• Title/Summary/Keyword: space plane

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Ecliptic Survey for Unknown Asteroids with DEEP-South

  • Lee, Mingyeong;JeongAhn, Youngmin;Yang, Hongu;Moon, Hong-Kyu;Choi, Young-Jun
    • The Bulletin of The Korean Astronomical Society
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    • v.44 no.1
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    • pp.63.2-63.2
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    • 2019
  • Eight hundred thousand asteroids in the solar system have been identified so far under extensive sky surveys. Kilometer to sub-km sized asteroids, however, are still waiting for discovery, and their size and orbital distribution will provide a better understanding of the collisional and dynamical evolution of the solar system. In order to study the number of asteroids which is detectable with 1.6 m telescope and their orbital distribution, we conducted a small observation campaign as a part of Deep Ecliptic Patrol of the Southern Sky (DEEP-South) project, which is an asteroid survey in the southern hemisphere with Korea Microlensing Telescope Network (KMTNet). We observed the ecliptic plane near opposition (2×22×2 field of view centering on α=22h40m31sα=22h40m31s, δ=082258) in August 2018, and identified 464 moving objects by visual inspection. As a result, 266 of 464 moving objects turn out to be previously unknown asteroids, and their signal to noise ratio is below two on numerous occasions. Most of the newly detected objects are main belt asteroids (MBAs), while three Hildas, one Jupiter trojan, and two Hungarias are also identified. In this meeting, we report the differences in the orbital distributions between the previously known asteroids and newly discovered ones using statistical methods. We also talk about the observational bias of this survey and suggest future works.

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SCALED VISUAL CURVATURE AND VISUAL FRENET FRAME FOR SPACE CURVES

  • Jeon, Myungjin
    • Journal of the Chungcheong Mathematical Society
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    • v.34 no.1
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    • pp.37-53
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    • 2021
  • In this paper we define scaled visual curvature and visual Frenet frame that can be visually accepted for discrete space curves. Scaled visual curvature is relatively simple compared to multi-scale visual curvature and easy to control the influence of noise. We adopt scaled minimizing directions of height functions on each neighborhood. Minimizing direction at a point of a curve is a direction that makes the point a local minimum. Minimizing direction can be given by a small noise around the point. To reduce this kind of influence of noise we exmine the direction whether it makes the point minimum in a neighborhood of some size. If this happens we call the direction scaled minimizing direction of C at p ∈ C in a neighborhood Br(p). Normal vector of a space curve is a second derivative of the curve but we characterize the normal vector of a curve by an integration of minimizing directions. Since integration is more robust to noise, we can find more robust definition of discrete normal vector, visual normal vector. On the other hand, the set of minimizing directions span the normal plane in the case of smooth curve. So we can find the tangent vector from minimizing directions. This lead to the definition of visual tangent vector which is orthogonal to the visual normal vector. By the cross product of visual tangent vector and visual normal vector, we can define visual binormal vector and form a Frenet frame. We examine these concepts to some discrete curve with noise and can see that the scaled visual curvature and visual Frenet frame approximate the original geometric invariants.

Asteroid Taxonomic Classification in Photometry

  • Choi, Sangho;Roh, Dong-Goo;Moon, Hong-Kyu;Kim, Myung-Jin;Sohn, Young-Jong
    • The Bulletin of The Korean Astronomical Society
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    • v.45 no.1
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    • pp.47.1-47.1
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    • 2020
  • Multi-band photometry provides an advantage in being able to perform taxonomic classification analysis on a large number of asteroids in a much shorter period of time than spectroscopy. We observed main-belt asteroids using Korea Microlensing Telescope Network (KMTNet) in CTIO during the summer seasons in the southern hemisphere, mostly in December 2015, 2016 and 2017 with two visible photometric systems, SDSS (g, r, i, and z), and Johnson-Cousins (B, V, R, and I). Targets were selected for the asteroids which had already been classified based on Bus-Binzel taxonomy (Bus & Binzel, 2002) and DeMeo taxonomy (DeMeo et al. 2009). Not only the targets but also numerous serendipitously observed asteroids were identified. In summary, 6817 and 5456 known objects, including 307 and 233 already classified asteroids were observed with SDSS and Johnson-Cousins systems, respectively. Using principal component analysis, the three major asteroid complexes and a class, S-, C-, and X-complexes and V class are found to be well separated in the principal component plane (spectral slope and 1 micron absorption depth) with both filter systems. We will present and discuss the results of our newly proposed three-dimensional color taxonomy for asteroids using the whole dataset (Roh et al., to be submitted).

