• Title/Summary/Keyword: Dimensional Variations

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VIMAP: AN INTERACTIVE PROGRAM PROVIDING RADIO SPECTRAL INDEX MAPS OF ACTIVE GALACTIC NUCLEI

  • Kim, Jae-Young;Trippe, Sascha
    • Journal of The Korean Astronomical Society
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    • v.47 no.5
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    • pp.195-199
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    • 2014
  • We present a GUI-based interactive Python program, VIMAP, which generates radio spectral index maps of active galactic nuclei (AGN) from Very Long Baseline Interferometry (VLBI) maps obtained at different frequencies. VIMAP is a handy tool for the spectral analysis of synchrotron emission from AGN jets, specifically of spectral index distributions, turn-over frequencies, and core-shifts. In general, the required accurate image alignment is difficult to achieve because of a loss of absolute spatial coordinate information during VLBI data reduction (self-calibration) and/or intrinsic variations of source structure as function of frequency. These issues are overcome by VIMAP which in turn is based on the two-dimensional cross-correlation algorithm of Croke & Gabuzda (2008). In this paper, we briefly review the problem of aligning VLBI AGN maps, describe the workflow of VIMAP, and present an analysis of archival VLBI maps of the active nucleus 3C 120.

Landsat Images Applied for Analyzing Spatial Flow and Water Quality Patterns in a Korea Estuary Dam

  • Park, S.W.;Torii, K.;Aoyama, S.;Cho, B. J.
    • Proceedings of the KSRS Conference
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    • 2003.11a
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    • pp.1239-1241
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    • 2003
  • This paper presents the results of Landsat-TM imagery applications for detecting spatial variations of the water environments in the Saemankeum (STLR) project areas. The simulated tidal flow patterns from a two -dimensional hydro - dynamic model and water quality data from STRL project were used for relationships with the satellite data. Unsupervised classification of the tidal water body reflects the overall flow patterns at a flooding tide. Regressive equations for water quality parameters were derived and used for supervised classifications. The results were found to be useful to synoptically evaluate the water environments during the construction stages of the STLR project.

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Effect of Strain Slates on the Formation of Shear Textures during Rolling in fcc Metals (FCC 금속에서 압연 전단집합조직의 형성에 미치는 변형상태의 효과)

  • Kang C. K.;Choi W. G.;Huh M. Y.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2005.05a
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    • pp.483-486
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    • 2005
  • In order to study the effect of strain states on the formation of shear textures during rolling in fcc metals, the evolution of textures was simulated by the full constrain model using various ideal strain states. Considering rolling as a two-dimensional problem, i.e., $\varepsilon_{22}\;=\;\varepsilon_{12}\;=\;\varepsilon_{23}\;=\;0$, the deviation from the plane-strain state manifest itself as nonzero contribution of $\varepsilon_{13}$. With increasing variations of $\varepsilon_{13}$, shear textures develop. The sign of ell hardly affects the evolution of textures. The texture simulation with various idealized strain states indicates that the ratio $\mid\varepsilon_{13}\mid/\mid\varepsilon_{11}\mid$ in each time interval in a roll gap plays a dominant role in the evolution of textures during rolling.

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A Study on PTV analysis of AC Electroosmotic Flows in the Microchannel with Coplanar electrodes (마이크로 채널 내 교류 전기 삼투 유동에 대한 PTV해석)

  • Heo, Hyeung-Seok;Kang, Sang-Mo;Suh, Yong-Kweon
    • 한국가시화정보학회:학술대회논문집
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    • 2006.12a
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    • pp.113-116
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    • 2006
  • AC-electroosmosis is one of the electrokinetic forces leading to phenomena peculiar in the microfluidics. This paper shows particle deformation in the microchannel with rectangular electrodes on the bottom wall for the AC-electroosmotic flows. We make a PDMS microchannnel with ITO electrodes To measure velocity distributions of the particles we used a three-dimensional particle tracking velocimetry (micro-PTV) technique this method is Particle tracking by interpolation the diffraction pattern ring diameter variations with the defocusing distances of base particle locations. we induce a function of frequency at the electrode. We find the velocity of particles is the most at the edge of the electrodes and Particles move to side wall or center of the channel for the bottom and middle.

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Analysis of Traumatic Brain Injury Using a Finite Element Model

  • Suh Chang-Min;Kim Sung-Ho;Oh Sang-Yeob
    • Journal of Mechanical Science and Technology
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    • v.19 no.7
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    • pp.1424-1431
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    • 2005
  • In this study, head injury by impact force was evaluated by numerical analysis with 3-dimensional finite element (FE) model. Brain deformation by frontal head impact was analyzed to evaluate traumatic brain injury (TBI). The variations of head acceleration and intra-cranial pressure (ICP) during the impact were analyzed. Relative displacement between the skull and the brain due to head impact was investigated from this simulation. In addition, pathological severity was evaluated according to head injury criterion (HIC) from simulation with FE model. The analytic result of brain damage was accorded with that of the cadaver test performed by Nahum et al.(1977) and many medical reports. The main emphasis of this study is that our FE model was valid to simulate the traumatic brain injury by head impact and the variation of the HIC value was evaluated according to various impact conditions using the FE model.

