• Journal of Astronomy and Space Sciences
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• 제32권3호
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• pp.269-279
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• 2015

Future space missions will have larger telescopes in order to look deeper into space while improvising on spatial resolution. The primary mirrors for these telescopes will be so large that using a monolithic mirror will be nearly impossible because of the difficulties associated with its fabrication, transportation, and installation on a launch vehicle. The feasibility of launching these huge mirrors is limited because of their small launch fairing diameter. The aerodynamic shape of the fairing requires a small diameter, but the height of the launch vehicle, which is available for designers to utilize, is larger than the fairing diameter. This paper presents the development of an axial deployment mechanism based on the screw jack principle. The mechanism was designed and developed, and a prototype was constructed in order to demonstrate a lab model.

• 한국안전학회지
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• 제21권2호
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• pp.143-149
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• 2006

본 논문은 2차원 동적 진동문제를 공간-시간 유한요소법으로 해석하고 있다. 공간-시간 유한요소법은 공간만 분할하는 재래식 유한요소해석에 비해 보다 해를 빠르고 쉽게 얻을 수 있다. 상대적으로 큰 시간간격에 대해서 공간과 시간을 동시에 분할하는 공간-시간 유한요소 근사법을 제시한다. 가중잔차법으로 공간-시간 영역에 대해 유한요소법을 정식화하였으며 선형 사변형 공간-시간 유한요소를 선택하여 해의 안정성에 관하여 언급하였다. 일반적 동적문제에서는 상대적인 큰 시간간격으로 인하여 해의 불안정을 야기 시키고 있으나 본 연구에서는 수치의 안정성을 보여주고 있다. 비구조 공간-시간 유한요소법은 재래식 수치해석에서 흔히 발생하는 해의 불안정성에 대한 결점을 보완함은 물론 효과적인 계산방법을 지니고 있다. 이 방법의 효율성을 위해 수치예제들을 제시하였다.

• 디지털포렌식연구
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• 제12권3호
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• pp.27-38
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• 2018

최근 디지털 데이터의 양이 급격하게 증가함에 따라 대용량 저장 공간의 필요해지고 있다. RAID는 이러한 대용량 저장 공간을 관리할 수 있는 시스템이다. Windows에서 제공하는 저장소 공간은 소프트웨어 RAID의 일종이다. 저장소 공간은 Windows 8, Windows Server 2012 버전부터 지원되었으며 해당 기능에 대한 분석이 기존에 이루어져 있지 않다. 저장소 공간을 이용한 시스템을 분석하기 위해서는 저장소 공간 기능에 대한 분석과 가상 디스크 재구성 방법에 대한 연구가 이루어져야 한다. 본 논문에서는 기존 RAID의 레이아웃에 대해 간단히 설명하고 소프트웨어 RAID인 저장소 공간의 구성 방식과 메타데이터를 설명하고 구성 방식별로 가상 디스크의 재구성 방법을 제시하고 실험을 통해 이를 검증하였다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2001년도 Proceeding of KIN-CIN Joint Symposium 2001 on Satellite Navigation/AIS, lntelligence , Computer Based Marine Simulation System and VDR
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• pp.153-168
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• 2001

In the country where the population concentrates in the metropolis with the narrow land, development of th ocean space is necessary. Recently, mega-float offshore structure is studied as one of the effective utilization of the ocean space. And very large floating structure are now being considered for various applications such as floating airports, offshore cities and so on. This very large structure is relatively flexible compared with real floating structures like large ships. when we estimate dynamic responses of these structures in waves, the elastic deformation is important, because vertical dimension is small compared with horizontal. And it is necessary to examine the effect of ocean wave eternal force received from the natural environment. In this study, the mat-type large floating structure is made to be analytical model. And the analysis of the dynamic response as it receives regular wave is studied. The finite element method is used in the analysis of structure part of this model. And the analysis is carried out using the boundary element method in the fluid part. In order to know the characteristics of the dynamic response of the large floating structures, effects of wavelength, bending rigidity of the structure, water depth, and wave direction on dynamic response of the floating structure are studied by use of numerical calculation.

• 천문학회보
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• 제37권1호
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• pp.75.2-75.2
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• 2012

Turbulence is ubiquitous in astrophysical fluids such as the interstellar medium and intracluster medium. To maintain turbulent motion, energy must be injected into the fluids. In turbulence studies, it is customary to assume that the fluid is driven on a scale, but there can be many different driving mechanisms that act on different scales in astrophysical fluids. We expect different statistical properties of turbulence between turbulence with single driving scale and turbulence with double driving scales. In this work, we perform 3-dimensional incompressible MHD turbulence simulations with energy injection in two ranges, 2${\surd}$12 (large scale) and 15

• 한국항해학회지
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• 제24권1호
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• pp.85-95
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• 2000

In the country where the population concentrates in the metropolis with the narrow land, development of the ocean space is necessary. Recently, mega-float offshore structure has been studied as one of the effective utilization of the ocean space. And very large floating structures are now being considered for various applications such as floating airports, offshore cities and so on. This very large structure is relatively flexible compared with real floating structures like large ships. when we estimate dynamic responses of these structures in waves, the elastic deformation is important, because vertical dimension is small compared with horizontal. And it is necessary to examine the effect of ocean wave external force received from the natural environment. In this study, the mat-type large floating structure is made to be analytical model. And the analysis of the dynamic response as it receives regular wave is studied. The finite element method is used in the analysis of structural section of this model. And the analysis is carried out using the boundary element method in the fluid division. The validity of analysis method is verified in comparison with the experimental result in the Japan Ministry of Transport Ship Research Institution. In order to know the characteristics of the dynamic response of the large floating structures, effects of wavelength, bending rigidity of the structure, water depth, and wave direction on dynamic response of the floating structure are studied by use of numerical calculation.

