• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.5
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• pp.717-722
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• 2013

The wastewater reclamation and reusing system has been rising as an alternative of water resource exhaustion that the whole world is experiencing. In order to be able to bring about improvement of the existing wastewater reclamation and reusing system, this research has developed of Conversion-Human Machine Interaction (C-HMI) based real-time control and monitoring system such as a sensor module and gate module, web monitoring system. This system was communication almost-error-free in various environment and situation. As a result, we have achieved our goal that has to doing work correctly as a sensor and gateway module that communication error is less than 0.2% throughout the embodied system and add that it can be easily controled and configured as an interface equipment to a complex sensor of water quality. According to this, the construction of a database capable of analyzing and assessing collection, storage and various elements of reliable water quality and flow rate data can be possible.

• International Journal of Naval Architecture and Ocean Engineering
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• v.8 no.2
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• pp.188-197
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• 2016

Offshore substructures have been developed to support structures against complex offshore environments. The load at offshore substructures is dominated by waves, and deformation of waves caused by interactions with the current is an important phenomena. Wave load simulation of fixed offshore substructures in waves with the presence of uniform current was carried out by numerical wave tank technique using the commercial software, FLUENT. The continuity and Navier-Stokes equations were applied as the governing equations for incompressible fluid motion, and numerical wavemaker was employed to reproduce offshore wave environment. Convergence test against grids number was carried out to investigate grid dependency and optimized conditions for numerical wave generation were derived including investigation of the damping effect against length of the damping domain. Numerical simulation of wave and current interactions with fixed offshore substructure was carried out by computational fluid dynamics, and comparison with other experiments and simulations results was conducted.

• Journal of KSNVE
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• v.10 no.4
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• pp.610-614
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• 2000

Cellular Automata(CA)s are used as a simple mathematical model to investigate self-organization in statistical mechanics, which are originally introduced by von Neumann and S. Ulam at the end of the 1940s. CAs provide a framework for a large class of discrete models with homogeneous interactions, which are characterized by the following fundamental properties: 1) CAs are dynamical systems in which space and time are discrete. 2) The systems consist of a regular grid of cells. 3) Each cell is characterized by a state taken from a finite set of states and updated synchronously in discrete time steps according to a local, identical interaction rule. 4) The state of a cell is determined by the previous states of a surrounding neighborhood of cells. A cellular automaton has been attracted wide interest in modeling physical phenomena, which are described generally, partial differential equations such as diffusion and wave propagation. This paper describes one and two-dimensional analysis of wave propagation phenomena modeled by CA, where the local interaction rules were derived referring to the Lattice Gas Model reported by Chen et al., and also including finite difference scheme. Modeling processes by using CA are discussed and the simulation results of wave propagation with one wave source are compared with that by finite difference method.

• International Journal of Aeronautical and Space Sciences
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• v.16 no.4
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• pp.560-570
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• 2015

We present a simulation of a hybrid Reynolds-averaged Navier Stokes / Large Eddy Simulation (RANS/LES) based on detached eddy simulation (DES) for a Burrows and Kurkov supersonic planar mixing experiment. The preliminary simulation results are checked in order to validate the numerical computing capability of the current code. Mesh refinement studies are performed to identify the minimum grid size required to accurately capture the flow physics. A detailed investigation of the turbulence/chemistry interaction is carried out for a nine species 19-step hydrogen-air reaction mechanism. In contrast to the instantaneous value, the simulated time-averaged result inside the reactive shear layer underpredicts the maximum rise in $H_2O$ concentration and total temperature relative to the experimental data. The reason for the discrepancy is described in detail. Combustion parameters such as OH mass fraction, flame index, scalar dissipation rate, and mixture fraction are analyzed in order to study the flame structure.

• Proceedings of the Korea Society for Simulation Conference
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• 2005.11a
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• pp.144-149
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• 2005

본 논문에서는 $CAVEW^{TM}-like$ 시스템과 같은 대형 디스플레이 기반의 몰입형 시뮬레이션 환경에 필요한 인터랙션 기법을 제안한다. 축소 모형(miniature) 인터랙션은 원거리에 있는 객체를 쉽게 선택하거나 조작하기 위하여 가상 세계 전체를 축소하여 사용자 근처에 디스플레이하고 이를 조작함으로써 대상 객체와 상호작용 할 수 있도록 해준다. 또한, 조감도(bird's eye view)로 표현되는 지도상에 사용자 위치를 표시하여 가상 세계 탐색시 이동 경로를 쉽게 파악할 수 있도록 하였다. 축소 모형은 투명 패널 인터페이스를 통하여 보여지며 사용자는 이를 이용하여 택타일 피드백(tactile feedback)을 제공 받을 수 있다. 그리드(grid)를 이용한 비주얼 가이더는 가상 세계 내에 그리드를 디스플레이하여 대상 객체와 사용자간의 위치 관계를 쉽게 파악할 수 있도록 해준다. 일반적으로 대형 디스플레이 환경에서의 인터랙션은 정확한 깊이 인식이 어렵기 때문에 인터랙션 시사용자의 불필요한 행위를 유발하게 된다. 본 논문에서 제안하는 기법은 이 같은 문제점을_개선하여 객체 조작 시 느껴지는 피로감을 최소화 시킬 수 있으며 다양한 몰입 및 상황 기반 시뮬레이션 어플리케이션에 적용되어 활성화 될 수 있다.