Numerical Study on the Variation of Axial Thrust of Rotating Disc with Pump-Out Vane (POV가 부착된 회전 원판의 축추력 변화에 관한 연구)

  • Seong Seong-Mo;Kang Shin-Hyoung
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.30 no.3 s.246
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    • pp.230-237
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    • 2006
  • Flows in the cavity with pump out vane are calculated using the CFX-Tascflow CFD code. flow calculations are performed for different values of vane height, numbers, leakage flow rate, and rotational speed. The flow is very complex and three dimensional with strong vortex and leakage flow over the vane. The variations of pressure coefficient and K-factor with these parameters and resulting effects on the thrust and torque are studied. The present study contributes to showing the capability of flow simulation of back cavity with pump-out vane. The calculated results are good enough to be used back cavity design.

Numerical study of bonded composite patch repair in damaged laminate composites

  • Azzeddine, Nacira;Benkheira, Ameur;Fekih, Sidi Mohamed;Belhouari, Mohamed
    • Advances in aircraft and spacecraft science
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    • v.7 no.2
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    • pp.151-168
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    • 2020
  • The present study deals with the repair of composite structures by bonding composite patches. The composite structure is a carbon/epoxy laminate with stacking sequence [45/-45/0/90]S. The damaged zone is simulated by a central crack and repaired by bonding symmetrical composite patches. The repair is carried out using composite patches laminated from the same elemental folds as those of the cracked specimen. Three-dimensional finite element method is used to determine the energy release rate along the front of repaired crack. The effects of the repair technique used single or double patch, the stacking sequence of the cracked composite patch and the adhesive properties were highlighted on the variations of the fracture energy in mode I and mixed mode I + II loading.

A Field Tracer Experiment by using RI and Numerical Modelling in River (RI를 이용한 하천 현장실험 및 수치 모델링)

  • Kim, Ki Chul;Chun, Il Young;Jung, Sung Hee;Lee, Jung Lyul;Suh, Kyung Suk
    • Journal of Radiation Industry
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    • v.2 no.3
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    • pp.135-140
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    • 2008
  • A field tracer experiment using radioisotope was carried out to investigate the characteristics of a pollutant transport and a determination of the dispersion coefficients in a river system. The dispersion coefficients in the longitudinal and transverse directions were determined by using the measured concentration of a radioisotope. The two-dimensional numerical models were applied to calculate the flow and concentration fields at the experimental site. Several numerical simulations were performed to investigate the effects of the numerical results according to variations of the dispersion coefficients. The calculated concentrations agreed well with the measured ones.

A unified method for stresses in FGM sphere with exponentially-varying properties

  • Celebi, Kerimcan;Yarimpabuc, Durmus;Keles, Ibrahim
    • Structural Engineering and Mechanics
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    • v.57 no.5
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    • pp.823-835
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    • 2016
  • Using the Complementary Functions Method (CFM), a general solution for the one-dimensional steady-state thermal and mechanical stresses in a hollow thick sphere made of functionally graded material (FGM) is presented. The mechanical properties are assumed to obey the exponential variations in the radial direction, and the Poisson's ratio is assumed to be constant, with general thermal and mechanical boundary conditions on the inside and outside surfaces of the sphere. In the present paper, a semi-analytical iterative technique, one of the most efficient unified method, is employed to solve the heat conduction equation and the Navier equation. For different values of inhomogeneity constant, distributions of radial displacement, radial stress, circumferential stress, and effective stress, as a function of radial direction, are obtained. Various material models from the literature are used and corresponding temperature distributions and stress distributions are computed. Verification of the proposed method is done using benchmark solutions available in the literature for some special cases and virtually exact results are obtained.

Effect of a Solid Insert on Thermal Stratification in a Side-Heated Natural Convection Enclosure (측면가열 자연대류 밀폐공간에서 고체 삽입물이 열성층화에 미치는 영향)

  • 김수현
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.16 no.3
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    • pp.211-217
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    • 2004
  • Effect of a solid insert on thermal stratification in the natural convection enclosure is numerically investigated. The enclosure consists of two differently heated vertical walls and two adiabatic horizontal walls. A solid insert is located in the middle of the enclosure. The non-dimensional governing equations are solved by using the SIMPLER algorithm. The computations are carried out with the variations of thermal conductivity, width and height of the solid insert. The Prandtl number of the fluid in an enclosure is fixed at Pr=0.71, Two cases of Rayleigh number are considered in the present study, i.e., Ra:10$^3$ and 10$^{6}$ . The thermal stratification attenuates as thermal conductivity, width, and height of the solid insert are increased. As the thermal conductivity ratio of a solid insert to fluid increases beyond (equation omitted)10$^3$, the thermal stratification ratio shows an asymptotic value.