• Journal of Advanced Research in Ocean Engineering
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• v.4 no.1
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• pp.35-46
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• 2018

In this paper, safety analysis of the process of installing offshore structures such as manifolds and jacket-type substructures using floating cranes and barges in waves is performed. The safety analysis consists of three components. First, the dynamic responses of the offshore structure, cranes, and barge, all of which are moored and connected using wire ropes, are analyzed. Second, tensions in the wire ropes connecting the cranes and the offshore structures are calculated. Finally, any collision between the offshore structure and the cranes or the barge that transports the offshore structure is detected. Equations of motion of the offshore structure, cranes, and barge are formulated based on multibody dynamics, as well as considering the hydrostatic, hydrodynamic, and mooring forces. Additionally, proportional-derivative control of the tagline between the cranes and the offshore structure is performed to verify the safety of the installation process, as well as for reducing the dynamic response and collisions among them.

• Bulletin of the Korean Chemical Society
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• v.35 no.3
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• pp.851-857
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• 2014

Carotenoids, natural antenna pigments in photosynthesis share a symmetric backbone of conjugated polyenes. Contrary to the symmetric and almost planar geometries of carotenoids, excited state structure and dynamics of carotenoids are exceedingly complex. In this paper, recent infrared and visible transient absorption measurements and excitation dependent dynamics of 8'-apo-${\beta}$-caroten-8'-al and 7',7'-dicyano-7'-apo-${\beta}$-carotene will be reviewed. The recent visible transient absorption measurements of 8'-apo-${\beta}$-caroten-8'-al in polar and nonpolar solvents will also be introduced to emphasize the complex excited-state dynamics and unsolved problems in the $S_2$ and $S_1$ excited states.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.8
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• pp.826-832
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• 2007

Fully flexible cell preserves Hamiltonian in structure so that the symplectic time integrator is applicable to the equations of motion. In the direct formulation of fully flexible cell N-Sigma-T ensemble, a generalized leapfrog time integration (GLF) is applicable for fully flexible cell simulation, but the equations of motion by GLF has structure of implicit algorithm. In this paper, the time integration formula is derived for the fully flexible cell molecular dynamics simulation by using the splitting time integration. It separates flexible cell Hamiltonian into terms corresponding to each of Hamiltonian term. Thus the simple and completely explicit recursion formula was obtained. We compare the performance and the result of present splitting time integration with those of the implicit generalized leapfrog time integration.

• Korean System Dynamics Review
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• v.10 no.2
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• pp.103-120
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• 2009

Using various data derived from the regional innovation projects in the IT and BT-sectors within Chungbuk Province, this study tries to observe formation processes of network connecting structure and their spill-over effects. Considering the dynamic nature of key issues, it applies both social network analysis and causal loop methods. After a series of simulation exercises, we find that so-called extroverted regional innovation projects, that is, ones financially supported by the central government, reveal a higher tendency in the centrality, heavily depending on a handful of well reputed organizations. It is quite similar to the reinforcing mechanism, resulting in the rich-get-richer and the poor-get-poorer. Compared with the existing documents, nonetheless, it shows relatively weak in the mechanism strength, implying the fact that regional innovation projects have significantly contributed to ameliorating the unequal distribution of innovation organizations within Chungbuk Province. On the other hand, this study concludes that all the brokerage organizations related to the regional innovation projects have settled in Chungbuk Province. Whereas the Capital Region-based organizations present a higher tendency in the knowledge-network, it seems that the regional innovation projects have significantly contributed to upgrading direct and indirect competitiveness of the local organizations.

• Journal of Korean Port Research
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• v.12 no.1
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• pp.1-8
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• 1998

If a system has a large boundary and complexity, forecast's accuracy will be very low when consider the system's substance as black box. Thus, it is necessary that analysis by structure model. To examine competition in Northeast Asia Ports, it has assumed that the form of structure model, For which the System Dynamics method is adapted in this paper. Northeast Asia Ports Model includes five ports - Pusan, Kobe, Yokohama, Kaoshiung, Keelung, - which are adjacent to each other by geographically and has a competition relation. The Northeast Asia Ports Model has several sub-systems which consists of each unit port models. And, each unit port model found by quantitive, qualititive factors and their feedback loops. All effects which components of one port have influence to components of the rest ports must be surveyed in order to construct Northeast Asia Ports Model, but it may be impossible currently. In this paper Northeast Asia Ports Model was simplified by HFP-Hierarchical Fuzzy Process Method-adapted to integration of level variables of unit port model. Container cargo volumes in Northeast Ports Model is distributed by results of HFP method. And distributed container cargo volumes effected to unit port model. Developed model can estimate change of container cargo volumes in competitive relation by alternation of simple parameter, and reflects dynamics characteristics which are included in model.

