• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2000년도 한국우주과학회보 제9권2호
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• pp.50-50
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• 2000

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• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2002년도 한국우주과학회보 제11권2호
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• pp.30.2-30
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• 2002

• 충청수학회지
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• 제36권4호
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• pp.245-253
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• 2023

Let G be a semialgebraic group not necessarily compact. In this paper, we prove that the orbit space of every proper semialgebraic G-set has a semialgebraic structure.

• 천문학회보
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• 제35권2호
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• pp.46.1-46.1
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• 2010

This work is a part of our project to establish a Website which provides a list of magnetic clouds (MCs) identified by WIND and ACE spacecraft. MCs are characterized by their magnetic fields that are well described by magnetic flux rope structures, whereas interplanetary coronal mass ejections (ICMEs) are interplanetary manifestations of coronal mass ejections (CMEs), usually identified by differences of plasma and magnetic field characteristics from those in the background solar wind. It is widely accepted that, while MCs are generally identified within ICMEs, the number of MCs are significantly lower than the number of ICMEs. In our effort to identify MCs, however, we have found that there was a big problem in identification method of MCs in previous works. Generally speaking, most of the previous surveys failed in identifying MCs which encounter the spacecraft at large distances from the MC axis, or near the surface of MC structures. In our survey, MCs are identified as the region of which magnetic fields are well described by appropriate flux rope models. Thus, we could selected over 45 MCs, in 1999 solar wind data for instance, while 33 ICMEs are listed in the Website of the ACE Science Center reported by Richardson and Cane.

• 한국공간정보시스템학회:학술대회논문집
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• 한국공간정보시스템학회 2004년도 춘계 학술발표회 논문집 제1권1호(통권1호)
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• pp.75-82
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• 2004

Many researcher's efforts have made a significant advancement of space frame structure with various portion, and it becomes the most outsanding one of space structures. However, with the characteristics of thin and long term of spacing, the unstable behavior of space structure is shown by initial imperfection, erection procedure or joint, especially space frame structure represents more. This kind of unstable problem could not be set up clearly and there is a huge difference between theory and experiment. Moreover, the discrete structure such as space frame has more complex solution, this it is not easy to derive the formulation of design about space structure. In this space frame structure, the character of rise-span ratio or load mode is represented by the instability of space frame structure with initial imperfection, and snap-through or bifurcation might be the main phenomenon. Therefore, in this study, space frame structure which has a lot of aesthetic effect and profitable for large space covering single layer is dealt. And because that the unstable behavior due to variation of inner force resistance in the elastic range is very important collapse mechanism, I would like to investigate unstable character as a nonlinear behavior with a geometric nonlinear. In order to study the instability. I derive tangent stiffness matrix using finite element method and with displacement incremental method perform nonlinear analysis of unit space structure, star dome and 3-ring star dome considering rise-span $ratio(\mu}$ and load $ratio(R_L)$ for analyzing unstable phenomenon.

• International Journal of Aeronautical and Space Sciences
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• 제16권4호
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• pp.590-601
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• 2015

This paper gives an overview of research on the field of structure vibration-attitude coordinated control of spacecraft. First of all, the importance of the technology has been given an introduction, and then later the research progress of space structure dynamics modeling, research progress of structure vibration-attitude coordinated control of flexible spacecraft have been discussed respectively. Finally, future research on application of structure vibration-attitude coordinated control of spacecraft has been recommended.

• 한국조경학회지
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• 제15권2호
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• pp.43-56
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• 1987

The concept of ‘Open Space’ is conceived to be very valuable subject of interest in developing modern settlement system. In Korea, many new and old residential sites have been developed or renewed to fulfil the housing demands. And such trends seem to continue for the time being. What is more, the requirments for more comfortable residential environments, that is deeply concerned with ‘Open Space’, inorease gradually. As a basis for designing more efficent residential environments to fit Korean morden life style, self - grown, traditional and agricultural villages are studied. This study is concenturated on the Open Space System with its socio - cultural and physical backgrounds. For this, data and materials are some widely collected and are analysed focused on the systems and structures of ‘Open Spaee’. Some results from this study are summarized as follow ; 1. It is assumed that the number of houses per village is around 60, and that its area reaches to the radious of 3-4km. 2. ‘POONGSU’is a generally adopted theory based on natural elements like mountians, waters, and orientations when locating villages and composing their spatial structures. As a result of this, the basic structures of villages and Open Space are defined. 3. Circulation system is integrated to the hierachyal order system ; that is, Passing Road \longrightarrowEntry Road\longrightarrowCentral Read\longrightarrowDisperse and Access Road. 4. The natural and agricultural land uses are overlapped with diverse outdoor activities - religious services, play and recreation, relaxation, etc - without any physical modification. 5. At each villages, several artificial and spot - like green facilities are found. And distinctive functions, meanings, and locationalities are given to each of them. On that, they become a visual and psychological centers of each village. 6. In addition to its basic function of circulation, Central Road takes the sence of place for outdoor activities. Because of this charactor, it plays an important role of activating the village life and binding the various Open Space elements.