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The Zodiacal Light Observations with the MIRIS

  • Pyo, Jeong-Hyun;Jeong, Woong-Seob;Matsumoto, Toshio;Lee, Dae-Hee;Han, Won-Yong;Ree, Chang-Hee;Park, Young-Sik;Nam, Uk-Won;Moon, Bong-Kon;Park, Sung-Joon;Cha, Sang-Mok;Lee, Sung-Ho;Yuk, In-Soo;Park, Jang-Hyun;Jin, Ho;Lee, Duk-Hang;Lee, Hyung-Mok;Hong, Seung-Soo
    • The Bulletin of The Korean Astronomical Society
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    • v.36 no.1
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    • pp.42.1-42.1
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    • 2011
  • The main payload of the Science and Technology Satellite 3 (STSAT-3), Multipurpose Infrared Imaging System (MIRIS), will be equipped with the wide-field near-infrared camera. Its wide field-of-view (3.67×3.67) is optimal for the observation of the zodiacal light (ZL), the sunlight scattered by the interplanetary dust (IPD). The MIRIS will continuously monitor the seasonal variation of the ZL towards both north and south ecliptic poles, which is caused by the asymmetries of the IPD distribution with respect to the Sun and the ecliptic plane. In addition to the monitoring observations, we are planning pointed observations for compelling structures in the ZL, the asteroidal dust bands and the gegenschein. This presentation proposes the zodiacal light observations with the MIRIS and discusses the expected results.

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Comparison and Application Quantitative Indices for Analyzing Total Green Space in an Urban Area - Guro-gu in Seoul - (도시 공원녹지의 총량 산정을 위한 지표 비교 및 적용 - 서울시 구로구를 사례로 -)

  • Lee, Kyong-Jae;Choi, Jin-Woo;Han, Bong-Ho
    • Journal of the Korean Institute of Landscape Architecture
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    • v.36 no.4
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    • pp.27-35
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    • 2008
  • The purpose of this study was to compare and apply quantitative indices for analyzing the total green space in an urban area, targeting Guro-Gu, Seoul. The indices were classified in terms of plane, solid and urban planning. The park area per person as an index of the park green's total volume was 2.34m2. This clearly shows the deficiency of park area. However, it did not reflect actual green space, since undesignated forests, rivers and green spaces in the city were excluded. Green coverage area per person in terms of plane was 18.85m2 and was useful as an index of actual urban planting, focusing on expansion of the green space. However, the conception of total volume of park green had limitation to be recognized as a unit of area. The number of trees and green area volume per person in terms of solid was 4.1 trees and 35.8m2, respectively. This enabled reflection on qualitative improvement plans such as increasing the volume of trees for the high density of developed areas.

Functional Verification of Nylon Wire Cutting-Type Holding & Release Mechanism for 6U CubeSat's Solar Panel (나일론선 절단방식 6U 큐브위성용 태양전지판 구속분리장치의 기능검증)

  • Park, Yeon-Hyeok;Go, Ji-Seong;Chae, Bong-Geon;Lee, Seong-Ho;Oh, Hyun-Ung
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.46 no.10
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    • pp.867-875
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    • 2018
  • Conventional nylon wire cutting-type holding and release mechanisms (HRMs) are limited to securely hold the solar panel under launch environment as the size of the panel increases because the nylon wire is tightened directly on the surface of the solar panel. In this study, we proposed a nylon wire cutting-type HRM for 6U CubeSat's solar panel applying elliptic-shaped bracket with a Ball & Socket interface. The proposed HRM has the advantage of higher holding capability along in-plane and out-of plane directions of solar panel and simplicity in tightening process of nylon wire. The design drivers of structural design of CubeSat's solar panel with the proposed HRM were defined by structural analysis under launch loads. In addition, The design effectiveness of the proposed HRM was verified through the functional tests according to the thickness of nylon wire and the number of wire winding under various temperature conditions.

Comparative Analysis of Linear and Nonlinear Projection Techniques for the Best Visualization of Facial Expression Data (얼굴 표정 데이터의 최적의 가시화를 위한 선형 및 비선형 투영 기법의 비교 분석)

  • Kim, Sung-Ho
    • The Journal of the Korea Contents Association
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    • v.9 no.9
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    • pp.97-104
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    • 2009
  • This paper describes comparison and analysis of methodology which enables us in order to search the projection technique of optimum for projection in the plane. For this methodology, we applies the high-dimensional facial motion capture data respectively in linear and nonlinear projection techniques. The one core element of the methodology is to applies the high-dimensional facial expression data of frame unit in PCA where is a linear projection technique and Isomap, MDS, CCA, Sammon's Mapping and LLE where are a nonlinear projection techniques. And another is to find out the methodology which distributes in this low-dimensional space, and analyze the result last. For this goal, we calculate the distance between the high-dimensional facial expression frame data of existing. And we distribute it in two-dimensional plane space to maintain the distance relationship between the high-dimensional facial expression frame data of existing like that from the condition which applies linear and nonlinear projection techniques. When comparing the facial expression data which distribute in two-dimensional space and the data of existing, we find out the projection technique to maintain the relationship of distance between the frame data like that in condition of optimum. Finally, this paper compare linear and nonlinear projection techniques to projection high-dimensional facial expression data in low-dimensional space and analyze it. And we find out the projection technique of optimum from it.

