• Title/Summary/Keyword: temporal variations

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Temperature Variations in the Mixed Layer with the Passage of Typhoons Using One-Dimensional Numerical Model (1차원 모델상에서 태풍통과시의 혼합층 수온 변화)

  • Hong, Chul-Hoon;Masuda, Akira
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.51 no.1
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    • pp.107-112
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    • 2018
  • One-dimensional numerical model is implemented to investigate temperature variations in the mixed layer depth (MLD) with the passage of typhoons. In the model, we assume a non-divergent, infinite ocean and consider wind effects only, excluding isostatic effects (inverse barometric effects) and upwelling with vertical movement of the water column. Numerical experiments investigate the effects of typhoon tracks on temperature variations, including their dependence on vertical resolutions in the MLD and these results are compared with those in a three-dimensional primitive equation model (POM). The model reproduces features of the observed temperature variations in the MLD fairly well, and implies that wind effects, rather than isostatic effects, play a predominant role in temporal and spatial temperature variations in the MLD. After the passage of typhoons, however, the model does not reproduce well the temperature variations observed in the MLD, because a limitation of the model is its inability to reproduce events such as cyclonic eddy formation (Hong et al., 2011; Masuda and Hong, 2011). The model also shows well the so called 'rightward bias' (Price, 1981) of sea surface cooling which is the most predominant in the right hand side of typhoon's track.

Study on the Turbulent Edge Propagation Speed of a Lifted Diffusion Flame in Turbulent Mixing Layer (난류 혼합층 확산화염에서 부상선단의 난류전파속도에 대한 연구)

  • Kim, Jun-Hong;Chung, S.H.;Ahn, K.Y.;Kim, J.S.
    • 한국연소학회:학술대회논문집
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    • 2004.11a
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    • pp.55-61
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    • 2004
  • Leading front of a lifted diffusion flame in turbulent mixing layer was investigated in order to find a appropriate definition of the turbulent edge propagation speed. The turbulent lifted diffusion flame was simulated by employing the flame hole dynamics combined with level-set method which yields a temporally evolving turbulent extinction process. By tracing the leading front locations of the temporal flame edges, temporal variations of the liftoff height, local flow velocity, and edge propagation speed at the leading front were investigated and they demonstrated the flame-stabilization condition of the turbulent lifted flame. Finally, a turbulent edge propagation speed was defined and its temporal variation from the simulation was discussed.

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Spatial and Temporal Distribution of Zooplankton in Gwangyang and Sachon Bay, Korea

  • Kim Saywa
    • Korean Journal of Environmental Biology
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    • v.23 no.2 s.58
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    • pp.93-97
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    • 2005
  • Zooplankton dynamics were investigated based on samples collected monthly during the period between November 1998 and October 1999 at 15 stations in Gwangyang and Sachon Bay. Zooplankters were quantitatively collected with horizontal towing through the surface and oblique hauling from the bottom to surface at each station, simultaneously. A total of 88 taxa of zooplankton were distributed and 60 taxa were identified to species. Copepods showed the prosperity in species number of 52 species. Number of taxa occurred in samples hauled obliquely always showed $2\~5$ more species than those captured in the surface except for stations near the Namhae bridge. In waters near Namhae bridge, fast current seemed to mix waters vertically. Seasonally these differences were more distinct in the spring and summer than those in other seasons possibly due to the stratification in warmer seasons. In quantitative aspects, differences between two layers seemed to be obscure. Spatial and temporal variations in species diversity of copepods showed more prosperity in pelagic realm than those in the surface. Our collection carrying out in day time might be one of the important reason to cause these differences in zooplankton dynamics between two layers.

Multiple Person Tracking based on Spatial-temporal Information by Global Graph Clustering

  • Su, Yu-ting;Zhu, Xiao-rong;Nie, Wei-Zhi
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.9 no.6
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    • pp.2217-2229
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    • 2015
  • Since the variations of illumination, the irregular changes of human shapes, and the partial occlusions, multiple person tracking is a challenging work in computer vision. In this paper, we propose a graph clustering method based on spatio-temporal information of moving objects for multiple person tracking. First, the part-based model is utilized to localize individual foreground regions in each frame. Then, we heuristically leverage the spatio-temporal constraints to generate a set of reliable tracklets. Finally, the graph shift method is applied to handle tracklet association problem and consequently generate the completed trajectory for individual object. The extensive comparison experiments demonstrate the superiority of the proposed method.

COMPARATIVE ELECTROMYOGRAPHIC ANALYSIS OF MASTICATORY MUSCLES BETWEEN BILATERAL AND UNILATERAL MASTICATORS

  • Na Sun-Hye;Kang Dong-Wan
    • The Journal of Korean Academy of Prosthodontics
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    • v.40 no.6
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    • pp.577-589
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    • 2002
  • There are several variations in normal mastication. In them, unilateral mastication is chewing, predominantly on a preferred side of the dentition and hardly on e non-preferred side. Continual unilateral mastication may alter the coordination of masticatory muscles. Although they studied about these EMG of masticatory muscles, there were no information about characteristics of masticatory muscle activity in unilateral mastication. Therefore, In this study, we investigated the activity of the masseter and anterior temporal muscles during rest, clenching in maximum intercuspation and gum chewing in habitually unilateral mastication group compared with normal group and tried to know effects of continual unilateral mastication on activity of masticatory muscles. The results of this study were as follows 1. In electromyographic activity during rest, in bilateral mastication group pattern of muscle activity of right and left side was symmetrical. But, in unilateral mastication group, records of anterior part of temporal muscle was higher than that of bilateral mastication group (p<.01) and patterns of muscle activity of right and left side in both muscle were asymmetrical.(p<.05) 2. In electromyographic activity during clenching in maximum intercuspation, records of superficial part of masseter muscle were higher than anterior part of temporal muscle in both group. Muscle activity of temporal muscle in unilateral mastication group was a little higher han bilateral mastication group and asymmetry of activity pattern in temporal and masseter muscle was shown but these differences were not statistically significant. (p<.05) 3. In electromyographic activity during gum chewing, temporal muscle was activated earlier than masseter muscle and maximum bite force is derived from masseter muscle in both group. In unilateral mastication group, electromyographic activity of masseter and temporal muscle of preferred chewing side, regardless of right or left side chewing, was higher than that of bilateral mastication group and especially, difference in masseter muscle was statistically significant. (p<.01) Based on the above results, our study suggested that recording of masticatory muscle activity will be helpful in the effective diagnosis and treatment of some types of the parafunctional habits.

Dynamics Response of a Micro Bubble under Temporal Pressure Variations (시간에 따른 압력변화에 대한 마이크로 기포의 동적 반응)

  • Lee, Woo Min;Lee, Seung Hyun;Sung, Jaeyong;Lee, Myeong Ho
    • Journal of the Korean Society of Visualization
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    • v.12 no.1
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    • pp.13-17
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    • 2014
  • The growth of micro bubble has been simulated under the variation of ambient pressure. The Rayleigh-Plesset equation governs the dynamic growth and collapse of a bubble according to pressure and temperature conditions. The Rayleigh-Plesset equation was solved by 4th-order Runge-Kutta method for wide range of pressure variations. As numerical parameters, the pressure difference between initial and final pressures, and the temporal pressure gradient are changed. The results show that the pressure difference has little effect on the growth rate of the micro bubble in the inertia controlled growth region. On the other hand, the growth rate increases linearly with the increase of the pressure gradient.