• Molecules and Cells
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• v.41 no.12
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• pp.1045-1051
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• 2018

The developmentally regulated GTP binding protein 2 (DRG2) is involved in the control of cell growth and differentiation. Here, we demonstrate that DRG2 regulates microtubule dynamics in HeLa cells. Analysis of live imaging of the plus-ends of microtubules with EB1-EGFP showed that DRG2 deficiency (shDRG2) significantly reduced the growth rate of HeLa cells. Depletion of DRG2 increased 'slow and long-lived' subpopulations, but decreased 'fast and short-lived' subpopulations of microtubules. Microtubule polymerization inhibitor exhibited a reduced response in shDRG2 cells. Using immunoprecipitation, we show that DRG2 interacts with tau, which regulates microtubule polymerization. Collectively, these data demonstrate that DRG2 may aid in affecting microtubule dynamics in HeLa cells.

• The Korean Journal of Ecology
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• v.28 no.4
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• pp.181-188
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• 2005

Methods used to study carbon sequestration by soil aggregates have often excluded the concentric spatial variability and other dynamic processes that contribute to resource accessibility and solute transport within aggregates. We investigated the spatial gradients of carbon (C) and nitrogen (N) from the exterior to interior layers within macroaggregates, $6.3\sim9.5$ mm, sampled from conventional tillage (CT) and no tillage (NT) sites of a Hoytville silt clay loam. Spatial gradients in C accumulation within macroaggregates were related to the differences in C dynamics by determining the sizes and the turnover rates of fast C and slow C pools in the concentric layers of aggregates. Aggregate exteriors contained more labile C and were characterized by greater C mineralization rates than their interiors in both management systems. In contrast, C in the interior layers of aggregates was more resistant in both systems. These results indicated the spatial differentiation of C dynamics within macroaggregates, i.e., exterior layers as a reactive site and interior layers as a protective site. Greater total C distribution in the exterior layers of NT aggregates indicated more influx of C from the macropores in interaggregate space than C. mineralization (net gain of C), whereas lower C distribution within the exterior layers of CT aggregates indicated net loss of C by greater C mineralization than C influx. We found total C increased approximately 1.6-fold by the conversion of CT soils to NT management systems for a period of 36 years. Differences in total accumulation and the spatial distribution of C within aggregates affected by management were attributed to the differences in aggregate stability and pore networks controlling the spatial heterogeneities of resource availability and microbial activity within aggregates.

• Bulletin of the Korean Chemical Society
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• v.27 no.11
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• pp.1825-1831
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• 2006

The influence of solvent viscosity on conformational dynamics of the heme-pocket, a small vacant site near the binding site of myoglobin (Mb) and hemoglobin (Hb), and playing a functionally important role by serving as a station in ligand binding and escape, was studied by probing time-resolved vibrational spectra of CO photodissociated from MbCO and HbCO in $D_2O$, 75 wt% glycerol/$D_2O$, and trehalose at 283 K. Two absorption bands ($B_1$ and $B_2$) of the sample in viscous solvents, arising from CO in the heme pocket, are very similar to those in $D_2O$. Two bands in Mb and Hb under all three solvents exhibit very similar nonexponential spectral evolution ($B_1$ band; blue shifting and broadening, $B_2$ band; narrowing with a negligible shifting), suggesting that in the present experimental time window of 100 ps, the extents of the spectral shift and narrowing is much influenced neither by the viscosity of solvent nor by the quaternary contact of Hb. Spectral evolution can be described by a biexponential function with a fast universal time constant of 0.52 ps and a slow time constant ranging from 13 to 32 ps. For both proteins in all three solvents majority of spectral evolution occurs with the fast universal time constant. The magnitude of the slow rate in the spectral shift of B1 band decreases with increasing solvent viscosity, indicating that it is influenced by global conformational change which is retarded in viscous solvent, thereby serve as a reporter of global conformational change of heme proteins after deligation.

• Korean Journal of Materials Research
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• v.8 no.8
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• pp.678-684
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• 1998

By means of constant- pressure molecular dynamics simulations, we studied the liquid- glass- crystalline transition of a system composed of Lennard- Jones particles with periodic boundary conditions. Atomic volume and enthalpy were calculated as functions of temperature during heating and cooling processes. The Wendt- Abraham ratio derived from radial distribution function and the angular distribution function characterizing short range order were analyzed to distinguish between liquid, glass and crystalline states. A liquid phase resulting from a slow heating of an initial fee crystal amorphized on fast quench, but it crystallized on slow quench. When slowly heated, the amorphous phase from fast quench crystallized into an fee structure. A system with free surface was shown to melt from the surface inward at a lower temperature than bulk system and to have a strong tendency for crystallization even during a fast quench from a liquid state.

