• Journal of Ocean Engineering and Technology
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• v.20 no.5 s.72
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• pp.23-29
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• 2006

A quasi depth-varying mathematical model for wind-generated circulation in coastal areas, expressed in terms of the depth-averaged horizontal velocity components and free surface elevation was validated and used to understand the diurnal circulation process. The wind velocity is considered as a dominant factor for driving the current. In this paper, three-dimensional numerical experiments that included the land topography were used to investigate the mesoscale air flaw over the coastal regions. The surface temperature of the inland area was determined through a surface heat budget consideration with the inclusion of a layer of vegetation.A series of numerical experiments were then carried out to investigate the diurnal response of the air flaw and wind-generated circulation to various types of surface inhomogeneities.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.5
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• pp.97-103
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• 2006

A meso-scale analysis method using the natural element method, which is a kind of meshless method, is proposed for the analysis of material damage of brittle microcracking solids such as ceramic materials, concrete and rocks. The microcracking is assumed to occur along Voronoi edges in the Voronoi diagram generated using the nodal points as the generators. The mechanical effect of microcracks is considered by controlling the material constants in the neighborhood of the microcracks. The macro elastic moduli of anisotropic as well as isotropic solids containing a number of randomly distributed microcracks are calculated in order to demonstrate the validity of the proposed method.

• Journal of Environmental Science International
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• v.5 no.6
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• pp.727-738
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• 1996

An one dimensional atmosphere-canopy-soil interaction model is developed to estimate of the heat budget parameter in the atmospheric boundary layer. The canopy model is composed of the three balance equations of energy, temperature, moisture at ground surface and canopy layer with three independent variables of Tf(foliage temperature), Tg(ground temperature), and qg(ground specific humidity). The model was verilied by comparative study with OSUID(Oregon State University One Dimensional Model) proved in HAPEX-MOBILHY experiment. Also we applied this model in two dimensional land-sea breeze circulation. According to the results of this study, surface characteristics considering canopy acted importantly upon the simulation of meso-scale circulation. The factors which used in the numerical experiment are as follows ; the change for a sort of soil(sand and peat), the change for shielding factor, and the change for a kind of vegetation.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.6
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• pp.716-723
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• 2006

A meso-scale analysis method using the natural element method is proposed for the analysis of material damage of brittle microcracking solids. The microcracking is assumed to occur along Voronoi edges in the Voronoi diagram generated using the nodal points as the generators. The mechanical effect of microcracks is considered by controlling the material constants in the neighborhood of the micorcracks. The macro elastic moduli of isotropic solids containing a number of randomly distributed microcracks are calculated considering the effect of microcrack closure to demonstrate the validity of the proposed method.

• Interaction and multiscale mechanics
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• v.3 no.3
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• pp.257-266
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• 2010

A novel resonance based proximity DC current sensor is proposed. The sensor consists of a piezo sensed and actuated cantilever beam with a permanent magnet mounted at its free end. When the sensor is placed in proximity to a wire carrying DC current, resonant frequency of the beam changes with change in current. This change in resonant frequency is used to determine the current through the wire. The structure is simulated in micro and meso scale using COMSOL Multi physics software and the sensor is found to be linear with good sensitivity.

• International Journal of Precision Engineering and Manufacturing
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• v.6 no.2
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• pp.5-11
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• 2005

Among the micro machining techniques, micro EDM is generally used for machining micro holes, pockets, and micro structures on difficult-cut-materials. Micro EDM parameters such as applied voltage, capacitance, peak current, pulse width, duration time are very important to fabricate the tool electrode and produce the micro structures. Developed micro EDM machine is composed of a 3-axis driving system and RC circuit equipped with pulse generator. In this paper, using micro EDM machine, the characteristics of micro EDM process are investigated and it is applied to micro holes, slots, and pockets machining. Through experiments, relations between machined surface and voltages and between MRR and feedrate are investigated. Also the trends of tool wear are investigated in case of hole and slot machining.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.5 no.2
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• pp.121-132
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• 1993

A three-dimensional barotropic model is used to compute meteorologically-induced circulations in the East Sea for monthly, seasonal and annual basis. The computed barotropic responses have shown that in the upper part of the 40$^{\circ}$ North latitude. counterclockwise meso-scale eddies have been formed off Dong Han Man, middle part of the East Sea and sea area between the Siberian coast and Hokkaido throughout the year except summer season. These results are in good agreements with some of earlier schematic circulation diagram.

• 한국연소학회:학술대회논문집
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• 2013.06a
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• pp.41-43
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• 2013

In order to simulate and visually observe combustion phenomena in cylindrical radial-flow porous inert media, a radial multi-channel burner, made of transparent quartz plates, was fabricated. Flame stabilization characteristics and its pulsating instability in the burner were experimentally investigated with respect to various mixture flow rates and equivalence ratio. As a result, five different flame behaviors, such as stable flame, pulsating instability, sudden extinction, blowout and unstable extinction, were observed. Mean radial position of circularly arranged multi-flame and its averaged burning velocity were measured and then compared to the freely propagating flame. The multi-flame pulsation frequency is about several tens of Hz and it is supposed to be generated by the heat diffusion enhancement to cold pre-mixture by the intensive gas-solid interaction.

• Transactions of Materials Processing
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• v.24 no.3
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• pp.194-198
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• 2015

Microstructure based FE simulations were conducted to investigate the micro-mechanical properties of ferrite-martensite dual-phase steels. The FE model was built based on real microstructure images which were characterized by optical microscopy through the thickness direction. Serial sectioned 2D images were converted into semi-2D representative volume elements (RVEs) model. Each RVE model was subjected to a non-proportional loading condition and the mechanical response was analyzed on both the macroscopic and microscopic levels. Macroscopically, stress-strain curves were described under tension-compression and tension-orthogonal tension conditions and the Bauschinger effect was well captured for both loading paths. In addition, micromechanical properties were investigated in the view of stress-strain partitioning and strain localization during monotonic tension.

• Composites Research
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• v.32 no.5
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• pp.249-257
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• 2019

In this paper, the buckling behavior of triaxially braided circular arch with monosymmetric open section subjected to three-point bending was studied experimentally and numerically. First, test specimens were manufactured using vacuum assisted resin transfer molding (VARTM). Then the specimen was tested under three-point bending to determine the ultimate buckling strength. Before performing the numerical analysis, effective material properties of the braided composite were obtained through micro-meso scale analysis virtual testing validated with available test results. Then linear buckling analysis and geometrically non-linear post buckling analysis, established to simulate the test setup, were performed to study the buckling behavior of the composite frame. Analysis results were compared with experimentally obtained ones for verification. The effect of manufacturing defects of tow misalignment, irregular surface and resin rich region, and uncertainties during test setup were studied using numerical models. From the numerical analyses performed it was observed that both manufacturing defect and uncertainties had effect on the buckling behavior and strength.