• Korean System Dynamics Review
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• v.2 no.2
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• pp.97-118
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• 2001

To solve the policy problem between transportation and environment in trade-offs, above all, it is necessary to understand the complicated relationship between transportation and environment clearly before selecting policy alternatives. From this point of view, this study will propose the logic structure to examine the complex interaction of transportation and environment and investigate theoretically what kinds of impact would appear by the air related polices. In this research, we used ’system-dynamics’ which investigates the complexity through the flow of information and materials and the interaction of elements, which constitutes systems. System Dynamics is an approach that the variables to decide structural relationship in a system affect one another not in only-way but in inter-way and the power of influence changes time by time. This research is trying to examine the complex interaction of transportation and air pollution. For achieving this purpose, causal maps in System Dynamics approach were used. The main issues are as follows; first, to investigate the dynamic relationship between transportation and air pollution caused by exhaust emission gas. Second, to structuralize the logic of simulation to experiment the impacts of policies to relieve air pollution.

• Journal of the Korean Society for Precision Engineering
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• v.10 no.4
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• pp.94-103
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• 1993

In this work, the imaginary part of the inner modulation transfer function of the cutting dynamics is introduced for tool wear monitoring. Time-series method is utilized to construct the general three dimensional cutting dynamics whose imaginary part of the inner modulation transfer funcition shows the proportionality to tool wear at the natural frequency of the machine tool dynamics. Thus model is reduced to single-input single-output model without altering the proportionality characteristics to tool wear and implemented to the dual computer system in which one computer performs measurement while the other calculates the imaginary part of the inner modulation transfer function of the cutting dynamics by the batch least square method. The values of the imaginary part at the natural requency of the machine tool structure in the cutting direction are compared to the one calculated during machining with a brand new tool to decide the current status of the tool. The experiments shows the relevance of the proposed concept.

• Bulletin of the Korean Chemical Society
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• v.20 no.3
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• pp.285-290
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• 1999

In the present paper, we report a molecular dynamics (MD) simulation study for the structure and dynamics of H+ ions in non-rigid dehydrated H12-A zeolite framework at 298.15 K, using the same method we used in our previous studies of rigid and non-rigid zeolite-A frameworks. It is found that two different structures appear, depending on the choice of the Lennard-Jones parameter (σ) for the H+ ion, as is also observed in the study of rigid dehydrated H12-A zeolite framework, but the ranges of σ are different for the two structures. It is also found that some of the H+ ions exchanged their sites without changing the number of H+ ions at each site. The agreement between experimental and calculated structural parameters for non-rigid dehydrated H12-A zeolite is generally quite good. The calculated IR spectrum by Fourier transform of the total dipole moment auto-correlation function shows two major peaks, one around 2700 cm-1 and the other around 7000 cm-1. The former appears in the calculated IR spectra of non-rigid zeolite-A framework only system and the latter remains unexplained except, perhaps, as an indication of a new formation of a vibrational mode of the framework due to the adsorption of the H+ ions.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.8
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• pp.764-772
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• 2009

In this study, fluid/structure coupled analyses have been conducted for 3-D stator and rotor configuration. Advanced computational analysis system based on computational fluid dynamics(CFD) and computational structural dynamics(CSD) has been developed in order to investigate fluid/structure responses of general stator-rotor configurations. To solve the fluid/structure coupled problems, fluid domains are modeled using the structural grid system with dynamic moving and local deforming techniques. Reynolds-averaged Navier-Stokes equations with Spalart-Allmaras(S-A) and SST ${\kappa}-{\omega}$ turbulence models are solved for unsteady flow problems. A fully implicit time marching scheme based on the Newmark direct integration method is used for computing the coupled aeroelastic governing equations of the 3-D turbine blades for fluid-structure interaction(FSI) problems. Detailed fluid/structure analysis responses for stator-rotor interaction flow conditions are presented to show the physical performance and flow characteristics.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.563-569
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• 2008

In this study, fluid/structure coupled analyses have been conducted f3r 3-D stator and rotor configuration. Advanced computational analysis system based on computational fluid dynamics (CFD) and computational structural dynamics (CSD) has been developed in order to investigate fluid/structure responses of general stator-rotor configurations. To solve the fluid/structure coupled problems, fluid domains are modeled using the structural grid system with dynamic moving and local deforming techniques. Reynolds-averaged Navier-Stokes equations with Spalart-Allmaras (S-A) and SST ${\kappa}-{\omega}$ turbulence models are solved for unsteady flow problems. A fully implicit time marching scheme based on the Newmark direct integration method is used for computing the coupled aeroelastic governing equations of the 3-D turbine blades for fluid-structure interaction (FSI) problems. Detailed fluid/structure analysis responses for stator-rotor interaction flow conditions are presented to show the physical performance and flow characteristics.