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.2
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• pp.99-106
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• 2003

A new reconfigurable model following flight control method based on direct adaptive scheme is presented. Using the timescale separation principle, both the inner-loop and the outer-loop states are controlled simultaneously. For the timescale separation assumption to be satisfied, the inner-loop model dynamics is set to be fast whereas the outer-loop model dynamics is set to be relatively slow. The stability and convergence of the proposed control law is proved by Lyapunov theorem. One of the merits of the proposed reconfigurable controller is that the FDI process and the persistent input excitation are not necessary, which is suitable for the flight control system. To evaluate the reconfiguration performance of the proposed control method, numerical simulation is performed using six degree-of-freedom nonlinear dynamics.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.1300-1303
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• 1996

In this paper a typical problem is examined that a light, general aviation airplane, such as Cessna or Navion, in gliding turn flight shows helical-dive phenomenon when pilots try to stop the descent by using elevator only. It is known from pilot's experience that in a certain flight trim it is impossible to recover from helical-dive by using elevator only. From this study it is shown that helical-dive phenomenon is involved with longitudinal/lateral dynamics coupling to airplane's aerodynamics. Also this phenomenon consists of three parts of flight dynamics; first of all, fast longitudinal motion occurs, then is followed by a little slow lateral motion, and finally logitudinal/lateral coupled motion is fully developed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.2
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• pp.289-296
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• 2015

In this paper, we propose the nonlinear control based on singular perturbation theory for position tracking and yaw regulation of planar motor. Singular perturbation theory is characterized by the existence of slow and fast transients in the system dynamics. The proposed method consists of auxiliary control to decouple error dynamics. We develop model reduction with control input. Also, we derIve decoupled error dynamics with auxiliary input. The controller is designed in order to guarantee the desired position and yaw regulation without current feedback or estimation. Simulation results validate the effect of proposed method.

• BMB Reports
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• v.38 no.1
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• pp.104-110
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• 2005

We extended the measurable time scale of DNA dynamics to microsecond using $[Ru(phen)_2(dppz)]^{2+}$ (phen = 1,10-phenanthroline, dppz = dipyrido[3,2-a:2',3'-c]phenazine) (RuPD), which displays a mean lifetime near 500 ns. To evaluate the usefulness of this luminophore (RuPD) for probing nucleic acid dynamics, its intensity and anisotropy decays when intercalated into supercoiled and linear pBluescript (pBS) II SK(+) phagemids were examined using frequency-domain fluorometry with a blue light-emitting diode (LED) as the modulated light source. The mean lifetime for the supercoiled phagemids (< $\tau$ > = 489.7 ns) was somewhat shorter than that for the linear phagemids (< $\tau$ > = 506.4 ns), suggesting a more efficient shielding from water by the linear phagemids. The anisotropy decay data also showed somewhat shorter slow rotational correlation times for supercoiled phagemids (997.2 ns) than for the linear phagemids (1175.6 ns). The slow and fast rotational correlation times appear to be consistent with the bending and torsional motions of the phagemids, respectively. These results indicate that RuPD can have applications in studies of both bending and torsional dynamics of nucleic acids.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.2
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• pp.90.2-90.2
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• 2013

Filament eruptions are one of the energetic phenomena on the solar surface with flares and coronal mass ejections (CMEs). We observed the whole process of filament eruption that occurred in AR 11305 in association with a C5.6 flare on 2011 September 29th using the Fast Imaging Solar Spectrograph (FISS) and the Solar Dynamics Observatory (SDO). The eruption consists of a slow phase with a transverse speed of ~10 km $s^{-1}$ in 16 minutes and a fast phase with a transverse speed of ~200 km $s^{-1}$ in 3 minutes. Near the beginning of slow phase eruption, preflare brightening occurred beneath the filament in $H{\alpha}$ and some EUV images. The preflare brightening region is associated with a blue-shifted $H{\alpha}$ feature with a speed of ~60 km $s^{-1}$. It appears that this is the outflow from magnetic reconnection which may have occurred at relatively low atmosphere. Our result support the notion that the preflare brightening is a process of magnetic reconnection playing an important role in triggering the filament eruption by deformative the magnetic field lines under the eruptive filament.

• Proceedings of the Korea Society for Simulation Conference
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• 2001.10a
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• pp.37-43
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• 2001

New product development has been a key element fur organizational evolution. The bulk of research about new product strategy has focused solely on new product development function itself. This paper investigates cross-functional elements in new product development. More specifically, we suggest that there must exist a fit between new product strategy and value chain strategy. It means that, in order to support new product development activity, there must exist a relevant value chain strategy. We consider three types of integration - internal integration, customer integration, and supplier integration - as strategic elements of value chain strategy. For the case of new product strategy, we consider market newness and product technology unfamiliarity as strategic elements. We also consider two types of learning characteristic, i.e., \\\"fast-adaptive learning\\\" and \\\"slow-adaptive leaning\\\" as control factor. Learning characteristic represents firms organizational capability related with organizational learning. For example, fur fast-adaptive learning case, the effect of integration appears early in time. System dynamics simulation is employed to verify our research framework. The results exhibit that there must exist cross-functional relationships between value chain strategy and new product strategy in order to shorten total development time.al development time.