• Nuclear Engineering and Technology
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• v.26 no.2
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• pp.257-264
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• 1994

Experimental studies hate been peformed to investigate vapor explosion phenomena which may threaten the containment integrity during severe accidents in nuclear power plants. In this study, experimental equipment is constructed for vapor explosion experiments, and the vapor explosion experiments were conducted using water/R22. During the experiments, water/R22 interaction phenomena were observed using the high speed camera, and the explosion pressure and released mechanical energy were measured with pressure transducer and pressure relief tube. And the effects of some important parameters-hot liquid temperature, hot liquid injection velocity, hot liquid injection velocity, hot liquid injection time, and cold liquid depth-were investigated on the vapor explosion. Also, the experiment with grid was conducted to study reactor -vessel-lower-structure effect on fuel/coolant interaction. Water/R22 explosion conversion ratios were measured between 0.5∼1.6%.

• Journal of Korean Society on Water Environment
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• v.27 no.5
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• pp.661-669
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• 2011

The purpose of this study is quantitative analysis of the effects of the interactions between stream network and hillslope to hydrologic response functions. To this end general formulation of hydrologic response function is performed based on width function and grid framework. Target basins are Ipyeong and Tanbu basins. From the results of width function estimation even similar sized and closely located basins could have very different hydrologic response function. It is found out that the interactions between stream network and hillslope are essential factors of rainfall-runoff processes because their difference can make the hydrologic response function with positive skewness. The change of velocities of stream network and hillslope might influence the magnitude of peak but time to peak tends to more sensitively respond to velocities of stream network. Lag time of basin would be the result of complex interaction between drainage structures and dynamic properties of river basin.

• 한국전산유체공학회:학술대회논문집
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• 2009.11a
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• pp.151-158
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• 2009

To implement the insects' flapping flight for developing flapping MAVs(micro air vehicles), the unsteady flow characteristics of the insects' forward flight is investigated. In this paper, two-dimensional FSI(Fluid-Structure Interaction) simulations are conducted to examine realistic flow features of insects' flapping flight and to examine the flexibility effects of the insect's wing. The unsteady incompressible Navier-Stokes equations with an artificial compressibility method are implemented as the fluid module while the dynamic finite element equations using a direct integration method are employed as the solid module. In order to exchange physical information to each module, the common refinement method is employed as the data transfer method. Also, a simple and efficient dynamic grid deformation technique based on Delaunay graph mapping is used to deform computational grids. Compared to the earlier researches of two-dimensional rigid wing simulations, key physical phenomena and flow patterns such as vortex pairing and vortex staying can still be observed. For example, lift is mainly generated during downstroke motion by high effective angle of attack caused by translation and lagging motion. A large amount of thrust is generated abruptly at the end of upstroke motion. However, the quantitative aspect of flow field is somewhat different. A flexible wing generates more thrust but less lift than a rigid wing. This is because the net force acting on wing surface is split into two directions due to structural flexibility. As a consequence, thrust and propulsive efficiency was enhanced considerably compared to a rigid wing. From these numerical simulations, it is seen that the wing flexibility yields a significant impact on aerodynamic characteristics.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.3
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• pp.191-198
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• 2014

During multi-physics or multi-phase simulations accompanying fluid- structure- thermal interaction, data transfer problems always arise along non- matching interfaces caused by different computational meshes for each physical domain. Common- refinement scheme, among many available methods, is attractive since it is known to yield conservative and accurate data transfer for non- matching interface cases. This is particularly important in simulating compressible unsteady fluid- structure- thermal interaction inside solid propellant rockets, where grid size along solid- fluid interfaces is substantially different. From this perspective, we examine performances of common- refinement- based data transfer scheme between structured quadrilateral (structure part) and unstructured triangular (fluid part) meshes by comparing computed results with other data transfer methods.

• Journal of KIISE:Computing Practices and Letters
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• v.10 no.2
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• pp.189-198
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• 2004

As display devices evolve, computer-based work environments are also becoming better suited to actual application tasks. This paper discusses the development of an architectural design system using the virtual table, which is a table-type projection system. It consists of the interactive VR modeler, the hybrid tracker and the architectural interpreter. The interactive VR modeler offers visual and tactile guide such as grid interaction, a tangible transparent prop and reference objects, so that a user can design architectural 3D models more easily and intuitively on the virtual table. The hybrid tracker includes two types of tracking methods for viewpoint according to the user's view and hand interaction: namely, vision-based tracking and magnetic tracking. The architectural interpreter automatically transforms simple 3D masses into a basic construction form that has architectural knowledge. The proposed system has advantage in the sense that it is suitable for collaboration among several users, allowing them to view graphical objects in stereoscopic view with direct 3D manipulation. Thus, it can be effectively used for architectural simulation and user-participated design.