• 천문학회보
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• 제46권2호
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• pp.68.1-68.1
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• 2021

We study galaxy evolution with the large-scale environment with confirmed galaxy clusters from multi-object spectroscopy (MOS) observation. The observation was performed with Inamori Magellan Areal Camera and Spectrograph (IMACS) mounted on the 6.5 m Magellan/Baade telescope in Las Campanas Observatory. With the MOS observation, we spectroscopically confirm 34 galaxy clusters, including three galaxy clusters discovered in Kim et al. (2016) and 11 of them have halo mass of > 10^14.5 M_◉. Among the confirmed clusters, 12 galaxy clusters are part of large-scale structure at z ~ 0.9, and their size stretches to 40 Mpc co-moving scale. In this study, we checked the 'web feeding model,' which postulates that more linked (with their environment) galaxy clusters have less quenched populations by investigating the correlation between properties of confirmed galaxy clusters and the large-scale structure environment. Lastly, we found that galaxy clusters that make up the large-scale structure have larger and widely spread values of total star formation density (ΣSFR/M_halo) than typical clusters at similar redshifts.

• 한국초전도ㆍ저온공학회논문지
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• 제19권1호
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• pp.13-16
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• 2017

Water issue, especially water pollution, is a serious issue of 21st century. Being an significant technique for securing water resources, superconducting magnetic separation wastewater system was indispensable. A large bore conduction-cooled magnet was custom-tailored for wastewater treatment. The superconducting magnet has been designed, fabricated and tested. The superconducting magnet was composed of NbTi solenoid coils with an effective horizontal warm bore of 400 mm and a maximum central field of 2.56T. The superconducting magnet system was cooled by a two-stage 1.5W 4K GM cryocooler. The NbTi solenoid coils were wound around an aluminum former that is thermally connected to the second stage cold head of the cryocooler through a conductive copper link. The temperature distribution along the conductive link was measured during the cool-down process as well as at steady state. The magnet was cooled down to 4.8K in approximately 65 hours. The test of the magnetic field and quench analysis has been performed to verify the safe operation for the magnet system. Experimental results show that the superconducting magnet reached the designed magnetic performance.

• 한국환경과학회지
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• 제23권7호
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• pp.1349-1358
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• 2014

This study suggests plan of green space management based on the result of research apprehending the characteristic through sorting types of city thermal environment targeting summer which thermal pollution is the most serious. Considering anthropogenic heat, development level of wind road, thermal environment, as a result of types of thermal environment process, it is appeared 36 types, and 10 types is relevant of this research subject. Type I-1, size of building is large, artificial covering area is wide, and thermal load of anthropogenic heat is high, type II-1, development condition of wind road is incomplete as IIlevel, entering cold air is difficult and thermal management and improvement is needed area. Type III-1, scale is large and it is area of origin of cold air, development level of wind road is mostly favorable, type III-2 is revealed as smaller scale than III-1, and small area of origin of cold air. Type IV, anthropogenic heat is $81{\sim}150W/m^2$, average, but development function of wind road is very favorable. Type V, large area of thermal load and the origin of cold air are distributed as similar ratio, and level of development function of wind road is revealed as II level. According to standard of type classification of thermal environment, as a result of suggesting plan of green space management and biotops area ratio, type I-1 is buffer green space and waterway creation, goal biotops area ratio 35%, type II-1 afforestation in site and goal biotops area ratio 40%, type III-1, preservation plan to display the current function continuously is requested. Type IV suggests afforestation of stream current, and type V suggests quantitative increase of green space and goal biotops area ratio 45%.

• 화약ㆍ발파
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• 제19권1호
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• pp.71-84
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• 2001

Korean peninsula has the most mountainous areas such as mountains and hilly country, and it is surrounded by the sea on all sides but one. In this respect, a large scaled construction works have frequently been conducted. However, it is not easy to porform a large scale blasting work without giving any harm to houses or facilities nationwide. Therefore, blasting work becomes more closely related to maintenance thing due to the development of the downtown or a large structure for key facilities. Many researches on blast in the open space and tunnel blasting have been conducted. On the contrary, research on underwater blasting operations is comparatively scanty even though much more necessity of marine development is required. In this respect, this study aims to investigate the characteristics of underwater blasting operations and to make a comparative study with blast in the open space. As a result of examining into the characteristics during underwater blasting operations, the around oscillation in case of underwater blasting operations shows significantly low compared to that in case of blast in the open space, and this means that much more cautious altitude must be taken in designing underwater blasting operations compared to the design of blast In the open space. As a result of analysis on the difference between a square root and a cube root In the equation of estimating oscillations in the actual site, it is shown that it is shown to apply a square root for the estimation of oscillation at 60 meters in case of underwater blasting operations and at 22 meters case of general blast in the open space.