DEVELOPMENT OF THE MECHANICAL STRUCTURE OF THE MIRIS SOC (MIRIS 우주관측카메라의 기계부 개발)

  • Moon, B.K.;Jeong, W.S.;Cha, S.M.;Ree, C.H.;Park, S.J.;Lee, D.H.;Yuk, I.S.;Park, Y.S.;Park, J.H.;Nam, U.W.;Matsumoto, Toshio;Yoshida, Seiji;Yang, S.C.;Lee, S.H.;Rhee, S.W.;Han, W.
    • Publications of The Korean Astronomical Society
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    • v.24 no.1
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    • pp.53-64
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    • 2009
  • MIRIS is the main payload of the STSAT-3 (Science and Technology Satellite 3) and the first infrared space telescope for astronomical observation in Korea. MIRIS space observation camera (SOC) covers the observation wavelength from 0.9μm to 2.0μm with a wide field of view 3.67×3.67. The PICNIC HgCdTe detector in a cold box is cooled down below 100K by a micro Stirling cooler of which cooling capacity is 220mW at 77K. MIRIS SOC adopts passive cooling technique to chill the telescope below 200 K by pointing to the deep space (3K). The cooling mechanism employs a radiator, a Winston cone baffle, a thermal shield, MLI (Multi Layer Insulation) of 30 layers, and GFRP (Glass Fiber Reinforced Plastic) pipe support in the system. Optomechanical analysis was made in order to estimate and compensate possible stresses from the thermal contraction of mounting parts at cryogenic temperatures. Finite Element Analysis (FEA) of mechanical structure was also conducted to ensure safety and stability in launching environments and in orbit. MIRIS SOC will mainly perform Galactic plane survey with narrow band filters (Pa α and Pa α continuum) and CIB (Cosmic Infrared Background) observation with wide band filters (I and H) driven by a cryogenic stepping motor.

General equations for free vibrations of thick doubly curved sandwich panels with compressible and incompressible core using higher order shear deformation theory

  • Nasihatgozar, M.;Khalili, S.M.R.;Fard, K. Malekzadeh
    • Steel and Composite Structures
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    • v.24 no.2
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    • pp.151-176
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    • 2017
  • This paper deals with general equations of motion for free vibration analysis response of thick three-layer doubly curved sandwich panels (DCSP) under simply supported boundary conditions (BCs) using higher order shear deformation theory. In this model, the face sheets are orthotropic laminated composite that follow the first order shear deformation theory (FSDT) based on Rissners-Mindlin (RM) kinematics field. The core is made of orthotropic material and its in-plane transverse displacements are modeled using the third order of the Taylor's series extension. It provides the potentiality for considering both compressible and incompressible cores. To find these equations and boundary conditions, Hamilton's principle is used. Also, the effect of trapezoidal shape factor for cross-section of curved panel element (1±z/R) is considered. The natural frequency parameters of DCSP are obtained using Galerkin Method. Convergence studies are performed with the appropriate formulas in general form for three-layer sandwich plate, cylindrical and spherical shells (both deep and shallow). The influences of core stiffness, ratio of core to face sheets thickness and radii of curvatures are investigated. Finally, for the first time, an optimum range for the core to face sheet stiffness ratio by considering the existence of in-plane stress which significantly affects the natural frequencies of DCSP are presented.

Localization of a Monocular Camera using a Feature-based Probabilistic Map (특징점 기반 확률 맵을 이용한 단일 카메라의 위치 추정방법)

  • Kim, Hyungjin;Lee, Donghwa;Oh, Taekjun;Myung, Hyun
    • Journal of Institute of Control, Robotics and Systems
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    • v.21 no.4
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    • pp.367-371
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    • 2015
  • In this paper, a novel localization method for a monocular camera is proposed by using a feature-based probabilistic map. The localization of a camera is generally estimated from 3D-to-2D correspondences between a 3D map and an image plane through the PnP algorithm. In the computer vision communities, an accurate 3D map is generated by optimization using a large number of image dataset for camera pose estimation. In robotics communities, a camera pose is estimated by probabilistic approaches with lack of feature. Thus, it needs an extra system because the camera system cannot estimate a full state of the robot pose. Therefore, we propose an accurate localization method for a monocular camera using a probabilistic approach in the case of an insufficient image dataset without any extra system. In our system, features from a probabilistic map are projected into an image plane using linear approximation. By minimizing Mahalanobis distance between the projected features from the probabilistic map and extracted features from a query image, the accurate pose of the monocular camera is estimated from an initial pose obtained by the PnP algorithm. The proposed algorithm is demonstrated through simulations in a 3D space.