• Title/Summary/Keyword: Kinematics Features

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STaRS Gen 2: Sejong Radiative Transfer through Raman and Rayleigh Scattering in Dusty Medium

  • Chang, Seok-Jun;Lee, Hee-Won;Seon, Kwang-Il
    • The Bulletin of The Korean Astronomical Society
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    • v.46 no.2
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    • pp.81.2-81.2
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    • 2021
  • Emission features formed through Raman scattering with atomic hydrogen provide unique and crucial information to probe the distribution and kinematics of a thick neutral region illuminated by a strong far-ultraviolet radiation source. We introduce a new 3-dimensional Monte-Carlo code to describe the radiative transfer of line photons subject to Raman and Rayleigh scattering with atomic hydrogen. In our Sejong Radiative Transfer through Raman and Rayleigh Scattering (STaRS) code, the position, direction, wavelength, and polarization of each photon is traced until escape. The thick neutral scattering region is divided into multiple cells. Each cell is characterized by its velocity and density, which ensures flexibility of the code in analyzing Raman-scattered features formed in a neutral region with complicated kinematics and density distribution. We are continuously developing STaRS to adopt the absorption and scattering effect by dust. This presentation introduces STaRS and its current state and study.

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Inverse Kinematics of a Serial Manipulator : Redundancy and a Closed-rom Solution by Exploting Geomertiric Constraints (원료불출기의 역기구학 : 여유자유도와 구속조건을 이용한 닫힌 형태의 해)

  • 홍금식;김영민;최진태;신기태;염영일
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1996.04a
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    • pp.661-665
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    • 1996
  • An inverse kinemetics problem of a reclaimer which digs and transports ironstones or coals in the raw yard is investigated. Because of the special features of the reclaimer of which scooping buckets are attached around the rotating drum at the end of boom, kinematic redundancy occurs in determining the joint varialbes For a given reclaiming point in space the forward kinematics yields 3 equations, however the number of involved variables in the equations are four. A plane equation approximating the surface near a reclaiming point is obtained by considering 8 adjacent points surrounding the reclaiming point. One extra equation to overcome redunduncyis further obtained from the condition that the normal vector at a reclaiming point is perpendicular to the plane. An approximate solution for a simplified problem is first discussed, Numerical solution for the oritinal nonlinear porblem with a constraint equation is also investigated. Finally a closed form solution which is not exact but sufficiently close enough is proposed by exploiting geometric constraint.

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Kinematics Analysis of a 5-Axis Ultrasonic Inspection Equipment (5축 초음파 검사장비의 기구학 해석)

  • Han, Myung-Chul;Sung, Chang-Min
    • Journal of the Korean Society for Precision Engineering
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    • v.32 no.1
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    • pp.89-96
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    • 2015
  • In this paper, it is studied that kinematic analysis of a 5-axis ultrasonic inspection equipment. The equipment is comprised of three straight axes and two rotary axes. With features of ultrasonic, the transmitter and receiver of the equipment are vertical to a test surface, operating at regular intervals. To perform this well, the motions of every link should be found on the based of kinematic analysis of the equipment. We chose starting point for testing and defined relations among all links through transformation of coordinates. For double curvature-shaped test object, we generated test paths. To follow these, we found motions of all links using inverse kinematics. By using Matlab/Simulink, simulator was developed, so that we could find out desired trajectories of main axes for a scan.

Target Classification for Multi-Function Radar Using Kinematics Features (운동학적 특징을 이용한 다기능 레이다 표적 분류)

  • Song, Junho;Yang, Eunjung
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.26 no.4
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    • pp.404-413
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    • 2015
  • The target classification for ballistic target(BT) is one of the most critical issues of ballistic defence mode(BDM) in multi-function radar(MFR). Radar responds to the target according to the result of classifying BT and air breathing target(ABT) on BDM. Since the efficiency and accuracy of the classification is closely related to the capacity of the response to the ballistic missile offense, effective and accurate classification scheme is necessary. Generally, JEM(Jet Engine Modulation), HRR(High Range Resolution) and ISAR(Inverse Synthetic Array Radar) image are used for a target classification, which require specific radar waveform, data base and algorithms. In this paper, the classification method that is applicable to a MFR system in a real environment without specific waveform is proposed. The proposed classifier adopts kinematic data as a feature vector to save radar resources at the radar time and hardware point of view and is implemented by fuzzy logic of which simple implementation makes it possible to apply to the real environment. The performance of the proposed method is verified through measured data of the aircraft and simulated data of the ballistic missile.

An Implementation of Real-time Motion Restoration System based on Inverse Kinematics (역운동학을 이용한 실시간 동작 복원 시스템 구현)

  • Lee, R.H.;Lee, C.W.
    • Journal of Korea Multimedia Society
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    • v.17 no.6
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    • pp.741-750
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    • 2014
  • This paper presents a real-time motion restoration system for people who need remedial exercise of musculoskeletal based on Inverse Kinematics. A new approach is suggested to recognize a gesture based on restored human motion which is calculated the 3D positions of intermediate joints using 3D positions of body features estimated from images. For generating the 3D candidate positions of intermediate joints which cannot be extracted from images, we apply an Inverse Kinematics theory to compute the target position of intermediate joints. And we can reduce the number of candidate positions by applying the various physical constraints of body. Finally, we can generate the more accurate final position using the Kalman filter for a motion tracking and the relationship between the previous frame information and the candidate positions. The system provide motion information which are rotation angle and height in real-time, therefore the rehabilitation exercises can be performed based on the information and figured out proper exercise for individual status.