• 천문학회보
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• 제41권1호
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• pp.35.1-35.1
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• 2016

Nearby galaxy clusters and their surrounding regions represent the current endpoint of evolution galaxy cluster evolution. We present a new catalog of 1589 galaxies, what we call Extended Virgo Cluster Catalog (EVCC), in wider area of the Virgo cluster based on the Sloan Digital Sky Survey (SDSS) Data Release 7. The EVCC covers an area 5.2 times larger than the footprint of the classical Virgo Cluster Catalog, and reaches out to 3.5 times the virial radius of the Virgo cluster. The EVCC contains fundamental information such as membership, morphology, and photometric parameters of galaxies. The EVCC defines a comprehensive galaxy sample covering a wider range in galaxy density that is significantly different from the inner region of the Virgo cluster. It will be the foundation for forthcoming galaxy evolution studies in the extended Virgo cluster region, complementing ongoing and planned Virgo cluster surveys at various wavelengths. We also present the large scale structures in the field around the Virgo cluster. We identified seven galaxy filaments and one possible sheet in three dimensions of super-galactic coordinates based on the HyperLEDA database. By examining spatial distribution and Hubble diagram of galaxies, we found that six filaments are directly associated with the main body of the Virgo cluster. On the other hand, one filament and one sheet are structures located at background of the main body of Virgo cluster. The EVCC and the filament structures will be the foundation for forthcoming studies of galaxy evolution in various environments as well as buildup of the galaxy cluster at z ~ 0, complementing ongoing and planned Virgo cluster surveys at various wavelengths.

• 한국공간구조학회논문집
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• 제9권2호
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• pp.65-75
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• 2009

스팬 30m 이상을 갖는 건축물로 한정하여, 1960년대 이후 건립된 국내 공공 대공간 건축물의 발달과정과 건립특성에 대하여 연구하였다. 국내 대공간 건축의 용도와 규모의 현황을 살펴보고 구조방식이 건립된 건축물에 미치는 영향을 살펴보고자 한 것이다. 연구결과, 1980년대-90년대에는 스팬 40-70m 규모의 체육시설이 집중적으로 건립되었으나 2000년 이후에는 용도가 다양화되면서 대규모의 컨벤션센터 건립이 다수 이루어지고 있는 것으로 나타났다. 또한 초기 독특한 구조형태와는 달리 80년대에는 입체트러스가 보편적으로 활용되었고, 2000년 이후에는 형태효과를 고려하여 구조체를 고안하거나 새로운 구조시스템을 활용하는 시도가 보여지고 있다.

• 천문학회보
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• 제37권1호
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• pp.95.1-95.1
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• 2012

Halo coronal mass ejections (HCMEs) are major cause of geomagnetic storms and their three dimensional structures are important for space weather. In this study, we compare three cone models: an elliptical cone model, an ice-cream cone model, and an asymmetric cone model. These models allow us to determine the three dimensional parameters of HCMEs such as radial speed, angular width, and the angle (${\gamma}$) between sky plane and cone axis. We compare these parameters obtained from three models using 62 well-observed HCMEs from 2001 to 2002. Then we obtain the root mean square error (RMS error) between maximum measured projection speeds and their calculated projection speeds from the cone models. As a result, we find that the radial speeds obtained from the models are well correlated with one another (R > 0.84). The correlation coefficients between angular widths are less than 0.53 and those between ${\gamma}$ values are less than 0.47, which are much smaller than expected. The reason may be due to different assumptions and methods. The RMS errors of the elliptical cone model, the ice-cream cone model, and the asymmetric cone model are 213 km/s, 254 km/s, and 267 km/s, respectively. Finally, we discuss their strengths and weaknesses in terms of space weather application.