guarantee the system engineering for mission assurance. Reliability is highly related to the probability of system failure. Availability means mission capability or the condition of ready to mission. Maintenance includes both the repair to recover the system in the event of failure/unexpected breakdown and proactive maintenance to prolong the design service life of the system or machinery. It is the purpose that this paper is to analyze and conclude the objective service life of UAV. The more UAV is operated, the less the level of its reliability becomes. Repairing failures and supplying spare parts on time, system reliability could be improved up until the time over target. Applying statistical Weibull distributions, this paper suggests the analysis of the design service life and economic life of UAV based on RAM-c with operational data.

• Strategy21
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• 통권39호
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• pp.198-241
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• 2016

Aircraft carriers: are they national platforms to maximize national interest or just simply paper tigers to be little useful for states' development? To some states such as U.S., U.K, and France, aircraft carriers functioned as national assets which is indispensable to their interest. By contrast, Thailand's aircraft carrier was a dead platform which is useless to its national interest and India's ones were little used on the mission field. What is the mechanism leading to this difference? The key is whether states make aircraft carriers connected to overall national evolution when it comes to establishing military strategy and planning a long-term force structure. Put it another way, conditions to acquire them need to be analyzed regarding two variables-national status(prestige and economic power) and threat(mission)-for the future as well as in the present. The former acquired carriers under the condition of making them becoming national platforms which is balanced with their overall development. However, the latter simply bought them without carefully taking account of economic obstacles, e.g., the poverty rate, when it comes to force planning. At the same time, we should not neglect to identify that states of the former cases might have a hard time in maximizing their key interests if they did not have carriers. Accordingly, conditions on carriers' acquisition need to be carefully examined and a typological theory suggested here could shed light on this process. This theory shows that South Korea's status is eligible to have a necessary and sufficient condition to acquire carriers.

• 경영과정보연구
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• 제22권
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• pp.61-84
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• 2007

This research aims to find the legal classification of non-profit corporation, to check the pattern of non-profit corporation, to examine thoroughly the present condition of non-profit corporation, and to make a good solution of the problems of non-profit corporation. The findings of this study about the present condition of non-profit corporation are as follows. First, there is an unclear understanding of non-profit corporation and an public fund, Second, a board of directors and a founder control an aim of non-profit corporation freely, Third, there is an unclear management of activity and accounts of non-profit corporation, forth, there is an vague mission of foundation, fifth, some of non-profit corporation supported social welfare project for marketing strategy. and the last non-profit corporation made an competition unnecessarily. On the basis of study result, the researcher make some suggestion for an revitalizing of non-profit corporation. First, it is very important of making a clear mission to manage the non-profit corporation. Second, there is an autonomy and neutrality of non-profit corporation. Third, we make an irrational law better, forth, we make a settled the donation culture. and the last it is necessary of make an foundation for international society.

• 천문학회보
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• 제46권2호
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• pp.59.2-59.2
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• 2021

On March 6 2021, Apophis made a close approach to the Earth with a minimum distance of 0.11 AU when the apparent magnitude reached up to V~16. This was the most favorable condition to observe this asteroid until its 2029 encounter. The observations during this apparition were extremely important to determine major physical properties, such as size, rotational state, 3D shape model, surface mineral properties. So, we organized the observation campaign during the 2021 apparition. The main goals of our campaign are to refine the spin state and 3D shape model and check the surface composition variations. The campaign involved dozens of countries and included ground-based photometry and spectroscopy, and spacecraft observations. Our timely observation campaign will provide essential data in planning the operation scenario for the space mission. In this presentation, we will report the preliminary result of the Apophis observation campaign during the 2021 apparition.

• 한국항해학회지
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• 제18권2호
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• pp.41-56
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• 1994

This paper was a part of the risk management in planning a channel. It utilized Korea Marine Training & Research Institutes(KMTRI) which Houses a real-time, full-mission shiphandling simulator to examine the safety of the ship's transit in the planned channel of Asan port. 6 competent Captains participated in this study. The vessel modelled was a 60,000-ton ship. The two variables(factors) examined were environ-mental conditions such as flood-and-ebb current condition and day-and-night condition. The two variables were combined to produce four experimental conditions. To evaluate the safety of the environmental conditions, two categories of performance measures were analyzed. They were vessel's proximity to channel boundary and vessel controalbility. The findings regar-ding the effects of environmental conditions were as follows : - Closest Point of Approach(CPA) to channel boundary was enough for 60,000-ton ship to transit th-rough the channel with 99.999% confidence level. - Closest Point of Approach(CPA) to channel boundary further was under against-current condition than under with-current condition. -Vessel controlability was better under against-current condition than under with-current condition. -Vessel controlability was better under inbound transit than under outbound transit.