STARS: A 3D GRID-BASED MONTE CARLO CODE FOR RADIATIVE TRANSFER THROUGH RAMAN AND RAYLEIGH SCATTERING WITH ATOMIC HYDROGEN

  • Chang, Seok-Jun;Lee, Hee-Won
    • Journal of The Korean Astronomical Society
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    • v.53 no.6
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    • pp.169-179
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    • 2020
  • Emission features formed through Raman scattering with atomic hydrogen provide unique and crucial information to probe the distribution and kinematics of a thick neutral region illuminated by a strong far-ultraviolet radiation source. We introduce a new 3-dimensional Monte-Carlo code in order to describe the radiative transfer of line photons that are subject to Raman and Rayleigh scattering with atomic hydrogen. In our Sejong Radiative Transfer through Raman and Rayleigh Scattering (STaRS) code, the position, direction, wavelength, and polarization of each photon is traced until escape. The thick neutral scattering region is divided into multiple cells with each cell being characterized by its velocity and density, which ensures flexibility of the code in analyzing Raman-scattered features formed in a neutral region with complicated kinematics and density distribution. To test the code, we revisit the formation of Balmer wings through Raman scattering of the far-UV continuum near Lyβ and Lyγ in a static neutral region. An additional check is made to investigate Raman scattering of O vi in an expanding neutral medium. We find a good agreement of our results with previous works, demonstrating the capability of dealing with radiative transfer modeling that can be applied to spectropolarimetric imaging observations of various objects including symbiotic stars, young planetary nebulae, and active galactic nuclei.

Internal structure and kinematics of the massive star forming region W4

  • Lim, Beomdu;Yun, Hyeong-Sik;Rauw, Gregor;Naze, Yael;Kim, Jinyoung S.;Lee, Jeong-Eun;Hwang, Narae;Park, Byeong-Gon;Park, Sunkyung;Sung, Hwankyung;Kim, Seulgi
    • The Bulletin of The Korean Astronomical Society
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    • v.44 no.2
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    • pp.72.3-72.3
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    • 2019
  • OB associations are young stellar systems on a few tens to a hundred parsec scale, and many of them are composed of multiple substructures. It is suggested that some hints about their formation process are probably imprinted on structural features and internal kinematics. In this context, we study the massive star forming region W4 in the Cassiopeia OB6 association using the Gaia proper motion data and high-resolution optical spectra taken from Hectochelle on MMT. We probe the structure and internal kinematics of W4 to trance its formation process. Several nonmembers with different kinematic properties are excluded in our sample. Some of them may be young stellar population spread over a large area of the Perseus spiral arm given their wide spatial distribution over 50 parsecs. W4 is composed of an central open cluster (IC 1805) and an extended stellar component. Their global expansion patterns are detected in stellar proper motion. In this presentation, we will further discuss the formation process of W4, based on the velocity dispersions of stars comprising these substructure.

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On the Use of Finite Rotation Angles for Spacecraft Attitude Control

  • Kim, Chang Joo;Hur, Sung Wook;Ko, Joon Soo
    • International Journal of Aeronautical and Space Sciences
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    • v.18 no.2
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    • pp.300-314
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    • 2017
  • This paper examines finite rotation angle (FRA) applications for spacecraft attitude control. The coordinate transformation matrix and the attitude kinematics represented by FRAs are introduced. The interpolation techniques for the angular orientations are thoroughly investigated using the FRAs and the results are compared to those using traditional methods. The paper proposes trajectory description techniques by using extremely smooth polynomial functions of time, which can describe point-to-point attitude maneuvers in a realizable and accurate manner with the help of unique FRA features. In addition, new controller design techniques using the FRAs are developed by combining the proposed interpolation techniques with a model predictive control framework. The proposed techniques are validated through their attitude control applications for an aggressive point-to-point maneuver. Conclusively, the FRAs provide much more flexibility than quaternions and Euler angles when describing kinematics, generating trajectories, and designing attitude controllers for spacecraft.

Spectroscopy of Globular Clusters in the Core of the Virgo Cluster

  • Ko, Youkyung;Hwang, Ho Seong;Lee, Myung Gyoon;Sohn, Jubee;Lim, Sungsoon;Park, Hong Soo
    • The Bulletin of The Korean Astronomical Society
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    • v.39 no.2
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    • pp.51.1-51.1
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    • 2014
  • The Virgo cluster, the nearest galaxy cluster, is dynamically young, hosting numerous globular clusters in galaxies as well as intracluster globular clusters (IGCs). We obtained spectra of globular cluster candidates in the core region of the Virgo cluster using Hectospec at MMT to study the kinematics of the globular clusters. The targets are located at a large range (50 kpc < d < 500 kpc) from M87, the most massive galaxy in Virgo. We distinguish the genuine globular cluster population in the targets by inspecting their spectral features and radial velocities. As a result, a significant number of IGCs are found. We present preliminary results of the kinematics of globular clusters in the Virgo core region.

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Automated Assembly Modeling using Kinematics Constraints (기구학적 구속조건을 이용한 자동 조립 모델링)

  • Kim Jae Seong;Kim Gwang Su
    • Proceedings of the Korean Operations and Management Science Society Conference
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    • 2002.05a
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    • pp.272-279
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    • 2002
  • A common task in assembly modeling is the determination of the position and orientation of a set of components by solving the spatial relationships between them. Assembly models could be constructed at various levels of abstraction. They could be classified into component or geometry-level assembly models. The geometry-level assembly design approach using mating constraints such as against and fits is widely used in the commercial modelers, but it may be very tedious in some cases fur designer. In this paper, we propose a new method to construct an assembly model at the component-level by extracting joint mating features from the kinematics constraints specified between components. The assembly model constructed using the proposed method includes hierarchical and relational assembly models, component/sub-assembly positions and degrees of freedom information. The proposed method is more intuitive and natural way of assembly design and it guarantees the topological robustness of assembly modification such as component replacement and modification.

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